A Novel Acoustic Feedback Loudspeaker

The
Authoritative Magazine About High Fidelity ® A
Evaluating an FM Tuner
A Novel Acoustic Feedback Loudspeaker
A Tone-bursi Generalor, Part
New Receivers & Tuners
www.americanradiohistory.com
III
Lise it any way you wish;
the Scott 433 performs better
than any other tuner
you can own.
card into a slot and the exclusive
Scott Digital Frequency Synthesizer automatically tunes to the
center of the channel you select.
The tuning error is so small it is
actually less than one-third that
allowed broadcast stations by the
FCC. The 433 tuner comes with
program cards for every one of the
100 FM
channels
available
in the U.S.
The Scott 433 Digital Frequency
Synthesizer FM Stereo Tuner gets
you about as dose to the actual
broadcast as today's technology
will permit and with greater convenience than ever before.
Using such space age electronic
circuitry as a phase locked loop,
a varactor tuned RF section and a
quartz crystal reference standard,
Scott engineers have
produced the
first dramatically
superior tuner
since they pioneered
the silver plated 1h'1 tuner in 1965.
You no longer turn knobs or read
tuning dials. You insert a program
In addition to automatic card programming,
you can scan the entire FM band
for either mono or stereo stations,
or manually tune to any station
of interest by pushing a button.
The large digital display tells you
c3
accurately what
frequency is
being received,
and you can
read it from
across the room.
In short, the Scott 433 Digital
Frequency Synthesizer FM Stereo
Tuner looks and performs better
than any tuner you have ever seen
regardless of price. Matched set
indudes the 490 Integrated Stereo
Control Amplifier with 75 watts
per channel continuous power
RMS into 8 ohms. Model 490
amplifier. $349.90. Or you can
play the 433 tuner through any
high quality stereo amplifier.
Model 433 Digital Frequency Synthesizer FM Stereo Tunen $549.90.
See your Scott dealer or write
for full information.
SCOTT®where
innovation
i's
a tradí
H.H. Scott, Inc., 111 Powdermif Road
Maynard, Massachusetts 01754
Check No. 100 on Reader Service Card
www.americanradiohistory.com
TEAC's AN-80 and AN-180
Noise -Reduction Units:
/.
/1/,
If Rossini
were alive today,
he would set
their specs
to music.
77
/1,l/7,, /,./
1///7/
///;,/
4Í /f inr/474.
Rossini once made this boast and could
probably have delivered. But a recording of
the music on the best of today's cassette or
reel-to-reel machines with their inherent noise
and hiss could never capture the clean, crisp sound of the Rossini laundry list.
With the introduction of TEAC's AN -180 Dolby* Noise -Reduction Unit, Rossini's Laundry Largo and just
about anything else you record will have the same brilliance and luster as the original.
Our Dolby circuit removes machine and tape noise with such thoroughness that there is a signalto-noise ratio improvement of 3dB at 600 Hz, rising to 5dB at 1000 Hz and 10dB at 4K Hz and above.
Because we manufacture the ICs used in our Dolby circuit to extremely tight tolerances, ours operates
at distortion levels of less than .3%-lower than many competitive units. So you see there is no question
that you should have a TEAC Dolby Noise Reduction Unit.
We designed the deluxe AN -180 not only to Dolbyize fine decks, but to afford them features they
might be missing.
It's actually a simultaneous record -playback control
center with its own record and playback amps.
It has built-in mike and line preamps
AN -180
that maintain mixing capability, or add
this capability to recorders not so
endowed. It has large professional -type
VU meters for Dolby level setting as well
as record/playback level indicators.
AN -180 also incorporates such features
as an internal 400 Hz, 100 My oscillator
level controls, source/tape monitoring and a
multiplex interference filter.
Even without Rossini to write a setting for the AN -180
specs, they make such beautiful music.
Frequency Response, 20-15,000 Hz -1.5dB
Signal to Noise Ratio, better than 65dB
Increased SN Ratio, 10dB at 10,000 Hz
Harmonic Distortion, below 0.3%
Channel Separation, better than 55dB
If you just need the best no-nonsense Dolby with none of the
frills, ask your dealer about the TEAC AN -80.
TE AC
'Colby
TEAC Corporation of America, 7733 Telegraph Road, Montebello, California 90640
Nishi-shinjuku, Shinjuku-ku, Tokyo, Japan
TEAC EUROPE N.V., Kabelweg 45-47, Amsterdam -W.2, Holland
TEAC Corporation, 1-8-1
In Canada: White Electronic Development Corp., Ltd., Toronto
Check No. 29 on Reader Service Card
www.americanradiohistory.com
is a
trade mark of Dolby Laboratories. Inc.
AU
Io
Successor to
JANUARY 1972
Jay
Editor
Publisher
Edward Tatnall Canby
Marketing Director
SCINTREX INC.
Tonawanda, N. Y. 14150
Assistant Editor
John Kwasizur
Cover Design
S. L.
Rowena Kendall
Jean Davis
Bert Whyte
Designer
Subscription Manager
L.
Sanford
L.
Cahn
Mary Anne Collins
Advertising Production
1
Weingarten
FEATURE ARTICLES
18 How to Evaluate the Stereo FM tuner Daniel
26 Men of Hi-Fi: The Perfect FM Tuner
32 The Acoustic Feedback Loudspeaker System
42 IC Tone Burst Generator, Part Ill
R.
von Recklinghausen
Harry E. Maynard
Curtiss R. Schafer
Walter G. Jung
GUIDE TO TUNERS AND RECEIVERS
38 New Receivers
40 Four-Channel Equipment
41
New Tuners
EQUIPMENT REVIEWS
48 Crown Stereo Console
48 Crown Stereo Power Amplifier
IC -150
D-150
Model 2+2
Model 1218
58 Telex Tape Recorder
61 Dual Automatic Turntable
62 Acoustic Research Loudspeaker
AR -6
THE WORKBENCH
64 Heath VOM
66 EICO Capacitor Bridge
Model IM -105
Model 905
RECORD REVIEWS
68
72
76
78
Edward Tatnall Canby
Edward Tatnall Canby
Sherwood L. Weingarten
Martha Sanders Gilmore
Classical Record Reviews
Canby's Capsules
Weingarten Looks At ..
Jazz and Blues
AUDIO IN GENERAL
4 Coming in February
10
12
4 Audioclinic Joseph Giovanelli
6 Tape Guide Herman Burstein
16
8 What's New in Audio
79
82 Advertising
Dear Editor ..
Behind the Scenes Bert Whyte
Editor's Review
Classified Advertising
Index
.
AUDIO (title registered U.S. Pat. Off.) is published by North American Publishing Co.. I.J. Borowsky,
President: Frank Nemeyer and Roger Damio, Vice Presidents; R. Kenneth Baxter, Production Director;
Nate Rosenblatt, Promotion Director: Mary Claffey, Circulation Director, Subscription rates-U.S.
Possessions, Canada, and Mexico, $5.00 for one year; $9.00 for two years; all other countries, $8.00 per
year. Printed in U.S.A. at Columbus, Ohio. All rights reserved. Entire contents copyrighted 1971 by North
American Publishing Co. Second class postage paid at Philadelphia, Pa., and additional mailing office.
REGIONAL SALES OFFICES: Jay L. Butler and Sanford L. Cahn. 41 East 42nd St., New York.
Telephone (212) 687-8924
Jay Martin 15010 Ventura Blvd Sherman Oaks. Calif 91403' (213) 981-7852.
REPRESENTATIVES:
United Kingdom:
House. Fulwood Place. London. W.0
Export Agents
ELPA MARKETING
INDUSTRIES, INC.
Butler
Contributing Editors
Herman Burstein
Leonard Feldman
Richard Freed
Joseph Giovanelli
C. G. McProud
Harry E. Maynard
Alexander Rosner
Eugene Pitts
SHARPE AUDIO
DIVISION
Est. 1911
Vol. 56, No.
George W. Tillett
Associate Editor
all you need in
headphones is
expert engineering,
the best materials,
great styling,
fine craftsmanship
and not a trace of
sound distortion.
That's all!
That's what Sharpe
Stereophones are all
about. We make them
in the best possible
way so that you get the
best possible
listening. Not just
regular listening.
The Sharpe kind of
listening. The two
are worlds apart.
That's because
Sharpe units a -e true
scientific instruments.
That's where we leave
the others behind.
We care all the way
from research to
delivery to you.
There's a Sharpe
model for every
kind of music lover
and for every bjdget.
Models that are
guaranteed for life,
listed top-rated, make
best introductory or
advanced listening
buys. For your
nearest dealer and
literature, check
the reader
service card.
RAM,
N Y.
10017:
Overseas Newspapers (Agencies) Limited. Cromwell
'Telephone 01-242 0661 'Cables: WESNEWS London
Continental Europe: John Ashcraft 12 Bear St.. Leicester Square. London W.C.2. England
Tel 930-0525 For Benelux 8 Germany: W. J M Sanders. Mgr. Herengracht 365. Amsterdam. Holland.
Tel 24 09.08. Japan: Japan Printing News Co Ltd No. 13. 2 Chome Ginza-Higasi. Chuo-kú Tokyo,
1
PS4.
Japan Phone 541-5795
New Hyce Park.
N. Y. 11040
AUDIO Editorial and Publishing Offices, 134 N. 13th St., Philadelphia, Pa. 19107
Postmaster: Send Form 3579 to the above address
Check No.
1
on Reader Service Card
channel...
if you go for f
you don't have to go for broke
Buy yourself a miracle for as little as $209.95. That's all
it takes to get your conventional two -channel stereo to do
anything any total four -channel receiver and control center
can do, now or in the future.
The Sansui QS500 and QS100 converters are complete
Four-Channel Synthesizer -Decoder -Rear -Amplifier -and Control -Center combinations that transform standard two channel stereo totally. The only other equipment you need
is another pair of speakers.
You can decode any compatibly matrixed four -channel
broadcasts or recordings and reproduce them in four authentic channels. You can detect the ambient signals
present in most two -channel recordings or broadcasts and
propagate them through the rear channels. In Sansui matrixing, the exclusive phase -shift technique prevents the cancellation of some signals and the change in location of
others that occur in many matrixing systems. And the
exclusive phase modulators restore the effect of the live
sound field.
You can plug in a four -channel reel-to-reel or cartridge
deck or any other discrete source. In the future if you
you can add any adaptor, decoder or what should have to
have -you for any four -channel system for disc or broadcast
that anyone's even hinted at. And a full complement of
streamlined controls lets you select any function or make
any adjustment quickly and positively.
An alternate four -channel miracle -maker is the modest
but well -endowed QS100, with total IHF music power of 50
watts (continuous power per channel of 18 watts at 4 ohms
and 15 watts at 8 ohms). In a walnut cabinet, it sells for
$209.95.
-
-
COPYPIOMi Br SAMS.
The QS500 features three balance controls for front -rear
and left -right, separate positions for decoding and synthesizing, two -channel and four -channel tape monitors, electrical
rotation of speaker output, alternate -pair speaker selection,
and four VU meters. Total IHF power for the rear speakers
is 120 watts (continuous power per channel is 40 watts at
4 ohms, 33 watts at 8 ohms), with TH or IM distortion below
0.5% over a power bandwidth of 20 to 40,000 Hz. In its own
walnut cabinet, the QS500 sells for $279.95.
Sitre_s-ziL-2
SANSUI ELECTRONICS CORP.
Woodside, New York 11377 Gardena, California 90274
SANSUI ELECTRIC CO., LTD., Tokyo, Japan Sansui Audio Europe
Check No.
2 on Reader
Service Card
www.americanradiohistory.com
S.
A., Antwe-p, Belgium
oin9
c.oado
February
SPECIAL
AMPLIFIER
ISSUE
Amplifier Design
Buyers Guide to
the new Amplifiers
The Measurement of Loudness
by Harry Olson
Equipment Reviews
will include:
Wharfedale W -70E loudspeaker
Sony 130 amplifier
PLUS
1
Record and Tape Reviews and all
the regular features.
Au
Evaluating an FM Tuner
Novel Acoustic Feedback Loudspeaker
A
Tone -burst Generator, Part
ill
New Receivers & liners
About the Cover: Digital readout
becoming quite popular with
the more expensive tuners and
our cover shows a view of the
Sherwood SEL -300 reviewed recently. Other digital tuners are
the Scott 433, the SAE Mk VI,
and the Mikado QS-with several
others hidden in the labs.
is
Joseph Giovanelli
l
FM Reception
and Master Antennas
Q. I often listen to FM in my apartment, which is fairly close to several FM
stations. I have tried several coupling
devices in order to use the apartment
building's roof-top TV antenna, which
only resulted in poor reception for both
the FM and TV sets, no matter what I
did.
by Robert Carver
A
Audioclinic
I am forced to use a T-shaped arrangement which I stretch out on the wall
behind my tuner. This looks awful and
does not give satisfactory results. The
same is true of an adjustable TV
dipole (rabbit ears) which I tried.
Nowhere have I read or heard of an
FM antenna for people who cannot put
up a roof-top installation or project
something from a window because of
apartment house rules.
Do you know of an adjustable indoor
table model which is beyond the dipole
stage and specifically designed for FM?Claudia Grill, Palo Alto, Calif.
A. Unfortunately, no break-throughs
have come along in terms of indoor
antennas. Fortunately, however, the
common dipole does do a reasonably
good job for enough people that FM
listening is worthwhile to them, but I
do realize that not every one will be
lucky.
There are rabbit -ear antennas which
in addition to having a length adjustment for each element, also provide a
system for changing the phase relationships between the two sections. Such
antennas sometimes bring about improved reception.
I judge that your master system was
not designed to receive FM stations.
Such an installation is often set up to
reject all but the TV channels. If enough
tenants in your building complain,
perhaps the antenna system could be
redesigned to include the FM band.
On the chance that your master
antenna does include provisions for FM
reception, the following information
may be useful.
Master antenna systems are usually
75 ohm installations. Your FM and TV
NASTER
ANA
MT
I
TTEO
I
MTENNA
RNINALS
I
V
equipment is, in all likelihood, only
equipped for 300 ohm antennas. On
top of all this, the master antenna uses
unbalanced coaxial line, while your
equipment requires a balanced input
circuit. To overcome all of this you
need to use a transformer which is 75
ohms to 300 ohms. You will also need a
2 -set coupler which is designed to interconnect the FM set, TV set and transformer. The connections are shown in
Fig.
In addition, instructions are
usually provided with both the transformer and the coupler.
By the way, the newer variety of
couplers are so made that it is no longer
necessary to strip the insulation of the
300 ohm twin lead. The screws which
secure the wire to the coupler are so
made as to cut into the insulation and
make firm contact with the conductors.
Oxide Deposits
1
Q. I have a problem with oxide deposits on the record/playback head I
clean the head lubricate it, and within
four to five hours of use there is oxide
visible on the head and there is a noticeable high frequency loss. The pressure
pads don't seem to be excessively strong.
Would changing tape be a solution to my
problem? Is this kind of wear harmful
to tapes over a period of time?-Steven
R. Wagner, Augusta, Ga.
A. All tapes deposit oxide on the
heads (with the exceptions of some
special coated tapes); depending on the
particular tape machines with which
the tapes are used, some may do so
more than others. Therefore it is worthwhile following up your thought of
trying various brands of tape, particularly those of well-known, reputable
manufacturers. If they all deposit excessive oxide, your pressure pads may
be at fault and should be checked.
Does your machine have a tape lifter
to space the tape away from the heads
during rapid wind? If not, this may be
the cause of your problem. Then try
to wind the tape directly from reel to
reel, and not past the heads; or insert
a piece of celluloid between the tape
and the heads during rapid wind.
Rapid oxide wear on a frequently
used reel of tape is apt to harm the
tapes and the heads.
TO TV
ANTENNA
DOT
ERNINAl3
30011
THIN LEAD
Fig. 1-Interconnection of TV, FM &
master antenna.
4
AUDIO
www.americanradiohistory.com
.
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 selfaddressed envelope,
OUR 25th YEAR
JANUARY 1972
it really
comes aiwe...
It would be silly to ask if you dig real live sound. Of course you do. The same holds true for
for things that are really made, and really perform.
quality
-
Our objective in developing the B-301 (Tempo 1) was to give you the best, most lifelike sound
obtainable, in a well -engineered, well -constructed bookshelf system. The fact that performance
fully met expectations, and that we could furnish full-fledged 3OZAK construction quality for a
modest price, were the real measures of its success.
The BOZAK B-301 is a three-way system based on
a (long -throw, high -compliance bass driver with a
solid low -bass response. The high -compliance
midrange unit with its well -damped
aluminum cone was developed especially
for this loudspeaker system: its clear
definition, or transient response, is
remarkable and we know of no other
that can equal it. The latest version
of the BOZAK high -frequency driver,
originally introduced over twenty
years ago, is highly regarded for
its wide dispersion and silky -smooth
response. All three drivers are of
sturdily
standard BOZAK quality
magnet
with
generous
constructed,
BOZAKunique
structures and
made cones assembled on solid
cast frames.
-
You will have to compare this speaker
system to really appreciate it. And its
especially for a
price is very modest
real BOZAK!
-
the facts:
Bass Speaker: 12" high -compliance,
long-throw/Midrange: 41/2 ", with 25/s"
damped aluminum cone on high -
compliance suspension/Treble: 2", with
foam -damped diaphragm and wide
dispersion/Crossovers: 1200 and 3600 Hz
Frequency Response: 40-20,000 Hz
Impedance: 8 Ohms/Power Handling: 40 Watts
Program average/Acoustical-Environmental Switch:
3-position/Enclosure: oiled walnut,
141/2"x 231/8"x 111/" deep
Grille: snap-out/Weight: 40 pounds.
Bozak, Darien, Connecticut, 06820
Overseas Export by Elpa Marketing Industries Inc.,
New Hyde Park, New York, 11040, USA
Check No. 5 on Reader Service Card
www.americanradiohistory.com
Tape Guide
An innfinite
choice
of speeds.
The variable control Lenco manual
turntables offer an infinite selection of
speed-a continuous sweep from.30
to 86 rpm. At the standard 16-2/3,
33-1/3, 45 or 78.26 rpm, there are
click stops that can be precisely set
or adjusted at any time.
With this, you can slow down a
complex rush of notes, the better to
appreciate the inner voices when you
listen next at normal speeds. You can
tune a recorded orchestra to match the
instrument you play, and join in. Your
tuning is not restricted to a paltry
fraction of a note, either. You can
exercise your urge to conduct, choosing
whatever tempo suits you. And you can
use it to extend your knowledge of the
dance or language, or to accompany
your slide or movie shows.
And at every one of these speeds,
Swiss precision takes over. For
example, the Lenco L -75's sleekly
polished transcription tonearm shares
many design concepts (such as gravitycontrolled anti -skating, hydraulic
cueing, and precision, knife-edge
bearings) with arms costing more alone
than the entire L-75 arm and turntable
unit. And the dynamically balanced
8.8 lb. turntable reduces rumble, wow
and flutter to inaudibility.
longer. Or would I get a distortion?
Prices subject to change without notice.
Check No. 4 on Reader Service Card
-
Ronald Brown, Vietnam.
A. You are correct that the faster the
tape speed, the better the recording.
However, in today's state of the art, the
high quality tape machine can achieve
results at 71/2 ips that are virtually indistinguishable from those at 15 ips. In
fact, a few can even do so at 33/4 ips.
For home recording there no longer
seems to be much purpose in operating
at 15 ips with a really good tape
machine. On the other hand, for professional purposes, where a tape may be
copied several times, with some deterioration in quality with each copy, the
slight advantage of 15 ips operation
appears worthwhile.
I was
planning to build the tape recorder into
the wall and to put the tape preamps in
a desk.
When recording, how high should the
VU pointer go?-Jerry Ubels, New Westminster, B.C., Canada.
A. I suspect that if you change the
existing wiring arrangement between
your tape transport and the tape amplifiers you may run into problems of hum
pickup and treble loss.
If your tape machine's VU meter is
properly calibrated, you should ordinarily set recording level so that the
pointer does not exceed 0 VU. But this
is only a general statement. Depending
on the nature of the sound source, you
may find that sometimes there is no
audible increase in distortion if you
allow the pointer to swing as high as
3 VU; and at other times you may find
it necessary to keep the meter down
to -3 VU or even lower in order to keep
distortion from being objectionable.
Thus if you were recording a live guitar,
with its strong transients, you might
have to keep the pointer down to about
-10 VU. Experience and judgment must
be brought to bear.
Sound On, With, and Over
Q. I am confused by the terms "soundon -sound," "sound-with -sound," and
"sound-over -sound" Could you please
explain these terms.-J. R. SanFilipo,
APO San Francisco.
A. Sound -on-sound means that you
can synchronize two or more sounds on
the same track. To illustrate, record
track 1; play track and at the same
time record the track
sound along
with a new sound on track 3; play track
3 and record the track 3 sound along
with a new sound on track 1; etc. Sound with -sound permits you to synchronize
two sounds on two tracks (not on the
same track). Sound-over -sound permits
you to record on the same track as a
previous recording, but without erasing
the previous recording; this is analogous
to a double exposure in the case of a
camera.
1
Lenco turntables
from Benjamin
33/ ips. I understand that the faster the
tape speed, the better is the tape recording. Your advice would be appreciated
Separating Transport and Amp
Q. I was wondering if I could take the
transport of my tape recorder out of its
case and make the wires to the amplifiers
1
The L-75 complete with handsome
walnut base at $99.50 offers professional quality and versatility but at
far less than studio -equipment prices.
The B55 (lighter platter and an arm of
almost equal specification) is only
$85.00 with base. Both are available
now at your Benjamin/Lenco dealer.
Benjamin Electronic Sound Corporation,
Farmingdale, N.Y. 11735, a division
of Instrument Systems Corporation.
Herman Burstein
Speed Vs. Quality
Q. I am trying to decide
Improving Treble Response
Q. I like my TEAC A6010, except for
its poor treble response at 33/ ips. At
12 KHz, response is about 10 db down at
this speed. What can be done to improve
the treble performance at 33/ ips?Lawrence E. Root, Sacramento, Calif.
A. Improving the treble response of
your tape machine at 33/4 ips may involve
one or more of the following measures:
(1) installing a playback head with a
narrower gap; (2) reducing bias current
at 33/4 ips; (3) introducing additional
treble boost in recording; (4) adding
more treble boost in playback. Which of
these measures is required and how
much depends upon the characteristics
and circuitry of your machine. Also,
some improvement may be obtained
through choice of tape.
Splitting Half -Inch Tape
Q. I am interested in splitting half-inch
tape. Is width extremely critical? What
are the width tolerances?-Paul A. Smith,
Jr., APO San Francisco.
A. So-called 1/4 -inch tape actually has
a standard width of 0.246 inch with a
plus and minus tolerance of 0.002 inch.
Exceeding this tolerance may well raise
problems of tape skewing or sticking in
the tape guides.
between two
tape recorders, one of which operates at
15 and 7' ips, and the other at 71/2 and
6
AUDIO
www.americanradiohistory.com
have a problem or question on tape
recording. write to Mr. Herman Burstein at
AUDIO
134 North
Thirteenth
Street.
Philadelphia, Pa. 19107. All letters are
answered Please enclose a stamped, selfaddressed envelope
If you
OUR 25th YEAR
JANUARY 1972
Our Engineers Didn't Mind Spending
Three Long Years Creating Ampex's
BiDirectional Head For The Micro 155,
The World's Most Advanced Cassette Unit.
AMPEXGA2=M155
What Got Their Goat Was Our Measly Price Tag.
Put ;ou -;elf in the shoes of
the Q.npex engineers. First.
you sgend three exhausting
years an a half -million dollars dev loping the bi-directional heed. The only cassette
heat on the world that can
erase, o ay and record in both
directions. And because there
is but ßFl Deep -Gap head for
all nodes, tape alignment is
always perfect. It's the biggest
recc-ding breakthrough since
the -assette itself. That's why
Ampex had it patented. And
included
a
three-year
war-anty.
Thei you take this amazing
hear and build it into the
Micro 155 stereo cassette
You rclude four -source mixing -or reel-to-reel versatility.
You add a tape selector switch
that adjusts bias and equalizat on -vhen switching from
standard to chromium dioxide
tape, which puts the 155's frequency response at a fantastic
40-15,000 Hz.
And solenoid assisted con-
trols for faster, smoother
operation.
Dual capstans for perfect
head -to-tape interface in both
directions.
Plus an Ampex/Starr slot -load
system. Pause control. Repeat
function. Automatic reverse.
Automatic shutoff and eject.
Hysteresis synchronous
motor. Noise reduction
switch. Automatic level control. Two lighted
V.U. meters.
Finally, the time comes for the
ultimate test. You s ide a cassette into the machine and
turn it on. You listen. And a
tear comes to your eye. Be-
cause you're experiencing
fidelity you never imagined
could be achieved by a cassette machine. You've done it!
Then you hand it over to the
marketing boys at Ampex.
-hey look over your creation,
the result of 36 months of
blood, sweat and tears, and
say "Hey, not bad. We should
be able to move this baby at a
ridiculously low
price.'
Then you design
the most futuristic -looking tape
machine in the industry. Because
you feel that the
best one should
You walk out in a
daze. Then you
cry a lot. Don't
look uniquely
most advanced
different.
www.americanradiohistory.com
machine and priced it so any-
body can afford
it. How can
anyone appreciate the
sophistication and versatility
of the Micro 155 at such a
measly price? Oh, well. Just
hope that the man who buys
this machine takes the time
to learn about everything that
went into it. Then he'll have a
greater appreciation of everything he gets out of it.
AMPEX
those guys know
what they've
done' They've
taken the world's
cassette
l'HG
SIIII\II IIII;A PEOPLE
yNpCO
What's New in Audio
Metrotec SD4A-1 decoder -amp
AMP
NIT
Communications Co.
RT 60
timer
SCA-80Q
$169.95 Kit
$249.95 assembled
Check No.
7
on Reader Service Card
This unit measures reverberation time
in real time and does not require a
chart recorder for analysis. The timer
has a self-contained ni -cad battery and
uses one-third octave band pass filters,
centered on 250, 500, 1000, 2000, and
4000 Hz. Digital readout is provided.
Price: $395.00.
the same cost
as 2 channels
Check No. 8 on Reader Service Card
SSI MM 3000
A true 80 watts rms amplifier, complete control center
and 4 -Dimensional decoding
system in one compact unit.
With 4 speakers you can now
hear all your music
tape,
disc and FM
as it was
meant to be heard in full 4Dimensional realism. Or, use
2 speakers for conventional
stereo now, and add a pair
later.
The SCA-80Q Kit is in the
- -
Dynaco
This unit combines an E -V Stereo-4
four-channel decoder with a 10 watts/
chan. amp (rms, 8 ohms). Separate front
and rear decode channels are offered,
providing ambience in the rear channels
with no loss of separation for existing
two -channel sources. Harmonic and IM
distortion are less than 0.8 percent,
while power bandwidth is 15 to 50K Hz.
S/N is 80 dB. Price: $139.95.
Pansonic SH -8780 demodulator
tradition of un-
turntable
This turntable and automatic tone arm
feature straight line radial tracking for
zero tracking error. A passive analog
circuit does not use wires to transmit the
signal from the pickup head which is not
connected to the support rod by pins or
screws and can be easily removed for
maintenance. The turntable has automatic reject at the end of each disc,
as well as user controlled start, pause
and reject. Platter weight is 3 lbs, and
its diameter is 121/4 in. The drive motor
is a hysterisis synchronous, outer rotor
type. Price: $249.95.
Check No. 9 on Reader Service Card
Designed to work with the CD -4 (RCA,
JVC) system, this four -channel disc
demodulator is said to have low distortion, high signal-to-noise ratio, and
accurate separation. A selector switch
is included for the specific cartridge
type-semiconductor, moving magnet,
or ceramic. A four-channel indicator
"eye" lights up when such a record is
played. Conventional two -channel discs
may be played through the unit. Price:
Not yet established.
matched value. It is the perfect complement to Dynaco
Aperiodic speaker systems.
See your dealer for this low
cost way to truly superb musical reproduction.
alynraco vc_
3060 Jefferson Street
Philadelphia, Pa. 19121
Check No. 6 on Reader Service Card
AUDIO
8
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
THE CRITICS HAVE PUT THE
COMPETITION
PLACE
IN THEIRconsumer
publications
have
testing
continually top -rated Sherwood receivers over all others. Our S-8900
shown here leading the pack is no exception.
Of course, we worked hard to get those ratings.
The S-8900 has a powerful 225 watt (± 1dB) amplifier (48 watts
RMS per channel at 8 OHMS). FM distortion is the lowest in the
industry -0.15%. There's an impressive 3 year parts warranty,
plus 1 year labor, too.
The S-8900 features solid-state ceramic FM IF filtering. Exclusive
FET FM interchannel hush control. A zero-center tuning meter.
There's an extra front panel tape record/ dubbing jack. And six
pushbuttons for every effect
you could possibly want.
At $399.95, our S-8900
gives more top-rated
uality than any
comparable or lower
priced model.
That's what
we've always said.
Only now you
'don't have to take
r word for it.
For more
information and
complete specifi,.
Lions, write us
': today. Sherwood
..Electronic Labor és, Inc., Dept. A,
00 North California
Avenue, Chicago,
Illinois 60618.
Specifically, the leading
SHERWOOD
SOUNDS EXPENSIVE.
Check No. 10 on Reader Service Card
www.americanradiohistory.com
Dear Editor
Dolbyized FM Broadcasts
Dear Sir:
Much has been said in your magazine
about the application of Dolby processing to FM broadcasting. The whole
whole basis of Dolby (type B) is to boost
treble during low-level passages; the
response is then flattened during
normal or maximum -level passages.
A complementary device is supposed to
be used to de -process the audio. However, should we assume that there will
always be level changes sufficient to
derive benefit from Dolby processing?
In my opinion, the typical rock music
FM station will not receive a benefit
from Dolby sufficient to justify the
expense. How many of you have
actually watched modulation meters at
a rock station (as I have)? Level changes
sufficient to activate the Dolby equipment may represent 1% or less of airtime and on some days they may never
happen at all!
Many radio stations in this country
(rock and otherwise) do not allow drops
in audio level; they employ typically
20dB or more of automatic volumecompression and an uncertain degree of
manual compression (they "ride the
gain"). Such stations pride themselves
on being "tight"-which is broadcasting
slang for allowing no lapses in audio
whatsoever.
Many (if not most) recordings are
already highly compressed these dayseven many classical recordings. While
it is true that Dolby processing may
extend the dynamic range of commercial recording, I believe that the final
product will always be subjected to
compression. This is especially true of
rock music where the general rule seems
to be to cram in as much subjective
loudness as possible.
As a matter of fact, several rock stations on FM in this country are
automated and the equipment will
automatically reject the very kind of
audio which would benefit from Dolby
processing! It's called "silence sense"
and it's intended to never allow silence
on the air because of expired tape or a
defective machine. However, this gadget
is a troublemaker sometimes because it
may reject the occasional soft or slow
passage in the music. So, as a matter of
self-defense, the tapes for the automation are subjected to lots of automatic
and manual compression (and even
some clipping) during preparation-then
the station compresses it even more on
playback. After all this ... it goes to the
Dolby. Do you think there will be many
level changes on which the Dolby will
operate? I think not!
Too many of us are guilty of thinking of FM as it used to be. Classical
music with wide dynamic range was
once FM's specialty. I would like to see
a poll taken to determine how true this
is today.
I do not believe in the rationalization
which says that FM benefits from Dolby
even if the complementary receiver
circuit is not used. (You could install
any kind of "black box" and some
people would swear it sounds good.) If
the de -processing is not used the
response will not be flat at all times.
Isn't a flat response one of the primary
objectives of FM in the first place?
FCC regulations specify more flatness
on FM than on AM.
If the FCC rules that Dolby can be
used at all times, then they will require
that all manufacturers build -in the
Dolby circuits in all new receivers. This
will render obsolete thousands (perhaps
millions) of FM receivers already in use.
Nine out of ten receivers in use cannot
easily be converted. Those with seperate
tuners and preamplifiers could do it
easily, but that kind of set is in a very
small minority today.
Is all the expense and bother really
worthwhile? This change would be made
for the sake of a minority of listeners
with border -line reception. Let me point
out that the FCC (for good reason)
limits the range of a station by limiting
the power which may be used. It is not
logical to use a gadget such as Dolby
to extend the range-that's an attempt
to bypass the reasons for limiting power.
Clyde E. Wade, Jr.
Little Rock, Ark.
The basic advantage of the Dolby
system is the increased signal-to-noise
ratio, and in the recent tests by Chicago's
WFMT, a classical music station, listeners in fringe reception areas reported
a dramatic decrease in background noise.
Listeners without Dolby decoders were
told to adjust their treble controls and the
majority of these people said the overall
sound quality was improved.
In theory, the service area of a
Dolbyized station is increased by a factor
of three, and even if we cut this in half,
it still leaves quite a sizable minority.
As for distorted program material from
many FM stations, Clyde is absolutely
10
right. But if those stations will not derive
any benefit from a Dolby system,
presumably they will not spend the
money!-Ed.
Pro Playboy
Dear Sir:
Only one word on "Hi-Fi at the Playboy Mansion"-fantastic.
T. T. Niyaoka
Fremont, Calif.
And Con
Dear Sir:
The Playboy article read like a story
in a women's (or men's) magazine.
Bjorn H. Lambrightsen
Los Angeles, Calif.
Allison Revisited
Dear Sir:
In his November, 1970, article, "The
Loudspeaker/Living Room System."
Mr. Allison makes several unwarranted
assumptions.
It is true that concert -hall music recordings are closely miked, thereby
creating an effect unlike that which the
audience normally hears. It is also true,
however, that the recording engineers
who mix the eight or 16 channels down
to two, use monitor speakers to determine the final balance and tone
coloration. The result is, in their
opinion, a realistic sound. Incidentally,
given the combination of different
models of monitor speakers and differences in human judgment, the same
set of master tracks may come out quite
differently when released by two different recording companies.
Another unfair assumption is that all
music to which one will listen is concert
music. Will all recordings benefit by
superimposition of concert-hall acoustic
curves? Jazz and chamber music, for
instance, are generally heard in intimate surroundings, not concert halls.
Related to these points, however, is
the emphasis on natural ambience to
allow for derived four-channel sound.
If recordings already possessing con -
AUDIO
www.americanradiohistory.com
(Continued on page 82)
OUR 25th YEAR
JANUARY 1972
The end of the fidelity gap
between cassette and open reel.
Our RS-275US brings the low noise, wide-response performance
of open reel to'a cassette deck. Freque-cy response: 301,000 Hz.
Signal-to-noise ratio: better than
45 e3. Those are numbers you've
Probably never seer_ before in
cassette.
The biggest ream- for our
noise and wider response
r
also:he smallest. Par_asonic
_ow
is
rat
rated a Hot Pressed Ferrite
_,ear with one of the world's
narrowest, most precise gaps.
You get a 25% broader frequency
oesponse with ten times the life of
torn entional heads.
A separate fast-fotward and
rewind motor means we don't
lave tospin wheels with our
drive motor. The motor that
drives the tape drives it directly.
No bests to give you. the slip.
No gears to startfluttering and
wowing. The speed is constant.
So is the lack of noise. Our
patented drive motor is DC and
brushless. No AC hum. No brushes
to spark up static.
We're quiet in other ways,
toc. There's a special noise
suppression circuit with =ts own
switch And a tape equalization
switch for the newest low -noise
super tapes.
Nobody else has all these
low-mise, wide-response features
in one great cassette deck.
And that's',ust for starers.
Yot Ilfind solenoid push-
button operation far electrical.
not mechanical switching.
A "memory rewind' button thct
pre-sets :he tape to stop rig_it
where you want it to. Two big
VU meters. Separate output
volume level controls before :he
signal goes into your amplifier.
Optional remote control.
And a walnut base as part of
the deal.
When you're ready to get
serious about a stereo cassette
deck, see your franchised
Panasonic Hi-Fi dealer for the.
RS-275US. The one fl=at gives you
reel sound.
Panasonicc
j.ist slightly ahead cf Dur time.
C0
Park Ave., N. Y. 100 7 For your nearest
rarch
sied
C -reck No
Fanasonic Hi-Fi dealer, call 800 E3"-1971.
11 on
Reader Service Card
www.americanradiohistory.com
In N. J..
8009E2-2803. We pay for the cal
Behind The Scenes
Bert Whyte
1
IBEGAN to write about four -channel
stereo in 1969. Now, writing this
first column for 1972, it comes as a
mild shock to realize that this major
advance in sound reproduction is still
in its gestation period. However, there
are many signs and portents which lead
me to feel that sometime during this
year four-channel stereo will finally
come to term and become a viable
entity in comsumer audio.
I think it is important to understand
that when four-channel stereo becomes
a commercial reality, it will appear in
a number of configurations. The term
"four -channel stereo" is very loosely
used these days. Consider these permutations for example: whether the format
is discrete open reel tape, discrete Q-8
cartridge or matrix disc, if the music is
of the pop "surround sound" type with
equal amplitude fore and aft, it is,
strictly speaking, four-channel monophonic sound. Discrete open reel tape
and discrete Q-8 cartridge can give us
true four-channel stereo with the rear
channels reproducing ambient information. The matrix disc cannot of course
give us true discrete four -channel
stereo. However, the rear channels can
carry somewhat compromised ambient
information, which from a' psycho acoustic viewpoint may present a fairly
effective simulation of stereo. I
personally feel that the tape formats
and the disc will co-exisf. The suggestion put forth by some people, that tape
utilize the matrix system, is patently
ridiculous. Why take the ideal format
for four-channel stereo and subvert it
with a matrix, just to save on tape?
Sure, discrete open reel tape is the
purists' medium. Those who can afford
and appreciate the advantages of this
format, should not be penalized with a
compromised product.
