the authoritative magazine about high fidelity november 1973 60c

the authoritative magazine about high fidelity november 1973 60c
THE AUTHORITATIVE MAGAZINE ABOUT HIGH FIDELITY
NOVEMBER 1973 60C
23602
www.americanradiohistory.com
AmericanRadioHistory.Com
(Left to right) Jerry Fisher, lead vocalist, Blood, Sweat & Tears
Bobby Colomby,
Walt "Clyde" Frazier, New York Knicks
drums, Blood, Sweat & Tears
Andy
Henry Lewis, conductor, New Jersey Symphony
Warhol, movie producer-director
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controls for front and rear channels,
function and mode selector with
multi -colored indicator lights. Further
source is in operation, the sound
level of each channel can be
monitored by viewing the large scope type level indicator on the top two
models. Left and right front/rear
controls permit instant adjustment.
Indicator sensitivity controls allow for
a maximum of -30dB adjustments
at any sound level. The level indicator
may also be used to view CD -4
channel separation adjustments made
with the CD -4 separation controls.
-
Four -Channel Level Indicator See what
you hear. Make instant adjustments with
left/right, front/rear level controls.
electronic trigger relay system is
used to protect the speakers from DC
leakage or overload.
New and exclustve
Power Boosting circuit
When switching from four -channel to
two -channel reproduction, power is
substantially increased with the new
and advanced Power Boosting circuit,
as described above. This exclusive
circuit is built into both the QX-949
and QX-747 models.
Another plus feature attributable
to the Power Boosting circuit is
simplified switching from four-channel
to two -channel operation. It can be
instantly achieved without the usual
re -connecting of speaker wires. This,
too, is a Pioneer exclusive.
A tuner section the equal of
separate components
The FM tuner section of the QX-949
truly an engineering accomplishment. It inzorporates two dual -gate
MOS FET's in the front end, plus
three ceramic filters and 6 -stage
limiters in a monolithic IC in the IF
stage. The result is superb sensitivity
and selectivity, and excellent signal
is
to noise ratio.
Advanced circuitry includes Dolby
adaptor input/output and 4 -channel
broadcasting multiplex output terminal
anticipation of the future use of
discrete quadraphonic broadcasting,
the QX-949 and QX-747 include a
quadraphonic multiplex output
terminal. Depending on the system
finally approved, all that ever will be
required is a simple adaptor unit.
And speaking of adaptor units, both
the QX-949 and QX-747 highlight an
input/output for a Dolby noise
reduction adaptor unit.
In
Unique 4 -channel level indicator
Regardless which quadraphonic
refinement is offered with the
QX-949's multiplex noise and high/
low filters, plus signal strength and
center tuning meters in one housing.
Admittedly, these new Pioneer
quadraphonic receivers, like fine
sports cars or cameras, are not
inexpensive. However, they represent
the high fidelity industry's most
outstanding value. We have built
them with the same quality. precision
and performance you've come to
Inputs/ Outputs for total versatility
Pioneer has endowed these models
with terminals for a wide range of
program sources. The only limitation
is your own listening interests and
your capability to experiment with
sound.
expect from Pioneer stereo equipment. We offer them to you with the
same pride and conviction that has
always compelled you to say
"Pioneer, the very best."
QX-949 - $699.95; QX-747 $599.95; QX-646 - $499.95. Prices
Convenient features increase
listening enjoyment
Along with the total capability of
these receivers, Pioneer has incorporated a wide array of additional,'
meaningful features. All three
instruments include: loudness
contour, FM muting, an extra wide
tuning dial, two sets of bass/treble
Specifications
Amplifier
4 -ch. RMS power, 8
4 channels driven,
ohms,
20-20KHz
4 -ch. IHF
2 -ch.
RMS power, 8 ohms,
both channels driven,
20-20KHz
2 -ch. IHF
THD/IM Distortion
FM Tuner
FM Sensitivity (IHF)
(the lower the better)
Selectivity
(the higher the'better)
Capture Ratio
(the higher the better)
QX-747
20 watts/
OX -949
40 watts/
channel
240 watts (80)
380 watts (40)
60 watts/
OX -646
10 watts/
channel (1KHz)
channel
160 watts (89)
2?,0 watts (42)
40 watts/
80 watts (89)
108 watts (49)
channel
channel
channel
150 watts (89)
230 watts (40)
120 watts (80)
170 watts (40)
40 watts (80)
54 watts (40)
0.3%
(20-20KHz)
0.5%
(20-20KHz)
1%
(1 KHz)
1.8uV
1.9uV
2.2uV
80dB
60dB
40dB
1dB
1dB
3dB
70dB
70dB
65dB
2
1
1
2 (4 -ch.)
1
2 (2 -ch.)
1
(4 -ch.)
(2 -ch.)
(4 -ch.)
1
(4 -ch.)
(the lower the better)
S/N Ratio
include walnut cabinets.
U.S. Pioneer Electronics Corp.,
178 Commerce Road, Carlstadt,
New Jersey 07072
West: 13300 S. Estrella, Los Angeles
90248 / Midwest: 1500 Greenleaf,
Elk Grove Village, Ill. 60007
Canada: S. H. Parker Co.
_
13
watts/
(1
KHz)
Inputs
Phono
Tape Monitor
Dolby adaptor input
1
Auxiliary
1
1
1
1
(4 -ch )
(2 -ch.)
1
Outputs
Speakers
2
2
Headset
Dolby adaptor output
Tape Rec.
4-ch. MPX
CO
output
(Front)
(Rear)
1
2
(Front)
(Rear)
1
1
(Front/Rear)
(Front/Rear)
(4 -ch.)
1
2 (4 -ch.)
1
2 (2 -ch.)
1
1
1
1
PIONEER`
when you want something better
Check No 47 no Reader Serv,ce Card
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1
2
(Front)
(Rear)
1
(Front)
(4 -ch.)
(4 -ch.)
(2 -ch.)
1
1
(4 -ch )
(2 -ch.)
o
You're
Audio
reading
this page
for the
same
reasons
we build
our
speakers.
NOVEMBER, 1973
Successor to RADIO Est. 1917
Vol. 57, No.
11
FEATURE ARTICLES
Richard C. Heyser
Dick Crawford
20 Breakthrough in Speaker Testing
34 Bass Equalization in Speakers
38 Addenda to Annual Product Directory
44 Cassette Tape Recording Bias
52 Christmas Buying Guide
54 Equalization in the Home
86 The Kennedy Center
92 Audio ETC
Martin Clifford
John Eargle
Martha Sanders Gilmore
Edward Tatnall Canby
EQUIPMENT PROFILES
STR-7065
GXC-46D
280DR
70 Sony Receiver
72 Akai Cassette
76 RTR Speaker
Recorder
RECORD REVIEWS
100
including the attack of tympani
and organ. An almost tactile
feeling of presence. And
transparent highs, providing
AUDIO IN GENERAL
4
unusual instrumental definition.
4
First and foremost, we built
the LDL 749A to satisfy our own
desire for musical enjoyment.
Including the spatial sensations:
from the intimacy of small
groups to the awesomeness of
full orchestra.
6
With their precise combination
of forward-radiatec sound and
panoramic reflection, LDL 749A
are a compact, elegant way to
put the concert hall in your
listening room. And the price is
as realistic as the sound!
8
Sherwood L. Weingarten
Edward Tatnall Canby
Sherwood's Forest
Classical Record Reviews
96
Better music, wherever you
listen. Real fundamental, bass,
Coming in December
Audioclinic Joseph Giovanelli
Tape Guide Herman Burstein
Dear Editor ..
14
Behind the Scenes Bert Whyte
80 Advertising Index
106
Classified Advertising
.
EDITOR Eugene Pitts III
ASSOCIATE EDITOR Edward Tatnall
ASSOCIATE EDITOR Bert Whyte
ASSISTANT EDITOR Peggy Bicknell
PUBLISHER
Jay
L.
Butler
Canby MARKETING DIRECTOR Sanford L. Cahn
COVER DESIGN John Kwasizur
CIRCULATION MANAGER Jean Davis
Herman Burstein, Martin Clifford, Leonard Feldman, RichC. G. McProud, Harry E.
Maynard, Alexander Rosner, George W. Tillett, Sherwood L. Weingarten.
CONTRIBUTING EDITORS:
ard Freed, Martha Sanders Gilmore, Joseph Giovanelli,
is published monthly by North American Publishing Co.. Irvin J. Borowsky.
President: Frank Nemeyer, Jay L. Butler and Roger Damio. Vice Presidents: R. Kenneth Baxter. Vice President/Production:
Nate Rosenblatt, Promotion Director; Mary Claffey. Circulation Director.
RATES-U.S. Possessions, Canada, Mexico. $6.00 for one year; $10.00 for two years; all other countries. $9.00 per year.
Printed in U.S.A. at Columbus, Ohio. All rights reserved. Entire contents copyrighted 1973 by North American Publishing
Co. Second class postage paid at Philadelphia. Pa. and additional mailing office. Back issues, $2.00 each.
REGIONAL SALES OFFICES: Jay L. Butler, Publisher and Sanford L. Cahn. Marketing Director, 41 East 42nd St.,
New York. N.Y. 10017, telephone (2121 687-8924.
Jay Martin, 15010 Ventura Blvd., Sherman Oaks, Calif. 91403, telephone (213) 981-7852.
REPRESENTATIVES: Continental Europe: John Ashcraft. 12 Bear St.. Leicester Square. London W.C.2, telephone 01930-0525. For Benelux and Germany. W.J.M. Saunders. Mfg., Herengracht 365. Amsterdam. Holland. telephone 24.09.08.
Japan: Japan Printing News Co., Ltd., No. 13.2 Chome Ginza Higasi. Chuo-ku. Tokyo. telephone 541-5795.
AUDIO (title registered U.S. Pat. Off.)
TO
Linear
Design
Labsinc.
20 Willett Avenue. Port Chester,
N.Y.
AUDIO Editorial and Publishing Offices, 134 N. 13th St., Philadelphia, Penna. 19107
Postmaster: Send Form 3579 to the above address
10573
2
AUDIO
NOVEMBER 1973
Garrard introduces
its new models.
ZERO 100c
The Zero
Tracking
Error
Tonearm
True tangent tracking
geometry. Zero 100c
and Zero 92 tonearms.
This season, we have brought out four entirely new
units in the Component line, and refined the already
famous ZERO 100, now in its third year of production.
This unique Zero Tracking Error automatic turntable, which has earned the overwhelming regard
of the critics, now becomes the ZERO 100c, and
includes further advancements; including a built-in,
automatic record counter ... making the ZERO 100c
the finest automatic turntable available at any price.
The Garrard policy of pursuing useful technical
innovations and resisting "change for the sake of
change," has paid off handsomely this year. Most
notably, the articulating Zero Tracking Error Tone arm, Garrard's revolutionary patented design, has
been incorporated in the ZERO 92, a new model at
lower cost than the ZERO 100c. In addition, three
other models, the 82, 70 and 62 have been introduced. The entire series, both in styling and
features, reflects the ZERO 100c design philosophy.
This year, more than ever, there is a Garrard
automatic turntable to suit your specific needs. Your
dealer will help you select the model that will best
complement your system
whether that system
is mono, stereo, 4 -channel, matrix or discreet.
...
ZERD 92
ZERO 100c
Two speed Automatic Turntable with articulated
computer -designed Zero Tracking Error
Tonearm. Features: Variable speed ±3%;
Illuminated Stroboscope; Built-in automatic
record counter; Magnetic anti -skating control;
Sliding weight stylus force setting; 15° vertical
tracking and cartridge overhang adjustment;
Damped Cueing/Pausing in both directions;
Patented Synchro-Lab Synchronous Motor.
$209.95*
ZERO 92
Three speed Automatic Turntable with articulated
Zero Tracking Error Tonearm. Features: Lever
type anti -skating adjustment; Sliding weight
stylus force setting; 15° vertical tracking
and cartridge overhang adjustments; Cueing/
Pausing control, Damped in both directions;
Patented Synchro-Lab Motor. $169.95'
MODEL 82
Three speed Automatic Turntable with low-mass
extruded aluminum tonearm. Features: Lever
type sliding weight anti -skating adjustment;
Sliding weight stylus force setting; 15° vertical
tracking and cartridge overhang adjustments;
Cueing/Pausing control, Damped in both directions; Patented Synchro-Lab Motor. $119.95*
MODEL 70
Three speed Automatic Turntable with low-mass
aluminum tonearm and fully adjustable stylus
pressure setting. Features: Torsion spring
anti -skating control; Cueing/Pausing control;
2 point record support; Patented Synchro-Lab
Motor. $89.95*
MODEL 62
Three speed Automatic Turntable with low -mass
aluminum tonearm, fixed counterweight, and
adjustable stylus pressure. Features: Torsion
spring anti -skating control; Cueing/Pausing
control; 2 point record support; Heavy duty
four -pole Induction Surge Motor. $69.95*
MODEL 32
Dist. by British Industries Company, Westbury, New York 11590
Mfg. by Plessey Ltd.
/ A Div. of Avnet,
'Less base and cartridge
Inc.
GAIRIRAIRD
Check No. 17 on Reader Service Card
olnAudioclinic
09
Joseph Giovanelli
December
Focus on Microphones
How to Record Live in Two and
Four Channels-Jim Gordon
Microphones-The Vital Link
in the Recording Chain-David
Lane Josephson
Fundamentals of Loudspeaker
Design-Michael Lampton and
Lee M. Chase
Profiles Include
Kenwood KR -6340 four -channel
Equipment
receiver ESS Heil amt -1 speaker
system
Classical, pop/rock, and jazz record reviews
Musical Instrument Versus Hi Fi
Sound
Q. I am planning to construct a bass
reflex enclosure with a duct behind the
port.
I want to build a system which can
handle the sound of a pedal steel guitar
and also play recorded music. The loudspeakers I plan to use are designed for
musical instrument reproduction. I am
interested solely in reproducing rock
and jazz; basically, music produced by
guitar, bass, drums and organ.
With the help of a graphic equalizer,
can I smooth out the response for recorded music?-Dennis Lipster, Belle rose, New York
have not found it possible
to make speakers designed for musical
instruments produce good sound for
high fidelity systems.
Musical instrument speakers are designed to produce certain colorations
so that the instruments have a specific
sound quality. Therefore, some people
do feel that such speakers will be
great for reproducing these same
sounds. Remember, however, that the
sound has already been colored by
the nature of the speakers originally
producing the sound. It will be colored
once again during playback. The
quality or alterations of quality, therefore, will be enhanced. This "enhancement" may not be an improvement in
quality.
A graphic equalizer will not smooth
out speaker resonances and dips. These
speaker abberations are much sharper
than the equalizer's filters.
I suggest, therefore, that you use
two separate sets of speakers: one for
live playing, and another for sound
reproduction.
A. I
BRfiARTHROUC+H. IN
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About the cover:
Equalizers,
the subject of our editorial
focus this month, are becoming
increasingly popular as more
people come to understand their
uses. Good units can make up
for deficiencies in response of
most any component in the
system, and they can correct
many difficulties in room acoustics. Equalizers are used by
sound reinforcement people to
help cure feedback so that the
overall level of the system can
be
increased,
and speakers
manufacturers use equalizers with
specific characteristics to normalize response. All in all, equalizers
are one of the most useful
tools the audiophile has to
change the characteristics of the
sound in his listening room.
Using an Equalizer
Q. The idea of an equalizer working
over many different frequency ranges to
compensate for room differences fascinates me, but who is to tell me whether
I
am going to make matters better or
worse by twiddling with the controls?
My present amplifier, in addition to
bass and treble controls, has a contour
control, which, believe me, affects the
bass. I will go for a month without
emphasizing the bass and then decide
that things sound thin and go another
month the other way.
Do equalizer manufacturers provide
advice or test recommendations which
will protect me against my own bad
musical judgment?-Francis Woodbridge, Boston, Massachusetts
A. An individual's ideas of good
musical sound can change from time to
time. I do not think, therefore, that
you need "protection."
Some manufacturers of equalizers
do offer guides for the initial setup
and adjustment of an equalizer to
compensate for deficiencies in the
loudspeaker system and in room acous-
tics.
We might sometimes want to compensate for deficiencies in the sound
of the discs or tapes or to accommodate
our own feelings at a given time.
Therefore, just make changes in equalization whenever they seem necessary.
Listening to music is a highly subjective experience. There is really no
right or wrong way to listen to audio.
Listen in accordance with your mood.
Forget logic. If you enjoy the results
you can achieve with an equalizer,
this enjoyment is what counts.
While such equalizers are capable
of producing great changes in the
quality of sound it is likely that you
will only need to make small changes
of the setting of any given control
to produce a useful enhancement to
your enjoyment of music.
It is generally a good idea to record
tapes without using the equalizer. The
equalizer can then be used during playback of these tapes. This is most true
when you first get your equalizer
because you will want to experiment
with it quite a bit. Once a tape has
been recorded with some equalization,
it could be difficult to alter the reproduction later on when you have learned
more about the uses and abuses to
which such equalizers are subject.
If you have
a problem or question on audio,
write to Mr. Joseph Giovanelli, at AUDIO,
134 North Thirteenth Street, Philadelphia,
Pa. 19107. All letters are answered. Please
enclose a stamped self-addressed envelope.
AUDIO
4
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NOVEMBER 1973
KLH is well into its second decade of manufacturing
extraordinary high performance loudspeakers that don't
cost an extraordinary amount of money. We've kept
costs down by making every loudspeaker ourselves. And by
selling a staggering number of them.
In short, we've had a lot of practice.
And that's perfect for you.
For now you can own a pair of our new Model
Thirty -One loudspeakers for just $89.95t. Think of it.
Two superb sounding full -range loudspeake-s at a price
you might consider fair for just one! A pair of Thirty -Ones
deliver a truly inordinate amount of sound for their
modest size. You can drive them to big listening levels
with virtually any decent amplifier or receiver. They're
handsome, featuring a new sculptured acoustically transparent foam grille. Rugged. And best of all, incredibly
inexpensive. With the money you save, you might even
trade -up to a better turntable or receiver, perhaps
even get into quadraphonic sound. The Thirty -Ones can
help make it happen. A pair is at your KLH dealer now.
Listen to them soon. We're sure you'll agree that no one
has ever offered you a better value in sound.
And we've had a lot of practice.
For more technical information, write to KLH Research
and Development, 30 Cross Street, Cambridge, Mass.
02139. Or visit your KLH dealer.
What
does it take to
make an important new
loudspeaker and
sell it for
$89.95`
a pair?
Practice.
A whole lot of practice!
illIllIllIfli I I I I I I IIIINNIII I I I I I I I I IIIIIIM"
KLH RESEARCH AND DEVELOPMENT CORP.
30 Cross St.,
Cambridge, Mass. 02139
tSuggested retail prices-slightly higher in the South and West.
Check No. 30 on Reader Service Card
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imagine:
THAT
A
Tape Guide
MANUFACTURER
DEVELOPED A TRANSMISSION
Herman Burstein
LINE SPEAKER THAT COULD
EQUAL OR BETTER THE
BEST BOOKSHELFS FOR
$150 -$200
Tape Thickness
Dear Mr. Burstein,
I am writing in reference to the first
item "Tape Length" which appeared in
your Tape Guide section of the April,
of AUDIO.
Perhaps by now you have received
all sorts of comments to your statement,
"For anything like good results, 1/2 mil
tape is generally not recommended."
It has been the experience of cassette
manufacturers that 1/2 mil (C-60)
cassettes are preferred by knowledgeable audiophiles for two reasons. (1)
The magnetic oxide coating is thicker
on C-60 tapes than on C-120 and some
C-90 tapes. Consequently, saturation
and distortion is less of a problem and
dynamic range is improved with C-60
tapes. (2) C-60 th mil base film is less
likely to cause physical and mechanical
problems. Usually it winds up better
so there is less edge damage and consequently less edge program distortion
or dropouts. Statistically, the mechanical
jamming rate among cassette manufacturers is far less with C-60 than with
C-120 cassettes.
With reliable cassette transports that
are properly maintained, "name brand"
cassettes rarely cause the tape speed
slow down or excessive wow and flutter
problems that Mr. Thurwachter mentioned. However, if the torque required
to drive a cassette is at the upper limits
of the IEC specification and if the
transport batteries are not at full
strength, these mechanical problems
1973 issue
RSL
211S
imagine:
YOU COULD BUY IT
WHOLESALE FOR
599.95
ROGERSOUNO
LABS
will occur.
John E. Jackson
Manager
l91,V3{1
BASF Systems
O
MANY MODELS TO CHOOSE
You are completely correct. The state
of the art has changed so that, at least
for cassette, mil tape, which is used in
%a
FROM-ALL FACTORY DIRECT.
FREE TRIAL ON ALL
RSL SPEAKERS
6319 VAN NUYS BLVD.
VAN NUYS, CA. 91401
Phone: (213)78 -SOUND
the C-60 cassettes, does a fine job. In
fact, I have found that at least one
manufacturer's C-90 and C-120 cassettes,
which use tapes even thinner than ' mil,
do a surprisingly good job. My comments
about % mil tape do not apply to cassettes, where % mil and thinner tapes
are giving very good performance.
The Tape Guide did not mean to
imply that % mil tape (C-60) is worse
than thinner tapes (C-90 and C-120). It
meant that 11/2 mil and 1 mil tapes are
better than % mil tapes.
MatchingMicrophone Impedances
Q. I recently bought a Sony Mx -12
mixer. The manufacturer suggests that
I use low impedance mikes to feed it.
I have been using high Z mics with it.
Am I doing wrong? Is it important to
match the impedance?-Louis Hone,
Montreal, Canada
A. I have noticed that transistors do
not seem to care what kind of mikes
drive them, within reason, of course.
However, the use of high Z microphones
with circuits designed for low impedance
units will result in more mixer noise
because its inputs are not properly
terminated. I suggest, therefore, that
if you are using dynamic microphones,
you also use matching transformers to
lower their impedance. If your microphones are crystal units, you will lose
low frequencies by feeding them into
this mixer. This will be the case even
when you use a transformer with them.
No transformer can help because there
is none which can work into the high
impedance needed by crystal microphones.
Cassette Head Longevity
Q. What is the
deck? My cassette operates an average
of seven hours a day and about 12 hours
on weekend days. I have noticed a
notch on the face of the head, but I'm
not sure if it is a machined notch or
due to wear. From the information I
have given you, do I have a lot more
life left in the head?-Dennis G.
Mueller, APO San Francisco
A. In the case of open reel machines,
a good conventional head is considered
capable of giving 1,000 to 2,000 hours
of service. I don't think that a cassette
head would give more. So you can
judge whether the head in your cassette
machine is coming close to the time
of replacement. I doubt that the notch
you see in the head is a machined
notch.
If you have a problem or question on tape
recording, write to Mr. Herman Burstein at
134 North Thirteenth
AUDIO,
Street,
Philadelphia, Pa. 19107. All letters are
answered. Please enclose a stamped, selfaddressed envelope.
AUDIO
6
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usual life expectancy
of the record -playback head in a cassette
NOVEMBER 1973
Instead of talking about
a cassette deck with 3 heads
we make one.
The RS -2791J5.
It has an HE'FTM monitor head. So every
recording you make will be as sharp and clean
as it should be. That's recording insurance. The
kind of insurance that great specs alone can't
give. Only a monitor head can.
The monitor is more important in cassette
than it ever was in reel-to-reel. Because the
cassette can drag or jam without warning. And
it's prone to recording overload. Which can ruin
a potentially great recording if it isn't detected.
The RS -279 US also has many other desirable
design and convenience features. Like a dual
motor system. With a DC motor for the reel table-drive and our exclusive direct drive DC
motor for the capstan. Adjustable Doi'by*.
Switchable bias for Cr02 tapes. Solenoidoperated function controls. Locking pause.
Memory rewind. And Auto-Stop.
And the specs are just what you'd expect from
a deck with those credentials. The signal-tonoise ratio is better than 59dB Frequency
response is from 20-16,000 Hz. And wow and
flutter are less than 0.10%
The RS -279 US has the hallmarks of a great
cassette deck. Plus one that puts it ahead of
other decks. Our patented HPFT" monitor head.
The concept is simple. The execution is
precise. The performance is outstanding.
The name is Technics.
.
.
"Dolby is a trademark of Dolby Laboratores Inc.
2.00 PARK AVE., NEW YORK, N.Y. 10017
FOR YOUR NEAREST AUTHORIZED
TECHNICS DEALER, CALL TOLL FREE
800 447-47C0. IN ILLINOIS, 800 322-4400.
Technics
by Panasonic
Check No. 62 on header Service Card
a,
Ì11111111u111lIIi111111Attt111NN1DlIE11
1111n1bl9.11mt11Et4
.
_
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t 1,.n1411d.lciciiiEs6.
i;;
_:: :
Fil4irRi,i:
Dear Editor
Shure & CD -4
Dear Sir:
I would like to comment on Edward
Canby's most interesting and provocative article on phonograph cartridges in the June issue of AUDIO.
Since he has raised several very pertinent questions regarding the future
The
QUAD
Electrostatic was the
first full range electrostatic
produced commercially
and is still the standard by which ali others
are judged. Using closely coupled moving
elements some two hundred times lighter
than the diaphragms of moving col loudspeakers and being entirely free of cabinet
resonances and colouration, this loudspeaker overcomes the uual major problems of loudspeaker design and provides
remarkably natural reproduction of sound.
This explains why the QUAD electrostatic
loudspeaker is used by broadcast.pg and
recording organisations all over theworld,
in applications where quality is of prime
importance, and as a standard of reference by the majority of loudspeaker
manufacturers.
QUAD for the closest approach to
the original sound.
loudspeaker'';.,
QUAD
is a registered
trademark
For details of your nearest dealer
write to Acoustical Manufacturing Co. Ltd.,
Huntingdon PE17 7D8, England.
Check No.
3 on
Reader Service Card
direction of cartridge development,
I would like to answer those questions
insofar as possible.
Shure's position is that we will
provide the best quality cartridge for
all record formats that are produced.
We will certainly endeavor to satisfy
the requirements of the CD -4 system,
as well as the matrix and standard
stereo. This does not mean, however,
that we-or other cartridge manufacturers-can produce a single cartridge that will be the ultimate solution
for all systems. It may be that several
cartridges will be required, each being
the optimum for a given system.
In the case of the V-15 III, our
objective was to provide the finest
phono cartridge possible for the present-day standard stereo disc. This does
not mean that we intend to ignore the
CD -4 system or any other system. It
simply recognizes the fact that the
number of CD -4 discs available today
is miniscule compared to the millions
of standard stereo discs that have
been produced over the past 16 years.
Even today, the Schwann catalog of
records shows approximately 30K
stereo discs and certainly fewer than
30 CD -4 discs. The V-15 III has been
optimized to satisfy the requirements
of the standard stereo disc.
The V-15 III will track most present-day records at 3/4 gram. Cartridges
being sold for operation with the CD -4
system are specified at two grams.
The design of a cartridge that will play
satisfactorily at 3/4 gram is significantly
different from that which will play at
two grams. We feel that the lower
tracking force is an extremely important feature of a top-quality stereo
cartridge. We have run extensive life
tests, which show that the life of a
diamond tip increases exponentially
as tracking force decreases, as long as
the cartridge tracks properly. For cartridges in the price range of the V-15
III, we believe that extending the life
of the stylus is a feature we owe to
our customers. We could not, therefore, countenance a change in the
design of the V-15 III that would require a higher tracking force.
In this article, Mr. Canby indicates
that the cartridges designed for the
CD -4 system are flat in frequency response out to 45,000 Hz. We have
tested all of the CD -4 cartridges that
we have been able to find, not only
for sale in the United States but in
Japan and Europe as well. All of these
cartridges have a rise in frequency
response above about 15 kHz, with a
peak in the 25 to 30 kHz region, approximately 10 dB above the 1 kHz
level; however, cartridges with such a
frequency response can and do work
with the CD-4 decoders that we have
used for test purposes. On the other
hand, we have found that there are
numerous other factors that can affect
the ability of the cartridge to work
with the CD -4 system; but the response, such as I have just described,
is satisfactory.
The frequency response I have described indicates a major resonance in
the 25 to 30 kHz region. A flat frequency response out to 45 kHz would
require either a major resonance beyond 45 kHz, or a very highly -damped
stylus system. Both possibilities would
require a dramatically different approach from that of present-day cartridges. Most probably, successful CD -4
cartridges will show a resonance around
30 kHz, with a fairly significant peak.
In order to provide proper trackability
for these cartridges, a tracking force
in the two-gram region is indicated.
One of the problems in developing a
cartridge for the CD -4 system is that
the system itself is still undergoing
development and improvement. In
the case of stereo, once the Westrex
cutter had been introduced, people
produced stereo records; and the phonograph cartridge was designed to
satisfy a reasonably fixed objective. In
the case of CD -4, there have been
numerous improvements in the technique of mastering the records and also
in the electronic circuitry for decoding
the signal. There also have been
changes in the record materials. Designing a cartridge to satisfy the requirements of the CD -4 system, as well
as the ear of the trained high-fidelity
listener, is not a static task.
We believe that it is necessary to
produce a cartridge designed specifically for the CD -4 system. At the
AUDIO
8
www.americanradiohistory.com
AmericanRadioHistory.Com
NOVEMBER 1973
oryOu
y
fell
%idiot OU need
If you're seriously into music
sound reinforcement you want more
than hi-fi products can give
But full professional studio gear costs an arm and a
yyou.
leg, and you pay for a lot of things you may not
really need.
That's why there's a TASCAM Model 10. It's an
8 -in, 4 -out mixing console, and it's just $1890.
With the Model 10 you get what you have to have.
Without sacrificing a single necessary function.
Each input module gives you mic and line attenuation, three bands of peak and dip equalization (two
with frequency selection), pre- and post -echo send and
receive circuitry, pan function, and a unique straightline fader.
Each of the four submasters has a meter control
switch (line/echo), independent monitor level control,
echo receive level control, and a straight-line fader.
You also get a master gain module and 4" VU meters
with LED peak indicators. Plus pre -wired facilities for
up to four additional input modules
and other optional accessories
including talkback, remote
transport control, quad pan -
ner, and headphone monitor.
That's what you need and that's what you pay for.
Some things, however, you may or may not need, and
we leave that choice up to you. For instance, the basic
Model 10 is high impedance in and out, but studio line
impedances are available optionally. You'll probably
want low impedance mic inputs, but you may not need
all low impedance line inputs. So we don't make you
pay for them. You can order any combination of high
and low input/output impedances according to your
application.
Details and specs on the Model 10 are available
for the asking. At the same time we'll tell you about our
new Series 70 Recorder/reproducers.
We've got what you need.
U TASCAM CORPORATION
5440 McConnell Avenue
Los Angeles, California 90066
Check No. 60 on Reader Service Card
www.americanradiohistory.com
AmericanRadioHistory.Com
present state of the art, such a cartridge will be able to perform adequately with standard stereo records;
however, we do not believe such a
cartridge can approach the ultimate in
reproduction of standard stereo records. For such reproduction, we offer
the V-15 III. Perhaps, some day in
the future, the qualities of these two
cartridges may be combined and the
ultimate may be offered for both
systems simultaneously. Until then,
we feel that individual cartridges optimized to satisfy each system should
be provided.
James H. Kogen
Vice President
Shure Bros., Inc.
Evanston, Ill.
A
New Recruit
Dear sir,
I have been buying your magazine
off the newsstand for some time now.
I have always thought it was the best.
The June and July issues, however, were
so good that I was moved to send for a
subscription.
The July articles about four -channel
by Len Feldman, Ben Bauer, and
Harry Maynard really sold me on
AUDIO. I have a four-channel system
and love it.
Keep up the good job.
Harry L. McDonald
Takoma Pk., Md.
Al
Stewart's Instrumentation
Dear sir,
Mr. Canby's review of my album
(Museum of Modern Brass) just came
to my attention. I'm delighted that you
felt about it as you did as well as
taking the time to write about it in
AUDIO.
The instrumentation of the group is
trumpets, each also playing flugelhom
and piccolo trumpet where called for
in the arrangements. The low horns
are tuba, bass trombone and French
horn, and the six rhythm are keyboard
(piano, organ, harpsichord, celeste,
electric piano), fender, two guitars,
percussion and drums.
I hope that the next album grooves
you as much as this one did.
Thanks for a beautiful article.
Al Stewart
New York, N.Y.
5
Master Tapes
Dear sir,
In a recent issue of AUDIO in the
"Dear Editor" section, I note that Mr.
J. E. Cade of Casonic Foundation and
DON'T SETTLE FOR AN ORDINARY POWER AMP
WHEN YOU CAN HAVE A BGW SUPER AMP!
"The 500R will take its place among the top high quality amplifiersWith both channels driven, the 500R delivers more than 225 watts into
8 ohms and over 400 watts per channel into 4 ohms, nearly a KILOWATT! There was no sign of crossover distortion even at milliwatt outputs
and overload characteristics were excellent"
audio magazine oct. 73
If you're serious enough about quality, but are not impressed with needless frills, your next amp will be a BGW.
Only BGW power amplifiers have:
Fail safe SCR crow bar circuit for the ultimate in speaker protection
Modular construction for painless service
Welded steel frame chassis for unmatched mechanical strength
Fuseless -circuit breaker design for elimination of human errors in fuse selection and
fastest response
Removable-totally enclosed heat sinks for efficient heat dissipation and personal safety
a few of the unique features to be found in BGW power amps. For details write:
These are only
BGW Systems
P.O. Box 3742
SYSTEMS
Beverly Hills, Ca. 90212
(2131 559-4860
Or see your local dealer
10
Check No. 67 on Reader Service Card
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Mr. Lee Kuby of Harman-Kardon are
looking for prime quality tape dubbings.
I have many high quality master tapes
available, almost all of which were
recorded by myself, at live concerts.
Most of the masters were done with
the help of the Dolby B system. I use
Sony C-500, Neumann U-87, and Vega
S-10 condenser mics. I can honestly
say that the tapes are extremely good.
Most of the performances were done by
excellent groups and include a wide
variety of music from full symphony
to pipe organ (both classical and
theatre types) to jazz, etc.
I also am looking for dubbings of
first rate material that is technically
excellent, and I trade tapes with others
in this country who are in my position.
We all are disgusted with the commercially available source material, and
the only way to really get first-rate
stuff is to do it ourselves.
I would be willing to make duplication of some of my tapes for worthy
causes or for trade. I would be pleased
if you would refer my name to others
who might have prime source material
available for my use.
Thank you.
Roger Sanders
1578 Austin St.,
Atwater, Calif. 95301
Separate Decoders
Dear sir,
I read with great interest the Leonard
Feldman article, "Evolution of Four Channel Equipment." He makes a
number of interesting points, although
I take minor exception to certain ones.
My own four -channel interest predates his "Phase One" by several years
since I have previously used a rear
speaker wired similar to the Dynaco
method to improve the sound field. The
present system includes separates across
the board. AR3a speakers (the LST is
planned for the front), Crown International and SWTCo amplifiers, decoders in profusion (Sansui QS -1, EVX44, Metrotec, JVC-CD4, etc.), 2- and
4 -channel tape decks, along with numerous other goodies. All of this tied
together through a self-designed and
built switch panel. I purchase and try
new decoders as they come along. (The
Sony SQD-2020 is on order.)
I gather from Mr. Feldman's article
that the trend will be toward an "all
in one" sort of box with a demise of
the separate decoder. I would not wish
to see that day arrive.
The receiver has not been built, 4channel especially, that will match the
quality and power of a Crown DC -300,
AUDIO
NOVEMBER 1973
THE SONY
SOUND LAB
Even if you can't afford it, you should know about it.
Knowing about a system like this
gives you more than just a hook to
hang your dreams on. It's also a benchmark that the system you have (or the
one you plan to buy) can -be measured
against.
It exists because engineers dream,
too. And because, at Sony, they turn
their dreams nto rea ity.
One dreaned of a turntable whose
mechanical performance would approach an elec-ronic circuit's level of
perfection. The result was the PS -2251,
in which electDnic ci -cui -E perform the
formerly mechanical iunctiors of speed
selection, speed regulat on and pitch
control. The single moving part...the
turntable/servomotor asserrbly.
Other Sort' engineer:. wouldn't settle for anything less titan a tuner with
absolute interference rejection. So they
added to an already interference -free
tuner, a circuit that could cut through
even the most persistent impulse noises
of men and machines.
More dreams: A preamplifier with
the control flexibility of nearly 2,000
precisely repeatable response settings
and precisely 42 levers, meters, knobs
and jacks. A quadraphonic decoder
with dual logic circuits that can make
your system realize the full potential of
four channel SO discs and FM broadcasts, with decoder circuits for other
matrix recordings, and a full complement of quadraphonic monitoring and
control facilities. Plus power amplifiers
so clean that they approach the maximum dynamic range of a live symphony
orchestra while delivering 100 contin-
uous watts of power per channel at all
frequencies from 20 to 20,000 Hz, with
less than 0.1% distortion.
Dreams, once. Realities, today.
And new realities to come. For after
the dream levels of performance are
achieved, our engineers re -scale their
visions, asking: "What if we could adapt
these new techniques, approach these
levels of performance and sophistication, in less costly equipment?"
Some of the answers are on your
Sony dealer's shelf already.
The complete Sony. Sound Lab described
above sells for $2,247.00: PS -2251 turntable,
$349.50; ST -5130 tuner. 5349.50; TA -2000F preamplifier, $579.50; SOD -2020 full logic SO decoder, $229.50; (2) TA -3200F stereo amplifiers,
$369.50 each. All prices suggested retail.
Sony Corporation cl America, 9 West 57th
Street, New York, N.Y. 17019.
SONY
Check No. 56 on Reader Service Card
www.americanradiohistory.com
AmericanRadioHistory.Com
Now that the AT 12S
with genuine
Shibata stylus is here...
all other stereo cartridges
over $50 are obsolete!
Better performance from existing stereo records, and
ideal operation of any CD -4
discrete playback system is
yours when you select an
genuine Shibata tips that permit response
to 45,000 Hz and
above, while minimizing record wear and
audio-technica
offering superb tracking.
Write today for free
literature and list of
audio-technica
dealers
nearest
four channel cartridge.
Now four models,
including the new
AT12S at only $49.95
suggested retail. All with
you.
audio technica®
AUDIO-TECHNICA U.S., INC., Dept. 103A 1655 W. Market Street, Fairlawn, Ohio 44313
Check No. 12 on Reader Service Card
"...Over the years, no company
has offered such a wealth of
little gadgets to gladden the
souls of hi-fi putterers."
HIGH FIDELITY MAGAZINE
PROOF: OUR LOW-PRICED
RECORD -SAVERS.
While everyone else is telling you
how cleaning devices can prolong
your records' life
and improve
your sound, we
just quietly made
them less expensive.
At under $5, our velvet
plush Record Ionizer
wipes out groove noise
Our Professional Groovemaster is something else. Built
like a precision tone arm, its
feather-light touch catches
dust before your needle does.
At under $12.00, you'll hardly
feel the price, either.
or for that matter, a SWTCo Universal
Tiger. A 20 watts per channel receiver
simply will not handle an AR3a.
If the purist (or in my case, HiFi nut)
wants the best, separates is the only way
to go, and this means separate decoders.
This method will permit any change,
modification, up -date or what have you
without regard to form factor, power
requirement, or visual esthetics decreed
by the XYL for her front room.
Yes, my system looks like Fig. 3 on
page 32, only more so, thank goodness.
I can add, use, experiment with any
decoder in any format, in any size without disrupting in any way the remainder
of the system.
I, for one, hope the separate demodulator/decoder is here to stay.
Frank C. Smith
APO San Francisco
From Radio Shack
Dear sir,
We are greatly appreciative of the
excellent reports on Realistic receivers
Len Feldman has written for AUDIokeep 'em coming! There is just one
thing that bugs me: at the end of your
STA- 120 report and the beginning of
your QTA-790 report, you commented
adversely upon a little stock paragraph
on the inside cover of our operational
manuals. I wrote that gem about seven
years ago merely to indicate Radio
Shack's desire to please people via
the sound, the look, the feel, and the
reliability of our equipment as opposed
to mere specs. I have now rewritten
those comments out of fear that the
next time you review us your irritation
will have reached the point of making
a headline (or indeed an entire report)
out of my innocent prose. O the awesome power of the press!
Lewis F. Kornfeld, Jr.
President
Radio Shack
without wiping out
your budget.
Impregnated with
special anti -static
fluid, it extends
record life by eliminating dust.
1=1
I
NJ 9®O
ROBINS INDUSTRIES CORP.
"And if we do have twins, they
will not be named `Woofer' and
Tweeter!' "
COMMACK, N.Y. 11725 (.516) 543-5200
Check No. 50 on Reader Service Card
75 AUSTIN BOULEVARD,
12
AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
NOVEMBER 1973
Have you really heard
four channel sound?
If you were aware
of sound coming from four
loudspeakers,we think the answer is no. The purpose of a loudspeaker is to produce acoustical fields in
your home appropriate for the reproduction of a musical performance. The loudspeakers themselves should not, and cannot, play
the roles of musical instruments. (Their sizes and radiation patterns do not
duplicate those of any single instrument let alone an ensemble of instruments.)
In fact, you shouldn't hear the speakers themselves. If you do hear the sound
coming directly from the speakers, then you are experiencing all the distortions associated with the sound of a complete orchestra emerging from a small box. In four
channel systems (QUA DI, these distortions are even more critical than in stereo, since
localization to point sources behind a listener can be very unnatural and disturbing to the ear.
There are two key factors for excellence in QUAD: 1. The use of DIRECT/REFLECTING®
speakers which, by radiating waves at selected angles to the walls, interact with the room surfaces to produce a spatial pattern like the one which is indicated in the diagram on this page.
With this arrangement, you hear the performance instead of the speakers. Contrast this with
the beaming patterns of direct radiating speakers that cause shrillness, result in localization to
the face of the speakers, and confine the QUAD effect to a small area in the center of the
room. 2. A very close match in the frequency characteristics of the front and rear channels.
This is very important to assure the same musical timbre from all channels. BOSE achieves this match by the SYNCOMTh II Speaker testing computer to an accuracy
that, we believe, is not approached by anyone else in the industry. But there is
even better news about matching. The new BOSE 501 SERIES 11 is designed
specifically to match the new BOSE 901 SERIES II for QUAD operation.
Thus, you can begun with a 501 stereo system and later add on to obtain a 901 front/501 rear QUAD system -- a system that you
must hear in comparison to conventional QUAD!
For information on the BOSE products,
circle your reader
service card
n
or write Dept.OA.
y
Reprints of Dr. Bose's TECHNOLOGY REVIEW articles are available from BOSE for $.50 per copy.
The Mountain, Framingham, Mass. 01701
Check No. 16 on Reader Service Card
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AmericanRadioHistory.Com
Behind The Scenes
Bert Whyte
Iis
THAT TIME of year againautumn in New York-and the
46th Audio Engineering Society
convention begins its four-day run at
the prestigious Waldorf-Astoria. With
the general upswing in the recording
business, this has encouraged more
and more equipment manufacturers
to take exhibit space at the convention,
so there will be scads of interesting
new audio items, which we will report
to you in due time.
Time is indeed a problem in dealing
with audio products. Far too often a
product is announced, or a prototype
shown, and by the time you get a unit
for evaluation, a year may have passed.
As a matter of incidental interest, you
may not be aware that electronics
manufacturers are currently in a terrible
bind for parts. It seems that during the
recent recession most parts vendors
let their inventory position diminish
almost to the vanishing point. Now that
things are booming again, the lead time
on items such as power transistors,
resistors, capacitors, etc. has assumed
incredible proportions. You hear horror
stories such as 40 weeks for "garden
variety" parts, and a year or more wait
for specialty items. One manufacturer
of high -power amplifiers requires a
very fancy capacitor and the vendor of
the part is quoting a mere 2' years
delivery! Needless to say, a great deal
of intricate "wheeling and dealing"
is going on in efforts to circumvent
these situations. It is also obvious that
the small, highly specialized audio
manufacturer, who is usually in a
limited capital position, is particularly
vulnerable in this parts bind. In spite
of all this, most companies seem able
to cope with the situation. Fortunately
too, the traditionally "venturesome"
audio manufacturer has continued his
research programs and we see the fruits
of all this labor at the engineering
conventions. It also appears that the
parts shortage has not deterred "people
with ideas," from entering the audio
business. A case in point is the story
of Mark Levinson Audio Systems, a
Connecticut -based manufacturer of
some very exotic audio products.
