null  null
the authoritative magazine about high tide!ity
geofe..-ON SALE
The Truth About Stereo Amplifier
Power Ratings!
Be Your Own Critic of Synth size
Also: ABZs of FM, Tape Guide, Audioclinic
If you could look through your speakers,
is this what you'd see?
Listen carefully. Chances are your speakers add their own
distorting coloration to the music. Maybe it's a boomy bass,
or an overemphasis on treble. Most speakers do it, and some are
designed to do it. You may not even mind the effect. But is
this really the absolutely faithful reproduction you paid for?
If you enjoy adding emphasis to selected parts of the music,
that's your prerogative. But don't let your speakers do it for
you! There are controls on your receiver or amplifier that do
the job much more predictably and pleasingly.
The best speaker is still the one with absolutely even response; with no coloration of the highs or the lows. This is
the kind of speaker that Scott makes.
Scott engineers design every component part of Scott
speaker systems. It's far more difficult than using ready-made
components, but Scott won't accept the bias built into "off the -shelf' parts. Scott's Controlled Impedance speakers are
designed specially for use with today's solid-state equipment.
Custom -designed woofers, tweeters, midranges, and cross -over
circuitry are carefully matched in solid, air -tight enclosures.
And each individual speaker system must survive the scrutiny
of both electronic instruments and trained ears before it's
allowed to leave the Scott factory.
As a result, Scott speaker systems are completely honest;
what goes into them is what comes out of them. They won't
cover up for a poor receiver or turntable. Neither will they
distort the perfection of a good component system. And that's
what Scott believes great speakers are all about.
Choose from five Scott Controlled Impedance speaker systems, priced from $49.95 to $274.95, at your dealer's.
H. H. Scott, Inc., Dept. 35 -04
Maynard, Massachusetts 01754
Improve your listening with Scott 20/20 Speakers.
© 1968,
H. H. Scott, Inc.
Vol. 52, No. 4
Successor to
Est. 1911
Associate Editor
Production Manager
Subscription Manager
Rossini vs. Rossini
Build a Sheet Metal Reverberator
ABZ's of FM-FM Broadcasting
Sound & Decor Styles
Transistors: 20 Years Old
More About Negative Feedback, Part 3
AES West Coast Convention Program
Ralph Hartz &
Fred Kamp
24 Lewis A. Harlow
28 Edward Tatnall Canby
28 Robert Ehle
32 Leonard Feldman
42 Norman H. Crowhurst
Light Listening
Jazz and Blues
64 Edward Tatnall Canby
70 Stuart Triff
72 Bertram Stanleigh
Crown Professional Tape Recorder
AR Stereo Integrated Amplifier
Garrard Automatic Turntable
48 Model CX822
57 Model SL -95
What's New in Audio
Tape Guide
Audio, E.T.C.
Editor's Review
Advertising Index
Joseph Giovanelli
8 Herman Burstein
12 Edward Tatnall Canby
AUDIO (title registered U. S. Pat. Off.) is published monthly by North
American Publishing Co., I. J. Borowsky, President; Frank Nemeyer, C. G.
McProud, and Arthur Sitner, Vice Presidents. Subscription rates-U. S.
Possessions, Canada, and Mexico, $5.00 for one year; $9.00 for two years;
all other countries, $6.00 per year. Printed in U.S.A. at Philadelphia, Pa.
All rights reserved. Entire contents copyrighted 1968 by North American
Publishing Co. Second class postage paid at Philadelphia, Pa.
REGIONAL SALES OFFICES: Sanford L. Cahn, 663 Fifth Ave., New York,
N. Y. 10022; (212) 753-8824. Louis Weber, 2927 W. Touhy Ave., Chicago,
III. 60645; (312) 743-1206. Jay Martin, 9350 Wilshire Blvd., Beverly
Hills, Calif.; (213) 273-1495.
Warren Birkenhead, Inc., No. 25, 2-chome, Shiba Hamamatsu -cho, Minato-ku, Tokyo, Japan.
AUDIO Editorial and Publishing Offices, 134 N. 13th St., Philadelphia, Pa. 19107
Postmaster: Send Form 3579 to the above address.
E- Check No. 100 on Reader Service Card
Chief Engineer,
Marketing Director
The Truth About Stereo
Power Amplifier Ratings
How to Be Your Own Critic
of the New Synthesized Music
Number 55 in a series of discussions
by Electro-Voice engineers
Art Director
Contributing Editors
April 1968
With the exception of a handful of "ultimate"
loudspeakers, most high fidelity speaker systems are designed to be produced profitably at
a specific selling price. While there is nothing
inherently wrong with this restriction on design,
difficulties can be encountered if an equal emphasis on value is not stressed.
The temptation, of course, is to provide as
many features (or apparent features) as possible in the system so that it is most attractive
to potential purchasers. But if allowed to dominate the design, this attitude can spell poor
value for the consumer.
An example of this problem is the comparison
of two systems of equal price on the basis of
the number of speakers employed. While unsophisticated buyers may feel that "the more
speakers the merrier," more often the reverse
is true when the design has been limited to a
specific price. In part, the reason is purely
economic. A 10" 3 -way system selling for
$80.00 will likely have less investment in each
speaker than an equivalent 10" 2 -way design
selling for the same price.
And the difference is not limited to dividing
the speaker cost by 3 instead of 2. In addition, components such as crossover network
elements, level controls, wire, and increased
assembly costs needed for the more complex
system reduce the money available for the
speakers themselves.
A more complex system also introduces more
opportunities for quality variation in produc-
tion. Each added component increases the number of tolerances that must be maintained (and
these tolerances tend to broaden as cost is
reduced). If high quality is to be maintained,
the design time for a complex system must
also be increased over that of the simpler
model. A number of problems, unique to multiway systems, must be studied. These problems
increase with each added speaker.
Examples include the difficulties encountered
when two or more speakers reproduce the same
frequency (as at the crossover frequency, for
example). Another area of concern to the engineer is the problem posed by two speakers
reproducing different ranges of the same instrument (with the fundamental tone coming
from one speaker, while overtones are reproduced from one or more others). Addition of
speakers to the system increases the opportunity for difficulty.
Where cost is a limiting factor, a simpler system generally has more potential for satisfactory performance, all other factors being equal.
By concentrating more time and money on
fewer components, both in design and manufacture, each element is more likely to contribute maximum value to the system. In the final
analysis, the number of speakers in a system
may be an inverse guide to its quality.
For reprints of other discussions in this series,
or technical data on any E-V product, write:
602 Cecil St., Buchanan, Michigan 49107
Check No. 101 on Reader Service Card
ing even the smallest groove variations
Coming in
Audio clinic
Batteries for Tape Recorders
Walter Salm examines the variety of batteries used to power
portable tape recorders.
The World of Outdoor Hi-FiWith summer almost upon us,
here is a timely roundup of
audio equipment designed for
outdoor use.
Receiving Antennas Len
Feldman takes some of the mystery out of antennas used for FM
receivers in this installment of
ABZs of FM.
Music of the Twenties & Thirties Re-Visited-Stuart Triff discusses recent reissues of old
recordings made in the Twenties
and Thirties by Crosby, Merman,
and others.
... And
Model Five Twenty Stereo FM Receiver
Sony/Superscope Model TC-230
Stereo Tape Recorder
Plus: Regular monthly columns
on music and equipment.
ABOUT THE COVER-The first transistors,
developed more than 20 years ago, were
primitive by today's standards. The plastic packaged transistors illustrated on the cover
of this issue, high -power silicon transistors
from RCA Electronic Components and Devices, are shown as an assembly of 60 36 -watt
transistors and an assembly of 80 83 -watt
transistors before they are cut apart to form
individual devices. This construction technique is used so that plastic may be fed
into molds.
If you have a problem or question on
audio, write to Mr. Joseph Giovanelli
at AUDIO, 134 North Thirteenth Street,
Philadelphia, Pa. 19107. All letters are
answered. Please enclose a stamped,
self-addressed envelope.
Styli and records
Q. I am considering the purchase of
a new cartridge. My present one does
not track as well as it could (confirmed by borrowing cartridges from
friends.) I am interested in the least
record wear as well as good reproduction. My record collection is about 90
per cent stereo. That percentage will
go higher as I add to the collection. I
have considered two cartridges in separate, plug-in heads for the two types of
records. I wonder if this is necessary.
My concern is over the styli available, both elliptical and conical. Can
they both be equally good for the records?
Will you clear up some of my confusion by suggesting which is the more
desirable type and size for the two
types of records. I will appreciate any
assistance you can give me.-Paul E.
Scraggs, Clark, N. J.
A. As you know, some cartridges are
designed to complement fairly poor
equipment. They are massive compared to the better cartridges. Therefore, they track at heavier forces than
the better cartridges. As the tracking
force increases, record wear will increase, given the same stylus configuration in all cases. However, if we
increase the stylus dimensions, the
amount of tracking force will be spread
out over a larger surface, meaning that
the record will take less of a beating.