Speaking of matrix systems, I'm sure
you all have read the advertisements
about various decoders. You have also
read about the Dyna system. You have
heard terms like "derived four channel stereo" and "ambient extraction" bandied about. The gist of these
ads is that you can feed your ordinary
garden-variety two -channel stereo discs
into a decoder (with amplifiers and
speakers for the rear channels of course)
or in the case of the Dyna system, one or
two extra speakers, and obtain "four channel stereo effects." Well, with all
due respect to all involved, this is not
even a simulation of four -channel
stereo. In the first place, the recovery
of "sum and difference" information is
strictly a matter of happenstance. In
other words, you encounter this in-
formation on a random basis; it is not
a constant factor in all recordings. In
the second place, if the record does have
some left minus right information, it
is reproduced in the rear speakers without the time delay characteristic of a
true four-channel stereo recording. In
other words, in a typical four-channel
stereo recording, depending on hall
acoustics, the "rear" microphones pick
up the multiple reflections from the
walls, ceiling, and floor some numer of
milliseconds after the onset of the initial
wavefronts of the instruments of the
orchestra. Ideally, the delay should be
no more than 33 to 35 mS, which is the
limit of sound fusion in the brain. More
than that, and you encounter echo and
"slapback." Now don't get me wrong!
The word "enhancement" covers a lot
of ground, and I know quite a few
people who are very pleased with this
"derived four-channel stereo." It is
just not the "McCoy," not the "real
thing." For those who enjoy this kind
of sound, especially the Dyna advocates,
here is a tip for.you: In the early years
of the stereo disc, from 1958 through
1963, London, Angel, and Deutsche
Grammophon were using the European
"MS" (middle/side) stereo recording
technique. This utilized a cardioid and
a figure -eight microphone placed together, with the cardioid facing forward
and the figure -eight at right angles to
the cardioid with the "loops" of the
"eight" to the left and right. The mikes
were hung at an appropriate height and
distance from the orchestra on the
centerline of the hall. (A bit later special
stereo mikes with the two patterns in a
single housing were evolved for this
task.) This "MS" mike technique
produced a lot of left minus right information, and with your Dyna hookup
you can extract this information on
virtually every record made during that
era. With our American "spaced array"
mike technique (which is now used by
almost every recording company here
and in Europe), finding the difference
information is mostly a matter of luck.
So dig out all of those older stereo recordings made by the companies I
mentioned if you want practically
guaranteed results!
One can readily understand that
people who have a lot of money invested in a large stereo record collection would opt for any technique
that offered a simulation of four channel stereo. Most of the techniques
available rely heavily on psychoacoustic
phenomena, such as the well-known
Haas precedence effect. The thing one
must accept is the evidence of one's
12
ears, in spite of the fact that intellectually you know you are being fooled.
If the techniques are sophisticated
enough, such as the Eargle process
tapes I described some months ago,
the four -channel stereo simulation is
virtually perfect. As you may remember,
Mr. Eargle used a combination of time
delay, plus reverberation and selective
equalization in his process. His was
strictly a studio technique, but one of
the most important aspects of the
process, the time delay, can be applicable to four-channel stereo simulations
in the home. It goes without saying that
whether real or simulated; four-channel
stereo requires four channels of
amplification and four speakers.
The most readily available and the
least expensive form of time delay
available to the audiophile are the
well-known spring reverberation units.
There are a number of units on the
market, differing mainly in the length
of the spring and in damping methods.
Some units use multiple springs. In any
case, while this type of delay can be
surprisingly effective, these units are
all easily over -driven, and even with
moderate input they produce a characteristic "boinnggg" sound which is
distinctly. artificial and unpleasant.
There is one spring unit, a joint development of Harman-Kardon and the
ParaOrban company, which not only
affords delays as long as 7 ms (quite a
bit for these devices) but has a very low
residual "boinnggg" noise. At the
moment, plans to market the unit are
sort of up in the air.
One of the most simple, but most
effective means of time delay was
devised by Madsen of the Danish Bang
and Olufsen company. On a standard
tape deck he mounted a special playback head with a double gap, with
separate playback pre -amps for each
gap. (Bad nomenclature here because
what we are really dealing with is a
double head.) The distance between the
first and second gaps determines the
delay, in this case, 10 ms. In practice,
the signal from the first gap goes to the
front amplifiers and speakers, the signal
from the second gap, is the same information delayed 10 ms and sent to the
rear amplifiers and speakers. This
technique restricts one to the use of
tape ... but is that bad? Unfortunately,
as far as I know there are no plans to
market the device at the present time.
There are two electro -acoustical
devices for the generation of time
delays. One is a Japanese product
(whose brand name I've sworn not to
reveal at this time) which is sold every -
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
Pioneers new
SE -L40 stereo headphones
flabbergasted the experts.
High fide ity dealers are probably the
most blase guys in the world. They've
seen eve-ything. -They've hears
everything You really have to have
something ex_raordirary t.: im ress
them. So when vie irtrccuced the new
Pioneer SE -140 stereo headph:ies
at a recent home enfertairnent
electronics show for dealers. we sere
its enti jeiasti:
overwhelmed
reception. We expected aop ause.
We received an o,ratibn.
These super critics m3-.eled at
the new open -a r :es gn w?' ich
enhances he intimacy of Fersoialized
listening_ -hey enthused over the
incompa-able bass -eproduction
achievec by a oorr:binat oh cf ^echnological advances anc newiy developed
speakers nestled in'o each earpiece.
They lauded the ext-ene I ght weight,
nearly one third less than present
headphones. They' conclusion: the
SE -L40 is 3 co- glete departure from
quality pioneer headphones
frcm $24.95.
U.S. Pioneer Electronics Corp
178 Commerce 9oac. Carlstadt,
New Jersey 070.2
when eou want something better
conventionality.
If you re Et s<ept ca and oelieve
that Pionee- high ticelity cealers went
overboarc wish their acclaim for
SE -L40, There's orly one way yoc're
going to oeconvircÿ i_
Visit a Pioneer Beale- and listen.
SE -L40 stereo headphones,
$39.95. wi h carrying case. Other
I
.
_.
AVE
1.FaS
At.G
L£ CALIF
..,
33248
,..__
E
Al6k9A. S. H PAFKSR
...,
_.
,
__.
_
._
CO.,I
_.
www.americanradiohistory.com
For more about the B&W 70CA speaker, write Linear Devices Incl
148 French St., New 3runswick, N.J. 08901. Or call 201 846.7777
The finest speaker
costs $660.
You need two.
in :he world
Check Nc. 14 on Reader Service Card
McIntosh
CATALOG
and FM DIRECTORY
Get all the newest and latest information on the new McIntosh Solid State equipment in the McIntosh catalog. In addition you will
receive an FM station directory that covers all of North America.
where in the world ... except the United
States! Basically a quadraphonic preamplifier, the unit has within it, a honeycomb type of plastic extrusion which
is actually a continous air passage of
some 58 feet in length. At the beginning
of the tube a tiny mylar-dome transducer is sealed in place. A third of the
way down the tube, a tiny microphone
is inserted in the tube and sealed. Another third of the way down the tube is
a similar mike and at the end of the last
third of the tube, still another mike.
These mikes are connected to standard
mike pre -amplifiers, with control pots.
The positions of the mikes in the tube
give delays of 15, 30 and 45 ms, the amplitude of each being separately adjustable. Used with restraint this unit is
capable of some interesting simulations.
The drawbacks are a certain "honkiness"
a nasal sound to the delay, a considerable attenuation of high frequencies, and rapid increase in
distortion if driven too hard. I think
with some modifications to correct
these deficiencies, this unit has considerable potential.
A much more sophisticated electroacoustical delay tube has been devised
by the very clever Professor Duane
Cooper of the University of Illinois.
A full description of the device was
presented by the inventor in the April
and May 1971 issues of AUDIO.
Essentially a looped copper tube is
used, with appropriate driver and pickup elements and an equalizer circuit.
The delay obtained with this unit is
on the order of 14 to 16 ms, and is said
to be wide band, with low distortion
and a good signal-to-noise ratio. Mr.
Bill Putnum of United Recording in
Los Angeles has concluded an arrangement with Prof. Cooper to manufacture
the delay tube as a commercially
available product, and I have been
promised an early production prototype
with which to experiment. The anticipated price of the unit is around
$600.00.
IVI
X 112
FM STEREO/AM TUNER PREAMPLIFIER
-ALL
SEND
TODAY!
SOLID STATE
McIntosh Laboratory Inc.
2 Chambers St., Dept AE11
Binghamton, N.Y. 13903
NAME
ADDRESS_
CITY
STATE
ZIP
For the ultimate in delay devices and
for those with Texas oil baron pocketbooks, we have the Delta T, the
invention of two MIT professors. This
is a totally solid-state device which
accepts analog signals, converts them
to digital and stores them in a memory
core, and then reconverts to analog with
delays available up to 320 ms in 5 ms
increments. The Delta T is distributed
by the well-known professional audio
firm, Gotham Audio Corp., of New
York. Mr. Eli Passen of Gotham was
kind enough to furnish me with a Delta
T unit, and I have spent many hours
experimenting with this fascinating
instrument. Most high quality pre-amps
have sufficient output to drive the Delta
(Continued on page 74)
14
Check No. 15 on Reader Service Card
www.americanradiohistory.com
AUDIO
JANUARY 1972
HARMONIC D STORTION CURVE
POWER OUTPUT
CHANNEL 60 WATTS RMS
1
10
0.9
0.8
Both channels driven simultaneous y
into Bohm load
0.7
0.6
0.5
0.4
a3
a2
at
0.05
0
100
20
1K
OK
20K
FREQUENCY IN HZ
It's the only receiver with the VaritronikTM
FM tuner-with 4 FET's and balanced
Varicap tuning for lower distortion and for
higher sensitivity. By using 4 FET's instead
of ordinary bi -polar transistors, cross
modulation problems are virtually eliminated. And by using 4 double Varicaps
instead of a conventional mechanical tuning
capacitor. a better balanced circuit performance is achieved with perfect linear
tracking. The 725A's FM tuner also uses a
combination of Butterworth and crystal
filters for better selectivity and stereo separation. And, it features an advanced muting
circuit with full muting at 2.5 µV for quiet
tuning without loss of stations. Specifically,
here's how the new Altec 725A receiver
performs. Harmonic distortion is a low
0 3%, IHF sensitivity is 1.8 µV and capture
Altec's new 725A AM/FM stereo receiver
gives you 60/60 watts of RMS continuous
And it includes many extra features to
make it the most versatile receiver on the
power. The 60 watts of power per channel
you hear with the new Altec 725A receiver
is not IHF music power at 4 ohms for just
an instant. It's not music power (plus or
minus dB) either. And it's not peak power,
or EIA power or any other rating. Instead,
it's 60 watts of RMS continuous power per
channel with both channels driven simultaneously at 8 ohms from 30 to 20,000 Hzrated in the same manner used exclusively
by the professional audio field and by quality
testing labs. With this much power you
hear clean, accurate sounds at all frequencies from even the lowest efficiency speakers. And you always have enough power in
reserve to hear that extra -low bass.
market. The new Altec 725A receiver
includes a long list of standard features like
2 separatetuning meters. spring -loaded
speaker terminals, and 100 percent modular construction. In addition, it includes
these "extras" for more versatility and
convenience.
Pushbutton controls for stereo reverse,
mono L & R, low and high filter.
Indicator lights on all functions -AM, FM,
phono 1 & phono 2, tape, auxiliary, tape
monitor and FM stereo.
Tape recorder input & output on front panel.
A heavy-duty fluted aluminum heat sink.
Accessory jacks for theAltec AcoustaVoicette Stereo Equalizer.
ratio is 1.3 dB.
Built a little better.
1
ALTE[
LANSING
ITS COMPANY OF LTV I ING ALTEC. INC
Altec's new 725A AM/FM stereo receiver
sells for $699.00. It's built a little better than
anything else you can buy. Hear it at your
Altec dealers. Or, write fora new, complete
25 -page catalog Altec Lansing, 1515 S.
Manchester Ave., Anaheim, CA 92803.
Check No. 16 on Reader Service Card
lriig0
too
22
1
102
1E3
10o
ton
1pe
1á5
RECEIVER
tae
1Ço
STEREO
Altec's new 725A receiver.
It's built a little better.
www.americanradiohistory.com
Editor's Review
NEW LAW, passed by President Nixon on
AOctober 15th, confirms that a sound recording may be subject to statutory copyright protection if "the sounds constituting the
sound recording as published were fixed on or
after February 15, 1972, and that the sound recording is first published on or after February
15, 1972 with copyright notice in the form specified by this law." Application forms for registration of claims to copyright in sound recordings
can be obtained from the Copyright Office, Library of Congress, Washington, D.C. 20540.
Meanwhile, Viewlex, Inc., a company active in
the audio-visual industry, has announced an ingenious new system designed to prevent record
and tape piracy. The basis of the system, which
was developed in conjunction with the United
States Banknote Corp., is a visible stamp affixed
to the record cover. This would contain magnetic
particles interspersed throughout the ink mass to
form a unique magnetic field. Thus, the authenticity of the record could be checked visually or
by a magnetic verifier, which can be used by the
retailer. Now, all this may sound like an elephant
straining at the proverbial gnat but in this case
the gnat is worth some $100 million-the amount
the industry loses every year to piracy of one
kind or another!
Quadraphonics
In May, 1971, the vice president of Motorola
said, "The report that Motorola was abandoning
the discrete four -channel system in favor of matrix is completely erroneous .
.
We are completely convinced of the superiority of the discrete four -channel systems as contrasted to systems which use synthesizers or matrix techniques.
Our committment and confidence in the discrete
concept is total." That confidence appears to be
a little shaken because in November Motorola
said they would offer a combination matrix -discrete system later this year. On the other hand,
RCA seems firmly committed to discrete and has
joined the JVC, Panasonic line-up. Preliminary
press reports mentioned a "hard substance" for
the MPX records which was supposed to come
from Yugoslavia. This was denied by RCA-the
reporter was probably carried away by the fact
that the Yugoslav president was over here at the
time, possibly after a different kind of hard
stuff
.
Headphones
Doubters who went almost into hysterics over
the "impractical" four -channel headphones described in our June, 1970 issue are now reminded
.
...
that there are at least three similar phones on the
market-including one from E -V with built-in
matrix.
Show Dates
The IHF is planning at least five high fidelity
shows this year, and the first one will be held at
the Royal Inn, Anaheim, California, from January 28th to the 30th. It will be followed by the
Atlanta show on February 18th to the 21st at the
Merchandise Mart. Teresa Rogers, who was responsible for the successful Washington show is
the organizer.
The third event is scheduled for March and it
will take place either in Philadelphia or Cleveland. Dealers in this city of Brotherly Love are
far from being enthusiastic, so Cleveland is the
most likely venue.
30,000 Words per Minute
One of the most interesting devices on show at
the recent AES exhibition was a variable speed
control which enables a tape to be speeded up to
almost 500 words per minute without changing
pitch and producing that "Donald Duck"effect.
It works by removing parts of the waveform in
proportion to the speed
-something like the old
German Hellschreiber. It
is intended for educational purposes, particularly for blind people
who can assimilate material faster than most of
us. Inventors are the
Cambridge Research and
Development
Group,
Bridge St., Westport,
Conn. 06880.
Humor in Advertising"Put your ladybug wherever your like. Wall mounting is perhaps most common, but why not
experiment a bit? Put it on the table, the floor,
a shelf in the corner. Keep trying
As you
might have guessed by now the ladybug is a
loudspeaker, and it comes from Sinus of Sweden.
The leaflet goes on to say, "You never have to
plague it with excessive power." Heaven forbid
But perhaps the largest system would suit
more of our readers ..."designed for those whose
listening tastes have been honed to perfect pitch."
Right on!
G.W.T.
..."
....
16
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
Playing records with some cartridges is like
listening to Isaac Stern play half a violin.
The trouble with some stereo
cartridges is that they don't offer
even reproduction across the
entire musical spectrum.
In the important
upper audio frequencies,
some cartridges suffer as much
as a 50% loss in music power.
So, there's a lack of definition
in the reproduction of violins, as
well as clarinets, oboes, pianos,
the organ and other instruments
which depend on the overtones
and harmonics in the upper
frequency range for a complete
tonal picture.
The Pickering XV -15 cartridge
delivers 100% music power 100%
of the time. Which is why we call
Pickering XV -15 stereo
it "The 100% Music Power
cartridges are priced from $29.95
Cartridge." At 100% Music
to $65.00, and there's one to fit
Power, all the instruments are
anything you play records with.
distinct and clear, because the
For more information write:
XV -15's have no music -robbing
output drop anywhere in the entire Pickering & Co., Inc.,
101 Sunnyside Blvd., Plainview,
audio spectrum. It makes an
Long Island, New York 11803.
enormous difference!
Cartridge power does this to the instruments:
A 50% music power cartridge
can mask some musical instruments.
The Pickering XV-15 gives you
100% Music Power 100% of the time.
I
I
I
I
20
40
II
80 100
200
II,,,
I
400 800 1000 2,0004,000 10,000 20,000
FREQUENCY Hz
0
40
80 100
1
i1111111.11111
i
glI
1
200
I
I
I
1
1
400 800 1,000 2,0004,000 10,000 20,000
FREQUENCY Hz
Pickering. The 100% music power cartridge.
"for those who can hear the difference"
All Pickering cartridges are designed for
use
with all
2
and 4 -channel matrix derived compatible systems.
Check No. 17 on Reader Service Card
www.americanradiohistory.com
How to evaluate FM stereo tuner performance
Daniel R. von Recklinghausen*
buyers' guides are published which present a summary of the performance characteristics
of tuners and receivers. Every month magazines publish reviews of this equipment in which they present the findings of their tests. Seemingly every week advertisements,
in newspapers or magazines, in catalogs or through the mail,
vie for the prospective buyer's attention. Once the prospect
is ready to buy a tuner or receiver, he may receive advice
from his friendly salesman in addition to the advice he has
gotten from his friends, neighbors, and relatives. How can he
assimilate all this and then make a rational decision?
There should be several factors influencing a decision.
Broadly, they may be classified as convenience factors (or
"features"), cost, and performance capabilities.
The most important convenience factor which may influence
a decision to select a tuner or receiver is the desire to have all
operating controls on one piece of equipment. In this case a
receiver (or tuner -amplifier combination) is the obvious choice.
If little space is available to install the electronics, the same
choice should be made.
Tuners, without the added audio controls of an amplifier,
generally permit greater flexibility in connecting a high fidelity
music system and permit equipment of various manufacturers
to be used. This simplifies the up -grading or modification of
such a system at a later time.
Tuners often duplicate some controls of an amplifier,
such as noise filters or level controls. They also require their
own chassis and enclosure with panel and knobs, as well as
power supply components to operate the receiving circuits.
Since many of these parts are also required in an amplifier,
this duplication makes the combination of a separate tuner
and a separate amplifier more costly than a receiver. In the
early days of high fidelity equipment, when only tube circuits existed, there was the feeling that the tuner portion might
be of a lower quality in receivers than in tuners. Principally,
the heat generated by the vacuum tubes was thought to cause
the tuner circuits to drift. Even back in the "tube" days, the
designers were able to lick this problem, which now, in the
"solid state" days, is no longer of any consequence. Tuner
performance in receivers can be and is fully as good as found
in separate tuners.
The last, hardest and the most important step remains:
The evaluation of the performance capabilities of a tuner.
Only one question really need be answered: How many
stations' programs will the tuner reproduce and how well?
It is often impossible to compare all tuners under consideration
side -by-side in one's home, comparing the quality of each
station's signal, because for a complete listening test, signal
quality and interference susceptibility must be compared for
each tuning position-a truly imposing task.
The majority of high fidelity equipment users live either
in the city or its suburbs. The majority of the 4350 AM sta FVERY YEAR
tions in the United States, the majority of the 2750 FM stations, and the majority of the 900 TV stations are located in
metropolitan areas. The local AM and FM stations will most
likely carry different programs since the Federal Communications Commission (FCC) ruled that AM and FM stations under
the same ownership may not duplicate more the 50% of their
programs if they are assigned to the same city of more than
100,000 population. Unless all the AM programs are of no
interest to the listener, or he has enough AM radios, it is wise
to consider the purchase of an AM/FM receiver or tuner
rather than the FM -only variety.
Even though AM broadcasting stations have to provide at
least 5000 Hz frequency response, and many of them provide
as much as 15,000 Hz response, interference from other stations and many electrical appliances will make wide frequency
range listening difficult in most locations. For this reason the
FM reception capabilities of a receiver are considered more
important.
Again, keeping the metropolitan FM listener in mind, the
FM tuner will have on the average three or four strong local
signals (and perhaps as many as 24) picked up by its antenna.
These signals will tend to intermodulate with each other in the
RF amplifier and converter stages of the tuner, causing spurious signals and crossmodulation products to be generated.
These stray signals will usually appear on frequencies other
than those occupied by the local signals. They may masquerade as "other" stations but really are nothing but a
repetition of the local signals. If these signals were to appear
only on unoccupied channels they would cause no harm except that of repetition. More than likely, these stray signals
will interfere with weaker, more distant signals and may
even obliterate them. Consequently, the number of listenable
FM stations is reduced from what it could be.
In choosing a tuner it is wise to select one which resists
overload due to strong signals, i.e., a tuner which has good
crossmodulation rejection. Crossmodulation rejection (or
spurious response rejection) is measured in dB in accordance
with the standard of tuner measurement published by the
Institute of High Fidelity. The number may be thought of
as representing the "dynamic range" of r.f. signals the tuner
is capable of accepting without problems.
At least 70 dB crossmodulation rejection should be available
for metropolitan FM reception if other than local stations only
are considered as program sources. Higher numbers are, of
course better, with each additional 6 dB permitting signals
of twice the field strength (corresponding to approximately
one-half the distance to a transmitting antenna) to be available
to the tuner without trouble.
Since the IHF crossmodulation measurement is performed
with only one interfering signal, and since interference may be
caused by several signals of varying strengths, a high cross'Technical Director, H. H. Scott, Inc.
18
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
modulation figure is not an absolute guarantee against all "captures" the interference. This selectivity curve (made
forms of tuner overload due to strong signals but it is still according to the procedure outlined in the IHF tuner standard)
the best available performance indicator. A set of inter- is a dynamic selectivity curve and does not show the response
ference measurements on one tuner under all possible signal of a selective filter measured in the conventional manner.
conditions would take a very long time. A full report might be
At a frequency difference of 0 kHz a special selectivity point
the size of one volume of an encyclopedia and would be is measured-it is the capture ratio. This ratio indicates the
harder to interpret.
ratio of signals required for the tuner to reproduce the stronger
An abundance of strong and weak FM signals are the typical
of the pair while rejecting the weaker.
conditions in a metropolitan area. In the writer's home (in a
In the example shown, the selectivity curves are shown for a
suburb of Boston) 41 different listenable FM signals were re- desired signal equal to that giving IHF usable sensitivity and
cently counted using a high -quality tuner operating from a
for a desired signal 20 dB stronger. For weak signals, the refolded dipole antenna located indoors on the ground floor sidual noise provides a second interfering signal, resulting
of a frame building.
in the slightly wiggly curve shape between ± 100 kHz. At
To receive this many FM stations (when available) requires
stronger signals, the noise influence is eliminated and the true
a tuner of high selectivity. FM stations are assigned by the
two -signal selectivity curve emerges. The measured "capture
FCC to 100 channels 200 kHz apart, ranging from 88.1 to ratio" is also improved.
107.9 MHz. In any one locality, stations are assigned to chanFrom these curves, it can also be seen that weak adjacent
nels 800 kHz or more apart. Stations in nearby areas are as- channel signals may be received if the receiver is tuned
signed to frequencies in between. These may be assigned to off to the side so as to discriminate against the interfering
the adjacent channel (200 kHz away), the alternate channel signal. Of course, detuning causes distortion, but detuning
(400 kHz away) or perhaps the third channel (600 kHz away).
is usually made so as to minimize the total of audible disSelectivity for an FM tuner is measured for the interference tortion and interference products.
experienced when tuned to the desired channel, with a stronger
Selectivity, when reported as a single number, denotes the
interfering signal fully modulating the alternate channel. It point on the selectivity curve which is 400 kHz from the
is measured in dB, with a higher number indicating better
desired (center) frequency. For asymmetrical selectivity
performance.
curves, the center frequency is assumed to be located halfSelectivity and bandwidth of a tuner are linked together. way between the two (low and high frequency) intersections
While selectivity may be thought of a measure of rejection of of identical selectivity spaced by a total of 800 kHz.
signals away (in frequency) from the desired signal, bandSelectivity curves of practical tuners are always slightly
width may be thought of as denoting the width of the signal asymmetrical because coupling of the selective elements is
spectrum of the desired station accepted by the tuner.
generally by some reactive rather than a resonant elements.
The width of the signal spectrum depends not only on the Selectivity curves of tuners which use mechanical elements,
maximum deviation of the instaneous station frequency from such as quartz crystal or ceramic resonators, as selective
its average (and assigned) carrier frequency, but also on the elements usually show substantially reduced selectivity at the
modulation frequency. The FCC defines 75 kHz deviation as higher frequency portion of the selectivity curve and also
100% modulation for an FM broadcasting station. Since audio
show a substantial reduction of the slope at selectivities in
signals have both plus and minus values the station frequency excess of, say, 45 dB. This is usually caused by a combinavaries both above and below its average value, resulting in tion of electrical and mechanical coupling and by other than
instantaneous frequencies spread over a range of 150 kHz. desired resonant modes of the ceramic or crystal elements.
The actual spectrum occupancy of the transmitted signal is
larger because the actual transmitted frequencies are not instantaneous but involve an infinite number of "sidebands"
(of the carrier) when the carrier is deviated at a modulation
frequency rate. These sidebands decrease in strength at frequencies further away than the "deviation" from the carrier, yet
e e ...
e* ._._,
the tuner must process all of them for truly distortion-free
reception. This could not permit any selectivity because of the
requirements for "infinite" bandwidth. The elimination or attenuation of sidebands away from the carrier causes distortion.
Calculations for a special ideal (and therefore mathematically
treatable) filter indicate bandwidths of 265 kHz and 225 kHz
if harmonic distortion of 1% and 3% respectively may be tolerVIAL
ated at certain modulation frequencies. Practical, well--_
'.;
designed filters produce less distortion than these figures for
..
__
the same bandwidths. Since such a bandwidth includes some of
the channel space assigned to adjacent -channel stations, and
since selectivity is measured with a 100% modulated signal,
it is evident that very little selectivity is obtained for adjat
cent channel signals. The figure may even be negative, indicating the need for a stronger desired signal compared to
the interfering signal. For this reason, selectivity is measured
9,e
for alternate channel signals.
The full story of selectivity is not found in a single selectivity number, but in a selectivity curve as seen in Fig. 1.
Here, the desired signal is indicated by a cross, denoting its
ll'li'
strength and relative frequency. The interfering signal is
-I
represented by a curve. This curve shows the frequency of
the interfering signal and its strength adjusted so that the
desired signal predominates in the audio output and therefore Fig. 1-Selectivity curves and level of desired signal.
MODEL
DATE
100000.0
:
:
800
1
NE
10000.0
1000.0
DESIRED
A
6B ABOVE IMF
USABLE SENSITIVITY
TEST INPUT
DESIRED
_QIIALT
IGNAL
IMF
SABLE SENSITIVITY _.
10.
;PTURE RATIO
1
dB
CAPTURE RAT
01
1200
00
-600
-4%
CENTER
AUDIO
OUR 25th YEAR
JANUARY 1972
-400
0
200
FREQUENCY OF INTERFERING
4%
6
SIGNAL
19
www.americanradiohistory.com
shows the stereo signal-to-noise ratio. The rated values are
usually found at the 100011V level.
It should be noted that the "N" curves merge with the
"S +D +N" curve for a 0 input signal.
In the range of the IHF sensitivity input, the "mono N"
curve for the ideal tuner shows its steepest decent, with the
noise output decreasing in the steepest portion as much as
dB increase in signal level. Non -ideal tuners will
6 dB for a
show a lesser figure.
Once the mono signal-to-noise ratio has reached about 48 dB,
the noise level will decrease proportionally to the signal increase (a dB signal increase causes a 1 dB noise decrease)
w
until the ultimate signal-to-noise ratio has been reached. The
48 dB point shows the "knee" for mono performance, while the
25 dB point of the stereo signal-to-noise ratio is the "knee" of
the stereo performance.
The third set of curves show the total relative undesired
output of the tuner, i.e., the total of noise and distortion with
Fig. 2-FM performance.
respect to the total output. They are labelled "mono
the
Overload of the input circuits of a tuner will also cause this N+D/S+D+N" and "stereo N+D/S+D+N". In
at
dB,
and
0
approach
curves
these
any
signal,
of
absence
curve.
widening of the selectivity
The next set of curves which should be examined when moderate to high inputs they show the total distortion of the
tuner. At all levels, these curves have a higher value than the
selecting a tuner are those often published under the general
corresponding "mono N/S+D+N" and "stereo N/S+D+N"
title of FM characteristics. An example of these is shown in
curves (which are not shown). In the steep transition region,
curve,
output"
Fig. 2. The first curve of interest is the "audio
more
showing total tuner output voltage due to 400 Hz, 75 kHz thecorresponding mono or stereo curves should be no
to
suspected
may
be
tuner
the
Otherwise,
apart.
a
few
dB
than
the
(300
deviation monophonic, modulation with respect to
ohm) antenna input signal. This output contains the audio sig- be of narrow bandwidth-which should also be reflected by
nal, its distortion, and whatever noise there may be; it is relatively high stereo distortion.
The signal level at which the "mono N+D/S+D+N" curve
labelled "S+D+N."
the -30 dB line is the point of IHF usable sensitivitycrosses
for
input
constant
The ideal tuner shows this output to be
and the rated value for this is the highest number of microvolts
signals in excess of approximately 5 µV. At the signal level
found at the carrier frequencies of 90, 98, and 106 MHz.
corresponding to IHF usable sensitivity, the audio output
As may be imagined, listening to programs at the usable
will have decreased by approximately 1 dB and in the absence
input is not a hi-fi listening experience, but measuresensitivity
than
lower
of any input signal will be approximately 15 dB
ment at this level can be repeatedly performed and is valuable
its "normal" output value. These figures assume that the
limiter is fully limiting with the random noise generated in as a basis for comparison. For example, enjoyable mono listening requires signal-to-noise ratios in excess of 50 dB. Some
the first amplifying stage of the tuner. Only by this action can
tuners may reach this at the IHF input level, and others may
frequency
to
is
sensitive
one be assured that the tuner
modulation only and does not respond to amplitude modu- require as much as 6 dB higher signal level. Here, the shape of
the curves will help decide this fact.
lation.
Enjoyable stereo listening also requires at least 50 dB signalAt this point it should be noted that the term "full limiting"
ratio. As can be seen, substantially higher signal levels
to-noise
audio
relative
arbitrary
denoting
some
has been misused-often
output or signal-to-noise ratio rather than its proper meaning- are required-from 10 dB to over 20 dB above the IHF test
input.
the removal of amplitude modulation.
These figures illustrate that substantially more useful inPractical FM tuners approach the ideal S + D +N curve
can be obtained from a few sets of curves than from
formation
than
more
lower
(by
markedly
which
show
very closely. Tuners
a list of numbers.
6 dB) audio output at 0 input signal probably have inadequate
How can a metropolitan listener evaluate the various sensigain for weak signal processing and may not be fully adequate
for critical listening. Tuners which show a variation in audio tivity curves? If he lives in the middle of the city in a tall
output of more than 2 dB for signals stronger than their usable steel-and -concrete building without access to an outdoor
sensitivity signal, may be inadequate for many high-fidelity antenna he faces most difficult signal reception conditions.
installations because the normal audio output may vary audibly Not only will he not be likely to be able to receive the direct
unreflected signal, but he will be subject to a conglomerate of
during moderate signal fading experienced when aircraft cause
signal reflections, varying considerably in signal strength from
as
"airplane
known
phenomenon
to
vary
(a
signal
the received
flutter") by adding a varying multipath reflection to the direct fairly weak to very strong. His signals will be often pure
"multipath" and laced with pulse noise interference from autostation signal.
The second set of curves, labelled "mono N" and "stereo N" motive traffic and other sources. Such a listener should choose
his tuner to have good spurious signal (crossmodulation) rejecshow the residual noise output of the tuner when subjected
tion and to have good performance for signals of weak to high
to an unmodulated ("mono N") carrier signal or one moduintensity. Extreme sensitivity is not required because signals
lated with a 19 kHz stereophonic pilot signal ("stereo N").
below 5µV may be riddled with man-made noise. The selecAt moderate to high input signals, these curves will be horitivity requirements in the city are usually moderate (30 dB or
and
the
tuner
of
noise
residual
the
total
showing
zontal,
more), because distant signals will be severly attenuated and
generator circuits. The "stereo N" curve may also contain
often buried in noise.
passing
38
kHz
signals
and
19
kHz
of
the
amounts
residual
The suburban listener usually has better signals available;
through the audio filters of the tuner and some stereo modugenerally all of them, local and distant, are stronger than those
lator and demodulator noise.
The distance in dB of the "mono N" curve to the S + D +N "downtown." His tuner still must have excellent spurious
response rejection. Since listenable distant signals are available,
curve shows the monophonic signal-to-noise ratio of the tuner,
a prime requirement should be good selectivity (40 dB or
+
+N
curve
and the distance of the "stereo N" curve to the S D
00
ON ANTENNA
TERMINALS
CNCS TO SI EREO NITR INCREASING SIGNAL
-
TONES TO MONOwuN DECREASING SIGNAL
1
1
- 70
AUDIO
20
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
We enjoy telling you how each aspect of the 12
year basic research program on sound reproduction
contributed to the unconventional features found in
the Bose 901 and 501 DIRECT/REFLECTING® loudspeakers.* We also take pride in quoting from the unprecedented series of rave reviews because to us they
are like awards won for the best design.t
However, it is important to realize that the research and the reviews are of only academic interest
unless the speakers really are audibly superior. It is
equally important to realize that YOU are in every
sense the ultimate judge, for you are the one who lives
with the sound you choose.
So-forget the rave reviews and the research and
sit in judgement of two fascinating experiments. Take
your most exacting records to any franchised BOSE
dealer and:
1. Place the BOSE 901's directly on top of any
other speakers, regardless of their size or price, and
make an A -B listening test with your records.
2. Place the BOSE 501's beside (with at least 2 feet
clearance) any other speaker using woofers, tweeters
and crossovers and perform the A -B listening test.
(Don't ask the price of the 501 before the test)
Then, just enjoy your records. When you finish you
will know why we get much more satisfaction from our
work than could ever be derived from profits alone.
P.S. If you already own expensive speakers, many
dealers will lend you a pair of BOSE 901's for an A -B in
your living room, where th,e acoustics are generally far
superior to those of the speaker -lined showroom.
* Copies of the Audio Engineering Society paper,
'ON THE DESIGN, MEASUREMENT AND EVALUATION OF LOUDSPEAKERS', by Dr. A. G. Bose, are
available from the Bose Corp. for fifty cents.
t For copies of the reviews, circle our number on
your reader service card.
You can hear the difference
noz.ABO
Unless they're audibly superior
it's all academic.
The BOSE 901 and BOSE 501 are covered by
patent rights, issued and pending.
Check No. 21 on Reader Service Card
www.americanradiohistory.com
LL-
REFLECTOR
t
(BUILDING)
m-
ANTENNA
REFLECTED SIGNAL
(
MILE
ROUND TRIP DELAY
SIGNAL FROM
TRANSMITTER
100.1 MHz
.s
75
kHz
DIRECT SIGNAL
-411
.4
100.025
MHz
,
100.100
100.175
100.025
MHz
MHz
MHz
SEC
110.4.1N
RELATIVE SIGNAL STRENGTH
Fig. 3a-Simple multipath caused by one reflected signal
and one direct signal.
if
il
1
S
[11
100.02S MHz
100.050MHz
100.0SMHz
100.I00MHz
100.125 MHz
21
100 ISO
\
-
---
--
1,10
100
MHz
100.175
MHz
RELATIVE PHASE
Fig. 3c-Amplitude and phase response of total transmission
path containing one reflection.
as much as possible of the little
signal available. An antenna rotator is a "must."
Two very important FM tuner characteristics are usually
not reported in curve form and one of them is even difficult
to express as a number. The first of these is the AM suppression.
The signals broadcast by the FM station are modulated by
varying the transmitter's frequency while keeping its power
output constant. All the tuner circuits in the transmitter and
its antenna system are usually adjusted to minimize any output variation. The tuner circuits in the receiver usually are of
narrower bandwidth than those of the transmitter since they
have to select the desired signal and reject signals on other
frequencies.
For this reason, the received signal at the input to the
limiter stages will be attenuated by 0.5 to 3 dB (in typical
tuners) as the signal varies from its center frequency to the
rectional antenna to capture
DIRECT SIGNAL
REELECTED
SIGNAL
RESULTANT
SIGNAL
100.175 MHz
Fig. 3b-Vectorial addit:jn of direct and reflected signals
vs. frequency.
more). Sensitivity of a tuner need not be extreme, but must
not be sacrificed at the expense of spurious responses. Since
the man-made noise is lower than in the city, good signal-tonoise ratio with moderate to strong signals should be sought.
The minority of rural listeners should place sensitivity of
a tuner high on the list, followed by good signal-to-noise ratio. Most important is a good installation of a high -gain di-
Wow and flutter 0.1%, lowest of any stereo
cassette deck at any price.
Sony's exclusive closed loop dual capstan tape drive system solves a major cassette
problem-pronounced wow and flutter. This
system (shown here) helps make the Sony 160
Soiy keeps the
and 165 stereo cassette decks perform better
than any other. Why? Because it drives the
tape at a constant speed, exerting the same
amount of tape -to -head pressure from one
end of the tape to the other. (Not only a steady
pressure but the correct amount of pressure
to reduce modulation distortion drastically.)
In addition, both Sony decks are
equipped with a built-in Peak Limiter. A
unique first, it automatically monitors the
recording level preventing tape saturation
and distortion without audibly altering the
dynamic range while you're recording.