I first encountered the company at
the 45th AES convention in Los Angeles
last May. Sharing a demonstration room
with Burwen Laboratories, they were
showing their LNP-2 preamplifier which
drew attention not only because of its
unusual design, but for the rather dazzling specifications which were quoted
and the rather breath -taking price of
$1750.00! As is usually the case, a
brief exposure in a typical demonstration room gives a very superficial
evaluation of a product, but what I
saw and heard of this preamp intrigued
me. I made arrangements to try out
one of these units, and for the past
several months it has been in daily use
in my audio system at home.
Mark Levinson is a very intense,
dedicated young engineer, who is by
far the most rigidly uncompromising
audio purist I have ever met. His
company philosophy and his products
are a reflection of this attitude. As I
have gently pointed out to him, "his
way" is not the way to riches. His
disdain of component parts that are
not of "state of the art" quality is
almost monumental. His immaculately
wired preamp uses teflon -coated,
shielded wire throughout, and one
engineer friend of mine saw this,
snorted, and said "Hell's Bells! Who
needs it? This is aerospace stuff!"
Mebbe so . . but this practice yields
crosstalk of minus 95 dB and relative
immunity to noise pick-up.
.
14
As you can see in the photo of the
unit, it is designed for rack -mounting.
The chassis is brushed black anodized,
and top and bottom plates are secured
with stainless steel Allen screws. All
lettering and index markings on the
front panel are hand -engraved. The
satin -finished aluminum knobs are
large and easy to handle. The LNP-2
preamp is a modular unit. The military
spec, glass -printed mother circuit board
has gold-plated input sockets. These
mate with six Burwen plug-in epoxy
encapsulated UM201 mixing amplifier
modules, which are high gain 7mc
bandwidth operational amplifiers of
extremely low noise
microvolt
20Hz to 20kHz. A seventh plug-in
module is a Burwen VU306 peak VU
detector. There is an eighth input
socket which will accept other optional
special function modules. As you can
see, there are two large Weston VU
meters and the meter function is
controlled by the VU306 peak detector.
Normal VU averaging characteristics
are provided in one switch position.
In another position, the module gives
a 5 microsecond response and will hold
peaks for 2 seconds. The switch position
marked HF + shows + 13 dB @ 20kHz
for slow speed tapes to avoid high frequency saturation. The meters monitor
the record output of the unit. The
preamp has input provisions for phono,
tuner, auxiliary and two tape units.
Main output and two tape outputs are
provided. Cannon connectors are in
parallel with standard phono connectors
for tape in and out and amplifier
output.
Mark uses a regulated plug-in epoxy
encapsulated power supply mounted
in a separate chassis to avoid hum
pick-up. The unit has the usual input
.
.
1
facility switches and mode switches.
In addition it has input level controls,
which are in essence balance controls,
and record output switch so tapes can
be made either in mono or stereo. Zero
VU levels can be adjusted by a pre-set
700 Hz sine wave calibration tone. On
the top right of the preamp is a 0-40
dB gain control switchable in 10 dB
steps to allow maximum S/N ratio
for any input level. There are three
tone controls: 20Hz, + 14 to -8dB in
2dB steps; 5kHz, +3 to -3dB in 1dB
steps; and 20kHz, + 14 to -8dB in 2dB
steps. Noise with these controls is
typically less than 100 dBm (all controls
maximum, less than minus 87 dBm.)
Throughout the preamp, resistors are
1% tolerance metal film. Capacitors are
AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
.
NOVEMBER 1973
Manufacturers often talk and write about
performance specificat ons, particularly their
wide frequency range, as an indication of their
equipment's quality. But: how does this relate
to "listening quality"? Sneaker manufacturers
publish nearly identical specifications but
these are of interest only as theoretical
abstractions, since no one can significantly
relate them to "listening quality."
Bozak Speakers have only one purpose, we
call it the "Bozak Ideal' to recreate your
favorite sounds technically anc musicallyrock or Bach-in all of their subtle detail and
thrilling power. With clean, true -pitch
bass, clearly defined mid -tones and clear,
warm treble.
Bozak's Sonora speaks for itself too!
Designed especially for those with an ear for
superb sound but with limited budget, as well
as space, Sonora has more quality for its size
than any other bookshelf speaker available.
Hear them at your Bozak dealer today. You'll
discover that every Bozak is all Bbzak!
BOZAK, Box 1166, Darien, Conn. 06820
Overseas Export: Elpa Marketing Industries Inc.
New Hlyde Park, N.Y. 11040
It's tough
to compare something
in a class by
itself.
www.americanradiohistory.com
AmericanRadioHistory.Com
either solid tantalum or 1% tolerance
metallized polycarbonate. Potentiometers have conductive plastic elements
and teflon -coated shafts. The input
level controls and the ganged volume
control are calibrated in 1 dB steps
from 0 to -30dB and are guaranteed
to track within 0.1 dB between channels
for virtually identical frequency response and amplitude. On the rear of
the preamp is a Cannon connection
which is for powering a versatile
electronic 'crossover, which is just about
to achieve production status.
For those die-hard advocates of
moving coil phono cartridges such as
the Ortofon, which have problems with
low output, Mark has the JC-1 prepreamp, a John Curl -design six years
in the making, to solve the gain
problem with an astounding equivalent
input noise of -147 dBm.
As I noted earlier, the specifications
on this Mark Levinson preamp were
so spectacular, that I wanted a thorough
check-out on them. Thus, I had some
tests run at a very sophisticated manufacturing facility, where among other
things they had a Hewlett-Packard
Fourier harmonic spectrum analyzer.
On the line inputs to main or record
output, the tracing on the graph was
practically unwavering showing harmonic distortion below 0.001, and this
at odd and even harmonics way on out.
The same test on the phono input
showed some 0.003 to 0.004 spikes at
odd harmonics, but we later learned
this test was invalid because the input
gain control was set at the 40 dB point,
a setting that would almost never be
used in any normal circumstances. I
next visited the Mark Levinson labs in
Connecticut and ran through every
test with Mark. He has fine equipment
including the well-known Radford
low -distortion signal generator, HewlettPackard voltmeter and digital voltmeter,
scopes, etc.
We checked every standard parameter, and all met or exceeded the
claimed specifications. Thus the tracking
between pots was verified at 0.1 dB.
The frequency response bettered the
listed ± 3 dB, 0.5 Hz to .5 MHz and
0.1 dB, 5 Hz to 100 kHz. THD was
less than 0.005%, d.c. to 10 kHz, 0.02 at
20 kHz. S/N ratio of the phono measured a fabulous 86 dB below 10 millivolts input at 1 kHz (inputs shorted),
and the line measured an incredible
minus 134 dB! The RIAA curve was
accurate to within 0.4 dB from 20 Hz to
15 kHz. Phono overload was at the
lofty figure of 250 millivolts, better by
at least 50 millivolts than any other
preamp I am familiar with.
3 of the Worai
Best Sdlers!
...
Okay
so everything checked out
with this super unit. The big questions
is any preamp worth this kind
are
of money . . and what did it sound
like? Can any difference be detected
between this unit and the lesser -priced
preamps on the market?
As far as money is concerned, this
is a preamp designed to be used as a
laboratory tool; it is a professional
instrument in the truest sense of that
overworked word. The unit is guaranteed for 5 years, parts and labor free
of charge. If your inclinations are to
superb specs with maximum repeatability and reliability and your pocketbook can absorb the shock, it certainly
can be regarded as an investment. As
to the sound, it does one thing superbly
well
phono and line noise simply
are inaudible and cease to be a factor.
It sounds measurably cleaner in the
phono listening, perhaps because of the
high overload characteristics and the
high velocities encountered on today's
discs. The transient response is razor
sharp in line or phono, and the bass
is unusually solid and clean. Yes, there
are audible differences, subtle to be
true, and admittedly something you
have to listen for, but if you are one
of the puristelite to which such subtleties
are important this preamp is unquesmonetary considerations
tionably
aside
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Check No. 66 on Reader Service Card
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AmericanRadioHistory.Com
...
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AUDIO
NOVEMBER 1973
Incredible.
Sorry, but when it comes to our
new Phase Linear 4000, modesty
fails us. How else would you
describe a preamplifier that actually:
Puts back in what recording
studios take out.
Restores dynamics lost in
recording to closely approximate
the original.
Vanishes into virtual inaudibility all
hum, noise and hiss inherent
in most tapes, records, and
FM broadcasts.
Lets your music (at last) reach
a life -like level where cymbals
sound like cymbals, kettle drums
like kettle drums.
Lets you ... for the first time ..
hear your music from a
silent background.
Since its introduction fo lows the
Phase Linear 700 and 400 power
amps, the 4000 pre -amp had to be
good. Consider these features:
The Peak Unlimiter
To prevent overload in recording
equipment, studios today "peak
limit" high-level explosive transients
of the source material. Incorporated
in the Phase Linear 4000 is a
highly -advanced circuit that reads
peak limiting, immediately routes
the signal through a lead network,
and restores dynamics lost in
recording to closely approximate
the original.
The Downward Expander
Gain riding, a recording technique
used to improve low level signal to
noise on phonograph discs,
unfortunately compresses dynamic
range that would otherwise be
available. The 4000 senses when
gain riding has been used and
immediately expands the dynamics
reciprocally downward to precisely
the intended level.
The AutoCorrelator
The advanced Autocorrelation
Noise Reduction System in the
4000 makes record/tape hiss and
FM broadcast noise virtually vanish
... without effecting musical content
of the source material. Over-all noise
reduction is -10 dB from 20 Hz to
20 kHz. Your music comes from a
background that is silent.
Plus...
...
the 4000 is an advanced stereo
preamp with SO* and Phase Linear
differential logic ... its Active
Equalizer gives you a truly flat energy
distribution over the full audio
spectrum ... completely passive,
independent Step -Tone Controls
allow precise tailoring of the music
to your listening environment.
It is, in a word, incredible. Ask your
dealer for an audition.
PHASE LINEAR 4000 SPECIFICATIONS
Total Distortion: Less than .25%.
Typically .02%.
Total Noise: High level: 95 dB below full
output. Phono: 82 dB below full output.
Tone Controls: Bass: Monotonically
increasing and decreasing, dual hinge
points, ± 8 dB @ 20 Hz. Hinge points
switch selectable beginning at 40 Hz
or 150 Hz. Treble: Monotonically
increasing and decreasing, dual hinge
points, ± 8 dB @ 20 kHz. Hinge points
switch selectable beginning at 2 kHz
and 8 kHz.
Active Equalizer: 6 dB/octave
bo^,,s
...
below 50 Hz.
Peak Unlimiter: (Nominal peak unlimit
rate attack threshold, front panel
variable) .5 dB/micro second for + 6 dB
peak unlimited operation.
Downward Expander: Downward
expansion commences at -35 dB.
Ultimate limit is -41 dB. Unlimiter
window is 35 dB wide, upper and lower
thresholds are simultaneously variable.
Auto Correlator (Noise Reduction
Systems): High frequency noise reduction commences at 2 kHz and is 3 dB,
reaching 10 dB from 4 kHz to 20 kHz.
Weighted overall noise reduction is
-10 dB
from 20 Hz to 20 kHz.
Size: 19" x 7" x
Price: $599
10"-Weight:
18 lbs.
Cabinet: $37
Warranty: Three years, parts and labor.
Ayne Yòmait 4000
Check No. 40 on Reader Service Card
SO
is a trademark of CBS Labs, Inc.
THE POWERFUL DIFFERENCE
PHASE LINEAR CORPORATION, P.O. BOX 549, EDMONDS, WASHINGTON 98020
www.americanradiohistory.com
AmericanRadioHistory.Com
Editor's Review
celebrating its
25th anniversary this year and its 46th convention
was held September 10 through 13 at the WaldorfAstoria in New York City. Some 14 technical sessions
were held, and the New York Section's presentation,
"Look What They've Done to My Song, Ma!" was
easily the most popular, with more than 750 people
attending each of the two presentations. Producers
Irving Joel, Al Grundy, and John Woram gave those
in attendance a "listen -to and a look at distant past,
recent past, and current attempts by the recording
industry to capture and create the elusive impact
of music." More than 40 selections were played,
from a 1904 Victor recording of Sousa's Band, with
Herbert Clarke conducting, to current releases by
artists such as the Beatles and the Boston Symphony.
Exhibitors took one entire ballroom on the third
floor, adjacent to the technical sessions rooms, and
most of the fifth floor. One of the most interesting
exhibits was the museum of early sound recording
equipment, which was gathered by John T. Mullin.
Presented for the first time at the 45th Convention, in
Los Angeles, the museum contained examples of various stages in the development of recording equipment
over the last 80 years.
At the Awards Banquet, C. G. McProud, Audio's
former editor and publisher, was the featured speaker.
In addition to publishing the letters from Frank Sherry
and C. J. LeBel which led to the formation of the
Society, McProud also published papers presented at
the early New York meetings. The A.E.S. Journal, of
course, began publication in January 1953, and
through the years Audio has been pleased to be able
1HE AUDIO ENGINEERING SOCIETY is
Erik Madsen
to reprint many of these important papers. In 1952,
McProud became President of the Society.
Award recipients in this Silver Anniversary year
included Erik R. Madsen, who was presented the Silver Medal, formerly known as the Emile Berliner
Award; James White, who received the first Publication Award for his paper, "Mechanical Playback
Losses and the Design of Wideband Phonograph
Pickups," JAES, Vol. 20, No. 4, and Donald W.
Powers, who received the Medal Award, which is
given annually to a person who has significantly helped advance the Society.
Honorary Memberships were presented to William
S. Bachman, Murray G. Crosby, and Cyril W. Harris.
A Fellow Award was presented to Edward Tatnall
Canby, Associate Editor of this publication, "for his
writing over the years reminding us that music is what
the audio industry is all about." Also receiving Fellow
Awards were Roy F. Allison, Richard S. Burwen,
C. Robert Fine, Irving L. Joel, Arnold Schwartz, and
Takeo Shiga.
Expanded Speaker Tests
This month a new name will be found at the end
of our speaker system tests, that of Richard C. Heyser.
Mr. Heyser is a member of the Editorial Board of the
Journal of the Audio Engineering Society, in which
several of his papers have appeared. He has been
actively involved with test procedures for speakers
for many years and his name will be familiar, I'm
certain, to most speaker designers. An article by Mr.
Heyser, explaining our new test methods, begins on
E.P.
page 20.
C. G.
McProud
AUDIO
18
www.americanradiohistory.com
AmericanRadioHistory.Com
NOVEMBER 1973
The best of both worlds-
PICKERING'S STATE-OF-THE-ART
CARTRIDGES...
Pickering has done it again! In 1957-the first American -made magnetic
stereo cartridge that helped build the industry was a Pickering. Now-in 1973
-the first American -made discrete, 4 -channel cartridge that will change the
world's listening is a Pickering. Today, Pickering invites you to enjoy the best
of the world of your choice.
For the world of
STEREO
XV -15/1200E
For the world of
DISCRETE 4-CHANNELUV-15/24000
Designed for use with all stereo
and four -channel derived compatible systems.
"PRECISION" is the one word that
best characterizes the extraordinàry quaJty of the new Pickering
XV -15/1200E cartridge, the culmination of Pickering's 25 years in
contributing important technological advances to the manufacture
of magnetic cartridges. We sincerely feel that the 1200E is the
furthest advance achievable today
-and perhaps in the foreseeable
future in stereo cartridge design
and performance. Its exceptional
ability to pick up all the material
recorded at the lightest possible
tracking forces make it totally
unique and superior. This cartridge
is for the sophisticate-one who
possesses components of such superlative quality that the superiority
of the XV -15/1200E is a require-
Designed and engineered
specifically for playback
of discrete recordings.
The introduction of the
discrete 4 -channel system
required a completely new
QUADRAHEDRAL
cartridge that could not
only faithfully reproduce the 20 Hz to
20 kHz AM signals, but also the 30 kHz
FM modulated signals. The result is the
-
Pickering UV -15/24000 discrete
-
ment.
And all of Pickering's exhaustive
testing shows that the 1200E
is
superior in the flatness of its frequency response and channel
separation in comparison to competitive cartridges.
SPECIFICATIONS
Frequency Response: 10 Hz to 30 kHz
Channel Separation,
Nominal:
Tracking Force:
Nominal Output:
Stylus Tip:
35 dB
x
SPECIFICATIONS
Frequency Response':
10-50,000 Hz
Channel Separation:
35 db
Tracking Force':
Output,:
Stylus:
1-3 grams
3.8 my ±2 dB
Quadrahedral
Notes:
1. Recommended by manufacturer for optimum performance.
2. When the cartridge is terminated in the recommended load of 100K ohms and 100 PF.
3. Output with reference to 5.5 cm/sec record
gram, +1/2 gram,
-1/4 gram.
4.4 my
3/4
0.0002"
4-
channel cartridge, which represents a
new level in the state of the art. It consists of a completely redesigned cartridge and a new high performance
stylus assembly, the QuadrahedralTM,
which was specially developed for this
application, and features a revolutionary new diamond stylus. The UV -15/
2400Q performs in a superior manner
by every measurable test, and is capable of satisfying all the technical and
aesthetic requirements for playback of
all the material recorded on both discrete and stereo disks. Moreover, its
stylus is so designed that it not only
perfectly reproduces the music recorded, but also reduces record wear.
velocity.
0.0007"
The right Pickering cartridge for your equipment is the best cartridge money can buy.
PICKERING
For further information write Pickering & Co., Inc.,
Dept. F, 101 Sunnyside Boulevard, Plainview, New York 11803
"for those who can Ihearl the difference"
Check No. 41 on Reader Service Card
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AmericanRadioHistory.Com
BREAKTHROUGH
IN
SPEAKER TESTING
Richard C. Heyser
adding several loudspeaker testing procedures
in order to provide additional data about speakers.
While these tests will be laboratory tests simply because
no two listening situations are identical, we have attempted to
bring these tests as closely as possible in line with the actual
conditions of use. While researchers do not have a uniform
opinion about the relative value of some of these tests, these
new methods of presentation are a step forward in providing
additional information about the properties and characteristics
of speakers. The purpose of this article is to introduce these
new tests, several of which have previously appeared only in
learned journals, and to explore their meaning, as well as to
review the other tests which we have been using.
AUDIO is
Frequency Response
The frequency response of a speaker is a measurement of a
speaker's ability to reproduce constant sound pressure of any
pitch component, from lowest to highest, from constant electrical stimulus. It will continue to be our standard practice to
plot the relative magnitude of sound pressure for each frequency component.
Frequency response, like that of an electrical network, also
has a phase response as well as an amplitude response for
each pitch component, and this phase response is associated
with "when" a sound arrives at your ears after the application
of an electrical signal.
We all use the different "whens" of arrival to distinguish
between direct and reflected sound in evaluating the spaciousness of a room and to locate sound sources. These abilities are
based on the constant speed of sound, but imagine what would
happen if the speed of sound depended on pitch. An instrument's fundamentals and harmonics would all be there, but
they wouldn't arrive together as we normally expect. Some
speakers do exhibit delays like this, and these are closely
associated with phase response.
The exact relationship of phase and amplitude response is
quite complicated and still open to final interpretation. However, it can be stated that two speakers with exactly the same
amplitude response will not produce the same sound unless
they also have the same phase response and that a speaker
with a smoother amplitude response than a second will not
reproduce more accurate sound unless the phase response is
also well behaved. Highly important to a speaker's ability to
produce accurate sound, when it has been properly equalized,
that of minimum phase change. A minimum phase change
speaker is one which, when all amplitude response variations
are removed by conventional resistance, capacitance, and
inductance networks, has the minimum possible phase shift
over the frequency spectrum. It is then like the proverbial
piece of wire in its handling of signals. Conventional tone
control equalization for balancing the amplitude response will
also automatically balance the phase response for a minimum
phase loudspeaker.
We will identify those regions of the frequency spectrum of
each tested speaker where non -minimum phase reproduction
occurs for direct sound. We must stress that this does not mean
that a minimum phase speaker will automatically produce
more accurate amplitude response than a non -minimum phase
speaker. However, a non -minimum phase speaker will usually
exhibit frequency response difficulties which can be associated
with time delay effects which, in turn, cannot be corrected
with conventional passive equalization.
Basic to our presentation of both amplitude and phase
response is a spectrum analyzer, a Pro bescope Model SS -100,
specially modified to become an adjustable bandwidth tracking
filter which can be phase locked to any signal from 10 Hz to
100 kHz. The standard test setup uses a -in. Hewlett-Packard
mic on axis one meter from the speaker being tested. A glide
tone is fed to the speaker, and the tracking filter, tuned to the
frequency of the glide tone, picks up the direct sound as
received by the mic. Since the frequency bandwidth of the
tracking filter is narrow and its center frequency changes
rapidly to follow the glide tone, only direct sound is passed
for measurement because reverberant sound will not have
arrived before the filter changes frequency. Thus the amplitude
response measured is anechoic. Phase response is obtained in
a similar manner using a continuously variable phase shifter
which permits either relative or absolute phase measurements.
To take into account the coupling of a speaker and room,
without placing undue emphasis on room characteristics, a
second measurement of amplitude is made using a wider
bandwidth, or time window, so that early reflections from
floor, ceiling, and-where appropriate-walls are included.
Tests below 100 Hz will not be performed here since the longer
wavelengths of those lower frequencies would require inclusion
of more room reverberation characteristics than are of interest.
The distance for this test will be three meters on axis, one
meter above the floor, to approximate the usual listening
is
20
1
AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
NOVEMBER 1973
Picture your system on tile tube.
The Heathkit AD -1013 Audio -Scope --seeing is believing
A prG essionM-grade oscilloscope gnat visually mon tors stereo and 4 -channel discrete and rrlatrixed systems.
Now you actuary can see channel seoaraton, phasir.ç,
relative signal strengths, multipath rGeception, center tuning of -eceivers and tuners, and mo-e. Ane in easy-,c build k t form yam save virtually hurdieds of dollars o er
what you would normally pay for an instrument this te liable and versati e.
provides a convenient means cf setting up and checking
your a -channel c-r 2 -channel s:ereo system. Front pari&
controls are pro"ided for frequency selection of the audio oscillator as wel: as controlling the amplitude of the
generated'signaL Outputs fron the audio oscillator are
located en both front and rear panels. Output voltage
will rot vary with frequency change.
Cabinet -matched to the Heathkit AR -1500 Receiver,
for obvious reasons, the AD -1013 nevertheless looks
great ane works great with an receiver or tuner having
multiplex outputs.
Only the Heathkit Audio -Scope gives you trigger=_{
sweep for a stable, jitter -free trace N-ithout constant readjustment, Inputs are provided on tte rear panel of ha
Audio -Scope for Left -Front, Left -Back. Right -Front, Right Back, and Multif_attn. Any of these inputs can be switched
and observed or: the cathode ray soreen, indepenien:le
or in combination.
In acdition, a front panel input is p-ovidec for obsea.ing arty external source, permitting you to use the AC 1013 as a conventional oscilloscope for cneckirg cut
malfunctions in arious stages of you- tape equigmen-,
receives, amplifier, tuner, turntable. etc. A built-in incependent 20 Hz to 20 kHz low distortion audio oscillator
You can build the Heathkit Audio -Scope even if you
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to 20 kHz. Voltage Live: 2 mV to 3 volts (rns) (-tenable). Output VariNSion:.25 dB 20 Hz te 20 kHz. Output tmped
(front panel ja.k); 4Fproximztety 6000. ;vibrator Voltage: 1.0 voit P -P `a á: iota! tt-monic 'Di ttortiun: 1% or less. REAR PANEL
esctRator Outpu: IM21dance: 60G0?, MultiaatO input (Scope Horiznn:zd and Scope Vertical:
Sensitiv.te: 25 nti Pe/c-ri. input Impedance_ 13e id?. Left Fron:, RI -t
Front, Let Back and Right Deck inputs: SensRh4ty: 25 rrVP-Pier. inpr.t
tnipedanc`:: 100ko. Frequency Response: 5 14z
200 tOz,
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GENERAL
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Requirement: 120 or -240 volts AC, 50/60 Hz, _15 watts with no accessary
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State
Mail order prices;
Zip
F.O.B. factory.
HF-276
The peaks indicate
position. If listening tests show that off-axis positions are hiss, stand out more than they should.
cause ringing at a
actually
can
if
extreme
and
resonances
will
arrangements
speaker
these
for
stereo
effects,
preferred
at
lower frequencies.
hangover
and
high
frequency
discernible
be used for this test.
a relatively narrow
over
in
amplitude
dips
sharp
Sudden
2.
The
and
Figs.
in
is
shown
of
these
data
formats
The
of much
amplitude response, identical to what is usually called the frequency range are often due to interference effects room.
in
a
sound
with
natural
occurring
as
those
type
the
same
The
in
decibels.
plotted
will
still
be
frequency response,
other
but
sound,
for
direct
inaudible
relatively
may
be
They
phase response is plotted in electrical degrees relative to a
frequency
same
the
have
not
may
radiation
of
angles
polar
mic
to
from
delay
air
path
which
the
in
pure transmission
for these frespeaker is removed. The convention chosen for measurement dip. The effect could then be a lateral shift
material in a
program
stereo
for
listen
when
you
quencies
the
positive
to
applied
voltage
a
positive
of phase shift is that
may not be
effects
interference
Such
room.
live
relatively
(usually red) speaker terminal will produce an increase in
reflection
room
on
which
depend
speakers
in
those
noticeable
toward
moves
cone
speaker
the
sound pressure and assumes
on direct
rely
heavily
which
speakers
for
avoided
to
be
are
but
the listener with this polarity.
imagery.
or
quadraphonic
stereo
for
sound
traditional
in
the
done
is
curve
amplitude
Evaluation of the
The other major effect of amplitude response on reproducmanner. Sharp peaks of more than 3 dB generally are more
tion
of direct sound-change of timbre-can be estimated by
traveling
sounds
because
size,
the
same
obtrusive than dips of
average values of
two slightly different distances can cancel by any amount even visually smoothing a curve through the
relative response
note
the
is
to
thumb
of
rule
One
an
response.
to
give
reinforce
cannot
but
to total null at one frequency
(65 Hz), and
below
two
octaves
Hz),
C
(262
middle
intensity greater than their sum. Such peaks will generally around
is down more than
speaker
If
the
Hz).
(4186
above
octaves
four
and
tape
pops
record
as
noises,
such
tend to make background
about 3 dB at 65 Hz, it stands a chance of sounding "thin."
.10
The shape of the speaker's low frequency roll off and your
pre -amp's tone control curves can indicate whether you can
bring this up to a full bodied bass without incurring a bump
of more than 3 dB at some intermediate frequency, such as
A, at 110 Hz.
A look four octaves above middle C to C, will indicate
whether the principal musical partials of most instruments
will be reproduced fully. Difficulties in this range will usually
MR
indicate a noticeable change in timbre. If the high end is
rolling off, it will be dull, while a rise in response usually
betokens brightness. The use of tone control and speaker
curves also applies here.
M
10
!00
I0
Im
1
7\\
110'
EREQUENCIN
Fig.
1
R
-Anechoic amplitude and phase response.
30
20
100
50
200
500
FREQUENCY
Fig.
IN
10
50
100
200
Nt
2-Amplitude response including early reflections.
)14
Fig.
100
IOR
100
3-Polar
response.
Polar Energy Response
The success of good stereo and quadraphonic imagery
depends largely on how much and what quality of sound is
radiated at different horizontal angles. Since it is impractical
to publish response curves for every possible angle and frequency, a polar plot will be made which, together with the
frequency response, can give a reasonable feel for the dispersion you can expect in your listening environment. The
basic tdst setup is much the same as that used for the amplitude
and phase response tests except that a specially calibrated
motor is used to turn the speaker on its axis and to indicate
the relative angle. All fundamental frequencies, from 20 Hz to
20 kHz, are measured with constant input, and the total sound
energy in this band is plotted as a continuous function of angle.
The polar plot is made under the assumption that speaker
directivity becomes more prominent with increasing frequency.
Our plot is made on an equal frequency basis and means that
the higher frequency variations show more prominently in
this plot. Experiments using both an equal frequency basis and
an equal octave basis have shown little significant difference
in most speaker polar responses. The choice of an equal
frequency basis is made because of its listening relationship
with the speaker's reproduction of white noise.
A typical polar plot is shown in Fig. 3, looking down on the
speaker from above. The general meaning of this speaker's
polar response is that you can expect rather uniform sound
anywhere within the dashed line from A, to A, The polar
plot also warns us that there is a strong "finger" of response
at position B, where high frequencies are more prominent
than at C and D. However, since the overall level at B is
about the same as at A, the sound at B is probably well balanced and quite listenable. The sound at E is down overall
and because lower frequencies tend toward less directivity,
this position's sound will probably be bass heavy.
AUDIO
24
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AmericanRadioHistory.Com
NOVEMBER 1973
I bought a Marantz 4 channel
receiver because I refuse to be
stuck with an electronic antique.
Not one to tolerate obsolescence (planned or un-
planned), I considered
the stereo vs. 4-channel
question carefully, then purchased
a Marantz receiver for three compelling reasons.
One. Marantz has Dual Power. This means
you get full power of four discrete amplifiers working
all the time. When you're listening to regular 2 -channel
tapes and records you can combine the power of all
four channels into the front speakers. This means
even if you're not ready to commit yourself to a complete 4 -channel system, you can buy Marantz now
and when you get the other two speakers just flip a
switch. You have 4 -channel. Meanwhile, you're not
compromising 2 -channel because you're getting more
than twice the power for super stereo.
Reason number two. Marantz receivers feature the exclusive snap -in snap -out adaptability to
any 4 -channel matrix decoder. This means that your
Marantz stereo will never be made obsolete
by any future 4 -channel technology
because the Marantz snap -in SQ*
module is designed to keep up with
the changing state of the art. What's
Reason number three. Marantz receivers, from
the Model 4230 up, feature built-in Dolby** noise
reduction to bring you the quietest FM reception
ever. And you can switch the built-in Dolby into your
tape deck for noise -free, no -hiss recording from any
source. A real Marantz exclusive.
I chose the Marantz Model 4270 because it
suits my needs perfectly. It delivers 140 watts continuous power with under 0.3% distortion. And it's
literally loaded with features. However, your requirements may be more modest than mine. In which case
you can own the Marantz Model 4220 which delivers
40 watts with Dual Power. Or you can go all the way
and get the Marantz Model 4300 with 200 watts. It is
the very best. Choose from five Marantz 4-channel
receivers from $299 to $899.95.
The point to remember is this whichever
model Marantz 4-channel receiver you do buy, you
can buy it today without worrying about its being
obsolete tomorrow. Look over the Marantz line of
superb quality receivers, compo-
more, Marantz receivers have
Vari -Matrix- a built-in circuit that
-
nents and speaker systems at
your Marantz dealer. You'll find
him listed in the Yellow Pages.
Think forward. Think Marantz.
mlartamitig
sound better.
We
4 -channel sound
from any stereo source (including
your stereo records and tapes)
and will also decode any matrix
encoded 4 channel disc or
FM broadcast.
will synthesize
'SQ
Is a trademark of Columbia
Broadcasting System, Inc.
TM Dolby Labs. Inc
©1973 Maranta Co., Inc., a subsidiary of SuperscopeInc., P.O. Box 99A Sun Valley, Calif. 91352. In Europe Superscope Europe, SA. Brussels,
Belgium.
Available in Canada. Prices and models subject to change without notice. Consult the Yellow Pages for your nearest Mamma dealer. Send
for free catalog.
Check No. 43 on Reader Service Card
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The polar plot is made without reflected sound, and if your
room were anechoic, it would tell you how to balance your
system. However, we don't listen in anechoic chambers and
here is where your listening room comes into the picture. If
you have a hard wall, such as wood paneling or plaster, behind
the speaker, as indicated by W, you can expect a strong
reflection from the response of the back finger, F. This is fine
if you want to use reflected sound to augment stereo imagery,
but the polar plot shows that the nonsymmetry of the back
lobes will tend to move sound over to the left for this speaker.
If you want strong imagery of violins and brightness on the
left, use this speaker in front of a hard surface, but don't
expect balance on the right channel. By deciding where a
speaker will be placed in relation to reflecting surfaces in your
listening room, you can spot trends of reproduction and possible trouble areas. There are other considerations in choosing
a speaker, but the polar energy response is one of the few you
can tie to your listening room.
Harmonic Distortion
We measure harmonic distortion by using a fixed frequency
sine wave and plotting the second and third harmonic output
as a percentage of electrical drive power. The test signals are
the equivalent of pure flute tones with no harmonic structure
of their own. The three test frequencies are: E, = 41.2 Hz,
corresponding to the lowest fundamental normally in musical
material and the lowest tone in the usual range of the biggest
systems; A, = 110 Hz, well up in the musical spectrum and
within the usual range of the smaller systems, and A. = 440
Hz, A above middle C and a reference pitch generally known
while also at or near the crossover frequency in many systems,
thus a spot where trouble can easily take place.
The second harmonics are: E2 = 82.4 Hz, A, = 220 Hz, and
A5 = 880 Hz respectively, while the third harmonics are extremely close to their musical fifths: B2 = 123.5 Hz; E4 = 330
Hz, and E, = 1320 Hz. These tones not only encompass the
lowest four octaves where distortion is most prevalent but can
be meaningfully related to sounds with a conventional musical
basis. The second harmonic distortion is indicative of gap
misalignment and field nonuniformity, and third harmonic
100
SD
Iw
70
A4 SPL IN dB
3RD
_a
-
2ND
0
3R0 -
-
2ND
E
--
41.2
=
A2=
2N0A5
110
3R0=E6
A4=440
10
20
30
POWER IN dBm
0.01
0.1
1
POWER ,N WATTS
Fig.
4-Harmonic distortion.
10
distortion is tied to a voice coil driving out of the linear region
of the gap or otherwise bottoming out. Higher order harmonics are seldom found unless physical deformation occurs,
which is usually audible as a buzzing or a similar effect. The
use of drive power will give you some idea of how much
amplifier you need before the speaker becomes sonically
improper for steady signals.
Figure 4 is a typical plot for harmonic distortion. The vertical axis is the percentage of distortion of each partial. The
horizontal axis is amplifier drive power in both dBm, which
is a decibel power ratio above one milliwatt, and its equivalent
in watts. Thus one watt is +30 dBm. This power level is not
the actual volt-amperes delivered to the speaker, but is the
level which a constant voltage amplifier would deliver to a
resistor with a value equal to the rated speaker impedance.
This is done so as to be more consistent with the rated capabilities of amplifiers.
There are three sets of curves, one for each test frequency.
Generally the lowest pitched test tone will have the highest
distortion. For the example shown, a one -watt level of the
tone A, will produce 0.8% A, and 0.6% E, as additional acoustic
outputs. A low organ pedal note of E, will at the same drive
produce 1.5% E2 and 2% B2. Of course the acoustical output at
E, is less than A, at this electrical drive power because, as
indicated in Fig. 1, the speaker is rolling off. If you were to
use full bass boost available on many pre -amplifiers to bring
up the pedal note, you might be able to add 12 dB drive to
E, relative to A,. Unfortunately, this would take you from
30 dBm to 42 dBm and the organ pedal note would now have
10% E, and 15% B, as distortion partials. This note might
produce impressive sound pressure in your room but is no
longer musically accurate.
The ratio of third -to -second harmonic distortion is a crude
estimate of driver capability. The speaker shown is running out
of steam at both A, and E, for power levels above 10 watts
as shown by the pulling away of third above second harmonic
distortion. A smooth increase of second -harmonic distortion
with level is usually a satisfactory indication, but sudden breaks
in the curve may indicate non-linear suspension or misalignment of the driver.
Before condemning a speaker for bad distortion, it is necessary to know what sound pressure level (SPL) is actually
produced at each fundamental pitch component. One watt into
some speakers can be a pleasant level while the same power
into another speaker can break both windows and leases. An
intensity level of 1 watt per square centimeter corresponds
to 160 dB SPL for a plane wave of sound. If one watt of
acoustic power were radiated uniformly from a point source,
the intensity level one meter away (which is our test distance)
would be 109 dB if we approximate the spherical wavefront
with a flat wavefront. This is a very high level and above the
capability of some speakers.
For distortion SPL comparisons, measurement is made of
the speaker power required to produce 90 dB one meter on
axis. This is rather loud but within the capability of almost
every speaker system and corresponds to an omnidirectional
source of about 11 milliwatts or 11 dBm. The electrical power
required to produce this level for each fundamental will be
shown as bars drawn through the corresponding harmonics,
as shown in Fig. 4. This lets you convert from amplifier power
level to the sound pressure level in decibels by sliding the
curves sideways until the bars line up with each other and
lie over the 90 dB SPL value.
You can use these data in several ways. First, the relative
distortion produced as you equalize the speaker for flat output
from E, through A, is immediately apparent. Thus for our
example a 90 dB level at A, now has low distortion down to
A, but enormous distortion at E,. Conclusion: If you like true
AUDIO
26
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AmericanRadioHistory.Com
NOVEMBER 1973
pipe organ sound, you probably should not consider buying
this speaker.
The second way you can use these data is to find out how
much amplifier power is required to produce the level and
quality of sound you prefer. For example, the unequalized
speaker of Fig. 4 will show audible distress for single low and
mid bass sine waves at about 20 watt level. Composite material
with many partials will probably gobble up many times that
level before you hear the speaker giving up, so a 60 watt
amplifier might bottom out before you note speaker distress
at SPL's as high as 100 dB.
Intermodulation Distortion
Speakers also suffer from intermodulation distortion. This
occurs when one signal is modified by another because they
share the same driver. Intermodulation can occur due to either
transfer function nonlinearity, of the same nature as that
producing harmonic distortion, or relative motion of the
driver causing a Doppler "warbling" of one signal by another.
Since single speakers in a system usually do not cover the
entire frequency spectrum, it is not possible to use conventional
amplifier practice with tones of 60 and 6000 Hz or any two
tones rigidly fixed in frequency. The greatest problem occurs
in the bass driver and is the effect of very low frequencies on
higher frequencies. Two test tones of equal electrical drive
level are used, 41.2 Hz, corresponding to E,, and either 440 Hz
or one half octave below the woofer crossover frequency,
whichever is lower. Sidebands about the higher frequency due
to 41 Hz are measured and the total sideband energy as a
percentage of the energy at the higher frequency is presented
at one or more electrical power levels.
An example of what this means is shown in Fig. 5. The
signal output in the vicinity of 440 Hz is shown along with
the intermodulation products due to 41 Hz. The level at 440 Hz
is acoustically measured prior to the addition of 41 Hz and
used as reference. Then 41 Hz is added at the same electrical
drive level as 440 Hz and the pressure magnitude of each
sideband is measured. The total energy in the sidebands is
calculated and then presented as a percentage of the unmodulated 440 Hz. This is a one -number power measurement which
is not suitable for distinguishing frequency modulation from
amplitude modulation, and equal electrical drive power for
each frequency is used to provide comparison for cleanness
of sound when driven from a "flat" program source.
Certain special cases may arise when other intermodulation
tests need to be performed. One example might be the case
where an overly compliant woofer may badly wobble in and
out of the linear gap region due to subsonic signals from an
amplifier when bad record warp exists. While this is not
directly the fault of speaker manufacture, it can give sonic
coloration and some measure of this is made.
The guidelines for evaluation of distortion measurements are
simple: The better speaker will have lower distortion at a
given sound pressure level.
Signal Suppression Test
We know that most speakers can handle music and voice
at power levels approaching the peak clipping capability of
even super power amplifiers, yet if we try a sine wave at
what we think these crescendo levels to be, we may char the
speaker. We have already outlined two tests using sine waves,
harmonic and intermodulation distortion. This third distortion
test is intended to disclose how well musical crescendos may be
handled by a speaker.
The concept behind this test is that the highest level signals
which you normally ask a speaker to reproduce, such as cymbal
crashes, traps, and even the human voice, have a high peak -to average intensity ratio. A measure of a speaker's ability to
handle these is made by the amount of intermodulation disAUDIO
tortion produced on a moderate signal by a random crescendo
with peak -power levels approaching 1000 times (30 dB) the
signal to be tested. That may appear to be an unrealistically
high ratio but experience on live sounds picked up by a wide
range condenser mic shows this ratio is not unusual.
Two test signals are used for this measurement. The first
is a flute -type tone with a musical basis, such as 440 Hz. The
second is white noise, which treats all frequencies uniformly
and is not only reproducible in any laboratory but is a good
all-around representation of many sound processes.
When random noise modulates a tone, it produces side bands about that tone. The sonic effect is random wobbling
of the tone's pitch and amplitude-sort of a combined
vibrato and tremulo. What we are trying to measure is how
much effect is produced on regular program material by a
sonic outburst from an independent signal of higher level.
We do this by measuring how much energy in the flute tone is
spread into sidebands by the noise burst, by use of a very
narrow bandwidth filter before and during the time the
noise is applied. The level at which one decibel suppression
of the tone occurs in a Hz band is used as the indication
of power-handling capability when the average noise is 20
dB higher than the average sine wave power. The peak noise
voltage (three sigma)* across the speaker terminals is then
used to indicate the amplifier capability to drive the test
speaker to this level.
This test is strictly an indication of how inner musical
voices are modified by loud random signals and is not a
direct measure of the speaker "flatting out" on the loud
signals, which is presently determined by looking at the mic
pick-up with an oscilloscope.
1
Transient Response
What we mean by transient response is the ability to
produce pressure wavefronts which accurately follow electrical
input as a function of time. This is the "clock on the wall"
counterpart of the frequency response. Just as the sine wave
is the basic signal for determining frequency response, the
basic signal for determining transient response is the impulse, a sudden sharp momentary release of energy which
should produce a sharp sound ordinarily described as a
"crack." A typical transient response of a speaker is shown
in Fig. 6.
Figure 7 is a computer -based plot of the time spread of
sound intensity derived from the impulse response in Fig. 6.
The vertical axis is relative sound intensity in decibels and
the horizontal axis is time in milliseconds. This plot shows
the actual arrival times of signal energy components relative
to the times they should have arrived in order to constitute
PO
P-1
PI
P-2
P2
399
440
481
FREQUENCY
-V
i
t
522
563
IN Hz
IP.2I2+ (P_1)20(P1)2+1P2)20 (P3)2
x 100
PO
Fig.
5-Method of calculating
NOVEMBER 1973
IM distortion.
27
www.americanradiohistory.com
AmericanRadioHistory.Com
perfect reproduction for all components in the frequency
span measured. If a woofer woofs or a tweeter tweets at a
later time than optimum, this will show as some form of
energy spread with time.
A speaker which has perfect reproduction of every signal
component in the tested frequency range will have the signal
energy hump shown in Fig. 8. This tells us that every signal
component, regardless of its pitch, duration, or intensity,
arrived at exactly the right time with the correct amplitude
and with the correct phase.
However, real world speakers do not have perfect reproduction and differ considerably from one another in transient
response. For certain pitch components, a speaker may take
a little extra time to get started while responding quickly to
others. Instead of a photo finish with all the pitch components arriving at the same time, the race is always won by
some and always lost by others regardless of program
material. The result is a time delay for some frequencies,
which results in a distortion or loss of the "edge" of those
sound qualities we associate with real life. (The technical
interpretation is somewhat more complicated because some
pitch components produce a sound that is equivalent to
breaking up into a multiplicity of late arrivals.)
Transient distortion is measured by applying a special
signal to the speaker terminals which at one moment in
SOUND
PRESSURE
It
_
--
TIM
Fig.
time has all possible pitch components of interest. At a point
one meter distant the entire sound spectrum is measured,
including all late arrivals, and we clock the total energy in
all pitch components at each moment of arrival. This is the
energy -time plot of Fig. 7.
If a speaker spreads in time the energy of what should be
an impulse, this will show in the measurement. A speaker
with internal reflection of improperly mounted or crossed over drivers will produce a staccato smear in time which will
show up as multiple energy humps for the moment when
each signal arrives. Quite often, as an example of this, you
may see a second bump a millisecond or two after the first
arrival for small cabinet -mounted speakers. This is caused by
the sound from the back of the cone penetrating into the
box, reflecting from the rigid box backwall and coming out
through the relatively transparent cone as a late partner to
the first direct sound.
To aid you in visualizing how much time smear may exist,
we will-when practicable-indicate what portions of the speaker
are involved. This is shown in Fig. 7 as the side view of
the speaker box with the front of the box at 3 milliseconds,
corresponding to the one meter distance, and the rear of the
box at the position corresponding to the time it would take
sound coming from that spot to reach the microphone.
With this measurement you can begin to sense the sonic
effect of a particular speaker's reproduction of transient
sounds. The amount of actual time smear for the high pitch
components, which give liveliness, is usually small enough
so that we can't perceive them as separate entities; all we
know is that there is something which separates the reproduced sound of many speakers apart from that live sound.