Cartridges and arms are improving
all the time. We now can think in
terms of tracking forces which are less
than one gram in a few instances. This
means that we are now in a position to
employ styli having small dimensions,
indeed. We would want to use such
styli because they are capable of enter-
and tracing them properly. The result
is less distortion and better high frequency response, even at the center
portion of the disc.
If we take a conical stylus, we finally
arrive at a dimension which will be so
small that the actual stylus tip will rest
on the bottom of the groove. This is a
state of affairs we do not want. We are
not concerned with the bottom of the
groove. The information we want to
recover is in the groove walls. If the
stylus rests at the bottom of the groove,
it is not free to move easily. Further, it
is obvious that some noise will be
added, merely by the fact that the
stylus contacts areas of the discs which
are contributing noise but no desired
program information.
If, now, we make the stylus elliptical,
we have the best of two worlds. We
have a stylus of small dimensions
which will trace all groove variations.
However, the stylus is wide enough
from left to right so that it cannot fall
into the groove completely. The sides
of the stylus must come to rest on the
wall of the groove before the tip can
touch the groove's bottom.
Remember that the amount of force
bearing down on the walls is quite large
with an elliptical stylus because all of
it is concentrated on two very small
points. An elliptical stylus will therefore cause severe record wear if the
tracking force is not reduced to compensate for this added force. Today's
cartridges are capable of tracking at
forces small enough to keep record
wear very low and still track better
than anything we have previously
If you have an old changer, you will
not be able to make use of one of the
newer types of cartridges. However,
you can still find one which will work
well for you and keep wear to a minimum.
I would imagine that if you must
track your cartridge at more than 2
grams because of troubles in the mechanical portion of the changer, you
should not use an elliptical stylus.
If you have a good stereo cartridge,
it will play your monophonic records
better than most any monophonic cartridge that was available when monos
reigned supreme. If you use a spherical
(conical) stylus, you should think in
terms of a diameter not less than 0.7
mil. This has nothing to do with record wear, but has to do with the fact
that many monophonic recordings
were made with a somewhat wider
(Continued on page 4 )
Check No. 3 on Reader Service Card
After dinner, light up a Garrard
You snap tie illt_minand switch of your
3arrard Dower Ulatic 3ase, sit tack and -elax.
You've put a demanding record on the ft.-I-able, bit you haven't the slightest aopreheisicn about what you're going to hear. You know
-hat the Garrarc SL 95 will track any cartridge
to bring out everything the recording contains
The perfectly balanced tra- ow mass tone
arm, the precision stylus fcrce setting all :Fe
i-ska ing co-upensation nsure it. The ow -sized turntable is ma:chec to Garrard's sinch-onous motor to give you absolutely coistant
record speed, ulwave-ing etch. The soouisticaled, yet simp e controls permit you to cue and
pause, safely and accurately. Now the music
comes to a crescerdo that you know would be
beyond the caoacit, of lesser units to trackanc your confiderc- in the Garrarc is justiriec
once again. -Fe sound comes clear, pure.
whole, in all i:s original integrity. It's a thril
that only 3 true of gcod sourd can ex
perience. Garra -d is made for Ca: listener
-he SL 95. 3_ $129.50 less base anc
cart-idge. is one of four in Garrard's new
Synchro-Lab Series " of automatic turntables
priced fron S59 5O Cther Garrard models from
$37.50. Opt one! P:wer-Mat c Base is $15.95
For comol men_ary Comparato- Guide describing all the new Garrard models, w-i:e
Garrard, Dept. ;D-5, Westbury, N.Y. 11590
groove than is used today. Stylus diameters smaller than 0.7 mil may re-
onck yabora
outrater of
of record'
t he nea
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to oui
sult in the stylus bottoming in the
groove of some monophonic discs.
The same holds true for the elliptical
stylus. Its major axis should not be less
than 0.7 mil. Again, this is not so much
a question of record wear as it is one
of groove geometry. The only question
lies in the ability of the cartridge to
play properly some older monophonic
Because some music and performers
are available on monophonic discs
only, you always want to keep the
above in mind. All too often we think
only in terms of the stereo effect or
whether the sound is good. True, these
considerations are of interest to us as
serious listeners. However, some performers just did not make records
when stereo was finally on the scene.
Maybe the fidelity of these recordings
is not good, even for monophonic recordings. If the artistry is great
enough, let's forget high fidelity and
concentrate on the beauty of the performance rather than on the fact that
it might not have much high frequency
response above 5 kHz.
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"The 64X offers the highest
caliber of performance
presently obtainable
in a home tape recorder
...we could not find
fault with it in any respect. "t..
The Tandberg 64X sells
for $549 and is well worth it: tlpti
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Berlitz Language Cassettes
Language phrases from famed Berlitz Phrase Books have been assembled
in tape -cassette form. Five languages
are offered in this form: French, Italian, German, Spanish and Russian,
each with up to 50 minutes of basic
phrases. Each of the pre-recorded cassettes is priced at $6.95.
Industry Changes
The Tandberg Model 64X
four -track tape deck is the choice
of experts. Find out why.
Write us for your free copy of the
Hirsch -Houck Laboratories report.
For better, clearer
more natural sound...
jl andbery
Check No. 4 on Reader Service Card
Victor J. Amador upped to vice
president of BSR McDonald. Russ
Molloy, founder of Bel -Canto Stereo
Tapes in 1954, joins Telex. Thomas
J. Nicholson appointed executive vice
president and general manager of Vega
Electronics. Donald H. Palmquist advanced to marketing manager at Altec
John H. Trux appointed
vice president of marketing for Bell &
Joseph S.
Howell's tape division.
Tushininsky, chairman and president
of Superscope, Inc., assumes similar
responsibilities for its subsidiary, Marantz Inc.
APRIL 1968
High price does not guarantee high quality. The Studio Pro 120 at $379.50** is
equal or superior to many receivers costing up to $600.
Here's why.
By designing around the most advanced electronic devices commensurate with
the state of the art such as, MOSFET front end, integrated circuits, all silicon
transistors, encapsulated circuit breakers, 98 semi conductors, etc., we have
built in all the quality that is possible for anyone to achieve. By developing new
production line techniques with computer controlled material flow, we have
been able to establish the exciting price and quality of the Studio Pro 120.
Each Studio Pro 120 has its individual quality control program supervised by
the most demanding engineers in the business. Each will live up to the claims
we make. We had the specifications certified by two of the nation's leading
independent testing firms so you can believe them implicitly.*
Stop by your University dealer today and hear this great new pacesetter in
the receiver world. Write desk D-83
**Manufacturer's suggested resale price.
9500 W. Reno
Oklahoma City, Oklahoma
*AMPLIFIER SECTION: IHF Power Output: 120 watts total, IHF Standard at 0.8%
4 ohms (60 watts per channel). RMS Power Output:
ohms:30 watts per channel at 0.3% THD. Frequency Response: +0, -3 dB from 10 THD,
Hz to 100 kHz. Power Bandwidth: 30 Hz to 40 kHz, IHF Standard. Intermodulation Distortion: Less than 0.5% at any combination of frequencies
up to rated output. Tone Control Range: ± 18 dB at 20
Hz and 20 kHz. Damping Factor: 50 to 1. Noise Level: (Below rated output) Tape monitor: -83 dB-Auxiliary:
-80 dB-Phono: -60 dBTape Head: -63 dB. Input Sensitivity: (For rated output) Tape Monitor: 0.4 Volts-Auxiliary:
0.4 Volts
Tape Head: 1 mV at 500 Hz?hono: 4 mV at 1 kHz. Input Impedance: Phono and Tape Head: 47,000 ohms-Tape Monitor:
10,000 ohms.
Load Impedance: 4 to 16 ohms. FM TUNER SECTION: Sensitivity: 1.6µV for 20 dB of quieting, 2.3
for 30 dB of quieting, IHF. Frequency
Response: ± 1/2 dB from 20 to 20,000 Hz. Capture Ratio: Less than 1 dB. Image Rejection: GreaterµVthan
Greater than
90 dB. Separation: 40 dB at 1 kHz. Selectivity, Alternate Channel: 55 dB. Drift: .01%. Distortion: Less
than 0.5% at 100% modulation ± 75
kHz deviation. Multiplex Switching: Fully automatic logic circuit. GENERAL: Dimensions: 41/2" H x 163/e"
x 12" D (including knobs).
Weight: 17 lbs. Amplifier Protection: Three 1 -ampere circuit breakers. Complement: 31 Silicon & MOSFET Wtransistors,
21 Diodes, 2 Integrated circuits (each containing 10 transistors, 7 diodes, 11 resistors).
University is the proprietary trade name of University Sound © 1967
r uDIO APRIL 1968
Check No. 5 on Reader Service Card
Each deck incorporates a three -digit
tape counter with pushbutton reset,
pause control function, and two VU
meters, and includes an oiled -walnut
Check No. 60 on Reader Service Card
Neumann "FET-80"
Condenser Mikes
Gotham Audio Corp., N. Y., announces a new series of Neumann condenser microphones, called "FET-80."
The FET-equipped microphones include solid-state versions of well-known
tube -equipped counterparts. The model
Introduces Tape Decks
The reproduction of
true sound is the sole
purpose of a Klipschorn loudspeaker.