There is also a tape select switch that
enables you to change the record equalization for either standard or the new chromium
dioxide cassette tapes.
www.americanradiohistory.com
maximum deviation. This in effect is incidental amplitude
modulation of the FM signal. occurring at twice the audio
modulation frequency. If the tuner were fully sensitive to this
amplitude modulation, its detected signal would experience
3% to 17% distortion. Fortunately, the limiter circuits (along
with the detector circuit) remove most of the amplitude modulation, and low distortion reception is possible. The effectiveness with which these circuits remove this amplitude modulation is known (and rated) as amplitude modulation rejection and is measured in dB. Any high fidelity tuner worthy
of the name should have at least 40 dB AM rejection when
measured with 30% AM. Claims of AM rejection in excess of
60 dB are within the realm of the possible, but are difficult
to verify since normal laboratory test equipment is generally
not capable of generating AM signals sufficiently free of incidental frequency modulation.
Good AM rejection in a tuner is required not only for removal of incidental amplitude modulation generated within
the selective circuits but also for removing as much audible
distortion as possible when receiving signals under multipath
signal conditions.
As the name indicates, multipath means that the signal
reaches the receiver's antenna by a multitude of paths, each
having a different loss, and because of their length, a different delay. The effect may be demonstrated as shown in
Fig. 3a. Here, just two signal paths are considered, a direct
path and a path involving a reflecting obstacle (a hill or a
group of tall buildings) located about one mile away. This
.
would cause the reflected signal to have a delay of approximately 10 microseconds. The direct and reflected signals add
vectorially in amplitude and phase as shown in Fig. 3b. The
resultant now has neither the amplitude nor the phase of the
original signal. As the frequency of the signal changes, the
relative phase of reflection to direct signal changes 360° for
every 100 kHz of signal change. Thus, there may be as many
as two instantaneous signal maxima or minima within the
normal ±75 kHz modulation range in this example. The resultant amplitude modulation may now include strong components of fourth harmonic distortion of a strength determined by the ratio of direct -to -reflected signal.
The limiter circuits will probably remove most of the incidental amplitude modulation, but they will not affect the
phase of the resultant. This phase now varies with deviation
of the carrier. Since the carrier is deviated by the modulation signals, the resultant also phase modulates the signal.
This in turn is an incidental frequency modulation of the
signal-but one increasing with modulation frequency and
containing practically pure distortion. Consequently, under
multipath reception conditions, distortion increases with modulation frequency and is most serious at the highest modulation frequencies-those which contain the stereo sub -channel. This is the main reason for stereo reception in cities
being often unacceptable when monophonic signals sound
much better.
No high fidelity tuner can remove multipath signals. (Extremely complex circuits may be able of minimize multipath
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problems, but they require laborious adjustment, and so far
only the military services have been able to experiment with
them). The best cure for multipath problems is the use of
a directional antenna along with careful orientation and adjustment. Even indoor antennas of the "rabbit ear" kind can
be used with good effect and may be most practical when
readjustment is required for each signal.
To minimize multipath problems requires one additional
tool, the multipath indicator. As shown above, the increased
high -frequency distortion or stereo distortion may be used
with the ear acting as an indicator. Unfortunately, the ear is
not a reliable tool, particularly when the broadcast station
does not "cooperate" by playing music containing a lot of
high frequencies or by playing stereo material.
The best results can be obtained when a multipath indicator is connected to the tuner. An oscilloscope may be connected to many tuners to display multipath. Essentially, these
connections involve vertical trace deflection with an output
containing a signal proportional to signal strength, and horizontal deflection with the FM detector output. Detailed information for connections will have to be obtained from the
manufacturers of these tuners, or their representatives or
dealers.
Other tuners may have these connections already provided
and some of them contain built-in multipath indicators such
as oscilloscopes or meters. By just being able to adjust the
antenna for the best signal, these tuners will be able to give
results superior to other installations when difficult multipath
"'";72r".."2,°:%,7.
10
Fig.
4-Tuner
frequency response.
,;. _.,
Fig.
5-FM
stereo separation.
000
reception conditions exist. These difficult conditions can be
predicted with good accuracy in most any city having tall
buildings, and in any hilly or mountainous area. Flat country
or over -water signal paths are rarely subject to serious multi path problems.
The next important tuner characteristic not reported as a
curve (or even a number) is the tuner's pulse noise rejection.
As shown above in the section on selectivity, the capture ratio indicates the tuner's ability to have the stronger of two
signals predominate in its output while suppressing the
weaker one.
When a tuner is subjected to a noise pulse, the pulse should
"capture" the signal from the station for the length of time
in which the pulse is stronger than the signal. The strength
of the pulse in the FM band caused by a passenger automobile ignition system may be 1000 microvolts per meter at
a distance of 500 feet. This is 20 times stronger than the
old "grade B" service contour of 50 microvolts per meter of
an FM broadcast station.
It is important that the pulse cause no worse problems than
capture of the signal. As soon as the pulse becomes weaker
than the signal, the signal should predominate and no transient due to previous pulse overload should remain. A single
pulse should sound as a "tick" pretty much regardless of its
strength and not as a "pop". In particular, a pulse or a series
of pulses, should not be audible with the receiver tuned offstation. If pulse noise were audible under this condition,
listening quality for other than local stations may be impaired.
All the previous tests and curves have documented the important aspects of tuner performance from antenna to the
final FM detection. The group of curves in Figs. 4 and 5 describe the performance of the circuits which handle the detector output.
Figure 4 shows the audio frequency response of the tuner
circuits. It is shown as a normal frequency response, including the response above 15,000 Hz, the maximum audio frequency broadcast by a stereo FM station. The region above
15 kHz shows how well the 19 kHz pilot signal and the 38
kHz re-insert carrier signal are removed from the tuner out-
put. These frequencies may cause intermodulation with the
bias oscillator in tape recorders and the recording of whistle
frequencies.
The frequency response is also shown with respect to the
standard 75 microsecond de-emphasis curve. It shows how
accurately the signals are reproduced. This error should be
less than +2 dB between 50 Hz and 15 kHz, the limit frequencies for FM broadcast stations.
Figure 5 shows the stereo separation of a tuner. As may
be appreciated, more information can be gleaned from a
curve than from a single figure, say, 30 dB separation and
without specification of frequency.
For good listening, the tests performed by the Bell Laboratories and by General Electric show that at least 20 dB
separation be available over the range of 100 to 8000 Hz.
Most tuners are capable of exceeding this figure-but only a
curve will prove it.
There are many more tests which can be and are performed on tuners. They may deal with more refined aspects of the
characteristics discussed above, or they may deal with squelch
performance, tuning indication, drift, or many other factors.
In all cases, the basic characteristics analyzed here should
be considered most when choosing a tuner or receiver. Only
after these have been evaluated with respect to the expected
signal conditions for city, suburb, or country should other
convenience features not discussed here be analyzed.
Last, but not least, reliability and reputation, leadership in
technology, and soundness of design should be evaluated. The
IE
tuner bought today should give years of good service.
AUDIO
24
www.americanradiohistory.com
OUR
25th
YEAR
JANUARY 1972
Introducing
the Fisher 801.
If you want
four channels,
very high power
and wireless
remote tuning,
you have no
The 801 is Fisher's new top -of-the-line
-channel receiver. It costs $749.95. Everything
hat Fisher knows about receivers has gone into
is design. Which leaves out very little.
Discrete and matrixed 4 -channel, no watts
usc power -}1 db (44 watts rms per channel), electronic
FM tuning with- no moving parts and a separate wireless
remote tuning unit are only the beginning cf its features.
To appreciate the full quality of this new flagship of
the Fisher line, you must read the detailed technical
literature. There's no other way. For your free coçy, write to
Fishy Radio, Dept. A-1,11-44 45th Road, L.I.C., N.Y.111C1.
PHICE GI.IGHI.Y NIGHER IN THE FAR WEST.
FISHER
We
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invented high fidelity.
Men of Hi-Fi
The Perfect FM Tuner
The following is a partial transcript of Harry Maynard's Men of Hi Fi program, which is now presented each week from 10:00 to 10:55 p.m. on New
York City radio station WNYC-FM. Mr. Maynard, Contributing Editor of
AUDIO, writer and hi-fi buff, had as his guests for this program Leonard
Feldman, another Contributing Editor of AUDIO, and Dick Sequerer, designer of the Marantz 10B.
performance. It's a more stable system,
a more predictable system.
MAYNARD: Why, because it uses crystal
MAYNARD: Good evening, ladies and
gentlemen. Tonight we're going to
talk about the ideal FM tuner, and what
such a tuner consists of. Dick, I understand that you're designing a tuner
which will sell for $1500.00 and be the
state of the art. What will be this
fundamental components?
tuner's
When we last talked on this program,
you mentioned some of this new tuner's
virtues. But just how do you visualize
it. I asked you last time whether or not
it would be a digital tuner and you said
let's leave that to the next program.
SEQUERER: Digital tuning, in and of
itself, is just a way to readout the station
that you are tuned to. Behind the digital
tuning is an extremely stable type of
tuning system, so that this is really what
makes digital tuning valuable. It's
not the numbers that you readout; it's
just as easy to read a sliderule dial,
for instance. But you now, without
spending a fortune for the type of
ganged capacitors that were used, let's
say, in the Marantz 10B, can make a
device which is extremely stable and
very long lived, with modern circuits,
no mechanical or moving parts. And,
of course, when you do away with
moving parts, you make a device which
is going to last longer, that's going to
be more predictable, and essentially
going to give better service. So, in terms
of what I'm making now, I frankly will
tell you that I haven't made up my mind
as to whether to have a digital dial,
sliderule dial, or even both.
MAYNARD: How would you vote for
controls?
Yes, that's right.
In that light, I would prefer
other virtue, not for the fact
that I'm getting a nixie tube readout.
SEQUERER: Len is exactly right. The
readout is actually a derivative of
what the thing is really doing.
MAYNARD: Now, Len, suppose you were
talking to Dick and saying, "Here are
some of the things I'd like to see, with
no reference to cost?" What would you
tell him you'd like to see.
FELDMAN: Well, we haven't yet discussed selectivity. I'd like to hear a little
bit from Dick on this subject, because
it's been a bugaboo with me.
MAYNARD: I have had other people on
this program, who have claimed that
too much emphasis has been put on
sensitivity, too much money has been
put into a tuner to give these great
sensitivity readings, and it might be
better to invest some of the money
that has been put into achieving these
great sensitivity readings into some
other aspect of the tuner.
SEQUERER: If you look at sensitivity in
the proper frame of reference, I think
you can really understand its importance
or unimportance. High fidelity or high
quality broadcasting or music-listening
type systems need signal-to-noise
ratios of almost 60 dB. And that should
be the real criterium of the sensitivity.
In other words, where the tuner really has
SEQUERER:
FELDMAN:
it, for its
this, Len? We're talking about the
ideal FM tuner, with cost no question.
FELDMAN: Yes, but it is after all a trade
off. In other words, given the option of
having a digital readout versus superior
performance, I would forego the digits
in favor of the performance, because,
as Dick points out, you can read a
sliderule dial and the stations do identify themselves, even if the dial is off
a hairline. So, I'd rather see the money
put into performance, rather than readout.
SEQUERER: I don't think I made myself
very clear. Actually the digital dial concept, as it is considered by most lay
people in the business, really is better
26
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
The new Dual 1218.
It has already become the most
popular turntable Dual has ever made.
The Dual 1219 has been the most widely
acclaimed turntable we have ever produced.
As measured by the published results of the
independent test labs. And the many high
fidelity professionals who use it in their
personal systems. As well as by the thousands
of music lovers who made the 1219 the best
selling quality turntable of all time.
All in all, the total performance of the
1219 made a tough act totop. But we believed
the new 1218 might well do it.
The 1218 offers most of the features that
have earned such high acclaim for the 1219.
For one example: the twin -ring gimbal suspension of the tonearm
that lets it pivot
just like a gyroscope. For another
example: perfect
15°tracking in
single play. Plus
all these: Pitch-
control. Separately calibrated anti -skating.
One-piece cast platter. Tracking force applied
at pivot. Rotating single-play spindle. Clickstop counterbalance. Cueing damped up
and down. All contribute importantly to
performance, convenience and versatility.
Actually, unless you saw the 1218 and
the 1219 side by side, you might not tell
them apart. (The 1219 at $175 with its fullsize 12" platter and 83/4" tonearm remains
the ultimate.)
But there is one difference that you
may consider important: the 1218 is priced
at $139.50.
And when you consider that
not one of the 1218's
precision features is shared
by any other turntable at
its price, you'll know why it
did not take long for our
prediction to come true.
Dual
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a quieting and a rejection of all noise
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FELDMAN: That is why I've said that the
IHF's standard is meaningless as it's
presently 'written, because you don't
know what happens after that 1.8 µV,
as you go from there to 5 or 10 µV.
SEQUERER: Let me defend part of the
standard, at least so that it can be better
understood. All tuners have what is
called a quieting slope or characteristic
behavior beyond the point that the IHF
has determined is the sensitivity measurement. Unfortunately, there are
no tuners which are around that follow
the ideal or the theoretical quieting
curve, and therein lies the problem.
MAYNARD: This would be a very rapid
drop-off.
SEQUERER: It's a drop-off, right. Now,
this ideal quieting curve, if it were
followed along its theoretical performance by all tuners, then the sensitivity
figure would be valid at any point,
whether it's the IHF or anything else
you wanted. However, as Len properly
points out, these curves do not follow
the ideal because of vagaries and inadequacies in conventional designs.
Therefore, a more meaningful number
for the actual listener would be the point
at which the quieting had reached 55 or
65 dB. And I'm using that broad a
spread on purpose. This includes all
hum, noise, and distortion components.
This would then be the point at which
you have a usable signal, and that's
what we're talking about, a usable
signal for high fidelity.
MAYNARD: Well, now, what are you
going to put into the tuner? I assume
that this is going to be the very latest
in design, the state of the art. What's
going to be in it that no other tuner's
going to have?
SEQUERER: It's going to have a multi pole Butterworth -type filter, similar
to the one that was in the Marantz
IOB, but more elaborate. Very frankly,
we compromised with the Marantz
10B, and it's strictly a question of
money.
MAYNARD: That tuner sold for about
$700.00.
SEQUERER: It was $750.00 and it turns
out that we probably could have sold
it for more, but we did compromise.
MAYNARD: I remember a funny story.
I was standing next to Saul Marantz at
a hi-fi show once and a man came up to
him and said, "Mr. Marantz, I just
bought one of your tuners for $750.00."
And Saul turned around to him and
said, "And that was less then it cost us
to make it."
SEQUERER: Well, that's not altogether
true, but it depends on when he bought
it. If he bought one of the very first,
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would suggest that it was true. It
was a very expensive undertaking for
a small company. We did learn a great
deal in the process. It doesn't seem that
anyone else picked up where we left
off.
MAYNARD: What have we learned since
the Marantz 10B was designed?
I
don't think we've learned
anything, but I'm prejudiced.
MAYNARD: If you're going to go beyond
the Marantz IOB, how do you do it?
SEQUERER: We're going to lower the
distortion by a slug, as we say in the
business. You can't lower the distortion at mid -band over the IOB,
because that was probably close to
theoretical but you can lower it at
15KHz. We're going to improve the
15 KHz separation. We're going to
improve the selectivity. And we're going
to make probably the largest improvement in the AM rejection. We're
looking for something that can reject
80 percent AM.
MAYNARD: Would you agree that this
is a step in the right direction, Len?
FELDMAN: Absolutely!
MAYNARD: What kind of a standard
figure are you hoping to achieve in this
AM rejection area, as compared
with the way it's given now?
sEQUERER: Well, this becomes complicated because now we have to talk about
how to measure it, and how to generate
AM that is similar to the envelope
modulation of multipath.
MAYNARD: Would you explain envelope
modulation to our listeners?
SEQUERER: Everyone is familiar with the
situation of listening to FM and having
a plane fly over and getting flutter.
This flutter is amplitude modulation,
fundamentally, of the FM signal, that
is, of the wanted signal by the unwanted
signal. This is called envelope modulation.
MAYNARD: Len, would you sum this up
for our listeners?
FELDMAN: What Dick is saying is that
the signal which started out as all
FM becomes, in fact, a partly AM signal. That's oversimplifying, but what you
want is pure FM and what you're
given is-unfortunately-a combination
of FM and AM modulation, which
leads to the distortion products we've
been talking about.
sEQUERER: Let me say one other thing,
for the more technically minded in the
audience. All of the information necessary to FM is contained in what we
call the zero axis crossings. Everything else is extraneous. If I add to this
AM, and the set still cannot process
the AM, I have not affected a thing.
Unfortunately, if the set will demodulate
the AM components, they add to the
information that was on the zero
SEQUERER: I
AUDIO
OUR 25th YEAR
axis and form serious distortion. And
to put this more practical terms, these
components are all audible. The tuner
we are envisioning will sound better
to the average listener because of its
significantly better AM rejection.
MAYNARD: Just the way the Marantz
10B sounded better, although on some
laboratory specs, sensitivity figures for
example, the 10B was not extraordinary,
was it?
SEQUERER: Those specs were no better
than anybody else's.
MAYNARD: Why did the Marantz 10B
sound better as it seems to me it often
did?
SEQUERER: For one thing, the selectivity and the shape of the i.f. passband
as it was achieved then, was probably
better than anything else that had been
done before. It led, for one thing, to a
phase linearity over the i.f. system,
which was important for mono and
particularly for stereo.
MAYNARD: And this is going to be terribly important for matrixing systems,
where you have a lot of out -of-phase
information, isn't it?
SEQUERER: It could enter the picture,
yes, providing that matrixing in fact
does become the system of FM four channel broadcasting.
MAYNARD: At least we know-you and I
and a lot of so-called experts-have
agreed that for at least the next three
or four years, if we're going to get
four-channel via FM radio without
any change in FCC regulations, we're
going to have to listen to it via some
matrixing system. Dick, what are you
going to do about four -channel?
I hope you're going to have a design
whereby, no matter what system is
adopted, Dorren or whatever, one would
slip in a simple IC and there won't
be any obsolescence in this $1500 "ideal"
tuner. Is that correct?
sEQUERER: This is correct. I certainly
hope that we're not going to have any
obsolescence in this tuner.
MAYNARD: This doesn't constitute any
problems, do you feel, Len?
FELDMAN: No more than the problem
we faced when stereo was just around
the corner and everybody was providing
detector outputs or building in a facility
for plug-in modules.
SEQUERER: More than that, I think if
the system is truly phase linear in terms
of its FM capability, and it has the low
distortion, and the low AM response, and
the great stability that we're talking
about, it can process anything over the
allocated band. And that's the whole key.
There are many tuners on the market
which will not be able to precess anything.
MAYNARD: Would you agree with that,
Len?
JANUARY 1972
have just one question.
I'm sure you're familiar, Dick, with the
Dorren proposal and that it may involve extension of modulation out to
perhaps 100 KHz. What will happen
with your tuner?
FELDMAN: Yes. I
SEQUERER: Basically in my design work,
I do not measure harmonic distortion
with de -emphasis in the system. I
make a system which will indeed go
to 100 KHz, in terms of its audio modulation.
MAYNARD: Dick, will you sum up the
basic points about your $1500 "ideal"
tuner?
SEQUERER: I think the most important
thing is that this tuner will be ultra stable. It is an instrument, and it will
give many, many years of predictable
performance. That's about all you can
say.
MAYNARD: Entirely solid state?
SEQUERER:
FELDMAN:
Mostly integrated circuits.
What is the projected time-
table, Dick?
am estimating deliveries
of these tuners to selected people,
since this is a very limited production
thing-sort of a hand-crafted Rolls
Royce, if you will-sometime in March.
MAYNARD: I certainly want to be on the
list to receive one of these tuners. What
do you feel the market is?
SEQUERER: Well, I think there is a
market.
SEQUERER: I
,
FELDMAN: I agree. In fact, we were talking about this earlier. I believe that
with a superior product such as this,
that if anything Dick is going to find
that his edition is too limited, because
once the word gets out that such a
product exists, I have the feeling that
he'll have to increase his production
plans.
MAYNARD: What about the market
from FM radio stations? Do you see
that?
FELDMAN: There's a natural market
right now, even before you talk about
the consumer.
MAYNARD: Well, the Marantz 10B is
selling right now-there's no depreciation
on 10B-you have to pay $750 right now
to get one.
SEQUERER: They don't make them anymore.
MAYNARD: Right; that's what I'm
pointing out.
SEQUERER: I think that you'd be hard
pressed to find one. I know I was when
I had to get one recently.
MAYNARD: Dick, I want to thank you
for giving us some of the very interesting
history of the Marantz l0B and for telling us something about your new design. Len, thank you too, for being on
the program and for your always interesting comments on FM tuners and
broadcasting. Good night.
29
www.americanradiohistory.com
Technically,
our new SQ four-channel
system has 4 basic
advantages.
Sony SQ.
A new stereo/quadraphonic system, delivers four
distinct sound channels from a compatible SQ record.
It also offers four distinct advantages over all the
other four-channel "matrix" systems.
Advantage #1:
Greatest stereo separation, front and rear.
Your present stereo system probably can maintain
40 db or so of separation between left and right channels. Maintaining this full left -to-right separation, in
both the front and rear pairs of channels, is one of the
major achievements of the SQ system.
Advantage #2:
Simple logic that lets soloists stay soloists.
When a single instrument is playing, all you want to
hear is that instrument, even in four-channel. A pure
matrix decoder-even the matrix at the heart of SOcan't reproduce a solo instrument without a softer,
phantom soloist in other channels. But by adding a
logic circuit, these phantom signals can be diminished
or eliminated, sharpening your sense of the soloist's
position.
So far, though, only Sony's SOD -1000 and SQA-200
decoders have this logic enhancement. Because SQ's
unique encoding (which shows up on records as a
double-helical modulation of the groove) makes simple logic circuits practical.
Advantage #3:
Total omnidirectional fidelity.
A musician plays no softer when he's behind you
or to one side. With SQ he doesn't sound as if he did.
No matter where in the 360° quadraphonic circle the
musician sits, he will be heard at exactly the same
volume as if he were sitting in front of you. And that's
true whether you're listening to the SQ record in fourchannel or just playing it on a stereo system without
an SO decoder.
Advantage #4:
Equipment by Sony.
Sony offers you a choice of two SQ adapters.
For the more demanding, there's a new SOD -1000
decoder. Its logic circuit enhances front -back separation by up to 6 db, so that front -center soloists (or
rear ones, for that matter), stand out more clearly. The
SOD-1000 lets you listen to four-channel sound from
SO records, or to discrete four -channel tapes on
auxiliary players. It also lets you listen to normal
stereo, or to stereo broadcasts and recordings enhanced with SO ambience. Just plug the SOD -1000
into your tape monitor jacks (the SOD -1000 has its
own), and add your choice of rear -channel amplifier
and speakers.
If you want to get into SQ with a more modest
investment, add Sony's new SQA-200 SQ decoder/
amplifier to your system. It has all the SOD -1000's
features (except the four -channel master volume
control). But because the SQA-200 has a stereo
amplifier built in, it saves you the expense of an extra
amplifier for your rear channels.
Hear SO at your Sony dealer. Or write Sony
Corporation of America, 47-47 Van Dam Street, Long
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New SONY
www.americanradiohistory.com
Musically,
it's starting out
with 52.
Vanguard Records
Columbia Records
Popular
Lynn Anderson, Rose Garden
Blood, Sweat and Tears II
Johnny Cash at San Quentin
Chase
Ray Conniff, Love Story
Al Cooper, Mike Bloomfield
&
Steve Stills, Supersession
Miles Davis, Bitches Brew
Bob Dylan, Nashville Skyline
Percy Faith, Romeo and Juliet
Funny Girl, Original Sound Track
Janis Joplin, Pearl
Kris Kristofferson, Silver -Tongued Devil and I
Johnny Mathis, You've Gota Friend
Jim Nabors, Help Me Make It Through The Night
No, No, Nanette, Original Cast
Poco, Deliverin'
Ray Price, For the Good Times
Raiders, Indian Reservation
Santana, Abraxas
Sly and the Family Stone, Greatest Hits
Ray Stevens, Greatest Hits
Barbara Streisand, Stoney End
Ten Years After, A Space in Time
Andy Williams, Love Story
Tammy Wynette, We Sure Can Love Each Other
Classical
Bach, Switched -On Bach (Carlos)
Bernstein, Mass (Bernstein, Original Kennedy
Center Cast)
R. Strauss, Also Sprach Zarathustra
(Bernstein, N.Y. Philharmonic)
Morton Subotnick, Touch
Verdi, Requiem (Bernstein, Arroyo, Veasey, Domingo,
Raimondi, London Symphony)
Popular
Joan Baez, Blessed are...
Larry Coryell, At the Village Gate
Country Joe and the Fish,
From Haight-Ashbury
to Woodstock (2 LP)
Buffy Sainte-Marie, Moonshot
Classical
"P.D.Q. Bach:'
The Stoned Guest (Schickele)
Berlioz,Requiem (Abravanel, Utah)
Handel's Messiah (Price, Minton, Young, Diaz,
Somary, English Chamber Orch.)
Handel, Messiah highlights
Mahler, Symphony No. 3 (Abravanel, Utah)
Mozart, Divertimenti K287/138
(Blum, English Chamber Orch).
Tchaikovsky Symphony No. 4
(Stokowski, American Symphony)
Tchaikovsky, Serenade Op. 48;
Prokofiev, Classical Symphony;
Arensky, Variations (Somary,
English Chamber Orch.)
The Virtuoso Trumpet of Martin Berinbaum
(Somary, English Chamber Orch).
Ampex Records
Popular
Anita Kerr Singers Grow to Know Me
Anita Kerr Singers with Royal Philharmonic,
A Christmas Story
Bob Hinkle, 011ie Moggus
Melting Pot, Fire Burn and Cauldron Bubble
Mason Profit, Last Night I had the Strangest Dream
Purlie, Original Cast
Cris Williamson
Rome Philharmonic, Classical Movie Themes
Check No. 31 on Reader Service Card
four-channel record system
www.americanradiohistory.com
The Acoustic Feedback
Loudspeaker System
Curtiss R. Schafer
of negative feedback in amplifiers has produced low -distortion, wide -range response that is pleasant to listen to. Until recently loudspeakers have not been able to incorporate inverse feedback.
The classic attempts to apply feedback to a loudspeaker
are described by Olson'. They use either a secondary voice
coil and magnetic structure (with the secondary coil rigidly
coupled to the primary coil), or a microphone mounted in
front of the speaker. In either case, the output of the microphone or secondary voice coil is connected to the input of the
amplifier and out of phase with the input signal.
Another attempt by Holdaway and Denby in 1963 used
negative velocity feedback, with the feedback voltage derived
from a bridge in the voice coil circuit. The paper by Hold away', and another by de Boer', present very interesting discussions of motional feedback'.
These attempts have not been entirely successful because
of the loudspeaker loads'and the modes of vibration of loudspeaker cones'. The typical cone moves as a piston over a
relatively narrow frequency range and usually vibrates in at
least eight different modes over the range from 50 to 10,000
Hz. These modal vibrations involve changing radial and annular sections of the cone, and thus, most of the time, the
voice coil literally does not know what the cone is doing.
For these reasons, I decided on a purely acoustical form
of negative feedback. Judging by the studies cited above, it
seemed that both the speaker unit driven by the amplifier
and the unit used as a microphone would have to possess
very similar characteristics. This immediately suggested another idea: If two similar speakers were to be mounted backto-back in a small enclosure and their voice coils phased so
that both cones moved either in or our at any given instant,
an internal pressure wave would be generated by one cone
that would be 180% out of phase with that generated by the
other cone. This would, in essence, be acoustical negative
feedback and the magnitude of the feedback could be controlled by the resistive and reactive parameters of the air path
between the two cones and also by the use of a T -pad to
increase or diminish the signal supplied to one voice coil.
EDITOR'S NOTE: A "push-pull" system was developed by the
THE CORRECT APPLICATION
SPEAKER UNITS
ENCLOSURE
British G.E. Company in 1959. As might be expected only even
harmonic distortion was significantly reduced'.
To test this concept, two 12 -inch speakers were mounted in
a 15 by 15 by 11 in. case as shown in Fig. 1. The interior was
lined with two-inch pads of polyurethane foam wherever possible.
After a half hour of listening to FM program material, it
was apparent that the bass response went about an octave
lower than that of the acoustic suspension speaker usually
used and the transient response seemed better. These first
impressions were confirmed by several hours of listening to
records.
With this encouragement, I decided to design a wide -range
speaker system that would embody my concept of acoustical
negative feedback using the double speaker arrangement.
Several factors seemed important, first a wide frequency
response (at least 20 to 20,000 Hz), since the widest range
systems always sounded the best if modulation distortion is
low; second, freedom from excessive resonant peaks and valleys; and third, enough acoustic power output for a large
living room.
Other considerations were a reasonable physical size, the
use of a low crossover frequency, only one crossover frequency since the dividing networks produce transient and
phase distortions, and a high proportion of direct rather than
reverberant sound.
I have always considered the highly reverberant acoustics
of a large concert hall to be a necessary nuisance rather
than a quality to be enjoyed. When reverberance predominates, it becomes for me a "mud factor." Recently I listened
to a computer -designed loudspeaker system which used one
unit to produce direct sound but eight units for reverberant
sound. It was like listening to a symphony orchestra in a hall
with bad acoustics; mind and ears are continually straining
to bring some order out of confusion. Under such conditions,
the matter of speaker transient response becomes irrelevant.
Several weeks were spent listening to speaker systems in
dealer showrooms and attempts to get distortion vs. acoustic
power data from the prominent speaker manufacturers. Finally the JBL LE-15A was selected as the woofer because it
sounded best and because the manufacturer supplied a photograph showing the acoustic waveform produced by an input
sine wave of 60 watts at 40 Hz, which indicated harmonic
distortion of only about 5% under these conditions. The
LE-15A has a long voice coil and can maintain excellent
lineraity at cone excursions up to ±'h inch from the center
position (one inch peak to peak):
Judged second best were the lower priced Wharfedale
models W 15/RS and W 12/RS with ceramic magnets. Use of
a ceramic magnet results in a "shallow" woofer design,
which is preferred in this system because it permits the cones
to be closer to each other. These models also have long voice
coils; the W15/RS is linear for excursions of/4-in. peak-to peak. (Wharfedale speaker units are not now available in the
U.S. They can only be purchased in cabinets as completed
systems. -Ed. )
Fig. 1-Schematic diagram of the system.
An evaluation of treble units resulted in the purchase of
a 511-B sectoral horn and a 802-D driver; a PM -7 wide
32
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
15ips
7'hips
0.06%
0.09%
+2dB
40Hz to
30kHz
20Hz to
20kHz
S/N
-60dB
-60dß
Specs
PROFESSIONAL
3 speeds
15, 71/2 &
33Aips; hysteresis syn-
chronous drive motor
w. &
f.
11.
resp.
torque reel motors
STUDIO
EQUIPMENT
"capable of providing
the most faithful reproduction of sound
through the magnetic
recording medium ..
to date" -Audio mag-
computer logic controls for safe, rapid
tape
handling
and
editing;
full
remote
control optional
.
azine,
4/68
optional Trac -Sync
channel
individual
equalizers
monitor
A/B switch;
meter monitoring of
source, tape, output
third
with
head
and
source+tape;
sound - with - sound,
sound -on -sound
and
echo
2
mixing inputs
channel
per
individual channel bias
adjust
"construction
enough
rugged
withstand parachute
drops" -Audio magazine,
$1790 for basic rack mount half-track stereo
deck, about $2300 with
4/68
typical
accessories;
Formica floor console
$295, rugged portable
case - $69
RECORDERS &
REPRODUCERS
SX
modular construction
with easy access to
all 10 moving parts
and
plug-in
circuit
boards; deck rotates
360° in console, locks
to
at any angle
CX822
711
Claimed by its pro audio owners to
be the finest professional tape recorder value on
the market today
price versus performance
Frequency response at 71/2ips ±2dB 20Hz-20kHz,
at 33/4ips ±2dB 20Hz-10kHz
Wow & flutter at
7'/zips 0.09%, at 33/4ips 0.18% S/N at 7'/zips-60dB,
at 33/ips -55dB
Facilities: bias metering and
adjustment, third head monitor with A/B switch,
sound -with -sound, two mie or line inputs, meter
monitoring same as CX822, 60012 output Remote
-
start/stop optional, automatic stop in play mode
$895 for full -track mono deck as shown, $995
for half-track stereo deck
SP72 2
Ideal reproducer for automation
systems
Meets or exceeds all NAB standards
Remote start/stop optional, automatic stop in
play mode $595 for half-track stereo reproducer
Crown tape recorders and reproducers
are available in 42 models with almost
any head configuration, including 4 channels in -line. Patented electro -magnetic
brakes maintain ultra -light tape tension
and never need adjusting. They are made
by American craftsmen to professional
quality standards, with industrial -grade
construction for years of heavy use.
All Crown amplifiers are warranteed
three years for parts and labor. They
are 100% American -made to professional quality standards. All are fully
protected against shorts, mismatch and
open circuits. Construction is industrial -grade for years of continuous
operation.
For more information, write CROWN,
Box 1000, Elkhart, Indiana 46514
STUDIO MONITOR
AMPLIFIERS
D40
Delivers 40 watts RMS per channel at
412
Takes only 13/4" rack space, weighs
81/2 lbs.
IM distortion less than 0.3%
from 1/10w to 30w at 812
S/N 100dB
below 30w output
$229 rack mount
1111.1rr:11
D150
Delivers 75 watts RMS both channels at
IM distortion less than 0.1%
812
from 1/10w to 75w at 812
S/N 100dB
Takes 5%" rack
below 75w output
space, weighs 20 lbs.
$429 rack mount
Check No. 33 on Reader Service Card
www.americanradiohistory.com
DC 300
Delivers 300 watts RMS per channel at
412
IM distortion less than 0.1%
1/10w -150w at 812
S/N 100dB below
150w output at 812
Lab Standard performance and reliability
"As close
to absolute perfection as any amplifier
we have ever seen" - Audio magazine,
10/69 $685 rack mount .
range, double diaphragm unit of English manufacture, and a
Wharfedale Super 10 RS/DD. The PM -7 is designed for horn
loading but I felt that its use as a treble unit would not require much greater cone excursions than its use as the single
driver in a wide range horn system.
When I took the sectoral horn out of its carton, I noticed
that it rang like a bell whenever I rapped it with my knuckles. Thinking it may have been cracked in shipment, I returned it, and then found that the replacement did the same.
The bell -like resonances were quite audible on most program material. Since that time, I have found that most 500or 800 -cycle sectoral horns have this fault. (This ringing 'is
.
normally tamed when the horn is mounted but some engineers
use heavy tape or "Mortite" to kill any resonances.-Ed)
The completed acoustic feedback speaker system is illustrated in Fig. 2. A mirror was placed to show the back of the
cabinet (which is just like the front). The cabinet is 36 inches
high, 27 wide, and 14 deep (front to back). The usual principles of good construction were followed: the top, bottom,
sides, and compartment divider are made of two -inch -thick
black oak; the speaker mounting panels are of one -inch
particle board; all speakers are mounted from the outside of
the panels. The interior of the enclosure is lined with pads of
two-inch polyurethane foam. The whole structure is non resonant, of course.
The two woofers were connected in parallel internally and
phased with a flashlight cell so that both cones move outward
simultaneously. The two treble units were connected in a
similar fashion. The two pairs of leads were brought out to
the dividing network. Several commercially available networks were tried, and I found that an Altec N-500! I gave the
least phase shift in the crossover region of 500 cycles.
Our speaker system was then played through an FM tuner
and one channel of a Dynaco Stereo 120 amplifier. From the
very first moment it sounded good. It has all the qualities I
had hoped for, excellent transient response, a tremendously
solid bass, and good balance between bass and treble. As I
had surmised the effects of negative acoustic feedback are
most evident at the bass end of the range. The impedance
curves to illustrate this are shown in Fig. 3.
After the cabinet had been completed, the foam pads were
put in place and one woofer was installed. The other speaker
panel was left off, so that the enclosure resembled an open backed radio cabinet. The impedance of one woofer was
measured under these conditions, with the results shown in
Fig. 3a. The free air resonant frequency of this woofer is 18
Hz. The impedance was checked with the unit laid on its face
on the standard -volume tee box used in designing ducted port bass -reflex enclosures , with the results shown in Fig.
3b.
Fig. 2-The completed system, with a mirror showing the
back side, which is identical to the front.
`."....727:.'
%
,`,
,
,
10
'.
!
I
o.,
i
,
.a
m.
o
.
I
i
I
I
I
'I
i
i
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,.,,.
..., ., ..
;
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i
i
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100
FM
-0100Y -
11.1
Fig. 3-Impedance curves. A, one woofer with open -backed
enclosure; B, one woofer with standard -volume enclosure,
and C, in Schafer feedback enclosure.
With both panels and both woofers in place again, the impedance curve of Fig. 3c was obtained. (The crossover network was omitted for this measurement.)
The nominal impedance of one woofer is 16 ohms, although the actual impedance at 200 HZ was found to be
about 14 ohms. Thus the two woofers in parallel give an impedance of about 7 ohms at 200 Hz. In the double speaker
system, this impedance shows a relatively small increase at
the fundamental resonant frequency and does not show the
usual rapid drop below this frequency.
The overall frequency response of the system has not been
measured, but apparently ranges from about 10 Hz to a little
over 20,000. Acoustic power output for the two woofers together is estimated at about 0.5 watt. This output is not
adequate for a large concert hall or auditorium, unless more
than one speaker system is used. However, for a small hall
or large living room, its response is as good (15 Hz) as that
of a hyperbolic horn 20 feet long with a mouth 5 by 7 feet'.
It has been A -B tested against several top -rated commercially available systems, and its superiority was apparent
after a few minutes of listening.