Equipment Notes
As mentioned above, these tests use several sophisticated
pieces of research equipment, and since some have no commercial counterpart, a word of explanation is in order. The
6-Impulse response.
,B
ChERG,
Probescope SS -100 spectrum analyzer has been modified to
include additional capabilities as either a tracking filter or
time delay spectrometer (TDS). As a tracking filter, it can
be phase locked to any signal from 10 Hz to 100 kHz, and
the fundamental, second, third, fourth, and fifth harmonic
automatically locked on by preset switching. The design
allows its center frequency to be phase locked to Mf ± fD
where f is the fundamental frequency of any periodic input,
M is a selectable integer from to 5, and fD is a synthesizer
offset frequency on 0.1 Hz steps to 999.9 Hz.
The time delay spectrometer modification was the subject
of three AES papers which should be referred to for details.
(See "Acoustical Measurements by Time Delay Spectrometry", J.A.E.S., Oct., 1967, Vol. 15, No. 4; and "loudspeaker
Phase Characteristics and Time Delay Distortion, Parts & 2,"
J.A.E.S., Jan. & April, 1969, Vol. 17, Nos. and 2.
The output of the SS -100 occurs at its i.f. frequency of
225 kHz, which is synchronously heterodyned to d.c. in
quadrature channels. These are time -weighted in accordance
with either a rectangular or a raised cosine multiplication,
then processed through sampled integrators. When the TDS
mode is used for test, the output of these integrators corresponds to the Fourier transform of the frequency spectrum
signal, and this is used for the energy -time plot.
For the polar energy response, the d.c. heterodyned i.f.
signals are squared and then integrated for the period of
frequency sweep. In the phase locked tracking falter test mode,
the output is a matched filter. With a one second gate, this
matched filter has a noise bandwidth of Hz and the mean
square output is logarithmically calibrated for reading the
signal suppression for the speaker test where noise is used.
1
5
4
TIME
Fig.
7-Time
6
-I»
spread of sound intensity based on Fig. 6.
1
1
dB
ENERGY
6
TIME
1
Fig.
8-Time
spread for
a
perfect speaker.
AUDIO
28
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NOVEMBER 1973
Our new receiver demodulates
or decodes any kind of 4 -channel.
Even some that haven't
been invented yet.
The Technics SA -8000X Is master of all
4 -channel systems. With special talents in
discrete. Like a built-in demodulator for CD-4
records. Pius jacks for up to three
4 -channel tape sources. And racks
fe I>
fcr future discrete 4 -channel FM.
It can handle any matrix method with ease.
Because the Acoustic Field Dimension (AFC
controls and phase shift selector adjust to the
coefficients of all the popular systems. Plus
some that haven't been tried yet. And the same
controls can help compensate for poor speaker
placement and unfortunate room acoustics.
The 4 direct -coupled amplifiers each have
22 watts of RMS power at 8c', each channel
driven. And because they can be strapped
together, you get 57 watts RMS per channel at
i
SIS,
each channel driven, in the 2 -channel mode.
That's double -power stereo.
In the FM section, we have combined a 4 -pole
MOS FET, ceramic IF filters, a
monolithic IC
and epoxy resin coils for superb reception.
FM sensitivity measures 1.91,v.
Insist on the SA -8000X for total 4 -channel.
The concept is simple. The execution
is precise. The performance is outstanding.
The name is Technics.
200 PARK AVE., NEW YORK, N.Y. 10017
FOR YOUR NEAREST AUTHORIZED
TECHNICS DEALER, CALL TOLL FREE
800 447-4700. IN ILLINOIS, 800 322-4400.
Technics
by Panasonic
Check No. 64 on Reader Service Card
»M1.1111100
.a
jiil
1111
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;.
.1411.
1.N ..10b
IIHIIIJ
Obeli
ItINNN
A second nonstandard piece of equipment is a normalizing
gain pot, which was made by ganging two precision Daven
logarithmic attenuators on the same shaft with a potentiometric switch. A clockwise rotation increases the gain in the
transmit channel and decreases the gain in the receive channel
by an exactly compensating amount. The test equipment then
sees a constant level regardless of the test level. This allows
a single setting for 100 per cent level in harmonic distortion, and the tracking filter can plot out distortion on the X -Y
recorder at any convenient rate. The full range of the normalizing pot is 32 dB with 2 dB steps and a worst case
error of±0.3 dB.
For speaker impedance testing, a General Radio 1304A
oscillator with a 908 dial drive is used as a constant voltage
source sweeping 20 Hz to 20 kHz. This is made into an effective constant current with a 5K resistor. The voltage across
the speaker is processed by the phase locked spectrum
analyzer and displayed on a Moseley X-Y recorder. If more
exact and complete impedance measurements are required,
a General Radio 1603 Z -Y bridge is used, with measurements
beyond 20 kHz normally made with a Hewlett-Packard 200
CD oscillator or a 606A signal generator.
Polar energy is tested by first mounting the test speaker on
a special motor -driven tripod with a precision sine -cosine
potentiometer mounted on the azimuth drive. The TDS output, a sweeping sine wave, is level set through HewlettPackard 350B attenuator, then through the normalizing transmit potentiometer to the power amplifier. A Tektronix 310A
oscilloscope is used to monitor the speaker drive at all times.
A Hewlett-Packard -in. condenser capsule is used for microphone pickup, and its preamplifier output fed to a HewlettPackard 450A line -driving amplifier back to the normalizing
receive pot. A Ballantine 320 true RMS meter is used as a
combined acoustic level calibrator and monitor amplifier to
drive the TDS input. The display on the TDS is, in fact, the
frequency response of the speaker and this setup is used to
check response as a function of polar angle. The frequency
response is squared, integrated, and driven to the sine -cosine
pot to be split into rectangular coordinate channels. This is
returned to the spectrometer and processed for the X -Y recording, which is now in polar format with logarithmic radius.
The frequency response setup is identical to the polar
energy setup except that several means of display are used.
First, the TDS display is photographed with linear frequency
scales for reference. Second, a Hewlett-Packard 130C X -Y
oscilloscope is set up to display logarithmic frequency coordinates. Third, a General Radio 1304A oscillator with a dial
drive is used to drive logarithmic frequency coordinates on
the X-Y recorder and the vertical is a sample and hold output obtained upon coincidence of sweeping frequency and
1304A frequency.
For harmonic distortion measurements, a Heath AG -9A
low distortion sine wave oscillator is used to drive the
speaker through level setting attenuators and a power amplifier. The Tektronix 310A 'scope is used to monitor voltage
across the speaker, while the mic is placed close enough to
the speaker to be in the near field and measure the sound
pressure in the harmonics prior to far field polar pattern
wave front deformations. To reduce capsule distortion products
due to higher SPLs, the capsule is desensitized by capacitive
loading prior to amplification.
The normalizing pot keeps the receive level constant independent of speaker power. A Ballantine 320 voltmeter is used
as a calibrated amplifier which feeds a Heath HD -1 harmonic
distortion analyzer. This is used only as a tunable notch to
reduce the fundamental component and increase the dynamic
range of the spectrum analyzer. A Hewlett-Packard 130C
oscilloscope monitors the analyzer input. The spectrum
analyzer is first phase locked to the fundamental and the
1
30
HD -1 placed in the "all -pass' position. The fundamental
component with watt drive is used to normalize the spectrum analyzer to 100 per cent. The HD -1 is then set to
"notch" and adjusted to minimize spectrum analyzer reading.
Measurement then consists of locking the spectrum analyzer
to the desired harmonic and clicking the normalizing attenuator through its 2 dB steps. The X -Y recorder is synchronously stepped with the normalizing potentiometer so
that readings can be made quickly.
For intermodulation distortion, two sine wave oscillators,
the General Radio 1304A and Heath AG -9A, are adjusted to
the proper frequencies and have their outputs added in equal
ratio and sent through precision attenuators and a power
amplifier to the speaker. Mic output is amplified, normalized,
and measured by a Hewlett-Packard 300A wave analyzer. The
higher tone, which is to be checked for intermodulation by
the lower tone, is set to 100% on the analyzer at the lowest
practical speaker drive level. It is then tuned to the appropriate sideband and manual readings taken at 2 dB power
increments. When all significant sidebands and power level
readings have been taken, the data are reduced by use of a
Hewlett-Packard Model HP-35 calculator.
The signal suppression setup is similar to that for intermodulation except that a General Radio 1390B noise generator is used with a sine wave oscillator. The normalized
microphone output is amplified and preliminary filtering
made through the Hewlett-Packard 300A wave analyzer set
to the frequency of the tone. This is done to reduce the
dynamic range requirements of the subsequent filtering. The
i.f. of the 300A (20kHz) is phase locked by the spectrum
analyzer which uses a one second gate to implement a
matched filter detector. The mean square output of the
matched filter is monitored on a meter and sent to a recorder.
At the lowest practical drive level, the matched filter is set
to 0 dB with the sine wave. The noise is then added at 20
dB higher average level than the sine wave. The normalizing
pot is stepped in 2 dB increments until either a dB drop is
noted in the matched filter or amplifier clipping occurs. The
peak speaker voltage for three sigma noise peaks is then used
dB
as the peak amplifier rating needed to produce this
suppression.
For the time -energy plot, the frequency response is taken
by the TDS. This produces one complete spectrum per
second. The frequency response is multiplied by Hamming
spectrum weighting and sent to a processor which takes the
continuous Fourier transform of this weighted spectrum. A
control unit selects the proper synthesizer digits to correspond to the appropriate time epoch for each one second
spectrum and digitally positions the horizontal axis on an X -Y
recorder to correspond to this epoch. The in -phase and
quadrature Fourier transform are squared, logarithmically
amplified, and used as the recorder Y axis drive. The control
unit steps the synthesizer and advances the recorder once per
second from starting epoch to final epoch. A maximum of
256 steps may be taken in one record.
1
1
1.
Conclusion
Our discussion has concentrated on the laboratory tests
because these are reproducible from one time to the next and
one facility to another. It is still our policy that final judgment of sound reproduction must come from a critical listening test where human values of perception are strongly
dominant. The listening test will therefore continue to be
performed as it always has. The reason we perform laboratory
tests is to make available to you impartial measurements of
how well a speaker does its job and we do this in numerical
data form for easy and valid comparison of one speaker with
another.
AUDIO
NOVEMBER 1973
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0.3% in stereo) matches the AU -9500 amplifier which delivers a massive 80 watts RMS per channel into
an 8 ohm speaker.
The TU -7500 tuner (with IHF sensitivity of 1.9 µV and THD of less than 0.5% in stereo) can be matched with
either the AU -7500 amplifier with an output of 40 watts RMS per channel into an 8 ohm speaker or the AU -6500
which provides 30 watts RMS per channel into an 8 ohm speaker. Every match looks and sounds great because
it has the unmatched engineering and design quality of Sansui.
SANSUI ELECTRONICS CORP.
Gardena, California 90247
SANSUI ELECTRIC CO., LTD., Tokyo, Japan Sansui Audio Europe S. A., Antwerp, Belgium
Check No. 53 on Reader Service Card
Woodside, New York 11377
www.americanradiohistory.com
AmericanRadioHistory.Com
Bass
Equalization
in
Loudspeakers
Dick Crawford
T'S NOT FAIR. It's just not right. I mean the way more effiIcient loudspeakers are penalized in their bass response. They
are, you know. Here, I'll show you why, and what you can
do about it.
Using the nomenclature of Harry F. Olson', we can write
the motional impedance of a loudspeaker as
(1)
Zem=
(B1)'
Zmt
motional impedance of loudspeaker in
abohms,
B=
flux density in air gap, in gausses,
length of the conductor in the voice coil,
1=
in centimeters, and
Zmt = total mechanical impedance of the mechanical system, in mechanical ohms.
Further, we can write the force exerted upon the loudspeaker
cone as
where
(2)
Zem =
f=
f=
i=
Bli
force, in dynes
current, in abamperes.
Now, suppose I had two loudspeakers, names More and
Less. They are identical except that MORE has twice the flux
where
1K12
AUDIO
OSCILLATOR
LOUDSPEAKER
+-1111.
ENCLOSURE
AUDIO
VOLTMETER
O
Fig. 1-Loudspeaker impedance test setup.
density of LESS. Perhaps the greater flux density is due to a
larger magnet. Both MORE and LESS are mounted in infinite baffles. Both speakers are driven at. equal power levels by
a good stereophonic amplifier. What do the above equations
tell us?
Obviously, the greater flux density of MORE gives it greater
efficiency. How much greater? We can answer this with the aid
of equation (2). The sound pressure generated by a loudspeaker
is proportional to the force generated by its voice coil. Sound
pressure is analogous to electrical voltage in that acoustical
power is proportional to the square of sound pressure as electrical power is proportional to the square of the voltage across
a resistor. If we double the force in (2), we quadruple the
efficiency. Thus if we double the flux density in a loudspeaker
while keeping the other factors (including the current flowing
in the voice coil) constant, then we quadruple the efficiency.
Great! But do we keep the current constant if we change the
flux density? Don't we alter the impedance characteristics
when we alter the flux density?
In most loudspeakers the impedance in the mid -range frequencies, where efficiency is specified, is dominated by the
resistance of the voice coil windings. For woofers, sometimes
the dominant impedance is the inductive reactance of the
voice coil. This means that most of the electrical power delivered to a loudspeaker gets dissipated in the resistance of the
voice coil rather than in acoustical power. This is why most
loudspeakers are less than 10 per cent efficient.
Returning to our two loudspeakers MORE and LESS, we
see that the resistance of both voice coils is identical, and thus
the speaker impedances will be very similar over most of the
frequency range. Thus the current in both speakers is nearly
identical for equal drive levels. And this means that MORE is
almost four times as efficient as LESS in the mid and high
frequency ranges.
But what about the lower frequencies? At bass resonance,
for example? Surprisingly, MORE is out of luck. Referring to
(1), we see that the resonant impedance of a loudspeaker goes
up as the square of the flux density. Thus MORE will have
four times the electrical impedance at resonance of LESS.
This means lower current, less force, less sound pressure, and
lower efficiency for MORE at bass resonance. The sound
pressure of MORE is one half that of LESS at resonance, and
the efficiency is one quarter! Foul play! No wonder low efficiency speaker systems have done so well.
AUDIO
34
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AmericanRadioHistory.Com
NOVEMBER 1973
TCD 300
The stereo cassette
deck for people who
wouldn't own anythin
but a reel-to-reel mac Inc.
The new ideas we've engineered
into the Tandberg TCD 300 may
change some of your old ideas
54 dB without the Dolby* circuits in
operation. An incredible 62 dB with
Another TCD 300 exclusive-large,
Dolby*. Frequency response of 30-
about cassette tape decks.
16,000 Hz (DIN) using CrO2 tape.
Maximum wow (WRMS) of 0.15%. It
all adds up to the kind of reliability
and clean, transparent sound you'd
expect from a fine reel-to-reel tape
machine.
meters.
These unique meters show the fully
equalized record signal at all frequencies, and accurately read the
peaks to keep you from getting audible distortion during recording. They
allow maximum utilization of the
tape, for improved signal/noise.
To begin with, the TCD 300 is the
world's first three -motor, dual -capstan cassette recorder. A hysteresis
synchronous 4 -pole capstan drive
motor assures smooth, constant
speed. The two DC EDDY spooling
motors can wind or rewind a 60 minute cassette in 40 seconds flat!
And Tandberg's exclusive servo
control gives you constant speed,
completely avoiding stress on the
tape in both wind and rewind. No
other cassette deck comes close to
handling tape this fast...or with such
great stability.
The specifications for the TCD
300, as with all Tandberg equipment, are guaranteed minimum
performance standards.
As significant as the specs themselves is the way we achieved them.
For instance, the TCD 300 uses a
minimum of high frequency pre -emphasis in recording (only 12 dB at
14 kHz with CrO2 tape). This means
significant increase in dynamic
range at the highest frequencies.
And an audible improvement in signal/noise as well.
a
The TCD 300 uses a unique closed loop tape drive system with two
pinch rollers that automatically compensate for slight differences in
cassettes. You get inaudible wow
and flutter. And you don't have to
worry about tape jamming, even with
heavily played cassettes.
Now for the specs-and what specs
they are! A signal-to-noise ratio of
Dolby
rs a
illuminated peak reading dB
The CrO2 tape switch changes re-
cord current bias and both record
and playback equalization. This
gives you full advantage of the special properties of CrO2 tape. Automatic electronic end stop, one -button
record control and built-in microphone preamplifiers add still more
control sophistication.
Ask your Tandberg dealer to demonstrate the TCD 300. You'll find it
does things the others can't. Because it has things the others don't.
other words, the TCD 300 does
not "buy" its extended frequency response and excellent signal-tonoise ratio with a reduction in dynamic range-which makes the TCD
300 fully capable of recording the
true dynamics of a live performance.
In
Trademark of Dolby Laboratories. Inc.
TANDBERG
We're our only competitor.
TANDBERG OF AMERICA INC
LABRIOLA COURT. ARMONK, N.Y. 10504
A. Allen Pringle, Ltd.. Ontario. Canada
Check No. 59 on Reader Service Card
www.americanradiohistory.com
AmericanRadioHistory.Com
jam
Well, then, why do we want efficiency? For one thing, a
more efficient loudspeaker has better damping', and thus
better transient response and a somewhat smoother frequency
response. A high efficiency loudspeaker needs a lower power
amplifier. Most component type high fidelity loudspeakers are
of the high efficiency type.
So we have a loudspeaker. What can we do if it lacks bass?
We can equalize. By equalize I mean bass boost in the amplifier. Bass boost? Does not proper equalization depend upon
a complete knowledge of the loudspeaker parameters such as
mass, compliance, flux density, et al? Or perhaps an acoustical
laboratory with an anechoic chamber, expensive microphones,
and so forth? No, I contend that an adequate job of equalization can be carried out just using an audio oscillator, a one
kil ohm resistor, an audio voltmeter, and the speaker in its
enclosure. Figure shows the test set up.
The first step is to measure the mechanical Q of the loudspeaker. Somewhere in the region from 20 to 200 Hz the
loudspeaker will give a peak reading on the voltmeter. This is
the resonant frequency, f°. We also wish to find the two frequencies either side of f° where the voltmeter reads 70% of the
value at f0. We call these two frequencies f, and f,. Finally,
1
we wish to determine the minimum impedance of the bass
loudspeaker, which is the minimum reading on the voltmeter,
and is generally a broad minimum occurring at three to ten
times f°. We call this frequency f,. What we are interested in
here is the ratio of the readings on the voltmeter at f° and f3.
Figure 2 shows the impedance plot of a 10 -inch. woofer in a
two cubic foot enclosure illustrating the frequencies and measurements sought. Such a plot can be made, if interested, by
assuming that the speaker is at its nominal impedance at 1000
Hz. By setting the oscillator to 1000 Hz and adjusting its output
amplitude until the voltmeter reads eight millivolts, then the
voltmeter reading in millivolts converts directly to ohms
impedance. Then it's a simple matter to note the voltmeter
reading as frequency is varied (not touching the oscillator
level) and then plotting the readings.
We are now ready for some simple calculations. First we
determine the loudspeaker mechanical Q from
(3)
Q=
f0
f2 -f,
Next we determine a number I call the MORE factor. It has
no particular meaning to us unless we know a great deal about
the design details of the loudspeaker.
(4) MORE factor = M.F. = V°
V,
where
V. = the voltmeter reading at f°, and
V,=the voltmeter reading at f,.
Now we come to the crux of the matter and determine the
amount of bass boost needed to equalize the loudspeaker.
(5) Bass Boost=
M.F.
0=A=e-x.W
(
1,111,19
",("ó) _(;) z
,
MSS BOOST
o
_SO.,2_11o".
11111
1
1
2-Impedance plot illustrating measurements.
Fig.
C1
.1
r15
200
eIN
1
VOLT
eOUT
RMS
1
ALL RESISTORS
GAIN
= 0 db
AT
I
2W. 10°0
1
kHz
SIGNAL CAPABILITY
1
4
=
Hz
100-
2r. R2
5
=
VOLTS
BASS BOOST = R3 + R2
Fig.
RMS
BASS BOOST r
3-Bass boost circuit.
f
°
VOLT RMS
y
I think it would be wise to explain the above equations. Tilt
procedure for determinimg the mechanical Q is not exact, but
it is a simplification of a more precise method', and is accurate
enough for loudspeakers of moderate efficiency. The greater
the Q of a loudspeaker, the less electrical power we have to
furnish it for a given acoustical output at resonance (under
steady state conditions). Alas, the greater the mechanical Q of
a loudspeaker, the more poorly damped it will be at resonance,
and the poorer the transient response. There is not a great deal
that can be done by the reader to the speaker to decrease its Q,
but we are fortunate in that a speaker with high efficiency will
give us more opportunity to electrically damp this resonance'.
At any rate the bass response is being increased by this mechanical Q, so we have to know the Q in order to calculate the
required bass boost.
But for a Q of one or greater there will be a peak in the impedance curve at resonance. The greater the flux density, the
higher the impedance peak. The higher the impedance peak,
the more bass boost required to equalize bass response. Thus
the MORE factor is a measure of the "peakiness" of the impedance characteristic.
Since the MORE factor is an indication of the bass boost
required, and the mechanical Q of the loudspeaker is a measure
of the bass boost built into the loudspeaker, we see that the
actual bass boost required is some function of the MORE factor
divided by the Q. Earlier we saw that the bass loss due to
greater efficiency was proportional to 'the square of the relative
flux density, thus we have (5) above.
We now know the amount of bass boost required, but we
don't know the frequency contour that our bass boost circuit
should follow. It the boost is less than twelve decibels at
loudspeaker resonance, the single zero, single pole circuit, such
as shown in Fig. 3, is adequate. The value of R, in Fig. 3 is
shown for the loudspeaker of Fig. 2. The bass boost starts
at
(6) fa = (f0)x(bass boost)
AUDIO
36
www.americanradiohistory.com
AmericanRadioHistory.Com
NOVEMBER 1973
The new
ADC -XT 10.
If you believe, as we do, that
the ultimate test of any speaker is
its ability to produce a true audible
analog of the electrical signal fed
to it, you'll be very impressed with
the new XT 10.
The XT 10 is a two way, three
driver, system employing a newly
developed ten inch, acoustic suspension woofer with an extremely
rigid, light weight cone and a
specially treated surround that
permit exceptionally linear
excursions.
Matching the XT 10's outstanding low frequency performance are two wide dispersion
tweeters that extend flat frequency
response to the limits of audibility
(see accompanying frequency
response curve) and significantly
improve power handling capacity.
All three drivers are mounted
in a beautifully finished, non resonant, walnut enclosure. And
in place of the conventional grille
cloth is an elegant new foam
grille.
An extraordinarily accurate
transducer, the XT 10 is characterized by very flat frequency
response, excellent high frequency
dispersion and extremely low
distortion. Finally, it is distinguished by outstanding transient
response assuring exceptional
clarity and definition.
As a result, the ADC-XT 10
rivals and in many instances, surpasses the performance of units
costing several times as much.
But why not experience for
yourself what a truly well behaved
speaker sounds like. Audition the
XT 10 at your ADC dealer now.
For more detailed information
on the ADC -XT 10 write: Audio
Dynamics Corporation, Pickett
District Road, New Milford,
Conn. 06776.
It does precisely what it's told.
5dB
F re
queftcy response: r37Hz to
3dß
10K
100
20K
Frequency response (in anechoic room).
Tone bursts at 500Hz, 1200Hz. 15,000Hz
Virtually identical waveforms trom signal generator above
and speaker below demonstrate superior transient response.
AOC
Audio Dynamics
Corporation
Check No. 9 on Reader Service Card
www.americanradiohistory.com
AmericanRadioHistory.Com
for the approximations made in the analyses is the results of
Fig. 4! In the case of other enclosure types, it is difficult to
assess the degree to which the enclosure modifies the impedance characteristics in the region near resonance. This
brings to mind an observation about enclosures. Most
enclosures not only add to the bass by additional radiation,
but they also lower the electrical impedance in the vicinity
of resonance. This latter effect leads to more current flowing
in the loudspeaker which means yet more bass. Several examples are the bass reflex, the auxiliary bass radiator (ABR
or drone cone), the labyrinth, and the folded horn. All of
these increase the amount of bass by increasing, in some
manner, the amount of acoustic radiation. This is represented as an additional resistive component in the mechanical
impedance of the loudspeaker, and thus (by equation 2) must
lower the electrical impedance. As a matter of fact, I have
designed enclosures wherein the port of the bass reflex was
designed primarily to control the speaker impedance characteristics'. I suspect that some of the aperiodic speaker enclosures on the market now are designed with this same goal.
There you have it. A wrong recognized; a cure proposed;
proof that it works. Do I guarantee happiness? No, but if
your loudspeaker fits the prescription described above, then
you might try bass equalization. I can guarantee more bass!
Theoretically, it is possible to equalize the response of a
loudspeaker in the frequency range below its resonance, but
I have never had much success in so doing. The slope of the
equalization curve below speaker resonance is very steep, and
the amount of equalization required very large. The practical
problems seem greater than the rewards.
Figure 4 shows the results. The bass boost starts at about 105
Hz, is up about eight decibels at 50 Hz, and reaches a peak of
10 decibels at about 30 Hz. Of course, this represents the transmission thru the entire amplifier and not just the bass boost
circuit.
The before and after effects of the frequency response for
the loudspeaker speak for themselves. The measurements
were taken with a Hewlett-Packard loudness analyzer in my
den. Notice that the bass response has been extended for one
octave. The falling off in the 400 Hz region is due to the
crossover network for this speaker. The response is smooth and
lacks large peaks.
Where, say you, is the catch? Yes, there is one. This technique, that is, the equations as given, is valid only for
speakers in sealed enclosures. In fact, the only justification
References
1.
Olson, Harry F., Acoustical Engineering, D. Van Nostrand Company. pp.
2.
Briggs, G.A., Sound Reproduction, Wharfedale Wireless Works, 1953, pp.
3.
Jordan, EJ., "Loudspeaker Enclosures," Wireless World, January, 1971,
124-133.
110.122.
pp. 2-6.
Briggs, G.A., op. cit.
Crawford, Dick, "Another Look at Parallel -Connected Speakers," Audio,
November, 1970, pp. 24, 26.
4.
5.
Directory Addenda
SPEEDS (see
A-33, 45, 78
B-33, 45
C-33 only
TURNTABLES
r
AUTO TURNTABLES
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MANUFACTURER
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SONY
PS
9
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2251
AC
2251
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0.04
58
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12
AC
Integ
12
3
Servo
r
lb
Dir.
5 oz
6'4
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5 oz.
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164
18
lb.
11
oz.
4''
SPECIAL FEATURES
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ball
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159.50
Auto lead-in: auto ret., repeat.
134 9
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ball
bal.
417
0
349.50
Speed tuning
191/2
bid.
r71/2
w/built-in
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7P/4
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33, 45, 78
33, 45
F-cont. variable
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200
MM -327
Card.
Elect.
Alum.
Brshd.
gold
low
30-16k
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20
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Omni
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AUDIO
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On -oft swit
NOVEMBER 1973
What makes Evolution One sound so good
are all the speakers which
are supposed to
sound so much better.
Our design engineer.
Just how good is it?
Great design only comes from
great designers.
You'll be surprised. Especially
when you pit it against speakers
three and four times higher
in price.
It has an extraordinary wide
range. Low distortion at all
frequencies. Wide dispersion.
And uniform flat response.
Which is why our Director of
Loudspeaker Design and
Research, Charles L. McShane,
is an important factor in the
development of this new speaker.
He has spent over twenty years
design of
loudspeakers. With the top
manufacturers in the industry.
His design credits include some
of the best selling acoustic suspension speakers now on the
market (several are considered
standards of the industry).
in research and
Some honest talk about
a new speaker and its non revolutionary advances.
the world ready for a non revolutionary speaker?
15
We think the serious listener
might be. Behind the development of Evolution One is the
same philosophy that has made
Sherwooc
receivers.
a
leading name in
We've deliberately not sought the
sensational breakthroughs.
We put the emphasis on refining
technology which currently
exists. Reining, perfecting,
evolving the state of the art.
Equally important, he believes,
as Sherwood always has, in
design simplicity.
No tricks. No gimmicks.
You will find Evolution One is the
essence of simplicity.
A two-way loudspeaker system
utilizing a 10 -inch woofer and a
1.3 -inch tweeter. It is an acoustic
suspension design.
While the design is fundamentally
simple, the execution involves a
variety of techniques which
cumulatively produce a
remarkable sound.
In fact, its low frequency output
and distortion are better than any
speaker system we know of for
home use.
The one revolutionary feature.
We have priced the Evolution
One speaker at under $100.
When you hear how it sounds,
you'll know why we think that it
offers the outstanding
performance -per -dollar we're
famous for.
Write us for complete information, and the list of selected
Evolution One loudspeaker
dealers.
Sherwood Electronic Laboratories
Loudspeaker Division
4300 N. California
Chicago, Illinois 60618
aIOILIdOt'1
one
Another best buy from Sherwood
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íi
Price Corrections
On page -80 of the speaker section in the September DiOn page 48 in the manual turntable section, the Thorens
rectory, the Hartley Concert Master and Holton series TD-215AB and TD-I25B turntables had their prices ex speakers were listed at price per pair. The prices are for changed.
single units.
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AMPS
dr-
MANUFACTURER
OLSON
Pr
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!
ï//////////
1CS
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AM 395
12
0.75
0.4
AM 372
8
1.75
1.5
2028k
0.52
1.5
2.0
58
40
2.8
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4-16
1112
20
1.8
z
2.0
55
45
3.0
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4-16
TA -1055
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10-40k
VC
69.99
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111
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151/2 z
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249.50
39.98
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10-60k
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SPECFEATURES
'T
41
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20 + 20 W. at 40-20k; wood
cab.; 2 tape mon.; dir. spkr.
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TA-
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2.0
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+
30 W. at 20-20k; 2
tape mon.;
e 53/41
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TA -1130
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50 W. at
2
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51/4
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(B) TA -3130F
70
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7-30k
10-200k
(B) TA 3200F
110
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5-35k
1.0
71 z
200
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5-200k
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249.50
171/4
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z 57/x
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PRE -AMPS
MANUFACTURER
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13
79.95
Flat sound panel; polyplanac
8 -way design.
40
230.00
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patterns
brn
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Vinyl
Cloth
brn.
20
150.00
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wal.
Wal. or
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AUDIO
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NOVEMBER 1973
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329.50
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dir. spkr. coupling.
614
+ 35 W. at 20-20k; wood cab.:
dir. spkr. coupling; 2 tape mon.
x
141/4
334 399.50
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331 499.50
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224
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1814
15 W. at
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dit. spkr. coupling.
20
5%
1814
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249.50
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10
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259.98
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10
16
189.98
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10
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214.98
Joystick bal.
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AUDIO
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built-in
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AMPLIFIER
MANUFACTURER
Records.
89.98
16'7
x
NOVEMBER 1973
is only the beginning
of the Realistic STA -150 story.
Auto-MagicTM
401.0111.
But what a beginning! Touch the tuning knob and Auto -Magic
deactivates the AFC for easy FM station selection. Reliease
the knob and Auto -Magic fine-tunes the station and locks
it in. But it isn't Auto -Magic alone that makes this a greet receiver.
Complete STA -150
Stereo System
There's dual gate FET FM, along with 7 integrated circuits
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And tape copying facilities, too.
Then there are those "little things" that make Realistic receivers
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The happy ending is the price:
34995
SPECIFICATIONS. FM TUNER. Sensitivity: 1.6 µV IHF. Stereo Separation:
kHz. Signal -to-Noise Ratio: 70 dB. Selectivity: 56 d'B.
45 dB at
AM TUNER. Sensitivity: 20 µV (at terminals for 20 dB S+'.N/N).
Selectivity: 30 dB. AMPLIFIER. Power: 160 watts ±1dB at 4
ohms, 100 watts IHF at 8 ohms, 65 watts RMS at 8 ohms. Frequency
Response: 20-20,000 Hz. Power Bandwidth: 15-70,000 Hz.
1
Harmonic Distortion: less than 1% at rated output.
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Apt #
Name
Street
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291
State
ZIP
LAB -36A with Base
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Reg. 79.95.
Two Optimus-1
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8
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CASSETTE TAPE RECOROING BIAS
Martin Clifford
a signal voltage (Fig. 2) is applied, its
effect is to increase and decrease the
amount of bias, producing an equivalent
IN TUBE and transistor circuits, the
word bias means a voltage, generally d.c., applied to some element
of an active component to produce a
linear output. There are exceptions, of
course, most notably in the case of
class -C amplifiers functioning as frequency multipliers. However, for audio
applications, the role of bias is to help
ensure undistorted output from tubes
or transistors.
For a component such as a tube, for
example, bias in the form of a negative
voltage determines the quiescent or
operating point Q, as shown in Fig. I.
The graph or transfer characteristic is a
plot of grid voltage vs. plate current.
This first drawing shows that a bias of
-2.5 volts results in a plate current of
slightly more than 4 milliamperes. When
variation of plate current. Because the
swing is between points A and B, the
linear portion of the tube's plate current
-grid voltage characteristic, the variation in plate current (the output) is also
linear. However, if the bias is incorrect,
either too large or too small, the output
waveform is distorted. Fig. 3a shows
the effect of insufficient negative bias;
Fig. 3b excessive bias.
This isn't as far removed from bias
for magnetic tape as you might think,
for one of the functions of tape recorder
bias is to help produce linear output.
But there the similarity ends, for tubes
and transistors are amplifying devices;
magnetic tape is not. Magnetic tape,
sou,
,.,,
a.,
Fig. 1 -Grid voltage vs. plate
current curve. The d.c. bias voltthe operating
age determines
point, Q.
2
rar
Fig. 2 -Because of the presence of
d.c. bias, operation is along the
linear portion of the characteristic
curve.
9
6
r ©6
I
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4
CHARACTERISTIC,
Plate current
CURVE
output
bI
3
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CHARACTERISTIC.
CURVE
Plate curie
output
--
Negativem-p
-
Grid Vo tage
I.=- -r-
'Positive
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Posdive
Grid voltage
3
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7
7
voltage
9
direction
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3 -Distortion
73
13
4íC13
positive
tive.
6
t
2
Fig.
2
9+I
--Input
voltage
occurs when bias is moved in an excessively
and also when it is made excessively nega -
(a)
44
though, possesses an ability that tubes
and transistors do not have -the ability
to retain the signal, pending amplification. However, whether this retention
is linear or nonlinear depends on the
way the tape is biased during recording.
It may seem strange that magnetic tape
can be biased in a manner reminiscent
of tubes and transistors, but not when
you consider the way in which tapes
are magnetized and demagnetized.
Hysteresis Loops
The magnetic behavior of substances
can be graphed, just as it is possible
to plot the characteristics of tubes and
transistors. The number of available
magnetic flux lines or flux density per
unit area (represented by the letter B)
depends on the permeability of the
material. Various substances have different amounts of reluctance to the
presence of magnetic lines, much as
they also have differing amounts of
resistance to the passage of an electric
current. A simple example would be a
horseshoe magnet with a given magnetic strength, H. The number of
magnetic lines of force existing between
the adjacent north and south poles of
this magnet would depend on the
material placed between the poles. For
iron there would be more lines of flux;
for air, fewer.
A permanent magnet represents a
condition in which the magnetizing
force, H, is relatively constant. The
magnetizing force, however, could be
variable, as in the case of an electromagnet, produced by a varying alternating current flowing through a coil. A
ferrous substance surrounded by the
magnetic field around the coil would
become magnetized, first in one direction, and then in the other. The poles
of the ferrous substance, possibly a
small iron bar, would keep reversing,
in step with the frequency of the magnetizing current flowing through the
coil. Further, the resulting magnet would
also vary in strength, possibly ranging
from weak to strong.
Figure 4 is a graph of the behavior
of the ferrous material. At first nothing
happens when the magnetizing force, H,
is increased from 0 to I, moving to the
right along the horizontal axis representing the magnetizing force. This "non action" can be considered in the same
way as applying a force to a stalled
heavy object, such as an automobile,
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NOVEMBER 1973
We challenge any other manufacturer
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AmericanRadioHistory.Com
The Innovators
in an effort to get it moving. There
will be no action until the applied force
can overcome the inertia of the car. In
the same way, the magnetizing force
H must overcome the inertia of groups
of iron atoms to magnetization. Once
the magnetization process starts, though,
the flux density, B, of the substance
rises rapidly. Note the distance along
the H axis from 1 to 2 is about the same
l
-B
Fig. 4-Graph of the magnetizing
and demagnetizing behavior of a
ferrous material.
Fig.
(left).
5-Conventional
hysteresis
1-that is, each of these
distances represents an equivalent
amount of magnetizing force. From 0 to
I nothing happens, yet from
to 2 the
value of B rises rapidly.
As H is increased, B increases, but
not indefinitely. At point C on the
graph, any further increases in H will
produce only a small increment in B,
and so we call this the saturation point.
If the graph were to continue beyond
point C, it would start to assume a
slope parallel to the H axis.
If the magnetizing force is now decreased, the level of the flux density of
the material that was magnetized will
also decrease but some magnetic flux
will remain, even if the magnetizing
force H is removed. At point D on the
graph, for example, the value of H is
zero, but the substance is still partially
magnetized. We can, of course, return
the material to its original, unmagnetized condition, but only by applying
a magnetizing force in the opposite
direction. The point at which the graph
crosses the -H axis (-1) indicates complete demagnetization, but note that we
are now on the -H part of the horizontal
axis. If the magnetization is continued,
as from 0 to
1
loop (right); more desirable curve
the substance will become more and
more magnetized; but the limit will be
reached at point A. Here the application of the magnetizing force will not
result in much of an increase in the
flux lines around the object being magnetized. Again, this is a saturation point.
At point A we can gradually reduce
the amount of magnetizing force until
it reaches zero. At this juncture, the
graph crosses the vertical axis at point
E. If we were to stop here, the magnetizing force would once again be
zero, but the substance being worked on
would still be a magnet-that is, it
would be surrounded by its own magnetic lines of flux. This is comparable
to the situation that prevailed at point
D on the graph, but with one difference.
The poles of the substance being magnetized have been transposed.
If we now apply a magnetizing force
of +H, similar to that used originally,
we will reach point on the graph. The
resulting graph looks somewhat like a
loop and is called a hysteresis loop. The
shape of the loop depends on the kind
of material being magnetized.
1
Shape of the Hysteresis Loop
The hysteresis loop of Fig. 4 is a
basic diagram used by engineers to
indicate magnetic properties. In general,
the closer the loop approximates a
square-that is, the greater the area
enclosed by the curve-the better this
characteristic will be for recording
purposes (Fig. 5). The vertical axis of
the graph represents retentivity, while
the horizontal axis is coercivity. Retentivity accounts for higher output and
better low -frequency response; coercivity is responsible for extended high
frequencies. Coercive force is the force
required to reduce magnetism to zero;
it can be regarded as a magnetizing
force applied in a negative direction.
Retentivity is the magnetic flux that
remains in tape after saturation with
the magnetizing force returned to zero.
a
Saturation Curve
Fig.
6-Saturation or transcon-
duction curve.
Fig. 7-Saturation curve without
the hysteresis loop from which it
was derived. A -B and A' -B' are
linear portions.
46
When a substance is subjected to a
magnetizing force, there is at first a
slow increase in the amount of magnetization, followed by a linear rise in
which the amount of magnetization is
proportional to the magnetizing force.
The remainder of the curve becomes
nonlinear as magnetic saturation is
approached. Known as a normal
saturation or transconduction curve
(as indicated in Fig. 6), it is derived
from the graph of the hysteresis loop.
The normal saturation curve can be
drawn without its accompanying hysteresis loop, as in Fig. 7. The lines between
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NOVEMBER 1973
The most precise tonearm has been added
to the most sophisticated electronic turntable
ever produced.
When the now legendary Thorens
TD -125 electronic transcription turntable first revolutionized the high fidelity
world, Stereo Review acclaimed it as
"unquestionably one of the elite among
record players. It would be hard to
imagine a unit that performs better."
Impossible as it may seem, we've
eclipsed ourselves with the Thorens
TD-125AB Mark II.
To start, its completely new, nine
inch straight tubular TP -16 gimbal
suspension tonearm is mounted on
polished ball bearings. The result is rock
steady balance regardless of the gyrations in the groove. Then there's
frictionless anti -skating control. No
springs. No weights. Designed for ultra
low tracking, you can use any
quality high compliance cartridge in the plug-in shell.
Tracking error is less than
0.2°.
Other features include: precision,
2 -way damped, front panel cueing
control; 7 lb., 12 -inch dynamically
balanced non-ferrous die cast platter;
tonearm and drive system isolated for
shock -free operation; new resonant-free
rubber turntable mat; 161, 331/2, 45
rpm speeds; walnut base.
Visit your Thorens dealer for a
TD-125AB Mark II demonstration.
You'll see for yourself why High Fidelity
said: " ... This beautiful instrument
provides a mark for others to aim at."
Elpa Marketing Industries, Inc.,
New Hyde Park, N.Y. 11040 / 7301 E.
Evans Rd., Scottsdale, Ariz. 85260 /
Canada: Tri -Tel Assocs.
THOR5®EN
TD -125ÁB MARK II
Motor rotor speed
must be precise. That's
why the TD-125AB Mark
II uses a solid state electronic motor drive system. A solid state Wien
bridge oscillator governs
the rotor speed of the instant starting, high torque, belt -driven
16-pole synchronous motor. Rumble is
reduced to inaudibility. You can make instant
speed adjustments (± 2%) and monitor
them on the built-in illuminated stroboscope.
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points A and B and A' and B' are the
linear portions of the curve. Note the
similarity between this curve and the
transfer characteristic shown earlier in
Fig. 1. We can now use this curve to
show the effect of recording a signal on
tape.
In Fig. 8 the normal saturation curve
is shown above and below the H axis.
If magnetization in the reverse direction
has the same force as forward magnetization, the lower half of the curve will
be a mirror image of the upper half.
Note, in Fig. 8, there is no bias and
the only input is that of the signal
itself. While the input is a sine wave,
the output is a distorted waveform since
just the nonlinear portion of the graph
is being used. To overcome this condition, bias can be applied to put the
operating point on the linear portion
of the curve. The curve, however, has
two linear sections, one above the H
axis and the other below it. The bias
could be d.c. and with one polarity
would utilize the lower portion of the
curve or with the opposite polarity,
the upper linear portion. In early tape
recorders that is what was done. This
kind of biasing technique, however,
AUDIO SIGNAL
A
1
nr
SINE WAVE BIAS
V
00uit1iamiT4ua1
Fig. 8-Saturation curve
applied signal without bias.
and
Fig.
9-A.c.
bias plus signal is
Mixed Signal
(bias + audio)
AC bias
Audio
Signal to
be recorded
Fig. 10-Effect of a.c. bias is to put signal on linear portions of saturation
curve.
48
In broadcasting, the process of loading an audio signal on a sine wave
carrier of much higher frequency is
called modulation. However, in tape
recorders, the audio signal does not
modulate the bias but mixes with it.
Figure 9A shows an audio signal while
9B in the same drawing represents sine
wave bias. With mixing the amplitude
of the bias remains constant, while in
modulation the instantaneous values
of the carrier keep changing. However,
with either mixing or modulation, if
we join the peaks by an imaginary line
we will have a graph of the audio
signal. Since there are two peaks-a
Biasing Tape
a
mixing process, not modulation.
Output
signal
Mixing vs Modulation
positive and a negative peak for each
cycle of bias-the result produces the
effect of a duplication of the audio
signal.
MIXING
MODULATIO',
D
takes advantage of only one small
section of the saturation curve, and as
a result, d.c. biased tape recorders had
a restricted dynamic range. The modem
technique is to use .sinusoidal a.c. for
bias.
Using sine wave bias instead of d.c.
now presents us with a technique for
working with both linear portions of
the transconduction curve. Figure 10
shows the complete action. Here we
have the hysteresis loop and its resultant magnetization curve. The audio
signal is mixed with an a.c. bias current
and it is this mixture that is applied to
the tape during recording. Note that
the mixed signal has an upper and
lower audio component and that each
of these components is a replica of
the original audio signal. Our magnetization curve, because of the presence
of the a.c. bias, now has two operating
points, both of which are centered on
the two linear portions of the characteristic. This depends on the amount
of bias current which must be such that
the audio signal portion of the mixed
signal is applied to both linear portions of the magnetization curve.
Essentially, there are two outputs-one
for the lower part of the curve and one
for the upper portion. Both combine to
supply a single output signal.