You'll like the sounds you hear from
a Klipschorn only if you like the
sounds that were recorded. It has
no sound of its own. If you're looking
for exaggerated bass, sensational
treble, or dramatic "hi-fi" effects,
don't depend on your sound reproducing system, tell the recording
artists. Strictly speaking, there is no
such thing as "high fidelity;' only
"fidelity" or "infidelity:'
Our speakers are designed and built
for but one purpose-fidelity.
They're built in Hope, Arkansas,
under the personal supervision of
Paul W. Klipsch by a small group
of dedicated craftsmen. They're sold
by dealers who are concerned that
you get a system with fidelity.
Harman-Kardon has expanded into
the tape -deck field with two 3 -speed,
4 -track, open -reel units, Models TD -3
($199.50) and Model TD -2 ($149.50).
Model TD -3 features three tape
heads for separate record, playback and
erase, while the TD -2 has a two-head
assembly for record/playback and
erase. Among the other features accounting for the TD -3's higher price
are sound -on -sound and tape monitor
facilities, and a hysteresis -synchronous motor.
The TD -3's one -micron gap playback head gives the machine extended
high -frequency playback capabilities.
According to the manufacturer, the
BOX 280 A-4
Please send me the whole truth about the
KLIPSCHORN loudspeaker system. Also
include the name of my nearest Klipsch
authorized audio expert..
City ..
DEnclosed is $3.50 for a complete set of
17 technical papers on sound reproduction and stereo.
TD -3's frequency response range is 30
to 22 kHz at 71/2 ips, 30 to 15 kHz at
33/4 ips. This compares with the TD -2's
30 to 20 kHz and 30 to 13 kHz, at respective speeds.
Signal-to-noise ratio for both decks
is said to be 50 dB; wow and flutter is
under 0.1% at 33/4 ips; cross -talk, better
than 60 dB. Bias frequency is 96 kHz.
Both models are compactly designed,
measuring 11% -in. W x 92/3 -in. H x
6 -in. D. Weight is 16 lbs. Equalization
is set automatically for each speed.
U-87, successor to tube model U-67, is
a 3 -pattern switchable microphone with
additional switches for overload protec-
tion and proximity correction; model
KM -84, the "FET-80" successor to
tubed model U-64, also has another version, KM -84, which features low frequency roll -off for close-miking
applications and for public address use.
The Neumann KM -86, a miniature 3 pattern side -addressed microphone, is
the successor to the "Linear Admitance" KM -66.
The Neumann "FET-80" microphones are available in systems powered from the N-452 dual microphone
a.c.-powered unit or the BS -45 battery supply accessory. The condenser element polarizing voltage is obtained
directly from the supply voltage; r.f.
circuits are not used.
Also introduced is a condenser lava lier microphone, designed for high quality broadcast interview and film
sound "fish pole" applications. It is
normally equipped with the cardioid
KM -85 capsule with low frequency
rollcff, but can be delivered with full
low -frequency response with a KM -84
Check No. 62 on Reader Service Card
Check No. 6 on Reader Service Card
APRIL 1968
Meet the
"Copy Cat"
The New Sony Model 155
Playback/Dubbing Stereo Tape Deck!
If you now own a stereo tape recorder, you can become a "copy cat" for only $99.50 For the cost of about fifteen prerecorded tapes, you can own your own complete 4 -track stereo tape duplicating system and build a fabulous stereo tape
library at a fraction of the cost of pre-recorded tapes! The Sony Model 155 is a complete stereo transport deck with solidstate playback pre -amplifiers specifically designed to be used together with your present stereo tape recorder for dubbing!
The Model 155 has features and performance never before heard of at under $100.00! For example
Three speeds
Special filter for virtually flutterless performance
Retractable pinch roller to permit tape threading with one hand
Stereo headphone jack for private listening, and
the flexibility of vertical or horizontal operation! These are
all features normally found on only much higher priced equipment.
The Model 155 can also be used just for stereo
tape playback through your existing components or package stereo music system. Imagine
Sony quality true -fidelity
stereo tape playback for under $100.00! Complete with handsome walnut finish, low -profile base and optional dust cover.
Let the Model 155 Playback/Dubbing Stereo Tape Deck make a "copy cat" out of you! And, as always . . you can
count upon the extraordinary "Sound of Sony"!
The Topewey to
Check No. 7 on Reader Service Card
APRIL 1968
New from
Tape Guide
FET-80 Series Microphones,
with Compatible Central Powering
Good news for people who wanted the
finest, but couldn't afford it. Now you
can obtain the new Neumann micro-
phones-solid state and still unchallenged for acoustical quality-at prices
up to 30% lower than before.
Using advanced transistor electronics, FET-80 Series Microphones
enable you to enjoy famous Neumann
performance, plus the flexibility of
central compatible power, long -life
battery operation; two-year guarantee,
and more. All at tremendous savings.
FET-80 Series Microphones are currently available in four models, priced
from $276 to $418.
Free from
Information that tells all about them.
Gotham is the sole U.S. distributor of
Neumann microphones, so we know
more about them than anyone else.
Mail the coupon below, and we'll send
you an illustrated brochure describing
Neumann's new FET-80 Series Microphones. We'll also send you an informative technical article that you'll refer
to often. The supply is limited. (It
really is!) So write today.
Gotham Audio Corporation
2 W. 46th Street, N.Y., N.Y. 10036
Please send me your free brochure and
article describing Neumann's
FET-80 Series Microphones.
Check No.
If you have a problem or question on
tape recording write to Mr. Herman
Burstein at AUDIO, 134 North Thirteenth Street, Philadelphia, Pa.19107.
enclose a stamped, selfPlease
addressed envelope. All letters are
Tape copying
Q. When copying a tape, what are
the best volume control settings for the
playback machine and for the recording machine?-Jerry L. Porter, North
Bend AFS, Oregon.
A. The optimum settings of the playback and recording gain controls depend on their location with respect to
preceding and following electronic
stages. If the playback gain precedes
an electronic output stage, a high setting is desirable to maximize the ratio
of audio signal to noise of this stage.
If the playback gain control is at the
very output, its setting is immaterial
so far as S/N of the playback machine
is concerned. Of course, we assume that
the playback machine still delivers
enough signal to drive the recording
If the recording machine's input jack
(high-level) goes directly to the recording gain control, with no intervening electronic stage, then it is
immaterial what setting of this control
is used (assuming there is no significant high -frequency loss at mid -setting
of the control, as sometimes happens
with poorly designed amplifiers). The
control will always be set so that the
same amount of signal is delivered to
the following stages to achieve proper
recording level. But if an electronic
stage precedes the recording gain control, you may have the problem of
finding an optimum setting: too much
input signal may overload the first
stage; too little input signal may result in too low a ratio between the input signal and noise of the first
recording stage. If you know from the
recording machine's specifications, or
through experience or other means,
that the first recording stage will not
overload even for signals much greater
than can be delivered by the playback
machine, it would be safe to set playback gain at maximum to achieve maximum S/N with the recording machine.
In the absence of specific knowledge
about the playback and recording machines' design and signal -handling
capabilities, the safest thing is to start
with the playback and recording controls in about mid -position. Then let
trial and error and your ears guide
TV sound, again
How may one feed TV sound into a
tape recorder? This question has been
asked before and continues to be asked.
The problem gets especially knotty if
the TV set has no isolating transformer, but goes directly to the 117 V a.c.
supply. Reader Ir. H. N. Hansen (of
Laren Nh., Holland) has the suggestion
shown in the accompanying sketch. A
1:1 isolating transformer (in his case,
Philips A3-161-86-1) is placed across
the volume control. The 100K resistor
prevents undesirable loading of the FM
detector. And the 5K resistor presents
a small source impedance that permits
a fairly considerable length of cable to
the tape recorder-perhaps as much as
40 or 50 feet of low -capacitance microphone cable. Because the signal across
the 5K resistor will be quite small, the
signal must be fed into the microphone
input of the tape recorder. However,
one could use a larger resistor in place
of the 5K one to obtain more signal,
perhaps enough to drive the tape recorder through its high level input,
with a consequent improvement in sigSound takeoff from TV set, as outlined by
Low -capacitance microphone
microphone input of amplifier or
Iso ating
nal-to-noise ratio. At the same time,
increasing the value of this resistor
would require a shorter cable in order
to avoid high frequency loss.
Writes Reader Hansen: "I am getting superb hi-fi TV sound in this way.
The tape recorder is permanently connected to the hi-fi amplifier, so this
setup is a solution to the taping problem. In other words, the TV set has
become a component of my audio sysÆ
on Render Service Cord
APRIL 1968
Suddenly it's 1969..