Two other acoustic feedback speakers have been built. One
uses a pair of Wharfedale W 15/RS woofers and a pair of
Super 10/RS/DD treble units; the other uses W 12/RS woofers and Super 10/RS/DD tweeters. For each of these combinations, JBL LX5 dividing networks give the minimum
phase shift. These systems were put into smaller cabinets ánd
used less expensive speaker units, but the results, except for
power -handling capability, are similar and almost as good.
34
(Continued on page 73)
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
"AR has done it again...
the best quality and purest wide range sound
available today, at the lowest possible price."
Charles Graham, Down Beat
"... a really terrific performer. The AR-6 has a clean, uncolored, well-balanced response that delivers some of
the most natural musical sound yet heard from anything in its size/price class, and which indeed rivals that heard
from some speakers costing significantly more."
High Fidelity
"... out -performed a number of considerably larger and far more expensive systems that we have tested in the
same way... We don't know of many speakers with as good a balance in overall response, and nothing in its
size or price class has as good a bass end."
Hirsch-Houck Laboratories, Stereo Review
"I am unable to get over the sheer quality represented by the AR-6. To put my wonderment in perspective, perhaps the most telling thing I could add is that I never expected to be saying of any speaker in this price range
that it deserves only the finest possible associated components. The AR -6 does, and that says a great deal about
this product."
Larry Zide, The American Record Guide
The price of the AR -6 is $81 in oiled walnut, $72 in unfinished pine. Five percent higher in West and Deep South.
Acoustic Research, Inc.
24 Thorndike Street
Cambridge, Massachusetts 02141, Dept. AU -1
Please send complete specifications on the AR -6 to
Name
Address
Check No. 35 on Reader Service Card
www.americanradiohistory.com
M 1,c
//èk.<'5.-91717_
7
BERLIN, ER
°+e
4'....p2j2Cop,oNE.
DISC PECOM
,
4
elitteete
\
1.
GARRARD
EIALtam
www.americanradiohistory.com
.4:17.
N
\-...:.:1_.11111111111111e7
On October 7,1971, the Maker of the Microphone Award
was presented to Garrard Engineering, Ltd.,
to recognize "an outstanding contribution to the world of sound"
--the development of a zero tracking error tone arm
for disc record reproduction.
The Award
The "Maker of the Microphone Award" was established in
1963 in memory of Emile Berliner, the great inventor who
developed the microphone, the disc record, the gramophone,
the method of mass-producing records from a master; and
created the trade mark, "His Master's Voice."
The previous winners, recognized for the special significance of their contributions
to audio, have been Roland
Gelatt, Goddard Lieberson,
Dr. Harry F. Olson, The Bell
System, Audio Magazine,
KTBT Radio / Telaudio Centre, NARAS, and the National
Library of Canada. This year,
Garrard is particularly hon-
Emile Berliner 1851-1929
ored, because 1971 marks the
first time the award has been
bestowed on a manufacturer.
error as high as 4 degrees, or
14,400 seconds at its full playing
radius. The tracking error of the
Zero 100 tone arm is calculated to
measure a remarkable 90 seconds
-160 times as small per inch as the
error of conventional tone arms.
The drawing on the right shows
the unique tone arm construction;
the diagram below shows how the
arm articulates, constantly adjusting the angle of the cartridge, and
keeping the stylus tangent at 90°
to the grooves throughout the record. Thus, space-age pivotry and
computerized design have now
made it possible to play the record
at exactly the same angle at which
it was cut. Reproduction is truer,
distortion sharply reduced, record
life lengthened.
The Zero 100 is the only automatic turntable achieving zero
tracking error. Modestly priced at
$189.50 it has an impressive array of innovations above and beyond the tone arm. These include
the patented Synchro-Lab synchronous motor; variable speed control; an illuminated strobe; magnetic anti -skating; viscous-damped
cueing; 15° vertical tracking adjustment; and 2-point record support in automatic play. See your
high fidelity dealer for a personal
demonstration, or write for test
reports and literature to British
Industries Company, Dept. Al2,
Westbury, N. Y. 11590.
-
The Zero 100 Tone Arm
In making the award, Emile Berliner's grandson, Mr. Oliver
Berliner stated ..."Probably the most elusive problem in disc
record reproduction has been that of tracking error. Many
attempts have been made to overcome this. The solution created by this year's award winner is a marvel of simplicity, yet
deceptively so, for many considerations are inherent in what
has resulted in a rugged, low-cost, reliable and near -perfect
solution that is revolutionary and pace -setting in its effect."
A comparison of the tracking error measurements of any
conventionally pivoted tone arm with those of the Zero
100, indicate the breakthrough which Garrard has achieved.
Consider that there are 3,600 seconds of arc in a degree...
and that a conventional tone arm may produce tracking
/
Ar iculating arm
pivot-fixed
Pivot 4
P.U.
arm pivotf ixed
Pivot 1
Articulating
arm
Pickup arm
Pickup arm
pivots in
this
direction as
arm tracks
across
records
Pivot 3
Pivot
2
Pickup arm pivot-fixed
The Zero 100 tone arm.
True tangent
tracking geometry.
fixed
Turnta ble
center
ir-Articulating
arm
P.U. arm
i
2" rad
3" rad.
4" rad.
\
rad
Center line of cartridge
tangential to record groove
,,JÍ
IPivot between
p.u. head and
articulating arm
_
Arc otstylus
Pivot between p.u. arm and
p.u. head-must be directly
above stylus tip.
GARRARD
ZERO 100
A genuine step upward in automatic turntables
Mfg. by Plessey Ltd.
CIRCLE 103 ON
READER -SERVICE
www.americanradiohistory.com
CARD
Dist. by British Industries Company
Neve Receivers H H
All figures quoted are those supplied
by the manufacturers.
* Power output refers to continuous
power (rms) at 8 ohms, both channels driven.
* Power bandwidth refers to the
extreme frequencies where the
power falls by half.
* FM sensitivity is the IHF rating.
Anything less than 3µV is good
with the best measuring less than
2.0.
Capture ratio defines the ability
of a tuner to select the stronger of
*
two stations when both are on the
same frequency. Anything below 4
dB is very good. Note that all receivers are AM/FM unless otherwise stated.
Li
B & O 3000-2 FM only.
Power Output: 30 W per ch.
THD: 0.6%
Power Bandwidth: 10-30,000 Hz
FM Sensitivity: 2.0 µV
Capture Ratio: 3.0 dB
Features: Preset tuning for 6
stations, slide controls, spkr. switch,
2 phono inputs, filters.
Price: $330.00
'
_--------_`
a
{,'
`
BIC/LUX 71/ 3R
Power Output: 50 W per ch.
THD: 0.2%
Power Bandwidth: 15-30,000 Hz
FM Sensitivity: 2.0 µV
Capture Ratio: 2.5 dB
Features: Variable x -over tone
controls, spkr. switch, filters, 3 FM
pre-sets.
Price: $550.00
`
'
Fisher 401
Power Output: 45 W per ch.
THD: 0.5%
Power Bandwidth: 25-20,000 Hz
FM Sensitivity: 2.0 µV
Capture Ratio: 2.8 dB
Features: Electronic tuning, wireless remote control, spkr. switch.
Price: $449.95.
KLH 51
Power Output: 20 W per chan.
Olson RA 290
Power Output: 22 W per chan.
THD: 1.0%
Power Bandwidth: 20-25,000 Hz
FM Sensitivity: 2.8 µV
Capture Ratio: 2.0 dB
Features: Slide controls, spkr.
VM 1532
THD: 0.5%
Power Bandwidth: 9-33,000 Hz
FM Sensitivity: 1.9 µV
Capture Ratio: 2.5 dB
Features: Ceramic i.f. filters, spkr.
Rotel RX-600
Power Output: 42 W per chan.
THD: 0.1%
Power Bandwidth: 12-40,000 Hz
FM Sensitivity: 2.2 µV
Capture Ratio: 2.0 dB
Features: Spkr. switch, tone control
switch, filters.
Price: $300.00
switch.
cancel.
Price: $229.95.
Price: $299.95.
Sherwood S-7100
Power Output: 30 W per chan.
THD: 1.0%
Power Bandwidth: 25-25,000
FM Sensitivity: 1.9 µV
Capture Ratio: 2.0 dB
Features: Spkr. switch.
Price: $199.00 (inc. case)
THD: 0.5%
Power Bandwidth: 15-30,000 Hz
FM Sensitivity: 2.5 µV
Capture Ratio: 2.5 dB
Features: Step-type tone controls.
Hi -filter, spkr. switch.
Price: $239.95.
Power Output: 25 W per chan.
AUDIO
38
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
'PIP
Nikko STA-8010
Power Output: 26 W per chan.
THD: 1.0%
Power Bandwidth: 30-15,000 Hz
FM Sensitivity: 1.8 µV
Capture Ratio: 3.0 dB
Features: Variable x-over tone
controls, spkr. switch, filters, 3 FM
station presets.
Price: $239.95
Radio Shack STA-18
Power Output: 7 W per chan.
THD: 1.0%
Power Bandwidth: 30-20,000 Hz
FM Sensitivity: 3 µV
Capture Ratio: 2.5 dB
Features: Dial pointer lights on
stereo.
Price: $129.95
Kenwood KR 7070A
Power Output: 90 W per chan.
THD: 0.5%
Power Bandwidth: 10-30,000 Hz
FM Sensitivity: 1.5 µV
Capture Ratio: 1.5 dB
Features: Auto tuning, remote
control, spkr. switch, filters, auto
muting.
Price: Not yet fixed.
Marantz 28
Power Output: 20 W per chan.
THD: 0.5%
Power Bandwidth: 20-30,000 Hz
FM Sensitivity: 2.0 µV
Capture Ratio: 2.0 dB
Features: Gyro -touch tuning, filters.
Price: $229.00
AUDIO
OUR 25th YEAR
Toshiba SA -15Y
Power Output: 30 W per chan.
THD: 0.8%
Power Bandwidth: 20-40,000 Hz
FM Sensitivity: 2.0 p.V
Capture Ratio: 2.0 dB
Features: Spkr. switch, filters.
Price: $299.50
-4-;' s'
Standard SR -4500
Power Output: 100 W per chan.
THD: 0.3%
Power Bandwidth: 5-50,000 Hz
FM Sensitivity: 1.5 µV
Capture Ratio: 1.5 dB
Price: Not yet fixed.
Heath AR -1500
Power Output: 60 W per chan.
THD: 0.1%
Power Bandwidth: 8-30,000 Hz
FM Sensitivity: 1.8 µV
Capture Ratio: 1.5 dB
Features: Spkr. switch, blend, tone
control cancel.
Price: $349.95 (kit)
Panasonic SA -4000 FM only
Power Output: 60 W per chan.
THD: 0.1T10
Power Bandwidth: 20-30,000 J-tz
FM Sensitivity: 1.5 µ V
Capture Ratio: 1. dB
Features: Slide controls, 2 phono
inputs, tone control x -over switches,
auto tuning, preset controls behind
front panel, spkr. switch, blend
Harman-Kardon 630
Power Output: 30 W per chan.
THD: 0.1%
Power Bandwidth: 10-45,000 Hz
FM Sensitivity: 2.3 µV
Capture Ratio: 2.5 dB
Features: Dual power supplies, hi -
control.
Price: $919.00
filters, spkr. switch.
Price: $259.95
JANUARY 1972
39
www.americanradiohistory.com
New
Quadraphonic
Receivers
JVC 4VR-5414
Power Output: 20 W per chan.
Note that all these receivers have
built-in matrix circuits but will
also operate with four separate or
discrete signals. Power output refers
to each channel with all four driven.
w
THD: 0.5%
Benjamin R4x40
Power Output: 40 W per chan.
Power Bandwidth: 15-35,000 Hz
FM Sensitivity: 2.0 µV
Capture Ratio: 2.0 dB
Features: CD -4 matrix, 5 -position
tone control system, spkr. switch,
remote control jack.
Price: Not yet fixed.
THD: 0.5%
Power Bandwidth: 17-30,000 Hz
FM Sensitivity: 1.7 µV
Capture Ratio: 2.0 dB
Features: Spkr. switch, filters, sep.
rear spkr. controls.
Price: $450.00
Fisher 801
Power Output: 44 W per chan.
THD: 0.5%
Power Bandwidth: 20-25,000 Hz
FM Sensitivity: 1.7 µV
Capture Ratio: 1.5 dB
Features: Wireless remote control,
2 position matrix.
Price: $749.95
Lafayette LR440
Power Output: 25 W per chan.
THD: 0.8%
Power Bandwidth: 10-30,000 Hz
FM Sensitivity: 1.65 IS
Capture Ratio: 1.5 dB
Features: CBS matrix, spkr. switch.
Price: $378.60
4.,
Rotel RX-154
Power Output: 10 W per chan.
THD: 0.35%
Power Bandwidth: 35-30,000 Hz
FM Sensitivity: 5µV
Capture Ratio: 8 dB
Features: Matrix.
Price: Not yet fixed.
IIMZIIINIIIMIIrlIl
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Sansui QR-4500
Power Output: 27 W per chan.
THD: 0.5%
Power Bandwidth: 20-30,000 Hz
FM Sensitivity: 2.0 µV
Capture Ratio: 2.0 dB
Features: 3 -position matrix, spkr.
switch, filters.
Price: $579.95; Model QR500
(4x15W), $289.95
___1 _I11
i
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a
Scott 444
Power Output: 25 W per chan.
THD: 0.5%
Power Bandwidth: 25-20,000 Hz
FM Sensitivity: 1.9 µV
Capture Ratio: 2.5 dB
Features: Matix, spkr. switch, filters.
Price: $449.95
40
Pioneer QX-8000
Power Output: 20 W per chan.
'
THD: 1.0%
Power Bandwidth: 15-35,000 Hz
FM Sensitivity: 2.0 µV
Capture Ratio: 3.0 dB
Features: Phase-Shift and Quadra lizer matrixing, filters, spkr. switch.
Price: $499.95
AUDIO
www.americanradiohistory.com
,,
OUR 25th YEAR
JANUARY 1972
New Tuners
MIMITMOIRf+
.U
Z.
...
1
TEAC AT-100 (FM only)
FM Sensitivity: 2.0 µV
Capture Ratio: 1.5 dB
Separation, 1000 Hz: 40 dB
THD: 0.5%
AM Suppression: 50 dB
Tuning Indicator: 2 meters
Price: Not yet fixed.
CZ
THD: 0.02%
AM Suppression: 54 dB
Tuning Indicator: 2 meters
Features: Multipath indicator,
adjustable trigger control.
Price: $499.00
,
5
.....
me
+
;Ili-
Revox A76 (FM only)
FM Sensitivity: 1.0 µV
Capture Ratio: 1.0 dB
Separation, 1000 Hz: 40 dB
0
-_
Scott 433 (FM only)
FM Sensitivity: 2.0 RV
Capture Ratio: 1.8 dB
Separation, 1000 Hz: 35 dB
THD: 0.8%
AM Suppression: 70 dB
Tuning Indicator: Digital readout
Features: Card program or manual
selection.
Price: $549.90
CM
e
Nikko FAM 1200 (AM/FM)
FM Sensitivity: 1.5 µV
Capture Ratio: 1.5 dB
Separation, 1000 Hz: 25 dB
THD: 0.6%
AM Suppression: 45 dB
Tuning Indicator: 2 meters
Features: Headphone output with
level control, multipath indicator.
Price: $239.95
Pioneer TX -1000 (AM/FM)
FM Sensitivity: 1.7 µV
Capture Ratio: 1.5 dB
Separation, 1000 Hz: 25 dB
THD: 0.5%
AM Suppression: 55 dB
Tuning Indicator: Two meters
Features: 2 X-tal filters, output
socket for headphones with level
control.
Price: $279.95
0 Q
JVC 5109 (AM/FM)
FM Sensitivity: 1.7 µV
Capture Ratio: 1.7 dB
Separation, 1000 Hz: 35 dB
THD: 0.6%
AM Suppression: 55 dB
Tuning Indicator: Meter
Features: Provision for 4 -chan.
adaptor.
Price: $199.95
e
Ilki
IMMEME11
Standard TU -108 (AM/FM)
FM Sensitivity: 5.0 µV
Capture Ratio: 6 dB
Separation, 1000 Hz: 36 dB
THD: 1.1%
AM Suppression: 45 dB
Tuning Indicator: Meter
Features: AFC switch, built-in AM
antenna.
Price: $69.95
AUDIO
OUR 25th YEAR
--1,--f,...
2==
'-...L.U.V.L.Wilit.r.:
Dynaco FM -5 (FM only)
FM Sensitivity: 1.75 µV
Capture Ratio: 1.5 dB
Separation, 1000 Hz: 40 dB
THD: 0.5%
AM Suppression: 65 dB
Tuning Indicator: Meter
Price: $249.95
Marantz 120 (AM/FM)
FM Sensitivity: 2.3 IN
Capture Ratio: 1.6 dB
Separation, 1000 Hz: 42 dB
THD: 0.3%
AM Suppression: 65 dB
Tuning Indicator: Oscilloscope
Features: Scope display for multi path, center channel, separation,
phasing.
Price: $395.00
41
JANUARY 1972
www.americanradiohistory.com
IC Toue Wirst Generator
l'art In: Check Out and
Operationn
Walter Jung
we turn on the tone
burst generator, check it out,
and begin to put it to use. Note
the term "begin." The uses we'll cover
here are far from complete, and when
you finish your unit, you'll probably
think of some new ones too! But first
let's set it up and see that it does what
it is supposed to do.
peak clipping or spurious oscillation.
If this is true, reduce amplitude to 1V
Checkout and
Alignment Procedure
R26 for max sensitivity. Raise signal
level to 10 V p -p and note that the
relative phase change of the square wave
is a minimum. This checks the limiter
and phase control circuits and Figs.
and 2 demonstrate the dynamic range.
Plug in IC 4 and check for a sharp.
clean 4 volt p-p signal at pin 3. Rise and
fall time should be 100 nanoseconds or
less, and there should be no trace of
oscillations or spurious glitches as phase
control R26 or the input level is changed.
Check for a negative 4 microsecond
pulse at pin 11 of IC 4. This pulse
should be clean and sharp with no
evidence of double pulsing. Check that
this same pulse is being applied to pin
of IC 5 and IC 7.
Now you may start the counters
operating by plugging in IC 7 and IC 8.
This check is very simple-look for a
two-times division in each binary with
an overall 16-times division for the set.
THIS MONTH
It is recommended that portions of
the unit be checked sequentially to aid
in pinpointing any possible trouble
areas. Build and check stage by stage,
this way you'll nail down any circuit
gremlins before they get a chance to
cause grief. Let's start with the power
supply.
Last month's Fig. 5 was the complete
power supply section. You may check it
for operation very quickly by removing
all loads before firing up and very
closely verifying your circuit's conformity with the schematic. Watch diode
and capacitor polarities and the index
tab on the 723 regulators. For the TO -5
type can, the tab is adjacent to pin 10.
When all is determined to be well.
install a fuse in the fuse holder and
monitor the d.c. voltage across C6. With
power applied it should rise to a positive
18-22 volts. The voltage across C7
should be the same with a negative
polarity. If these are OK, check the
± 12 V outputs across C12 and C13.
They need not be precisely 12 volts,
(±0.5 volt OK) but the a.c. ripple
should be low, less than lmV. Check the
+5 volt output at Q6 -Q7. This should
be between 4.5 and 5.5 volts.
If all the above tests are OK, you can
hook up power to the rest of the generator. But don't plug in IC4-IC8 yet.
The first stages to check are the input
buffer and the synchronizer, as we need
the timing signals to make things happen elsewhere. Apply a 10 V p -p, I KHz
sine wave to JI and check to see that
it is duplicated undistorted at ICI's
output. There should be no d.c. offset,
p -p.
Now check limiter stage IC 3 by
monitoring the junction of R36 and
R37. The wave form should appear
similar to Fig. 1, bottom trace. Rotate
fine phase control R26 and the duty
cycle of the square wave should shift.
Reduce signal to 50 mV p -p and "peak"
1
1
Not much can go wrong here save a
wiring error or sick chip.
Things start to get interesting when
next you fire up the timer circuits.
This operation demands some care. Set
S4 for the 1-10 microsecond range and
rotate Rt to minimum resistance. Insert IC 5 and check for a negative pulse
at IC 5 pin 6. Vary Rt from MIN to MAX
and verify a timing range from slightly
under 10 microseconds to slightly over
100 microseconds. A similar check can
be made of the remaining ranges,
progressing upwards in time until the
lóngest range is reached. If a range
should fall short of its maximum, pad
Ct with an additional capacitor until
the spread is reached. There should be
more than a 10-1 range with overlap
between adjacent ranges of S4. When
the pulse length of IC5 exceeds the
period of the input frequency (1 millisecond in this case), it will begin to
"drop" input pulses. Check to see that
this is in fact being done and the pulse
width is stable up to and after the point
where it drops the second trigger pulse
at pin 1.
In a similar manner IC6 can be
checked out and its timing ranges
verified. Set S4 for a range of 1000 is or
less and insert IC6. Check for a negative
pulse at IC5-3 and 4. The width of this
1
1
1
i
Fig. 1-Operation of limiter at low signal level. Upper trace is 1KHz input signal at 50 mV/cm; bottom is limiter
output at 2 V/cm; d.c. zero is second
line from bottom. R26 is set for symmetry and time base is 200 µS/cm.
2-Operation of limiter at high signal level. Upper trace is 1 KHz input
signal at 5 V/cm; bottom is limiter
output; same scale as Fig. 1. R26 is
unchanged from Fig. 1, as is time base.
Fig.
AUDIO
42
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
For $239.95 we think you deserve
something more than just another stereo receiver.
KLH introduces something more.
IHIlI1I1I111
IIIIIIIID:
MCIOEL FIF v - CINE
n1111lr111M111
Most stereo receivers
that cost between $200 and
$250 don't sound half bad.
Some even look kind of nice,
if not exactly sexy. And they
usually work more times
than not. Perhaps they can
best be described as predictably adequate.
To us, that doesn't
sound too thrilling.
We figure a couple of
hundred dollars or so entitles you to something
more. Something like our
new Model Fifty -One
AM/FM Stereo Receiver.
For one thing, it has big de-
1P1i411
pendable power; it'll drive
loudspeakers that leave
lesser instruments gasping.
looks more expensive than
similarly priced stereo receivers. And it feels more
expensive too. Each knob,
switch and sliding control
gives you a real sense of
authority. Stations literally
lock in when you turn the
dial. The controls are crisp
and flawless. No mushiness
here. Also, both the AM and
FM sections will pull in
stations you didn't even
know were on the dial. But
most important, the FiftyIt
One has the overall quality
that most people expect
from KLH. And you get it all
for just $239.95t including
walnut -grain enclosure
Make sure you see and
hear the Fifty -One soon. It's
at your KLH dealer now.
You'll recognize it immediately; it's the sexy one that
sounds great.
For more information
on the Model Fifty -One,
write to KLH Research and
Development, 30 Cross St.,
Cambridge, Mass. 021 39.
Or visit your KLH dealer
(
1
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$2.19 45
Check No. 42 on Reader Service Card
www.americanradiohistory.com
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Fig. 3-Operation of offset control R8.
Upper trace is correct setting with
switching occurring at negative peak,
OFF level equals 100% (or equal to oN
level). Lower trace shows incorrect
setting of R8 with d.c. level of OFF level
lower than oN level. Scales are 1 V/cm
vertical and 20 µS/cm horizontal,
input 10 KHz.
Fig. 4-Residual hum and noise of
tone burst generator with input shorted.
Scales are 1 mV/cm vertical, 2 mS/cm
horizontal.
Fig. 5-Residual crosstalk of generator
with gate OFF by switching to EXT with
no ExT input. Signal input is 10 V p -p
mV/cm vertical,
at
KHz. Scales are
500 AS /cm horizontal.
1
1
pulse should vary in a manner as was
described above for ICS's output. Run
through the ranges of S5 and check for
overlap and 10-1 range of Rt2. This
completes the synchronizer circuit
checkout.
At this point you should be able
to verify complete synchronizer operation by monitoring SYNC OUTPUT at J3.
In the COUNTED position of S2 you
should get a variable frequency square
wave from ' to 1/16 the input frequency as S3 is rotated from 2 to 4, 8,
and 16. In the DIRECT position of S3 you
should get a "squared up" version of
the input signal with phase adjustable
by S 1 and R26. In the TIMED position of
S2 you should get the variable pulse
length of IC5 effected by S4 and Rtl,
while S5 and Rt2 will determine the
spacing between pulses.
Now we are ready to check the switch
for operation. If everything is wired
correctly you may see a gated tone
burst at J4 already, but it may not yet
make proper sense. Rotate R5 (orr
level) to MINIMUM (max counterclockwise) and set R8 to the center of its
range. With a high gain d.c. coupled
scope or the lowest range on your
VTVM or VOM, set R3 for zero volts
d.c. at IC2 pin 2. This biases IC2 for
zero input d.c. offset. Then set R15 for
a output d.c. baseline of zero volts
observed at J4. Set Mode switch S2 to
COUNTED and Count Ratio S3 to 2.
With Override switch S6 in NORMAL
you should see a gated tone burst with
ON level equal to the INPUT level and
OFF level ZERO. Depress S6 down
momentarily and the OFF period should
fill in. The generator is now working
and all that now remains is to set R8 for
minimum offset. Bring up OFF level
control R5 until the p -p level during
the OFF level is equal to the ON p -p level.
You can reduce input level to p -p or
less and expand scope sensitivity to see
this effectively. Switch to the timed
mode and set S4 and Rt 1 to switch at
a peak of the sine wave. You will
probably see an offset between the
peaks like Fig. 3, bottom. Rotate R8
until this offset is nulled, as in the wave-
form directly above. Now you should be
able to operate R5 from MIN to MAX and
gradually "fill in" the OFF period of the
burst. At the maximum position of R5
the OFF level may be slightly over or
slightly shy of the ON level. If it is short
you can trim RE6 to a slightly lower
value to make up the difference. Once
this is done you should not have to adjust R8 or R3 again.
Now rotate R15 from MIN to MAX and
check for +5 volts of d.c. baseline
shift. Reset R15 for zero volts baseline
and adjust the input for 10 volts peak
output ON level. Load output with 500
ohms and check that waveform is undistorted. By either raising the input
further or shifting R15 plus or minus
you should see the Q4-Q5 output current limit at slightly above ±5 volts.
This completes the setup and checkout,
and the generator will now perform as
per the specification objectives listed
in Part I.
Operation
Now that you have your tone burst
generator operating, you will quickly
1
Fig. 6-Operation of COUNTED-DIRECT mode with 1 KHz input
at 10 V p -p. Upper trace is coarse phase 0 degrees with R26
centered, d.c. zero is second line from top. Lower trace is coarse
phase 180 degrees with R26 centered, d.c. zero is second
line from bottom. Scales are 5 V/cm vertical, 1 mS/cm horizontal.
become fascinated by the wide variety
of waveforms it can produce. Spend a
few minutes familiarizing yourself with
the operation of the controls. Run each
control in each mode through its range
and observe the effect on the output
waveform as you change the settings.
A few examples illustrating operation
are shown in the waveform photos.
These you should be able to reproduce
easily. All were taken with a Tektronix
545A scope with a type W plug-in.
Uses of the Tone Burst Generator
Much has been written on the various
uses of tone burst generators. Its main
Fig. 7-Operation of COUNTED -DIVIDE by 2 and 16 with input
KHz at 10 V p -p. Upper trace is 2 (1 ON, 1 OFF) at 1 mS/cm,
d.c. zero second line from top. Lower trace is 16 (8 ON, 8
OFF) at 2 mS/cm, d.c. zero second line from top.
1
44
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
Fig.
8-Operation of TIMED mode with override. Input is 10 V
pip at 10 KHz. Upper trace is 3 cycles ON, 4 cycles OFF, 50%
OFF level. D.c. zero is second line from top. Lower trace is same
input signal but overriden with S6. D.c. zero is second line
from bottom. Scales are 5 V/cm vertical, 100 µS/cm horizontal both traces.
Fig. 9-Operation of TIMED mode with high duty cycles. Input is 10 V p -p at 10 KHz, timing set for 99 cycles ON and 1
OFF. Upper trace is gated output at 2 mS/cm horizontal sweep
with OFF time intensified. Lower trace is the intensified portion
expanded to 50 µS/cm to show 1 cycle of OFF time. Vertical
scale factor for both traces is 5 V/cm.
Fig. 10-Operation of TIMED mode with low duty cycle.
Input 10 V p -p at 10 KHz. Timing set for 1 cycle ON, 99 OFF.
Upper trace is gated output at 2 mS/cm horizontal sweep
with olé time intensified. Lower trace is intensified portion expanded to 50 µS/cm to show
cycle of ON time. Vertical
scale factor is 5 V /cm for both traces.
Fig. 11-Using the tone burst generator as a variable frequency, variable duty cycle oscillator with logic level and variable output. Mode control set to TIMED, S4 and S5 on 1-10 mS
ranges, Rt1 and Rt2 adjusted for 5 mS. IC6 pin 8 jumper to J1
input. Upper trace is double exposure of J4 output at two
different settings on OFF level control. Vertical scale is 2V/cm
and d.c. zero is center of graticule. Bottom is J3 output (sync)
at 5 V/cm. Horizontal scale is 2 mS/cm for both.
12-Use as an oscillator with variable COUNT and variable
level in alternate group periods. Oscillation frequency as
set in Fig. 11, but output switching done in COUNT Mode 4.
ON for two periods, and OFF for two periods. OFF level is set to
50%, d.c. zero is bottom of graticule. Vertical scale is 2 V/cm,
Fig. 13-Tone burst with low duty cycle used to check a half
wave rectifier time constant. Four cycles of 10 KHz space
6.5 mS. Scales are 5 V/cm vertical and 1 mS/cm horizontal
for both scales. D.c. zeros are second lines from both top
and bottom respectively. Top is input to rectifier, bottom is
output.
1
Fig.
OFF
horizontal 5 mS/cm.
AUDIO
OUR 25th YEAR
JANUARY 1972
45
www.americanradiohistory.com
THE ADC 303AX
GIVES YOU
WHAT ANY OTHER
ADC SPEAKER
GIVES YOU...
flexibility is in the fact that it is a bridge
between steady state sinusoidal tests and
pulse or rectangular wave tests. It
produces a controlled transient waveform of wide usefulness in loudspeaker
tests, amplifier music power checks,
acoustic work, sonar work, testing of
filters and tuned networks, rectifier
response, meter ballistics, and many
others. These and other applications
are well covered by Skilling (2) (3) (4)
in the General Radio literature, and
more recently Annes (6) has illustrated
practical uses of the device. All of these
uses are well served by this version also,
as well as some more which will now
. the cleanest, most natural sound
for your dollars. Indeed, we believe you
will have difficulty finding a speaker
at any price which is significantly
superior for use under domestic
conditions.
This combination of economy and
excellence is achieved by the
hyper-critical matching of the separate
components that go to make up the
303AX System. The woofer, tweeter,
crossover, cabinet, even the grill cloth,
have been specifically developed to
compliment each other to produce the
finest possible performance for a
system of this size.
Gimmicks have been eschewed.
Instead, you have very smooth
response, wide dispersion and low distortion
all essential if you are
to be conscious of the music rather
than the speaker.
-
SPECIFICATIONS
...
Nominal Impedance
8 ohms
Response
37Hz to 20kHz± 3dB
in average listening room
High Frequency Driver
21/2"
viscous impregnated cone with 11/2"
Dia. effective radiating surface.
10" viscous
Low Frequency Driver
coated cone with a high compliance
suspension and long voice coil.
Midrange Switch
Approx. 3dB
change over the band from 200Hz to
...
...
...
...
2kHz.
Treble Switch ... Approx. 3dB change
over the band from 2kHz to 20kHz.
Enclosure ... Oiled walnut air -tight
cabinet 233/4" H x 13" W x 113/4" D.
Filled with controlled sound absorbent
material. Shipping weight approx.
37 lbs.
Price ... $110.00 suggested retail
(5% higher in West).
Write for further details about this
and other ADC speakers from
$50.00 to $160.00.
AUDIO
DYNAMICS
CORPORATION
PICKETT DISTRICT ROAD,
NEW MILFORD, CONNECTICUT 06776
be described.
The classic portrait of a tone burst is
a gated sinusoid. Although this is indeed a tone burst, the association of
only the sinusoid with burst testing is a
severe mental limitation of the techniques available. Any periodic waveform can be gated with this tone burst
generator-square. triangular, pulse.
saw-tooth-you name it. As a pulse gate
you can use the device as a variable
divider of ratios up to 100 with excellent
stability. You'll get a divided logic
compatible output from the J3 sync
output and a variable level output from
the main output with the added feature
of variable d.c. offset.
The output of this unit is intentionally
designed to drive IC logic stages as
well as linear amplifiers. The d.c. baseline offset may be used as one limit of
logic level and the OFF level control as
the other. In this manner logic stages
can be checked dynamically with no
further equipment. The current rating
of ± 10 mA allows several stages to be
driven without distortion of the voltage
waveform. And the fact that there is
complete control over the baseline,
level and polarity will allow it to interface with most popular logic families
such as DTL, TTL, RTL and ECL.
Thus the device can be used as variable
period digital word generator with the
ability to generate a wide variety of
output pulse shapes. An additional
feature beyond the division capability
is the variable OFF level. By using the
variability of the OFF level in conjunction with the baseline control, you can
simutaneously test the ON and OFF levels
of a logic stage for instance.
The flexibility of this instrument goes
beyond the division of an input waveform. You can use the timer circuits
as a variable frequency and duty cycle
oscillator. To do this it is necessary to
jumper IC6 pin 8 to the input JI. This
closes an oscillating loop through ICI,
IC3 and IC4 to IC5 and IC6. The ON
and OFF timers IC5 and IC6 serve as
independently variable timers which
comprise the two portions of an oscillating cycle. An 'example of this operation is shown in Fig. 11. Here the times
of IC5 and IC6 are set for equal lengths
of 5 mS, thus setting up a sytñetrical
100 HZ square wave. In Fig. 3 both logic
level and variable outputs are shown.
The variable output occurs from the
action of the square wave gating itself
ON and OFF, thus OFF level control R5
serves as a linear gain control. Since
there are no limitations on duty cycle
on the timers, you can generate pulse or
square waveforms over the entire range
of IC5 and IC6 timing circuits.
A variation on this is to set up a basic
oscillation with the timer, and switch
the output to COUNTED. This will give
an alternate pattern of ON-OFF levels.
The number pulses in a group are determined by the Count Ratio, and the OFF
level set by R5. An example of this is
Fig. 12, which shows the osciallation of
Fig. 11 gated by the dividers operating
as DIVIDE-BY -FOUR.
You may want to add an auxiliary
jack on the back connected to IC6 pin
8 to enable this hookup or wire in an
extra switch to perform the same function.
Obviously a description of the uses
of this tone burst generator could go
on and on. But at some point we have
to stop and turn the controls over to
you. It is probably a safe guess that
builders of this generator will discover
many more applications. Towards that
end we have included a list of background references which should be helpful both in general and for application
ideas. It will be interesting to hear of
the diversity of applications which
fellow AUDIO readers will find for this
tone burst generator. I'm sure we can
entice our friendly Editor into sharing
the best of them through the Letters
column. Have fun with your tone bursts
and Happy New Year.
Æ
REFERENCES
Jung, Walter G.. "The Monolithic Balanced
Modulator as a Versatile Audio Switching
Element," presented at 41st AES Convention,
October 8, 1971. AES preprint *816.
2. Skilling, J.K., "A Generator of AC Transients," General Radio Experimenter, Volume
40, *3; March, 1964.
of Sine J.K., "Generation
3. Skilling,
Squared Pulses With the Tone -Burst Generator,"
General Radio Experimenter, Volume 40, *3;
March, 1966.
4. Skilling, J.K., "Testing with Tone Burst
Signals," The Electronic Engineer, December,
1966. General Radio Reprint 130.
5. Kelly, Stanley, "Design of a Tone Burst
Generator," Journal of the Audio Engineering
Society, Volume 18, *4; August, 1970.
6. Annes, Tom, "14 Ways to Use R -E's Tone
Burst Generator," Radio Electronics, Volume
42, *8; August, 1971.
1.
AUDIO
46
Check No. 56 on Reader Service Card
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
The new ADC-XLM
Superb performance.
Lowest mass.
Unbeatable price.
And it's guaranteed for 10 years.
If you're like most audiophiles,
you've probably spent a great
deal of time, effort and money
looking for the "perfect"
cartridge.
We know what you've been
through. After all, we've been
through it ourselves.
That's why we're especially
enthusiastic about our newest
cartridge, the ADC-XLM. It does
everything a well designed
cartridge should do. It may not
be perfect, but we don't know of
any that are better, and few that
even come close.
Now, we'd like to tell you why.
'the lighter, the better.
To begin with, it is generally
agreed that the first
consideration in choosing a
cartridge should be low mass.
And as you may have guessed by
now, the LM in our model
designation stands for low mass.
Not only is the overall weight
of the ADC-XLM extremely
low, but the mass of the allimportant moving system (the
stylus assembly) is lower than
that of any other cartridge.
Translated into performance,
this means effortless tracking at
lighter pressures with
distortion.
In fact, used in a well
designed, low mass tone arm,
the XLM will track better at 0.4
gram than most cartridges at
one gram or more.
less
A new solution for an
old problem.
One of the thorniest problems
confronting a cartridge designer
is how to get rid of the high
frequency resonances common
to all cartridge systems.
Over the years, various
remedies have been tried with
only moderate success. Often the
cure was worse than the disease.
Now thanks to a little bit of
original thinking, ADC has come
up with a very effective solution
to the problem. We use the
electromagnetic forces generated
within the cartridge itself to
damp out these troublesome
resonances. We call this selfcorrecting process, "Controlled
Electrodynamic Damping;' or
C.E.D. for short.
And if it seems a little
complicated, just think of C.E.D.
as a more effective way of
achieving lower distortion and
superior tracking, as well as
extending frequency response.