Now what about the nonlinear
section of the magnetization curve? The
bias is being applied to both portions
-that above the H axis and that below
it. This means there will also be nonlinear outputs. However, these cancel
since they are out of phase. The technique is the same as that used to get
harmonic cancellation in the output
of a pushpull amplifier.
AUDIO
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NOVEMBER 1973
NewAvid Series 100
High Fidelity Speaker Systems.
From left to right: Model 100, Model 102, Model 103
o
An exciting new experience in accurate sound and
imaginative styling...
Avid Series 100 Speaker
Systems.
Avid speakers are the
premium quality products of extensive research
frcrn a company that has
pioneered in quality audio
components for over 20 years.
A -B any of the Series 100
models, with their unique
'user -changeable decorator
/ grilles, now at better audio
shops near you. From
$79.50 to $139.50.
CORPORATION
etr
Tripps Lane, East Providence,
R.I. 02914 Tel. (401) 438-5400.
10
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The a.c. bias, for linear output, must
not only be a pure sine wave, but must
be evenly distributed around its X
axis. This means there must be no d.c.
component present in the bias since
this would have the effect of pushing
the operating point up or down on the
magnetization curve, depending on the
d.c. polarity.
Linearity of output is also dependent
on the lengths of the straight line
portions of the magnetization curve,
and these, in turn, depend on the way
the cassette tape is manufactured. If
the straight line portions are small
relative to the amplitude of the recording signal, the result will be use
of the nonlinear sections of the curve,
producing distorted output. If, however,
the input audio signal is deliberately
restricted to avoid this possibility, then
the linear portion may be underutilized,
resulting in limited dynamic range.
More About Bias
Bias, then, is a constant high -frequency
signal that is mixed with the signal to
be recorded. Its prime function is to
permit recording a signal on magnetic
tape in such a way that the output is
distortionless, while at the same time
supplying a good dynamic range. But
this is by no means the whole story.
The bias frequency is in the supersonic range and is usually somewhere
between 30 kHz and 100 kHz, or
possibly a bit higher. As a general rule
of thumb, cassette recorder manufacturers establish the bias frequency
at about five times (or more) than the
highest recorded audio frequency to
avoid beats between harmonics of the
audio signal and the bias.
Frequency response is affected by
bias. This means that on fixed bias
cassette decks, control of this important
factor is out of the hands of the user.
Bias is set at the factory by the recorder manufacturers. An examination
of existing cassette machines shows
there is roughly a 30% plus and minus
variation among all cassette recorders
in bias level settings for what can be
considered "normal" or "zero" bias.
These variations in bias, as mentioned
earlier, affect a tape's frequency response characteristics.
The ability of a tape to perform
properly over a wide range of bias
settings is called bias tolerance or bias
range. This is one of the factors to
look for when buying cassette tapes.
Bias range should be as broad as
possible. The wider the bias tolerance,
the more likely the cassette will perform well in all cassette players, with
or without a bias selector switch.
BIAS CURRENT. PERCENT
o°o
5%
10%
15%
50'0
1
Regular. Normal or
NONE
Standard
I
I
3-POSITION
I
I
Regular, Normal or
Standard
2 -POSITION
CrO,
I
Regular. Normal or
Standard
Low -Noise or
Extended -Range
rut
Typi cal
bias
current
range
of
various
cassette
tapes
Fig.
11-Bias current ranges of various cassettes.
50
Bias noise is the major contributor
to overall tape noise and hiss. It is
present on all tapes, even when no
signal is present. Obviously, it should
be as low as possible; the ideal is
zero.
Some
cassette equipment manufacturers calibrate their bias oscillator
output with a specific tape in mind. In
all tape systems, the noise level (hiss) is
also a function of the recorder itself.
If low-level signals are recorded at
higher levels and then played back at
much lower levels, there will be a
considerable reduction in hiss. If the
equipment has Dolby noise reduction
circuitry, the noise level can be diminished even more.
Tapes and Bias Current
The amount of bias current (Fig.
II) required by a cassette tape depends
on the manufacturing processes used in
making the tape. Inexpensive recorders
do not have a bias switch and so the
user has no way of varying the bias
current.. Bias in such recorders is sometimes referred to as "normal" or "standard" or "regular." On a scale of 0
to 100, fixed bias recorders operate
with a bias current of 5 percent or
less. However, the fact that a recorder
uses fixed bias does not mean that all
"regular" tapes made by all cassette
manufacturers will produce the same
results. Correct bias will produce linear
output, but only if the properly formulated cassette tape is used with it.
As an example, TDK's Super Dynamic
and Extra Dynamic tapes can be put
in fixed bias recorders, but they are
also designed to work well with bias
currents as high as 10-15 per cent.
Recorders with no bias switch can also
use TDK's LN or F -series cassettes.
A more flexible type of cassette recorder is one that has a two -position
bias switch. One position is for ferric
oxide (FeO) tapes and is generally
marked standard, normal, or regular.
With the switch in this position, the
recorder works in the same way as recorders that do not have a bias switch.
With cassette decks that have a two position bias switch, the second position is generally marked CrOZ, the
chemical symbol for chromium dioxide.
These tapes, as the name indicates, use
particles of chromium dioxide instead
of ferric oxide, as the magnetic particles on tape. While chromium dioxide
tapes do represent a forward step to
high fidelity since they give a better
high -frequency response (or as good as
ED), the tape as originally manufactured was excessively abrasive and
(Continued on page 105)
AUDIO
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NOVEMBER 1973
`EmpiYMpealtels
1oogiat('souíd great.
c.Asanyoie whip's tried them.
`From the Grtics...
"What a speaker! ...The sonic presentation was excellent: ':oiees were latural with no
coloration: orchestral music was balanced ir.d full: trarsi, nts came thr uga 2!t ar ly:
the organ sounded authentic. Indeed, for a system of its si'.e and price design(:1 for
High fidelity
home use, the Grenadier strikes us as among the hest:'
"\lost impressive range and power...bass
is clear and very deep.
Distortion was quite law even at high sound levels
Audio Magazine
"Superior transient response...extreme e a-ity, will not
break up under any normal or even super normal pu, ling...
Larry "tide, American Record Guide
`From theGPublíc...
"The rich true sound of stereo R. A., Portsmouth, N.B.
"The stele for my wife ...the sound for me:' W. S., CaJwga
Park, Calif. "Superior sound over anitii-ig
near it in price:' J. A., Hyattsville, Md. "That's
good sound 1). 0., Vallejo, Calif. "1 love
it: you made -t:' R. G., New York, N.Y.
"This speaker is truly a work of art!
J. F., Vancouver, B. C. "Full sound
even at low levels:' W. G., Alexandria,
Va. "Can handle large amounts of
pow er:D. M.. Huntsville, Ala.
"Fantastic bassi' A. II.. Burke.
Va. "tio ugly grill cloth:
B. M., Newark, N.J.
Incredible fidelity:'
K. K., Dallas, Texas.
IFE
Write for von7free Empire Guide to Sound. t)csign.
Empire Sci ntificCarp.1055 stc-zz.1rt
(
otricrt (rt.'
.
r>'
115
;',1
ANEW
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Advent Loudspeaker
Archer Tape Solder
from Radio Shack
No soldering iron is necessary-just
twist your wires together, wrap with
Tape Solder and melt it with a match,
candle or lighter. Said to be ideal for
on -the -spot wiring and repairs, Tape
Solder comes in a resealable plastic
pouch of 100 pre-cut pieces for 89e.
Technics Turntable
The Advent/2 is housed in a high
density polyurethane inner shell which
is bonded to a white molded thermoplastic outer shell with a silver-gray
grille. Said to allow the manufacturer to
invest more cost in internal components,
this cabinet is lighter and less expensive
to produce than a wooden cabinet
of equivalent acoustical performance.
The system employs an acoustic suspension woofer (with a magnetic structure as massive as the original Advent
loudspeaker) and two direct radiator
tweeters, claimed to provide maximum
dispersion with no interference effects.
Resonance is 58 Hz; crossover, 1500
Hz; impedance, 8 ohms; recommended
minimum power, 10 W./channel
Measuring 11' in. x 19 in. x 71/2 in.
deep, the Advent/2 is available at
$ 58.00.
New TDK Booklet
The TDK Guide to Better Recordings
is a collection of tips and suggestions
on how to make high quality recordings
on any cassette deck. Step-by-step
pointers show the recordist how to begin and follow through to the finished
tape. Also covered are recording levels,
reading VU meters, avoiding hiss and
distortion, bias settings and noise reduction systems. Free from your local
TDK dealer.
Panasonic is now producing a line of
high quality, high fidelity componentsthe Technics line. Among these is the
SL -1200 direct drive turntable. The
turntable has, in effect, one moving
part: the outer rotor of the motor and
its shaft, of which the platter is an
extension. Lacking idlers, belts and
gears, the unit is said to rotate at the
exact speed required without vibration,
wow or flutter. The platter is aluminum
diecast, dynamically balanced, weighing
3.86 lbs. with a 13 -in. diameter. Speeds
are 33'/3 and 45 rpm; wow/flutter, less
than 0.03% W. r.m.s.; rumble, better
than -70 dB (DIN B); effective tonearm
length, 821/32 in.; overhang, '/, in.; minimum tracking force, 0.4 gm. There is
also a pitch control with a 5% electrical adjustment, separate for each
speed. Price: $269.95.
41.J.
`ir
I
'
iFe`/U
z
r
f,0
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t
Radiometer Distortion
Analyzer
the input signal to the amplifier to the
desired level. Using only milliwatts of
power from your amplifier and reacting
much faster than a common fuse, this
component is available for $35.00.
Ferrograph Recorder
Said to be a complete audio performance test set, the BKF 10 incorporates
a distortion meter, sweepable AF oscillator, amplitude response meter, and a
frequency indicator, all of which operate automatically. The unit determines
both distortion factor and frequency
response while the input signal is
swept through four frequency decades
from 20-20kHz. Results are continuously
displayed on the front panel meters.
The distortion meter can be converted
to a S/N meter by means of a pushbutton and noise levels are displayed
from -80dB to -20dB.
Nortronics Recorder Care Kits
The four new QM series kits are composed of all the essential items for inspection and cleaning of all types of
recorders. Model QM -6, for cassette
recorders and players, is $9.90. QM-7
is for 8 -track cartridge machines, $9.90.
QM -8 is designed for reel-to-reel recorders, $9.90. Model AM -9 is especially designed for cleaning all magnetic heads and is priced at $3.35. All
kits are complete with detailed instructions for use.
Hartley Speaker Sentry
This self-powered, solid state control
utilizes a closed loop feedback circuit
to limit the amount of power dissipated in a speaker. Should the power
exceed the level you have preset on
the control, from
to 100 W. rms, the
Speaker Sentry automatically reduces
1
The
Super-Seven is a 3 -speed,
reel unit offering several
options. The recorder is available in
2- and 4-track stereo models with or
without an integrated power amp and
101/2 -in.
speakers. With 3 speeds (7'/, 33/4,
17/8 ips), the Super -Seven is the only
reel-to-reel machine offering l'/a ips
with Dolby B noise reduction. An
optional high speed unit operates at
15, 71/2 and 33/4 ips (Dolby not available
for 15 ips) at no extra charge. Solid
state with an FET front end, this unit
features instant slur-free starts on
record and PB, bias adjustment on
front deck, variable speed wind/rewind,
pushbutton tape/source comparison
for each channel, electronic editing,
pushbutton bias readings and tape
track transfer, mic-line signal mixing,
and automatic head demagnetization.
Prices: 3 -speed deck in walnut case
(2 or 4 track), $950; 3 -speed deck (2
or 4 track), with amp and speakers,
$1000; Dolby unit, $125.
www.americanradiohistory.com
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Equalization in the Home
John Eargle*
significant advances in home music listening in the last five years have been the advent of
quadraphonic sound, the general adoption of B -type
Dolby noise reduction, and the "normalization" of loudspeaker/room response through system equalization. While
quadraphonics represents a distinct revolution in the listening
experience, noise reduction and system equalization are
evolutionary, providing only improvements in what we may
call the "transfer function" from studio to listener.
Our increased concern with these improvements stems
mainly from the revolution which has been going on in the
area of musical values; today, about 90 per cent of recorded
product in this country is rock/pop, and virtually all of this
product has its genesis over loudspeakers in the control room.
Thus, noise reduction and equalization can justifiably be
sought as ends in their own right.
Quadraphonic sound is happening at every turn, and the
15 -year -old mono -stereo controversy is being re-enacted all
over again. Noise reduction is being introduced gradually,
and in a comparatively orderly fashion. It has long been an
important part of the original recording process. A while ago
it found its way to the cassette medium-one which was
sorely in need of it. It has recently found its way into the
production of reel-to-reel tapes, and it can make this medium,
in either a stereo or quadraphonic configuration, the superlative one it was meant to be. It has also been introduced
into FM broadcasting, and there it promises greater effective
coverage for classical music stations.
The evolution of home sound system equalization has been
neither orderly nor clear-cut in its direction. First of all,
it has been, and will likely continue to remain, a fairly exTHE MOST
*Altec-Lansing
A
pensive "embellishment" on what is already a good sound
system. Many systems, in many good listening rooms, simply
do not need specific contouring of the system to the room.
On the other hand, a marginal low -powered system cannot
be equalized effectively at all.
A problem which has plagued the general adoption of
home equalization has been one of adequate instrumentationeand who is to man that instrumentation. Sound level
meters are rare; '/3 -octave noise tapes are rarer-and Real Time Spectrum Analyzers are not only rare, but expensive
as well. It seems that the average audiophile is expected to
equalize his own system by ear, since the number of dealers
willing to provide the service is suprisingly low.
Let us now consider in detail the particular goals of equalization, some of the specific hardware available for the purpose, and instrumentation necessary to equalize accurately.
The Goal Of Sound System Equalization
Most professionals consider sound system equalization to
be the answer for the audiophile who wants to duplicate in
his listening room the acoustics and ambience of the recording studio control room. This is an ambitious goal, and
it can, quite honestly, be met only through the use of detailed '/3 -octave equalization. Before this can be done, care
must have been taken that the power-handling capabilities
of the speakers and amplifier at hand are equal to the demand; both the watts and the ability to handle the watts must
be duly assessed. It's quite an investment-but one well worth
it for the dedicated audiophile.
A second function of equalizers is met by the myriad one octave devices which are available. These operate in a sense
as "super" tone controls-such devices have perhaps nine to
a
0
100 Hz
Hx
ESCPUENCE IN CYCLES PER SECOND
Fig. 1-The Altec Acousta-Voicette one-third octave room Fig. 2-The SAE MARK VII Stereo Equalizer and its family
response equalizer and two typical electrical equalization of curves.
curves produced by it.
AUDIO
54
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NOVEMBER 1973
Some of the reasons why
other turntables don't perform
quite like a Dual.
Because of the wide acceptance and acclaim
Dual has earned over the years, especially among
audio experts, many Dual features inevitably appear on
competitive turntables.
To copy a Dual feature is one thing: to achieve
Dual performance and reliability is quite another
matter. The true measure of a turntable's quality is
not its features alone, but how well the entire unit is
designed and manufactured.
Following are just some of the ways in which
Duals differ from other automatic turntables.
Gyroscopic gimbal suspension.
The gyroscope is the best known scientific
means for supporting a precision instrument that
must remain perfectly balanced in all planes of
motion. That is why the tonearms of the 1218 and 1229
are suspended in true, twin -ring gimbals.
Every Dual gimbal is hand-assembled and
individually checked with gauges especially developed
by Dual for this purpose. This assures that the horizontal
bearing friction of the 1229 for example, will be no
greater than 0.015 gram, and vertical friction no
greater than 0.007.
,
True single -play automatic tonearm.
A turntable of the 1229's caliber is used primarily
in its single play mode, so the tonearm is designed to
parallel a single record on the platter. For multiple play, the entire tonearm base is moved up to parallel
the tonearm to the center of the stack.
The 1218 tonearm provides the single -play
adjustment within the cartridge housing, and the
cartridge pivots around the stylus tip to maintain
the correct overhang.
Stylus pressure around pivot.
Today's finest cartridges, designed to track
at around one gram, have little margin for error.
In the 1229, therefore, the tracking pressure scale is
calibrated within 0.10 gram from 0 to 1.5 grams.
To maintain perfect balance on every Dual
tonearm, stylus pressure is applied internally and
around the pivot. This is accomplished by a very
long spring coiled around the pivot. Only a small portion
of the spring's length is needed to apply the required
pressure, thus contributing greatly to the accuracy of the
calibrations.
Avoiding sounds that weren't recorded.
The rotor of every Dual motor is dynamically
balanced in all planes of motion. Each motor pulley and
drive wheel is also individually examined with special
instruments to assure perfect concentricity.
Any residual vibration within the motor is
isolated from the chassis by a three-point damped
suspension. Finally, every assembled Dual chassis is
"tuned" to a resonance frequency below 10 Hz.
The best guarantee.
All these precision features and refinements
don't mean that a Dual turntable must be handled
with undue care. So we're not being rash when we include
a full year guarantee covering both parts and labor
for every Dual. That's up to four times the guarantee
you'll find on other automatic units.
Now, if you'd ke to know what several
independent test labs say about Dual, we'll send you
complete reprints of their reports.
Better yet, just visit your franchised United Audio
dealer. You'll see for yourself that only a Dual performs
precisely likea Dual.
l
i
Dual
United Audio Products, Inc., 120 So. Columbus Ave., Mt. Vernon, N.Y 10553
Exclusive U.S. Distribution Agency for Dual.
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extra dynamic performance
you're
cassette
the -line
superior
than the
If
an audiophile you know what you want-the best
there is. That's why you'll insist on TDK's top -ofEXTRA DYNAMIC (ED). Once you discover ED's
total performance, you won't settle for anything less
cassette with more of everything.
EXTRA DYNAMIC offers audiophiles an entirely new dimension in cassette recording fidelity. Its performance characteristics-shown above on TDK's Circle of Tape Performance
are better balanced and superior to
(see opposite page)
those of any other cassette now on the market, including the
two competitive so-called "hi-fi" cassettes also shown.
-
ED's superior total performance results from use of TDK's
exclusive new "Stagnetite"e (stabilized magnetite) coating
plus a special binder and proprietary techniques. ED cassettes have the industry's highest MOL (maximum output
level), broader dynamic range, extended frequency response,
higher signal-to-noise ratio and other characteristics for
incomparably fresh, rich and full-bodied sound on any recorder, without need for special bias.
Ask your dealer for TDK EXTRA DYNAMIC cassettes when
nothing but the vary best total performance will do. Once
you try ED, you'll wonder why you ever used anything else.
the new dynamic world of
;j4:71DK,
TEI< ELECTRONICS CORP.
755 Eastgate Boulevard,
Garden City, New York 11530
TDK's EXTRA DYNAMIC (ED), SUPER DYNAMIC (SD) and DYNAMIC (D) cassettes are available in
45, 60, 90, 120 (SD & D) and even 180 -minute (D only) lengths, TDK KROM (KR) chromium -dioxide
cassettes are available in 60 and 90 -minute lengths. At quality sound shops and other fine stores.
www.americanradiohistory.com
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more about
TDK's circle of tape performance
....a whole new way to evaluate tape
istics of a "perfect" tape. The closer the characteristics of any cassette tape approach those of the
ideal (the larger and more regular the pattern),
the better the sound reproduction capabilities of the
cassette. The goal is to reach the outer circle.
Compare TDK's well-balanced characteristics with
those of the two leading so-called "hi-fi" competitive
cassettes and a typical conventional tape. Judge for
yourself which provides the best characteristics for
true high fidelity performance.
ability to provide "real -life" sound reproduction depends not only on its MOL (maximum output
level) values and the familiar frequency response
characteristics, but also on the value and proper
balance of a number of other properties. TDK has
arranged the twelve most important tape characteristics on their exclusive CIRCLE of TAPE PERFORMANCE diagrams, shown below. Each of the radii
represents one of the twelve factors, and the outer
circle represents the ideal, well-balanced character A tape's
SD
ED
4«N
®
_
o
o
EXTRA DYNAMIC
for the discriminating audiophile, an
entirely new dimension in cassette re
cording fidelity. Vastly superior to any
other cassette, with unmatched performance on any deck. 45, 60 and 90 minute lengths.
1
-MOL @ 333Hz
333Hz
8kHz
2 -Sensitivity @
3 -Sensitivity @
Competitor A
O
.
.,
O
0
,o
DYNAMIC
SUPER DYNAMIC
excellent hi -fidelity at moderate prices,
with well-balanced performance characteristics superior to most "premium"
turned the cassette into a true high f idelity medium. Outstandingly clear,
crisp, delicate reproduction of the complex characteristics of "real -life"
sound. 45, 60, 90 and 120 -minute
lengths.
4 -Sensitivity @
5 -MOL @ 8kHz
7 -Bias Noise
8 -Print -Through
12.5kHz
9 -Modulation
6-Erasability
Competitor
B
o
,e
Noise
cassettes. 45, 60, 90, 120 and 180 the world's only 3 minute lengths
hour cassette.
-
10 -Output Uniformity
11
-Uniformity of Sensitivity
12 -Bias Range
Typical
Conventional
Cassette
O
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O
ED'S EXCLUSIVE NEW "STAGNETITE® COATING
TDK EXTRA DYNAMIC is the world's only tape with a
magnetic coating of "Stagnetite". The coating consists of microscopically fine particles of stabilized
magnetite in a special binder. Magnetite is a material
with magnetic properties which make it ideal as a
recording medium, except that in its natural state it is not
sufficiently stable. TDK discovered a way to permanently
stabilize magnetite particles; the result (Stagnetite) is a
perfect coating material for magnetic recording tape,
contributing to ED's unrivaled "real -life" sound reproduction capabilities.
THE IMPORTANCE OF HIGH MOL
TDK's EXTRA DYNAMIC tape has the highest MOL values
of any cassettes on the market today. MOL means maximum output level, and is perhaps the most important
single characteristic of a recording tape. MOL is the output signal level resulting from an input signal which produces 5% distortion in the output. A tape with high MOL
can be recorded at higher input levels without audible
distortion on playback. High MOL lets you faithfully reproduce all the complex transient phenomena, subtle
overtones and important harmonics that give the original
sound its natural warmth, richness, depth and feeling.
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Fig. 3-The 8050A Real Time Analyzer, a device which provides continuous monitoring of sound energy levels in one
third octave bands. The response, which is updated each 30
milliseconds, can be viewed in either fast or s/ow modes.
eleven vertical slide controls which allow the user to tailor
his system by ear. They are indeed useful devices, consider-
ing the variety of monitoring conditions between studios and
the resultant spectral variations in records.
A typical example of a t/ -octave equalizing system is shown
in Fig. 1. This device, the Altec Model 729 Acousta-Voicette,
enables the acoustical contour to be continuously and
smoothly manipulated between the frequency extremes of 63
Hz and 12.5 kHz. It is a stereo unit and is normally inserted
at the tape-out/monitor-in terminals of a typical stereo preamplifier or receiver. The Model 729 has the normal tapein/tape-out monitoring facility which provide total flexibility in interfacing this device with a high -quality stereo
system.
Typical of a one-octave wide equalizer is the SAE Mark
VII Octave Equalizer. This device is available in a stereo
Fig.
4-Filter
response curves for the 8050A Analyzer.
model capable of handling the frequency range from 40 Hz
to 20 kHz. Another octave -wide device is the Shure Model
610 Equalizer. Whereas the SAE device is a graphic equalizer,
offering peaking as well as dipping functions for each vertical
slide control, the Shure device, like the Altec 729 offers a
family of combining -type attenuation -only curves. Figure 2
shows the SAE Mark VII along with a family of typical
response curves for the device.
Instrumentation
Real time analysis has greatly simplified the equalization
process in both the consumer and professional areas. The
Altec Model 8050A Real Time Analyzer is shown in Fig. 3.
The device, introduced in 1971, has reduced the cost of
real-time analysis to almost one-third of what it had formerly
been, and this means that hi-fi dealers as well as professional
sound contractors can perform detailed equalization at
moderate cost to the consumer as well as moderate investment for themselves. Figure 4 shows the response curves of
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2012
guaranteed to improve any fine stereo system!
Now, in a few minutes, you can accurately "tune" the frequency response
of your stereo system and room environment to a flat ±2db! All you
need are your own ears and the 20-12 (with its step-by-step instruction
record) to transform any stereo system and room environment into an
acoustically -perfect concert hall! Or, to provide any special acoustical
effects you desire! The 20-12 enables you to instantly compensate for
frequency response variations, in system and room.
PATENT -PENDING design combines the best features of expensive commercial equalizers: Toroidal and ferrite -core inductor passive circuitry,
plus active transistor circuits and active master level control circuits, provide accurate linear response in "problem" listening areas. Allows a full
24 db range of equalization for each of the 10 octave -bands per channel,
plus an additional 18 db range of full -spectrum boost or cut to compensate for acute response non-linearities in the
entire recording -reproducing process.
SPECIFICATIONS and SPECIAL FEATURES
TOROIDAL and ferrite -core inductors, ten octave-bands per channel.
FREQUENCY response: ±% db from 20-20, 480 Hz at zero setting.
HARMONIC DISTORTION: Less than .1% THD @ 2 v., Typ:.05 %
@1
v.
IM DISTORTION: Less than .1% @ 2 v., Typ: .05% @ 1 v.
SIGNAL-TO-NOISE RATIO: Better than 90 db @ 2 v. input.
INPUT IMPEDANCE: Operable from any source 100K ohms or less
- (any Hi-Fi Pre -amp, Receiver or Tape Recorder.)
OUTPUT IMPEDANCE: Operable into 3K ohms or greater
Hi-Fi Amp, Receiver or Tape Recorder.)
CIRCUIT BOARDS: Military grade G-10 glass epoxy.
RESISTORS: Low -noise selected carbon -film.
RANGE: 12 db boost and 12 db cut, each octave.
- (any
MASTER OUTPUT LEVEL: "Frequency -spectrum -level" controls for
Check No. 57 on Reader Service Card
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$299.50
left and right channels continuously variable 18 db range, for unity
gain compensation from minus 12 db to plus 6 db.
MAXIMUM OUTPUT SIGNAL: variable Master 'frequency spectrum
level" Controls allow adjustment of optimum output voltage for
each channel, to exactly match amplifier capability, up to 7 v.
SIZE: designed to coordinate with receivers, comes installed in
handsome walnut -grained wood receiver -size case, (5% x173/. "x11 ").
WARRANTY: 2 -year parts and labor.
\
the individual filter sections which are displayed on the
screen of the 8050A.
The Interaction Between The Loudspeaker and
Listening Room
A typical high -quality loudspeaker system located in a
20' x 15' x 9' living room may present a pre -equalization
response as shown in Fig. 5-A. A pink-noise generator, which
provides a random noise signal exhibiting equal energy -per octave, is applied to the monitor input of the system.
One may be surprised to see such a wide range of response
-on the order of 16 dB-but this is typical of many high quality systems in many rooms. The inverse curve was introduced with the Altec 729 equalizer flat out to 8 kHz, with
a 6 dB/octave roll -off above that point. Some kind of controlled high frequency roll -off is desirable to compensate,
at least in part, for the fact that most records are themselves mixed and mastered over systems exhibiting a degree
of high frequency roll-off. This is a standard situation
throughout the industry; what is not standard is the precise
degree of roll-off.
The 16 dB response variation, once it has been corrected,
calls for a 40 -to -1 power ratio, and consequent power reserve, between the equalization extremes. Specifically, in
order for the left channel of the system of Fig. 5 to produce
the same response level at 40 Hz as it does at 250 Hz, it
will require 40 -times more power; if 2.5 watts are sufficient
at 250 Hz, then 100 will be required at 40 Hz. It has long
been observed that the prime problem areas in most equalized systems are the insufficient provision of low frequency
power as well as the inability of the loudspeaker to handle
such powers. As we have said earlier, only good systems can
be equalized.
FREQUENCY IN HERTZ
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AL
EC
ACOUStA-VOICETTE'' ACOUSTIC
for the critical audio connoisseur. The
unique REFLECTROSTATIC" design, combined with low distortion acoustic suspension transducers, provide exceptionally
smooth frequency response over the entire
spectrum, with unprecedented power handling capabilities. The exclusive Protection
Logic circuitry allows the SC-12ES to be
used with amplifiers of modest power
capacity, as well as with the latest, high
-
50
-
wattage units available. Designed
as a
bookshelf or floorstanding speaker in 18
28 x 14" Walnut cabinet.
in matched pairs
x
"Pre -Equalized" Loudspeaker Systems
More and more, we are seeing loudspeakers in the marketplace with their own complementary active equalizers. These
devices, placed just ahead of the power amplifier, provide
fairly broad correction for the most commonly met loudspeaker/room difficulties. The usual problem is shown in
Fig. 5; it is the tendency of most room/loudspeaker combinations to exhibit a substantial peak in the 80 to 200 Hz
range with a fall -off of bass response below 60 Hz.
The difficulty is largely one of the architectural acoustics;
the majority of living rooms are too small to propagate extremely low frequencies as efficiently as the shorter wave
Electrostatic Transducers are universally
acknowledged to be the very finest available source for perfect audio reproduction.
The 12ES utilizes both the front and rear
radiation through the Soundcraftsmen
engineered Reflectrostatic' °' rear -wave
doubler. Only by experimentation and use
of the controls can the listener realize the
optimum results of any speaker system,
and that is why the 12ES includes a control
for each segment of the frequency
spectrum.
The compactness, control versatility,
power -handling capacity, and low price represent a major breakthru in optimum per-
formance/size/price specifications for
sophisticated home high fidelity.
SPECIFICATIONS and SPECIAL FEATURES
FREQUENCY RESPONSE: -: 3 db, 30 Hz - 20 KHz
RMS POWER REQUIRED: Min. 20 watts
RMS POWER HANDLING: Peak - 200 watts. Cont. 150 watts
CROSSOVER POINTS: 500 Hz, 1,000 Hz.
CROSSOVER DESIGN: 4 LC Networks
ULTRASONIC LIMITER: 15 KHz to 100 KHz
NOMINAL IMPEDANCE: 8 ohms
-
-
RESPONSE CPART
Fig. 5-Typical before and after acoustical response curves
for a stereo system in a normal environment. Equalization
provided by an Altec 729 Acousta-Voicette monitored by
an 8050A Analyzer.
New W -Type ReflectrostaticTM
Doubler Dispersion Element
1 KHz-30KHz Bi -Polar Radiators
500Hz-1KHz Dynamic Midrange
20Hz-500Hz Acoustic Suspension
15KHz-100KHz Ultrasonic Limiter
20Hz-30KHz 4 -Way Equalization
The Soundcraftsmen SC-12ES is our latest
"State of the Art" product to be introduced
4
-
SC-12ES Ref/ectrostaticTM
cee
$399
4
WOOFER: 1 7" Acoustic Suspension dynamic with Alnico magnet.neoprene surround.
MIDRANGE- 5" sealed back, controlled resonance, damped surround.
TWEETERS: Retlectrostatic'... elements 144 sq. inches of bipolar
radiation with back -wave doubling. Polarization over 1000 volts
d.c. Distortion less than ,5%.
CABINET SIZE: 28" x 18" x 14"
SHIPPING WEIGHT: 76 lbs.
Check No. 68 on Reader Service Card
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.
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Fig. 7-Electrical response curves typical of the active equalizer portion of the Concept EQ System.
Fig.
6-The Altec "Concept EQ" loudspeaker
system.
sponse curves are shown in Fig. 7. Here we show the flexilengths of the mid -bass and lower mid -range regions. The bility of high frequency tailoring and suppression of an 80
high frequencies are furthermore attenuated due to furniture, to 150 peak in the solid curves; the dotted curves show the
carpet, and drapes. The usual sound is described as "thick range of extreme low -frequency boost. Actually, the equalizer
and muddy," without the "impact of really massive bass." portion of the Concept EQ system is a welcome adjunct to
Any loudspeaker designed for flat response in an anechoic most wide-range systems, and is separately available at a
chamber will suffer the same fate in such an environment. cost of $125.
One interesting practical solution to this problem has
Another very well-known system with an integral active
been met by the Altec Concept EQ, shown in Fig. 6. This equalizer is the Bose 901. Here, the design aim was to prosystem is designed basically as a flat system in terms of its vide the electrical equalization necessary for an array of
energy output into a uniformly absorptive environment. It nine loudspeakers to produce a flat spectral output under the
is equipped with a 3 -control variable equalizer, whose re- specified mounting conditions of eight speakers facing a re -
Words
or music?
We'll be glad to tell you all about the millivolts and dB's
and watts in Altec AM, FM Stereo Receivers. Or talk to
you about things like low distortion and sensitivity and
The Altec 725A AM/FM
separation. Because when it comes to the specification
word game, our receivers stand toe to toe with the very
best of them.
But as important as good specs are, what you really
end up buying when you get a stereo receiver is its
sound-the unique way it translates the complex information or today's dynamically recorded source material
into m:tsic that truly satisfies your ear.
That's why we invite you to compare Altec AM/FM
Stereo Receivers with any other comparably priced
receivers on the market. Compare specifications, to be
sure. And features. And dollar for dollar value. But most
of all, compare sound.
The sound of experience
1515 S. Manchester, Anaheim. Calif. 92803
Stereo Receiver
AL-TEC,
OF 4LTEC CORPOR4TOON
For complete information on Altec AM/FM Stereo-Receivers,please write to the Audio Information Group at Altec.
www.americanradiohistory.com
AmericanRadioHistory.Com
flective wall of large dimensions at a distance of about one
foot. The Bose equalizer provides a variety of high -frequency
tailoring and a "below -40 Hz" cut-off function for alleviating
excessive record rumble and other sources of amplifier overload. There is no specific tailoring of the mid -bass response
or adjustment to varying room acoustics. Figure 8 shows the
range of the Bose equalizer.
Hints for the Audiophile
So far, we haven't been too encouraging. We've told you
how good sound system equalization is-but we've also told
you how expensive it is and how difficult it may be to make
it perform properly. The well-to-do audiophile in a large
urban area can always purchase an Acousta-Voicette for the
sum of $875 from a qualified Altec sound contractor or hi-fi
dealer and be assured that the equalizer will be properly
adjusted.
On a less ambitious level, he can buy an equalizer, either
one-third or one -octave, and equalize it himself by ear-or
through the use of any of a number of phonograph discs
made for the purpose. Such records date back to early
issues of the famous CBS Laboratories Test Record Series,
and in recent times the Altec Acousta-Voicing test record has
certainly been the best known. This record presents carefully
calibrated one-third noise bands covering the range of frequencies which can be adjusted by the Acousta-Voicette. The
record is designed to be played back via the normal RIAA
playback response, and monitored with a Sound Level Meter
(SLM). With this device, the sound pressure output from each
band is carefully noted and charted. The accuracy of the
Acousta-Voicing test disc is .'A dB from 50 Hz to 2000
11/2 dB above 2000 Hz.
Hz and
Md0001CY
Fig.
IM
CYüL .EE SECOND
8-Electrical response curves of the active equalizer
portion of the Bose 901 loudspeaker system.
An audiophile wishing to equalize his own system with this
disc should observe the following:
1. Make sure that the SLM is operating in its flat mode-the
so-called "C" scale.
2. Make sure that the phonograph cartridge is a flat oneand in excellent condition. The better crop of today's cartridges working into good preamps just about guarantee this.
If the cartridge is not flat, then the resultant equalization will
be "biased," so to speak, in favor of the phonograph cartridge, and other input signals, a tape recorder for example,
will be reproduced with an improper contour.
............. '714
1=0
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The Altec 714A AM/FM Stereo Receiver
The Altec 704A AM/FM Stereo Receiver
Before you make your final selection, listen to the
music. (Then read the words if you need more convincing.) Ask your nearest Altec dealer to demonstrate
the Altec AM/FM Stereo Receiver that fits your budget
with the loudspeakers of your choice. Listen at background levels and listen at concert hall intensity. Listen
to the very lowest lows and the very highest highs.
Listen for smoothness and accuracy and lack of coloration. And listen carefully.
The difference you'll hear
is the sound of experience.
The Altec 710A AM/FM Stereo Receiver
Check No. 5 on Reader Service Card
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41.111111.111Miliffla
FREQUENCY
RIM
Why the Response Should Not Be Flat
IN HERTZ
®
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contour for
9-Optimum acoustical
equalization of home
systems.
Take your time; don't try to equalize too quickly. Adjust a
few controls at a time-and then only slightly. Special graph
paper is available to facilitate plotting of the curves, and
the Altec dealer who can provide the Acousta-Voicette can
also provide the disc and the graph paper.
4. Don't try to equalize the system to a flat contour. Let it
roll off above 2 kHz at about 3 dB -per -octave. This is shown
in Fig. 9. A tolerance of ± 21 dB can usually be maintained over the range from about 200 Hz up to 8 or 9 kHz,
if sufficient care is taken. Below 200 Hz, the effects of room
resonant modes, with their characteristic peaks and dips, tend
to dominate the response. In the region below 200 Hz we
simply have to accept dips in the response of perhaps 4 dB;
peaks should be held as low as possible. Always perform the
equalization with the SLM located at the prime listening
3.
position.
Dealers:
WEST
The New
Garehime's Music Co; Las Vegas, Nevado
Paulson's. Tacoma, Washington
Stereo Northwest; Seattle, Washington
Hawthorne Stereo; Portland, Oregon
Hi Fi Sales Co ; Mesa. Arizona
House of Stereo, Tucson. Arizona
Audio Arts; Livermore, Calif
Audio Vision; Ventura, Calif
Audio Vision; Santa Barbara, Calif
International Sound, Modesto, Calif.
Kustom Hi Fi: Burlingame, Calif
Calif Hi Fi; Van Nuys, Calif
Calif Hi Fi, City of Commerce, Calif
Mal Sykes TV & Hi Fi; Sacramento.Calif
Mission Electronics: Riverside, Calif
Shelley's Audio Inc.; Panorama City.Calif
Shelley's Audio Inc.; Los Angeles, Calif.
Shelley's Audio Inc.; Berkley, Calif.
Sound Company. San Diego. Calif.
Stereo City, Eureka, Calif
Woodland Stereo. Woodland Hills, Calif
SOUTH
W R. Gibson Audio: New Orleans, La.
Audio Specialty; Baton Rouge, La.
Arnold & Morgan Music Co.; Garland, Texas
Audio Systems of Dallas: Texas
Audio Concepts, Unitd.: Denton, Texas
Sounds Unlimited: Corpus Christi, Texas
Toby Corp. of America: Fort Worth. Texas
Westpark Electronics. Arlington, Texas
Potomac Systems; McClean, Virginia
Interiors Plus Sound; Fort Lauderdale. Florida
Bowden's Audio; Athens. Georgia
At least at the present time, the acoustical response of a
playback system, whether in the studio or in the home, should
exhibit a rolled off response above 1 or 2 kHz. Let us see
why this should be the case by going all the way back to the
recording studio and examining the consequences of flat
monitoring of recorded product. At this point, the author
quotes from a paper given at the AES Convention in Rotterdam, February 1973:
"Another important consideration in equalizing monitor
systems is the precise tailoring of the high -frequency response. The question of 'flat vs. rolled -off response has
been discussed in some detail, and there is a general consensus among recording engineers that some sort of high
frequency roll -off is desirable. The reasons, of course, are
obvious; most home playback equipment exhibits substantial high -frequency roll -off at normal listener's positions,
and a recording monitored and equalized over a system
exhibiting the same kind of roll-off will convey most of
the musical values the recording producer had in mind.
On the other hand, a recording monitored and equalized
on a flat system would surely sound dull and lifeless
played over the rolled -off system. The answer to the problem is not to make all systems flat; that would call for a
reassessment of present disc equalization standards, not
to mention the problems of playback equipment design and
obsolescence. Rather, the answer is to be found in standardizing on a degree of roll-off, with reasonable tolerances, which can be met by the manufacturers of home
playback machinery and studio monitors alike."'
1.
J. Eargle: "A Summary of Recording Studio Monitoring Problems" given
at the 44th AES Convention in Rotterdam, February 1973.
Columns
MIDWEST
Audio Concepts; South Bend, Ind
Community Electronics: Lafayette, Ind.
Appletree Hi Fi: Dekalb. Ill
George Fillip Music Co; Aurora, Ill.
Gill Custom House, Inc., Chicago, Ill.
The RTR columns are a new concept in transducer
application which by design exhibit a broad
loudspeaker characteristics.
of
preferred
band
Each elegant walnut enclosure houses multiple
ultralinear butyl edge suspension woofers; one of
which is planar resistive loaded. This technique
is accomplished by floor loading a woofer through
a predetermined planar slot, which yields maximum
acoustic low frequency coupling, increased damping, and a smooth rolloff above 100 Hz. This
powerful low frequency concept is the cornerstone of the new RTR column speaker system.
Write for complete information and specifications
for:
MODELS 180D and 280 DR (COLUMNS)
MODELS ESR 6 and HPR 12
Patent applied for
Tech Hi Fi; Chicago, Ill.
Audio King, Inc.; Minneapolis, Minn.
Jensen's Stereo: Burnsville, Minn.
Roman's Audio Classic, Minneapolis,
Minn.
Electronics Etc.; Burlingame, Mich.
Stereoland: Fargo, No. Dakota
Frey's Electronics; Aberdeen. So
Dakota
Affiliated Audio Engineering; Massilon,
Ohio
Audio Warehouse; Niles. Ohio
L
& B Sales; Columbus, Ohio
Hoffman's House of Stereo; Brookpark,
Ohio
The Stereo Shop; Cedar Rapids, Iowa
EAST
Paul Heath; Rochester. N.Y
Sego Electronics; MY.. N.Y
Suffolk Audio; Islip. N. Y
Utica Audio; Utica, N.Y
Stereo Emporium; Buffalo, N.Y
Lawrence Sound Depot: Flemington.N.J
Mainline Music Co.; Stroudsburg.Penna.
Tech Hi F, Randolph, Mass.
RTR Industries, Inc., 8116 Deering Ave., Canoga Park, CA 91304 (213) 883-0116
Check No. 45 on Reader Service Card
AUDIO
62
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NOVEMBER 1973
The 400 millisecond miracle.
Most people
seem to take for
granted the
smooth, effortless way in which a Revox works.
And that is as it should be.
For a great deal of time, effort and
sophisticated engineering have gone
into translating extremely complex
function into lightning quick, responsive operation.
For example, when you press the
play button of a Revox, you set in motion a sequence of events that take
place with the precision of a rocket
launching.
It begins with a gold plated contact
strip that moves to close two sections
of the transport control circuit board.
Instantaneously, the logic is checked
for permissibility. If acceptable, a
relay is activated.
Within 15 milliseconds, power is
supplied to the pinch roller solenoid,
the brake solenoid, the back tension
motor, a second relay and, at the same
time, the photocell is checked for the
presence of tape. If present, Relay
One self -holds.
Elapsed time, 25 milliseconds.
At 30 milliseconds, Relay Two
closes and puts accelerating tension
on the take-up motor.
The logic checks are now complete
and power is available to actuate all
necessary functions.
From 30 milliseconds to 300 milliseconds, mechanical inertia is being
overcome and the motors and solenoids are settling down.
By 300 milliseconds, the brakes have
been released, the pinch roller is in
contact with the capstan shaft, the
tape lifter retracted, the playback muting removed and the motors have
come up to operating speed.
At 350 milliseconds power is cut off
from Relay Two, which changes over
to another set of contacts, releasing
the accelerating tension on the take-up
motor and completing a circuit
through Relay One that, in turn,
restores normal tension to the
take-up motor.
Total elapsed time, 400 milliseconds.
The Revox is now in the play mode.
And it's all happened in a fraction of
the time it takes to read this sentence.
The 400 millisecond miracle.
More proof that
Revox delivers
what all the rest
only promise.
Revox Corporation 155 Michael Drive, Syosset, N.Y. 11791. Calif.: 3637 Cahuenga Blvd. West, Hollywood 90068
England: C.E. Hammond & Co., Ltd., Lamb House, Chiswick, London W4 ZPB. Available in Canada.
www.americanradiohistory.com
AmericanRadioHistory.Com
The Workbench
all inputs are converted by the range switch. This basic voltage-protected by a pair of diode -connected bipolar transistors-is fed. to a linear IC and its output charges a capacitor, which is then discharged at a constant rate. The time
required to discharge the capacitor is measured by the number
of cycles of the 40,000-Hz clock oscillator that it takes to
discharge it. This action takes place every 200 milliseconds,
and the number of cycles of the clock that pass during the
discharge period are counted, decoded, and displayed. Measurement of resistance is done by passing a specific current
through the unknown and measuring the voltage drop across
the unknown, so the instrument is still a voltmeter. For a.c.
measurements, the input is converted to d.c. by an average sensing, rms-calibrated converter. Thus the instrument is
always a voltmeter, regardless of the quantity it is measuring.