Look closely at this photograph and
db; flat frequency response from 15
you will notice four Integrated -Circuit'
components which are part of the IF
section of the new Sansui MID 5000
solid state, stereo receiver. These
small hat -shaped objects are filled
with a number of diodes, transistors
and resistors integrated into a functioning sub -miniature circuit They are
just one of the latest advances introduced by Sansui along with such ad-
The MD 5000 includes output con-
nections for three separate sets of
stereo speaker systems which you can
select separately or in pairs. In addition to inputs for tape, phono and
auxiliaries, Sansui gives you extra input and output tape connections for
vanced audio circuitry as the specially
selected FET FM front end. Consider
these specifications: 160 watts IHF
music power (75 watts per channel
continuous power); 1.81N sensitivity;
selectivity better than 50 db at 98
MHz; stereo separation better than 35
34-43 56th Street
Sansui Electric Company, Ltd. Tokyo, Japon
APRIL 1968
*If you are not sure what Integrated
Sansui Electronics Corporation
recording or playback using extra recorders. You may monitor tape machine 1 or 2 from front panel when
you record through your Sansui receiver
all the features which will
make it the nucleus of your most
comprehensive hi-fi music system
for years to come. This new Sansui
MD 5000 has been created for the
sophisticated connoisseur who demands the u'timate in tonal magnificence and clarity of sound. $449.95.
Check No
9 on
Circuits can do for the performance
of a hi-fi receiver, visit your local
Sansui Audio Dealer. He will let you
hear the difference.
Woodside, N.V. 11377
Electronic Distributors (Canada) British Columbia
Reader Service Card
from Readers
With reference to the article, "Stereo
Disc Cutting," in January 1968 AUDIO,
we were extremely disappointed that
although virtually every major stereo
disc cutting system manufactured of
any note was referenced, absolutely no
mentioned was made of the HAECO
(Holzer Audio Engrg. Co.) Stereo Cutter Model SC -1.
McIntosh Solid State
A Cutting Omission
Santa Monica, Calif.
The new McIntosh 36 page
. . . Grundy mentions three available cutterheads, omitting completely
the outstanding Haeco iron -vane head
built by Howard Holzer here on the
West Coast.
catalog gives you all the details on the new McIntosh
The Custom Fidelity Company
Pasadena, Calif.
solid state equipment.
addition, you'll receive absolutely free a complete up-todate FM Station Directory.
McIntosh Lab. Inc.
2 Chambers St., Dept. C 4
Binghamton, N. Y. 13903
The HAECO Stereo Cutter Model
SC -1 is indeed an admired and respected system, certainly deserving inclusion in the list of mastering -quality
cutters published last January. Mr.
Howard S. Holzer, President of Holzer
Audio Engineering Co., points out that
the HAECO Model SC -1 is now in use
by more than 40 companies.
Crosstalk Measurements
I was interested in David Hafler's
letter (February issue) concerning
crosstalk measurements. His point regarding termination of the unused
channel is a valid one; measurements
taken with one channel unterminated
can be completely misleading. I have
reviewed amplifiers for British journals
for some years and in my experience
crosstalk has to be measured from
channel A to channel B as well as B
to A to be accurate. It might be thought
that these figures would be identical;
not so. A high-level circuit on one channel can couple to a low-level circuit on
the other. Only in rare cases are the
layouts completely symmetrical.
New Milford, Conn.
The Electronic Crossover Crossup
The schematic and the parts list on
page 22 of your February issue have
errors in them. (Sorry about that-a
new and, we hope, completely correct
schematic is shown on page 74-Ed.)
A lot of people including me, do not
have an amplifier lying around
you were making the thing from
scratch, you probably would have made
the circuit boards bigger and included
a separate power supply. I am delighted that you published the article
as I have been a nut on the subject of
crossovers for years.
Right now I'm using R -C filters and
they work fine, furnishing 6 dB/octave
between midrange and tweeter, and 12
dB/octave between woofer and midrange. 12 and 18 would probably be better with horns.
Eldridge, Calif.
I was happy to see you have arrived
at the "Electronic Crossover." Welcome. I have been there for some time
via a tube circuit published by Crowhurst. The tubes are 12AU6's and suffer from high -impedance which called
for tremendous modifications before
the calculated values were obtainedcut and try, plus cathode followers.
Best of luck with your new amplifiers.
San Francisco, Calif.
On page 66, in reference to the
woofer section, it says "all that is
needed is a high-pass filter." This
should read "low-pass." The lead from
the emitter of Xl and R5 to R11 and
C15 is shown connected to the +28 V.
bus in error. Also the junction of R20
and R21 is shown connected to the
emitter of X6 rather than to its base.
Vancouver, B. C.
(Continued on page 74)
Check No. 10 on Reader Service Card
Check No.
on Reader Service Card
We designed a
new automatic
turntable for
men of hi-fi.
A his and her automatic turntable? Well, why not?
For him, the PE:2020 is a turntable that tracks
like a manual, acts like an automatic and works like
a charm. An exclusive little device in the cartridge
shell lets him dial the perfect trackinc for each record in the stack, at a precise 15° vertical styllus
tracking angle. What this all means is maximum
precision. Minimum distortion. And minimum record wear.
For her, the 'PE -2C20 is styled to fit beau=ifully
into any decor. But beyond' its form is its function.
The PE -2020 operates so simply for I -er. Thanks to
an exclusive command center. Just one handsome
lever is alt she :ouches to start, stop, repeat, c.1e,
pause and lift.
There's also an automatic anti -skating device.
An automatic scar ner. A four -speed setting control with pitch cortroll
and much more. The
PE -2020 only $129.35 less base.
Test and see the PE -2020 for yourself at your
local Elpa dealer. If you don't know who he is and
wish further information just ask us..
And when you visit him, be sure to bring her
along. There's something in the PE. 2020 for both
NEW HYDE PARK, N.Y.. 11040.
the Elpa PE -2020
Interlude-the Cashette
I'll hafta laugh, once again. This is
going to be an interim report, to my
considerable amusement, on the great
war between cartridges and the cassette. You may consider this as Act I,
Scene II, the Comic Relief-though
with serious undertones.
Well, how can I go very far into such
a battle without sampling the goods? I
got 'em all right-some of them. I've
had an 8 -track player on hand for
many a moon. And RCA, indefatigible,
never at a loss on the uptake, has positively flooded me with 8-track offerings,
for which I offer my regretful thanks.
Regretful because, as already mentioned, some kinds of music I just will
not play. (Now don't jump to conclusions! One of the first 8 -trackers I
singled out for playing was a Chet Atkins catridge. He's tops in the Country
Music field.) I have browsed over the
whole 8 -track spectrum, such as it is.
So-plenty of cartridges. Stacks of
them. All sorts. Even a few classics of
a safe and sane nature, guaranteed not
to clip anybody's ears. But cassettes?
Back last fall, Ampex sent out a
great wave of publicity concerning
their new lines of cassettes to come, via
the very extensive Ampex tie-ins with
leading record companies. Terrific
promise! I smacked my lips. Also, as a
sampler, they mailed out their very
first, a whole Great Classic in a single
cassette, complete. Scheherezade, by
Rimsky-Korsakoff! Some classic.
Now I like Scheherezade, after a
fashion. In fact, it was the very first
consciously classical music I ever
heard, at the age of maybe ten. My
sainted and revered uncle, Lee Wilson
Dodd, a man who I held in awe and
worshipped from afar, had a big, dignified Victrola in his living room, a place
where we kids were very seldom allowed. A wind-up, of course, for acoustic 78s-but this was back then. On
ultra -special occasions we were allowed
to hear that machine play a solemn
piece that ought to have been the B
Minor Mass of Bach or something, so
reverential was the hushed little listen12
ing audience gathered around the Vic.
It was always the same, "The Young
Prince and the Young Princess," from
that great mahstuhpiece, Scheherezade. Dee dah dah dah, diddle -diddle
dee dah dah dah-I can hear it yet.
(But keep in mind that his really was
one of the very earliest "classical"
records, not counting operatics. My
uncle was entirely right. That twelve inch all -instrumental acoustic 78 was a
work of art. The strains of Scheherezade, a classical symphony orchestra
for the first time in a living room, and
they sounded inexpressably noble to us,
coming out of the grand old furniture
piece with the adjustable doors and the
curved roof, and the picture of Nipper,
His Master's Dog, on the inside....)
Well, we live and learn, don't we?
And so now, XXX years later, I really
don't find Scheherezade very awesome,
even a la cassette. Just an old chestnut,
well roasted. (Roasted, incidentally, by
the famed Leopold Stokowski in this
cassette. He probably roasted the old
78 too, in his slightly younger days
forty -odd years ago. He's durable.)
To get back, I waited patiently all
last fall, expecting a batch of shiny new
cassettes full of delectable music to appear any minute in my mail box. None
did. And I kept forgetting to do something positive about it, like, say, phoning the producers and demanding the
things quick by messenger, please.
What is happening out there is CASSETTES. Perfectly good cassette player on hand, loaned to me by Ampex
itself, and still nothing to play on it
but Scheherezade.
My real thought, to tell the truth,
was slightly panic-button. Maybe I've
let this thing slide-maybe the market
is flooded with all sorts of cassettes
from everybody all over, and I've been
off daydreaming? So I went into emergency. By phone, right in N.Y.C.,
where (some of) the action is. First I
thought I'd better try Mercury -Philips.