Naturally, there's much more
to the new ADC-XLM, like our
unique induced magnet system,
but let's save that for later.
Guaranteed reliability plus.
At ADC we've always felt that
reliability was just as important
technical specification.
That's why we now guarantee
every ADC-XLM, exclusive of
as any
stylus, for a full ten years.
But this unprecedented
guarantee*involves something
more than just an assurance of
quality. It is also an expression
of our conviction that the
performance of this cartridge is
so outstanding that it is not likely
to be surpassed within the
foreseeable future.
And something more.
In addition to the superb
ADC-XLM, there is also a new
low mass ADC-VLM, which is
recommended for use in record
players requiring tracking
pressures of more than one gram.
The cartridge body is identical
for both units, and so is the
guarantee. Only the stylus
assemblies are different. Thus
you can start out modestly and
move up to the finest and still
protect your investment.
And that brings us to the
important question of price,
which we are happy to say is
significantly lower than what
you might reasonably expect to
pay for the finest. The suggested
list price for the incomparable
ADC-XLM is $50 and the
runner-up ADC-VLM is
only $40.
But no matter which low mass
ADC you choose, you can be
certain that they share the same
outstanding characteristics...
superb tracking, very low
distortion and exceptionally
smooth and extended
frequency response.
*We guarantee (to the original purchaser) this ADC cartridge, exclusive of stylus assembly, to be free of manufacturing defects for a ten year period from
the date of factory shipment. During that time, should a defect occur, the unit will be repaired or replaced (at our option) without cost. The enclosed
guarantee card must be filled out and returned to us within ten days of purchase, otherwise this guarantee will not apply. The guarantee does not cover
damage caused by accident or mishandling. To obtain service under the guarantee, simply mail the unit to our Customer Service Department.
TAudio Dynamios Corporation
Pickett District Road, New Milford, Connecticut 06776.
Check No. 47 on Reader Service Card
www.americanradiohistory.com
Equipment Profiles
Crown IC -150 Stereo Console
Telex 2 + 2 Tape Deck
Crown D-150 Stereo Power Amplifier
48
58
Dual 1218 Automatic Turntable
62
Acoustic Research AR -6 Loudspeaker
48
61
Crown IC -150 Integrated Circuit Stereo Console
Crown D-150 Dual Channel Power Amplifier
MANUFACTURER'S SPECIFICATIONS
IC-150:
Frequency Response, High Level: +0.6 dB, 3 Hz to 100kHz
with High Impedance Load. ±0.1 dB, 10 Hz to 20 kHz with
IHF load (100 KOhm in Parallel with 1000 pF). Phono: ±0.5
dB from standard RIAA response curve. Phase Response,
High Level: typically +1° to -7°, 20 Hz to 20 kHz with high
impedance load; +1° to -12°, 20 Hz to 20 kHz with IHF
load; Phono: typically ±5° additional phase shift, 20 Hz to
20 kHz. Total Harmonic Distortion: Essentially too low to
measure. Intermodulation Distortion: Less than 0.01 % at
2.5 volts out; typically less than 0.002% at 2.5 volts out and
less than 0.004% at 10.0 volts output. Hum and Noise, High
Level Inputs: 90 dB below rated output of 2.5 volts. (Typically, 100 dB below rated output with IHF "A" weighted
measurement). Phono Inputs: 80 dB below 10 mV input
(typically 0.5 µV). Gain, Hi Level Inputs: 20.8 dB ±0.2 dB.
Phono Inputs: Adjustable between 50 and 70 dB by means of
input level controls. Rated Output: 2.5 volts. Maximum
Output: 10 volts.
D-150:
Frequency Response: ±0.1 dB 20 Hz to 20 kHz at watt
into 8 ohm load; ±1 dB 4 Hz to 100 kHz. Power Output at
Clipping: Typically 100 watts rms per channel into 8 ohms,
180 watts rms per channel into 4 ohms. IHF Power Output:
Typically 210 watts rms into 8 ohm loads; 400 watts rms into
4 ohm loads. IM Distortion: Less than 0.01% at 75W.
THD: Less than 0.05% from 20 to 20,000 Hz, 75W.
Damping Factor: Greater than 200 up to kHz, 8 ohm load.
Hum and Noise: 110 dB below 75 watts rms (unweighted
band limited from 20 Hz to 20 kHz typically measures 119
dB). Load Impedance: 4 ohms or greater. Stable with all
speaker loads. Input sensitivity: 1.19 volts ±2% for 75 watts
into 8 ohm load. Input Impedance: 25 Kohms. Power
Response: +1 dB, 5 Hz to 20 KHz at 75 watts rms into 8
ohm load.
General Specifications
D-150:
Dimensions:17 in W. x 51/4 in. H. x 83/4 in. D., 19 -in. rack
mounting hardware available. Weight: 24 lbs. with front
panel. Price: $429.00: less front panel $399.00: optional
cabinet available.
Dimensions: 17 in. W. x 8% in. D x 61/2 in. H. Price:
$269.00; optional walnut cabinet, $33.00.
1
1
It is rare that the editors of AUDIO will review two important
pieces of equipment produced by the same manufacturer in
one issue. In the case of Crown's IC -150 stereo console and the
matching D-150 power amplifier, the two units are so ideally
suited to each other that to discuss one without fully evaluating its companion would be to do both an injustice. One of the
few other stereo power amplifiers we have ever measured
that could justifiably be used with the IC -150 control unit is
Crown's higher powered DC-300, and since not everyone will
even consider a 400 watt rms amplifier (or a price tag of
$685.00, found on the DC -300) the D-150, at $429.00 plus the
IC -150 át $269.00 form a combination at just under $700.00
that will appeal to the serious audio enthusiast who, very
simply, wants the best specifications that have ever been
incorporated in a preamplifier/amplifier component pair.
The IC-150 stereo console is shown in its optional walnut
cabinet (Model 5-D), but it can be shelf mounted nearly as
attractively without this optional extra. The brushed anodized
aluminum and black front panel is relatively simple in layout,
when you consider the flexibility of control functions afforded
by the thoughtful layout. The top portion of the panel contains
six knobs, two of which are really dual concentric types, and
two push -push buttons. The rotary knobs include a seven
position selector switch (two phono inputs, tuner, two auxiliary
inputs and two tape inputs), a volume control, a balance
control, a continuous control labelled PANORAMA and dual
concentric BASS and TREBLE controls. The PANORAMA control
acts somewhat like a MODE selector, except that its action is
continuous. When rotated fully counterclockwise, normal
stereo reproduction is afforded, with full separation. As you
rotate the knob towards its mid -position, left -right blending
takes place until a monophonic mix is achieved. Clockwise
rotation of this control beyond the center point begins to
48
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
LOUNGE
The sensational SWINGER -
LOUNGER streamlined
comfort that compares to
recliners selling for twice
the price!
1
Specially priced
195
Matching ottoman only $28.00
Sit Up
11411111b.481119111111P
Sit Back
Stretch Out
The Swinger -Lounger is customized to fit your every position,
every shift of weight. You'll be snugly cradled into a deep,
luxurious, foam -filled recliner that measures a full-size 24" wide,
42" high (Ottoman is 24" x 24"). The luxurious Swinger looks
rich, feels rich
but costs little. Order yours today!
.
.
10 DAY MONEY -BACK GUARANTEE!
MAIL THIS ORDEIR FORM TODAY!
Please send me the Swinger -Lounger and
matching ottoman priced at $99.95 for both
items, shipped freight collect (up to $9.00).
understand that if am not completely satisfied,
may return them in 10 days and my
money will be fulhy and promptly refunded.
Check Choice of Colors:
Burnt Orange [] Tan
Avocado
Black
I
.
E
E
LIFELIKE ANIMAL RUGS
I
I
Oxblood
Send me Animal Rug at $98.95 each
E Bear
White
Brown
Black
Tiger
Leopard
Name
Address
City
Elate
Signature
E Check or Money Order Enclosed
(Save Shipping Costs;
Charge Account No.
Name of Charge
American Exp-ess
n
Diners Club
Executive Discount Shop,2ing Service
1309 Cherry St. Phila Pa 19107
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Zip
switch. The two push-push buttons introduce loudness -compensation and serve to by-pass the tone controls when absolutely
flat response is desired. The lower portion of the panel contains five rectangular push buttons which are also of the
"push -to-make. push -to -break" variety and control such functions as TAPE and TAPE 2 monitoring, low frequency filtering,
high frequency filtering, and power on/off.
As can be seen in Fig. 1, all rear panel connections are made
in a horizontal plane, but the designations are printed on the
vertical back wall, making them easy to read. This arrangement
has the additional advantage of avoiding any protrusions from
the back of the unit. Starting at the left of the rear panel, we
see an a.c. line fuse followed by five convenience a.c. outlets
(of which four are switched and one, intended for your phono
turntable or changer, is unswitched). A pair of terminal posts
come next, and these are for the optional connection of a remote electronic muting switch, which will be described later.
There follow pairs of main and tape output jacks, pairs of
tape input jacks and the necessary auxiliary, tuner and phono
input jacks. The latter are associated with screwdriver -type
level adjustments, which are to be set according upon your
restore stereo separation, this time in a reverse sense (that
is, left and right channels become reversed) until, at the
extreme clockwise position, full separation is restored. Thus,
this one cleverly conceived control offers the advantages of a
true BLEND control (a much needed feature which was popular
on some equipment in the early days of stereo but which for
some obscure reason was dropped from components more
recently) plus the needed features of a conventional MODE
Fig.
Fig.
1
1
panel of the Crown IC -150
-Rear
2-View from
cartridge output.
Figure 2 shows the deceptively simple looking innards of the
IC-I50. All major components of small dimensions are
mounted on glass (G-10) printed circuit board which is firmly
supported mechanically. The magnetically shielded power
transformer can also be seen over to the extreme right of the
photo. Figure 3, taken from Crown's instruction manual, is
a signal flow diagram showing the sequence of events that an
input signal undergoes from the input jacks to the outputs.
It should be noted, by the way, that the output impedance of
the IC -150 is 600 ohms and, if terminated in that impedance
(as would be the case in professional use), it will deliver a
maximum output of 5 volts. With high impedance terminations
(as, for example, when used with the matching D-150 power
amplifier) maximum output will be as high as 10 volts rms.
The phono preamp circuit board contains a total of nine
above the Crown IC -150
TAPE OUT
TREBLE
CONTROL
TAPE
2
TAPE
1
AUX
AUX
94. -
'-Q'-
2
1
TUNER
PHONO
PHONO
AUX
1
AUX
2
TAPE
TAPE
1
2
MONITOR
FILTER
CONTROL
LOUDNES
COMPENSATION
2
1
Fl
13-I!J
z
LEFT CHANNEL'
TUNER
LEVEL
INPUT
- -á2I
r ól
- --`INPUTSYPHONO
LOW
SELECTOR
SWITCH
RIGHT CHANNELS
PHONO
TAPE
23-
'INPUT
I
EDBACK
LEVELICONION L
F
LEVEL CONTROL
Ic=j1I>I-
EDBACK
F
121
EQUALIZATION &
L VEL CONTROL
GAIN=5O.7Odb)
---=I--
I
SELECTOR
SWITCH
á
II
II
gl
bi
El
JI;
ól
1
1
l
i
1
1
I
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si
IC
AMP
J HIGH
EXTERNAL
I
MUTE
li`ILTER
zl
MAIN
PAN
-CONTROL
l
.
BASS
CONTROL
1(
II
-1
;>1J1
PHONO
PREAM
BALANCE
CONTROL
-----o"IoImI
ÑÚlml
=1
1
(GAIN=2O.8db)
ám,J.
MUTER
2h OUT
----C, OUTPUTS2^-23 MAIN
i
OUT
1
=I/
I
IC
AMP
LOUDNESS
COMPENSATION
IÌ
lI.
HIGH
FILTER
JI
iBASS
JCONTROLrr
1
TRETRE
CONTROL
-J
TAPE OUT
SWITCHED
POWER TRANSFORMER
OUTLETS
POWER
POWER
SWITCH
SUPPLY_L_
LOW
UNSWITCHED
OUTLET
ENERGY
SUPPLY
REGULATED
+18 VOLT
SUPPLY
REGULATED
-18 VOLT
SUPPLY
N
AC LINE
MUTING RELAY
AMPLIFIERS
Fig.
3-IC-1 50 signal flow diagram.
AUDIO
50
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
The magnificent Seven
We've been hearing unsolicited rave reviews from soundmen across the
country concerning our seven ingeniously versatile problem -solving audio
control components (1) M68 Microphone Mixer, vanguard of the low-cost,
high-performance portable mixers; (2) M68 -RM Mixer, with built-in reverb
for vocalists and special effects; (3) M67 Mixer, the trail -blazing low-cost
professional mixer; (4) M63 Audio Control Center, that gives you variable
response shaping; (5) M62V Level-Loc, the audio level controller that automatically limits output level; (6) M688 Stereo Mixer, made to order for stereo
recording and audio-visual work; and finally, (7) M675 Broadcast Production
Master, that teams up with our M67 to give a complete broadcast production
console (with cuing) for under $325. Write for the new Shure Circuitry catalog
that shows them all:
Shure Brothers Inc.
222 Hartrey Ave., Evanston, Ill. 60204
www.americanradiohistory.com
r
Check No. 51 on Reader Service Card
We believe the
Heathkit AR -1500
to be the world's finest
stereo receiver.
The experts
seem to agree.
"The AR -1500 is the most powerful and sensitive receiver we have ever measured ..."
- JULIAN HIRSCH, Stereo Review.
"... a stereo receiver easily worth twice the cost (or perhaps even more) ..."
- Audio Magazine.
"Great new solid-state stereo receiver kit matches the demands of the most golden of golden ears ..."
- Radio Electronics.
The Heathkit AR -1500 AM/FM/FM-Stereo Receiver ... 349.95* (kit, less cabinet)
www.americanradiohistory.com
Mr. Hirsch goes on to say: "The FM tuner section of the AR 1500 was outstandingly sensitive. We measured the IHF sensitivity at 1.4 microvolts, and the limiting curve was the steepest
we have ever measured ... The FM frequency response was
literally perfectly flat from 30 to 15,000 Hz ...Image rejection was over 100 dB (our measurement limit) ...
"The AM tuner was a pleasant surprise ... It sounded very
much like the FM tuner, with distinct sibilants and a quiet
background, and was easily the best -sounding AM tuner we
have had the pleasure of using...
"... all input levels can be matched and set for the most effective use of the loudness compensation. This valuable feature
is rarely found on high-fidelity receivers and amplifiers...
"The phono equalization was perfectly accurate (within our
measuring tolerances) .. The magnetic phono-input sensitivity was adjustable from 0.62 millivolt to about 4.5 millivolts,
with a noise level of 66 dB, which is very low ... When
properly set up, it would be impossible to overload the phono
inputs of the AR -1500 with any magnetic cartridge...
"... it significantly bettered Heath's conservative specifications. Into 8 -ohm loads, with both channels driven, the continuous power at clipping level was 81.5 watts per channel.
Into 4 ohms it was 133 watts per channel, and even with 16 ohm loads the receiver delivered 46.5 watts per channel.
Needless to say, the AR -1500 can drive any speaker we know
of, and with power to spare...
"At 1,000 Hz, harmonic distortion was well under 0.05 per
cent from 1 to 75 watts per channel ... The IM distortion was
under 0.05 per cent at levels of a couple of watts or less, and
gradually increased from 0.09 per cent at 10 watts to 0.16 per
cent at 75 watts ... The heavy power transformer is evidence
that there was no skimping in the power supply of the AR 1500, and its performance at the low-frequency extremes
clearly sets it apart from most receiver's...
"Virtually all the circuit boards plug into sockets, which are
hinged so that boards can be swung out for testing or servicing without shutting off the receiver. An 'extender' cable
permits any part of the receiver to be operated in the clear
even the entire power -transistor and heat -sink assembly! The
245 -page manual has extensive tests charts that show all voltage and resistance measurements in key circuits as they should
appear on the receivers built-in test meter...
"With their well-known thoroughness, Heath has left little to
the builder's imagination, and has assumed no electronic
training or knowledge on his part. The separate packaging of
all parts for each circuit board subassembly is a major boon...
"In sound quality and ease of operation, and in overall suitability for its intended use, one could not expect more from
any high-fidelity component."
-
-
From the pages of Audio Magazine:
.. the AR -1500 outperforms the near -perfect AR -15 in almost every important specification...
"The FM front end features six tuned circuits and utilizes
three FETs, while the AM RF section has two dual -gate
MOSFETs (for RF and mixer stages) and an FET oscillator
stage. The AM IF section features a 12 -pole LC filter and a
broad band detector. The FM IF section is worthy of special
comment. Three IC stages are used and there are two 5 -pole
LC filters...
"... IHF FM
sensitivity ... turned out to be 1.5 uV as opposed
to the 1.8 uV claimed. Furthermore, it was identical at 90
MHz and 106 MHz (the IHF spec requires a statement only
for IHF sensitivity at 98 MHz but we always measure this
important spec at three points on the dial). Notice that at just
over 2 microvolts of input signal S/N has already reached 50
dB. Ultimate S/N measured was 66 dB and consisted of small
hum components rather than any residual noise. THD in
Mono measured 0.25%, exactly twice as good as claimed!
Stereo THD was identical, at 0.25%, which is quite a feat...
.. the separation of the multiplex section of the AR-1500
reaches about 45 dB at mid-band and is still 32 dB at 50 Hz
and 25 dB at 10 kHz (Can your phono cartridge do as well?)
"The real surprise came when we spent some time listening
to AM ... This new AM design is superb. We still have one
classical music station that has some simultaneous broadcasting on its AM and FM outlets and that gave us a good opportunity to A -B between the AM and FM performance of the
AR -1500. There was some high-frequency roll -off to be sure,
but BOTH signals were virtually noise-free and we were hard
pressed to detect more THD from the AM than from the FM
equivalent. Given AM circuits like this (and a bit of care on
the part of broadcasters) , AM may not be as dead as FM
advocates would have us believe!...
"Rated distortion [0.25%] is reached at a [continuous] power
output of 77.5 watts per channel with 8 ohm loads (both
channels driven). At rated output (60 watts per channel)
THD was a mere 0.1 % and at lower power levels there was
never a tendency for the THD to `creep up' again, which indicates the virtually complete absence of any 'crossover distortion' components. No so-called 'transistor sound' from
this receiver, you can be sure. We tried to measure IM distortion but kept getting readings of 0.05% no matter what we
did. Since that happens to be the 'limit' of our test equipment
and since the rated IM stated by Heath is 'less than 0.1% at
all power levels up to rated power output' there isn't much
more we can say except that, again, the unit is better than the
specification we just don't know how much better...
"As for the amplifiers and preamplifier sections, we just
couldn't hear them and that's a commendation. All we
heard was program material (plus some speaker coloration,
regrettably) unencumbered by audible distortion, noise, hum
or any other of the multitude of afflictions which beset some
high fidelity stereo installations. The controls are easy to use
and quickly become familiar...
"As always, construction instructions are lucid enough for the
inexperienced kit-builder and there is enough technical and
theoretical information to satisfy even the most knowledgeable audio/ RF engineer."
-
-
And Radio Electronics had this to say:
"As you know, the original, the AR -15, has been widely acclaimed as one of the very best stereo receivers that has ever
been made. Therefore, it's hard to imagine that anyone has
gone ahead and built a better one. But spec for spec, the AR 1500 is ahead of the AR -15..."
Kit AR -1500, less cabinet, 53 lbs.
349.95*
ARA -1500-1, walnut cabinet, 8 lbs.
24.95
See and hear the new AR -1500 at your nearest Heathkit Electronic Center ... order direct from the coupon below ... or
send for your free Heathkit catalog.
HEATHKIT ELECTRONICS CENTERS
HEATH KIT
ARIZ.: Phoenix, 2727 W. Indian School Rd.; CALIF.: Anaheim, 330 E.
Ball Rd.;: EI Cerrito, 6000 Potrero Ave.; Los Angeles, 2309 S. Flower
St.; Redwood City, 2001 Middlefield Rd.; San Diego (La Mesa), 8363
Center Dr.; Woodland Hills, 22504 Ventura Blvd.; COLO.: Denver,
5940 W. 38th Ave.; FLA.: Miami (Hialeah), 4705 W. 16th Ave.; GA.:
Atlanta, 5285 Roswell Rd.; ILL.: Chicago, 3462-66 W. Devon Ave.;
Downers Grove, 224 Ogden Ave.; KANSAS: Kansas City (Mission),
5960 Lamar Ave.; MD.: Rockville, 5542 Nicholson Lane; MASS.: Boston (Wellesley), 165 Worcester St.; MICH.: Detroit, 18645 W. Eight
Mile Rd. & 18149 E. Eight Mile Rd.; MINN.: Minneapolis (Hopkins),
101 Shady Oak Rd.; MO.: St. Louis, 9296 Gravois Ave.; N.J.: Fair
Lawn, 35-07 Broadway (Rte. 4); N.Y.: Buffalo (Amherst), 3476 Sheridan Dr.; New York, 35 W. 45th St.; Jericho, l.l., 15 Jericho Turnpike;
Rochester, Long Ridge Plaza; OHIO: Cincinnati (Woodlawn), 10133
Springfield Pike; Cleveland, 5444 Pearl Rd.; PA.: Philadelphia, 6318
Roosevelt Blvd.; Pittsburgh, 3482 Wm. Penn Hwy.; TEXAS: Dallas,
2715 Ross Ave.; Houston, 3705 Westheimer; WASH.: Seattle, 2221
Third Ave.; WIS.: Milwaukee, 5215 Fond du Lac.
HEATH COMPANY, Dept. 41-1
Schlumberger
--1
Benton Harbor, Michigan 49022
Enclosed is $
by return mail.
Enclosed is
cabinet for
$
plus shipping. Please send my
AR -1500
plus shipping for ARA -1500-1 walnut
AR -1500.
Please rush my free Heathkit Catalog.
FREE
scribes
CATALOG...deAR -1500,
plus over
350 other fun -to -build
home and hobby kits. Mail
coupon or write Heath
Company, Benton
Name
Address
City
Harbor,
Mich. 49022.
State
Zip
Prices & specifications subject to change without notice.
'Mail Order Prices; F.O.B. Factory
HF -255
L.
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www.americanradiohistory.com
Ll
MAIN OUTPUTS
14MHY
LEFT CH.
AUDIO
1
SW7
R47
2.7M
2
C38
HI
68NF
F
II
FROM
RIGHT
L
T
CHANNEL
E
-moo
RI
3053
TO
RIGHT CHANNEL
1
B+
RELAY
ENERGIZED
18V
Q7
EXTERNAL
2961
transistors (four per channel plus one voltage regulating
transistor) and all resitors involved in the equalization feedback circuits are 1% tolerance components while critical
capacitors have a tolerance of 21/2%! The electronics of the highlevel input amplification circuits is built around two IC's,
each of which contains the equivalent of 22 transistors and 14
diodes. In addition, there are 13 more bipolar transistors (nine
of which are used in the phono preamp stages), one FET
(field effect transistor), two zener diodes and eight diodes.
A partial schematic of the external muting circuit is shown in
Fig. 4. When power is initially applied to the IC -150, the
muting relay contacts tie the output to "ground." The muting
relay remains unenergized until an R-C circuit charges and
turns on the FET, which in turn energizes the relay and removes the short from the output. This process takes about five
seconds, during which any turn -on transients are permitted to
die out before the speakers are connected to the circuit. As
can be seen in Fig. 4, removal of the "short" across the external
mute terminals opens the emitter circuit of Q7 and prevents the
relay from ever becoming energized. Thus, a remote simple
SPST switch can serve to mute the system at any time from the
comfort of your easy chair.
MUTER
R50
470
Electrical Measurements
Fig.
4-Partial schematic of the muting circuit
IC-1
50.
in
the Crown
rFREQUENCY RESPONSE
.r
'
FULL
BASS
BOOST
FULL
T
80051
E5
BE
11
5
R
+5
LOA
HIGH
FILTER
FILTER
-
o
-10
FULL
BISSCUT
Io
FULL
TREBLE
CUT
-15
ION
I1X1
FREQUENCY -
dio
Ns
Fig. 5-Frequency response, tone control range, and filter
characteristics of the Crown IC -150.
We had no trouble plotting frequency response and tone
control action (shown in Fig. 5), nor was filter response a problem (see same Fig. 5). Loudness contours are shown for various
settings of the volume control when the "loudness" switch is
depressed (see Fig. 6). We were able to measure hum and noise
levels of approximately -93 dB below 2.5 volts output and
equivalent phono noise (phono inputs shorted) at about .50
microvolts and to confirm RIAA equalization as being as close
to perfect as our interpolation of fractions of a dB on our
expanded scale a.c. VTVM would permit. However, when it
came time to measure IM and THD, our test setup proved to
be completely useless. As stated in previous reviews, we are
rather proud of our new test equipment lower limits of 0.03%
THD and 0.05% IM, but of what use are these new pieces of
equipment when we are confronted with an IM figure (for
10 volts output) of 0.002%? In the interest of a complete report,
however, we present Fig. 7, which is nothing more than a plot
of the IM figures which appeared on the individual test sheet
that accompanied our Model IC -150. Please read the scales
carefully,. as they are deliberately expanded beyond anything
we normally show and, above all, feel free to take Crown's
word for it, as we humbly do.
We shall reserve comment on our listening tests until after
the discussion of the D-150 companion amplifier, since, as
o
.020
-10
.018
-20
.016
.014
-30
.012
-40
.010
- 50
.008
-60
.006
.004
.002
10
100
1K
10K
0.1
I
OUTPUT
Fig. 6-Loudness-contour characteristics of the IC -150 at
various settings of the volume control with loudness circuits
ON.
- VOLTS r.m.s.
7-IM distortion of the IC -150 as measured by the manu facturer. (Note the expanded scale of percentages.)
Fig.
54
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
stated, all listening tests were done using both products hooked
up together.
D-150 Power Amplifier
The D-150 dual power amplifier's optional front panel and
walnut enclosure, again, need not be used except as dress items,
since the power amplifier is fully enclosed as it comes and, in
our view, somewhat more awe inspiring at that, as shown in
Fig. 8. The major cover shown in the photo (which contains the
serial identification label, etc.) is removable and, when removed, discloses the massive power transformer, as seen in Fig.
9. The photo also shows the pair of input jacks (phone jack
type), above which are located a pair of screwdriver input level
adjustments, and the speaker output terminals which utilize
standard '/,-in. center -to -center MDP terminals intended for
the dual banana plugs normally associated with test equipment
interconnecting cables. These are supplied in the accessory
bag with each unit. Also included in the accessory bag are in line fuse receptacles and cables which are strongly recommended as the right way to connect from amplifier output
terminals to speaker systems, in the interest of speaker protection. A handy nomograph in the very complete instruction
manual helps you to select the proper fuse size for your
speakers based upon their impedance and their peak music
power rating.
An "underneath the chassis" view of the D-150 is shown in
Fig. 10 which discloses the driver and output transistors. Input
stages and associated components are located on a p.c. board
which cannot be seen in this view. The D-150 has two direct
coupled amplifier circuits which employ a dual IC amp and
silicon transistors in all amplifier stages. As Crown explains
in their instruction booklet, the dual IC op -amp used is of
extremely low noise type and has a large gain -bandwidth. As
a result of its use as an input voltage amplifier, a maximum
amount of feedback can be applied with resultant reduction
of distortion to previously unattainable low values. At a typical
full output of 75 watts (8 ohms), IM has been measured by
Crown as 0.002%. By implication, THD might be expected to
be approximately 0.0005% which neither Crown nor we could
legitimately measure.
The output stages are essentially in a quasi -complimentary
format. In this version of an output circuit, however, the driver
transistors carry the bias current, while the output transistors
serve only as boosters. The output transistors "sense" when the
driver transistors are delivering significant current to the direct
coupled loads and then takeover and deliver the required large
load currents.
The output circuit is protected by a V-I (volt-ampere) limiter
which limits the drive to the output configuration whenever
the output transistors are overloaded and acts instantly to relieve the overload, acting only so long as the overload exists.
In addition, a thermal switch is mounted on the chassis surface
which protects the amplifier against insufficient ventilation.
If it becomes too hot, a.c. power to the amplifier will be interrupted until the temperature falls back to a safe level, at which
time power is automatically restored. The excellently written
and organized instruction manual details additional protection
schemes which the user might incorporate external to the
amplifier but these are primarily directed at speaker protection,
since the amplifier itself is deemed "fail safe" under any conditions. Positive and negative power supplies (±45 volts) permit direct coupling to the loudspeaker and the voltage offset at
the point of connection is guaranteed to be less than 10 mV.
Filtering of each of the supplies is by means of a 9400 µF, 50
volt capacitor of massive proportions. The power transformer,
incidentally, is suitable for 240 volt or 120 volt applications
and is safe at any power line frequency from 50 Hz to 400 Hz.
AUDIO
OUR 25th YEAR
Fig. 8-D-150 amplifier with decorative panel and walnut
enclosure removed.
Fig.
9-Close up of the
D -150's
power transformer and one
filter capacitor.
Fig. 10-The D -150's entire chassis acts as
the driver and output transistors.
a
heat sink for
0
-1
-3
IN
100
ION
100K
FREQUENCY - !h
Fig. 11-Frequency response at
D-1 50.
JANUARY 1972
1
watt rms, 8 -ohm load of the
55
www.americanradiohistory.com
(clipping actually occurred at about 103 watts per channel, both
channels driven, 8 ohm loads) extended to below any frequency
we could measure (at 5 Hz, full power output was still obtained)
and up to at least 30 KHz. A graph of this "straight line" is
shown in Fig. 12. Hum and noisg were measured at -120 dB
with reference to 75 watts rms output, 8 ohm loads and is an
unweighted reading (full 20 Hz to 20 kHz bandwidth). For
those interested in startlingly small numbers, this means that
the hum and noise power contribution to the loudspeakers is
75 x 10-'0 watts! (You may prefer to call this 75 pico -watts,
or 0.000000000075 watts!) The real point is, YOU CAN'T
HEAR IT-even with your ear glued to an efficient speaker
REFERENCE. I dB. ß WATTS'CN.
RIBS, BONN LOADS, BOTH CHANNELS
DRIVEN
1001
ICH
,ºFPUEric
Fig.
-i
12-Power response, D-150.
0.02
TYPICAL INTERMOOULAT
ION DISTORTION
0.01
160
0
TEST
INSTRUMENT
RESIDUAL
0.02
,an
0.001%
(TYPT
0
0.01
An
0.01
0.1
1
10
500
ID0
POKER OUTPUT (WATTS)
`
I
Fig. 13-IM distortion characteristics, D-150. (Supplied by
the manufacturer.)
A
wfil
ár
B
T.ae .
..M:i
.
- 11rr. r
1111111111111110i11111111111
1::111E
C
-
:
D
14-Square wave presentations, A, output of IC-150 with
20 Hz applied; B, output of IC -150 with 20 KHz applied;
C, output of IC -150 and D-150 with 20 Hz applied, and D,
output of IC -150 and D-150 with 20 KHz applied. (Note that
in all cases upper trace is signal source for comparison
purposes to output waveform in lower trace.)
Fig.
D-150 Measurements
Frequency response of the D-150 amplifier is plotted in
11. The -1 dB point (reference
watt, 8 ohm loads) was
reached at 5 Hz on the low end and at 75 kHz at the high end.
Power response based upon 75 watts output per channel
Fig.
1
system.
As for THD and IM measurements, we were again faced with
the problem of test equipment. If Crown's claim of a theoretical
THD of 0.0005% is correct (and we have no reason to doubt it),
then we, along with Crown, have no way to measure it with
presently available equipment. Evidently Crown does have an
IM Meter capable of reading down to 0.001% and therefore
presents a graph of IM versus power output which is reproduced in Fig. 13. Note that at 100 watts per channel into 8 ohm
loads, IM distortion is approximately 0.005% and at 10 milli watts power output (where any cross -over distortion would
certainly show up if it were present), IM measured by Crown is
just about 0.01%!
A series of square wave photos were taken for both the
IC-150 and the D-150 plus the IC -150 (operating together).
These are presented in Fig. 14 with explanatory captions for
each condition of measurement. The important thing to remember here is that the upper trace in each photo is our signal
source while the lower trace is, in all cases, the output as
observed from the IC -150 or the D-150. Thus, while not all the
observed waveforms are perfectly "square," this arises from
the fact that our source waveform is not always square either.
Notice, therefore, how closely the output always resembles the
input waveform at all frequencies and conditions shown.
Fig. 15 simply represents the condition observed when the
amplifiers are driven to clipping levels. At the moment the
photo was taken, total power output was approximately 110
watts rms per channel and since both channels were being
driven, the amplifier was pumping out about 220 watts of
power into our purely resistive loads. Since our resistive loads
used in all testing are rated at 100 watts each, we did not keep
this up for more than the time required to set up the camera
and take the 'scope photo.
Listening Tests
All our listening tests were done using the IC -150 and D-150
as an operating pair of components. Obviously, our speakers
(which are low efficiency types selling at around $150.00
apiece) are the limiting factor in any listening tests using equipment such as this, but somehow, a new sense of transparency
seemed evident. We know that this was not psychological
projection because we brought in several experienced listeners
who were not told the make or model of amplifier and preamplifier being used. Without exception, all these observers
told us that these particular speakers (with which all were
familiar) had "never sounded that good before. Now, we
sincerely doubt if the IM figures of under .01% could be audibly
interpreted as sounding better than, say 0.1% (which competitive equipment often achieves). Perhaps the unusually high
damping factor (over 200 at all frequencies below 1000 Hz) was
responsible for the audible difference. We're really not sure.
This much we do know, however: We monitored the signal
delivered to our speakers and there were times when peaks
of 90 watts were repeatedly delivered to the voice coil terminals. At all times the music was absolutely devoid of any audible
distortion. We also discovered how important choice of source
material becomes when you're dealing with equipment that is
56
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
so perfectly "clean" in its reproduction capabilities. Evidently,
less perfect amplifiers can often "mask" the deficiencies of
certain types of poorly recorded material (we're speaking primarily of discs). There was, unfortunately, no single source of
program that could fully utilize the dynamic range inherent
in the IC-150/D-150 combination. That is, any signal source
(FM, phono, tape) we tried invariably resulted in reproduced
noise and/or hum that was greater than the inherent noise
and/or hum which we didn't hear when listening to the equipment alone, with similar gain settings. If that sounds discouraging or suggests the question, "why buy something this good?",
bear in mind that over the last decade, tape dynamic range, for
example, has been improved by at least 10 dB or more. If such
trends continue, it may not be long before you'll be able to
feed a signal source to this superb preamplifier and amplifier
that is as good as they are. If you want the very best control
chassis and power amplifier we've ever tested in this power
class and can afford the price, our endorsement of the Crown
IC-150 and D-150 is completely given without any reservations
(unless, of course, you feel you need MORE power, in which
Leonard Feldman
case there's always the Crown 300!)
Fig. 15-Scope photo of clipped 1 10 watt rms signal (per
channel) from the D-1 50 shows perfect symmetry of clipping
and no evidence of "power supply collapse."
Check No. 57 on Reader Service Card
Looking at Fig.
1,
we see a digital counter on the left and
just under this is the speed change lever. On the right is the
ON-OFF, STANDBY, and PLAY Switch, and under that is a similar
switch controlling rewind direction. In the center is a pilot
light which indicates whether power is on. Figure 2 shows the
tape head and capstan, and Figure 3 shows the view from
underneath. Note the large, dynamically balanced flywheel
which weighs two pounds!
Measurements
Telex-Viking Quad/Sonic 2 + 2
MANUFACTURER'S SPECIFICATIONS
Speeds: 71/2, 33/4, 17/8 ips. Motors: Three, induction type.
Controls: Directional levers for OFF, STANDBY, and PLAY, and
for REWIND, STOP, and FAST FORWARD. Speed selector. Playback Frequency Response: 40 to 18,000 Hz ± 3 dB at
7Y2 ips. S/N Ratio: 50 dB. Crosstalk: 55 dB at 1000 Hz.
Head: Four -channel, in line, compatible for two or four channel
play. Wow and Flutter: Less than 0.2% at 71/2, 0.25% at
33/4. Output: 1.4 mV at 1000 Hz. Counter: Four digit, pushbutton reset. Brakes: Electro-dynamic. Finish: Black and silver
trim in walnut base. Size: 11 by 16Y2 by 61/4 inches. Price:
$249.95, with take-up reel, four patch cords, and ground
The frequency response curves are shown in Fig. 4. Ampex
standard tapes were used for the 33/4 and 71/2 ips speeds but
the response at 17/8 ips was made with a tape made on a Tandberg recorder. It will be noted that very little, if any, treble
boost is necessary for playback compensation and a response
up to 20 kHz at 33/4 and 71/2 ips should be easily realized with
low distortion. It must be remembered that almost unlimited
treble boost can be used to compensate for poor heads-at
the expense of high distortion and poor signal/noise ratio.
This is why (in terms of frequency response) a $99.95 deck
can have the same specifications as one costing over $1000.00!
The head in the Telex 2 + 2 is a professional -grade type
made by Nortronics, which of course is not cheap. Output
from the 71 ips standard tape was 1.1 mV at 1000 Hz (10 dB
below operating level). No signal/noise measurements were
taken by us, as these will depend on the amplifier, matching,
equalization, and so on. Wow and flutter came out at 0.11%
at 71/2, 0.2% at 33/4, and just under 0.25% at 17/8 ips-better than
the rather conservative specifications.
cable.
The Telex Quad/Sonic 2 + 2 is a quadraphonic tape deck
intended for use with an amplifier which can also provide
the necessary equalization-in other words, output is taken
directly from the heads. No recording facilities are provided
but the 2 + 2 can also play two-channel stereo as the heads
are in -line quarter track. Three motors are used, all induction
types, and there is a choice of three speeds, 17/8, 33/4, and 71/2ips.
AUDIO
OUR 25th YEAR
Fig.
2-Showing the tape
JANUARY 1972
head and capstan.