This is, of course, true of any vacuum -tube multimeter, and
with the except of measuring shunts across the meter movement, this also applies to any multimeter. Even then, one
could say that the meter movement itself is actually a voltmeter that draws a finite amount of current when making any
Heathkit IM -102 Digital Multimeter
MANUFACTURER'S SPECIFICATIONS
D.c. voltmeter: 5 ranges -200 mV, 2V, 20V, 200V, and
1000 V. Accuracy: ±0.2%± 1 digit with furnished calibrator; +0.1%-i- 1 digit with lab calibration. Overload protected. Ohmmeter: 6 ranges -200 ohms with 1 mA test
current; 2000 with 100 µA; 20,000 with 10 pA; 200k with
10 µA; 2.0 megohms with 1 µA; 200 megohms with 100 nano amps. A.c. voltmeter: 5 ranges (same as d.c. voltmeter).
Accuracy: 0.75% ± 1 digit with calibrator from 40 Hz to
10 kHz; increasing to maximum of 1.5%-i- 1 digit on 1000
V range. Overload protected. D.c. ammeter: 5 ranges -200
µA, 2 mA, 20 mA, 200 mA, and 2A. Accuracy: ±0.5%± 1
digit for 2 -amp range, better on other ranges. Overload protected to 3 amps. A.c. ammeter: 5 ranges (same as d.c.
ammeter) Accuracy: better than 1 .5%± 1 digit on all ranges.
Display: Maximum count, 1999, with overrange indication
automatic beyond 1999; polarity indication, automatic
(on d.c. ranges). Numeric display by side-viewing
or
neon glow tubes with integral decimal points. Dimensions:
3 in. H x 7 in. W x 7.9 in. D. Weight: 8 lbs. Price: $229.95.
"-"
"+"
Anyone who has ever done any servicing or experimenting
with either linear or digital IC's will certainly welcome this
instrument. Having made hundreds of measurements with the
older Heathkit IM -18 vtvm, the writer has been annoyed by
the need for switching from "+" to "-" every time the probe
was moved from one point to another (almost). The automatic polarity indicator eliminates this requirement and thus
speeds up the measurement procedure appreciably. In comparison with the older vtvm-which has given many years of
reliable service-the increased accuracy of reading the instrument is noticeable, and especially with solid-state devices,
the minimum range of 200 mV is extremely useful. This
observer never could see the reason for having a digital instrument until finally putting one into daily use-and now
would not be without one. The IM -102 is not inexpensive
compared to the IM -18 which is priced at $29.95, but it is
a worthwhile investment in any case, and does not require
occasional replacement of the ohmmeter battery.
Principle of Operation
The IM-102-and most other digital multimeters, for that
matter-combines analog and digital techniques. The basic
input range-either 200 mV or 2 V-is the voltage to which
measurement.
It should be noted here that the input resistance of the íM102 is considerably higher than in the average vtvm on the
two lowest ranges. On the 200 mV range, the input resistance
is greater than 100 megohms, and on the 2 -volt range it is
greater than 1000 megohms, whereas most vtvms have a constant input resistance of 11 megohms. On the three highest
ranges, input resistance is 10 megohms, which is approximately
the same as with vtvms. Similarly, the test current ranges from
mA on the 200 -ohm range to only 100 nanoamps on the
20-megohm range. On the a.c. voltage ranges, the input impedance is constant at megohm shunted by 150 pF, and the
voltage in the current -measuring modes is only 0.2 volts for
both a.c. and d.c.
The main differences between the digital instrument and its
counterparts is in the method of displaying the results. In an
analog instrument, the display is always on the scale of a
meter-usually with a movement sensitivity of 50 microamps
for a 20,000 -ohms-per -volt instrument or of 200 µA for a
5000 -ohms -per -volt model. In the digital instrument, the actual
voltage measurement is done by analog techniques, and the
readout is supplied by display elements-in this case, by neon
tubes of the "Nixie" type. Three such tubes are employed,
each with full display of numerals from 0 to 9, which accounts
for a maximum display of 999. The fourth digit-required to
provide a display of 1999-is simply an ordinary neon tube
with elements of the same length as the height of the numerals in the display tubes.
Assuming the determination of the number of cycles of
the 40 -kHz oscillator that pass during the measurement of
the discharge time of the integrating capacitor, and repeating
this measurement every 200 milliseconds (that is, five times
per second), there are 8000 cycles to work with during each
measurement period. The actual number of cycles elapsed are
counted, fed into buffer-storage units, and then fed to decoder-drivers which actuate the three numerical display tubes.
Separate dual flip-flops actuate bi -polar transistors which
cause the fourth digit (the "1") to be illuminated, the "over"
lamp to light up, or to display the "+" or "-" lamps for
d.c. polarity.
The normal display range is 1999, which could be either
199.9 µA, or mV, 1.999 mA or volts, 19.99 mA or volts, 199.9
mA or volts. The maximum d.c. voltage range is 1000; on
1
1
AUDIO
64
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AmericanRadioHistory.Com
NOVEMBER 1973
gpEcui
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4'OIMENSIONAL AMPLIFIER
NAFigpy
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dynaco 4-d
amp
kit
Value-the
SCA-80Q is the only 4-D amplifier in kit form and for the
same cost as a similar two channel amplifier. From a buillt-in ce -matrix
circuit at the output of the amplifier. connect four speakers (such as the
very popular DYNACO A -25s). Uncover hidden concert hall ambience in
many conventional two channel discs, tapes and FM broadcasts and
recreate the original sonics with new 4-D recordings. Or use two
speakers now for stereo and add others later. 40 watts RMS per channel. simple assembly, careful engineering, low distortion and superb
versatility go together to give traditional DYNACO excellence.
$179.00 kit; $259.00 assembled
dulNaC0 INC_
Also available in
Division Tyco
3060 JEFFERSON ST., PHILADELPHIA, PA. 19121
Canada from DYNACO OF CANADA, LTD., Montreal, 760, Quebec, Canada
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The various indicators are visible through the smoky plastic
front panel window with the designations visible as illuminated to indicate the +, -, and "over." A pressure sensitive
light shield is furnished to provide a black background behind
the display tubes.
On the whole, the instrument goes together with usual
knob, with twelve positions, is labeled in volts and mA from
1000 to 2, then 200 mV or µA, with six positions labeled from Heathkit ease. The rear panel is screened with a space for
200 to 20M for ohms. The initial position is the power -off the Heath label which is put on to cover the lettering for the
condition. Three banana jacks are mounted on the front line voltage for which the instrument is not wired, leaving
panel-red for volts and ohms, black for common, and white the line voltage for which it is wired visible. Fuses mount oil
for mA. Note that the instrument measures both direct and the side panel to protect the line voltage supply (1/4 amp) and
alternating voltages and currents, with the conversion from for the voltage -measuring circuits (Vs amp) and the current a.c. to d.c. being done by the a.c. converter circuit board on measuring circuit (3 amps).
The a.c. line cord is a three -wire assembly with the usual
which are mounted one linear IC, one bi-polar transistor,
and one FET, four diodes, and two adjustable controls for three -terminal plug on one end and a female receptacle on
the other which plugs into the male connector on the rear
calibration.
The power supply, integral with the main circuit board, panel. The housing consists of a top cover and a bottom
consists of the transformer (mounted on the rear panel) which cover which are held in place by the side trim strips. The
feeds 54 volts center tapped to a full -wave rectifier, 12.7 handle, with its plastic grip, is detented to hold it in any of
volts center tapped to another full -wave rectifier, and 102 three positions-for carrying or for a tilted position on the
volts to a half-wave rectifier circuit to supply the operating workbench.
voltage to the display tubes and the neon indicator tubes. The
Calibration
22 volts d.c. following the rectifiers feeds the collector of a
While the instrument may be calibrated using laboratory
power transistor which is controlled by another transistor
the average constructor will use the d.c. calibrator
equipment,
which is referenced by two Zener diodes to furnish 2, 12 volts
with
the instrument. This device is a small circuit
furnished
to the linear IC's and to most of the transistors in the unit.
are mounted a 1.35 -volt mercury cell, three
which
board
on
The 6.75 volts d.c. following the low -voltage rectifiers is fed
and
two adjustable ones (one is factory set).
resistors,
fixed
to a Darlington -connected transistor (all in one package) and
an accurate source of 0.2 volts which is
provides
This
device
referenced by another Zener diode to supply 3.5 volts to the
200 mV range of the unit. Connecting
the
to
calibrate
used
digital IC's. The 102 -volt winding is rectified by a single
to the 3.5 -volt test point on
from
the
calibrator
one
lead
diode to furnish 95 volts to the display tubes. This winding
adjustment
of the variable resistor
the
instrument
permits
the
also supplies either a.c. or d.c. at an adjustable 9.0 volts for
2.0 volts which is used to calibrate the
an
accurate
to
provide
use in the calibrating procedure. In all, the circuit employs a
total of 19 IC's (three of them linear), 18 transistors, six Zener 2 -volt full-scale position.
The a.c. calibrator circuit is built directly into the instrudiodes, and 19 diodes of varying characteristics to actuate the
and permits accurate adjustment of the a.c. circuits,
ment
three digital display tubes and the four neon lamps which
first
making an adjustment to provide an indicated 9.0
after
indicate polarity, overrange, and the "1" of the digital display.
volts d.c. with the calibrator switch in the d.c. position. Possibly
hard to explain but simple to do.
We assembled the instrument in about 10 hours with no
Construction
attributable to Heath, and only one attributable to
problems
The layout of the instrument is interesting in its simplicity.
The range switch consists of an eleven-wafer switch which is ourselves-we connected the black "common" lead to where
designed for printed -circuit board use, and which is first the "hot" red lead should be and vice versa, resulting in some
disassembled to "straddle" the a.c. converter circuit board, odd indications until we found the trouble and corrected it.
then installed on the main circuit board and its 25 contacts After that, the unit worked just as expected. While the specifications seem to indicate that the a.c. response is somewhat
soldered in place. Several other connections are made to the
limited
in frequency response, we compared the voltages
puts
switch by wires and by components. This arrangement
the a.c. converter circuit board some two inches to the rear of indicated with those indicated on a Heathkit a.c. VTVM,
model IM-38. Practically the same indications were observed
the front panel, with a number of other connections making
at any frequency up to 100,000 Hz on both instruments, and
a sturdy mounting. The four-wafer function switch has 24
both coincided with the output indications on the IM -72 audio
which
contacts which solder similarly to the circuit board, and
generator. It would probably be desirable to make a complete
is entirely in front of the converter board.
check on any individual instrument to make sure that this
on
with
foil
connections
The circuit boards are glass epoxy
performance is duplicated, but it was a pleasant surprise to
both sides, and with appropriate "solder-through" points. The
find such an agreement throughout the audio spectrum in
which
are
first
soldered
DIP IC's mount on Molex connectors
spite of the specifications. Maybe we were just lucky, but
in place in strips of seven or eight and then the connecting
that is what we found.
for
the
purfurnished
backbone is broken off, using a "tool"
The digital multimeter is a real joy to use when working
pose. The three linear IC's are housed in the familiar TOon
circuits which employ both positive and negative polarities
connectors
in
series
of
female
a
99 case, and they mount
which accept the pins of the IC in the same manner as a as is common with IC circuits, and being able to read voltage
tube socket. Most of the bi -polar transistors simply solder to to as low as 1 mV is most helpful in almost any transistor
circuits. The IM -102 is an exceptionally useful instrument, and
the foil, in the usual way for installing transistors. Two dual
after living with one for a few days, the user would never
as
mount
in
the
connectors
with
six
pins,
transistors, each
used for the linear IC's. The three digital display tubes mount give it up for the older analog instruments. The addition of
current-measuring capability to the usual voltage -measuring
in sockets which are soldered to the circuit board, and the
qualities of the average multimeter makes it an important
neon single tubes for the "1" and the overrange indicator are
instrument for any workshop or laboratory. Try it-you'll
also soldered to the circuit board, being positioned by a plastic
C. G. McProud
like it!
light shield which holds them in the proper locations. The
Check No. 70 on Reader Service Card
+ and - indicator lights also mount in the plastic shield.
a.c. it is 500; and for the current measuring positions it is
2 amperes -1.999 A plus the "over" light. Operation is quite
simple, since there are only two knobs-one controls the
function, with positions marked mA and volts/ohms in the
d.c. section and V and mA in the a.c. section. The other
AUDIO
ÓÓ
www.americanradiohistory.com
AmericanRadioHistory.Com
NOVEMBER 1973
THE 800+
IS.
The world's most advance
multichannel receiver is a production reality. It is available in your
area now, or it will be soon.
The Harman/Kardon 800+
multichannel receiver is equipped
with built-in CD -4 circuitry.
Newer, more compact, more
efficient circuitry than standard
industry use.
It is also equipped with built-in
matrix circuitry. Also newer, more
compact, and more efficient.
This means that the 800+ is
able to play all mono, stereo,
and quad systems now. There is
nothing you have to add. No
accessories to buy.
If you're interested in power,
you'll be delighted and astonished
to learn that the 800+ is rated
at a remarkable 22 watts RMS
per channel quad, 50 watts RMS
per channel stereo.
Because unlike most four
channel receivers, the 800+
is equipped with a bridging circuit
that allows you to transfer all the
power to 2 speakers when you
want to play stereo.
A unique phase shift network
is Harman/Kardon's answer to
those who would like to play their
stereo records through four
speakers for an enhanced stereo
effect.
And lastly, the 800+ is another
from a long line of Harman/Kardon
ultra wide bandwidth receivers.
So its phase linearity and
square wave response match the
matchless lab results of other
Harman/Kardon p-oducts.
But important as bench test
numbers are to verify performance,
what really matters in the end
is sound.
Because if you have great
numbers but you don't have great
sound, then the receiver is a
fraud.
And, that, the 800+ is not.
HARMAN/KARDON
55 Ames Court. Plainview, N Y 11803, U S A Also available in Canada
Check No. 28 on Reader Service Card
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Why We Believe the Advent 201
is the Most Satisfying Tape Machine
of Any Kind You Can Buy.
In 1970, Advent decided to do what no manufacturer of tape equipment was doing:
to develop cassette equipment that was not only convenient and fun to use but capable
of making and playing recordings that would be fully comparable to the best open -reel
tapes and LP records. Accordingly, we became the first, and for quite a while the only,
manufacturer to apply such crucial innovations as the Dolby System of noise reduction
and DuPont's chromium -dioxide tape to cassette recording. While developing our highperformance cassette equipment, we also held demonstrations of what was possible in
cassette recording for the public, press, and other manufacturers, and lobbied for
Dolbyized pre-recorded cassettes from the major labels.
The major product to come out of that process was the Advent 201 cassette deck.
The 201, one of the most highly and explicitly praised products in the history of
audio products, has been on the market for two years now. It has literally dozens of
competitors claiming equivalent or better performance.
But we believe it to be not only as good in every way as more recent and far more
expensive cassette machines, but to be as satisfying for the most critical home -recording purposes as any tape machine of any kind. Here are some questions and answers
to help define that satisfaction :
Why Is The 201
Such A Simple Machine?
Because we wanted it not just to be capable of
making excellent recordings but to make it easy
for the listener to obtain its full performance time
after time, recording after recording. Most tape
recorders of all kinds and all prices don't make it
easy for the user to get best results every time or
at all, and many are made needlessly complex to
operate because of too many marginal "features"
that were assumed necessary to make them attractive (or competitive with other machines) in an
audio showroom.
It's important to point out, we think, that Advent
products are designed with far more thought to
satisfying people after they buy than to what
might tempt them to buy in the first place. The
201 has no knob or slider or gauge or indicator
light that isn't a useful feature rather than a sales
feature. But everything conducive to highest -quality recordings and long-term enjoyment is there.
Why Does The Machine Look So
Different From Most Others?
Because it is different, and far more rugged and
reliable than most. It has evolved from a transport
that has been in heavy and hard use for years in
schools, libraries, and other audio-visual applications, and it is likely to last and maintain its
mechanical performance far longer than most cassette machines on the market. It also provides
facilities such as automatic shut-off and complete
mechanical disengagement at the end of a cassette
or in the event of a jammed cassette-with the
latter preventing tape spillage that makes an
otherwise salvageable cassette a hopeless snarl of
tape. And it enables you to shuttle from one mode
of tane motion to another without having to press
the Stop button in between. As a trade for our
configuration, you have to hold onto the Rewind Forward lever while you use it, but its action is so
fast that we have had vanishingly few complaints
from customers about it.
Why Does The 201 Have A Single
VU Meter Instead of Two?
Because that proved, after consideration of all possible approaches, to be best-combining precision
and simplicity. One of the troubles with using two
VU meters in home recording is that they tend to
lead the user to adjust them to read the same on
both channels. In reality, though, the material on
the two channels is usually different, and the
meters shouldn't read equally. Two meters also
produce a tendency to correct for overload or
under-recording by adjusting only the channel
whose meter showed too high or low a level. But if
the channels were balanced properly in the first
place, this puts them out of balance.
The 201's single VU meter, unique in cassette
equipment, scans both stereo channels and instantaneously registers the louder peak on either at a
given moment. The listener first uses the meter,
which can also be switched to read either channel
individually, to set channel balance with a pair of
Input Level controls. Once balance is set, the
meter is set to scan both channels, and final recording level is set or changed with a single Master
Level Control that operates on both channels-
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AmericanRadioHistory.Com
leaving the balance undisturbed. This sequence
provides far more accurate level -setting than is
possible with the overwhelming majority of tape
machines of all kinds.
Not only does the 201's meter read instantaneous peaks (by far the most accurate indicator of
possible overload), but its action is compensated
to indicate the exact point of tape saturation at all
frequencies. On rock music in particular, overload
is most likely to occur and be heard at high frequencies, and most level -indicators on tape
recorders of all kinds don't register full high frequency content.
We know of no metering system more advanced
or effective than the 201's. Most not only aren't as
accurate, but tend to mislead the user.
machines now being publicized-tells us that we
give far more attention to those realities than most
other manufacturers.
Ours isn't the only good cassette machine in the
world, but there is none likely to satisfy you more
in the long run.
Has The 201 Been Changed?
While we were developing the first high-
If you would like more information on the 201,
including its reviews and a list of Advent dealers
where you can hear it, please send us the coupon.
Thank you.
About Advent Chromium -Dioxide
Cassettes:
performance cassette equipment, we became
convinced that DuPont's chromium-dioxide
tape formulation was crucial for optimum
recordings, and began to put it in cassettes
and market it on our own. Advent Chromium Dioxide tapes are made to live up to the quality of the tape they enclose. If one ever jams,
we will either replace it or, if you prefer, do
our best to transfer a valued recording to
another cassette.
Advent Chromium -Dioxide tapes cost no
more than other premium -grade cassettes.
We think you will find them a bargain.
Yes and no. We have made Volkswagen -style
changes as we have gone along, including the
change of our original meter for better indication
of high frequencies, but the changes were mainly
in the direction of making use of the machine still
easier and more precise. They would be hard to
hear on most musical material, and we made them
mainly because it seemed the responsible thing for
a manufacturer to do.
Why Is The 201 Fairly Small?
Because its design consciously avoids needless
gadgetry that might make it bigger, and also avoids
what you might call "packaging air" in order to
make a product look like there's more in it. We
don't think we have the right to make something
that takes up far more of your living space than it
has to (or whose chrome shines in the dark) to
get you to buy it.
Why Does It Cost Less Than Machines
Claiming Equivalent Performance?
Again, because needless gadgetry is not there. And
because we made the lucky decision to manufacture it in this country, avoiding the price rises that
have resulted on imported products because of the
fluctuation of the dollar vs. foreign currencies.
Why Did We Pick These Questions?
Because every manufacturer attempts to direct
your attention in advertising. We want to direct it
toward the realities that we feel genuinely determine whether something is enjoyable or not,
because what we see on other products including
the confusing variety of super-expensive cassette
-
m
- - ---------mu
1
1
1 Name
I
Address
City
State
-
ow
on
1
1
a-- a---
195 Albany Street, Cambridge, Massachusetts 02139.
www.americanradiohistory.com
AmericanRadioHistory.Com
1
Zip
mu
The Advent 201
Advent Corporation,
I
Advent Corporation,
195 Albany St., Cambridge, Mass. 02139
1
Gentlemen:
1
1 Please send me information on the Advent 201,
along with a list of your dealers.
1
mu gm
_I
Equipment Profiles
Sony STR-7065 AM /FM Stereo Receiver
70
Akai GCX-46D Cassette Recorder
RTR 280DR Loudspeaker System
72
76
Sony Model STR-7065 Stereo FM/AM Receiver
MANUFACTURER'S SPECIFICATIONS
FM SECTION. IHF Sensitivity: 2.0 i_tV. S/N: 70 dB. THD
(Mono): 0.2%; (Stereo) 0.5%. HF Selectivity: 70 dB. Capture
Ratio: 1.0 dB. AM Suppression: 56 dB. Image Rejection:
70 dB. IF Rejection: 100 dB. Spurious Rejection: 90 dB.
1
Frequency Response: 20 Hz to 15 kHz,
dB. Stereo
Separation: Better than 38 dB at 400 Hz. 19 kHz, 38 kHz
Rejection: 40 dB. SCA Suppression: 55 dB.
AM SECTION. IHF Sensitivity: 30 nV (external antenna).
S/N: 50 dB at 50 mV/M. THD: 0.8%. Image Rejection:
50 dB. IF Rejection: 40 dB.
I
Continuous Power Output: 60 watts/
channel, 8 ohm loads, 20Hz-20,000Hz; 70 watts/channel,
at
kHz, 8 ohm loads, both channels driven. Rated THD:
0.2%. Rated IM: 0.2%. IHF Power Bandwidth: 15 Hz -35
kHz. Damping Factor: 50, at 8 ohms. Frequency Response:
dB; MIC: 100 Hz -10 kHz, +0, -3 dB;
Phono: RIAA
High Level Inputs: 10 Hz -70 kHz, +0, -3 dB. Input Sensitivity for Rated Output: Phono, 2 mV, Mic, 1.0 mV; High
Level Inputs, 50 mV. Power Amp Input: .0 V. Hum and
Noise Level: (all referenced to rated input and rated output)
Phono, 72 dB; Mic, 65 dB; high level inputs, 90 dB. Power
Amp Input: 110 dB. Tone Control Range: Bass: - 10 dB
@ 100 Hz; Treble: - 10 dB @ 10 kHz. High Filter: 12
dB/octave above 9 kHz. Low Filter: 12 dB/octave below 50
AMPLIFIER SECTION.
1
1
1
1
Hz.
GENERAL SPECIFICATIONS.
Dimensions:
33'
181/4 in. w. x
lbs. Price:
Power Consumption: 180 watts.
in. h. x 1434 in. d. Weight:
6-3/16
$499.50.
This top -of-the -line stereo receiver from Sony should help to
maintain that company's well-earned reputation for elegance
in design, both internally and visually. The massive gold colored panel, set back and framed by the side panels of the
included walnut finished cabinet makes the STR-7065 eminently suitable for "instant use" on a shelf or table top. Removal of the cabinet discloses a complete metal enclosure
rather than the exposed wiring of the chassis so commonly encountered with competitive units that come "complete with
cabinet." Not only does this feature make sense for those of us
who want to custom -mount a receiver behind a panel in existing furniture, but the extra internal cover provides shielding of
low-level input circuits which might otherwise be subject to
hum induction from other nearby components.
As for the front panel itself, the photo of the complete unit
shows an orderly and carefully thought out arrangement of
controls and switches surrounding a blacked -out dial scale
area which, itself, is over 12 inches long. With power applied
and selector switch set to all but radio functions, subdued green
illumination of the dial area occurs and red program source
indication appears at the upper portion of this area. When FM
is selected, full dial illumination takes place, and both the
signal -strength and center -of -channel tuning meters are
brightly lit. In the AM mode, only the signal strength meter
remains illuminated. At the left of the dial scale, a massive
dual concentric knob/lever combination serves to adjust
volume and balance, while a matching single knob at the
extreme right is used for tuning stations in what is probably
the smoothest flywheel action we have Yet encountered.
Along the lower portion of the panel are a lever-type power
switch, stereo headphone jack, speaker selector switch (as many
as three pairs of speaker systems can be connected to the
STR-7065, with one or two pairs activated at any one time
by this switch), dual concentric friction-loaded bass and treble
controls, filter selector switch, mode switch (with full facilities
for stereo, reverse, L+R, right or left only to both channels),
program source selector and a microphone mixing and level
control, located directly above a piar of microphone input
jacks. In addition, there are lever -type switches for activating
loudness and FM muting circuits and for selecting tape monitoring facilities for two separate tape inputs. In addition to
their normal monitoring use, these tape inputs and outputs
can be used for "dubbing" or printing from one tape recorder
to the other, or vice versa, depending upon the setting of the
program selector switch.
The rear panel, shown in Fig. 1, has the usual provisions for
external program input sources plus the two sets of tape in -tape
out jacks previously referred to. A standard DIN socket
parallels the tape inputs and outputs. Antenna terminals are
provided for either 75 ohm or 300 ohm balanced antenna
connections and there is a terminal for an external AM antenna
as well, should the self-contained pivotable ferrite bar antenna
prove to be inadequate for distant AM signal reception. Pre amp out and main -amp input jacks are also included, which
permit separate use of the preamplifier (to feed other power
amplifiers-as in bi-amp or tri-amp electronic crossover
arrangements) and power amplifier. The usual `jumpers"
are absent from these jacks, since a separate slide switch is
used to "make" or "break" this circuit interruption point. This
thoughtful addition makes the circuit -interruption feature
more useful, since the "preamp out" jacks are available for
feeding programs to other amplifiers even when the amplifier
of the STR-7065 is in use. Normally, the jumpers usually used
to complete such circuits would prevent this additional usage.
Three sets of well -separated speaker terminals, two switched
and one unswitched AC receptacle, and a separate ground
terminal complete the back panel layout.
1
AUDIO
70
www.americanradiohistory.com
AmericanRadioHistory.Com
NOVEMBER
1973
of the internal wiring of the chassis is shown in Fig.
and while at first glance the amount of harness wiring
from module to module seems fairly great, we had no trouble
identifying the various major circuits, which are well labelled
for servicing, if required.
The sealed FM tuner section (front-end) uses junction FET's
in both the r.f. and mixer stages, while the i.f. amplifier section
uses permanently aligned ceramic filters and a high gain IC
for limiting. The AM section has triple tuned ceramic filters
as well, and a single IC circuit which includes an AGC circuit.
The amplifier section uses differential amplifiers and incorporates balanced positive and negative power supplies which
permits direct coupled (output capacitorless) connection to
the speaker terminals. The FM multiplex section includes an
FET for high impedance isolation between the ratio detector
and the input to a single IC stereo decoder circuit.
In all, the STR-7065 contains 5 IC's, 4 FET's, 49 bipolar
transistors and 31 diodes -quite a handful of active devices
for a single package!
A view
2,
Laboratory Measurements
FM performance measurements are shown in Fig.
3.
11
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.
4.q
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C/
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.
'
s
;
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1
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Fig. 2 -Internal chassis view.
IHF
sensitivity measured 2.3 gV, which is not significantly worse
than the 2.0 µV claimed by the manufacturer. Ultimate S/N
reached 70 dB, as claimed, for all input signal strengths above
about 80 V. Mono THD measured 0.18%-a bit better than
the 0.2% claimed, while stereo THD measured just a bit over
the claimed 0.5% at mid-band frequencies. 50 dB S/N was
reached with a signal input of only 2.9 µ V. Muting action was
positive and instantaneous, occurring at a signal input level of
about 8 µV. In view of the excellent quieting characteristics
observed, this parameter might better have been set at about
5 µV and, while no external adjustment is provided for the
customer, potentiometer RT -201, which we located easily on
the included schematic, could be trimmed to readjust the
muting threshold if this is important to the user.
Stereo threshold occurs at an input of 4.5 µV, just exactly
where we felt it should with a receiver of this quality, and the
transition is smooth and positive. Stereo separation, shown in
Fig. 4, reached 38 dB at mid -band, as claimed, falling off to
about 28 dB at 50 Hz and about 20 dB at 10 kHz. Mono THD
was below 0.5% at all frequencies from about 60 Hz to 7 kHz
and barely reached 1.0% at 15 kHz. Stereo THD remained
well below 1.0% from 50 Hz to over 2 kHz, above which
"beats" between the internal 19 kHz and the test frequencies
tended to produce high readings on our distortion analyzer.
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0
10
If the tuner section of the STR-7065 were categorized as
basically meeting its excellent specifications, we'd have to
rate the amplifier as one that exceeds its claims by far. As
shown in Fig. 5, THD reached the manufacturer's rated (and
very low) value of 0.2% at an incredible 85 watts per channel.
Remember, that Sony rates the amplifier at 70 watts mid -band,
per channel and, even more conservatively, at 60 watts/
channel for all frequencies from 20 Hz to 20,000 Hz! At all
power levels below 60 watts, THD measured well below 0.15%,
while IM distortion measured under 0.1% for all power levels
up to 45 watts, rising to the rated 0.2% at 60 watts and remaining at less than 1.0% even at 65 watts per channel and higher.
Even if we consider the nominal output rating of this
receiver to be 70 watts per channel (its mid -band rating),
power bandwidth exceeds manufacturer's claims, extending
from 12 Hz to nearly 60 kHz, as shown in Fig. 6. Distortion
versus frequency for 60 watt and 30 watt levels per channel is
plotted in Fig. 7 and, even at 20 Hz, THD measured less than
0.3% for full power output (60 watts) and well below 0.2%
for 30 watts of output power per channel.
AUDIO
IN
0
ION
FREQUENCY
-NI
Fig. 4 -Separation and distortion characteristics vs.
frequency.
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POWER OUTPUT
60W
100
CYANNEL -WATTS
Fig. 5 -Harmonic and IM distortion characteristics.
NOVEMBER 1973
71
www.americanradiohistory.com
AmericanRadioHistory.Com
range as in Fig. 8. High degrees of attenuation at low, rumble
frequencies and high "record scratch" frequencies become
possible without materially affecting more important "musical"
frequencies-as would be the case if tone controls or less
steep cutting filters were used to correct for such problems.
11 N
7
0dB= 0WATTS
3
-OHM LOADS
BOTH CHANNELS DRIVEN
Additional Measurements
RATED THD = 0.2%
60 pH
10
100
IN
1016
10016
FREQUENCY -H
Fig.
6-Power bandwidth.
Measurements not shown graphically include: capture ratio,
which measured just under 1.0 dB at 1000 µV; FM alternate
channel selectivity, which measured 68 dB at the same signal
input level; AM suppression, which measured 58 dB; and
spurious response rejection, which turned out to be higher
than our 100 dB instrument capability. Kum and noise on
phono (referenced to 3 mV input) read 75 dB-better than
claimed by Sony, while the same parameter measured for the
high level inputs was about 80 dB.
Listening Tests
r
The Sony STR-7065 served as our "listening set" for nearly
ó
a month (we rotate receivers and amplifiers regularly, using
8411
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80TH CHANNELS DRIVEN
0.3
0.2
0.1
3016 CHANNEL
6016 CHANNEL
100
IOK
FREQUENCY -H
7-Distortion
Fig.
vs. frequency.
.15
.10
0
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10
OUONESS CONTOUR,
_
15
-30 SB
FILTER
20
10
100
IN
10K
1006
FREQUENCY-H,
Fig.
8-Tone control, loudness
and filter characteristics.
Tone control, loudness and filter characteristics of the STR7065 are plotted in Fig. 8, and all conform nicely to manufacturer's claims. The use of 12 dB/octave low and high
frequency filters, while requiring a few more component parts
than the more commonly used
6 dB/octave types, clearly
shows up advantageously when plotted against the tone control
them for casual as well as concentrated listening for varying
periods of time, depending upon backlog of sets to be tested).
Largely because of its ease of handling and its excellent control
features, we were unusually reluctant to displace it in favor
of the next set ready to undergo our listening tests. It performed flawlessly during that long period and, a hasty check of
a few FM and power measurements made before we re -packed
it indicated that it was as good as the day we turned it on.
Calibration of the FM band is just about perfect, and there
was no evidence of drift. AM performance was better than
average for our location, and the FM band managed to pull
in fifty-two usuable signals, of which about 28 were stereo
stations. The measured high alternate channel selectivity was
obvious in our listening tests and, with our outdoor antenna
properly oriented, we were able to get a few adjacent channels
(only 200 kHz apart) with listenable quality.
The best thing that can be said about the amplifier section
of the STR-7065 is that like all good amplifier designs, we
were never conscious of its being there-it responded well
at all listening levels, drove high and low efficiency speaker
systems with equal ease and produced all the clean, audio
power demanded by our varied listening situations. The
microphone input feature will find favor with recording
enthusiasts who can use it, instead of going directly into
their tape recorder mic inputs. In this way, tonal deficiencies
of your microphone (or even your voice) can be "sweetened
up" just like the professionals do by simply connecting from
the output of the "preamp out" jacks to the high level input
of your recorder. This trick cannot be accomplished by feeding
from the conventional "tape out" jacks-another virtue of
the unique out -in arrangement provided on the Sony STR7065.
Leonard Feldman
Check No.
71 on
Reader Service Card
AKAI GXC-46D Cassette Recorder
MANUFACTURER'S SPECIFICATIONS:
Frequency Response: 30 to 18 kHz (50 to 15 kHz ±4 dB)
with CCO2; 30 to 16 kHz (50 to 13 kHz ±4 dB) with LN.
Wow and Flutter: less than 0.12%. Signal -to -Noise: Better
than 50 dB; 58 dB with Dolby. Erase: 70 dB. Outputs:
Line, 0.775 V; DIN, 0.4 V; Headphone, 30 mV. Motor:
Hysteresis synchronous outer -rotor type. Dimensions: 16 in.
w. x 111/2 in. d. x 5 in. h. Price: $319.95.
AKAI has long had an enviable reputation for top-quality
open -reel recorders-in fact, they were the first, or one of the
AUDIO
72
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NOVEMBER 1973
What makes the NIKKO 8080 the surprise
sellthrough of the year?
Today's quality-oriented consumer
may not know electronics from a technical point of view. But he does understand quality. And value.
And when you can offer him a
quality AM / FM receiver that combines
both high -end features and a middle range pricetag-you can predict his
response.
The Nikko 8080 offers, among other
things, a feature previously found only
in such high -end components as the
Macintosh C28: a two-tapedeck dub-
,
bing system that gives you two sets of
stereo tapedeck inputs and outputs,
with switching that allows you to dub
from left deck to right, and from right
deck to left. The 8080 also protects
your speakers with a special Nikko designed three -stage circuit breaker.
Furthermore, it is powered by both
a modest pricetag and 45-45 watts of
RMS power at 8 ohms.
The specs, the price, your own ears
and your sales experience can tell you
that the Nikko 8080 is more than just
an exceptional receiver. It is an exceptional sales performer.
So get over to Booth 508 and take
a look at the Nikko 8080, as well as
the rest of the Nikko action -provoking
line, including the Nikko 7070 and the
brilliant top-of -the -line Nikko 9090.
Who knows-with a receiver featuring two-tapedeck dubbing, you
might even be able to sell two
tapedecks!
Think it over.
Two-tapedeck input/output dubbing switching.
VOL UME-+J-BALANCE
ILE
TAPE MON.
1
.001 Lankershim Bk (1, Ao,th Holly,crrod, Ca. 91601
Check No. 37 on Reader Service Card
www.americanradiohistory.com
AmericanRadioHistory.Com
SELECTOR
PHONO 2
AUX.
-,
200 Rte.
I
DUe
IO,
Unit 4, Farmingdale, N.Y. 11735.
0
first, to use cross -field technique. And so it is only natural
that their featured entry in the cassette market would be a high
quality machine using a Dolby system. Model GXC-46D uses
an ADR distortion reduction system, said to eliminate almost
all high frequency distortion above 8 kHz. The styling is
fairly conventional with piano keys for tape control and the
now almost standard slide units for input and output functions.
Reading from left to right, the key switches are as follows:
VU
RECORD, REVERSE, STOP, PLAY, and FAST FORWARD. Next comes
three pushbuttons for PAUSE, EJECT, and power ON-OFF. To the
20
20
IN
100
10N
FREQUENCY -N
Fig. 1-Record-replay
tape.
response with
TDK
KROM-02
üYu
right of the recessed cassette holder are switches for limiter
and tape selector (CrO2 and Low -Noise) and the four slide
controls-two for input level and two for output. At the top
left on an angled panel is the Dolby switch with an indicator
light and at the right are the two VU meters. The microphone
and headphone jacks are located at the front near the AKAI
nameplate and the other input and output connections (including DIN) are all at the rear. Incidentally, the limiter
circuit is described as an "over-level suppressor" and it is
recommended for use when recording from microphones at
close range.
Circuit Details
The circuit of the 46 is fairly straightforward using 39
transistors, 39 diodes and 2 IC's. Figure 6 shows the input
arrangement as it appears in the playback mode. Note that
there is an RC roll-off network as well as an NFB equalizing
loop. Two transistors plus a diode are used in each channel
for the limiter circuit. Bias frequency is 61 kHz and the oscillator is a push-pull type employing an auto -transformer. No
fewer than 16 transistors are used in the Dolby circuit-one
reason for the extra cost involved.
20
100
IR
I0N
FREQUENCY -1z
Fig. 2-Record-replay response with Maxell UD tape.
Measurements
Figure
shows the record -replay response with TDK
KROM-02 tape taken at 0 VU and -20 VU. The 3 dB point
is about 16 kHz. Very similar results were obtained with
Maxell UD Low -Noise tape, as can be seen from Fig. 2. As a
matter of interest, two other tapes were tried-Maxell LN and
TDK ED. The former had a rise of 1.7 dB at 10 kHz with a
3 dB point at 15.5 kHz, the latter having the same 3 dB point,
but with a rise of dB at 10 kHz. The Dolby system was
checked but there were no significant frequency deviations.
Figure 3 shows the response from a standard tape and Fig. 4
1
1
sae
t
20
100
10N
1K
FREQUENCY -1=
Fig.
3-Playback response from standard tape.
3
2
20
100
1K
FREQUENCY
Fig.
5-Distortion
- Hz
vs. frequency.
VU
o
Fig. 4-THD at
the limiter.
2
1
1
kHz. Broken line shows the effect of
AUDIO
74
www.americanradiohistory.com
AmericanRadioHistory.Com
3
NOVEMBER 1973
$1000 worth of electronics can sound like X99.95
if you use the wrong speakers.
AR lets you hear what you've paid
No matter how much you've paid for the
electronics in your stereo system; even if you
have a $1,000 tape deck and a $800 receiver,
if you cut corners on your speakers, you may
as well have bought a $99.95 portable
record player.
Because only AR speakers, priced
from $65 to $600, have the wide, flat
frequency response, minimal
distortion, and high power handling
capacity that can show how good the
A
resi of your stereo or 4 -channel system is.
If you thought it was important to pay the
big dollars for a zillion -watt amplifier with
frequency response from D.C. to ultrasonic. If
you can apprec ate what makes a
tuner worth $500. if you will gladly
pay $100 for a phono cartridge...
you appreciate music-and
technology-enough to insist on AR.
The speakers preferred by
professionals.
TELEDYNE COMPANY
10 AMERICAN DRIVE
for
NORWOOD, MASS. 02062
Check No. 2 on Reeder Service Card
www.americanradiohistory.com
AmericanRadioHistory.Com
15
g'
Rl
Ri
v..W V.n
fl]
C2
M
-I
C3
1--
R1 and Cl
6-Input circuit as switched for playback.
form a passive roll -off network; R2 supplies d.c. stabilizing; and R3, R4, C2, C3 comprise the NFB equalizing
loop.
Fig.
RTR 280 DR Speaker System
MANUFACTURER'S SPECIFICATIONS
Drivers: Four 10 -in. bass, six 2Y2 -in. tweeters. Crossover
Frequency: 3500 Hz. Recommended Amplifier Power:15
to 100 watts RMS per channel. Frequency Response: 22 to
18,500 Hz. Impedance: 8 ohms, nominal. Weight: 95 lbs.
Dimensions: 16'/2 in. W x 39 in. H X 16Y2 in. D. Price:
S299.00
The RTR 280DR is a column speaker which uses a total of
ten transducers. A 10-in. extended range woofer is centrally
mounted on three of the four vertical sides with a 21/2 -in. tweeter above and another below each woofer. On the very bottom
of the free-standing enclosure, a slot -loaded low bass woofer
completes the column and radiates uniformly at floor level.
The fourth vertical side is painted flat black and has terminals
and controls mounted in a recessed cavity. The enclosure is
attractively finished in walnut and black and is definitely a
speaker you would not choose to hide in a corner or out of sight
for either cosmetic or acoustic reasons.
A toggle switch labelled "Normal" and "Bi -amp" is provided
to allow this system to be driven by either one amplifier for
full range sound or a frequency splitting bi -amplification
system. Two sets of binding posts serve as woofer and tweeter
connections when the toggle switch is placed in the Bi -amp
indicates the distortion at 1 kHz up to +3 dB on the VU meter.
The broken line shows the effect of the OLS limiter circuit.
Distortion vs. frequency can be seen in Fig. 5. Output at 0 VU
input was 750 mV with CrO, tape and just under 700 mV with
LN tapes. Input for 0 VU was 45 mV.
Signal-to-noise (unweighted) was 51 dB, increasing to 58
dB with Dolby, which is excellent. Wow and flutter came out
exactly as specified at 0.12% (DIN). Tape speed was just under
1% fast and average rewind time for a C-60 cassette was 57
seconds.
Listening Tests
The GXC-46D was very easy to use: The key switches were
positive without needing excessive pressure and the pause
button worked without fuss. I find it an advantage to have the
pause button positioned away from the bank of piano keys,
as there is less chance of pushing the wrong key when in a
hurry! As can be seen from the graph, the OLS limiter circuit
can reduce overload distortion on high input signals although
it should only be used if absolutely necessary. Summing up:
the AKAI GXC-46D must be numbered among the top halfa -dozen cassette recorders and can be recommended without
reservation.
G. W. T.
Check No. 72 on Reader Service Card
position. In the "Normal" position, the woofer binding posts,
also marked "Normal," serve to drive the complete system. A
tweeter gain potentiometer and a resettable tweeter protective
circuit breaker complete the back controls. In fairness to RTR
engineering, the controls and terminology are well labelled and
reasonably placed, but the purchaser is on his own from the
standpoint of hookup information. A supplementary description
of recommended hookup is something which is needed and we
hope this is a temporary manufacturer's oversight. The use of
good quality insulated terminals is commendable. Connection
can be made without tools using spade lugs, tip jacks, or stripped wire of any reasonable size. This eliminates the fear of
short circuiting poorly connected stranded wire if the speaker
is periodically moved for cleaning purposes.
The lack of hookup instructions together with the choice of
terminal configuration could be an expensive trap for the unwary Bi -amp user. In the "Bi -amp" position the two sets of
terminals are electrically isolated, the woofer and tweeter each
having a black and red terminal, but when the mode switch is
set to "Normal," both black terminals are tied together. If the
amplifiers used for bi -amplification have a common ground,
it is possible to wire the speakers out of phase (such as is commonplace for 12 dB per octave crossovers) and get normal
sound when the speaker is in the "Bi -amp" position. If the
switch is then flipped to "Normal," one of the power amplifiers
will look into a short circuit and possibly be damaged. If this
speaker is used for bi -amplification, we recommend exercise
of caution in hookup.
Technical Measurements
The stated impedance of the 280DR is 8 ohms nominal.
Our measurements indicate that the impedance should be
considered to be slightly above 4 ohms. Figure is the impedance for "Normal" configuration with the two extremes of
tweeter control position. Figure 2 is a plot for the Bi -amp mode
with the tweeter impedance given at the two extremes of adjustment. This speaker should not be paralleled for drive from
most transistor amplifiers. In view of the higher amplifier
demands of this speaker, the heaviest gauge hookup wire
should be used that is practical and consistent with decor.
The anechoic frequency response obtained one meter directly
in front of the speaker is shown in Fig. 3 for the "Normal"
switch position and the tweeter level control set to the mid
position. The amplitude response is - 5 dB from 40 Hz to 14
1
AUDIO
76
www.americanradiohistory.com
AmericanRadioHistory.Com
NOVEMBER 1973
kHz. The response is non -minimum phase only near the
acoustic crossover frequency of 2 kHz. The phase slope indicates the acoustic position of the woofer is about 6 inches
behind the tweeter.