After all, it was Philips (of Holland)
which developed the cassette. They
ought to know.
-Oh no sir, we don't have any of
those on hand here, and anyhow, we
aren't sending them out to reviewers.
Company policy.
But, I sputtered, I'm not a reviewer
least not right now. That is, well,
I am a reviewer but not when I write
about cassettes because then I am a
technical writer (well, what else could
I say?) andI'm sorry sir, we do not ship cassettes to-Hey, now look here, little
lady (or words to that effect), I am a
technical writer (gulp) for AUDIO. And
we are doing a, uh, study of cartridges
and cassettes and I LIKE cassettes and
so you really had betterIn that case, sir, she said, obviously
relieved, I will refer you to our office
in Chicago, where Mr. X is in charge
of cassettes.
Just to be sure, I wrote to Mr. X,
explaining what gave and asking for
some samples of their very best and latest pre-, I mean recorded cassettes, preferably not including Scheherezade.
Hopefully including some Bach. (Well,
I didin't actually say this, I only wishful -thought it.) What I wanted to see
was how the cassette could stack up, so
to speak, as a real, honest tape alternative to the best LP records. That, after
all, is a major point and, indeed, a very
important one for cassettes, if they are
to go beyond the immediate portable or
automotive field.
Then I decided to go all-out. No use
calling RCA. That would be like calling
Tokyo in 1941 to find out about U. S.
military competition. (I've just been
reading a book called Incredible Victory-but that's beside the point.) So,
tactfully, I by-passed RCA's phone and
called Columbia. Who else?
Hmmm. 765 4321. Columbia really
sewed that number up.
"CBS," she answers. "Columbia Records Reviewers Service?" I countered,
"May I ask in what connection?" she
came right back.
Well, was I flustered. Have you ever
tried to explain a cassette to a telephone operator? Er, c -c -cassettes, I
I will connect you with the cashier
NO, not the cashier! I yelled. Cashettes! Just give me Reviewers Sher vise, I mean Service. (That's the way I
am on the phone.) So the poor, inoffensive reel-to-reel operator, who obviously wasn't going to lay her hands on any
cashettes for a long time, plugged me
-Columbiarecords, Reviewerservice.
May I halp you?
(Now the following, to protect the
loyal employees of this branch of the
CBS Empire, is deliberately garbled
and merely like what was actually said,
by virtue of a strange coincidence. But,
so help me, it conveys a segment of the
truth, as of a couple of months before
you read this.)
... Reviewerservice? Uh, this is Edward Canby of AUDIO, and I'm writing
a piece on tape cassettes and cartridges.
I was wondering if you could send me
a few of your cassetteslike what did
Oh sir, I'm sorry
you say? I think you have the wrong
extension,-NO, NO! You are Reviewerservice, aren't you? Yes sir-. And
you handle both records and tape in
that office, don't you? Oh yes, she said
brightly. Tape! We do handle tape. I
can give you our latest tape releases-.
Uh, well, you see, I just wanted cas-
APRIL 1968
The photomicrograph above portrays an errant, hard -to track castanet sound in an otherwise conservatively modulated recording. The somewhat more heavily modulated
grooves shown below are an exhilarating combination of
flutes and maracas with a low frequency rhythm complement from a recording cut at sufficiently high velocity to
deliver precise and definitive intonation, full dynamic
range, and optimum signal-to-noise ratio. Neither situation is a rarity, far from it. They are the very essence of
today's highest fidelity recordings. But when played with
an ordinary "good" quality cartridge, the stylus invariably
loses contact with these demanding grooves-the casta-
nets sound raspy, while the flute and maracas sound
fuzzy, leaden, and "torn apart." Increasing tracking weight
to force the stylus to stay in the groove will literally shave
off the groove walls. Only the High Trackability V-15
Type II Super -Track® cartridge will consistently and effectively track all the grooves in today's recordings at record saving less -than -one -gram force
even with cymbals,
orchestral bells, and other difficult to track instruments. R
will preserve the fidelity and reduce distortion from all
your records, old and new. Not so surprisingly, every
independent expert and authority who tested the Super
Track agrees.
At $67.50, your best investment in upgrading your entire music system.
Send for
list of Difficult -to-Track records, and detailed Trackability story: Shure Brothers, Inc., 222 liartrey Ave., Evanston, Illinois 60204
Q 1967 Shure Brothers Inc.
Check No. 13 on Reader Service Card
APRIL 1968
tile turDtaflle a
... ani
sdio oeeøs
retout Uuraflìlìty, too!
settes. Sir, we only handle records and
tapes here, I'll transfer you-JUST A
MINIT, miss! (If she transferred me to
the cashier I was going to scream.) A
cassette is a kind of a tape, I said, and
it would go through your office,
wouldn't it? Oh yes sir, all the tape
releases go through us and we'd know
about it if-, Cassettes, I said, Do you
have any yet? (I added the yet, as a
sort of precaution.)
Just a minute sir, I'll ask
JACK, (voice off -phone). Like Cashette. Do we have anything like that?
The gemman says, Cashettes. Like do
we have any? (Mutter of male voice in
background.) Sir, no one around here
seems to have heard of anything like,
er, what did you say? Cashettes. CASSETTES, I said as gently as I could
shout. Well sir, I'm afraid we can't
help you.
If Columbia had any, miss, your
office would- Oh yes sir! All the releases go through our office. Would you
like our latest tape releases now? I can
get them for you in a jiffy. (I already
had them, on paper. 4 -track cartridges.
8-track cartridges. Period.)
Well, Columbia isn't-wasn't admitting to any cashettes. So I gathered. If
not Columbia, then who?
Ampex New York
Now, all this could be a lot of malarckey and boloney and I hoped that
this very cooperative CBS gal didn't
tell me a lie, not even knowing. She was
so sweet. Next, I phoned Ampex New
There's hardly an engineer in the broadcast field that hasn't used a
Rek-O-Kut turntable in his career. Rek-O-Kut has been building studio
turntables for over a quarter century. So you are assured of buying
top quality sound reproduction along with the ruggedness and durability that boradcast and commercial installations demand. The rim
drive Rek-O-Kut B -12H by Koss Electronics permits slip cueing without sacrificing fidelity. And your KosslRek-O-Kut will last and last
and last with a minimum of maintenance and repair. Write for complete
details on the popular Model B -12H or the 16" studio B -16H today.
SPEEDS: 33%, 45, 78 rpm. NOISE LEVEL:
59db below 5 cm/sec average
recorded level. MOTOR: custom-built computer type heavy-duty hysteresis
synchronous motor. 45 RPM HUB: instantaneously removable by hand.
PILOT LIGHT: neon light acts as an onloff" indicator. FINISH: grey and
aluminum. DECK DIMENSIONS: 14 x 15'1/46". Minimum
Dimensions: (for cabinet installation) 173/4" w.
x 16 " d. x .?" above deck x 6'%" below.
PRICE: B -12H Turntable $165. S-320
Tonearm $34.95. Optional BH Base
for audition room $18.95.
Rek -O- k;ut Turntables by
Koss Electron cs Inc
2227 N. 31st St., Milwaukee, Ms. 53208
Export Cable: STEREOFONE
Koss-Impetus/2 Via Berna/Lugano. Switzer'and
to show
Publicity did know all about cassettes.
Phew! (I almost said "cashettes" to the
Ampex gal-now where would that
have got me?)
However, there were none on hand in
the New York office. So she said she
would contact the main tape office in
the midwest area-by tieline, I figured
-and would have a selection of the
latest Ampex cassettes, not including
Scheherezade, on the way to me in no
time. In fact, she had it all set up when
she called me back within an hour or
so. Real cooperation.
As of right now, they are on their
I must end this bit of comicality with
a serious coda. Just because the cassette is well behind the tape cartridge
in terms of recorded
it does not follow that it is either unimportant or a loser. Far from it. There
was a time, for instance-remember?when the classical record stores were
briefly flooded with 45 rpm 7 -inch classical albums, well ahead of any noticeable volume of LPs from the same
companies. The LP came up strong
from behind, though, and the 45 retired
to you -know -where. Maybe the same
for the cassette, given awhile?
Check No. 14 on Reader Service Card
APRIL 1968
The advantages of
buying the Pioneer SX-700T
am -fm stereo receiver
start her
The guiding principle of all Pioneer stereo receivers is
meticulous craftsmanship and value. The devotion to perfection
literally begins at the power plug and extends to the
priceless performance delivered to the speakers.
Sensitive and selective, the new SX-700T has been built to
perform brilliantly in either suburban or metropolitan areas,
easily pulls in distant weak stations even when adjacent
to strong local signals
at a price only slightly above the
"budget" receivers. $249.50 less walnut cabinet.
With its versatile controls, the SX-700T becomes the center of any
impressive stereo system for phono, tape, or broadcast.
At Pioneer, continuing research and design
pioneer every new development of sound
COMPARE THESE SPECS: 60 watts music power (8
ohms); Distortion: less than 1.0% at rated output;
FM sensitivity (IHF): 2.2 uv; Signal-to-noise ratio:
60 dB; Frequency response: + 1 dB from 25 to
50,000 Hz; FM hum and noise: -75 dB; Channel
separation: 35 dB (at 1,000 Hz); Full controls, such
as simultaneous tape-record, tape monitor, headphone jack, etc.
never end!