57
www.americanradiohistory.com
Performance
On test, the 2 + 2 came well up to expectations. The controls, which are simple but functional, worked smoothly and
were extremely easy to use. Mechanical noise was low and
the electro -dynamic brakes were really positive. No four channel receiver or amplifier with tape head inputs was available so two Fisher 700 receivers were pressed into service, and
it was found that equalization was not far out. No actual measurements were made but the standard Vanguard VSS-1 quad-
raphonic demonstration tape certainly sounded well-balanced
with solid bass and silky -smooth treble. The Vanguard recording of the Mahler 9th was also most impressive. Some
conventional two -channel tapes were played, with every satisfaction. Summing up, the Telex 2 + 2 can be recommended for
the attention of those who want a relatively inexpensive deck
T.A.
for playback only.
-- 7-t/2
0
-5
- 10
-
15
-20
FREQUENCY -HE
Fig. 4-Frequency response at the three speeds.
STANDBY
OFF
REWIND
Fig.
Fig. 3-Underneath view.
10,000
1000
100
20
5-Close
STOP
PLAY
FORWARD
up view of some of the controls.
Check No. 58 on Reader Service Card
Dual Model 1218 Automatic Turntable
MANUFACTURER'S SPECIFICATIONS
Speeds: 331/3, 45, and 78 rpm; adjustable +3%.Platter
Diameter: 10% in. Maximum Tracking Error: 0.5 deg.
Wow and Flutter at 331/s rpm: 0.80%. Pivot -to-stylus
Distance: 81/4 in. Dimensions: 13 x 103/4 in., 2% in.
below motor board, 5 in. above. Weight: 10 lbs. Price:
$
139.50.
There are many locations for automatic record changers that
will not accommodate the larger units, such as the Dual 1219,
but the user still wants the same performance obtainable with
the top -of-the -line model, or as near that performance as
possible. And therein lies the advantage of the 1218, which is
very similar in performance, yet just a little smaller, and therefore can often be utilized in locations which preclude the use of
the larger model.
The 1219 was profiled in these pages in December, 1969,
and most of what was said in that profile could apply to the
1218. The newer-and smaller-unit still uses the two -ring
gimbel mounting for the tonearm, with the elastically damped
counterbalance which rotates on fine threads for fine balance,
once the coarse balance is set by positioning the counterbalance shaft for approximate balance and tightening the
thumb screw which keeps it in place. Stylus force is then set
by a calibrated dial which applies the desired force through
a long spiral spring which acts directly around the pivot of
the tonearm.
Adjacent to the arm mounting is a knob which controls the
amount of anti -skating force applied to the arm. The scale
associated with this knob is calibrated for both conical and
elliptical styli, with the graduations in black for elliptical styli,
and in red for conical ones-indicative of the almost unanimous acceptance of the elliptical in high -quality installations.
A hole in the chassis just in front of the arm mounting gives
access to an adjustment for varying the tonearm cueing height
over a range of 1/a inch. The bearings for the two degrees of
motion of the turntable are of the low -friction pivot type,
58
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
the bare Fax
Meet the Wall of Sound, the superspeaker from Fairfax. In fact, look
into it. What you see is what you hear,
and every feature is a performance
advantage.
Our unique multiple driver system,
for example. You can see the complex
electronics, but you'll have to hear
how it reproduces the widest possible
range of sound with less distortion than
ever before possible. Outperforming
speakers selling for two or three times
the price, this unique parallel series
network has crossover frequencies of
550, 1500, 5500 and 0000 Hz. And
that's range.
You can see the unusual height, too.
Because of it, the baffle board is so big
we call it the infinite baffle. You'll hear
that advantage in the fantastic sound
dispersion.
Then there's the unique "integrated
cyclone" labyrinth system. You can't
see it behind the speakers, but it's
responsible for our superspeaker's
remarkably low distortion, increased
bass and improved transient response.
To develop it, we redesigned the entire
principle of horn -loaded speakers for
side-to -side instead of front -to -back
expansion. It's just one example of the
engineering that makes the Wall of
Sound the ultimate in speaker systems.
You can put your money on that.
ships is available for the hi fi dealer
who wishes to provide his customers
with the utmost in value at any price.
cFA IRFA X
I
NDUSTRTES INC.
900 PASSAIC AVE. EAST NEWARK, N.J. 07029
We did.
A limited number of franchised dealer MORE IN THE 1972 FAIRFAX SUPERSOUND LINE
When it comes to more features and greater quality for
your dollar, we have the proof, model for model. To see
how an independent testing laboratory rates the Fairfax
line against other leading speaker systems, send for your
free, highly informative copy of our comprehensive test
report.
SPECIALLY FABRICATED
DOME TWEETERS
Two ultra -high frequency
dome tweeters for clean, true
highs-even with the highenergy harmonic structures
that go beyond audibility.
Listen to brushed cymbals.
SUPERIOR DIFFERENTIATION
Two 3'h" mid -high speakers,
perfectly balanced within our
complex system for the smooth
sound of clear, stable stereo
images that let you pick out one
instrument from another.
GREATER RESPONSE
Two 5" mid -range speakers for
twice the response in the area
most critical for "presence."'
No peaking. No "canned"
sound. But wait 'till you hear
those woodwinds.
MORE WOOFERS FOR YOUR MONEY
Six, yes, six heavy-duty 8"
woofers instead of the conventional single 12" or 15".
For good reason. True fundamental sound is reproduced
with greater efficiency and
less distortion with our
unique multiple driver design.
SIX SEPARATE SOUND CHAMBERS...
extending behind these three
ports make a difference you'll
have to hear to believe.
Check No. 59 on Reader Service Card
www.americanradiohistory.com
4
are found near the arm mounting
-coarse and fine counterbalance, stylus force, anti -skating,
and tonearm cueing height. Note record spindle for single play use-it rotates with the platter to avoid wearing the center
hole and to ensure concentricity.
Fig. 3-The right front of the chassis accomodates the three
most -used operating controls-the cueing lever, which
extends out of the photo at the upper right, the record size selector with positions for 7-, 10-, and 12 -in. records, and
the start -stop lever. The hole above the record -size lever gives
access to an adjustment for the set -down position for 12 -in.
records.
Fig. 2-Anti-skating adjustment knob, with its two scalesthe one for conical styli adjusts for as much as five grams,
while the one for elliptical styli adjusts only to three grams,
which is, of course, about as high a force as should ever be used
for these popular styli. The slotted screw head to the left of the
knob adjusts the tonearm cueing height.
Fig. 4-The left -front corner accommodates the speed controls-the lever for the three nominal speeds, and the knob
for vernier adjustment of turntable speed over a range of ±3%.
and the manufacturer claims bearing frictions of less than one hundredth of a gram in the vertical direction, and less than
two -hundredths in the horizontal.
The cartridge mounts on a holder which is locked to the
tonearm head by a single lever. One advantage of this cartridge holder is that the screw head fits into slots in the holder
threads into the plastic often wear with several changesas some of us are wont to make in the search for the best
cartridge for our systems. In the 1218, the vertical tracking
adjustment is built into the head, with a small knob extending
to the right to permit setting for single- or multiple -record
use. This knob turns 90 deg. to either the "S" position for
single-play use, and to the "M" position when several records
Fig.
1-Most adjustments
and the cartridge is held by nuts on the cartridge end of the
screws, so it is not necessary to choose the exact length of
mounting screw to avoid excessive length which would inhibit
the proper seating of the holder in the head. In some cartridge
mounts, the screw threads directly into the plastic mount, and
again the exact length must be selected to avoid interference
with the placement of the holder into the head. Furthermore,
are stacked on the spindle. This control adjusts for 15 -deg.
tracking for either one record, or for the middle records of a
stack of six.
The arm rest is fitted with a lock which secures the arm to
the post and should normally be released before starting to
play. However, if you should fail to release the lock, you have
60
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
6-The underside of the chassis is where the complexity is-and it is remarkably similar to the top -of-the-line 1219.
Fig. 5-Top view of the unit with the platter removed,
showing the simplicity of this side of the chassis. The idler
wheel, shown at the lower left of the turntable well, retracts
from the stepped and tapered motor shaft when the STOP position.
Fig.
only to wait until the unit goes through its cycle and the operating lever returns to the center position. No harm will occur.
You simply release the lock and start again.
The right front corner of the chassis is where the action isthe lever to the right controls the point at which the arm sets
down-for 7-, 10-, or 12 -inch records. The other lever has a
rest position at the center, and start and stop positions. To
initiate playing, you press the lever to the left, and the mechanism takes over: starting the motor, raising the arm from the
rest and positioning it over the lead-in groove of which record
size you have selected, lowering the arm gently to the record,
and returning the lever to the center position. If you prefer,
you simply lift the arm from the rest and position it over the
record anywhere you like-the motor starts and you can either
place the stylus on the record by hand or you may use the
cue-control lever to lower the arm automatically. You can
interrupt the play at any time by moving the cue lever forward-the arm will lift up, but the motor continues running,
and you can continue playing from the same place by moving
the cue lever back.
If you are playing a stack of records, you operate the start
lever and let the mechanism take over-the entire stack will
be played through the unit will stop, returning the arm to the
rest and shutting off the motor. To reject a record and change
to the next one on the spindle, you move the lever to the start
position. You can even play one record continuously by using
the automatic spindle and placing the 45 -rpm adapter disc
on the spindle platform.
over at the other corner of the chassis are the speed controls-a lever to select the nominal speed of either 331/2, 45,
or 78 rpm-and a knob which varies the speed up or down by
three per cent as desired to match the pitch to an instrument,
for example.
the features needed for controlling its action, and appears to
be well constructed. It is, of course, the most recent of a long
line of changers and record players which have been improved
continuously since the introduction of the first Dual in 1927,
when the name came from a combination of both spring drive
and an electric motor in the same turntable.
The platter is die cast of non-ferrous material and weighs
four pounds-always a desirable feature to ensure constancy
of speed. The black and chrome appearance of the unit is
attractive, simple, and functional.
We measured its performance characteristics and found a
signal-to-noise figure of 44 dB, using the old NAB method.
With a standard "A" weighting network, this figure increases
to 62 dB-in itself considerably better than the average "hifi" single -play turntable of a decade ago. Wow-the speed variation below 6 Hz-was measured at 0.1 percent-while flutter
was 0.05 percent measured from 5 to 250 Hz. Cycling time was
measured at 13 seconds when operating at 331/2 rpm, 11 seconds
at 45, and 8 seconds at 78. Well do we remember when a
changer that cycled in 25 seconds was considered acceptableas, of course, it was if you compared it to the early models of
the Capehart, for instance.
The synchronous motor showed no speed variation whatever over a voltage range from 85 to 135 volts, but being synchronous, it was susceptible to frequency variations in the
supply. This is of little concern to anyone in this country,
since electric companies must maintain a close tolerance over
frequency to make interconnections between areas possible.
If the unit were to be used in other countries, it would require a change of the motor pulley, since the United States and
Canada are just about the only places where 60 Hz is the
prevailing frequency of power lines. However, this problem
would arise with any synchronously driven equipment, and it
can be cured, fortunately.
For those who long for a fine turntable but who cannot get
up the scratch for the 1219, the 1218 is a logical choice, and
it will certainly give long and satisfactory service for the
C. G. McProud
average user.
Performance
The 1218 is an especially easy turntable to use. The controls are foolproof, and no harm results from changing a control setting during a change cycle, for instance, or for forgetting
to release the arm lock before starting the playing. It has all
AUDIO
OUR 25th YEAR
JANUARY 1972
Check No. 61 on Reader Service Card
61
www.americanradiohistory.com
Acoustic Research
AR -6 Loudspeaker
System
MANUFACTURER'S SPECIFICATIONS
Speakers: Two; 8 -in. woofer, with 56 Hz resonance in system,
and 1'/2 -in. diameter cone tweeter. Enclosure Type: Acoustic
Suspension. Crossover Frequency: 1,500 Hz. Impedance:
8 ohms. Size: 19'/2 in. W. x 2 in. D. x 7 in. H. Weight: 20
lbs. Price: $81.00.
Fig. 1-Front view of the speaker elements, with the grille
removed. Note the relative sizes of the drivers.
1
Acoustic Research's Model AR -6 has deceptively similar
specifications to the AR -4x. Both are two-way systems, having
8 -in. woofers, crossover between
and 2 KHz, and their enclosures have virtually the same volume.
Dimensions of the AR -6 are 191/2 by 12 by 7 in., and thus it is
one of the few bookshelf loudspeakers truly deserving the
name. These proportions, besides being practical, are aesthetically more pleasing as well. It is supplied with instructions
for hanging and fusing, as well as hook eyes and feet pads.
The tweeter uses the magnet structure of the AR-4x but it has
a cone diameter of 1.5 -in. instead of 2.5 in. A 5/8 -in. dome is in
its center with a viscous damped voice coil behind. See Fig. 1.
We compared the AR -6 and the AR -4x speakers with a
variety of program material and the AR -6 quickly established
itself as the superior speaker. This is not to say that the AR -4x
is not any less of a bargain at $63.00, but to our ears, the additional $18.00 that the AR -6 costs is clearly audible.
The greatest improvement is in the performance of the 1.5 in.
tweeter. Better dispersion, coupled with smoother and wider
response, are responsible for the spacious stereo image. Woofer
response is good down to 40 or 50 Hz with very little harmonic
distortion, a hallmark of all AR speakers.
After our listening tests, we went to the more objective
measurement procedure. System input consisted of '/3 octave
pink noise at 1.6 volt. This gave 84 dB S.P.L. at 40 in. on -axis,
high frequency control set at maximum.
Figure 2 shows the system's frequency response. The dotted
line is speaker response minus room interference. The most
notable feature of Fig. 2C, which incidentally is most representative of what a listener will hear, is its unusual smoothness and excellent high frequency power response.
The lack of harmonic distortion, even at levels in excess of
100 dB, was equally gratifying. See Fig. 3.
Impedance stayed close to its rated 8 ohm value, and with
the high frequency control at normal, never went below 6.75
ohms, as shown in Fig. 4. At maximum setting of the high
frequency control, the impedance dipped briefly to 5 ohms
at 8,000 Hz-still quite safe for any decent amplifier, but an
unlikely balance setting for all but a Victorian living room.
Tone burst response, as shown in Fig. 5, reveals excellent
transient response at all test frequencies. Efficiency was what
one would expect from an acoustic suspension loudspeaker,
medium to low. Twenty to 40 watts is sufficient power to drive
this speaker system, depending on one's musical taste.
After listening to the AR-6 on and off during a three-week
period and comparing it with its biggest brother, the AR-3a,
we had no reason to change our initial high opinion of it. We
predict that the AR -6 will supplant the AR -4x on the best seller
list and probably establish itself as the standard for other
loudspeakers in the under -$100.00 class.
Alex Rosner
1
Check No. 62 on Reader Service Card
noa
100
Fig. 2-Frequency response of the AR -6 loudspeaker to '/3 octave pink noise, A, on -axis; B, 45 degrees off axis, and C,
average of five readings. The dotted line compensates for room
interferences.
10
5
4
=
02.5
1.75
1.0
100 dB
.75
Fig.
90 dB
3-Harmonic distortion
.00
Fig.
at 90 and 100 dB S.P.L.
10,3
4-Impedance curves at two settings of the unit's treble
control.
Illlilll
A
i+lllïl
C
Fig. 5-Tone burst response at A, 500 Hz; B, 8000 Hz, and
C, 10,000 Hz.
62
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
TEST RECORD,
with complete
"EQUALIZATION -EVALUATION" KIT- $5.00
,;-.,:
l»structronaitwERwd,b
... balancing
room acoustics, matching frequencies, tonal transformation, instant comparison of
the various octave -bands of sound, and component tone control evaluation to test
their effect on each octave, individually. Although the kit WILL NOT actually do
the equalizing (you'll need an Equalizer for that), it DOES enable you to make a
subjective chart of your own system -room curve, and pin -points any deficiencies.
You can actually chart the RELATIVE FREQUENCY RESPONSE LEVELS of each of
the ten octaves from 20 to 20,480 Hz, using YOUR PRESENT STEREO SYSTEM,
THIS RECORD, AND YOUR OWN EARS. The 1,000 Hz reference tone and 1/3 octave.
bands of "pink noise" can be quickly and easily compared, then adjusted with your
own volume or balance control, to create an octave -by -octave system -room curve for
your own evaluation of each channel. KIT INCLUDES: A. Instructional 12" LP Test
Record, B. "Why's and How's of Equalization" Booklet, C. 10 Cornputone Room Curve Charts, D. Comparison Jumper Cable.
This kit will introduce you to the fascinating world of Equalization
SEND $5.00 CHECK or M.O. to: SOUNDCRAFTSMEN, 1320
E.
Wakeham, Santa Ana, Ca. 92705
presents the new 1972
Audio Frequency Equalizer.
guaranteed to improve any
fine stereo system!
Now, in a few minutes, you can
accurately "tine" the frequency
response of your stereo system and
room environment to a flat ±2 db!
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.
includes walnut cabinet or
rack mount for commercial installations
$299.50
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: =1/4 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 @ 2v. 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
(any 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.
MASTER OUTPUT LEVEL: "Frequency-spectrum -level" controls for 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, (51/2" x 173/4"x 11").
WARRANTY: 2 -year parts and labor.
Check No. 64 on Reader Service Card
www.americanradiohistory.com
Workbench
Heath IM-105 VOM
EICO 955 Capacitor Bridge
64
66
will do the job just as well. VTVM's have a higher input
impedance and are usually more sensitive, but for general use
around the workshop or for servicing the IM -105 takes some
beating. Input resistance is 5000 ohms per volt on the a.c. ranges
and 20,000 0/V for d.c.-thus the loading effect is negligible for
most applications. For instance, the resistance of the instrument is no less than 5 megohms for the 250 volt range, which
compares quite favorably with many VTVM's.
Circuit Details
Figure shows the basic configuration of the d.c. measuring
circuit. RT1 is a thermistor which compensates for meter resistance changes caused by temperature variations. It has a
negative temperature coefficient and the meter has a positive
one, so the net result is a high degree of accuracy maintained
over a wide temperature range. The two rectifiers connected
across the meter are to protect it from overloads. The movement has a full scale deflection of 50 microamps and the taut band method of suspension is used. The current measuring
circuit is fairly conventional and Fig. 2 shows the potentiometer
arrangement for resistance measurements. Note that a 15 volt
battery is used for the highest range (R X 10K).
1
Heath IM -105 VOM
MANUFACTURER'S SPECIFICATIONS
D. c. Volts: 0 - 0.25, 2.5, 10, 50, 250, 500. D.c. µA: 0- 50.
D.c. mA: 0 - 1.0, 10, 100, 500. D.c. Amps: 0 - 10. A.c.
Volts: 0 - 2.5, 10, 50, 250, 500. High Voltage: 0 - 1000 and
0 - 5000. Accuracy: ± 3% d.c. volts, d.c. amps, d.c. milli amps; ± 2% d.c. microamps; ± 4% a.c. volts, all full scale
deflection. DB: Five ranges, -10 to +56. Price: $47.95.
Vacuum -tube voltmeters (VTVM's) are extremely useful-no
doubt about it-but there are times when a simple, rugged
battery operated multimeter, or VOM like the Heath IM -105,
How It Went Together
Figures 3, 4, and 5 show stages in the assembly which mainly
involved mounting the switch on two printed boards with the
rest of the components. As always with Heath manuals, the
instructions were well thought out and easy to follow. The
boards were clearly marked and the whole thing went together
in less than four hours. I believe it could be done much more
quickly, but, well, I didn't hurry. The calibration instructions
were divided into two sections, one using the power line
voltage, an ordinary 1.5 V cell, and a 1.35K resistor (supplied);
the other employing precision standards. I used a variable
voltage supply with two standard 1% lab meters, but I did check
with the basic Heath procedure. The low voltage ranges were
pretty accurate but the high voltages ranges were out by 5% as
my line voltage was lower than I expected. (All those air conditioners!) However, the instruction book does point out
19.50
R21
R22
80 MS2
10 M12
R23
R25
R24
5 MS2 4 MS2
R26
800kí2150
kíl
R27
45 kS2
RT1
ADJUSTED FOR
R
A METER
50V
10V
250V
500
V0,
RANGE SWITCH
O
O
5
kV
DC
Fig.
1
02.5V
I
p .25V
CIRCUIT
ADJUSTED FO
A METER
CIRCUIT
RESISTANCE
1.5V
RESISTANCE
X10
X100 211.7
15 V
OF5ki2
I
100k12
OF5ke.
kV
DC
1-Basic d.c. voltage measuring circuit.
RANGE
-COM
SWITCH
-COM
Fig.
0
16.68
k9
2-Basic resistor measuring circuit.
64
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
that the line calibration can be used as a temporary expedient
and the controls readjusted when you have access to a known
voltage.
Measurements
The chart shows how the IM -105 compared with the lab
standard and it will be seen that it was well within specifications on all ranges. That is, on all the ranges tested, as I do not
have an accurate high voltage standard, I did not check the
1000 and 5000 volt ranges. The frequency response of the low
a.c. ranges was within
dB from 7 Hz to 100 Hz -which includes all the dB scales likely to be used for audio measurements. Accuracy of the resistance ranges is quoted as being
"within 3 degrees of arc," but even greater accuracy can be
obtained by using precision resistors for comparison; in fact,
calibration,. instructions are given for use with the I.35K
resistor supplied. I found the 41/2 -in. scale easy to read with a
minim tim of parallax error, and I was pleased to see the inclusion of a polarity reversing switch. Both positive and
negative voltages are used by so many transistor amplifiers
these days that such conveniences are very much worthwhile.
I also liked the low voltage (0.25 V, FSD) calibration of the
0.05 mA range -invaluable for measuring those low emitter
or base voltages. All in all, the Heath IM -105 is a first-class,
versatile instrument capable of a high degree of accuracy and,
T.A.
like all Heath products, excellent value for money.
1
Bold Face listing is input;
Light Face is IM -105 reading.
Scale
Fig. 3 -Showing front view of boards with switch.
Max. Error
%, F.S.D.
A.C.V.
2.0
2.0
2.5
2.52
1.2
8.0
19.8
27.9
40.0
150.0
200.0
100
90
100.0
98.1
200
193
10.0
10.1
50.0
50.1
250.0
1.5
20.0
1.5
1.5
6.0
6.0
30.0
0.5
0.47
50
2.0
1.9
10.0
250
0.5
1.0
0.47
0.98
2.0
4.0
1.85
3.95
50
10.0
250
9.0
50.0
2.5
10
45.0
8.0
40.0
149.5 201
252
300
293
400
500
404
506
1.0
1.5
2.0
0.99
2.0
4.0
1.5
6.0
3.95
6.0
30.0
9.5
50.0
20.0
19.9
100.0
8.0
40.0
29.9
40.0
2.5
2.51
10.0
10.1
50.0
50.1
250.0
47.0
98.0
150.0
203.0 255.0
100
200
300
400
94.0
196.0 302.0 405.0
-
-
-
-
0.2
0.4
0.6
0.8
0.18
0.38
0.59
0.8
4.0
6.0
3.95
100
2.0
1.8
20.0
8.0
8.1
80.0
59.0
82.0
102.2
500
17.5
100
40.0
39.1
200
5.9
60.0
1.0
10.0
10.1
100.0
300
400
500
99
205
309
412
515
500
2.5
2.0
2.0
Fig. 4 -Showing side view.
D.C.V.
2.5
10
500
mA
0.05
(0.25V.)
1.0
10
8.0
150.0 200.0
500
OUR 25th YEAR
1.0
1.0
2.0
2.0
510.0
0.05
0
0 05
1.0
2
Check No. 65 on Reader Service Card
AUDIO
1.2
2.0
2.5
3.0
Fig. 5 -Rear view.
JANUARY 1972
www.americanradiohistory.com
positive indication of open circuit conditions! Capacity range
is from 0.1 to 50 µF using a Wien bridge and the open
circuit test will go down to 15 pF or less. A novel shunt
balancing circuit enables capacitors to be measured with a
parallel resistance dowri to about 35 ohms. How does it
work? Let's take a look at the basic circuit as shown in
Fig. 1. VI and V2 form an indicator circuit and any voltage
at C7 will cause the fluorescent bars on the V2 tube to close
accordingly. A 6.3 a.c. voltage is applied to the control R9
which forms a Wien bridge with R6, R10, R11, and C3.
Figure 2 shows the circuit redrawn in the more familiar
bridge arrangement. To simplify matters, the indicating
circuit (V1 and the V2 tube) is shown as a block diagram. The
potentiometer R 10 is in parallel with the standard capacitor
C3 for measuring capacitors having low values of RC-shunting resistance or equivalent resistance. For high values, the
switch S2a, b changes the circuit to put C3 in series with
another control as shown in Fig. 3.
Open Test Circuit
The open test circuit is shown in Fig. 4, and it has some unusual features. The section shown in heavy lines is a Hartley
oscillator and when it is oscillating, the grid of V 1 is negative
and the anode current is small. This means that the V2 indicator tube bars stay open. But what happens when there is
no oscillation? The grid of V then becomes the same potential as the cathode, the anode current increases considerably
and so the indicator bars close. Now, oscillation depends on
the impedance connected across the test leads, and here is
where the designer shows ingenuity. The test leads plus L2,
R12, and C4 form a quarter -wave line at the oscillator frequency (about 22 Mc). So when this line is open at the test
lead end, it represents a short at the input and part of the coil
L1 will appear shorted. This will kill the oscillation in the
Hartley circuit and keep the tube indicator bars closed. An
impedance connected across the test lead input will maintain
the oscillations and cause the indicator bars to open. Simple?
1
EICO 955 Capacitor Bridge
MANUFACTURER'S SPECIFICATIONS
Range: 0.1 to 50 /IF at ±10% accuracy. Short Test: As
ohm, 60 Hz test frequency. Reliable up to 2000
low as
µF. Open Test: As small as 15 pF. Shunt Resistance:
As low as 35 ohms for capacitors above 100 pF. Controls:
Short, capacity, open, RC balance, with on-off switch. Indicator dial range switch. Indicator Tube: Electron -ray with
bright bar pattern. Size: 8Y2 by 5 by 6 inches. Price:
1
$29.95 (kit).
The EICO 955 is a capacitor tester which can measure
capacitors in or out of circuit. Not only that, it can give a
Fig.
1-Capacity measurement circuit.
Short Circuit Test
The parameters of the amplifying tube
V1 are now arranged
that a short across the test leads will close the indicator tube
Fig.
2-Figure
66
1
redrawn to show the bridge.
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
bars and an impedance of between
the bars partially open.
1
and
10
ohms will keep
How It Went Together
No printed boards are used and the components are mounted
direct to the chassis or to tag boards and wired in the oldfashioned way. Quite straightforward and the instructions are
easy enough to follow. Figure 5 shows most of the parts in
position and Fig. 6 shows it fully wired. Total time is approximately four hours.
(and inexpensive) instrument for the engineer or the experimenter. The in -circuit test facility may save a lot of unnecessary
work and bad language. Removing a capacitor from an almost inaccessible printed board is bad enough, but to find it
was OK anyway is frustrating to say the least!
T.A.
Check No. 67 on Reader Service Card
Performance
Accuracy is claimed to be ± 10% at any point on the dial
for in -circuit or out -of-circuit measurement. This is more than
adequate for the usual purposes and even closer accuracy
can be obtained by using precision standards for comparison.
Basic accuracy is not affected by shunt resistance but low
values tend to spread the null point on the indicator. Poor
power factors can cause inaccurate readings for electrolytic
capacitors, but tolerances are usually wide anyway. The open
circuit test gave a clear indication for capacitors as low as
10 pF and the short test worked beautifully. The dial is a fourinch lucite disc, and it is easy to read. Summing up: A useful
Fig.
Fig.
5-Showing parts mounted ready for wiring.
3-Bridge connected for high capacitor values.
V2
R3
R2
R8
L1
R12
JI
V
L2
C4
330
VAC
Fig.
4-Open test circuit.
AUDIO
OUR 25th YEAR
Fig.
6-Wiring completed
JANUARY 1972
67
www.americanradiohistory.com
Classical
GRecord
9eiemrs
Edward Tatnall Canby
users of four-channel matrix equipment will find a great deal of it
coming through those back channels.
Modern and Semi -Modern
Bartók: Sonata for Solo Violin (1944),
Second Sonata for Violin and Piano
(1922). Gabriel Banat, with Lawrence
Smith, piano. Cutty Wren CWR 102,
stereo, $ 5.98.
Two major violin works by the great
Hungarian, with and without piano,
both big pieces, mature, potently
expressive. And a youngish fiddler who
was a protégé of Bartók himself as a
child, and comes from the same geographic region. There should be splendid listening. There is, at the least, very
good listening.
Gabriel Banat is obviously at home
in Bartòk's idiom. He has a sweet tone,
a bit on the gentle side, and his feeling for pitch, as well as his understanding of its supreme importance in
this music, is beyond reproach. No
violinist without this basic musical
gift could hope to make sense of the
difficult Solo Sonata, which he does
with ease.
The only trouble, as I hear it, is
simply a matter of temperament. Mr.
Banat just doesn't have the sheer
gall, the all -potent rhythmic drive,
to project the more furious parts of
these works as they must be projected. The understanding is there.
But the superhuman, daemonic drive
isn't daemonic enough. It's just a bit
too polite in the sound, this performing-but on an immensely high plane,
mind you. Bartók was in truth a daemon when he took to the fiddle.
His writing turns that elegant instrument into a screaming, gutteral,
hoarse monster of straining strings,
so expertly, however, that the instrument reveals whole new aspects of,
shall we say, indecency. A tortured
sound, like the sound of a grossly
overdriven amplifier (where have we
heard that before!) but a sound that is
unforgettable-if the player can rise
to its agony.
Performances:
Others have, and have perhaps
ruined their valuable fiddles or at
least strangled a couple of strings,
'mid buckets of sheer sweat. Somehow,
I sense that Mr. Banat is loth, like
the swimmer who would rather not
get his hair too wet. Perfectly good
swimmer. I find myself urging him
on-more, louder, gutsier!! But he
doesn't. His hair stays dry.
In the slow movements, Mr. Banat
rises to perfection, where beauty of
tone and musical intelligence can have
full sway. He is superb. In the highly
dissonant Sonata for Violin and Piano,
Lawrence Smith, out of Portland,
Oregon, plays an accomplished piano,
if also just a trace on the too -proper
side. The violin -piano recording leaves
the fiddle almost too much in the
background, with the piano taking the
lead. A fine sound but not an ideal
balance (usually it goes the other way,
however, too much violin). The Solo
Sonata sets Gabriel Banat up for
maximum impact, a gorgeous violin
sound, big and full. There's plenty of
"echo" in the resonant recording place;
www.americanradiohistory.com
+
Sound: B+,
B-
Gordon Crosse: Changes. Vyvyan,
Shirley -Quirk, London Symphony
Oröh. and Chorus, Del Mar. Argo
ZRG 656, stereo, $5.95.
A vast modern British oratorio here,
and I hardly know what to make of
it. Curious-it is both modern and, in
many ways, very traditional. In Britain,
the electronic avant garde is, I would
guess, less prominent (though no
less far out) than here, and music
of a modern sort but in the traditional
forms, for the standard "live" instruments and voices, is the thing when it
comes tò being up to date.
This opus is set to a batch of texts
by such as Robert Herrick and William
Blake, but scarcely a word of them is
intelligible in the hubbub, and Argo
does not give. us the printed lines.
It would help immensely, if we could
read and listen 'simultaneously. Anybody who has listened to the big,
modern choral -vocal works will spot
antecedents. and near-relatives galore
for the musical sound. The huge,
clangingly percussive orchestral bursts
remind 'of Carl Orff out of Germany,
with a good taste of Henze too-both
those men skillful in the same sort of
big -stage musical drama that we have
here. But before them, one thinks of
that old pro, Honegger, whose numerous dramatic works, whether cantatas,
oratorios, or what -not, (mostly they
just have names-"Judith," "Nicholas
de Flue," "King David") set the frame
for all of those which have followed.
Honegger, it is more and more clear,
was a real pacemaker, back in the
twenties and thirties. Gordon Crosse
may not even know Honegger's work;
no matter. It is part of his own.
AUDIO
68
B
OUR 25th YEAR
JANUARY 1972
Isn't British music always very much
itself, yet virtually always modeled
on some form of Continental expression? Geographically inevitable. Like
Norman architecture, and British
Gothic. It still happens. In spite of
the Continental influences that come
to mind here-and one can go as far
afield as Prokofiev, with his big dramatic cantatas ("Alexander Nevsky,"
and "Ivan, The Terrible")-Crosse's
"Changes" is immediately British,
even to its inevitable boy choir, the
li'l angels singing as they always do,
high above the vast concourse of
mature performers. And, in its Britishness, the music is most immediately
out of-guess who?-Benjamin Britten,
of course, a larger, less concise idiom
than Britten's, more fluent, more verbose, but borrowing many a nuance,
as who wouldn't? Britten, too, has been
a pacemaker in the field.
A glorious, big performance, enthusiastic and well rehearsed, with the
fabled Vyvyan at her best in the soprano solo and John Shirley-Quirk
the very model of an oratorio basso.
The fi is great too, and all that is lacking is, as I say, the text. Just so we
might know what it was that got such
a whale of a big noise going.
Performance:
A-
Sound:
B
+
Scriabin: The Poem of Ecstasy; Prometheus, the Poem of Fire. Philadelphia Orch., Ormandy. RCA LSC
3214, stereo, $5.98.
I am very suspicious of this sudden
enormous fad for the music of Scriabin,
which this new disc hopefully exploits.
Scriabin and these two works have all
been around for a long time, and until
day before yesterday, nobody was taking
very much notice. Now, whoosh!-Scriabin is in orbit. Especially among the
young, who are the least likely to be
able to understand the immensely complex harmonic idiom of these works
from the early 1900s. Why the sudden
reincarnation?
Oh-so -simple. Not because of the
music, friends, but because of the
ecstasy. The mysterious, exalted OM stuff, the wildly all -embracing, cosmos busting, super galaxy -transcending
karma that this man spouted forth in
words, then turned into music! I don't
think the current fad is musical at all.
It's all about Scriabin the great (selfelevated) mystic. The music itself
leaves me chilled. In fact, the stuff
gives me the horrors; I can't stand its
screaming, introverted, dogmatically
repetitive harmonies, so sickly sweet
they turn sour in minutes, so small AUDIO
OUR 25th YEAR
for complete record & tape
information you need both
Schwann
I
5cr
.
.
arn
The Schwann everybody
knows
frequent revision to keep up with the many new releases in records and 8 -track cartridge and cassette tapes.
The monthly Schwann Record & Tape Guide contains nearly
45,000 listings in classical, recent popular, rock, jazz, folk,
musical shows, etc. Special new listing section lists this
month's releases in all categories.
It takes
Latest Monthly Issue
75C
Schwann II
SEMI-ANNUAL SUPPLEMENT
The Schwann everybody
needs to know
Necessary companion to the monthly Schwann. Contains
pop records more than two years old, classic jazz, older and
re -leased mono classical recordings, classical on lesser known labels, international pop & folk on domestic labels,
spoken, educational, etc., on records and tapes.
Latest Semi -Annual Issue
6oe
Keep Schwann Catalogs at home for reference and to help you decide on additions to your music library. Ask your record dealer for the
latest editions.
SAMPLE OFFER
If your dealer does not have the Schwann publications you
want, we will help you to become acquainted.
SCHWANN SAMPLER consisting of one each, Schwann
(monthly) and Schwann Il (semi-annual Supplement).
SPECIAL PRICE Postpaid $1.25.
Latest monthly Schwann Postpaid $1.00.
13 Latest Semi-annual Schwann II Supplement
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3
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Postpaid 75`
Amount enclosed
$
for items checked above.
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Address
City
State
Dealer's Name & Address
Zip
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137 Newbury Street, Boston, Mass. 02116.
JANUARY 1972
AU
69
www.americanradiohistory.com
GRAPHIC STEREO TONE CONTROL
HAD
THIS TO
HIRSCH-HOUCK LABORATORIES
SAY, "...The Frequency Equalizer performed
fine in listening tests. It was able to tailor
sound very well. The harmonic distortion at
1,000 Hz is virtually nonexistent... IM at 2 volts
was measured at 0.016%,
...
MOLE KV
material, speakers, and individual
preferences.
In other words, it tailors sound to suit your
personal listening reThefements."
program
Graphic Stereo Tone
Control can be used with all
preamp-basic combinations
or receivers with a tape
monitor switch. The system
sells for $99.95 with a 2 year guarantee or $79.95
for an easy -to-assemble kit.
.34,21,11
Frequency response --
0.3dB from 5 to 500,000 Hz
...The output clipping level
occurred at 9.0 volts..."
'HERE'S WHAT WE HAVE TO
SAY, "The Graphic Stereo
Tone Control is Metrotec's
newly developed Frequency
Equalizer. Its flexible 5 segment tone control provides ± 12 dB at 60, 250,
See your dealer or write for name
of dealer nearest you
M ETROTEC
INDUSTRIES
1,000, 3,500, and 10,000 Hz.
This allows precision compensation for room acoustics,
33 Cain Drive
Plainview, New York 11803
Check No. 70 on Reader Service Card
minded (not large minded), that a true
cosmos -inclined genius like Mahler,
who had his own big ideas too, looms
a thousand times larger ..
Any how, RCA has more conventional ideas in its sales department. If
you want to know what their intentions
are, just gander this: " A Sensual
Spectacular! Soaring, surging, shimmering music of naked exaltation!"
And just to be sure, there's a pair of
naked statues embracing on the cover.
Even Scriabin would have been aston.
ished.
Performances: B
Sound:
B
+
1.
1176
k(!¡
has
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Richard Strauss: Don Juan; Till Eulenspiegel's Merry Pranks. Royal
Philharmonic, Henry Lewis. London
Phase 4 SPC 21054, stereo, $5.98.
Rachmaninoff: Piano Concerto No. 2.