The "Bi -amp" response of woofer and tweeter considered
separately is shown for pressure amplitude only in Fig. 4.
The range of control for the tweeter is +7 dB in the maximum
position to -5dB in the minimum position referenced to the
halfway position of the potentiometer on the rear of the cabinet.
The tweeter control changes the electrical damping causing
some response irregularities below 4 kHz at control positions
less than maximum. If this speaker is connected for bi -amplification, we recommend using the maximum tweeter position
and reducing the gain in the tweeter control of the amplifier.
The frequency response deteriorates off-axis and shows
interference dips at 45° due to an equal contribution of sound
from the identical front and side drivers. Progressing around
to 90°, the response again smooths to a similar form to that of
Fig. 3.
The energy-time plot of the first millisecond of direct sound
for all components from 20 Hz to 20 kHz is shown in Fig. 5.
This is the amount of time spread which an impulsive sound
undergoes when reproduced through the 280DR. Because the
measurement is performed at a distance of one meter in front
of the grille cloth, the first arrival is due to the tweeters and
comes at around 3.2 milliseconds. The impulse response is
within 20 dB of its peak value for 0.25 milliseconds after the
first arrival and within 30 dB for the first millisecond. No
significant energy remains beyond 1.25 milliseconds of first
arrival indicating a desirable lack of internal structure reverberation.
The 280DR is intended for free-standing use in a room. In
order to evaluate the technical performance under these
conditions the speaker was placed on a rug surface in a room
with a hard plaster ceiling slightly over 8 feet above the floor.
The microphone was placed one meter above the floor (slightly
over three feet) and three meters (about nine feet ten inches)
in front of the speaker. An energy -time measurement indicated
that the first 2 milliseconds of sound arrival contained the
majority of direct and floor reflected sound and that the ceiling
contribution was perhaps 5 dB less than the floor reflection and
somewhat less than later scatter arrivals from other portions of
the room. Frequency response measurements were taken for
both the first 2 milliseconds of arrival and the first 6 milliseconds of arrival which would include ceiling reflection.
There was no substantial change in the character of the spectrum for these two time -gated frequency responses. Figures 6
and 7 show the frequency response of the first 6 milliseconds
of arriva for two azimuth positions at 3 meters. The zero degree
curve is the on -axis response and corresponds to sitting directly
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and phase measured one meter on axis with one watt
input.
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Fig. 1-Impedance for normal operation and extreme
position of the tweeter control.
10
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100
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FREQUENCY
Fig. 4-Anechoic pressure amplitude response for the
bi -amp mode with woofer alone and tweeter alone
WAFER
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Fig. 2 Impedance for bi -amp operation using woofer
alone or tweeter alone with extreme positions of tweeter
control.
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Fig. 5-Energy-time response measured one meter on
axis.
NOVEMBER 1973
77
www.americanradiohistory.com
AmericanRadioHistory.Com
in front of the speaker. The second measurement is made for
off -axis position corresponding to the left channel of a
stereo installation with a 60° separation angle. The data is not
continued below 100 Hz because of the six millisecond time
window used for this measurement. A general dip in response
is noted from about 2 kHz to about 7 kHz with a top end
brightness peak in the vicinity of 10 kHz then a drop off above
15 kHz. The tweeter control was placed in the same position
as for the anechoic measurement of Fig. 3. Because of the
a 30°
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Fig. 6-Frequency response for the first six milliseconds
of direct sound including floor and ceiling contributions
measured three meters on axis.
radiation from three sides of the enclosure, the 280DR contributes a substantial amount of room reflected sound in any
normal listening situation. Thus room coloration problems must
be anticipated. The general dip in the treble region is found
at all azimuth radiation angles.
The polar-energy plot is shown in Fig. 8. This is the total
energy in the 20 Hz to 20 kHz range as a function of angle.
The view is that of looking down on the speaker, and this
measurement is made anechoically for the first two milliseconds
of arrival. The plot shows the two extreme positions of the
tweeter control. There is a very clear symmetry of the direct
frontal and side axis as one would expect but .which is not
found near the 45° positions. If these speakers are positioned in a usual stereo configuration such that the front of the
speaker is directly perpendicular to the line of centers joining
them, the polar fingers at 45°, together with the interference prone frequency response at this angle, will give good stereo
localization only over a narrow range of seating positions
when the speakers are farther apart than 60°. The implication
of this polar measurement is that you should rotate the speakers
toward the listening area in order to preserve localization. The
broad dispersion of sound implies that a substantial stereo
effect can be expected due to room reflection.
The 280DR is stated by the manufacturer as being moderately efficient and an amplifier power of 15 watt to 100 watt is
recommended. Our measurements indicate that a one watt
electrical input produces a sound pressure level of 82 dB one
meter on axis at kHz. Even adding the contribution of the
other two major axes, this must rank as a speaker which demands a lot of power. Even if you are not a hard rock enthusiast, you could readily run an amplifier into peak clipping
in a moderately draped listening area if it has less than a 50
watt rating. Our experience in measuring distortion, however,
makes us recommend the use of speaker fuses if a high power
amplifier is used.
The harmonic distortion on the 280DR is extremely low.
A flute tone E, (41.2 Hz) at 20 watts input produced I percent
percent A, (third harmonic). The
E2 (second harmonic) and
critical mid bass remained below 0.4 percent at this same
level. It was not until a power level of 100 watts at 41.2 Hz
that the bass drivers became non-linear as indicated by the
ratio of odd to even harmonic distortion. The sound pressure
level measurement of Fig. 3 is for one of the three equal axes
of radiation. The sound pressure level of 90 dB shown in
Fig. 9 is calculated by adding 5 dB to take into account the
contribution of all speakers in a reverberant environment.
Our undoing occurred during the testing at the 100 watt level.
Even though the tone is applied for about 5 seconds duration
for each component, we managed to burn out one of the
woofers during test. The fault rests solely with us since the
lack of sonic distortion lulled us into testing at high power. The
lesson, however, is clear. Because you need a truly high power
amplifier to get high sound levels, we strongly recommend
fusing the speaker lines with a fast blow fuse rated no larger
than 5 amps. The power level of 100 watts shown on the harmonic distortion plot is that which would be delivered to an
8 ohm resistor. Investigation of the impedance plot shows that
we were in fact delivering close to 200 watts of heating power
to the 280DR at maximum test level.
Intermodulation distortion was determined by using E, and
A, at equal power ratios and measuring the modulation side bands on A,. The relative order of the sidebands indicated that
the effect was more nearly due to frequency modulation than
amplitude modulation. With this type of drive, a 25 watt E,
and a 25 watt A, produce a peak drive that demands the services of a 100 watt rated amplifier. At this level the intermodulation distortion is 2.4 per cent and is composed primarily of
1
Safi
t
10
100
111
FREQUENCY
1
IUS
-Hz
Fig. 7-Frequency response for first six milliseconds of
direct sound including floor and ceiling contributions
measured three meters at 30° off axis.
REAR AXIS
FRONTAL AXIS
Fig.
8-Polar energy plot.
481 Hz, 399 Hz, and 358 Hz. Intermodulation is more prevalent
AUDIO
78
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NOVEMBER 1973
2
01
10
1
POWER
-
WATTS
Fig. 10-Intermodulation distortion using 41 Hz ,lnd
Hz mixed 1:1.
10
B2.
3RD
E2
2ND
E1
A5
-2ND
A4
E4
-
A3
- 2ND
E6
3R0
440
(RCA ARD-1-00l4) was played. Any high frequency tone
control which simply boosts the frequencies above
kHz
would not help this, because extreme high frequencies will
start spitting before the 5 kHz region is raised sufficiently. A
mid -band equalizer would be more effective if your personal
choice is for stronger mid frequencies.
The 280DR has a smooth, solid bass. In moderate size rooms,
the low bass is definitely present but not obtrusive. If you have
any turntable rumble, this speaker will let you know should
you carelessly add bass boost.
This speaker is well suited for the reproduction of massed
orchestral music where absolute pinpoint localization is not
altogether important, though this can be improved by rotating
the speakers toward the listening area. However, the cosmetic
effect of this position for these attractive enclosures leaves
something to be desired. The manufacturer advises that if the
units are to be placed more than 8 or 10 feet apart, a corner
position is to be preferred with rotation towards the center.
Clas-,c organ music, on the other hand, can be reproduced
with great accuracy at high levels. Hard rock music which
to 5 kHz range was not replaces a great demand on the
produced to my complete satisfaction. For example, the Cat
Stevens selection, on Sheffield Vol.II, seemed to lack punch
when played at the levels one usually likes to hear such pieces.
In any event, the best performance can only be obtained from
the RTR 280DR by using amplifiers which are able to drive
50 or more clean watts into 4 ohms.
Overall, the speaker should be considered as very good and
the $299 price tag is quite reasonable for this level of performance. For best reproduction, these speakers need to be used
with high quality components and they may lead you into
buying more than just a pair of speakers.
Richard C. Heyser
1
0
0.01
;00
I
1
1
I
1
80
1
1
1
I
1
1
I
1
1
I
1
1
2
A4
WATTS
SPL
E
-
41.2 Hz
1
SPL
1
A,-11OHz
100
90
80
A
100
90
80
l
11
i
1
3RD
I
1
90
1
1
I
1
1
SPL A4 = 440 Hz
100
,
1
Fig. 9-Harmonic distortion of flute -type tones E. A2,
and A4 as a function of driver power in watts and SPL one
meter on axis.
than harmonic distortion, remaining at nearly 0.5 per cent at
one watt input, corresponding to a quarter watt each of E, and
A..
For the signal suppression test, 440 Hz and 3500 Hz were
used with white noise mixed at an average level 20 dB higher
than the tones. No signal suppression of these equivalent inner
musical voices was noted when the white noise was added,
even up to a noise peak voltage of 80 volts across the speaker
terminals. The 280DR can handle high peak -to -average crescendos up to the capability of the. most powerful amplifier
without compression of inner voices.
Check No. 73 on Reader Service Card
Listening Tests
Several room positions were tried and the most listenable
location was flush against a hard wall and symmetrically located
on either side of a projecting fireplace. Presumably a bookshelf would serve the same acoustic purpose. In other room
locations, the illusion was one of listening to more localized
loudspeakers, though quite good ones. Even in the best wall
position, the sound has good stereo spread but the stereo
localization is not as good, since a phantom center image is not
really well defined and the extreme left and right sound images
are more sharply localized. The flush wall position was found
to help fill in the phantom center channel.
The sound is that of slightly suppressed mid to high frequencies with a modest top end peak which accentuates a few
voice sibilants. The extreme top end which might give instrumental sheen seems down somewhat, particularly when a
disc such as the sparkling Shostakovich Symphony No. 15
AUDIO
Editor's Note
This is the first in a new series of speaker system
reviews. While these test methods are not new, since
they have appeared previously in engineering journals,
they are new to these pages and should generally be
compared only with the reviews following in this series.
A full explanation of the test procedures used begins on
page 20.
NOVEMBER 1973
79
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Advertising Index
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PAGE
75
Acoustic Research
Loudspeakers
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8
68 69
Write Direct to Advertiser
93
Watts Record Care Kit
Empire Scientific
51
Loudspeakers
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.
45
Akai
High Fidelity Components
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60 61
Altec
High Fidelity Components
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100
Applied Physics Labs
APL-9 Speakers
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102
Astatic Corp
Cardioid Mics
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Audio Amateur
104
Audio Construction
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Audioanalyst
94
Loudspeakers
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Audio Dynamics
37
ADC -XT 10 Speaker
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Audionics
95
Loudspeakers
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Audio Research
91
High Fidelity Components
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Audio-technica
12
AT12S Cartridge
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Audio Warehouse
110
Mail Order Discounts
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Avid Corp.
49
Series 100 Speakers
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.
...
99
Turntables
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BGW Systems
10
500R Amplifier
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13,89
Bose Corp.
501 & 901 Series II Speakers
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800 Loudspeaker
Mail Coupon or Write Direct
Bozak
15
Loudspeakers
,
.
,
Epicure
Linear Sound
101
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Fairfax Industries
88
Loudspeakers
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Frazier
104
Loudspeakers
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Harman/ Kardon
67
800+ Receiver
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Harrison Tape Guide
101
.
Current Listings
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Heath Company
1974 Catalog
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KLH Research & Developments
Loudspeakers
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Kenwood
2-4 Channel Receivers
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Lafayette
1974 Catalog
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Linear Design Labs
749A Loudspeaker
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23
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5
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Back Cover
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103
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2
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Logic Newsletter
Sample Copy
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Marantz
Receivers
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McIntosh Labs
Free Catalog
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McKay Dymek
DA3 Antenna
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106
on Reader Service Card
25
on Reader Service Card
99
on Reader Service Card
105
on Reader Service Card
Midwest Hi Fi
109
Mail Order Discounts
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Nikko
73
5010 Receiver
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British Industries
Garrard Turntables
Check No. 17 on Reader
Crown International
DC300A Amplifier
Check No. 18 on Reader
dbx, Inc.
117 Decilinear Expander
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Dathar
Loudspeakers
Check No. 21 on Reader
Dokorder
Model 7100
Check No. 20 on Reader
Elpa Marketing
Write Direct to Advertiser
201 Cassette Deck
BSR
65
47
Thorens Turntables
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Quad Speakers
Check No. 3 on Reader Service Card
.
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Acoustical Mfg.
Advent Corp
ADVERTISER
Dynaco
High Fidelity Components
3
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92
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105
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87
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96
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Onkyo
High Fidelity Components
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PAIA Electronics
Synthesizer Kits
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Phase Linear
High Fidelity Components
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Pickering & Co.
High Fidelity Components
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U.S. Pioneer Electronics
4 -channel Receivers
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.
.
41
.
Service Card
111
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17
ADVERTISER
PAGE
Polk Audio
105
Model 9 Loudspeakers
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RTR Industries
.
.
Loudspeakers
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Radio Shack
STA -150 Stereo Systems
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Revox
Recorders
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Rhoads & Co.
Teledaptor
Check No. 49 on Reader
Robins Industries
Record Protector
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Rogersound Labs
Loudspeakers
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Russound
TMS-1W Selector Switch
Check No. 52 on Reader
62
.
Service Card
43
Service Card
63
106
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12
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6
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89
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Sansui
33
Integrated Amplifiers
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Saxitone Tape Sales
108
Magnetic Tape
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Schwann Record & Tape Guide
Current Listings
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Sherwood
98
39
Loudspeakers
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Shure Brothers
97
Cartridges
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Sony Corp
Sony Sound Lab
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Soundcraftsmen
Frequency Equalizer
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SC-12ES Reflectrostatic
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Southern Sound
Mail Order Discounts
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Superscope
High Fidelity Components
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TDK Electronics
Magnetic Tape
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Ta nd berg
TCD-300 Cassette Deck
Check No. 59 on Reader
Tascam
Mixing Console
Check No. 60 on Reader
Technics by Panasonic
RS-279US Cassette Deck
Check No. 62 on Reader
SA -8000X Receiver
Check No. 64 on Reader
Service Card
11
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58.59
Service Card
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107
Service Card
112, Cover 3
Service Card
56,57
Service Card
35
Service Card
9
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7,29
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19
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Cover 2.1
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United Audio
55
Dual Turntables
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Utah Electronics
16
Loudspeakers
Check No. 66 on Reader Service Card
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Martha Sanders Gilmore
the Kennedy Center on the Potomac has going for
it are its superb acoustics, which
performers and critics alike warmly
praise, though the building has also
been acclaimed for its beauty. The
structure takes shape in a majestic
rectangular slab of white Carrara
marble, some 3700 tons cut to specification and donated by the government
of Italy. The marble is the largest of
the gifts the Center received from
foreign countries. The Kennedy Center
sits on a 17 -acre tract of land, a classic
Greek temple in stark contrast to the
tangled wilderness of Theodore RooseTHE BEST THING
Kert)»e
eteV1m3)
86
AUDIO
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NOVEMBER 1973
and into the future beyond, the Dathar Dà -1 Speaker System
will be far ahead of its time.
Today ...DA -1 stands as a leader, and even with stereo,
quadraphonic and the future "octaphonic' speaker systems, this
Dathar duo -system will produce sound imcging far exceeding that
of omnidirectional and wall -reflecting systems.
DA -1 is the only speaker sy.tem available specifically
developed for multi -channel use.
Listen...to the complete dàpersioi of captivating sound.
Look...at the electronic and mechanical design with
acoustical engineering at its best.
Then
decide...for totally iltegrated sound, the
Dathar DA -1 duo -system
is
for you.
Dealer
inquiries
invited
145 North Franklin Turnpike, Ramsey, New Jersey 07446
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velt Island near the opposite bank of
the Potomac. Architect Edward Durell
Stone said of the site: "It is one of
the most exciting and glorious settings
for a public building in the world."
From atop its expansive roof, the
Jefferson, Lincoln, and Washington
Memorials loom historically in its panoramic view. And underneath its roof
are housed three separate theaters: the
Concert Hall, the Opera House, and the
Eisenhower Theater, separated by a Hall
of Nations and a Hall of States, colorfully blazoned with their respective
flags.
Although ground was broken on
December 2, 1964 for the $68 million
structure, which seats 6500 persons,
construction did not begin until 1966.
A succession of American Presidents had
a hand in its formation. On September
2, 1958, President Eisenhower signed
the National Cultural Act into law.
President Kennedy signed amending
legislation extending the deadline of
fund raising for three years, to give
"full recognition [to] the place of the
artist." After Kennedy's assasination,
The Finer Things /n Life
Jaguar XJ-12-one of the finest cars made today. If you want to buy
one, you have to find a Jaguar dealer. They're not on every corner, as
are some car dealers. But when you want the best, you go out of your
way to obtain it.
Fairfax FX-300-recently tested and top rated by one of the leading
consumer reporting magazines among 20 of the most popular
speaker systems in the $85 to $120 price range. Not every high fidelity
dealer can sell you a Fairfax FX-300 though. You'll have to visit the dealer
we've selected to carry the Fairfax line. But then, isn't the best worth
going out of your way for?
The FX-300 is a two-way, two -speaker system with a ducted port. It
uses a heavy-duty 10 -inch bass driver and a 3 -inch wide -dispersion
tweeter. Frequency response is an honest 24 to 20,000 Hz, and power
capacity is 40 watts rms (7 watts min.) into 8 ohms. The cabinet of selected
walnut veneers-we do our own veneering-measures 22 x 14 x 103/4
inches and is 1 -inch thick on all sides.
If we can build the top rated FX-300 for only $109.95, think of what
our other seven models must sound like from $69.95 to our $399.95 Wall
of Sound I. Visit a Fairfax dealer and let your ears judge for themselves.
To find out which dealer in your area has been chosen to carry the
Fairfax line of speakers, call (201) 485-5400 or write
for a full line catalog; Fairfax Industries, Inc.,
900 Passaic Avenue, East Newark, New Jersey 07029.
the SUPERSOUND line
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FAIRFAX
Made in U.S.A.
88
President Johnson signed into law a bipartisan measure designating the National Cultural Center the only official
memorial in the nation's capital to the
late President Kennedy, renaming it the
John F. Kennedy Center for the Performing Arts.
The person responsible for the remarkable acoustics of the Center is Dr.
Cyril Manton Harris, who holds dual
professorships at Columbia University
while serving as a consultant in the
acoustics field. Harris, a "fireball of
energy" according to his June 17, 1972
profile in The New Yorker, maintains a
rigorous schedule at Columbia, wasting
not a moment's time out of his beautifully organized schedule which is as
firmly packed as canned sardines. Prof.
Harris' regimentation is necessary to
carry out his duties teaching acoustics
in both the School of Architecture,
where he also teaches a course on the
legal and technical aspects of noise
control with Prof. Albert J. Rosenthal,
and the Department of Electrical Engineering and Computer Sciences.
Harris received his doctorate in physics from M.I.T., studying under Prof.
Philip McCord Morse. The author of
numerous scholarly articles in the acoustical field, Harris is editor of The Handbook of Noise Control, published in 1957,
and has compiled a Dictionary of Architecture and Construction, published
this year. Having always been interested
in electronics, Harris is the co -inventor
of a talking typewriter. In view of Dr.
Harris' auditory accomplishments, it may
not surprise you to learn that he has
such exceptionally acute hearing that
he has to wear earplugs to get a good
night's sleep.
Cyril Harris has served' as an acoustical consultant for years and is presently
working as an architectural -acoustics
consultant specializing in large auditoriums. He planned the acoustics for
Powell Hall in St. Louis and we have
him to thank for the acoustic design of
the new 3850 -seat Metropolitan Opera
House at Lincoln Center. It was in this
capacity that he collaborated with
architect Edward Durell Stone in the
design of the three magnificent performing halls at the John F. Kennedy
Center for the Performing Arts in
Washington, D.C.
The Center's first use and grand,
glittering opening in the Opera House
on September 8, 1971 was attended by
members of the Kennedy family and
other carefully coiffed celebrities. They
heard the world premier of Leonard
Bernstein's Mass, commissioned specifically for the occasion-a controversial
work to launch a controversial Center.
The Center's resident orchestra, the
AUDIO
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NOVEMBER 1973
If you've got more than one
National Symphony, conducted by Antal
Dorati, opened the Concert Hall on
September 9th, while the Eisenhower
Theater threw open its doors October
18th with Ibsen's Doll's House, starring
Claire Bloom.
Dance was one of the strongpoints
of the inaugural season of the American
Ballet Theater. The Kennedy Center's
resident company, the Alvin Ailey
Company, and companies came in
from all over the world to dance on the
Opera House's highly praised stage. In
addition, there were 87 concerts by 22
major world orchestras; 46 concerts of
jazz, folk, and rock; a House of Sounds
Jazz Festival and American College
Jazz Festival; 34 recitals by worldfamous individual musicians, and 36
weeks of theater.
The Kennedy Center is young and a
point in its favor is that it has fostered
healthy competition among Washington
area theaters in getting suburbanites
into the city and away from TV. And
despite the vitriol spouted concerning
Center tactics and the occasional caustic
reviews of individual performances, the
commentary on the Center's acoustics
have been virtually free from attack.
Music critic of The New York Times,
Harold C. Schonberg, who attended a
rehearsal before the opening, commented with enthusiasm upon the
orchestral sound of the National Symphony in the nearly empty Concert Hall.
"The sound was reverberant and full,
with a stunning bass quality and unusual
`presence.' The various choirs of the
orchestra stood clearly apart from each
other, but there was a voluptuous mesh.
Indeed, there was no feeling of listening
to music in an empty hall. The sound
was `tight' and echoless, without the
feeling of being in a barn that is experienced at so many rehearsals in unoccupied auditoriums. There even seemed
to be no loss in quality under the
balcony overhangs."
Washington Post music critic Paul
Hume cited the Concert Hall acoustics
as "a modern miracle" and praised the
hall's "clear, balanced, live sound."
Martin Feinstein said exuberantly:
"We have been blessed! We haven't
touched the halls since they've been
opened. Audiences are happy. The
critics are happy, and more important,
the artists are happy. Every artist I
have talked to has raved about the
acoustics in the Concert Hall-Artur
Rubenstein, Isaac Stern, Beverly Sills,
Dorati, Normandy-all praise the acoustics, and they are remarkable. The same
is true in the Opera House. Even for a
straight play. Ingrid Bergman was very
happy with the Opera House in spite of
the fact that it is a big house for a
straight play. The New York City Opera
came down here and they were just
bubbling over about the acoustics in the
Opera House. And the same thing is
true in the Eisenhower Theater. Cyril
Harris has batted 1000, which is unheard of," Feinstein laughed.
There have been, however, a few
minor grievances by some performers
concerning the difficulty of hearing
onstage, especially in fortissimo sections,
and another Washington Post critic, Alan
Kriegsman, insists the Concert Hall
doesn't live up to "its paradigm in
Boston." Paul Hume recently commented on the audible transmission of
coughs and whispers and those Concert
Hall doors which close with a bit of a
bang when people simply must get up
during a performance. (The doors
reportedly have been since worked
on.) This writer has noted a certain
shrillness in sound quality as though the
hall is almost too sensitive. Noticeable
also is a tendency for the percussion
instruments-except for the piano-to
override and sonically smother their
fellow instruments so that (at jazz concerts in particular) it is often necessary
to place a pad or shield in close proximity to the drums.
But, for the most part, these are
minor flaws, and there is talk of recording in the Center's halls for all
their clear, lively, well-balanced sound.
Dr. Cyril Harris summarized: "It came
out exactly as we planned it."
Harris actually began work on the
project as early as 1965 in close consultation with the architect and engineers,
thereby getting the jump on problems
and preventing them by superimposing
acoustical principles upon Stone's
design from the very outset. Harris
says: "Acoustics is a science. Applied
acoustics is both science and art-the
application of experience to the science . .
Dr. Harris encountered very special
problems in the acoustical design of a
Center for the Performing Arts beset
by the traffic noise of a neighboring
parkway and in the direct flight path
down the Potomac River of low -flying
jets coming in for a landing at nearby
National Airport, directly downstream
from the Kennedy Center. Helicopters
at times hover about the Center like
gigantic mechanical bumblebees. Harris
notes the Center "posed some unusual
and severe problems in acoustical design
because of exceedingly high peaks in
the background noise level." It was
therefore crucial to insulate the Center
from all extraneous noise sources.
Dr. Harris describes the Center's
construction as a "box -within-a -box"
wherein the three auditoriums are
tape recorder, you need a Russound TMS-1W
Tape Recorder Selector Switch
Use as many as three stereo recorders with your
audio system for tape duplicating, editing, sound
effects, taping off the air, etc.
Record,
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and monitor in any
Elimicombination.
messy
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Increase
changing
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$32.95
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Russound/FMP, Inc.
Portsmouth Avenue Traffic Circle
Stratham, New Hampshire 03885
If you've got more than one
set of stereo speakers and one
or two amplifiers, you need a
Russound MP -2 stereo control center
Handles up to four pairs of speakers and two receivers or amplifiers Provides amplifier selection
and volume control for each pair of speakers Uses
low loss stereo
"L" pad controls
Eliminates am-
plifier overload
with any combination of 8 or 16
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Designed for 2 or 4
channel home and commercial music systems, pag$74.95
ing systems, etc.
Made in USA. If not available from your audio
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GOOD SHOULD A
REINFORCEMENT SYSTEM
SO GOOD YOU
SOUND?
DON'T HEAR IT!
HOW
Listen
to
NOVEMBER 1973
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the
remarkable
-ffosFBoo Portable Loudspeaker System
the
is
and all you'll hear
performance, without artificial
After all, isn't
coloration.
the performance really what
the audience comes to hear?
Bose 800, The Unobtrusive One
Please send complete
information to:
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ile
P
J
insulated from noise by individual
level of no higher than NC -20 was insupporting columns completely indesured throughout the stages and audipendent of the columns supporting the
toriums, and all transformers and meouter framework of the Center. This
chanical units were strategically placed
tatic also protects the theaters from
to the advantage of noise control. Cyril
noise of facilities such as kitchens and
Harris lists other noise -control measures
cafeterias directly over them. In most
as "
specifications which limited
cases, Harris implemented solid 6 -in.
the noise output of potentially objectionhigh -density concrete block double al noise sources, and the appropriate
walls separated by a 2 -in. airspace filled
use of floating slab constructions, inertia
with low-density fiberglass laid on
blocks, resilient mounts, flexible conload -bearing cork, and used sound nectors, duct lining, damping materials,
rated doors. In each instance, noise and sound traps, as required. Where
rated doors are used for auditorium
noise from piping was a potential probentrances and each auditorium is enlem, flexible connectors and resilient
closed by corridors at each audience
hangers were used. Finally, where space
level to prevent noise from pedestrian
requirements were such that it was
traffic in and out of it. Described as
necessary to locate a quiet area under
"sound locks," the theaters have acousa mechanical equipment room, a retically treated ceilings, their walls are
siliently hung ceiling was used in that
covered with 2 -in. thick absorptive
quiet area."
acoustical board faced with carpeting,
The Concert Hall, the largest of the
and their floors are covered with carCenter's auditoriums seating 2,759
peting.
persons, ìs a rectangle and is similar in
Separating each of the auditoriums are
shape to some of the finest concert halls
the Hall of Nations and the Hall of
in the world such as the Concertgebouw
States, two enormous halls through
in Amsterdam, the Musikvereinsaal in
which ticket -holders pass to reach the
Vienna, and Boston's own Symphony
individual theaters. Forty feet wide and
Hall. Because of the decorative embel63 feet high, the halls run all the way
lishments of gargoyles and cherubs,
from the front of the auditoriums to
indicative of the time when these halls
backstage. At intermission, theaterwere built, they provide excellent
goers gather in an additional hall of
acoustical diffusion. A problem at the
gargantuan proportions, the Grand
Kennedy Center was to achieve a perFoyer, one of the largest rooms in the
suasive acoustical design compatible
world. An awe-inspiring promenade 600
with the architectural concepts of Mr.
feet long, 40 feet wide and 63 feet
Stone, that would perform the same
high, the Grand Foyer flows down the
function. In keeping with the period,
entire length of the Center in front of
Harris used no clouds or other modern
the three auditoriums with its west side
devices.
flanking the river. Along the west wall
Splayed wood panels, 3/a -in. thick and
is the 7 -ft., 3000 lb. monumental bronze
extending from ceiling to floor along
head of the late President Kennedy
the side walls are one such element of
sculpted by Robert Berks. The Grand
diffusion. Projecting about 30 in. from
Foyer creates another potential noise
the wall surface, they provide ample
problem in that the audience from one
diffusion at low frequencies. To facilperformance often stands around in it
itate diffusion at higher frequencies,
chatting while another theater is in
Harris used a lapstrake construction in
operation. Air traffic noise is also a
fabricating the splays whereby each
hazard in the Grand Foyer. Therefore
vertical wood board overlaps the one
special sound considerations were
adjacent to it so that varying widths are
required such as carpet on the floor
exposed. The panels are attached to a
underlayment, acoustical plaster on the
solid wall 6 -in. thick with about a -in.
ceiling, and a total of 40 sound -absorpairspace filled with a fiberglass blanket.
tive panels on the walls. The side of the
A solid plaster wall surface 3 ft., 11 in.
Grand Foyer overlooking the Potomac
wide separates each of the panels into
is glazed and large acoustic double which are set the side entrance doors
window units seal out air traffic noise
to the hall, intentionally recessed 6 in.
as well as providing thermal insulation.
from the edges of the side wall splays
Both panes of glass in each unit are
to create additional diffusion.
"mounted with a resilient seal so that
Harris prefers his ceilings to be thorthere is no solid connection between the
oughly broken up. The 52 -ft. high
glass and the surrounding frame."
ceiling of the Concert Hall is coffered
The noise from the air-conditioning
and comprised of a multiplicity of
system was a factor in Harris' overall
hexagons about ft. in depth. Set within
acoustical plan and by consulting with
them are stepped hexagonal surfaces
architect Stone and the engineers in the
of varying sizes centered around a
early stages of construction, a noise
small perforated metal hexagonal sur.
.
.
,
1
1
90
face. Some are diffusers of the airconditioning system, others are backed
with solid plaster to prevent unnecessary
acoustical absorption. Moreover, some
292 spherical balls intervene to further
diffuse the sound and are interspersed
throughout the ceiling for diffusion at
high frequencies together with 11 large
crystal chandeliers given by the government of Norway. Because of their
unique tier design, the chandeliers diffuse the sound in several frequency
ranges. To prevent bass frequencies
from being soaked up, the ceiling is
extremely heavy. A concrete plank
above it insulates the Concert Hall
from the kitchen and restaurant facilities overhead.
A very shallow balcony overhang
obviates a reduction in sound level
underneath it. A series of 1 -in. thick
plaster panels on metal lath comprise
the balcony facias. Arranged in groups
of three, they form splayed surfaces to
contribute to sound diffusion.
The hardwood floor consists of red
oak on the stage floor and white oak
nailed on plywood in the seating areas.
Harris explained: "Wooden floors cost
more, but you know how it is in a great
hall. You can literally feel the music
through your feet." Identical chairs are
used in the three auditoriums, carefully
scrutinized and chosen for their acoustical properties by Dr. Harris. A minimum of carpeting covers the aisles and
crossover at the rear of the hall. In
order to select carpeting which possessed
the desired sound absorptive characteristics, Harris utilized an impedance tube
measurement technique, choosing the
carpet "on the basis of its sound absorption versus frequency characteristics,
being lower than the other samples
tested at high frequencies." After carrying out comprehensive comparitive
tests of various carpets in his laboratory,
Harris chose a 70% wool, 30% nylon
carpet with a cut pile of about 0.16 in.
in height laid on concrete for all the
theaters in contrast with the carpet in
the exterior foyers where high sound
absorption is a prime requisite.
The Concert Hall stage is surrounded
by splayed surfaces similar to those on
the side walls but varying slightly in
dimension, thereby making it possible
for the players onstage to better hear
one another. The over 4,000 pipes of an
Aeolian -Skinner organ dominate the
upper rear of the stage but can be closed
off from view.
The Kennedy Center's borsch-red
Opera House is the central theater and
the most attractive of the three, playing
host to musical comedy and ballet as
well as to grand opera for which it was
primarily intended. With a seating
AUDIO
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NOVEMBER 1973
capacity of 2,319, the Opera House is in
the shape of a horseshoe and it was the
intention of architect Edward Durell
Stone to achieve as much intimacy as
possible for both performers and audience. This was accomplished. There is
absolutely no bad seat in the entire
house. Sightlines to one of the largest
stages in the world-the space behind
the curtain surpasses the auditorium
itself-are uniformly excellent.
Adjoining convex-shaped cylindrical
surfaces form the rear and side walls
of the Opera House, separated one from
the other by ornamental recesses. On
the sides, these convex surfaces are
constructed of -in. plaster on metal lath
backed by 6 -in. solid block which follows
the convex shape. A -in. airspace lies
between the plaster and the block. The
rear walls are of a similar design but
are constructed of preformed curved
3/4 -in.
wood paneling fixed to solid
block. A fiberglass blanket is inserted
into the intervening -in. airspace.
The center of the Opera House's
ceiling is recessed and is of a 27 -ft.
radius broken up by 4 stepped surfaces
tilted convexly downward. Mounted
therein is a splendid starburst crystal
chandelier given by the government of
Austria which diffuses the sound at
high frequencies. Convex diffusing
surfaces radiate outward from the
1
1
1
center of the ceiling, widening as they
reach the outer edge. It is composed of
plaster on metal lath and is of a minimum thickness of in.
On the facias of the box tiers, curved
panels bowed outward diffuse the sound
waves and are formed of 3/4-in. plaster
on metal lath. The floor, which slopes
about 7 degrees, is fully covered with
a low -pile carpeting laid on concrete.
Because the hall is to be used for speaking as well as singing, a lower reverberation time was required than for traditional grand opera.
The Eisenhower Theater for drama
seats 1,142 persons and is the smallest
of the three completed theaters. Contiguous triangular splays which extend
from floor to ceiling form the rear and
side walls and are made of 3/4 -in. East
Indian Laurel veneer panels mounted
on 6-in. solid -block walls. Again fiberglass fills a 1 -in. intervening airspace.
Each splay projects about 18 ins. into
the theater and each side of the triangular splays is approximately nine
feet in width.
A box tier and balcony have facias
consisting of a series of vertical bars.
Lighting units for the stage lie behind
the grill and behind these lighting units
are fiberglass blankets. The soffits of
the tiers are formed of -in. plaster on
metal lath.
1
1
The ceiling is spanned by convex shaped surfaces from one wall to the
other. It is resiliently hung from the slab
overhead and is of I -in. plaster on
metal lath. The floor, which slopes about
8 degrees, is fully carpeted with the
same carpet that is used in the Concert
Hall. It is interesting to note that in the
2h full theater Sargent Shriver fired a
small cannon whose decay was recorded and analyzed by Dr. Harris two
days before the official opening of the
Eisenhower Theater.
I have attempted here to sketch out
the tremendously detailed and complex
acoustical plan Dr. Cyril Harris implemented in the Kennedy Center for the
Performing Arts. In preparing this nontechnical blow-by-blow description, I
am deeply grateful to the mastermind
himself, Dr. Cyril Harris, who kindly
permitted me to use his article "Acoustical Design of the John F. Kennedy
Center for the Performing Arts" which
appeared in the Journal Of The Acoustical Society Of America, Vol. 51, Number 4 (Part 1) 1972. It is thoroughly
informative and readable and is absolutely indispensable to this piece.
Readers who are interested in additional
statistics such as reverberation time
charts, tables, and architectural plans
would enjoy reading his article in its
entirety.
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ETC
Edward Tatnall Canby
opera house effect
more wearing upon the psyche
than what I like to call the
Wagnerian hush. It comes somewhere
in the middle of one of those vast
five-hour music dramas and you must
be there to appreciate it. After hours
of massed togetherness in the dark,
crowded house, there comes a long
decrescendo. The music goes down and
down, until time and sound are suspended and only a thread of continuity,
a few faint notes, breaks into the long,
pregnant pauses. Nobody breathes. It's
awful. Don't think that John Cage
discovered the musical silence.
Of course, these moments are but
the distant prelude to some vast sonic
climax, a veritable Krakatoa of music,
which will arrive, say, an hour and a
half later. It's all calculated-a stupendous dynamic range-and Wagner
spreads it out over unthinkable lengths.
He knows exactly where he is going,
though. And you will go with him
whether you want to or no. Many an
opera fan, overwhelmed, goes soundly
asleep. It's an easy way out-you might
think. Not a bit. Hours later, you wake
up with a violent start, your hair
absolutely on end. You've heard every
note and you're just in time to be
flattened by the monster climax. Asleep
or awake, you can't resist, and no use
trying. That is, in the opera house.
On records, Wagner is a problem.
Just try the Wagnerian hush in your
living room. Down goes the volume,
lower and lower, right on schedule,
say, the beginning of side 7. Slower and
slower. Long pauses. Churn, churn,
churn! That's your turntable, relentlessly
pulsing its 331/2. Ssssr, ssssr. Tiny residue
of tape hiss after Dolby, brutally exposed. Then BEEP! BLAAST! Your
neighbor cuts in with his auto horn. It's
in the wrong key. A roaring crescendo
of drums? Nope, just a hopped up
Pontiac out on the street. Faint shrieks
of agony-Brünnhilde immolated? The
kids outdoors, playing gangster. Kerplunk. The refrig went off. Throb,
throb. The air conditioner or, maybe,
the furnace, according to season. And
at this moment, of course, the phone
THERE IS NO
rings.
Meanwhile, back in the opera, a
French horn gives a faint burp, once
twice. Or was that a distant diesel
locomotive? Not easy to tell. Poor
Wagner! A thousand petty distractions,
all reeking of now, hopelessly entangle
his calculated silences in the rapid-fire
sounds of our own age. A wholly
different time sense. It's a problem
...
92
common to much classical recording
but never more dramatic-or nondramatic-than in Wagner, whose musical pace is that of the eons, glacierlike, inevitable, and who demands and
gets total, attention. Again, in the opera
house. Where else? That was all he
knew.
So why do we have whole albums of
Wagner on LP? Pure human cussedness.
And imagination. If we really want to,
we can wrench ourselves back into that
atmosphere and hear the slow silences,
in spite of interference. And our recording engineers, too, can do vital things to
aid the musical translation we must
have in order to remove Wagner from
opera house to living room. That's
recording technique. Its specialty is
not being literal.
With all this as background, you will
marvel with me at the bravado of
Philips. This big Dutch record company
has been recording whole Wagner
operas, one after the other, right in the
opera house at live performances.
Crazy. We need every bit of flexibility
that modern recording technique can
devise if we are to make a workable
Wagner translation and to do such an
enormous, risky, expensive job other
than via the recording session would
seem corporate suicide. In most other
Wagner recordings of recent times, the
live productions are followed by
separate sessions for the recording. In
Wagner, these enterprises are almost
beyond belief. The entire production,
refashioned for the recorded result, is
laid out in some vast hall, the artists
spread everywhere, on the floor, in the
balconies, backstage, surrounded by
seas of cable, hundreds of pieces of
equipment; alternative takes are taken
ad infinitum, until each segment is
precisely right. The continuity is as
likely to start with the final scene and
end with the overture as the other way
around. A vast and complex ingenuity
(and more and more like film production), all in the service of musical
translation. From the live opera to the
recorded opera! Every bit is justified,
as we hear the Wagnerian drama unfold at home in a situation totally inconceivable to Wagner himself.
I am trying valiantly, you see, to tip
you off on the momentousness of
Philips' achievement in taking down
Wagner whole and live from the stage
performance-and making it work, right
in the original Bayreuth opera house
that Wagner himself built a century
ago for his own music. Well, you
AUDIO
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NOVEMBER 1973
mutter again, isn't that a literal hi-fi
reproduction, if ever there was one?
The horse's mouth! Nope. It is still a
translation. Philips is successful because
they take this for granted, even though
the live and the recorded versions are
the very same performance.
What Philips has in mind is to capture as much as possible of the human
quality of a living performance, before
an audience on a stage, while providing
those necessary adjustments, via recording technique, which make the
translation acceptable in living room
terms. That's a tall order, though they
had a lot going for them in the special
circumstances of the Bayreuth Festival.
So many things can go wrong in a live
recording. No corrections-a mistake
hysterical, full of nerves, uneven, and
often unbelievably replete with glaring
mistakes, wholly unnoticed in the
glory of the actual occasion. When you
chop off half the circuit and toss the
result, like a leg off the musical body.
out into the living room, you are
changing the entire musical substanceit is no longer the same performance.
A recorded live performance, then..
must be extraordinarily well controlled..
perhaps even to the point of non -incandescence. The Philips Wagner is
precisely that. Yes, one does sense the
audience, indirectly, though it remains
astonishingly silent. But the singers
have that audience before them, and
the strength and purpose can be heard
in the music, ever so clearly. But there
are no nerves-almost none. All is
discipline, a maximum energy transfer
into pure musical expression.
Whether these performances "took
off- in the actual opera house. I could
not say. I wasn't there. That is another
matter altogether-a different performance, if you will.
If the audience is supernaturally
quiet, what of the opera staging and
the acoustics, as we hear them? I'll
have to take my hat off to Philips'
seasoned wisdom in this area. They
mistake-unthinkable in a recording that is to be heard again and again.
is a
limited possibility for joining parts
of live performances-they seldom
A
match. The mood is different. The
weather changes, and the humidity.
Even the pitch. So do stage movements, and hence mic balance. Singers
sing louder one night than on another.
The embattled engineers can't do a
thing; they must take what comes. A
ghastly risk.
Miraculously, little of all this shows
up in Philips' astonishingly smooth and
natural productions. Mistakes? Virtually none. Very few of those minor
mishaps, that usually abound in live
recordings. One must assume that these
seasoned productions were done over
and over again and honed to razor
precision. Bayreuth runs a heavy
schedule and is the mother -house for
the entire living Wagner tradition. Its
singers, top pros, are unlikely to fall
into states of nerves in the face of a
"simulcast" for the live audience out
in front and for posterity via the mics.
The conductor of the new "Ring"
series, all twenty -odd hours of it, is
Karl Böhm, another veteran pro who
keeps things in hand down to the last
detail. One might-if one were Philips
-take a risk on these people. One did.
What of the effect of the live audience? Musically, it should enhance
the impact of the singers. The excitement of such a performance is a twoway thing, a vibrant emotional circuit
between performers and around audience. That is what we miss in many
dramatic recordings done without an
audience. Can't be helped, and we do
get fine music even so. But-if we
could translate the audience feel,
without the audience disadvantage
(most of them are noisy). it would
he fine.
Can we? Too often an exciting live
performance makes an anticlimactic
recording, even when the audience
behaves itself acoustically. Tense.
AUDIO
NOVEMBER 1973
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understand, even the Wagnerian hush.
They make a recording that works as
a recording, a true translation of the
musical intent. It isn't at all what you
hear from the audience.
What Philips does is, of course, to
put us on the stage itself, not in the
audience. So that we perceive everything in carefully exaggerated close-up
impact, to carry us through in the
tough living-room situation. The singers
are no more than a dozen feet away,
right before us. Every note, in the dry,
warm acoustics of the house itself,
is ultra-clear, every syllable precise.
The big orchestra is spread out behind
the singers, not in front and below, as
it is heard by the audience, but in a
wide stereo spread-much wider, again,
than the spread heard from that fabled
"best seat in the house." The acoustics
are indeed dry, as in most proper
opera houses. But not lifeless. Far from
it. I have seldom heard strings so realistically projected in recording. Topnotch mic placement.