Value All -Ways!
Franchised Pioneer dealers will be
happy to demonstrate the SX-700T and
other Pioneer components to you. For
more details and literature on the complete line, please write: R. Von Sacken,
140 Smith St., Farmingdale, N.Y. 11735.
Check No. 15 on Reader Service Card
APRIL 1968
FM Rock
Many FM stations are swinging to "serious
rock" and other hip music (Bob Dylan, underground chatter, W. C. Fields, Japanese Koto
music, Indian ragas, and other offerings of this
ilk) , according to a recent issue of Newsweek
One FM station executive advised that monthly
billings shot up tenfold when this move was made.
Another observed that AM rock-and-roll stations
failed to "get with" the new music, noting that
their audience has grown out of the Monkees .. .
looking for music with greater depth.
We're pleased that FM is continuing to prove
itself as an aggressive medium that recognizes
broadcast needs that escape AM programmers. At
the same time we're fearful that the Rock move-
The Industry Mourns
The high fidelity component industry
was saddened recently by the loss of three
executives who contributed to its growth
over the years: Julian Gorski, 54; Edwin
C. Cornfield, 56; and Sidney Frey, 47.
Mr. Gorski, who was President of
United Audio (Dual automatic turntables) came to the United States in 1938,
a victim of Nazi persecution. In later years,
he received Austria's highest civilian
award, The Gold Medal of Austria, for his
charitable work. An accomplished musician, he found himself attracted to the
fledgling high-fidelity industry, introducing Dual changers and Wigo speakers to
this country. As a graduate engineer, he
was able to develop, with the Dual factory,
a line of automatic turntables that earned
the respect of audio buffs. He leaves this
ment might overpower the FM airwaves, converting FM to a mass medium from a class medium.
An 18 -minute Guthrie folk tune is simply not palatable to most adults. Nor is good sound reproduction necessary to enjoy this form of entertainment.
We wonder if Newsweek's report covered an isolated boomlet in hip music or the beginning of a
trend. Letters from readers concerning the content of local FM station programming would be
most welcome.
P.S. FM station revenues in 1966 displayed an
increase of 31 per cent over the previous year.
Convention Panel Discussion
The Audio Engineering Society Convention in
Hollywood, Calif., April 29 -May 2, has a promising
panel discussion scheduled: "Audio Quality and
Its Deterioration: Electronic and Subjective."
Moderated by Keith O. Johnson, Gauss Electro physics, Inc., with panelists Allen E. Byers,
United Recording Electronics Industries; John
M. Eargle, RCA Victor Record Div.; John T.
Mullin, 3M Company; and Carl S. Nelson, Capitol
Records, the panel discussion will attempt to explain how types of electrically measurable distortion cause subjective sound changes or deterioration. Catch this one if you can. It should be
especially interesting.
heritage, as well as the memory of him
as a sensitive, generous person.
Edwin C. Cornfield, one-time executive
secretary of the Institute of High Fidelity,
and sales executive for a number of firms
in the high-fidelity industry, numbered
audio and music as his main interests. The
large, genial man played a major role in
organizing and running the Institute's hi-fi
shows during his tenure in office, attracting and introducing many people to good quality sound. He will be missed by industry members, many of whom became good
Sidney Frey produced the first stereo
records as president of Audio Fidelity,
Inc., propelling the industry into stereophonic sound. His "Dukes of Dixieland"
and "The Brave Bulls" records, among
others, were mainstays of audio enthusiasts about a decade ago. The pioneer's
verve in the field of recording will not soon
be duplicated.
APRIL 1968
The X factor in the new Pickering XV-15.
The X in the new Pickering XV -15 stands for the
numerical solution for correct "Engineered Application." We call it the Dynamic Coupling Factor
DCF is an index of maximum stylus performance
when a cartridge is related to a particular type of
playback equipment. This resultant number is derived from a Dimensional Analysis of all the parameters involved.
For an ordinary record changer, the DCF is 100.
For a transcription quality tonearm the DCF is 400.
Like other complex engineering problems, such as
APRIL 1968
the egg, the end result can be presented quite simply.
So can the superior performance of the XV -15 series.
Its linear response assures 100% music power at all
Lab measurements aside, this means all your favorite records, not just test records, will sound much
cleaner and more open than ever before.
All five DCF-rated XV-15 models include the patented V -Guard stylus assembly and the Dustamatic
For free literature, write to Pickering & Co., Plainview, L.I., N.Y.
Dynamic Coupling Factor and DCF are service marks of Pickering
Check No. 17 on Reader Service Card
proud that Sherwood FM tuners were
selected because of their low distortion by
America's foremost heart -transplant pioneers
to receive telemetered EKG data in their critical research programs.
We are
Hirsch-Houck Laboratories evaluates the 0.15%
distortion Sherwood tuner shown above as
follows: "The tuner has a usable sensitivity of
1.8 microvolts, with an ultimate distortion
level of -48 db. This is just about as low as
we have ever measured on an FM tuner,
The S-3300 features our unique SynchroPhase FM Limiter and Detector with microcircuitry, field-effect transistors, a stereo
noise filter (which does not affect frequency
response), and of course, only 0.15% distortion at 100% modulation. Less case- $197.50
Electronic World, Oct., 1967
Amplifiers and speaker systems
best suited for low -distortion tuners!
Sherwood offers three low -distortion amplifiers precisely suited for your needs-led by
the Model S -9000a with 160 watts music
power (at 8 ohms). The 140-watt S -9900a and
the 80-watt S -9500b feature main and/or remote stereo speaker switching and separate
terminals for monophonic center channel or
extension speakers. All feature 0.1% distortion at normal listening levels. Prices from
$189.50 to $309.50.
Our acoustic -suspension loudspeaker systems
were designed to reproduce music with minimum distortion and coloration. You can hear
the difference low distortion makes. Hear
Sherwood's low -distortion Tanglewood, Ra
vinia, Berkshire, and Newport at your dealerthen take a pair home for a no -obligation
triaL Prices from $84.50 to $219.50.
4300 North California Avenue, Chicago, Illinois 60618
Write dept. A-4
Check No. 18 on Reader Service Card
APRIL 1968
The Truth About
Stereo Amplifier Power Ratings!
and FRED
Why music power ratings of solid-state amplifiers can
be false! Component hi-fi vs. packaged equipment
power -output ratings.
power amplifiers may share identical
power output ratings, but, in truth,
they may have widely different
power capabilities.
The Institute of High Fidelity and
the Electronic Industries Association have attempted to standardize
power -output ratings and methods of
measurement of power output. Thus,
one might assume that a common
reference for comparison and a solid
definition of the capability of power
amplifiers now exists. In practice,
however, the converse is true in ratings designed to indicate amplifier
transient power output capabilities,
such as the IHF dynamic output rating (IHF-A-201) and the EIA music
power output rating (EIA RS-234 Al
The reason for the discrepancy
lies in the fact that both standards
allow the manufacturer to rate and
measure the power output capabilities using a regulated power supply.
Unlike the power supply furnished
with the amplifier, the regulated
power supply can deliver all the current the amplifier requires, and the
supply voltage does not change.
Further, there is no ripple on the
regulated supply to add distortion to
the output waveform near the clipping level, or to add hum to the input signal.
The EIA standard is primarily
used by packaged equipment manufacturers. These are the manufacDIFFERENT MANUFACTURERS'
*RCA Electronic Components and Devices, Somerville, N. J.
APRIL 1968
turers of portable phonographs,
packaged stereo hi-fi consoles and
packaged home entertainment consoles. The EIA music power output
is defined as the power obtained at
5 per cent total harmonic distortion
or less, measured after the "sudden
application of a signal during a time
interval so short that supply voltages
have not changed from their no signal values." The supply voltages
are bypassed voltages. These definitions mean that the internal supply
may be replaced with a regulated
supply equal in voltage to the no signal voltage of the internal supply.
For a stereo amplifier, the music
power rating is the sum of both
channels, or twice the single channel rating.
The IHF provides two methods to
measure dynamic output. One is the
constant supply method. This assumes that under music conditions
the amplifier supply voltages undergo only insignificant changes. Unlike
the EIA method, this measurement
is made at a reference distortion.
The foregoing method is used by
most high fidelity component manufacturers. The reference distortion
chosen is normally less than one per
cent-considerably lower than the 5
per cent EIA value used by packaged equipment manufacturers.
A second method prescribed is
called the "transient distortion" test.
This requires a low -distortion modulator with a prescribed output rise
time and other equipment, all in a
rather complex setup. The modulator output is required to have a rise
time of 10 to 20 milli -seconds to
simulate the envelope rise time of
music and speech. This measurement is done using the internal supply of the amplifier and, consequently, includes distortion caused by
voltage decay, power supply transients, and ripple. This tends to be
more realistic and to give lower
power-output ratings than the constant supply method. Actually, both
IHF methods are supposed to be
used, with the lowest power rating
obtained at reference distortion with
both channels operating, both in and
out of phase, to be used as the power
rating. (There is some question concerning unanimity among high fidelity manufacturers on actually performing both IHF tests.)