Philharmonic,
Ivan Davis; Royal
Henry Lewis. London Phase 4 SPC
21057, stereo, $5.98.
The more I enthuse over Phase 4, the
more London sends us records. I don't
know what's going on in the regular
London line these days; I'm all wrapped
up in this one. The sound is so "different" in these startling discs, not only
in the fi but in the musical qualities of
the mic pickup, that I am reminded of
the original London ffrr impact when
those sensational hi fi 78 rpm shellacs
appeared here some 25 years ago. I
donno what they do over there in Britain.
I only know what my ears say.
Of course, all this would be in vainfor me-if the music itself were not
interesting and interestingly served.
That's the clincher. It is. Whether we are
listening to Stokowski or, as on this
pair of discs, Henry Lewis, Phase 4
fare is intelligently and challengingly
presented in musical terms, and the
somewhat radical recording technique,
somehow, is carried through cooperatively with the music and the musicians
themselves. This is the more remarkable
in that most of Phase 4 is "warhorse"
music, and thus easily subject to casual
performance and a crass hi-fi treatment. It happens often enough! Yes,
I'm aware that makers of a few other
labels will be grieved at my words.
Can't help it.
The two Strauss works have been
recorded so many times that I could
hardly bring myself to try them. Butlovely! Mr. Lewis knows his Strauss
and so do his musicians. These are
warm, natural, outgoing performancesshall I say civilized and friendly-and
for my ears they seem remarkably free
from tiredness or the all -too-common
"it's a job; let's get it over with" atAUDIO
OUR 25th YEAR
JANUARY 1972
titude. Phase 4, taking over this music,
spreads out the inexhaustibly interesting
Strauss orchestrations as I have never
heard them, with uncanny presence.
Whole solo passages I did not know
existed emerge from inside the music.
Phrasings, accompaniments, decorative
figures, even individual musical personalities behind the instruments, are
brought forward. As another company
puts it, You are there.
True, as always, Phase 4 sacrifices
some ensemble blend for this special
close -in look. I would not want to depend entirely on this recording for my
conception of the music's sound. There
are other ways to get it down. But that
does not lessen the impact nor the interest.
As for Rachmaninoff, it is a splendid
performance, no less, though the nature
of the music leads to a quite different
sonic impact. Again, there is a naturalness, a rightness and richness and honesty in the playing, along with perfect
discipline in this superb orchestra. Ivan
Davis, definitely of the young Romantic
generation, is spectacularly good too,
though by temperament very unlike
the granite Rachmaninoff himself. He
is not merely spectacular (though his
technique is up to it) but musical and
sincere. Indeed, the feeling grows that
these musicians really mean what they
say, even if the piece is not the greatest
of masterworks. Believe me, in the last
movement the excitement of performance is palpable, the exchange between
piano and orchestra absolutely electrifying. This is the sort of music -making
you always hoped to get from such as
Toscanini! (But occasionally didn't.)
I was in truth quite stunned, for mostly
Rachmaninoff washes harmlessly past
my ears with little noticeable effect.
Phase 4 in this case is principally
concerned with a massive, well controlled piano sound, since the composer,
like most composer -pianists, never lets
his instrument stop. His orchestra (and
cf. Chopin, Prokofiev, as well) is largely
discreet accompaniment, plus an occasional transitional passage. Even so, the
fi jumps out at you now and then, in
a startling blast of brass or a bass drum
that you can feel, and in the wide dynamic range (on quiet surfaces) which
marks the contrast between loudest and
softest. The solo piano, unlike many
another recorded concerto, is thoroughly blended in with the sound of the
orchestra. Good! (Columbia's Gary
Graffman, for instance, seems to play
in a semi -isolation chamber, apart
from the orchestra.) My only (mild)
reservation is that the deadness of overall
sound, perhaps required for this mic
technique, is not ideal for such music.
Can't have everything.
In that connection, it's worth noting
that via matrixed four -channel equipment there is unusually little differencesignal, or ambient sound, to feed to the
rear channels, in spite of the sharp
stereo separations of the recording. Just
what this indicates in terms of phasing
vectors I am not sure. It could mean a
rather accurate control of mic relationships-or am I just in a mood to toss
praise right and left?
Performances: A-
HEAR HERE
FOR THE UTMOST IN
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Sound: A
RI -PI STEREO
Vladimir Vlasov: Concerto No. 1 for
Cello. Henri Sauguet: Melodie Concertante.
Rostropovich;
Moscow
Radio Orch., Rozhdestvensky, Sauguet. Melodiya/Angel SR 40180,
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stereo, $5.98.
Vladimir Vlasov's big, loud, noisily
Romantic concerto turned my musical
stomach, though the fabulous Rostropovich plays it with impeccable cellistic gusto. It is one of those hard,
business-like pro jobs, written with all
the sincerity of a high-powered Madison Avenue ad campaign and just as
expertly. Great blasts of hideous dissonance to start, proving that we are
modern as all -get -out; then straight
into a comfortable B flat minor, à
la Rachmaninoff. Everything gets in,
even a batch of brassy 1920s nostalgia
(currently popular in Russia), in the
third movement, and plenty of lush
cello melody in the second. But I
found myself longing for somebody
like, say, John Dowland. Or Mozart.
Somebody with modesty and a yen for
briefness.
Henri Sauguet's music is hardly a
model of briefness. His "Melodie"
meanders for an unconscionably long
time and, considering that the composer is conducting (he's 70), it sounds
very old fashioned. At first. But Sauguet has what Vlasov: hasn't: sincerity
and honesty. In the '1960s, Sauguet,
whose heyday was in the naughty
twenties in France, wrote in a half impressionist style which could date
perhaps from 1905. And yet, interestingly, there is an overlay of dissonance
that is both meaningful and, no doubt,
a last reminiscence of flaming youth.
His basic melodic idea, too, is strong,
sinewy, and good for sober development. The longer you listen, the more
modern this music sounds. After
awhile, you'll begin to hear a gentler
Alban Berg, a sweetened Bartók. The
man is not great, but he is real and so
is his music-if you have the patience
to stick out its length.
Performances: A
Sound: B
DOWNTOWN
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71
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Canby's Capsules
CLASSICS REVISITED
Wqrner (trans. Haydn): Three Fugues
for String Quartet. Boccherini: Quartet. in D, Op. 40/3. Sinnhoffer String
Quartet. Orion ORS 7035, stereo,
$
5.98.
Esterhazy
An odd pairing-A Haydn transcription of music by his (Bach -period)
turned
predecessor, and a Quartet by the Haydn -like Boccherini. Easy to hear why H.
C., if
18th
early
for
the
daring
were
harmonies
man's
back to Werner: the older
of
somewhat uncouth, his fugues already sounding "learned" in the later manner
Haydn
graceful
Boccherini's
but
interesting.
figure
minor
Mozart and Beethoven. A
like music makes a pleasing contrast.
Rintzler, New Phil& Orch., Giulini.
36775, stereo, $5.98.
This has much bigger dimensions than the recently reviewed Telefunken recording
(Oct.), larger in the sound, slower, more impressive. With due respect for Giulini
and excellent performers, I don't like it. Too big, too Mendelssohnian for its content,
out of style for the period of this work. The real Beethoven comes through better
via Telefunken.
Purcell: Consort Music for Strings
orchesA good survey of the later Purcell, bordering between "chamber" music and
Beethoven: Mass in C.
Ameling,
Baker, Altmeyer,
harmonia Chor.
Angel
S
and Harpsichord.
Gustav Leonhardt,
Leonhardt Consort. Telefunken SAWT
9506, stereo, $ 5.98.
Bach: Art of the Fugue. Lionel Rogg,
Organ of St. Peter's Cathedral, Geneva.
Angel SB3766, two discs, stereo,
$11.96.
Debussy: La Mer. Ravel: Daphnis et
Chloe Suite No. 2. London Symphony
Orch., Stokowsky. London Ph. 4 SPC
21059, stereo, $5.98.
Historic Organs of England. E. Power
Biggs. Columbia M 30445, stereo,
ODDITIES
Ezra Pound reading his
Translations
of the Confucian Odes. Spoken Arts
SA 1098, mono, $6 50
The Sound of Folk Music-The Original Trapp Family Choir. RCA Camden
CAL 904 (e), sim. stereo, $2.98.
tral. Two sets of recordings intermixed, for small string group and for solo harpsichord, nicely played if with some (Dutch) misapprehensions of tempo. The strings
shape?
again show that peculiar buzzy distortion noted on other Telefunkens. Groove
label?
on
this
why
only
But
mismatch?
stylus
Elliptic
The monumental final Bach opus, unfinished, written merely as a paper abstraction,
date.
here adapts to organ format with immense success-one of the best versions to
lightness,
with
but
massively
plays
he
pitfalls;
all
avoids
organist
Swiss
The young
the unexcellent Bach -period registrations and plenty of color, with a fine grasp of
fugue-I
final
the
completes
brashly
even
He
scale.
large
the
on
architecture
folding
dare you to spot where Bach ends and Rogg begins!
The spectacular Stokowsky Phase 4 series continues-lively, knowledgeable readings
of basic classics, vividly communicative if often inaccurate in detail and occasionally
eccentric, the far-out Phase 4 mic pickup generally revealing of new instrumental
detail, super -impressive in the fi.
Off he goes again-another whirlwind sonic tour of the local organry, out of the
past. After so many brilliant Continental instruments, the modest British items (often
without pedals) seem a bit sedate and colorless and there aren't many available.
(Oliver Cromwell, and the Victorians, did 'em in by the dozen.) As usual, Biggs plays
appropriate local British music, from the 1400s on. He keeps things moving.
Italy) in a feeble
A moving recording, this one. The ancient Pound, now 85, reads (in
or no, he grows
Gravel
Chinese.
-old
-year
2500
of
gravel voice his 1950s translations
clear and
on you as you listen carefully. The famed mind is still there, the words are
superbly
spoken with authority and sense; the command of ideas and of English,
evident. Best heard with text in hand (not provided), but you can get the sense easily
even without.
Picked this up at a rummage sale-it may still be available in some places. The original Trapps were a far cry from the celebrated and banal "Sound of Music." Here
lovely
they are, singing "classical" settings of mostly Germanic tunes, with their
ensemble and perfect taste. From old 78 rpm albums, long before the famed musical
show.
Authentic Music of the American
Indian. Everest 3450/3,
$14.94.
sim. stereo,
Wake Up America, Including the
Battle Hymn of Lt. Calley. "C" Company, with Terry Nelson. Plantation
PLP 15, $4.98.
Exasperating Everest! Not a word as to where or how or when or by whom; but this
source.
is obviously an authentic collection and a valuable reissue, whatever its hidden
for
bass
with
good
clear,
dull
but
sound,
the
by
electrics
rpm
78
are
The recordings
peculiar
the drums. Lots of authentic shoutings and garglings and war whoops in that
Indian fast vibrato, like a bass singer recorded at 33 and played back at a tenor 45!
Generalized notes, no details. Six sides is a lot-so much the better for specialists.
Vietnam;
Nashville -based, mildly peppy patriotism, updated to include Lt. C. and
mixes in
that
backing,
music
country
a
vaguely
to
sings
and
speaks
Nelson
Terry
con. I'd
or
about-pro
and
bothered
hot
old familiar tunes. Not really worth getting
platitudes.
conventional
of
a
batch
it
call
AUDIO
72
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
(Continued from page 34)
would like to have this article regarded as a description
I believe to be a meritorious principle in loudspeaker
design and as a statement of work in progress. My intent
here is not to present a finished design; more work must be
done. I would like to build dividing networks having better
transient and phase characteristics and find better treble
units. (The PM 7 range is up to 22,000 Hz, but the undamped
edges of the whizzer cones produce dissonances at times: JBL
LE -8T units probably would have been more suitable.) Also,
both harmonic and modulation distortion measurements
should be taken, as well as frequency response data, but I
do not have the facilities to do this properly I hope that I
may soon have the opportunity to work on this design with
some interested loudspeaker manufacturer.
I believe that the industry will have to develop measuring
techniques and the appropriate instrumentation which will
provide a valid correlation with listening tests. At present
there is far too much reliance on subjective evaluation.
It is a bit unfair for a reviewer to say of speaker testing, "It
is folly to expect that the average layman could interpret such
a mass of data correctly." This may be true but many engineers cannot interpret data correctly. The data should be
available nontheless, just as it is in the case of amplifiers,
tuners, and phono cartridges. If all loudspeaker data were
presented in terms of measurements taken in an anechoic
chamber with standardized parameters, the intelligent laymen would soon learn how the acoustic properties of such
a chamber differed from those of his listening room and
make the necessary allowances. Also, the day should be long
since past when an equipment reviewer can put the "high
fidelity" label on speaker systems that generate 20% harmonic
distortion at 30 Hz with a one watt input!
I
of what
We simply must have more of the effort exerted by Harwood, Klipsch9, Kaminsky'', Schaumberger", and others to
take the witchcraft out of speaker design and put speaker
evaluation on an objective basis.
LE
As the author says, he is not presenting a finished design, but
experimenters will find the ideas offer an interesting field for investigation. For instance, 8- or 10-in. speakers can be tried
Input to the rear mid -range and treble units can be modified
to change the ratio of direct -to-reflected sound for an optimum
dispersion with a good stereo image. Note that the bass speaker
cones should be quite rigid-especially if a small enclosure is
used The speakers used the G.E.C. `Periphonic" system had
metal cones with a very flexible surround-Ed.
REFERENCES
1.Olson, Acoustical Engineering, Van Nostrand, 1957, pp. 168-9.
2. Holdaway, "Design of Velocity-Feedback Transducer Systems," in
IEEE Transactions on Audio, September -October, 1963, pp. 155-82.
3. De Boer, "Theory of Motional Feedback," in IRE Transactions On
Audio, January-February, 1961, pp. 15-21.
4. Gayford, "The G.E.C. Periphonic push-pull Speaker System," in
Acoustical Techniques and Transducers, 1961, p. 81.
5. Cooke, The Impedance and Phase Angle of Loudspeaker Loads," in
Muirhead Technique, April, 1959, pp. 11-16.
6. McShane, "Hi-Fi Loudspeaker Cones," in Electronics World, February,
1963, pp. 38-40 and 82-3.
7. Novak, "Designing a Ducted -Port Bass -Reflex Enclosure," in Electronics World, January, 1966, pp. 25-8 and 76-7.
8. Phillips, "The Wooden Monster," AUDIO, October, 1965, pp. 48-56.
9. Klipsch, "Modulation Distortion in Loudspeakers," Jour. A.E.S., April,
1969, pp. 194-206.
10. Kaminsky, "The Response of Loudspeakers to Tone Bursts,"Jour.
A.E.S., April, 1965, pp. 119-23.
11.Schaumberger, "Impulse Measurement Techniques," Jour. A.E.S.,
February, 1971, pp. 101-7.
12.Tillett, "Motional Feedback," in HI-Fl Yearbook, 1965/6, p. 73.
sidt
If the reviewers compare
our $19.95 cartridge
with the very best:..
01:11
what can they compare
our $150 Limited Edition
cartridge with?
RMr
tSuggested Retail Price
TM
The incomparable new STEREO -V magnetic cartridges
from Electro-Voice. 8 in all. At the best hi-fi dealers in town.Today.
*"Overall, its "trackability" score was just behind the top -rated cartridges, which are the only
ones we have found to be able to negotiate the difficult passages of this record ("Audio
Obstacle Course") with no more than mild mistracking."- Electronics World, October, 1970
ELECTRO -VOICE, INC., Dept. 124A, 602 Cecil Street, Buchanan, Michigan 49107
In Canada: EV of Canada, Ltd.. 345 Herbert Street, Gananoque, Ontario
In Europe: Electro -Voice, S.A., Lyss.Strasse 55, 2560 Nidau, Switze-land
Check No. 75 on Reader Service Card
www.americanradiohistory.com
5&effrererfere
a
GULTON subsidiary
off) and the delayed sound in the rear
channels (delay on). I should have
mentioned that the stereo output of the
pre -amp is fed into a Y connector and
thence into the single input of the Delta
T. This of course is monophonic, but
you feed this into two of the output
modules, which in turn feed into the
rear channel amplifiers and speakers.
This mono input and double (not stereo)
output is common to most of the delay
devices I have described. Since you are
dealing with non-coherent sound that is
almost totally non -localizable, this
mono rear channel sound is not a problem. The dynamic range of the Delta T
(Continued from page 14)
T. In use, the spare power amplifier
output found on most pre-amps is connected to the input of the Delta T. The
Delta T can be supplied with as many
as five output modules, each of which
is capable of the full 320 ms range of
delay. The delay is simply set with either
or both of two rotary switches, one for
coarse adjustment in 40 ms steps, the
other a fine adjustment in steps of 5
ms. In four -channel stereo simulation,
the coarse switch is rarely used. On each
module is a rocker switch which enables
you to switch between the direct information of the front channels (delay
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is over 60 dB, more than enough to
handle almost any kind of program
material. I found that in my living room,
delays between 10 and 30 ms were the
most effective. In fact, with the Delta T
it was easy to detect the 33 ms limit of
sound fusion in the brain, by simply
switching in an exaggerated delay of 50
or more ms, raising the level of the rear
channels and playing music with plenty
of repetitive transients. The resounding
"slapback" under these conditions was
an eloquent witness for the validity
of the fusion thesis. It was quite
astonishing to select a nice two -channel
stereo recording, run it through the
Delta T with about 20-25 ms delay, and
have the whole room open up with a
spaciousness and heightened sense of
"participation" and reality that was
hard to believe. Switch off the delay
and the effect is dramatic .. the whole
sonic perspective seems intolerably
cramped and circumscribed. Believe
me, it is one helluva effect, but at
$4000.00, this can hardly be described
as home type equipment. The Delta T
is of course a tool for the modern recording studio. For example, take a
group of six string players, mike them
through the Delta T with an appropriate
amount of delay, and all of a sudden the
six violins sound like 12 violins. In the
wild special effects that rock producers
want these days, a highly exaggerated
delay is deliberately used with certain
instruments. The Delta T also has
obvious uses in the public address field.
In closing I should also mention that the
Delta T would be a highly precise and
controllable delay device to replace the
80 inches per second tape delay used in
the Eargle process four -channel tapes.
There would seem to be little doubt
that a good delay unit can add an impressive quotient of realism in the home
listening situation. Now if only someone
can come up with a reasonably priced
.
unit...
.
Early in November, the New York
hi-fi press corps was present at a joint
conference held by RCA Records, JVC,
and Panasonic, which was billed as a
"progress report on the four -channel
discrete disc." It was known that RCA
was investigating the JVC discrete disc,
but the entry of Panasonic into the act
was a surprise. We had the usual
speeches from management and engineering, containing the usual ambiguities. And we had a demonstration of
the discrete disc with a new Hugo
Montenegro recording, which according
to Hugo in person, wí3s especially
arranged and recorded for the fourchannel medium. We also had a clever
example of how discrete the JVC disc
is by the expediency of four people
speaking at the same time ... in German
from one loudspeaker, Italian from
Zip
74
Check No. 66 on Reader Service Card
www.americanradiohistory.com
AUDIO
JANUARY 1972
another, Japanese from the third loudspeaker, and in English from the fourth
unit! Now in the words of
famous
politican
I want to make myself
perfectly clear. The domonstration that
I heard was very impressive. The sound
was very clean, the discrete-ness of the
stereo beyond question ... in all aspects
a rousing success! Alas, there are certain
problems with this concept, which may
not be resolved for some time to come.
The JVC disc has been described in
these pages before. You know that it
works on a sort of modified multiplex
principle, that the carrier requires a
phono cartridge with response to 45-50
kHz, that a demodulater is required.
Now here are some of the statements
that were made at the conference. "The
life of a discrete disc in laboratory testing when played on stereo home
instrument-type equipment already is
equivalent to that of stereo records
played on the same equipment." "Partial mixed -system playback compatibility has been achieved. Discrete
discs, played first in stereo equipment
and then on four-channel equipment,
have a playback life which has greatly
increased within the past four months."
"The playing time for a discrete disc
now equals the playing time of stereo
records at the time of stereo's introduction without sacrifice of the basic signal-
a
.
.
.
to-noise ratio of record systems." I
have underlined the kicker in that last
sentence
which means that playing
time is roughly 20 to 22 minutes. Indeed,
the demo record given to me has
perhaps 23/4 inches of recording on a
side. As to the first statement about
discrete disc life played back on fourchannel equipment, although there are
no statistics available, with present
record playback technology, I'd be
inclined to accept this as fact value.
The mixed system playback is quite
another matter. The crux of things is
quite simply whether the high frequency
carrier will be wiped off the discrete
disc in a comparatively short time. We
were told the life of the disc in this
circumstance had been increased by a
factor of two. But they never gave us
the base figure! In answer to a question
from the floor regarding the life
expectancy of the carrier, it was stated
that the JVC discrete disc would not be
released to the public until the record
could be played on the normal stereo
equipment in the hands of the consumer, without degradation. When
asked how soon this would be forthcoming, the answer was rather vague.
However, it must be noted that JVC
and Panasonic must evidently believe
that introduction of the discrete disc is
not far off, because between them they
...
had six exhibit rooms crammed with
handsome, well -designed working prototypes of all sorts of four -channel
equipment. There were straight demodulators, demodulators with a stereo
amplifier for the rear channels, pre amps with demodulator, integrated
amps with demodulator, four -channel
stereo receivers with the demodulator,
even four -channel compact systems,
and of course the vital phono cartridges.
One by Panasonic is a semi -conductor
piezo-electric type. The JVC cartridge
is magnetic.
As noted, the sound was very good
indeed, the glittering array of equipment most impressive ... the sad part of
the whole thing, apart from the problems reviewed, is that the JVC discrete
disc cannot be broadcast. At least not
in the foreseeable future. The Donen
system would make it possible, but the
FCC would have to do a radical aboutface to embrace this idea. No matter
what the people at the conference poohpoohed about this, the inability to
broadcast the JVC disc is a severe
limitation. Perhaps the JVC discrete
disc can stand on its own as a sort of
audiophile special. It certainly has the
best sound and it would be 'kind of a
shame to lose one of the few chances
we'll have to get a discrete four -channel
stereo disc.
Æ
Heavy Power. 700 Watts.
(High fidelity. The concept isn't new
High fidelity means low distortion.
A good amp will give you low distortion when it's not clipping.
But your typical 150 watt per channel number is going to clip. Even
with the best and most modern
speaker systems, there's just not
enough power to avoid overload
during low frequency passages.
And on musical peaks. You need
heavy power to prevent clipping,
overload and distortion. Phase
Linear is heavy power. 700 watts.
It's the untypical solid state amplifier with the three year guarantee on parts and labor. 700 watts
of high fidelity power at $779 suggested retail price.
- but the power you need to hear it is.)
-
-
POWER
-
Better than 350 watts/
channel R.M.S., both channels driven into 8 ohms, 0 to 20 kHz.
HARMONIC or I.M. DISTORTION
less than .25%; typically .01%.
-
POWER at CUPPING
450 watts
per channel R.M.S. at 8 ohms. 720
watts per channel. R.M.S. at 4 ohms.
270 watts per channel R.M.S. at 16
ohms.
FREQUENCY RESPONSE
to .25
mHz.
DAMPING RATIO
20 Hz.
-
-0
- 1,000
to 1, I,
HUM & NOISE
Better than 100 dB
below 350 watts; typically 110 dB.
-
-
That's not typical either.
The Phase Linear power sound is at your dealer's. Or write 405 Howell
Way, Edmonds, Wa. 98020 for information.
Check No. 74 on Reader Service Card
www.americanradiohistory.com
Weingarten Looks At
Sherwood L. Weingarten
I
Multi -Disc Albums
AH, THE MERCHANTS
Of America,
how well they play the game.
Market something, anything,
with a zinger of an ad campaign, promotion galore, and watch it soar, watch
the cash registers ring. And keep watching until the sales begin to slow. Then
change it a bit, maybe even improve it
a little, and start all over again.
In the record industry, it started with
the dust-catching, scratchy-sounding,
highly -breakable 78 rpm disc. A long
time later entered the 45, singles with
better everything. Then, viola, came the
LP, replete with the usual dozen cuts
(at least nine of which the listener
couldn't care less about). Extendedplay offerings, the EPs, were next,
comparatively short-lived because of
too-high pricing and too-little quality.
Then it was quiet for a while, but only
until tapes began making rather deep
inroads into disc sales; voila, voila,
the double and triple LP packages
started helping the inflationary spiral
climb skyward.
When the WOODSTOCK triple header busted chart records, apparently,
manufacturers took a hard look and
decided the multiple packaging concept
was here to stay-even if there wasn't
enough quality to fill two or three
records, and even if a single performer
or group couldn't hold an audience
that long. And when JESUS CHRIST
SUPERSTAR shook the industry with
its double-album sales, any doubts
disappeared.
The deluge began-and the manure
that was piled thick and high onto pop
recordings was difficult to believe,
virtually impossible to listen to.
Now, not so long after the initial
outpouring, the garbage continues to be
produced. But the meaningful material,
the better quality stuff, is beginning
to surface-far enough, at least, so it
can be differentiated from the rest.
Three recent examples of superb
wheatseeds among the acres of chaff are
FIDDLER ON THE ROOF (United
Artists, UAS 10900), THE 5TH DIMENSION LIVE (Bell, 9000), and Joan Baez'
(Vanguard, VSDBLESSED ARE
6570/1). Each two -disc set is a masterpiece in its own way, in its own genre.
The first, an original movie soundtrack
recording, improves on the long -run
...
Broadway smash by utilizing the talents
of concert violinist Isaac Stern, both
as the mythical title fiddler and as a
tour de force soloist in front of the
studio orchestra conducted by John
Williams.
And for those who were afraid that
Topel, the Isreali star who assumes
the lead role of Tevye, could not compete with Zero Mostel's live performance, it should be noted that the
fears are groundless. The richness, the
warmth, the humor-all are provided,
sung and spoken to perfection.
And Molly Picon buffs certainly will
not be surprised that she too captures
exquisitely the flavor of the ethnic
musical.
There's little need to repeat what it's
all about, what with some 30 million
persons having seen and heard the show
in 25 countries since the original Broadway version opened in September, 1964.
But just in case a reader or two was not
among that mass of humanity, the story
line-based on tales by Sholom Aleichem
-deals with Tevye, his five daughters,
and their life in Russia before the
Revolution. The Jewish family's trials,
and the community's plight, form the
basis of the drama, the laughter, and
the sentimentality that endeared the
show to people of all walks of life,
all faiths.
Highlights of the recording are difficult to select, for it flows not unlike a
lazy but bubbling river, one segment
into the next. The hits, of course, are
"Tradition," "Matchmaker," "If I Were
a Rich Man," "Sabbath Prayer," "To
Life (L'Chaim)," "Sunrise, Sunset,"
and "Anatevka." But there are many
more, not the least of which is the
sterling, sparkling rendition of the title
tune by Stern.
The 5th Dimension package, as
different from the soundtrack as anything could be, includes three verbal
introductions and 11 musical cuts, and
of the latter three are medleys of the
quintet's past chartbusters. It easily
could be considered a "best of" album,
for all the soul-pop winners are there.
The "Love Medley," for example,
features Bacharach-David's "What the
LennonNow,"
Needs
World
McCartney's "All You Need Is Love,"
and Jimmy Webb's "Have You Tried
76
Love?" And the "Laura Nyro Medley"
showcases the singer -songwriter's golden
oldies recorded by the group, "Stoney
End," "Stoned Soul Picnic," "Sweet
Blindness," "Wedding Bell Blues," and
"Save the Country." Webb comes in for
a tribute of his own when the three male, two-female ensemble gives out
with "Up, Up, and Away," the one that
got them up and started in the big time;
"Paper Cup," "This is Your Life,"
"The Girl's Song," "The Worst That
Could Happen," and "MacArthur
Park."
If, however, you prefer single songs,
try "Never My Love," the current hit
that spotlights a solo by Marilyn
McCoo, or Bobbie Gentry's "Ode to
Billy Joe," a 7:45 entry that has each
member of the group assuming a
character in the once downbeat ballad
now turned into a novel success.
Other highlights include Miss Nyro's
"Eli's Coming," with a vocal solo
by Ron Townson; Sly Sylvester's "I
Want to Take You Higher," another
chartbuster, and the big-big-biggie,
"Aquarius/Let The Sunshine In."
Not incidentally, the audience appaluse rarely intrudes on the zesty
musical extravaganza.
As a post script of sorts, if you desire
a one -LP package by the same group,
pick up the new 11 -tune release,
REFLECTIONS (Bell, 6065). Included
are "Let It Be Me," "Sunshine of Your
Love," "Poor Side of Town," "Ticket
to Ride," "Blowin' Away," "Workin' on
a Groovy Thing," "Carpet Man," and
"Those Were the Days." Kind of a
junior -sized "best -of' all by itself,
released, oddly, at the same time as the
double.
The Joan Baez package, oriented for
thèse who appreciate humanity, religious notions, and the working class,
provides 20 tunes (nine of which the
folksinger wrote herself)-plus two on a
7 -in., 33 rpm disc that's included in the
album.
The thrush's voice continues to be
angelic, her pathos -filled appeals to
man's better side never ending. The
dust jacket of the small disc, for
instance, contains a dedication "to the
farm workers of the world, may they
soon cease to be victims."
Best items on the LP, which was
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
JANUARY 1972
recorded in Nashville and sticks mostly
to a country -folk flavor (with some
choral backgrounds tossed in now and
then to contrast with Miss Baez' solo
voice and guitar picking), are not the
singer's own works, unfortunately. The
Baez compositions, in fact, are often too
personal and can make a listener slightly
uncomfortable, almost as if he's become
a peeping tom, one that looks too deep
and touches nerve endings.
One "must melody" is "Heaven Help
Us All," a hit single and huge concert
favorite for the protest -singer. Crammed
with a love for life and a pop -gospel
aura, its lyrics perhaps sum up Miss
Baez' compassion:
`Heaven help the child who never had
a home,
`Heaven help the girl who walks the
street alone,
"Heaven help the roses if the bombs
begin to fall,
"Heaven help us all .. .
`Heaven help the boy who can't reach
twenty-one,
"Heaven help the man who gave that
boy a gun,
`Heaven help the man who kicks the
man who has to crawl,
"Heaven help us all
"
Interestingly, she alters a line or two
(apparently for more impact) from the
text printed inside the dust jacket, something she does occasionally on other
tracks. A liner note explains it this way:
"The differences between the words on
the record and the words in the text are
either intentional or otherwise."
Other songs the listener should not
miss are Kris Kristofferson's "Help Me
Make It Through the Night," LennonMcCartney's "Let It Be," Mick JaggerKeith Richards' "The Salt of the Earth,"
the bluesy "Lincoln Freed Me Today
(The Slave)," "Put Your Hand in the
Hand," and her latest hit single, "The
Night They Drove Old Dixie Down."
The small disc also shouldn't be
overlooked, with "Maria Dolores"
(sung in Spanish) and Woody Guthrie's
"Plane Wreck at Los Gatos (Deportee)."
Of her own works, most poignant are
"Gabriel and Me," a lullaby she wrote
to sing to her son; "Fifteen Months,"
an autobiographical lament about the
time spent waiting for her husband,
David Harris, while he served time in
prison for protesting the draft; "Last,
Lonely, and Wretched," the title tune.
All together, it's something to make
you think-and something to sweeten
your life, if your conscience is clear.
...
*
*
directly to Blacks, has an exceptional
nine -cut disc available, BEAUTIFUL
NEW WORLD (Respect, TAS -2603).
Best tune on the album, distributed by
Stax, is "Don't Cloud Up My Sky,"
a pleasant yet poignant plea for
humanity and the love of it as a whole.
But the most touching piece is "The
Nanny," a narrated ballad about a
woman who plans to take care of her
own grandchildren after years of caring
for others' offspring; if you're in the
Ask a cynic...
if you want the facts
about speaker
quality!
Scratch below the surface of an audio dealer and you'll find a cynical,
opinionated, always skeptical expert. He's got to be ... his continued existence
depends on his ability to pick and choose. When he coordinates a receiver,
a record player and a couple of speaker systems, he is practicing the art
and science of his craft in an attempt to produce great sound
at competitive prices in a trouble -free music system.
The Creative Dealer conjures up systems with a mix of brands often
marrying a top receiver and record player with a speaker bearing his own name.
This is partly pride, but also a striving for the best sound value and so
he works with top designers and manufacturers in creating his signature system.
Maximus is the acknowledged master in this field and has come up
with all the great "Private Label", signature systems. The signature designs
carry the dealers name, but all the great ones show the Maximus Hallmark
either printed label or evident by the sound alone.
MAXIMUS SOUND CORP. 809 Stewart Avenue, Garden City, N. Y. 11530
MAXIMUS WEST 1900 West 135th Street, Gardena, Calif. 90249
-
-
MAXIMUS
All MaximusrM and Maximus made systems are
warranted by Maximus and may be recognized by
their superior sound qualities and (it pride
permits on signature models) our Hallmark.
*
John KaSandra, who specializes in
soft soul with meaning for all races
despite the fact he musically talks
AUDIO
right mood, it can draw tears.
Other tracks that are outstanding
are "Love Is Not The Answer," the
theme of which is that each person has
the right to his opinions and beliefs
as long as he couples them with respect
for the ideas of others, and "Wings On
Our Minds," almost a KaSandra sermon
to Blacks indicating that now that the
physical shackles have been removed
progress depends on a positive mental
attitude.
/E
OUR 25th YEAR
You probably think it's impossible to get the
big sound of a 12 -inch woofer and a mid -range tweeter from an enclosure
measuring only 71/4x101/2x51/2 inches... that is, until you hear the mini -MAXIMUS!
Check No. 77 on Reader Service Card
JANUARY 1972
77
www.americanradiohistory.com
Martha Sanders Gilmore
Leroy Carr: Blues Before Sunrise
Musicians: Leroy Carr, piano and
vocals; Scrapper Blackwell, guitar,
and Josh White, guitar.
Songs: Midnignt Hour Blues, Mean
Mistreater Mama, Hurry Down Sunshine, Corn Likker Blues, Shady Lane
Blues, Blues Before Sunrise, Take A
Walk Around the Corner, and nine
more.
Columbia
C
30496, $4.98.
As Columbia Records states on the
album, this reissue is a "collector's
item" indeed, culled from old Vocalion
acetates. The 16 sides are a kind of
autobiographical summation and sketch
of smilin' Leroy Carr's very brief and
tragic life. Only one month after his
thirtieth birthday, Carr died of drink
following one of his usual all night
parties.
There is nothing but the blues here,
stanza after stanza of references to
Carr's own stomping ground comprised
of barrelhousing women, infidelity,
corn likker, and the inevitable hangovers
symptomatic thereof.
Carr came out of Nashville, Tennessee, singing and playing through his
30 hard years-1905-1935-in such cities
as Indianapolis, where he was influenced by the barrelhouse pianists
of the Black West Side, and in joints
from New York to Louisville.
The party pianist draws his colorful
experiences with bold, basic, blues
lines, sounding older than his years. At
his side is guitarist Scrapper 'Blackwell
whose contribution to Carr's realm
of musical sound is indispensable.
Blackwell, on his portable version of
strings, heightens Carr's barrelhouse
piano with a boogie bent, underscoring
the piano's fuller resonance with a
bull's eye, finger-pickin'-good approach,
replete with flatted fifths. The honkytonk guitar work of Scrapper Blackwell
is a joy to hear and cannot be overestimated. The team appear as well
suited as Siamese twins!
We are treated to young Josh White
on three tracts in which the total effect
has the dimensions of an entire band.
White can be heard on "Big Four
Blues," "Shining Pistol," and "It's Too
Short," the latter taken at a fast pace
and is not without humour.
These blues stem from the two-year
period from 1932-1934 and are sincere,
salted -in -the-shell comments on Carr's
sordid, unwholesome existence bouncing around from joint to joint, under
the influence (one suspects) and under
the aegis of his own personal art of
urban blues.
These were the days of the railroads
and we hear the train whistle quite
distinctly in "Big Four Blues" in which
the clang, clang of the train is duplicated
by the two guitars to a boogie beat. Carr
is lilting and rocks to and fro in "Southbound Blues," singing "I mean I'm
gonna ride that Dixie Flyer" to the tune
on Blackwell's twangey guitar. Blackwell
has a keen ear for the nuances of
punctuation, pockmarking and clarifying Carr's keyboard statements by
executing deft and deliberate notations
on an instrument that differs in timbre
and temperament from the piano.
One gets the feeling that Carr's
piano is secondary to his voice and is
used to further elaborate his feelings
and inclination to tell it like it is. His
piano style incorporates the suspended
notes and rolls of the old silent -movie
house pianos but his sound does not
come through clearly here, frequently
lurking behind the curtain. However,
the higher, more penetrating notes of
the guitar have no trouble breaking the
sound barrier and listeners may be
grateful for their rather pointilistic
insistency.
Some of the outstanding cuts, many
of them familiar, are "Midnight Hour
78
Blues," a seguing "Hurry Down Sunshine" which is fairly well developed
and wherein Carr cuts some fine jazz
licks: "Blues Before Sunrise," a melodic,
lyrical tune reminiscent of the work of
Robert Pete Williams, and the circularly
rhythmic "Take A Walk Around the
Corner," full of guns and pistols and
achieving a corral of sound which
encircles the integrated effort. A masterpiece!
This music deserves close attention
and, as background music, fails in that
it might sound repetitious. But, sit thee
down, listen, and you shall discover
infinite variety and charm as in "I
Believe I'll Make A Change," featuring
Blackwell's excellent guitar.
Composer Carr's voice embraces a
wide range and displays a fine technical
facility, particularly in spots where he
successfully seeks those high notes and
has no trouble holding them, drawing
out his words to further emphasize his
phrases.
Columbia has considerately spared us
the dreaded rechanneling for stereo
and its accompanying machinations.
All things considered, it has not only
produced an LP of exceptionally good
sound reproduction but has preserved
the authenticity. The sound is expectably uneven, however, and varies
from cut to cut-some blues were recorded in New York, others in St. Louis.