I will admit that there are some
debits. All is well when the gods and
heroes and heroines are doing their
long tête -á-têtes, musical conversations
person to person. Or when one of them
launches into a half hour synopsis of
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previous events. (The "Ring" cycle is
well known for its endless catching up
on what has happened before, and
before that.) Here, the close-up vividness of the singing makes it easy to
follow the dramatic sense, especially
with the aid of the complete text and
translation. You begin to understand
that these long passages aren't really
so bad. One up on most opera goers!
They have to guess, if their German
isn't so good.
But Wagner's characters are curiously
contradictory, half god, half man, at
one moment fallible and human, at
another suddenly rearing forth as
symbolic figures of timeless dimension.
When this happens, it is not comfortable, nor right, to be so close. Bad
to feel the angry Wotan's every breath,
hear his teeth click. Wagner meant
these great people to stand off at a
distance in a stage world of their own
and that is how they are heard in the
opera house.
Luckily, the Wagner orchestra rescues us. Always the direct protagonist
of the voice, it rushes in to cover the
too -closeness whenever the great climaxes come along. Philips knows better
than to play it down in the balance.
The orchestral stereo is fully enveloping and beautifully projected. So the
climaxes are climactic, and you'll
love 'em.
If I were to make hours of AB tests,
I think I'd favor by a small hair the
Philips competition, made by the
other system. Notably the Von Karajan
recordings for Angel and Deutsche
Grammophon. They project a smoother,
more
even
dramatic
continuity.
Greater control of the ultimate sound
is the answer-via the specially set
up recording session. (And what a
paradox, that these recordings are put
together in bits and pieces!) Von
Karajan himself has a lot to do with
it, an expertly dramatic conductor and
a man who knows recording and respects it.
The Philips live -recorded Wagner
is inevitably a bit uneven. Remarkable
that it is not worse. At times we seem
to lose contact with that stage production and the music drags. (But was
the live audience impatient? An interesting question.) I do love the warm,
dry Philips sound, Wagner's own
acoustic. But, on records, I found Von
Karajan's big "concert hall liveness"
thrilling, even though like no opera
house in existence. Why should it be?
This is a recording.
So take your choice. But don't ever
think that a live recording is a literal
reproduction of any original. Not even
a simultaneous and identical one. It
is still a recording. for better or worse,
and that's how it sinks or swims.
AUDIO
NOVEMBER 1973
Introducing the
TL -90
Sherwood's Forest
Sherwood L. Weingarten
'M GETTING remarried! Maybe it's
Ijust November, with its biting
wind, that lashes at our illusions
and makes us confront reality. Perhaps
there's enough stamina left to whip the
fatigue, the enormous weight of time,
that buries dreams.
Over four years ago, I wedded myself
to this column, which promised its
own brand of love, experimentation,
vitality. The column was faithful; I
cheated. Somewhere along the line, I
traded romance for traditionalism,
wandered from imagination to dullness.
Worst of all, I let myself become boredjaded by listening to, and commenting
on, too many recordings marketed by
money-managers instead of musicians.
So I wrote about things others found
interesting, eating up valuable space
with bland commentary or playful puns.
No more. I've declared my independence, which enables me to return to
the starting point, the wedding point;
only the original, the fresh, the exciting
will gain my ear. And if that leaves out
Mantovani or Donny Osmond or a host
of others, so be it.
To commemorate the event, sort of
a second time, let's begin with a ceremonial cliche-something old, something
new, something borrowed, something
blue.
The old is THE BEST OF MARLENE DIETRICH (Columbia, C 32245).
Dietrich is an original, one -of -a-kind
creature abhorred by advocates of Women's Lib. Her nasal, tremble -filled
voice offers sultry sex in a manner that
will bemuse and interest as long as
chemistry between genders exists.
Charm seeps from the LP, which is
introduced by Noel Coward-another
unique show biz dinosaur-via clever
drawing room verse. But the show
belongs to Dietrich, whether she's
stealing from Fats Waller (Honeysuckle Rose) or Edith Piaf (La Vie En
Rose) or Cole Porter (The Laziest Gal
in Town).
Style, some would term it; others
would label it class. Either way, it's the
kind of thing that makes each listener
feel as if she's singing just for him.
Falling in Love Again, for instance,
is a tour de force created from a song
whose limits ordinarily are all too
obvious; The Boys in the Backroom
can't be done effectively by anyone else;
I Wish You Love must increase the rate
of your heartbeat, and Lili Marlene is
proof that memory can be pure.
Old in years, yes. But these reissues
are as perfect now as the refurbished
Pieta.
Stepping from the past to the future,
we find a new LP from a young performer destined for superstardom,
MICHAEL FRANKS (Brut, 6005).
He's funky, poetic and incredibly
honest.
The genre is folk-rock, a good deal
of it vastly softer than the heavy metal
sound that's regaining popularity, but
even buffs of the latter will pay homage
to Franks' talent if they give him
a chance. His melodies tend to be
simple, though it's evident he's done
his homework in jazz and the classics;
his lyrics are poignant, lovely excursions into a stream of emotionalism.
As for his voice, it carries enough
impact to enable him to compete with
the likes of Carole King, Roberta
Flack-or even latter-day Dylan.
It would be criminal, furthermore,
to fail to mention his instrumental
abilities: acoustic guitar, banjo, and
mandolin almost seem as if they were
created for him to use as an aid to
his music.
Best of the ten cuts on the LP, distributed by Buddah, is Three Today,
a masterwork that sharply contrasts-in
words and melody-the disillusionments
of adult life with the innocent joys of
childhood. Additionally, it pinpoints
how parents can gain new insights and
hope through the actions of their
offspring.
Little Sparrow, another joy, is a
paean to life and love and natural
wonders, contrasting frailties and
strengths. And Can't Seem to Shake
This Rock and Roll, which is getting
heavy airplay, alludes to the classics
and jazz and is a personal statement
of where the artist is at.
The album favorably compares
with two others from a couple of years
back, one the debut of a Pete Segger
disciple, Don MacLean, the other the
first LP by a virtually unknown song smith, Carole King,
The TL -90 by Audionics* incorpo-
rates
a full complement of
RADFORD components with
transmission line bass loading.
The TL -90 is one of four high performance transmission loudspeakers from Audionics. Write
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95
NOVEMBER 1973
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City
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Segment three of our ceremonial
offering consists of THE NAKED APE
(Playboy, PB 125), an original soundtrack LP from a film "borrowed"
from the Desmond Morris book of the
same name. Spotted with both sardonic
humor and serious historical perspective, the vinyl is one of those rare
examples of a recording that whets
your appetitie and makes you want
to see the movie.
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The score is by Jimmy Webb and
includes four new vocals (which he
sings), in addition to satirical version
of You Brought a New Kind of Love
to Me, a gospel-screecher (Jesus Loves
Me) and an excerpt from a Bach classic.
Naked Ape Theme (Fingerpainting)
is one of the Webb creations, an excel-
lent, moody piece that probably will
win an Oscar if a superstar does a
cover version. But the best moments are
found on Survival Rag, a funny but
biting tune sung by director-screenwriter Donald Driver.
It's the kind of album that surprises
because it truly entertains-and lets you
think as well, if you choose.
Finally, something blue is available
on Mercury's NO MORE, NO LESS
(SRM 1-666), with a dozen tracks
taped by an exciting quartet, Blue Ash.
Most of the music is original, with
nine of the songs penned by Frank
Secich, bass guitarist for the group,
and Bill "Cupid" Bartolin, lead guitarist; a tenth was written by Jim Kendzor,
Blue Ash's lead vocalist and rhythm
guitarist.
Although there is some repetition,
there's enough hard rock variety to
keep any fan happy. Witness, for
example, Just Another Game, a superlative, multi-tempoed view of life
today, slapping at those who do what
they think is necessary when it really
isn't; Smash My Guitar, a fascinating
look at emotions, particularly those of
a rock performer; All I Want, good
old-fashioned rock 'n' roll, and Wasting
My Time, which has won a large
amount of DeeJay favor.
Each of the musicians has passages
that merit raves (including drummer
David Evans, the only group member
not credited with songwriting skills).
And together they can do novel wonders with hackneyed things such as
Bob Dylan's Dusty Old Fairgrounds
or a Lennon -McCartney clinker Anytime at All.
Blue Ash does its damnedest to chase
away the blues; it succeeds.
ty, Calif. 90230
RICHARD NIXON: A FANTASY
(Buddah, 1600) finds David Frye satirizing the President's plights with
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AUDIO
NOVEMBER 1973
Watergate, taking the Man From
Whittier from involvement with the
bugging incident to incarceration in
Folsom Prison and his subsequent
execution. Frye, the foremost mimic
of Nixon's voice, slightly exaggerates
Tricky Dicky's woes. As when Nixon Frye talks to the American people
shortly after learning of the magnitude
of the scandal. Says he: "Today I have
regretfully been forced to accept the
resignation of 1,541 of the finest public
servants it has been my privilege to
know." No matter which side of the
political fence you're on, listen-and
laugh.
THOMAS
CLAYTON
DAVID
(RCA, APL 1-0173), former lead singer
of Blood, Sweat & Tears, goes it alone,
sort of. He's actually backed by a
group even bigger than B,S & T-but
he's billed as a single now. His "debut"
LP, which combines rock, blues and
country, ranges from great (LennonMcCartney's Can't Buy Me Love)
to good (Hoyt Axton's Sweet Fantasy,
despite the slick, gimmicky arrangement) to horrible (Hernando's Hideaway). Mostly, though, he's a man with
star quality-particularly when his
voice is in counterpoint with the brass
section. Alimony could be a sleeper hit,
country -rock at its best. Thomas should
stick to singing, though; the three
tunes he penned are only mediocre.
BECK-BOGERT-APPICE (Columbia, EQ 32140) is one of the best
quadraphonic discs so far, the nearly
perfect vehicle to envelop you in sound.
It's fashionable for critics to knock
supergroups (like the late, lamented
Blind Faith), usually commenting on
the difficulties of ego clashes, and the
pattern has been continued in some
rock journals with B -B -A; problem is
that the group deserves better treatment, for this recording will be played
long after its components have split.
Best of the nine cut are Black Cat
Moan, a heavy, heavy sound; Stevie
Wonder's Superstitious, replete with
tribal rhythms, and Don Nix's Sweet
Sweet Surrender.
RAINBOW (MCA, 2103) resembles
that it anthologizes
Neil Diamond hits, 11 of them. The
difference here is that no original
Diamond creations are present; all the
tunes were written by others. Nonetheless, for those who enjoy the singer's
folky style, this could bd a real money saver. The lineup includes Everybody's
Talkin, Both Sides Now, Until It's
Time for You to Go, Suzanne, Mr.
a "best of" LP in
The three dollar bill.
The stylus shown above is phony. It's represented as a replacement stylus for a Shure cartridge, and although it looks somewhat
authentic, it is, in fact, a shoddy imitation. It can fool the eye, but
the critical ear? Never! The fact is that the Shure Quality Control
Specialists have examined many of these imposters and found
them, at best, to be woefully lacking in uniform performance-and
at worst, to be outright failure' that
simply do not perform even to minimal trackabiility specifications. Remember that the performance of
your Shure cartridge depends upon
its patented stylus, so insist on the
real thing. Look for the name SHURE
on the stylus grip (as shown in the
photo, left) and the words, "This
Stereo Dynetic° Stylus is precision
manufactured by Shure Brothers
Inc." on the box.
Shure Brothers Inc.
222 Hartrey Ave., Evanston, Illinois 60204
In
AUDIO
NOVEMBER
1973
Canada: A. C. Simmonds & Sons Ltd.
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Bojangles, I Think It's Gonna Rain
Today and He Ain't Heavy, He's My
Brother.
GLUGGO (Vertigo, VEL-1015), a
recording distributed by Phonogram,
the new name for the Mercury cluster,
features a group that can do it hard or
soft, bluesy or countrified, dry or with
humor. It's together -rock, basically, with
easily understood lyrics. There are nine
cuts by the Spencer Davis Group, all
except the traditional Trouble in Mind
penned by a member of the quintet.
Highlights are Alone; Today, Gluggo,
Tomorrow the World, a great vocal less rocker showing the synthesizer's
scope at its best, and Mr. Operator,, a
smooth, harmonious rock special.
BUY
BEFORE YOU
THAT RECORD
..
MINSTREL IN FLIGHT (Kama
.
Sutra, SKBS 2069) is a good LP with
If it saves you disappointment over one poor purchase, it's well
worth the time to look in Schwann first.
lots of variety (though the emphasis is
on hard rock). Roger Cook is the star,
and he composed all but two of the ten
tunes. You can find fragments of slow
material, country and lots of moralizing. Cook's voice is rough 'n' tumble, a
sharp contrast to his lyrics, which
sound as if they stem from a flower
child who retains hope that the Haight-
Schwann -1 Monthly. Special new listing section has
latest releases: records, 8 -track cartridge and cassette
tapes. Nearly 45,000 total listings on 773 labels
in classical, recent popular, rock, jazz, musical
shows, country, opera, ballet, electronic,
quadrasonic, etc.
Ashbury syndrome isn't gone forever.
Best numbers on the record, distributed
by Buddah, are Eating Peaches in the
Sun, Carry On, Sad Stoned and an
anti -war, anti -Establishment treatise
reminiscent of some early Country Joe
stuff, The Power of Your Big Brother.
WAIT A MINUTE!
IS IT REALLY A BARGAIN?
IS IT THE PERFORMANCE YOU REALLY WANT?
Check the other performances and recordings in the latest
Schwann Record & Tape Guide.
Schwann -2
Semi-annual catalog for specialized
categories: pop more than two years old, classic jazz,
older and re-released mono and reprocessed stereo classical
recordings, classical on lesser -known labels, international
pop & folk on domestic labels, spoken, educational,
religious, etc.
SPECIAL PRICE SAMPLE OFFER
If your favorite store doesn't carry Schwann, order samples by mail.
Prices include postage and handling.
Schwann Sampler one Schwann -1 (monthly) and
one Schwann -2 (semi-annual)
Latest Schwann -1 (monthly)
Latest Schwann-2 (semi-annual)
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$1.25
for cost of handling also 8¢ stamped self-addressed long envelope.
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for the items checked above.
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HEAVY TRAFFIC (Fantasy, 9436)
sound track from an X-rated
full-length cartoon. Even if that category irritates you, the music should
soothe. Best are the replays, Sergio
Mendes & Brasil '66 doing Scarborough
Fair. the Isley Bros. and Twist and
Shout, the Dave Brubeck Quartet performing Take Five, and Chuck Berry
with the classic Maybelline. Other
material features Mel Saunders toying
with an original score by Ray Shanklin
and Ed Bogas. At worst, worth a few
spins!
is the
Lists 1,000 suggestions in classical music
by musical periods for your enjoyment. Send 15¢
I
LIVE AND LET DIE (United ArtUA -LA 100-G) is an original
soundtrack LP distinguished by the
presence of the chartbusting title tune,
a song performed by Paul McCartney
and his backup group, Wings. The
tune, written by Paul and his wife
Linda, can be heard on virtually every
pop radio station. The James Bond
Theme also is reprised here, more than
adquately. The rest, by George Martin,
is regular movie garbage-except for
the traditional Just a Closer Walk
With Thee, an updated version to be
sure.
ists,
Zip
Address
Schwann Record &Tape Guide
137 Newbury Street, Boston, Mass. 02116
AU
AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
NOVEMBER 1973
The BSR 710 has its brain in
its shaft. A carefully machined
STATEMENT OF OWNERSHIP
MANAGEMENT AND
CIRCULATION, Act of October 23, 1962. Section 4369
Title 39. United States Code
Date of Filing, Sept 19. 1973. 2 Title of Publication, AUDIO. 3. Frequency of Issue. Monthly; 4 Location
of Known Office of Publication. 134 N
13th Street.
Philadelphia, Penna. 19107; 5. Location of the Headquarters or General Business Offices of The Publishers,
134 N 13th Street Philadelphia Penna 19107
6
Names and Addresses of Publisher Editor, and
Managing Editor Publisher. Jay L. Butler, 134 N 13th
Street. Philadelphia, Penna. 19107: Editor, Eugene
Pitts III, 134 N. 13th Street. Philadelphia. Penna. 19107,
Managing Editor, none
7. Owner, North American Publishing Company, 134
N.
13th Street. Philadelphia, Penna. 19107.
I.J.
Borowsky, 134 N
13th Street, Philadelphia. Penna.
1
19107
8.
Known Bondholders, Mortgagees, and Other
Security Holders Owning or Holding
Percent or More
of Total Amount of Bonds Mortgages or Other Securities
1
metal rod holding eight precision molded cams. When the cam shaft
turns, the cams make things
happen. A lock is released, an arm
raises and swings, a record drops,
a platter starts spinning, the arm
is lowered, the arm stops, the arm
raises again, it swings back,
another record is dropped onto
the platter, the arm is lowered
again, and so on, for as many
hours as you like.
Deluxe turntables from other
companies do much the same
thing, but they use many more
parts-scads of separate swinging
arms, gears, plates, and springsin an arrangement that is not
nearly as mechanically elegant, or
as quiet or reliable; that produces
considerably more vibration, and
is much more susceptible to
mechanical shock than the BSR
sequential cam shaft system.
When you buy a turntable, make
sure you get the shaft. The BSR
710. From the world's largest
manufacturer of automatic
turntables.
BSR 710.
Shaft craft.
N one
9
Paragraphs 7 and 8 include, in cases where the
stockholder or security holder appears upon the books of
the company as trustee or in any other fiduciary relation.
the name of the person or corporation for whom such
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show the affiant's full knowledge and belief as to the
circumstances and conditions under which stockholders
and security holders who do not appear upon the books
of the company as trustees, hold stock and securities in
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and addresses of individuals who are stockholders of a
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the interests of such individuals are equivalent to
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the publisher's own and which are named in Sections
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R
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CATALOG
nd FM DIRECTORY
States Code).
Average no.
copies each
Single issue
issue during
filing date
nearest to
preceding
A.
Total no copies printed
(Net Press Run)
12 months
121114
118500
23058
82531
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Get all the newest and latest information on the new McIntosh Solid State equipment in the McIntosh catalog. In addition you will
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Paid circulation
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carriers. street vendors
and counter sales
Mail Subscriptions
Total paid circulation
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and D)
Office use. left -over
after printing
I
R!
M
s
w
II
a
,t
RI
gl
IN
a4ii4ttit ttrtttirt
985
AM TUNER AND PREAMPLIFIER
1826
Total (Sum of E and Fshould equal net press run
shown in
N
MX 113
FM/FM STEREO
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G
II
distributed to news
2. Copies
E.
388
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R
R' S
A)
121114
118500
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AUDIO
NOVEMBER 1973
99
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Classical Reviews
Edward Tatnall Canby
Power Biggs -Bach Organ Favorites,
Vol. 5. Flentrop organ, Busch -Reisinger
Museum,
Harvard. Columbia MQ
E.
31424, SQ,
The APL-9 Reflecting Speaker
System combines contemporary
styling with the latest in sound
technology. It is available with
either an inlaid synthetic slate
top or an oiled wa nut top. In
appearance, size, and versatility
of room placement, the APL -9
will enhance any decor.
The APL-9, pentagonal in
cross section, utilizes 9 identical.
acoustically coupled full range
51/4" high compliance drivers.
The efficiency of the APL -9
permits effective Lse with
amplifiers and receivers capable
of delivering only 20 watts r.m.s.
per channel while having a
maximum power handling
capacity of 110 watts r.m.s. each.
All APL speakers carry a
lifetime guarantee to the
original owner.
APL-9
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6.98.
I played this quadraphonic disc late
last summer on the latest "3 -chip"
SQ logic decoder, especially installed
in my system at the time. The results
were, I must admit, impressive. The
new decoder is a clear improvement in
the continuing sophistication of the
matrixing system.
The biggest fault of any matrix arrangement, with or without logic, is a
variable overlap of signal in the room sound aspect of the recording which
tends to create a curious standing -wave
"hump" of sound overhead, in the
middle, a four-way mono component
that does not belong there and, for a
careful ear, is a real distraction and
distortion. In the earliest matrix decoding this effect was unpleasantly
noticeable. With increasing sophistication, first in straight matrix circuitry,
then with the extra aid of logic, that
central hump of sound has, so to speak,
been gradually reduced, flattened and
spread out, and the over-all quadraphonic effect has been correspondingly
improved.
I still can hear some of it via this
latest decoding from CBS, though its
presence depends in part on which recording you play. But it has definitely
been reduced to a new "low" and the
sound in four channels is correspondingly much better. Even in older SQtype records. No logic "pumping,"
audible jumps from back to front and
the like, either. In this big organ recording, the sound is dramatically good,
perhaps because of the nature of organ
sound in a reverberant space, already
so gloriously mixed-up that a sonic
"hump" would have trouble maintaining itself!
Without any question, the RCA-type
Quadradisc ("discrete") can do a still
better job, sound for sound, in this
particular facet of quadraphonic reproduction. There simply is no argument
on that score. There is no hump. The
reverb is reproduced naturally as a
real space. That superiority is at a
multiple price which we are still all of
us evaluating-secondary problems of
expense, equipment availability, broadcasting, disc cutting at slow speed, and
the direct problems of lowered levels,
necessary tonal adjustments, the residue
of distortion and so on. But so long as
the "discrete" disc can give us humpless
four-way sound, and so long as the
matrix disc decoders continue to improve
in their subtlety, the matrix-discrete
arguments will go happily forward.
More power to them.
(Biggs? He is always at his best when
he has a really good organ to play.
This modern instrument is his own, at
home base; he plays it with gusto and
appreciation. Good Bach, well registered and beautifully recorded.)
Performance:
Beethoven's Greatest Hits. (Ode to
Joy, parts of Fifth Symphony, Moonlight Sonata, etcetc.) Assorted CBS
Columbia MQ
orchestras, soloists
...
32056, SQ, $6.95.
The point to be made concerning this
potpourri of reissues in SQ is that quadraphonic recordings-any system-can
be constructed very nicely out of older
catalogue items going back a good
many years. Columbia, if I am right,
has been doing all its classical in 8 track for umpteen years and presumably other majors have too, at least on
this side of the Atlantic ditch. A fourway mix -down, brand new in effect,
can be made just as readily as the conventional two-way mix -down. That is
what we have here, from the Philharmonic, the Philadelphia (pre -RCA),
Philippe Entremont, the Morman Tabernacle Choir. It's not a Beethoven disc
for dedicated Beethoven listeners but it
is an excellent example, which happens
to be in the SQ matrix format, of the
kind of new -type recording which can
be made from thousands and thousands
of older tapes which were not specifically intended for quadraphonic sound.
The only question, I think, is-do
these constitute "reprocessed" quadraphonic? Not to my opinion. The "reprocessed" stereo disc is a mono original, one channel, which has been made
into two, a mix -UP. No pun intended;
AUDIO
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Sound: B-
B
NOVEMBER 1973
some of them are excellent. This SQ
disc is simply a new mix -DOWN.
There are dozens of them and soon
will he hundreds.
Brahms: The Complete String Quartets (Op. 51, Nos. 1,2; Op. 67). The
Cleveland Quartet. RCA VCS 7102,
2 discs, stereo, $1 .96.
1
It had been a long time since I had
heard these three quartets-they have
not been very stylish in recent years.
But now, with the supposed "Romantic
revival," they are back and, of course,
high time if we are to have any music
at all for plain old string quartet, un amplified! But I find them, for my
somewhat ancient ear, very strange
performances of familiar music. Definitely, of a new generation with a new
point of view.
The Brahms chamber music is tough
stuff, extremely strong minded, rigorous,
compact, dedicated, and nowhere more
than in the quartets. They were far
more modern, at the time, than was
then conceded-especially by the Wagnerian school of German music, which
disapproved of virtually any music that
made use of traditional formats and
structures. As Brahms had it, the great
shadow of Beethoven, looming ominously, spurred him to ever greater
intensity. The great performances of
the early 20th century maintained this
tradition as a matter of course. I very
well remember these quartets as the
scratchiest, hardest -worked pieces in
the repertory-the strings seemed almost
hoarse with the sheer effort of projection and I always felt that Brahms had
outdone the medium itself-these were
symphonies, concerti, at least in their
intensity, trying to get through the small
voices of the quartet.
Now what? The Cleveland Quartet
is young, long haired, bearded, and like
many younger people, honest in their
convictions; they have worked out
their own feelings about this music and
to heck with traditional ways of play.
That guarantees interest. Instead of that
rigorous, almost hard intensity I remember, here we find what I can best
call a gentle approach. Gentle-for
Brahms! Crazy. The man was possessed
of a demon, a puritan conscience, to
drive him forward; his marvelous sense
for melody was the foil that kept drama
alive. And yet these people play him
gently. No better word for it.
Not really good for Brahms. There
is no long line, no sustained shape;
all is expressive, pulsating, emotional
non -drive. It is a Baroque sound in
Romantic guise, the melodies almost
EPI'S LINEAR SOUND.
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*In Illinois, the toll -free number is 800-322-4400.
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lost in their accompaniments, the counterpoints unemphasized when two
melodies play at once-which is often
and should be emphatic in any 19th
century music. And the rigorous climaxes, the returns of major ideas, are
treated in pleasantly casual fashion,
rather than as great fulfillments of
high-level formal construction. Nopethis isn't the old Brahms. It's a sort of
flower-child version.
A criticism? Only in that some aspects of the music are unrealized. The
solo melodies are very seldom given
the prominence they need. The first
violin, always the leader, is almost
apologetically modest. The super -intense moments, not set off by the melodic parts, aren't really intense, and
so on. My feeling is that the very
honesty of these interpretations is both
their best quality and their main
fault. Most young quartet players
slavishly imitate the Budapest Quartet
(or the local conservatory faculty
quartet-which usually has done the
same) and so acquire a technically
correct interpretation that sounds right
and is pure fake-until they grow into
it for themselves. I think this is the
better way, by far.
The fact is, though, that these young
people haven't really found Brahms
yet. When they do, they'll be terrific. In
their next recording.
Performance: B-
Liszt:
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Mountain Symphony; Male-
diction
for Piano and Orch.; La
Lugbre Gondola. Alfred Brendel, piano;
Vienna Symphony, Gielen; Music for
Westchester Symphony Orch., Landau.
Vox Turnabout TV -S 34518, stereo,
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Vox's Turnabout series, the lowpriced offering, is an intelligently produced series combining relevant recordings that are both old and new. The
piano solo about the lugubrious gondola
here, for instance, is simulated stereo,
the rest "real" stereo-I wouldn't have
noticed the difference. The excellent
Austrian pianist Alfred Brendel is the
musical binding force along with old
man Liszt himself, represented here in
early, middle and late music.
The big symphonic poem subtitled
Ce qu'on entend sur la Montagne (What
one hears on the mountain) remains a
sprawling mood work of a sort still too
corny sounding for our sophisticated
ears, though it was-for the revolutionary ears of 1848-undoubtedly quite
sensational. I'd say that the Westchester -based orchestra under Landau does
a remarkably good job with it, all things
considered. The Malediction, very
rarely heard music, is another of those
lugubrious Liszt pieces that are often
his best-it isn't exactly easy listening,
either, but makes its dismal points in
the gloomiest fashion. The funereal
gondola is a late Liszt piano piece, one
of those that now appears as advanced
experiment in atonality. Extraordinary
for its day and once again it marks
Liszt as the first of the German modernists, far ahead of the much later Richard
Strauss in harmonic terms.
Performances: A-
Sound: B -
Liszt: Piano Concertos (No. 1 in E
Flat; No. 2 in A). Ivan Davis; Royal
Philharmonic, Edward Downes. London
SPC 21081, stereo, $5.98.
London's Phase Four recording-no
connection with quadraphonic-is well
known for liberal microphoning for
advanced effects. Here, the projection
AUDIO
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Sound: B -
NOVEMBER 1973
of the piano solo is very liberal, at the
expense of the orchestra. OK; so Liszt
was a pianist and so is our star, Ivan
Davis. Even so, the music is not well
served by being treated as solo piano
music, close-up. Even though, admittedly, you can also hear the orchestra.
Davis is a fantastic technician and a
solid musician. Thus his Lisztian pyrotechnics are just that, tossed off as
though they were no problem at all,
which indeed they aren't. But the whole
thing is a bit on the cool side (in an old
fashioned sense). An excellent and
workmanlike set of performances, impeccable, but never magical. Somehow, Liszt himself must have thought
they were magical. Otherwise he could
not have composed such floridly Romantic stuff! Some performers can still make
the stuff sound like magic, but it isn't
easy these days.
The first of the concerti is the familiar Triangle, played to death a generation ago and recently given a healthy
amount of rest. The second, like the
he doesn't want to. Sometimes this is
good. Sometimes it means you can
ignore your audience. Is that good?
A question.
This disc, like many, is both difficult
and interesting. For one thing, it's
funny. William Mayer is a (relatively)
conservative composer who has a real
quirk for offbeat humor, even if its
inspiration can be traced, say, to Stravinsky's Histoire du Soldat way back
in 1918. The Brass Quintet is a very
spunky piece that spits in your face
the instant you put it on. Rather nice.
\
®o
ai .
"other" Tchaikovsky concerto (and part
of a third), is less familiar because
less immediate in appeal. This one is
built on an often-repeated series of
chords that tend to drive you nuts after
awhile. Davis does commendable things
in postponing that particular happening.
He doesn't try to say-see, listen, there's
that set of chords again! Too many
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Composers. Catherine Rowe, sop.,
Vern Sutton, ten., Jeffrey Van, guitar;
Iowa Brass Quintet et al. CRI CD 291,
stereo,
S
5.95.
Our 53rd
CRI (Composers Recordings, Inc.)
continues to pour out its LPs of contemporary music, far beyond any quantity we can review short of dropping
Bach, Beethoven and Brahms for ever.
So I sample one every so often-it's
always interesting. But I end up hearing
double, mostly. Never know what's
coming next, nor what sort of musical
bedfellows will be plunged together on
the one LP. CRI runs a prepaid operation, so to speak, managed largely by
composers and musicians themselves,
financed by major foundations, and
thus nobody has to be "commercial" if
AUDIO
NOVEMBER 1973
LAFAYETTE
1974 CATALOG
The World's Largest
Consumer Electronics Catalog
B-
William Mayer: Brass Quintet; Miniatures; Two News Items; Khartoum.
Dominick Argento: Letters from
jl!,'
LAFAYETTE
pianists do.
Mr. Downes and the orchestra do
a good job but the focus is on the
piano, especially in the second of the
two works.
Performances: B-
The six Miniatures are for spunky
soprano, who squeaks, sings, sputters
and talks her way through satirical
little texts à la Dorothy Parker. One of
the News Items is entitled "Hastily
Formed Contemporary Music Ensemble
Reveals Origins." That's Mayer for
you. Not exactly of the new neo Romantic generation.
Is it the name which makes me sense
an Italianate intensity in Dominick
Argento's settings of actual letters by
such diverse composers as Chopin,
Mozart, Debussy, Puccini? Very lyric,
LAFAYETTE 1974 CATALOG 740
Stores From Coast-to -Coast
Year
MAIL
THE
COUPON
TODAY
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P.O. Box 10, Dept.
27113
Syosset, L.I., N.Y. 11791
Send For Your Free Lafayette Catalog Today!
Send me the FREE 1974 Lafayette Catalog 740
27113
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for the tenor, and passionate too. Excellent guitar accompaniment. But I was
somehow confused to hear Chopin,
Mozart, then Debussy all "speaking the
same language"; it didn't seem quite
convincing. Not even for Puccini. I kept
hearing Mr. Argento, even when he
quoted a bit of actual Schubert in
Schubert's letter. The seven letters take
up the whole of side 2, with Mayer
occupying side 1.
Performances: B-
Sound: B-
Handel's Overtures. English Chamber
Orch., Leppard. Philips 6599 053,
stereo,
S
6.98.
Imagine it-all these weird Handel
names. You've heard the Overture to
"Messiah" no doubt and maybe "Israel
in Egypt"; you might know a few
Handel opera names too-"Alcina,"
perhaps. But here we have a raft of
total unknowns, and I'll omit the quotes
just to get them down more easily:
Lotario, Admeto, Orlando, Poro, Partenope, Ottone! Every overture is the
take-off point for an evening-long opera
and there are plenty of others available, in case they want to make a
Volume 2, or 3.
Superb music. Needless to say. The
trouble with Handel has always been
that he wrote too much, and people
wanted to hear "Messiah" or the Water
Musick. So, like some bumper wheat
crop, the rest of Handel has been stored
away unused. These overtures are
mostly what we later on have called
Baroque suites, a splendid, stately
introduction with the well-known dotted
rhythm, ta-dum, ta-dum, followed by
fast music and very often several additional dances, slow and fast, no doubt
to get the people seated and ready for
serious matters on the stage. The English
Chamber Orchestra has achieved 95
percent spontaneity in playing the
dotted rhythm the way it must be
played-short, snappy-instead of as it
is written down. Double dotting, we
often call it. They really do the job as
though it were taken for granted, where
most orchestras still sound surprised
and annoyed, not really believing their
conductors who tell them, don't play it
the way you see it on the page, play it
this way.
Better play one side at a time. It
wasn't Handel's intention to line these
overtures up in a row, one after the
other, after all.
See classified section in the back of this issue
for rates and to place your ad.
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Performances: B+
Sound: B+
AUDIO
NOVEMBER 1973
(Continued from page 46)
had a pronounced wearing effect on
cassette heads. Chromium dioxide
tapes also require about 40%-50%
additional bias current.
The most sophisticated cassette recorder-players have a three -position
switch. In addition to "regular" and
"CrO," positions, there is a third
position for "low noise" or "extended
range" cassettes, such as TDK's ED
or SD cassettes. While these tapes, as
mentioned earlier, can be used with the
bias switch set to the "regular" position,
on cassette recorder players having a
3 -position switch, it is preferable to
set the bias switch to its "low noise"
position to take advantage of the higher
bias current provided.
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Walnut case is standard, or two units may be ganged
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Model 157 is two channel, simultaneous record and
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Available from professional audio dealers or direct
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Equalization
The bias selector switch doesn't just
change the bias; it also changes equalization, and this is a whole 'nother
story. Equalization is electronic compensation made for the tape's frequency response curve. If the curve
droops sharply at the high end, equalization circuitry will boost this drooping
section electronically. If it rises or
drops too sharply at some other point,
equalization will flatten the variation.
Ordinarily, equalization is standard
on cassette tape decks. For regular and
premium -grade tapes, it's there during
both recording and playback. The playback conforms closely to the NAB
standard for 71 ips open -reel tapes
and because of this, cassettes recorded
on one machine can usually be played
back on any other cassette recorder
with no significant differences in
equalization characteristics.
With chromium dioxide tapes you
may have to be a bit more careful.
Each manufacturer has his own standards for equalization and bias changeover. Whilg the bias selector switch
also changes the equalization, there is
no machine -to -machine standard and
so the safest procedure is to record and
playback on the same machine.
Which Tape To Use
With the proliferation of cassette
tapes and adjustable bias controls on
cassette recorder players, there is an
excellent opportunity for confusion.
The choice, however, is quite simple. If
the recorder has a CrO, bias position,
use this only when playing CrO, tapes.
If the recorder has either fixed bias
or a three -position switch, you can use
cassette tapes such as TDK's ED or
SD with the bias switch positioned to
low noise or extended range. It is important to remember to record and
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playback at the same bias level.
AUDIO
NOVEMBER 1973
105
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AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
.
NOVEMBER 1973
FOR SALE
FOR SALE
AUDIO RESEARCH CORP'S Magneplanars IA,
Il, and Ill, Woofer Screen'', SP -3 Preamp',
EC -2,3 and 4 Crossovers', Dual-51, 75, and 400
Amps, Tone Arm*. Normally shipped from stock,
MEMORIES SEMICONDUCTORS FREE FLYER,
UTI, P.O. Box 252, Waldwick, N.J. 07463.
pre-paid insured. Music & Sound Ltd., 1111 Old
York Road, Willow Grove, Pa. 19090. 215-
ELECTROENCEPHALOPHONE: brainwave monitor. Professional biofeedback instruments. J&J.
Rt. 8, Box 8102, Bainbridge Island, Wash.
659-9251.
98110.
ENGINEERS, COLLEGE
THE INVENTORS,
INSTRUCTORS AND PROFESSIONAL MUSICIANS at Music & Sound Ltd. offer their clients
a new standard of technical competence, certain
proprietary testing procedures, a mind boggling
research laboratory, and a host of the most
advanced professional services, including hand
matching/customization/
component
picked
assembly/alignment, room acoustical design and
treatment, calibrated environmental equalization. zt 1 db at your ears, total "A" warranty
station service, and the most flexible demonstration facilities anywhere for the distinguished
array of products from: Sequerra, DaytonWright, Dahlquist, Infinity, Crown, Decca, I, M.F.,
Quad, Rogers, Spendor, B.B.C. Monitors, Stax,
E.S.S., B&O, J.B.L. and Altec. Professional,
Schoeps, S.S.I., Beyer, Custom Rabco, Gately,
Braun, Tascam, Ohm damped S.M.E., Ortofon
QL-15, Tandberg, shipped pre -paid insured.
Music & Sound Ltd., 111/2 Old York Rd., Willow
Grove, Pa. 19090 215-659-9251.
CONNECTICUT AREA Audio Research speaker
and amps. Dyna-mod kit and Transcripter turntables. The Stereo Lab, 168 State St., New
London, Conn. (203) 447-9802.
TWO (2) WHARFEDALE W-90 loudspeaker
systems, a stereo pair. Must sacrifice, moving
Call (201)
out of state. Very reasonable.
941 -1768 -AM ONLY.
PROTECT YOUR LPs. Poly sleeves for jackets
60 round bottom inner sleeves 50 Poly lined
paper sleeves 120 White jackets 270 Postage
$1.00. House of Records, Hillburn, New York
10931.
CIZEK LOUDSPEAKERS Lowest price in the
country. Quotes on your favorite system. Sound
Center, Box 1242, Bloomington, Indiana 47401.
812-332-4252.
PHASE
RADFORD,
RESEARCH,
CROWN, QUAD, ALTEC, INFINITY,
REVOX, BRAUN,
GRACE, AKG,
PANASONIC SP -10, ESS, TANDBERG and
many more. Hartley Electronics (Audio Consultants) 1502 Butternut, Richland, Wa. 99352.
(509) 947-5026 after 5 p.m. weekdays, all
day weekends.
AUDIO
LINEAR,
DECCA,
SPEAKERS CUSTOM BUILT Folded or straight
axis horns for the perfectionist. These horns will
provide the finest sound in the world. Duluth
Electronics Co., 24 East 1st, Duluth, Minnesota
55801. 218-624-4153.
AUDIO RESEARCH, BRAUN, CERWIN-VEGA,
DECCA, ESS, HEGEMAN, IMF, MAGNUM
OPUS, PHASE LINEAR, QUAD, QUINTESSAE, STAX.
SENCE, RABCO, RADFORD,
Paul Heath Audio, 354 State Street, Rochester,
N.Y. 14608. (716) 232-2828.
FLORIDA AUDIOPHILES! E.S.S. AMT 1; Phase
Linear, Klipsch, Sony, Marantz, B & O, Quad,
Revox, Barzilay. INTERIORS PLUS SOUND
3038 N. Federal Hwy., Ft. Lauderdale, Fla.
33306. (305) 566-3511.
ACCESSORIES Gately
Pro kits and mixers. Most models in stock. Immediate prepaid shipment. Mastercharge. Write
or call Dick McGrew Recording Service, 7027
Twin Hills, Dallas, Texas 75231. 214-691-5107.
NEUMANN MICS &
DIAMOND NEEDLES and Stereo Cartridges at
Discount prices for Shure, Pickering, Stanton,
Empire, Grado and ADC. Send for free catalog.
All merchandise brand new and factory sealed.
LYLE CARTRIDGES, Dept. A, P.O. Box 69,
Kensington Station Brooklyn, New York 11218.
AUDIO
We Don't Have Gimmicks
Just Low Prices
Southern
Sound
Wholesalers
Every Major Brand
STEREO COMPONENTS Lowest discounts. $1.00
for catalog. Defa Electronics, 2209 Broadway,
N.Y., N.Y. 10024, Tel.: 212-874-0900.
Mail Order Discount Prices
Same Day Service
PROTECT YOUR RECORDS. Cardboard replacement covers, plastic lined sleeves, 78 and 45
heavy sleeves, hinged record set boxes, 12", 10",
7". Cabco, A-4, 89 East Woodruff, Columbus,
Ohio 43201.
Memorex
Garrard
SCOTCH MAGNETIC TAPE, discount Box 167A,
Orwigsburg, Pa.
101/2' RECORDER SPECIALISTS: Used boxed
101/2" metal and fiberglass recording reels NAB
center Metal $2.00 each fiberglass $1.25 each.
To Mention a Few!
mil quality tape on above metal reel 5
for $24.00 on fiberglass 5 for $19.00. Replacement content labels for 10'1" tape box samples
$.25. Soundd Investment Co., POB 88338,
Dunwoody, Ga., 30338.
New
-Dynaco
Sherwood
Koss
ADC
KLH
-Shure
-Scotch
Miracord
"Ask For A Quote"
1
ROGERS B.B.0
MONITOR, IMF, B&W Ltd.,
Celestion, Radford, Decca, ERA, Connoisseur,
Audionics TL-90, Goldring, Revox, Beyer, Lamb
and more. Custom design and modifications.
SUFFOLK AUDIO, INC., 120 Boylston St., Suite
220, Boston, Mass. 02116. (617) 423-2051.
PROFESSIONAL AUDIO EQUIPMENT: Microphones, recorders, equalizers, limiters, turnmastering
tables, lathes, cutterheads, disc
systems, portable mixers, consoles, alignment
tapes, Package deals and installations. Request
Flyer. Wiegand Audio, Middleburg, Pa. 17842
717-837-1444.
IMF SPEAKER SYSTEMS -ORDER DIRECTLY
FROM PHILA. Monitor, $900; Studio, $400;
ALS -40, $300. All models shipped immediately
from stock, prepaid. Barclay, 503 Haverford
Ave., Narberth, Pa. 19072. (215) 667-3048.
AT
COMPONENTS
CANADIANS-DYNACO
TREMENDOUS DISCOUNTS. Write En -Jay Sales,
Hornepayne, Ontario.
WORLD'S FINEST LOUDSPEAKERS on DEMONSTRATION -AUDIO RESEARCH CORPORATION'S
NEW T -1A, T-II, T -III; DAHLQUIST PHASED
ARRAY, IMF MONITOR III, STUDIO Ill, ALS
40, ESS AMT -1, RTR 280DR, ESR-6, CERWINVEGA
320 MT -320C, HEGEMAN, QUAD.
BROCHURES AVAILABLE. PAUL HEATH AUDIO,
354 STATE, ROCHESTER, N.Y. 14608. (716)
232-2828.
TWO SENNHEISER MKH-105 MICROPHONES
with accessories as new. Stellavox SP -7. Both
bargains. Hyde, 301 Springdale, Wintersville,
Ohio 43952. (614) 264-4987.
+-x+
CALCULATOR OWNERS: Compute
square roots, trigonometric functions, logarithms,
exponentials and more! Quickly, accurately,
easily! Manual $2.00. Send today-Unconditional
money-back guarantee. Mallmann Optics and
Electronics, Dept. A2, 836 South 113, West
Allis, Wisconsin 53214.
AR, KLH, ADVENT, DYNACO, RECTILINEAR,
ADC OWNERS -Our low cost electronic equalizer
adds a full octave of new bass, provides three
broadband tone controls. Three reviews, literature,
from NORMAN LABORATORIES, 520 Highland
Parkway, Norman, Oklahoma 73069.
0. Box 44
Magnolia, N. J. 08049
P.
Check No. 58 on Reader Service Card
FOR SALE
MAKE A SOUND CHOICE. Our switching equipment allows instant comparing of all our products:
Audio Research, Magneplanar, B&O, Braun,
Crown, DBX, Decca, Infinity, Phase Linear,
Rabco, SAE, Soundcraftsmen, and many more.
SOUND SYSTEMS
Palo Alto, Calif. (415) 328-3761.
Mill Valley, Calif. (415) 383-6556.
FLAT FREQUENCY RESPONSE TO 18Hz.
Sound Systems presents its new Earthshaker One
woofer system. The system includes an electronic
crossover variable from 20 to 300 Hz and 100
watt rms amplifier.
SOUND SYSTEMS
Palo Alto, Calif. (415) 328-3761.
Mill Valley, Calif. (415) 383-6556.