Since music is not a continuous
sine wave, and has average power
levels much below peak power levels,
one might conclude that the music
power or dynamic power ratings are
true indications of a power amplifier's ability to reproduce music program material. The problem is that
all three methods described here
have a common flaw. Even the transient distortion method fails to account for the amplifier's ability to
reproduce power peaks while it is
already delivering some average
power. In the "real world," the amplifier is almost never sitting at zero
output when it is called on to deliver
a transient. For every transient that
comes along after an extremely quiet
passage or zero signal, there are hundreds that come along on top of some
low but non -zero average power level.
magnitude of the
constant slope
between these two
points= effective
series resistance
no -signal current
clipping- level
1-Regulation curve for capacitive rectifier power supply.
2-Typical power supply regulation
This can best be clarified by examining the power supply. Many
amplifiers have regulated supplies
for the front-end or low-level stages,
but almost none provides a regulated
supply for the power output stages.
This is so because regulation requires extra transistors or other devices; it becomes costly, especially
at high power levels. The power supply, then, for the output stages of
power amplifiers, is commonly a
non-regulated rectifier supply having a capacitive input filter. The output voltage of these supplies is a
function of the output current and,
consequently, of the power output of
the amplifier.
Power supply regulation
ó 40
Ñ 30
no -signal
Fig. 3-Equivalent circuit for single -ended
capactive input rectifier supply.
Fig. 4-Equivalent circuit for split capaci-
tor -input rectifier supply.
Power supply regulation is dependent on the amount of effective
internal series resistance present.
The effective series resistance includes such things as the d.c. resistance of the transformer windings,
the amount and type of iron used in
the transformer, the amount of surge
resistance present, the resistance of
the rectifiers, and the amount of filtering. The internal series resistance
causes the supply voltage to drop as
current is drawn from the supply.
Figure 1 shows a typical regulation curve for a rectifier power supply that has a capacitive input filter.
The voltage is a linear function of
the average supply current over most
of the useful range of the supply.
However, notice that a rapid change
in slope occurs in the regions of both
very small and very large currents.
In class B amplifiers, the no -signal
supply current normally occurs beyond the low current knee, and the
current required for the amplifier at
the clipping level occurs before the
high current knee. The slope between these points is nearly linear
and may be used as an approximation of the equivalent series resistance of the supply.
The amount of power lost depends
on the quality of the power supply
used in the amplifier. Accordingly,
rating an amplifier's power output
with a superb external power supply
(that is, not using the amplifier's
own built-in power supply) gives
false music power outputs. You can
be sure that under actual usage it is
Figures 3 and 4 show equivalent
circuits for capacitive -input rectifier
supplies. In these circuits, Idc is the
average supply current, Rs is the
effective equivalent series resistance
of the power supply, E. is the no signal voltage, and Ea is the steadystate supply voltage. The steadystate voltage, E,, is related to the
no -signal voltage, Ea, as follows:
Es =
- R. Idc
Equation 1 shows that the supply
is equal to the no-signal
supply voltage, Ec, only when there
is no current other than the no signal current being drawn from
the supply. As soon as the amplifier
begins to deliver some power to the
load, the power supply is called
upon to deliver some current. A
single -ended power supply delivers
current on alternate half cycles, and
each half of a split supply delivers
current on alternate half cycles.
Therefore, in each case the supply
current, Idc, is related to the peak
output current, as follows:
Id. =
The power output is related to the
peak output current, as follows:
where RL is the speaker load resis-
This is explained for those who
are mathematically -inclined in the
boxed area. For readers who would
rather not go into details, simply
skip this section. But take our word
for it that it proves that an amplifier
with a 31.5 watts/channel music
power rating could well be, in fact,
28.7 watts/channel, without selecting an exaggerated example.
This 10 per cent decrease in
measured transient capability may
go up to 20 per cent in some casps.
One such case is where the no -signal
load is less than that shown in Fig 1.
The no -signal load includes the
class AB bias current of the output stages and all of the current
drawn by the preceding stages and
their associated bias networks. This
may well be below the 250 mA
shown, pushing the no-signal voltage
up into the steep portion of the regulation curve. This would cause a
(Continued on page 22)
APRIL 1968
tance. Consequently, the supply
current is related to the power
output by:
(2 P. O.\
r2 RL
Combining equations
In relating average current and
power output, it is assumed that
sine-wave signals are included and
that no parasitic losses exist.
This can be simplified by assuming RL to be 8 ohms and by letting
W2 = 10. Equation 5 then becomes:
E. = Ea
0.158 R. (P. O.)
To illustrate the inability of the
no-signal supply voltage to indicate
the transient power capability of an
amplifier, assume that an amplifier
power supply has the regulation
characteristics shown in Fig. 2. Using the values for voltage and current from Fig. 2, the music power
rating, based on the no-signal voltage (44.8) and an 8 -ohm load, is:
31.5 watts/channel
8 RL =
(63 stereo Music Power watts)
assuming no parasitic losses.
(The factor, 8, in equation (7) is
derived in converting peak-to-peak
volts to rms volts.)
The effective series resistance, according to Fig. 2, is approximately
6 ohms. If the amplifier is delivering
tor is equal to half the difference
between the supply power delivered
(P,) and the power dissipated in the
load (P. 0.), as follows:
PT = (P, - P. O.)/2
Ipk2 RL
Ink E.
and 4
P. O.\
- R. (27,2RL)
E. = E.
an average power of 2 watts per
channel, or a total of 4 watts, the
supply voltage drops from 44.8, according to equation 6:
E. = 44.8
0.158 (6) (2) = 42.9
8 RL
= 28.7
decrease over the actual transient
power capability.
To examine the effect of R. on
transistor power dissipation, assume
a typical complementary-symmetry
circuit, such as shown in Fig. 5.
Assume a regulated supply under
no -signal conditions; the capacitor,
"C", is charged to a voltage equal
to E,/2 at the clipping level. The
maximum peak load current, Ipk
(max), is given by:
(max) can be expressed as follows:
PT (max)
P. O. (max)
Equation (14) indicates that maxi-
mum transistor dissipation is approximately 20 per cent of full
power output. At the point of
maximum dissipation, the power
output is given by:
Because the supply delivers current
on alternate half -cycles, the average
supply current, Ida, is given by
= Ipk/7r
2r2 RL (15)
The ratio of the power output at
maximum dissipation P. O. (max
diss.) to maximum power output
P. O. (max) is then given by
P. O. (max disc.)
P. O. (max)
The power (P,) delivered by the
supply can then be expressed as
P. O. (max diss.)
P, _ (Ipk E,)/Tr
The power delivered to the load,
P. 0., is given by
P. O. = (Ipk2 RL)/2
The dissipation, PT, for each transis-
5-Typical complementary -symmetry circuits.
and solved for the peak load current (Ipk) at maximum average
transistor dissipation, the following
expression is obtained:
Ipk = E,/(A RL)
When this value is substituted in
equation (12), the ratio of maximum
average transistor dissipation, PT
(max), to power delivered to the
load at full power output P. O.
If equation (12) is differentiated
(or 57.4 stereo Music Power watts)
The percentage change is
X 100, a 10 per cent
Ipk (max) =
Fig. 6-Power output and dissipation
functions of
and RI..
Power output a
maximum transint
transistor dissi
APRIL 1968
greater decline in supply voltage
when the amplifier was called on to
deliver 2 watts or so of average
It should be emphasized that,
while there is a discrepancy between
the actual power available and the
power measured under the EIA
Music Power Method or the IHF
Dynamic Power Methods, these
methods are not without merit. The
IHF Dynamic Power Rating, in
conjunction with the Continuous
Power Rating, produces an excellent indication of how the amplifier
will perform. The EIA Music Power
Rating, since it is measured at 5 per
cent THD with a regulated power
supply, provides less than an adequate indication of amplifier performance because there is no indication of how the amplifier power supply voltage reacts to power output.
There are some important factors
that are considered by packaged
equipment manufacturers, the primary users of the EIA Music Power
Rating. These considerations are
mostly economic in nature and affect
many aspects of the amplifier performance. Since there is no continuous power output rating required,
two amplifiers may receive the same
EIA Music Power Rating but have
vastly different continuous power
ratings. The ratio of music power to
continuous power is, of course, a
function of the regulation and effective series resistance of the supply.
One reason for the vast difference
in ratings used by the console or
packaged equipment manufacturer,
compared to ratings used by the hifi component manufacturer, is that
the latter does not always enjoy the
luxury of knowing just what will be
required of his amplifier. The console manufacturer always designs his
amplifier as part of a system, and
consequently knows the speaker impedances and just how much power
will be required to drive them to produce an adequate sound output. The
console manufacturer may use high efficiency speakers requiring only a
fraction of the power needed to drive
How to be your own Critic of
the New Synthesized Music
kind of new music pioneered by the
musique concrète (music generated
from concrete and other objects)
group of Frenchmen, now championed by Stockhausen and other
contemporary Germans, are fumbling to find a name for this music
that will be both accurate and meaningful. The name "electronic music"
is accurate to the extent that this
kind of music is generally "performed" by electronic tone generators and tape recorders. Composition
is often done with the use of computers. The name is not precise,
however, because natural sounds are
also used; speeded up, slowed down,
etc. Thus, "synthesized" music
would be a more appropriate name
than "electronic" music, since non-
electronic sounds are often combined
with electronic-generated sounds.