The piano is not lucidly crisp and
separate but we're glad it wasn't
doctored up.
This is an inimitable collection for
both the blues aficionado and music
lover at large. There is never a dull
moment and Carr's down-home piano
and vocal work is pure, genuine, and
raw. Here is a collector's item and blues
classic. Get this one!
Performance: A
AUDIO
www.americanradiohistory.com
OUR 25th YEAR
Sound: BJANUARY 1972
Classified
FOR SALE
Rates: 25¢ per word per insertion for noncommercial advertisements;
50e per word for commercial advertisements. Frequency discounts
as follows: 2 times, less 15%; 6 times, less 20%; 12 times, less 30%.
Closing date is the FIRST of the second month preceding the date
of issue. Payment must accompany all orders under $10.00. Use the
handy self-addressed, postage paid card at the back of this issue.
When replying to AUDIO box number ads. send letters c/o AUDIO,
134 No. 13th St., Phila., Pa. 19107.
ALTEC, JANSZEN, THORENS, Revox, Tandberg,
Beyer, Citation, Dual, JVC, Pioneer, others at
US PX prices. No catalog, quotes only on immediate domestic delivery. Audiofax Unlimited,
Box 7961, Atlanta, Ga. 30309.
DAYTON WRIGHT, B&W, Radford, IMF, Sinclair,
Phase Linear, Quad, Transcriptors, Decca, Braun,
Ampex, SS1 Turntable. Transcendental Audio,
1214 Walden Ave., Buffalo, N.Y. 14043.
SAVE UP TO 45% ON MAGNETIC CARTRIDGES
Shure, Empire, Pickering, etc. Send cartridge
name, model number and stamped self addressed
envelope for prices to PARTS, P.O. Box 587,
Englewood, N.J. 07631.
STEREO SYSTEMS LOW PRICES! Write or call:
Purchase Radio Co., 747 Main St., Buffalo, N.Y.,
14203 (716) 854-2124.
FOR SALE
FOR SALE
CASSETTES -Unique titles including old time
radio, educational, language. Send 10$ for new
16 -page 1972 catalog covering 8 -track and
cassette blanks plus hard -to -find accessories.
Cassettes Unlimited, P.O. Box 13119A, Pittsburgh,
Pennsylvania 15243.
SONY 777 Taperecorder four track stereo sound
on sound. New York (212) 969-1971,
PROTECT YOUR LPS. Poly Sleeves for jackets
5C Inner sleeves 4$ Poly lined paper sleeves
100 White jackets 25C Postage $ 1.00. House
of Records, Hillburn, N.Y. 10931
AMPEX 602 Transport with Ampex Quarter Track
OPERA TAPES -Great performances of past
35 years. Free catalog. Ed Rosen, P.O. Box 97,
Freeport, N.Y. 11520,
BASF, MEMOREX, SCOTCH reels, cassettes,
8 -tracks. Lowest prices. Satisfaction guaranteed.
S&S Audio, Box 2065, Champaign, II. 61820.
STEREO HI-FI SALE. Nationally advertised
amplifiers, tuners, speakers, tape decks, etc.
Discounting to 40% since 1959. Arkay National,
1028-05 Commonwealth, Boston, Mass. 02215.
AMPEX PR -10-2, 4460 tape recorders, MX -10
mixer, Berlant 30 tape recorder, REK-O-KUT
BRAUN, Germany's finest in speakers, tape
decks, turntables. Catalog and dealer list 25C. ADS,
P.O. Box 293, Huntsville, Ala. 35804.
PROTECT YOUR RECORDS. Cardboard replacement covers, plastic lined sleeves, 78 and 45 heavy
sleeves, hinged record set boxes, 12", 10", 7".
Cabco A-2, 89 East Woodruff, Columbus, Ohio
43201.
DYNAMIC RANGE EXPANSION can restore
inert undulating sensitivities into spectacular
stereophonic realism
The HARMONIC WAVE
FORM PROCESSOR is $119. Postpaid, connects easily, and is completely guaranteed.
Information
free.
AUDIO
ENGINEERING
LABORATORIES, INC., King Ferry, N.Y. 13081.
...
REVOX,
QUAD,
Thorens,
Stanton,
Ortofon,
P.E., Sony, Dual, Marantz, Bozak, S.A.E., Rabco,
KLH, Dynaco, Barzilay Cabinets. Interiors Plus
Sound, 1322 E. Commercial Boulevard, Ft.
Lauderdale, Florida 33308 (305) 771-4715.
INDIVIDUAL HAND
PICKED, guaranteed lab
tested & aligned custom components from Crown,
Infinity, Audio Research Corp., Decca, Frazier,
Quad, JBL PROFESSIONAL, Rabco, Transtatic,
Stax, I.M.F., Revox, Tandberg. Free consultation
and technical assistance with purchase. We save
you SS with FACSIMILE REPRODUCTION at
Music and Sound Ltd., 413 Johnson Street,
Jenkintown, Pa. 19046 (215) 885-4214.
ADVENT 101 DOLBY $85. Demo. Verhoeven,
190 Permanente, Mt. View, Calif. 94040.
QUAD for the closest approach to the original
sound. Audio equipment for the serious music
listener. For details write Audio Imports, 5557
Versaille Drive, Indianapolis, Indiana 46227.
IIP MOOG SYNTHESIZER $3975.00, Scully
V.P. Lathe 53600.00. Must sell because of relocation. John Michaelson, 6540 E. Lafayette,
Scottsdale, Arizona 85251 (602-947-1445).
AUDIO
OUR 25th YEAR
CROWN DC -300, McIntosh C-26 and MR -71,
Rabco SL8E, KLH Model 41, Metrotech Equalizer.
O'Connell, 22 Bremond St., Belleville, N.J. 07109.
Heads As new -$290. KLH 18 FM Tuner -$80.
More, send for list. RDD, 1807 Elmcrest, Arlington,
Texas 76012.
Imperial II disc recorder, Telex 811 8 -track cartridge recorder, Schober Reverbatape, EV 654
microphones. M. E. BUNKER, Box 302, Bellflower, California 90706. (213) 865-0934.
FCC "TESTS -ANSWERS" . . . Original exam
manual for F.C.C. First and Second Class License
-plus-"Self-Study Ability Test."
Proven!
Satisfaction Guaranteed. Command, Box 26348-L,
San Francisco 94126.
JBL PROFESSIONAL; 2-4520 rear loaded horns
with 2 2205 drivers in each. 2-2440 drivers with
2390 lenses. 1-2440 driver with 2305 lense.
4-075 tweeters. 2-N 7000 Xovers. 2-3150 (N500)
Xovers. Would prefer to sell as 2 complete systems.
Also -sine -square generator, 1 Neumann phantom
power supply for 2 mikes & 2 supplies for 5 mikes.,
2 Marantz nine power amplifiers, 1CM CC -1 pre amp., Earth Audio, North Ferrisberg, Vermont.
1
(802) 425-2105.
TANNOY 12" Dual Concentric Monitor speakers,
purchased 1968, pair $ 170, 7002 Horrocks,
Philadelphia, Pa. 19149.
WIRED, SELF -POWERED background music
adaptor to use with your present FM -525.00.
Thieves Warehouse, P.O. Box 8057, Pensacola,
Florida 32505.
SCULLY Professional Tape Recorders, from 1 to
24 tracks, complete recording studio packages
designed to order featuring W.A.L. console systems
and other leading professional audio products.
Wiegand Audio Laboratories, R.D. 3, Middlesburg,
Pa.
17842-(717) 837-1444.
DISC RECORDING EQUIPMENT: Complete
mono, and stereo cutting systems featuring rebuilt Scully, Neumann, Van Eps, and Fairchild
lathes and new W.A.L. amplifiers. Priced from
$2500.00 Wiegand Audio Laboratories, R.D. 3
Middlesburg, Pa. 17842-(717) 837-1444.
OVER 20 YEARS SUCCESSFUL DISCOUNTING
OF AUDIO EQUIPMENT insures best value and
service. Specialize in Stereo Components, Tape
Recorders, Cassettes, Magnetic Cartridges, Sleep
Learn Equipment, etc. LOW QUOTES, FREE
CATALOG, DRESSNER, 1523A, Jericho Turnpike,
New Hyde Park, New York 11040.
INFINITY AND CROWN SYSTEMS -AKG
microphones, UREI limiting, Fairchild equipment,
Rabco, more. Finest reproduction possible. Barclay,
503 Haverford Ave., Narberth, Pa. (215)
MO -7-3048.
FIRST BREAKTHROUGH IN RECORDING TAPE.
Originally made by America's leading tape manufacturer 24.00' mylar, 7" reel, $2.29: 1800' mylar,
7" reel, $1.69: 1200' acetate, 7" reel, $ 79.
Write for quantity prices, AAE, 218 Columbia St.,
Utica, N.Y. 13502.
KLIPSCH, TANNOY, BOZAK, MARANTZ,
THORENS, RABCO. No discounting. Superior
Sound, 1801 Brewerton Rd. (Rt. 11) Syracuse,
N.Y. 13211.
INFINITY,
Audio
Research Corp. amplifiers,
Linear, Quad, Decca. Controlled
multi -directional dispersion; electrostatic, transmission -line Trans-static 1 speakers. Brochures
available, other components. Paul Heath, 81 Big
Tree St., Livonia, N.Y.
SACRAFICE: MARANTZ 7T & 15, Teac Al 200U,
Garrard SL95B & ADC -mounted, huge beautiful
cabinet. Wharfedale W60C's. $1100, including
personal delivery anywhere. Terms. MS, 1028
George, Sharon, Pa. 16146.
SAE,
CROWN 1C150
WORLD'S FINEST SPEAKERS -on demonstration -Audio Research 4'x6' panels, Infinity SS1
pre -amp,
as
new
$
180.00,
DECCA 4RC pickups, new, tested, $48.00 each,
EICO 3200 FM tuner, excellent, $40.00. N. Little,
3370 Satinwood, Santa
WA2-3454.
Maria,
Calif.
(805)
Phase
(improved version), 8 Quad system, B&W 70's,
trans static speakers, inquiries invited. Paul Heath,
81 Big Tree St., Livonia, N.Y. 14487, (716)
BRAINWAVE FEEDBACK. Electroencephalophone
346-5630.
teaches alphawave control. J & J Enterprises,
24120-A 3rd West, Bothell, Wash. 98011.
RECORDING TAPE 2400' reel
IMF STUDIO:
MONITOR MARK 3 speaker
systems; Concord Dolby Cassette decks; Otari
professional tape decks; Auricord cassette tape;
Decca and Goldring cartridges in stock. We take
tradeins and have mint condition equipment for
sale. Audiocraft, South Rockwood, Michigan
48179. Telephone (313) 379-9945.
JANUARY 1972
$ 15.00 dozen,
12.00 dozen, 1200' reel $ 9.00 dozen.
Postpaid
guaranteed.
Mitchell,
Box
444A,
Flushing, N.Y. 11367.
1800' reel
$
CUSTOM HI-FI a $300.00 equip. enclosure for
the custom hi-fi man that will cost less than $ 30.00.
Send only $2.00 now for your guaranteed instructions -R. Marano, P.O. Box 197 Brooklyn, N.Y.
11237.
79
www.americanradiohistory.com
FOR SALE
FOR SALE
FOR SALE
BUY DIRECT FROM ENGLAND'S HI-FI MAIL
ORDER SPECIALIST! Save on SME, lak,
Acoustical, Goldring, Decca, Bowers & Wilkins,
Thorens, Tandberg, Revox, Gold Speakers, GarKEF,
rard, FR, Dual, Lowther, Wharfedale,
Celestion, Transcriptors, Radford, etc. Insured
shipping quotes free or send $ 2 bills for catalog ($3
airpost). Goodwin Ltd., 7 Broadway, Wood Green,
London N22, Visitors welcome to showrooms.
AURORA LIGHT PAINTING. Actual 24x30"
painting highlighted with miniature lights that will
flicker, flash, and dart with your music. Connects
to speaker. Hangs on wall. "Christmas" Tree
or Golden Gate Bridge paintings. On black
velvet $109.50. On grained wood $89.50. Free
brochure. Ripley Projects, 245 North Point,
Suite 402, San Francisco, 94133.
SOUND SYSTEM INTERNATIONAL presents a
revolutionary radial track tone arm and turntable.
AUDIO RESEARCH components and speaker
system; also Infinity Systems, Revox, and Thorens.
D S Audio, 410 East Evergreen Road, Lebanon,
Penna. 17042. (717) 273-6314.
8 ohms at below 0.1
percent distortion -the INTEGRAL SYSTEMS
MODEL 250 for $250. Write for details. Integral
Systems Corp., Box 12, Winchester, Mass. 01890.
250 WATTS RMS into
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.
RECORDING
ENTHUSIASTS -IMPROVE
RE-
impedance converters
terminate microphones properly, while allowing
cable extensions to 500 feet without performance
deterioration. Switchbox-handles-to three recorders, for dubbing, editing, and mixing.
WRITE: Aids to Recording, RUSSOUND/FMP,
Dept. 6, P.O. Box 476, Exeter, N.H. 03833.
CORDINGS
Inexpensive
FLORIDA Discount prices on most major brands.
Full service facilities. Stereb Sounds, Inc., 3501
Biscayne Blvd., Miami, Fla. 33137.
1000 WATTS RMS into 8 ohms at below 0.1
percent distortion, electronic power level display.
Switchable for either two or four channels of
amplification-the INTEGRAL SYSTEMS MODEL
1000 for $ 1000. Write for details. Integral Systems
Corporation, Box 12, Winchester, Mass. 01890.
HI FI FURNITURE? See toujay designs at S.E.E.
7O's High Fidelity exhibit. 443 Park Ave. S.,
N.Y.C. 10016, Tues. to Fri. 10-6, Sat. 10-4. Full
line brochure 25C.
OPERA TAPES -Records "live" performances,
broadcasts. Free Catalog, Hathaway, 49 Merbrook
Lane, Merion, Pa. 19066.
DO-IT-YOURSELF. PROFESSIONAL ELECTRONICS PROJECTS -$1.00 up. Catalog 25C. PARKS,
Box 25665E, Seattle, Wash. 98125.
tapes,
...
prerecorded stereo
Stereotone -Tapes, Box 657,
BASF RECORDING TAPE
postpaid.
Sterling, Illinois 61081.
SCOTCH
RECORDING
TAPE CENTER,
TAPE, lowest prices.
Washington, D.C.
Box 4305B,
20012.
THE WORLDS
FINEST SPEAKER AMPLIFIER COMBINATION,
JVC 5011 super preamp, Transcriptor, EPI Tower,
best
Finest,
specialists.
Electrostatic
Quad.
equipped laboratory in the country. Formerly
supplying to professionals only. Now you can
benefit from the unique services of THE AUDIOLAB,
146 French St., New Brunswick, N.J. 08901
B&W 70CA, PHASE LINEAR,
Brochures available. Paul Heath, 81 Big Tree St.,
Livonia, N.Y. 14487 (716) 346-5630.
DISCOUNTS -STEREO COMPONENTS & SYSTEMS. Lowest possible prices on quality brands.
For fastest service, lowest cost -get our quote!
Redwood Stereo Co., P.O. Box 2794, San Rafael,
Calif. 94902. (425) 472-3525.
NATIONALLY advertised Audio Equipment, Cost
Plus 10%. Stereo World, 3250 Duke Street,
Alexandria, Virginia 22314.
BLOWwith
MEDIOCRITY
TRANSCEND
elektrostat Ear Loudspeaker, ERA Transcription
turntable ensembles, HENCOT tape recorders,
ORTHOIONPHASE Sound Source, FANE lonophase
speaker, GE -GO transducer cells and systems,
G.H. HADCOCK unipivot tonearm, AUDIX Stereo
FREE 64 PAGE CATALOG offers hundreds of
recordings or rare renaissance, baroque and
classical music. Some records priced as low as
$1.00 each! All late recordings. In stereo only.
Musical Heritage Society, Box 932 -AU, New York,
N.Y. 1002 3.
STOP AUTO THEFT!! Easily installed electronic
device disables ignition system!! 12 or 6 volt!!
Guaranteed!! Send $6.95-TBOR, Box 1692-A,
F.D.R. Station, New York, 10022.
-2
AMPEX MODIFICATIONS AND REBUILDS
track to 8 track -Conversion Transistor Electronics -Studio Accessories -Mixdown PanelsBKM Associates, Box 22, Wilmington, Mass.
01887.
SHURE V15-11 improved, $47 and old cartridge,
shipped prepaid. STEREO Shop, 1209 1st Ave.
SE, Cedar Rapids, Iowa
52402.
LOW, LOW, PRICES, on Audio Equipment, L.P.
Records, and Tapes. All factory fresh, 1st quality
items. Trained personnel at your disposal for
audio consultation. We accept Master Charge.
Write for FREE CATALOGS to Mr. A, Dept.
AMO at SMG DISTRIBUTORS, INC. 46-35 54th
Road, Maspeth, N.Y. 11378, or call (212)
786-3337.
mint condition. Still under
MR -77 Tuner -C28
factory.
Preamp-Mc2100 Power amp. -M13 Scope.
Over $2000.00 value -only $1495.00. Being
drafted soon. Reply to Box AD1-2.
McINTOSH-All
guarantee
in
from
-
CLAVICHORDS
AND
HARPSICHORDS
New Flemish Harpsichord, curved bentside,
uncompromising classic construction and detail,
$ 295. Other kits from $100. Send for free brochure. Zuckermann Harpsichords Inc., Dept. R,
160 Sixth Avenue, New York 10013.
Free
catalog -Western
DISCOUNTS.
HI-FI
Electronics, 7121 Rich Ave., Newark, Calif. 94560.
1800' NEW MYLAR TAPE IN HINGED BOXES;
12 reels for $15.00 postpaid. Send for other
price lists to WIDE RESPONSE, 2926 Bentley
Ave., Los Angeles, Calif. 90064.
MAGAZINE. The
first issue (January, 1889) is NOT the rarest
edition. Did you know, that the rarest sells for
up to $1,000 dollars! Just published was our
retail -price booklet of all old issues of this magazine
1889-1971. Send $2.00 for your copy to Ostfeld
Publication Research Institute, 29 East Madison
Str., Suite 1301, Chicago, Illinois. 60602.
NATIONAL GEOGRAPHIC
CROWN SX-724; NAB adapters; 7 factory sealed
rolls scotch 203-'/4-3600' tape; $800.00 (203)
(201) 249-9191.
447-2689.
BARCUS-BERRY, piano transducers now available to the recording studio, the professional
musician and the serious student. Make piano
recordings of the finest quality on location, at
home, or in the studio. Acoustics no problem.
These piano sensors are being enthusiastically
accepted by the professional recording studios
and musicians everywhere. This piano pick-up
system is a must for the pro. Write for our product
information bulletin. Cath -Mar Recording Service,
17113 Cambridge, Allen Park, Mich. 48101.
Phone (313) 278-2278.
CROWN CX 822 with two microphone preamps,
portable case, NAB reel adaptors. Purchased new
for $2000.00, as new $1450.00. Reply to Box
AD1-1.
ELECTRO -VOICE MICROPHONES: New, factory
packaged, guaranteed. Must reduce stock. 50%
off. Send for information. P.O. Box 304, Yeadon,
Pa.
19050.
HEAVY DUTY 12" ANTI-STATIC TURNTABLE
MAT, $4.95 postpaid. Creighton Audio labs.
740 Haven PI., Linden, N.J. 07036.
Graphic control unit, JORDANWATTS loudspeaker
module. Also, QUAD, DECCA, RADFORD, B&W,
HARTLEY, and
PHASE LINEAR, HOPKINS,
ADVANCED
SYANTIFIC AUDIO. Information,
ELECTRO ACOUSTICS, 1610 South Park Avenue,
Buffalo, New York 14220.
FREAKS" and discerning people can
now get the amplifier that's "wiping out" all
other amplifiers at test clinics across the country
and is better than test equipment! Kit only $60.
Send for Free Catalog SWTPC, Box 32040B,
San Antonio, Texas 78216.
"HI-FI
SCOTCH MAGNETIC TAPE, discount Box 167A,
Orwigsburg, Pa.
TV & RADIO TUBES 360 EA. Free 48 page
Color Catalog. Cornell 4215 A University, San
Diego, California 92105.
2505 VERSUS MARANTZ 32,
Citation Twelve, and Dynaco Stereo 120. The
winner? Send $1 today for test report, refundable
with $7.50 yearly subscription. THE HI -Fl
NEWSLETTER, Box 593, Hialeah, Fla. 33011.
McINTOSH
_
GET "MUSIC ONLY" FM Programs. SCA Adaptor
fits any FM tuner or receiver. Free list of Stations
with order. Kit $14.50 (with Squelch $ 19.50)
Wired and Tested $25.00 (with Squelch $29.95)
All plus postage & insurance. Thousands Sold.
SWTPC, Box 32040A, San Antonio, Texas 78216.
ARMY GOT ME! Sony TA2000 Preamp, $225.00;
Sony ST5000F Tuner, $285.00; Sony TA32O0F
Amplifier, $250.00. All two months old, spotless.
Fisher Model 202-R AM -FM Tuner, cost $349.50
and matches the finest today, $75.00. Lowrey
TLO-K organ
www.americanradiohistory.com
old,
perfect,
cost
HELP WANTED
to make records for five
companies. We train, equip and provide protected
franchised territories. Modest investment required.
Send resume to Mr. Bloch, 418 N. Main St.,
Englewood, Ohio 45322.
Serious recordists
STEREOS
Automatic Radio, Blaupunkt, Boman Auto
radios -Tape players Dual, Garrard, PE Record
Changers, Sony Superscope, Roberts Norelco,
Craig Tape recorders, Bogen, Grundig, Telefunken,
Shure, Pickering, Grado, Cartridges, Auto and
Home Accessories. Unbeatable prices. Write:
MARTY'S, 2414 University Blvd. West, Wheaton,
Maryland 20902.
COMPLETE LIST OF PRICES
top manufacturers of stereo equipment.
Send $1.00 for catalog, or write for quotations on
all major brands of stereos.
STEREO COMPONENT CENTER
465 High St.,
FOR
AUDIO
80
three months
$2190.00, sell $1595.00. Alois Osti, Greenwich,
N.J. 08323.
Morgantown, West Virginia 26505
Check No. 79 on Reader Service Card
OUR 25th YEAR
JANUARY 1972
SERVICES
RADIO PROGRAMS
RECORDS
ACOUSTECH AMPLIFIER REPAIR. Original
performance or improved specifications. BKM
Associates, Box 22, Wilmington, Mass. 01887.
RADIO RERUNS. Complete broadcasts of old
favorites. Catalog free. Box 724, Redmond, Wash.
SHOW ALBUMS -Rare. Out-of-Print LP's. Free
large list. Broadway/Hollywood Recordings. Dept.
A, Georgetown, Connecticut 06829.
DON'T PAY the high mail order prices. Theives
MOST AMAZING
Warehouse is coming to your area. Franchises
available. Theives Warehouse. P.O. Box 8057,
Pensacola, Florida 32505.
RENT STEREO TAPES $1.50 week. Catalog
250. Tape Library, Box 8126, Washington, D.C.
20024.
CUSTOM STYLUS and cartridge re-tipping,
repairing. (Weathers, Ortofon, Edison, Shure,
etc.)
Box 322A. Tuckahoe,
N.Y.
10707,
914-SP 9-1297.
CUSTOM RECORDING
98052.
SHOW ever produced for
Radio, Ken Nordine, narrator and network cast.
Complete series on 19 Cassettes. Volume 1
ready NOW! Subsequent releases, one per month.
$3.98 each postpaid. Money back guarantee.
"Incredible, But True!", Sawyer, Michigan 49125.
OLD RADIO PROGRAMS at low prices yet
a large selection. Catalog 500 The Best of Radio,
P.O. Box 1692, F.D.R. Sta., New York, N.Y.
10022.
OLD RADIO
programs catalogue 250. Steve
Monaco, 1306 Park Ave., Des Moines, Iowa
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.
OLD RADIO
PROGRAMS.
Catalog
(refundable). The Radio Vault, Box
Wyoming, Michigan 49509.
LEARN Electronic Organ Servicing at home.
All makes including transistors. Experimental
kit -trouble -shooting. Accredited NHSC. Free
Booklet. Niles Bryant School, 3631 Stockton,
Dept. D, Sacramento, Calif. 95820.
OLD RADIO PROGRAMS on Cassettes or Reels
high quality, low prices thousands of your
favorites live again, priced as low as $8.00
for 6 hours, Catalog 500. Remember Radio Inc.
Box 2513 Norman, Okla. 73069.
TRADE STEREO TAPES, $1.25 each postpaid.
Minimum three. Tapetrade, Box 2181, La Jolla,
OLD RADIO SHOWS! Collector wishes to sell
or trade. Joel Bellman, 1012. Lake Forest Dr.,
Claremont, Calif. 91711.
1
Calif. 92037.
50315.
1.00
9032,
$
NOSTALGIC RADIO PROGRAMS on tape.
Six hours only $7.00. Catalogue 250. Nostalgic
Radio, Box 29D, Peoria, III. 61601.
NEW YORK AUDIO SOCIETY offers you a
comprehensive program and numerous benefits.
For details write: N.Y. AUDIO Society, Dept. A,
215 Adams St., Brooklyn, N.Y. 11201.
GOLDEN AGE RADIO -Your best source for
radio tapes. Box 8404-D, Olivette, Missouri 63132.
OLD RADIO PROGRAMS. Reels or cassettes.
Free catalog. Fred Berney, 5931 S.W. 8 Street,
Miami, Fla. 33144.
EQUIPMENT WANTED
MAKE MONEY IN MUSIC, Musician or not!
New book tell's all. Only $3.00, Ruscan Enterprises
305-D Peasley St., Boise, Idaho 83705. Money -
CASH FOR YOUR
back guarantee.
SIMPLE AND INEXPENSIVE do-it-yourself
electronic projects suitable for teen-agers.
Louis L. Colen, 2727 Krim Dr., Los Angeles,
Calif. 90064.
CASSETTE REJUVENATION Those priceless
jammed cassettes can be repaired!! Send for
details. RAP Associates 31 Greenwood Road,
Andover, Mass. 01810.
MAKE FRIENDS, Write Worldwide Tapespondence, 218 Montrose St., Philadelphia, Pa. 19147.
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 'ánd Surplus Categories Catalog $1.00
(Deductible On Orders From Separate Included
Catalog).
Surplus
Service,
Box
820 -AUD,
Holland, Michigan 49423.
.
.
.
TRAVEL RESORTS
MONT TREMBLANT LODGE & Ski Area, Mont
Tremblant, P.Q. Best skiing in Eastern America.
Ski Weeks, weekends & group rates. For information and reservations Tel. (819) 425-2711
or Mtl. 861-6165. For snow reports Mtl.
recorded tapes.
York 10931.
unwanted
Record
House,
LP's
and
Hillburn,
pre-
New
JBL LE -85 Driver 16 Ohms, Albert Yoncha,
242 Fox Rd., Media, Pa. 19063.
HARD to find show and soundtrack LP's. List
100. Music Minstrel, P.O. Box 15271, New
Orleans, La. 70115.
COLLECTORS JOURNAL -VALUABLE DATA,
RECORD MART 12 issues $3.00 -Record Research, 65 Grand Ave., Brooklyn, New York,
SITUATION WANTED
LIBRARIAN -MIS (Columbia). Sound Collage,
Sound Track, Multi -Media production my specialty.
Seek position with recording company or FM
studio. Adept at organizing information, resources.
For resume, references. Write: Harry Roger
Williams 3rd, 226 W. 242 St., Apt. 4G, Riverdale,
N.Y. 10471.
AUTHORS WANTED BY
NEW YORK PUBLISHER
Leading book publisher seeks manuscripts of all
types: fiction, non-fiction, poetry, scholarly and
juvenile works, etc. New authors welcomed. For
complete information, send for free booklet R-55
Vantage Press, 616 W. 34 St., New York 10001
Check No. 80 on Reader Service Card
Lowest
of the
LOW!
Reprise
label, or tape. Ledford, 173 West Ann Arbor,
Pontiac, Michigan 48055.
WANTED: Eico HF60 basic. amp, Rek-o-kut
B16H turntable, Presto T-18 turntable. Will pay
top price for any of these. Mr. Chris Hood, 11 E.
Prospect Ave., Pittsburgh, Pa. 15205.
WANTED: Acrosound 120 or Realistic 210
Amplifier. Stephens 214 tweeters. Box 1016,
Church St. Sta., New York City.
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. 95401.
BIG BANDS OF THE THIRTIES & FORTIES,
ORIGINALS, CASSETTES 90 MINUTES $6.00.
DALE McCLESS, Box 122C RR# 4, Swanton,
Ohio 43558.
Shamelessly Low Prices..
As one of America's largest wholesale
distributors, we're guilty of shamelessly
low prices. Our buying volume has
made our prices the lowest. We
seriously doubt you can find one lower
.. and that we're proud of. What's
more, at S.C.A. you can select from
hundreds of NEW, Factory Sealed,
Full Warrantee, Brand name,
Ii -Fi
Stereo components. If its in the 1i -Fi,
Audio field
we have it!
Write for a lowest of the low quote ..
...
we're not ashamed.
STEREO CORPORATION
BUSINESS OPPORTUNITIES
NOVELTIES
MUSIC
BOXES -Movements. Finest.
Spielman, 131 West 42nd, New York 10036.
AUDIO
258-5121.
WANTED: MORT SAHL RECORDS,
861-1925.
SWISS
OLDIES -45 RPM original labels and represses
over 5,000 from personal collection for sale.
Reasonable prices. Try me for the ones you've
given up hope in finding. Call or write, Robert
Fenster, 1503 Ave. J, Brooklyn, N.Y. (212)
11205.
HIGH FIDELITY SPEAKERS REPAIRED
AMPRITE SPEAKER SERVICE
655 §ixth Avenue, New York 10, N.Y.
AUDIO MIXERS engineered to your specifications.
Input flexibility including equalization, gain, pan
and switching. Modular construction with plugin cards for easy changes. Nueva Engineering,
Box 161, Glen Burnie, Md. 21061.
OLDIES -45 RPM. Original hits. Catalog 500.
C & S Record Sales, Box 197, Wampsville, N.Y.
13163.
OUR 25th YEAR
MAIL ORDER! Make
$
15 per hour working home.
Free report reveals millionaire's secrets! Executive
(1012). 333 North Michigan, Chicago 60601.
JANUARY 1972
Dept A, 2122
BROOKLYN,
of AMERICA
UTICA AVENUE,
NEW YORK
11234
(212) 338-8555
In L.I. 1180 HEMPSTEAD TPK, UNIONDALE
Check No. 81 on Reader Service Card
81
www.americanradiohistory.com
Hear it like it is:
EDWOOD
Advertising Index
TEREO
OM11PANY
Western High Fidelity Wholesalers
DISCOUNTS
ON
NATIONALLY ADVERTISED
HI-FI STEREO
COMPONENTS
ONLY RSC OFFERS:
Low Eastern Prices
Lowest Shipping Costs
Fastest Delivery
FOR A RUSH QUOTE WRITE:
C
P. O. BOX 2794
SAN RAFAEL, CA. 94902
Telephone ,415, 472 3447
RSC
-
35
Acoustic Research, Inc.
71
Allied Radio Shack
15
Altec Lansing
7
Ampex Corp
46, 47
Audio Dynamics Corp.
82
Audio Sales
14
B&W speakers
6
Benjamin Electronic Sound Corp
21
Bose Corp.
5
Bozak Mfg. Co., R. T
36, 37
British Industries Corp.
33
Crown International
71
Downtown Audio Inc.
Dual turntables
Dynaco, Inc.
Electro -Voice
Elpa Marketing
Empire Scientific Corp.
Fairfax Industries, Inc
Fisher Radio Corp.
Frazier, Inc
Garrard turntables
Heath Co.
KLH Research and
Development Corp.
Lafayette Radio
Electronics Corp
Linear Devices, Inc
27
8
73
Cover III
28
59
25
70
36, 37
52, 53
43
74
14
Marantz Co.
Matsushita Electric Corp.
Maximus Sound Corp
McIntosh Laboratory, Inc.
Metrotec Industries, Inc.
PE turntables
Panasonic
Phase Linear Corp.
Pickering & Co., Inc.
Pioneer Electronics
Redwood Stereo Co.
Cover IV
11
77
14
70
Cover III
11
.75
17
13
82
49
Roj an
Sansui Electronics
Schwann, Inc.
Scott, Inc., H. H
Sharpe Audio Div.,
Sintrex
Sherwood Electronic Labs
Shure Brothers, Inc
Sony Corp. of America
Soundcraftsmen
Stereo Component Center
Stereo Corp of America
Superscope, Inc
TEAC Corp. of America
Thorens turntables
United Audio
Vantage Press
3
69
Cover II
2
9
51
30, 31
63
81
81
22, 23
1
Cover III
27
81
Best in the West
SELL FOR LESS
Nafiionally Advertised Brands
Hi-Fi Stereo Components
Tape Recorders
Record Changers
Home & Car Stereo Tapes
Speaker Systems
Radio & TV Sets
Electronic Equipment
BRAND NEW
AND FULLY GUARANTEED
WE CAN SAVE
YOU MONEY
(Continued from page 10)
cert-hall acoustical characteristics are
played back through speakers which
duplicate the acoustic response of the
concert hall, the response curve is compounded. A slope of 5 db at the high
end therefore becomes a slope of 10 db,
creating an unnaturally dead high -end.
The only reasonable and logical conclusion is that the speakers used in a
stereo system should be capable of as
nearly flat response as possible. If the
speakers themselves are not capable of
flat response, use should be made of
tone controls or narrow -band equalizer
controls to make the net system response as flat as possible. If an imposed
effect is called for, concert -hall or
otherwise, the controls can be readjusted.
Philip E. Bond
Teaneck, N.J.
AUDI
Mr. Allison will have an opportunity
to reply in the next issue. In the meantime, I would certainly challenge the
assertation that the engineer mixes for
the most realistic sound. Not necessarily!
He may mix to produce that which, in
his opinion, gives the most realistic
sound under domestic conditions. Or he
may aim for an exaggerated stereo effect,
or he may try to achieve an exciting but
2745 ERIE BLVD. EAST
SYRACUSE, NEW YORK 13224
82
SEND:
for FREEllzfing
of 1000's of items
...
LOWEST PRICES ANYWHERE!
iodory Seated Un.rs
For/ Servrce
unrealistic sound It all depends....-Ed.
AUDIO
Check No. 82 on Reader Service Card
www.americanradiohistory.com
You'll have a storehouse of
stereo information and ideas
when you save Audio in a
handsome library case. Attractive and durable in rich,
simulated leather with 16K
gold embossed lettering, it
will protect your entire
year's collection of Audio.
Available at $3.50 each, 3 for
$10. Satisfaction unconditionally guaranteed or your
money back. Send order
with check to:
AUDIO
134 N. 13th St./Phila., Pa. 19107
OUR 25th YEAR
JANUARY 1972
READER INQUIRY CARD
Use this FREE Post Paid Card for more facts
on the products described and advertised in
this issue.
JANUARY 1972 ISSUE
THIS CARD EXPIRES MARCH 31, 1972
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80
94
95
109
124
35
110
125
36
51
81
22
37
52
112
126
127
53
113
128
24
38
39
114
129
10
25
40
96
97
98
99
100
111
23
63
64
65
66
67
68
77
78
92
48
49
50
115
130
11
26
41
12
27
42
13
28
43'
14
29
44
15
30
45
16
31
2
17
32
3
18
33
4
19
34
5
20
21
7
8
9
82
83
54
55
56
57
58
69
70
84
71
101
116
131
102
117
132
103
118
133
59
60
74
86
87
88
89
104
119
134
75
90
105
120
135
72
73
85
A
B
My Comments On This Issue
equipment after seeing it advertised
following equipment
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In the next year.
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The best
of both whirls
For manual play, experts and hi-fi enthusiasts agree the most esteemed name in transcription turntables is Thorens. Among automatic turntables, PE offers unparalleled value.
Perfection in performance. At better hi-fi dealers everywhere. Distributed exclusively by:
Elpa Marketing Industries, Inc., New Hyde Park, N.Y. 11040/Scottsdale, Ariz. 85253
Check No. 3 on Reader Service Card
www.americanradiohistory.com
A Marantz speaker system
breaks up that old gang of yours.
Separation of sound is a true test of a speaker system.
And to put Marantz-or any speaker-to the test you should
listen to something you are already familiar with
so you'll be able to hear for yourself that it's the
speaker and not the recording that makes the
difference. Oh, what a difference Marantz makes!
What you thought were two oboes are now clearly
an oboe and a flute and that barbershop quartet...
well, they're really a quintet.
Let's face it: most speakers look the same, most
speakers have an impressive list of specifications
and ALL-ALL-ALL speakers claim to be the
very A-1 HOT SHOT MOSTEST BEST.
But the proof is in the listening. And that's
where the Marantz Imperial 5 comes in. The
Imperial 5 is engineered to handle a plethora of
continuous RMS power and has an accoustic
suspension woofer and tweeter with a fantastic off -axis response and a 3 -position high frequency control and costs
just $89 and gives you true stereo separation
anywhere in the room and is, for the money, truly
the very A-1 HOT SHOT MOSTEST BEST.
But on paper so is theirs.
However keep this in mind. Marantz speaker
systems are built by the makers of the most
expensive stereo equipment in the world. And
exactly the same quality that goes into Marantz
receivers and Marantz amplifiers goes into the
Marantz Imperial 5 speaker system.
To find out how much better it sounds, listen.
That's all we ask. Listen. Then ask about the big
savings on a complete Marantz system.
>f1'1
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We sound better.
Check No. 43 on Reader Service Card
cMarantz Co. Inc.. P.O. Bon 99C Sun Valley. Catit 91352.
.
M
arantz S
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A
40. Rue de Chatelain.1050 Brusºels. In Canada'. Electrohome. Ltd Send for tree catalog.

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