SCOTCH 150 STUDIO TAPE -1800' on 7"
reel degaussed and boxed. 12 for $12 POSTPAID.
Free price list. WIDE RESPONSE, 6114A SANTA
MONICA BLVD., HOLLYWOOD, CALIF. 90038.
ARE YOUR TAPES BEING SPOILED by recording or playback on equipment that may be
magnetized? The magnetic signal "printed" on
tape is quite sensitive to subsequent magnetic
field exposure. You can now actually measure
such damaging residuals and really demagnetize
offending components using an Annis Audiophile
Han -D -Kit. Write for bulletin & copy of article
"Notes On Demagnetizing". R. B. Annis Co.,
1103 N. Delaware, Indianapolis, Ind. 46202.
HAN-D-MAGS, Audiophile Han -D -Kits and Magnetometers -Free Data. R. B. Annis Company,
1103 N. Delaware, Indianapolis, Indiana 46202.
SONY 854-4S (Sync) Quad Tape Deck $ 1350
or make offer. Mint Condition.
SONY 850-2 Stereo Tape Deck (Y2 Track, 334 ips,
711 ips, 15 ips; 101/2" reels)
$650 or make offer. Mint condition.
Appalachia Sound Recording Studios
Route #8, Box 525
Chillicothe, Ohio 45601
Phone (614) 663-2544
107
NOVEMBER 1973
www.americanradiohistory.com
AmericanRadioHistory.Com
SCOTCH BRAND
CASSETTES
LOW NOISE/HIGH DENSITY
(LN/HD)
or HIGH ENERGY/COBALT
1-9
10
48
SC-45-LN/HD. 45 min
1.35
121
1.15
SCL45-HE, 45 min
'SC-SO-EN/HD. 1 hour
'SC -60 -HE. 1 hour
"SC-90-LN/HD, lYhrs
"SC -90 -HE. 114 hours
SC-120-LN/HD. 2 hours
1.55
1.48
1.40
1.48
1.65
2.16
2.48
1.35
1.57
1.21
2.02
2.32
1.92
3.00
2.57
2.49
'Buy
1.49
2, 60 or 90's, GET ONE FREE
*207-R90
NEW FACTORY FRESH SCOTCH LOW NOISE 212-R90;
REELS 1800 FT.
1
MIL POLYESTER); SCOTCH
FOOT 10-1/2 METAL REEL); OR AMPEX
#641,
QUANTITY
#211.R90 SCOTCH 7"
#2O7 -R90 SCOTCH 7"
#641-I8 AMPEX
r, 1800
FT.
203-36 SCOTCH 10-'4" METAL NAB
FOR SALE
CUSTOM DESIGNED Four-way walnut finished
corner horn enclosures, (only one of its kind).
2.22
OPEN REEL TAPE RIOT
(7"
FOR SALE
IMF MONITOR MK II SPEAKERS, 8 months
old, pair $950. FIRM, Pat Minichello, 2960 West
8th Street, Brooklyn, New York 11224, (212)
946-3572.
(HE)
QUANTITY
*203
1800 FT.
7
(3600
INCH REEL
1-9
10
36
3.32
2.92
2.77
3.83
3.34
3.17
1.95
1.83
1.69
7.95
7.00
6.79
CASSETTES & REELS ASSORTABLE FOR BEST QUANTITY PRICE
SHIPPING/HANDLING +10%, 7% OVER 620.00, 5% OVER $70 00.
SCOTCH MAGNETIC TAPE (USED)
*150. 1800 ft., 7 inch reel,
mil
1
polyester, recorded once, bulk erased
(no box), 99C, plus 10% shipping
& handling (min. order. 010.00); slightly
used 10-1/2 inch fiberglass reels. 3"
hole, 50C, metal. NAB, 0 1.00 each
(plus shipping by weight and zone)
SAXITONE TAPE SALES
9
-
re.
i
Ai
1776 Columbia Rd., N.W., Washington, D.C. 20009
FOR SALE
DECCA MK V EXPORT -HAND SELECTED.
Custom lateral damping for SME tone arms (for
maximum performance).
SOUND SYSTEMS
Palo Alto, Calif. (415) 328-3761.
Mill Valley, Calif. (415) 383-6556.
RECORDING STUDIO AND TUNED ROCK PA'S,
100's of professional products (J.B.L. and Altec
Professional. Tascam, D.B.X., U. R.E.I., Gately,
etc., etc.) and customized touring sound systems,
including feedback suppression, narrow band
(5HZ!) acousta-voicing/equalization (,1 db at
your ears), room design/measurement/treatment.
All shipped prepaid insured from Music and
Sound Ltd., 111/2 Old York Road, Willow Grove,
Pa. 19090.
INVENTORS -ENGINEERS
SONY TA-3120A, $120. R.C. Nuebling, 519
Sixth, Ann Arbor, Mich. 48103.
PRE-RECORDED EIGHT -TRACKS, CASSETTES.
Excellent condition, reasonable prices. Free lists.
F. Payar, 1234 Taylor Ave., New Kensington,
Pa.
15068.
LOUDSPEAKERS -BOSE 901 REPLACEMENTS.
$6.98 postpaid. Quantity Discounts. Moneyback
guarantee. Auratone, Box 580-2, Del Mar,
California 92014.
THE
LARGEST OLDIES CATALOGUE. Over
6000 records for sale 50C to $150.00 covering
years 1948-1972. Cost of 60 page catalogue is
$3.00 refundable with the first order. Send to
Collectors Records, Box 44017 Dallas, Texas
75234.
Brushes list $ 12, now S6. Two Lowther PM6
drivers plus Acousta plans $ 100. R. Goewey, 3345 92nd St., Apt. 5G, Jackson Heights, N.Y.
MONITORS, STUDIOS, ALS-40 loudspeakers stocked. IONOFANE speaker system
with Ionic High Frequency units, value $1,200
pair; now just $885 for the pair. Genuine Decca
SC4E cartridge, $125 value just $89.95. Decca Kelly Ribbon tweeters just $85.00. Futterman
tubed 100 watt per channel amplifier $410.00.
SAE -MK 4B amplifier, mint $255.00. We take
trades. Audiocraft, South Rockwood, Michigan
48179. Telephone: (313) 379-9945.
BUY DIRECT FROM ENGLAND'S HI FI MAIL
ORDER SPECIALISTS! SAVE ON SME, LEAK,
QUAD, RADFORD, BANG & OLUFSEN audio
components of superb quality for connoisseur.
Audio Imports. 5557 Versaille Dr., Indianapolis,
LOWEST DISCOUNT PRICES ANYWHERE
on audio equipment. All major brands discounted. Write for quotes; K&L Sound Services,
264 N. Beacon St., Watertown, Mass. 02172.
TRANSCRIPTORS, STYLUS SCALES, SWEEP
ARMS: each list $15, now each $8; Stylus
11372.
DECCA, TANDBERG, REVOX, GOLD SPEAKERS,
B & W,
CELESTION, TRANSCRIPTOR, CAMBRIDGE, A & D. B & O, STAX, WHARFEDALE,
ELECTRO -STATIC SPEAKERS, ORTOFON, ETC.
INSURED SHIPPING QUOTES FREE OR SEND
$2.00 BILLS TO INCLUDE LITERATURE. GOOD WIN LIMITED, 7 BROADWAY, WOOD GREEN,
LONDON N. 22. VISITORS WELCOME TO SHOWROOMS. PHONE 888-0077.
SCOTCH
RECORDING TAPE, lowest prices.
TAPE CENTER, Box 4305B, Washington, D.C.
20012.
IMF
Ind. 46227.
50
WHOLESALERS -COMPONENTS,
TV'S,
CALCULATORS! $1.50 AUDIOSALES, BOX F39,
BLUEPOINT, NY 11715.
PHASE LINEAR 400 $450, MARANTZ 7T $175,
MARTIN KRYPTON speakers $300 pr., HARTLEY
CONCERTMASTER VI $500, CITATION 12 $250,
RADFORD SC-24 $325, SPA50 $290, QUAD 33
and 303 $365, BRAUN TG 1000 $735, GATELY
Pro -Kit Mixer $295, BOSE 901's $365 pr.,
BRAUN 810 Walnut $595 pr., RABCO SL8E
$145, SAE Mark & III $440 each, DECCA London $70, HADLEY Power amp $250, ADVENT
Dolby model 100 $ 145, RABCO ST4-ADC 26
$145,
INFINITY
SS -I
(Improved) $1335,
CROWN DC 300 $500. All above used equipment
in excellent condition.
AUDIO SYSTEMS &
DESIGN 5421 South 84th St., Lincoln, Nebraska
68516 (402) 489-9888.
I
QRK AND REK-O-KUT professional turntables,
tone arms, accessories. Isostatic Audio Systems,
66 Dale Drive, Tonawanda, New York 14150.
(716) 695-1535.
MAGNEPLANAR© LOUDSPEAKERS are extremely realistic sounding. Our top quality models
are sold thru AUDIO RESEARCH dealers, some
of which advertise on these pages. We now
have two less expensive models for sale. They
are the MG 1672-P Room Divider and the
MG2167-F Floor Standing model. You may buy
direct from the manufacturer until there is a
dealer in your area. Write us for details. Magne pan Inc., P.O. Box 8642, White Bear Lake,
Minn. 55110.
SENSATIONAL
NEW
CLEANER removes dust
sound. Battery operated.
or money refunded, $
residents add sales tax.
VACUUM
RECORD
and pollution for better
Satisfaction guaranteed
10.95 postpaid. Calif.
Ruxton Electronics, PO
Box 30312, Santa Barbara, Calif. 93105.
SERVO-STATIK I
Electrostatic Stereo Speaker System. Excellent
condition.
Very transparent. Wide
dynamic
range. Very low distortion. Costs $2000 new.
Sacrifice $995. Larry Beiter,
3829 Logans
Ferry, Pittsburgh, Pa. 15239. Call (412) 327-
7193.
SOLID STATE LOW FREQUENCY generator
for sync motor amplifier. Dual 50 watt solid state
amplifier. Colortran Multi -6 light. Pentax 35mm.
camera equipment. Many other excellent items
from recording company closeout. Write for
complete list. M. E. Boyd. 903 Salmon Drive,
Dallas, Texas 75208.
108
Electronic x-overs, Cit. A, 4-Cit. B's. Photo and
technical report to interested parties. Blaine Irwin,
27046 Laverne Court, Highland, Calif. 92346.
(714) 862-4356.
KARLSON-Fantastic new line of patented
advanced technology speaker systems for stereo.
p.a., and music now available. Write Karlson
Research & Mfg. Corp., Box 117, W. Hempstead, N.Y. 11552.
OPERA TAPES. Historical performances of past
40 years. Unbelievable treasures and rarities.
ALSO LP RECORDS. Free catalog. Ed Rosen,
Box 97, Freeport, N.Y. 11520.
AUDIO RESEARCH -DUAL 51 amplifier w/fan,
and PC -1 crossover. Soundcraftsmen 20-12
equalizer. All components new in mint condition.
Transferable warrantys. Best offers.
D. Thompson
2639 Moderna Court
Rancho Cordova, Ca.
95670.
(916) 363-9054
ALTEC'S FINEST SYSTEM. 724A TunerPreamp with two 2873A Barcelona Biamp speaker
systems. $1,400.00 Thorens TD -125B Turntable with Rabco SL -8E Arm and B&O SP -12
Cartridge. $350.00. Soundcraftsmen
20-12
equalizer. $200.00. All units in superb condition.
Bob Eastwood 3725 Garfield, Lincoln, Nebr.
68506. Call anytime (402) 489-4158.
McINTOSH MC -2300, 600 watt power amplifier
-$1100. McIntosh C-26
cabinet -$300. Both used
warranty. Pair KLH-9's, used
Prices less shipping. C. Elmore,
Key West, Florida 33040.
AUDIO RESEARCH SP -2C PREAMP $300.;
Audio Research Dual 100c amp. $800.; SAE
Digital Tuner MK6 w/cabinet $600. Dr. M.
Fisher, 4015 Jefferson Hgwy., New Orleans,
LA 70121 504-885-9865.
STEREO COMPONENTS -Write us before you
buy for our low discount price quotes. BTC and
Friends, Box 644, Paramus, N.J. 07652.
SUPER DYNA MK Ill's, for those who appreciate
the sonic differences in power amplifiers- Completely assembled, $225 per amp. Custom
modification available to Mk III owners at S12ó
per amp. These amplifiers must be listened to
through the most transparent speakers to be
fully appreciated. R. B. Bryant, Audio Consultant,
4511 Kelso Court, Woodbridge, Va. 22191,
(703) 590-2568.
AMPEX PR -10
'/z track heads,
71/2-15 ips.
Excellent condition, $475.00. Crown DC -300,
used two months, $450.00. 1203 N.W. 4th
Ave., Gainesville, Florida, 32601. (904) 373-3043.
CANADIANS -DEEP DISCOUNT PRICES. Name
Brand HI -Fi components. All "Canadian Warranty"
protection. No Duty. Send quotation requests to
Cartronics, Box 783, Hazeldean, Ontario.
LOW NOISE RESISTORS-t/4W, 5%, carbon
film for 3.50 each. Fifty of one value for $1.25.
All 5% values from 10
to 3.3M
in stock.
Specifications upon request. 750 postage and
handling charge per order. Deduct 10% on
orders over $50. COMPONENTS CENTER, P.O.
Box 134, N.Y., N.Y. 10038.
AUDIO RESEARCH SYSTEM: Tympani-1-U,
D-75, D-50 fib, SP -2C. System price $2200 or
will sell separately. Cross, 1817 Birch, Richland,
Wash. 99352. (509) 946-5200.
MAGNAPLANAR T-IU, Two Pair, Joe Curcio,
St. College, Pa. 1-814-237-3905.
AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
preamplifier with
one month with
two years -$800.
328 Simonton St.,
NOVEMBER 1973
FOR SALE
FOR SALE
AT LAST -an ultra -high definition record playing
system for the audiophile! Discover far greater
DETAIL and RESOLUTION in your system.
Information available from the DKL LAB, Box
683, Severna Park, Maryland 21146.
WE ARE INFINITY, SERVO -STATIK AND
MONITOR SPECIALISTS, offering components
specifically designed for these speakers. The
and
LAB -TESTED
are
finest
components
MATCHED for the most LIFE -LIKE, uncompromising sound available. For information write the
DKL LAB Box 683, Severna Park, Maryland
21 146.
KLIPSCH
Speaker
HERESY Center Channel
-
$280.00; Sell $150.00. (919) 467-9198.
Cost
DAYTON-WRIGHT XG8-II Speakers,
500 Amp. (919) 467-9198.
Marantz
GRAPHIC EQUALIZER PLANS -$2.50. GREEN
BANK SCIENTIFIC, Box 1008, Green Bank, W. Va.
24944.
AUDIO RESEARCH PRE -AMP SP -1C. $700
plus shipping. Ed Habelman, Route 3, Black River
Falls, Wisconsin 54615 (608) 378-4387.
OWN HAWTHORNE STEREO
now offers the finest in nationally known and
esoteric audio components. We stock Advent,
ESS,
Harmon-Kardon, Infinity,
EPI,
Braun,
Klipsch, McIntosh, Quatre, Rabco, Revox, SAE,
Stax, and Phase Linear among others. Home
trials available as well as complete back-up
service. Mail and phone inquires welcomed.
HAWTHORNE STEREO, 3580 S.E. Hawthorne
Blvd., Portland, Oregon 97214.
PORTLAND'S
ADVENT, CELESTION, CROWN, EPI, JANSZEN,
PHASE LINEAR, REVOX, SANSUI, TECHNICS,
HI -Fl
SHOP,
EVANSVILLE,
IND.
47714.
2 KLH 9 PANELS.
Mint condition. $800.00.
Price Firm. K. Horan, 232 Alverno, Ft. Wayne,
Ind. 46816. (219) 441-5623.
TYPES.
ELECTRONIC CROSSOVERS -ALL
Definitive booklet describes applications; how to
improve all types speaker systems -S 5.00, credited
to first purchase. Huntington Electronics, Box
2009, Huntington, Conn. 06484.
XG-8 Mk II
speakers, latest type. $1,750.00
248-1964 or (203) 393-2600.
DAYTON-WRIGHT
"CTS 'IO" WOOFERS 35-2000 cycles, 4.50
each. Will sell in quantities of 50 or more. Write
P.O. Box AN3-1 "Audio".
AUDIO HISTORY, JUST OFF THE
PRESS 1887-1929 Vintage Radio Book, $4.95.
Deluxe Library Copy, $6.95. 1921-32 Radio
Guide Book New 260p, $3.95. 1973-74 Radios/
Wireless Antiquers Directory, $5.00. 1890 Edison
Electric Light Plaque Replica, $4.95. All postpaid, Ten Day Money Back Guarantee. Order
MIDCO, AM 11, Box 15370, Long Beach, Ca.
RE -LIVE
90815.
Electrostatic
pair. (203)
TAPE RECORDERS
Sony 777 S4 with remote; TEAC A401OS-Buy
both $550.00. PLUS: Viking 88 for sale; Citation
Pre -amp with Citation 3 stereo tuner cabinets;
McIntosh 240. Call Vi. 8-9230 or Ch. 7-9970.
STANTON ELECTROSTATIC HEADPHONES,
year, $75 or highest offer, S. Katkin,
used
662 Hobby Horse La., Milford, Ohio 45150;
(513) 831-2429.
1
THE MONEY SAVER! Write STEREO SPECTRUM,
33139.
NORTHERN N.J.'S FINEST AUDIO STORE, 20
minutes from N.Y.C. Bozak, B&O, Hartley,
Infinity, Magneplanar, Marantz, Phase Linear,
Write or Call
SAE, Thorens,
Quintessence,
UNIVERSITY STORE 57 E. RIDGEWOOD AVE.,
RIDGEWOOD, N.J. 201-447-5700.
INFINITY SERVO -STATIK
I
Rosewood, One
year old, in absolute perfect condition. $ 1500.
(904) 576-3820.
ONE SENNHEISER CONDENSER
104 System. $180.00. A. Yonge,
N E
Seattle, 98105.
.
AUDIO
Buy direct from us, and you
save money with our high volume prices on more than 100
Order from
name brands.
the branch
nearest you
to save time
and money
on
freight.
Chicago, 60611.
PRINTED BOARD DESIGN AND FABRICATION.
Write to P.C.D.S. 1610 Melville Ave., Fairfield,
Ct.
06430.
KLH-9 ELECTROSTATIC SPEAKERS.
Pair
list $ 1395.00. Pair absolutely factory sealed
for $990. New Pioneer SE100/J electrostatic
headphones, $89. Also available: Rabco, Thorens,
Ortofon, Marantz, Revox, Ohm, Soundcraftsmen,
DBX, Microstatic, Quad, Janszen. Park Radio, 202
W. Fayette St., Baltimore, Md. 21201 (301)
727-1134.
MIKE-MKH5228 -21st
Midwest
Wholesale
&
BRAUN 810'S w/ STANDS. Year old. Perfect.
$600. Preston, 152 Hayden Rowe, Hopkinton,
MA 01748.
J.B.L. 12" EXTENDED RANGE SPEAKER Model
D123 without enclosure. Write C. A. Schneider,
1230 -20th St., Rock Island, Ill.
ENGLAND'S LEADING MAIL ORDER AND
DISCOUNT SPECIALIST OFFER: -SME, Tannoy,
B&W, TEAC, Sansui, KEF, Cambridge, Armstrong,
Celestion, Decca, London MK V and Decca Tone arm at very competitive price. Please send for
quotes. Reply by airmail. Shipped immediately.
Freight collect. Southern Audio Services LTD.
@ 43 High Street, Kingston upon Thames. Surrey,
England.
ATTENTION
-A
new
WESTERN NEW YORK AUDIOPHILES
store specializing in personalized, friendly service
is now open. We carry Infinity, RTR, Thorens,
Sony, B&O, Phillips, Harman Kardon, Sherwood,
Dokorder and others. The
Soundcraftsmen,
Stereo Emporium, Inc. 3407 Delaware Ave.
Buffalo New York. 716-874-3372.
SERVICES
I
Box 1818, Miami Beach, FL
Why PaY
retail for hifi?
UNBELIEVABLE SAVINGS on 8 track cartridges.
Latest list 250. Bob Musial, Box 11907-A,
EQUALIZE YOUR TAPE RECORDINGS OR
HI-FI with inexpensive, easy -to -build TEN KNOB
THORENS.
INDUCTORS, MYLAR CAPACITORS, nylon
bobbins, complete networks & raw speakers.
Write for list. Mike Lewis, 3673 W. 113th St.,
Inglewood, Calif., 90303.
DON'T PAY the high mail order prices. Thieves
Warehouse is coming up to your area. Franchises
available. Thieves Warehouse, P.O. Box 8057,
Pensacola, Florida 32505.
HIGH FIDELITY SPEAKERS REPAIRED
AMPHRITE SPEAKERS SERVICE
655 Sixth Avenue, New York 10, N.Y.
21 2-CH 3-4812
BOSTON
MASS.
AREA Authorized -Service
for Panasonic-J.V.C.:Fisher-V.M.-Webcor-Magnavox-Lloyd's-Motorola-Juliette-Ross-York. "Where
the faults go out and the quality goes in." Al's
Radio and TV. 1592 Columbus Ave., Roxbury,
Mass. 02119. (617) 442-8850.
NOW LOWEST PRICES FOR STEREO MASTERS
expertly cut on a Scully lathe with the Westrex
3D stereo cutting system. Stereo: 12''-$33
per side 7"-$14 per side Mono: 12"-$22 per
side 7"-$9 per side. Trutone Records 6411
Bergenwood Ave. North Bergen, N.J. 07047
201-868-9332.
MAIL ORDER DIVISION
Send for our free catalog!
2455b Wisconsin Ave,
Downers Grove, Ill 60515
3309 E. J W Carpenter Frwy,
Irving, Tex 75062
Check
No. 36 on Reader Service Card
SERVICES
THE NEW YORK AUDIO SOCIETY is a hi-fi
club with a comprehensive activities program and
numerous member benefits. Come and be our
guest at one of our meetings and see what we
have to offer. For details write N.Y. Audio Soc.
Dept. A; Box 5889, Grand Central Sta.; N.Y., N.Y.
10017 or call M -Fri.
3900.
10AM-6PM (212) 242-
RECORDS MADE FROM YOUR TAPES Also,
editing and mastering. Send for free brochure.
Nashville Record Productions, Inc., Dept. AM
204 19th Ave., So., Nashville, Tennessee 37203.
RECORDER HEADS brought back to
spec. Wear removed. Brilliant finish. $ 10.00
each. One day service. E. Maher, 5 Evans Place,
Orinda, Calif. 94563.
TAPE
CUSTOM RECORDING SERVICE Tape and disc.
Stereo and mono. Live and copies. Editing.
Masters and pressings. High quality at reasonable
rates. Joseph Giovanelli, Audio Tech Laboratories,
2819 Newkirk Ave., Brooklyn, N.Y.
IN 9-7134.
THE ABSOLUTE SOUND©, a new quarterly
magazine for those seriously interested in the
reproduction of music. Subscribe now and you
will receive Issues 1 through 3, a cornucopia
that includes detailed and subjective component
Dayton -Wright
reviews (e.g., Magneplanars,
electrostatics; IMF speakers; Levinson electronics); essays (Mike Wright and Jon Dahlquist
on speaker design; Arthur Aaron on Stokowski
and the American Symphony Orchestra); reviews
of the best -sounding records and tapes; reader
surveys in which our readers describe their
biggest lemons and other things. The cost?
S8 annually; four issues. The Absolute Sound,
Box 115N, Sea Cliff, N.Y. 11579.
109
NOVEMBER 1973
www.americanradiohistory.com
AmericanRadioHistory.Com
HUGE GS
tl
Sp'
pU S
oFA,1N
BRAND
COMPONENIs
BUSINESS OPPORTUNITIES
EQUIPMENT WANTED
MAILORDER MILLIONAIRE helps beginners
make $500 weekly. Free report reveals secret
plan! Executive (1Q10). 333 N. Michigan,
MARANTZ MODEL 6 Stereo adapter, Marantz
Model
Mono Preamps. Marantz Electronic
Crossovers. State condition and price. Box AN3-2.
Chicago 60601.
McINTOSH MI -200 power amplifier. State price
and condition in first communication. K. Horan,
232 Alverno, Ft. Wayne, Ind. 46816 (219)
SIEREO
Agency Details!! $ 1,000.00
Monthly Possible. Master-4, Drawer 77009,
Atlanta, Georgia 30309.
DISCOUNTS
YOUR IDEAS ARE WORTH BIG MONEY. Exciting
new book tells secrets. Free details. Neotek (AA),
19309 Revere, Detroit, MI 48234.
FREE
ON NATIONALLY ADVERTISED
TURNTABLES
COMPACTS
AMPLIFIERS
CARTRIDGES
HELP WANTED
RECEIVERS
TAPE RECORDERS
Wholesale Prices! Audio Warehouse Sales,
One of the Capitoli largest stereo wholesalers will fill and deliver all your mail
orders promptly in factory sealed cartons,
at prices that will amaze you.
Write for quote on Famous Brand,
Stereo Components. We guarantee
satisfaction.
WAREHOUSE
AREHOUSKAVÉEÑE.
D.C. 20002
WASHINGTON,
832-1616
(202)
Check No. 13 on Reader Service Card
SER VICES
LOW PRICED PROFESSIONAL QUALITY Location Recording in Illinois and Indiana. Send
for free price information. N. Beer, 515 Fourth
Ave., Ottawa, III. 61350.
TYPE YOUR OWN SLIDE So easy,
and economical for educational and
For free sample write Radio Mat
444 N. Peninsula Drive, Daytona
convenient
advertising.
Slide Co.,
Beach, Fla.
32018.
HAVING TROUBLE GETTING A GOOD DEMO
AT A GOOD PRICE? Trutone Records cuts the
finest quality demos available, and you'll be
surprised at our low, low prices. STUDIO DISCOUNT AVAILABLE. Request brochure. P.S.
We also do complete record production. 6411
Bergenwood Avenue, North Bergen, N.J. 07047
(201) 868-9332.
BUSINESS OPPORTUNITIES
$25.00 HUNDRED stuffing envelopes. Immediate
earnings. Beginner's Kit. $1.00 (refundable).
Lewcard. A392 DU, Brea, California 92621.
MONEY
AVAILABLE NOW! Both Personal,
Business Uses
$500 to Millions. Finance
Anything
Get Rich Techniques
Thousands Actual Sources. Free Details. AIDS, Box
725-AUD, Holland, Michigan 49423.
.
.
.
.
A UTO
ACCESSORIES
DECALS -Wildlife,
dogs, horses.
Send 80
stamp for free folder. Dealer inquiries invited.
A.D. Tyler, A.D. 1301 Methuen St., Dracut,
Mass. 01826.
SPEAKERS-Acoustically designed and built
for Ya -3i cost of factory speaker systems.
SAVARD, 600 East Roosevelt Box 360, Baton
Rouge, LA. 70802.
MISCELLANEOUS
PORTABLE WATER PURIFIER -Purifies naturally
with activated oxygen, the most effective water
purifier agent known. Helps protect health by
killing disease producing bacteria and removing
toxic impurities. MADE IN U.S.A. For more
information write: PRINCE STERLING, 323
GARCES DRIVE, SAN FRANCISCO, CALIF. 94132.
MULTI -CHANNEL TAPES Processed from YOUR
Mono Records Tapes. Demo Tape $ 1.50. R. R.
Faulkner, Box 26, Redondo Beach, Calif. 90277.
.
SERIOUS RECORDISTS NEEDED Excellent
remuneration. We train and equip. Modest
investment required. Write Box 278, Englewood,
Ohio 45322.
HI-FIDELITY
AUDIO
3310 NEW
Collection
.
.
.
EQUIPMENT WANTED
441-5623.
.
WANTED: VICTOR ORTHOPHONIC
REPRODUCER in perfect condition. Victor 78's:
7292/3 Henry VIII Suite (Saint-Saens) Damrosch,
Nat. Sym. All types changeable needles. Particularly Victor Tungsten. Chorus of Dervishes
(Beethoven) Heifetz, Vic. 64759 (or double).
Vic Red Seal (double-faced) cat., 1919, 20, 21.
Dominic McBride, 785 Minna St., San Francisco,
.
Calif. 94103.
WANTED:
SG -520E,
McINTOSH
33-7-1421,
MARANTZ
model 7c, 8B; JBL,
SE-400SE,
Sovereign
(S8R);
C-22, MC -275. Kazuo Takishima,
2 cho -me, Takashima-daira, Itabashiku, Tokyo, 175 Japan.
AUDIO
Price?
I
BACK -ISSUES WANTED
1968/73.
Condition? Dates? Cone, 775 South
GOVERNMENT SURPLUS
JEEPS Typically From $53.90.
Trucks from
$78.40... Boats, Typewriters, Knives, Airplanes,
Clothing, Multimeters, Oscilloscopes, Transceivers,
Photographic Electronics Equipment, Wide Variety
Condition 100,000 Bid Bargains Direct from
Government
Nationwide.
Complete.
Sales
Directory and Surplus Catalog $1.00 (Deductible
on Orders From Separate Included Catalog).
Surplus Service, Box 820-AUD Holland, Michigan
.
WANTED: CROWN, R.O.M. Write Jim Hollinger,
Galen Hall Rd., Rt. #3, Wernersville, Pa. 19565.
KLIPSCHORNS, USED. State style and condition. C. C. Bonsell, 2201 Martin Ave., Dayton,
MANUALS FOR
GOV'T.
WANT ANGEL TAPE *3634, Mahler 2nd.
Klemperer/Philharmonica.
D.
Karsch,
1010
Fifth Avenue, New York City 10028. (212744-2827 after 6 PM.)
LOOKING FOR AN AMPEX MICRO 155 which
came out last year (1 972 model). Anyone owning
one and willing to sell -must be in excellent
shape -please call me. Willing to pay fair price
for unit. A. Licata, 85 Livingston St., Apt. 56,
Brooklyn, N.Y. 11207.
WANT MERCURY RECORD *90449. Hanson
3rd Symphony. Advise price/condition. D. Karsch,
1010 Fifth Avenue, New York City 10028.
WANTED!
LARGE ELECTRO -VOICE Patrician
Model IV or 600. Also E-V Georgian. J.C. Lucken,
1635 W. Onondaga St., Syracuse, N.Y. 13204.
1-315-479-5783.
WANTED TO
PURCHASE: Material on Jane
Powell, either musical selections or spoken
interviews from television, night clubs, etc.
D.B., P.O. Box 7324, Atlanta, Ga. 30309.
110
Radios.
7218
JEEPS, TRUCKS, Cars From $31.50.
Airplanes,
Typewriters,
Clothing,
Multimeters,
Transceivers,
Oscilloscopes,
Photographic,
Electronics Equipment
100,000 Surplus
Bid Bargains Direct From Government Nationwide
Typically Low as 20 on Dollar! Complete Sales
Directory and Surplus Catalog 81.00 (Deductible
First $10 Order From Included Catalog). U.S.
Surplus Disposal, 2200 Fuller 601B -AUD, Ann
Arbor, Michigan 48105.
.
.
.
INSTRUCTION
&
ED UCA TIO N
BIBLE
Degrees -Correspondence -Fundamental
Bible Seminary. P.O. Box 942, Elk City, Oklahoma 73644.
LOGIC trainers catalogs 500. UTI, POB 252,
Waldwick, N.J. 07463.
TAPE RECORDING COURSE: Taught by studio
engineers. Free information, NNA, Box 721E,
Rye, New York 10580.
EARN
COLLEGE
DEGREES
AT HOME.
Many subjects. Ministerial studies, high school
equivalency diploma. Florida State Christian
University, Post Office Box 1674, Fort Lauderdale,
Florida, 33302.
RECORDS
CATALOGS Broadcasts, soundtracks. Personalities of Thirties, Forties, Box 225, New York, N.Y.
10028.
RARE Deleted Motion
Show Albums. Steiner,
man, Young, Bernstein,
BEST." Send 250 for
ReCollections, P.O. Box
Jersey 07204.
AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
SURPLUS
Test Sets, Scopes. List 500. BOOKS,
Roanne Drive, Washington, D.C. 20021.
Ohio 45414.
WANTED FOR CONSIDERATION and critical
evaluation -Custom engineered audio components,
amplifiers and preamplifiers, etc. I. David, 157
Coyne Pl., Belford, N.J. 07718.
.
49423.
.
CASH FOR YOUR unwanted stereo LP's and
reel to reel tapes. Record House, Hillburn, New
York 10931.
.
IMPORT-EXPORT OPPORTUNITY. Profitable
world-wide, mail order business from home,
without capital or travel abroad. We ship plan
for no risk examination. Experience unnecessary.
Free report. Mellinger, Dept. G 1539, Woodland
Hills, California 91364.
1
Picture Soundtrack and
North, Goldsmith, WaxStyne, etc. "ONLY THE
new quality catalog to
197, Roselle Park, New
NOVEMBER 1973
PHOTOGRAPHY
RECORDS
SHOW ALBUMS -Rare. Out of Print Lp's. Free
Recordings
large
list.
Broadway/Hollywood
Georgetown, Conn. 06829.
FILM -STAGE SOUNDTRACKS. Large free list.
A. Lutsky, Box 7342, Miami, Fla. 33155.
OLDIES -45 RPM Original hits. Catalog 50C
C&S Record Sales, Box 197, Wampsville, N.Y.
13163.
RARE
RECORDS -Send
Bronx, N.Y. 10469.
wants.
Box
410,
LP
CATALOG -Deleted Soundtracks,
Shows, Nostalgia. A. Roseman, P.O. Box 16083,
Phila., Pa. 19114.
FREE
THREE GREAT JAZZ ALBUMS! Write: Bountiful
Records, 12311-A Gratiot, Detroit, Michigan
48205.
200 -PAGE CATALOG. 1,400 New Stereo
Recordings. Renaissance, Baroque, Classical,
Romantic, Modern Music. Not sold in stores.
Not listed in Schwann's. Highest quality! Budget
label prices! Available only by mail. MUSICAL
HERITAGE SOCIETY, Box 932 AU, New York,
FREE
N.Y. 10023.
& Jazz
SOUNDTRACKS-O.C. -Personalities
Want lists to: Theo's Records, P.O. Box 4994,
Panorama City, Ca. 91412.
RECORDS
PILITA CORRALES -Winner 1973 International
Music Festival -Tokyo sings about "LOVE", Stereo
$6.00 AIRMAILED!! Record -Handicraft catalog
$ 1.00
(Refundable). ARABELL CO., PITOGO,
QUEZON E-327, PHILIPPINES.
RECORDS -soundtracks, show, cut-outs. Send
wants -we'll quote. Lesco, 2205 Marylane,
Broomall, Pa. 19008.
OPERAS, OPERETTAS, OPERATIC RECITALS.
Lieder, Chansons, Scandinavian, Spanish vocals,
piano, etc. Many rare items from private collection.
SIERLE, 80 Central Park West, NYC 10023.
SOUNDTRACKS, original casts and personality
recordings -Many hard-to -find titles at reasonable
prices. Send for large, new catalog free. Robert
Hiott, Box 471, Miami, Florida 33144.
SOUND -TRACK SUPER SPECIALS MASTER OF
WORLD -MONO -$2.99 ONE EYED JACKS LIMITED -SHIPPING
SUPPLY
MONO -$5.99
EACH
RECORD -.15
1ST
CHARGES -.50
ADDITIONAL. INTERESTING RECORD SHOP,
220 WEST 23RD ST., N.Y., N.Y., 10011.
THE
SOUNDTRACK SPECIAL-"Let's Make Love",
"Milanese Story", "King Rat", "Dr. Goldfoot",
"7th Dawn". (All five mono). Plus "Ted, Alice,
etc.", "Cactus Flower". (Both stereo). All 7 mint sealed -$39.95 + $3.00 U.S. Postage-Handling.
Money orders only to: L & K, 3082 N. Elston,
Chicago, III. 60618.
-
choice film/stage/
SALE
LP's. Non -dealer prices. Free list.
5424 Carlton Ave., Oakland, Ca.
LIQUIDATION
personality
Nelson,
94618.
SOUNDTRACKS -Lowest Prices. Catalog: 25C.
320 Rare Titles. 1600 LP's, Write: AUDI, Box
715, Florissant, Mo. 63033.
SOUNDTRACK
(RARE
GAZETTE
NEWSLETTER)-Hundreds of soundtracks on
Free
Sample.
prices!
sale monthly -lowest
RTSA, 1111 S. Benito Avenue, Suite F, Alhambra,
California 91803.
MUSIC
LARGEST SELECTION of rare
mint soundtracks -Band of Angels, Destination
Moon, Etc. Free catalog. Old Record Warehouse
5516 N. Kimball, Chicago, III. 60625.
MIDWEST'S
AUDIO
12 EXPOSURE ROLL KODACOLOR
developed -printed jumbo, $1.50. Capri
Box 831, Laredo, Texas 78040.
FILM
Color,
MUSIC
PAIA HAS...
synthesizer
KITS
BRAZILIAN -Latest hits from Brazil. Not Sergio
Mendes. Not available in the U.S. Write Braziliansound, Box 1280, Bellaire, Tx. 77401.
RARE ROMANTIC PIANO SCORES-Moscheles,
Henselt, Herz, Litolff, Scharwenka, Scriabin,
etc. Free catalog. MUSIC TREASURE PUBLICATIONS, Box 127, Highbridge Station, Bronx,
New York 10452.
MODELS PRICED FROM $139
TAPE RECORDINGS
RENT 4 -TRACK open reel tapes -all major
labels, 3,000 different. Free brochure. Stereo Parti, 55 St. James Drive, Santa Rosa, Cal.
FREE
BROCHURE AND CATALOG
OF THE COMPLETE PAIA LINE
95401.
KENNEDY/TIPPIT/OSWALD MURDERS! Actual
episodes & police recordings! Reels/cassettes:
Foxbury, Rico -Rivera,
$ 10.
Majestic,
9651
California.
NEW TAPE EXCHANGE CLUB. All Formats.
Details 25C. Bob Musial. Box 11907-A, Chicago,
III.
60611.
PAIA ELECTRONICS
BOX M14359, OKLAHOMA CITY, OK 73114
Check No. 39 on Reader Service Card
RADIO PROGRAMS
TAPE RECORDINGS
OLD Radio Show Monthly Special Club-TBOR,
Box 1692A, F.D.R. Station, New York 10022.
BETTER BY SHEARING.
Replaces razor. Specify 1/4" or cassette, S16.95;
with attached splicing tape mechanism, $24.95.
Details-NRPA, Box 289, McLean, Va. 22101.
SPLICE FASTER
EVERYTHING ON OPEN REEL! Thousands of
prerecorded classical/popular tapes. Latest releases. Discounts. 96 -page catalogue $ 1. Barclay -Crocker, Room 333C, 11 Stone Street, NYC
10004.
8 -TRACK TAPES $1.75
By joining Star Tape Club. Buy as many as you
want or none. No obligation. Big name hit tapes.
Rock, Soul, Popular, Best of, Religious, Bluegrass, Classical, Country, Jazz, also Party. Join
direct from this ad. Send $4.00 to:
STAR ENTERPRISES
35 -AM Woodcrest Ave., Dayton, 0. 45405
OPERATAPES, RECORDS, "Live" performances,
broadcast. Free catalog. Hathaway, 49A Merbrook,
Merion, Pa. 19066.
RENT ANY CASSETTE or Open Reel Prerecorded
tape. All Labels. Catalog 75C. Tape & Time,
P.O. Box 740, Hopkins, Minn. 55343.
RADIO PROGRAMS
REMEMBER RADIO? On cassettes or reels. Amos
& Andy, Inner Sanctum, Jack Armstrong, Fred
Allen,
Love a Mystery, Your Hit Parade, Grand
Ole Opry, All your Favorites live again. High
quality, low prices. Catalog only 50C Remember
Radio, Inc., 2513-B; Norman, Okla. 73069.
NOSTALGIA
RADIO
Private collection.
Delaware 19804.
PROGRAMS traded.
3226, Newport,
Drawer
Large selection,
OLD RADIO PROGRAMS
sample tape and catalog S1.00. Audio Antiques
Box 6651, Cleveland, Ohio 44101.
THOUSANDS
OF
RADIO
OLD
COMEDIES,
Dramas, Band Remotes, Mysteries, etc., $6.00
for 6 Hour Reels. Catalogue: $ 1.00 (Refundable).
RADIOVOX 1756,
Cassettes also available.
Washtenaw, Ypsilanti, Michigan 48197.
REAL ESTATE
IDEAL 5 -ACRE RANCH. Lake Conchas, New
Mexico, $4,975. No Down. No Interest. $30/mo.
Investment. Free
Good
Vacation Paradise.
Ranchos, Box 2006JF Alameda,
Brochure.
California 94501.
SONGWRITERS
GET IN ON THE MONEY to be had in the booming song and music world as a lyric writer.
Co -write with me on a 50-50 basis. Publishers
promotion.
Recording
guaranteed.
contract
Send lyrics with stamp: Paul Jackson, Rt. 9,
Box 292-cr, Athens, Ala. 35611.
INVENTIONS WANTED
PROSECUTE YOUR OWN Patent Application.
All Material Necessary -Write: Inventors Service,
Box 3574, Washington, D.C. 20007.
I
PLANS
&
KITS
DIGITAL CLOCK KIT. Six large green readouts,
RADIO PROGRAMS ON TAPE
Huge catalog! Hour samples!! $ 1.24, refundable!! AM Treasures, Box 192M, Babylon, N.Y.
11702.
Mostek chip, drilled P.C. board, all electronics,
$45.00. Solid Mahogany
and instructions
decorators cabinet $9.50. Prices include shipping.
Digi-Tel Electronics, P.O. Box 6585B, Toledo,
Ohio 43612.
RADIO PROGRAMS. CATALOGUE OF THOUSANDS: $ 1.00 (Refundable). THE RADIO VAULT.
BOX 9032 -TV. WYOMING, MICHIGAN. 49509.
WAVEFORM Generator Kit $10.00. Stereo
Multiplex Kit S19.95. Free Kit Catalog. Photolume
Corp., Box 139, N.Y., N.Y. 10016.
RADIO MEMORIES. Custom recorded reels and
cassettes. Professional quality equipment assures
best sound, but at prices YOU can afford. Large
catalog and supplement $1.00 (refundable). 1033
Gypsum, Salina, Kansas 67401.
PYROTECHNICAL chemicals,
1930-1962
casings, tools,
literature.
Giant, illustrated
catalogue/handbook includes formulas, instructions -50E, with samples -S1.00. Westech,
Box 593, Logan, Utah 84321.
supplies,
fuse,
111
NOVEMBER 1973
www.americanradiohistory.com
AmericanRadioHistory.Com
'.."'----_-
sor+r
www.americanradiohistory.com
AmericanRadioHistory.Com
And then there was music.
And then came Sony tape recorders
to capture the words and music
with perfect fidelity. Right from the
start. Sony has always been first with
the best, the newest and the broadest
selection of tape recording equipment in the world. Sony tape
recorders, Sony accessories, Sony
microphones, Sony recording tape.
We could go on and on and on.
We are.
SONY Ask anyone.
Check No. 63 on Reader Service Card
L
01973 Superscope, Inc.,
hope dealer Send
subject to change without notice. Consult the Yellow Pages for your nearest Supen
8142 Vineland Ave., Sun Valley, Calif. 91352. Prices and models
or free catalog.
2
ISCRETE
makes
i
ihi
Switch.
4 -CHANNEL
E
'
s
irresistible
"
The KENWOOD
`Two -Four Receivers give
you all tie great new 4 -channel sounds,
plus the finest 2 -channel reproduction!
A unique `strapping' circuit more than doubles the
RMS output per channel when you turn that simple
sw"etch from 4- to 2-channel mode. For example, 17 watts x 4
(RMS Power at 8 ohms, 20-20k Hz) automatically becomes
40 watts x 2 for the KR -6340. Just one of the many features
that make switching to 4 -channel with KENWOOD
KR -6340
completely irresistible:
Bur,lt-on SQ, RM, Discrete, plus Optional CD -4 Plug -In
Adapter Full 4 -Channel Cortrcl Center Direct Coupling
for M!ninal Distortion Exclusive DSD in the MPX for
Unexcelled Channel Separatio- And much, much more!
For complete specifications write
..
Broadway, Gardena, Calif. 9024
72-02 =fifty-first Ave., Woodside, N.Y. 11377
In Canada: Magnasonic Canada l.td.
[email protected] So.
Check No. 31 on (Reader Service Card
KR -5340
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