Composers are having their own
problems about this. They communicate their messages awkardly
with titles like "Poeme for orchestra
and tape recorder" or "Concerto
grosso electronique." The title offers
a clue of what is to come, and knowing this much is better than nothing
in your approach to a completely
unfamiliar contemporary composer.
"Electronic music" is really an
imprecise term, as noted earlier.
"Synthesized music" and "synthesized sound" seem to be the best
available so far. You should make
precise use of both of these titles,
since they should not be considered
You are listening to "synthesized
many component-type acoustic-sus tic suspension systems. The difference may be such that the console
may produce the same sound pressure level with an amplifier having
one -tenth of the power output. High
ratios of music -power to continuous power capability are common in
these consoles. A typical ratio of
IHF music power to continuous
power may be 1.2 to 1 in component
amplifiers, whereas a typical ratio of
EIA music power to continuous
power in a console system may be
2 to 1. Console manufacturers take
advantage of the EIA music power
rating with resultant economic advantages, resulting from the reduced
regulation requirement of the power
supply. A high ratio of music power
to continuous power means higher
effective series resistance in the
power supply. This, in turn, means
less continuous dissipation on the
output transistors, smaller heat
sinks, and a lower-cost power supply.
(More to come in future articles.)
music" when the piece seems to qualify in some way as in an art form.
Does it seem to hold together? Does
it seem to have form-or purpose`
or meaning? Does it stimulate
thought-about itself or about something else? Is there anything about
it that you would be likely to remember? These are very loose criteria of
music as an art form, but they are
enough to justify the name "synthesized music."
You are listening to "synthesized
sound" when not one of the above
messages gets through to you. For
instance, you may experience the
same reaction from an "electronic"
piece that you do from Dupont's
sample card of Lucite color chipsahead of the decision on what color
to paint your garage. This is synthesized sound, a random sampling of
the existing tone colors and, hopefully, the discovery of a few new
ones. From these tone colors, music
can be composed, but you are not
hearing anything yet that classifies
as composition. Many composers of
synthesized music go through this
preliminary stage of experimentation. The composer you are evaluating may be very inexperienced at his
job, or he may never progress with
APRIL 1968
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APRIL 1968
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his abstract tone colors beyond the
status of technician. This is your decision to make, and it will help you
toward the decision if you know how
long he has been experimenting.
The discovery of synthesized
sound should be credited to some
nameless experimenter of years ago
who first noted the effect of a running -down spring -powered phonograph-and then wondered what
would be the new sound at consistantly higher or lower speed than
standard. And what about reverse
play? With the advent of the tape
recorder, all such experimenting became easy. Synthesized sound was
first offered to mass America in the
mid -1950s by Jim Fassett as an intermission diversion on the New
York Philharmonic broadcasts. Interest was enough to justify the release of Columbia MI4938, a collection of Jim's experiments under the
title "Strange To Your Ears."
Obviously, the technique has
broadened with the passage of time.
Anything goes now, just so long as it
is mechanico-electronic manipulation of the original sound as accepted
by the microphone. The electronic
organ has contributed effects, especially in the controlled degeneration
of tone which is available in its "percussion" stops. The guitar amplifier
offers adjustable reverberation, vibrato and other "distortion." Composers with soldering irons design
band-pass filters and gating circuits.
Other composers with access to computers put in tired old sounds and
take out fresh new ones.
The oldest synthesized music to
have survived its test on people dates
from 1949. The actual creation was
musique concrète (Ducretet-Thomson 20001), and its composers were
Pierre Schaeffer, Pierre Henry and
Michel Philippot. Some of concrete
is synthesized sound, admittedly experimental abstractions, but some of
it is true music in the philosophical
definition of the term. Pierre Henry's Veil of Orpheus includes electronically-distorted voices from
"Hell" that will stand your hair on
The ground rules
You no doubt have heard the new
medium, but probably have never
attempted to get orderly and objec24
tive in your thinking about it. Synthesized sound (?) music (?) can be
very frustrating because there is
rarely anything comfortable to use
as a launching pad for your analysis.
If the work is titled and presented to
you in a music environment like the
concert hall or your hi-fi system, let's
assume that the intent is synthesized
music rather than abstraction in
This music isn't Popular, or Classical, or Baroque, or Romantic, or
identified by any other of the familiar labels. Like any critic in a
medium foreign to familiar traditions, you must fumble at the start.
And good fumbling material can always be found in the non-artistic
limitations within which the composer proposes to do his creating.
Here are some of the ground rules
which may govern this game. You
will probably discover others, and
certainly you should be looking for
1. Before being changed electronically, were the source sounds in this
piece made by traditional musical
instruments and/or the human
voice? The composer may choose to
limit himself by this tie with the
past. Here again you are to use your
best possible judgment. You may be
deceived; some of the distortions are
extremely difficult to identify with
the original.
Are all of the sounds the new kind,
or is this a combination of the new
and the old? Do you occasionally
hear something familiar, maybe out
of Chopin? This decision is easy, and
it is another kind of limitation within
which the composer may be holding
2. If the piece is exclusively electronic, are you taking it as a selfcontained package from a tape or a
disc? Or might there be performers
on stage with microphones and amplifiers? If it is the self-contained
package, it is strictly for the ears;
opportunity for concomitant visual
entertainment does not exist. Most
synthesized music falls in this category at present, and the absence of
the visual (or at least the imagination of what the visual might be) is
a rather serious handicap to the total
entertainment value of the offering.
Just as the Hollywood or TV personality must make an occasional
guest tour or do an occasional Broad-
way show, today's composer of electronic synthesis must make an occasional concert hall appearance to
prove that his music is still manmade, not the product of machine
For instance, there is a recent
composition by Milton Babbitt for
"live soprano, recorded soprano and
recorded instruments." The live and
the recorded sopranos are the same
girl, but in her live incarnation she
provides the element of visual entertainment, justifies a concert-hall
presentation, and proves that music
is still a human offering. (This total
effort can never, of course, be recorded without complete loss of its
purpose. It would then be just another work for two recorded sopranos.)
3. If the work proposes to combine
live music and synthesized music in
concert performance, how compatible are its two elements? Otto Luening and Vladimir Ussachevsky composed Rhapsodic Variations for tape
recorder and orchestra. Who is master of this and who is slave?
4. Does the recorder dominate and
dehumanize the performance? Must
the conductor, usually the final word
on tempi and taste, relinquish his
traditional authority? In combinations of the live and the synthesized,
this is another decision of yours, and
you should credit the composer with
especially inspired creation when
the conductor seems to come out on
So much for the ground rules.
Here are some telltale signs to watch
for. The presence of all or any of
them may suggest that you are listening to synthesized music.
Does this piece seem to have
form? You need not know the traditional music forms. For instance, the
form of a good novel; exposition, development, climax, conclusion. Or
even the form of a good prize-fightwith a slow start and a fast ending.
Does it have rhythm, something
predictably repetitive like a good
old-fashioned "beat" to hold it together? Melody, in the popular definition of the word, is almost sure to
be wanting from electronically distorted sources of sound. A good beat,
though, will tend to hold the composition within the category of music.
Does it arouse an emotion like
APRIL 1968
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APRIL 1968
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humor, fear, intense pleasure or displeasure? Or any other emotion?
Does it hold your interest-perhaps by starting a chain of thought
about something seemingly unrelated? This is not to be confused with
Does it seem to have "rememberability"? Do you feel that you
would recognize it if you heard it
Any evidences of the above are in
its favor, and probably remembrance
is the most important. It is not necessary that you like the piece. You
may dislike it intensely, in which
case it will have succeeded in its
probable purpose and qualify as
music. Beware, though, if it bores
you. Here you are justified in calling
it synthesized sound.
Synthesized music is an immature
art, and it is still difficult for the
critic to identify a composer by a
taped or disked hearing of his newest
work. Every composer aspires to this
kind of identification. Relatively few
realize it, even in traditional music.
Except perhaps for Gershwin, Wagner, Richard Strauss, Prokofieff and
Stravinsky, the trained musicologist
will often guess wrong on a short segment of an unrecognized work.
The lazy way for a composer of
synthesized music to attain original Fig. 1-Robert A. Moog stands in front of
his company's electronic music composi-
tion -performance equipment.
property-and to withhold credit
from the first composer that you hear
use them.
The human voice, distorted or
otherwise, has been used by most of
the synthesists. It is an extremely
effective and dramatic sound, especially after a long episode of "instrumentalism," which tends to get
monotonous because of the unfamiliarity of all of the instrumental
Fragmentation and silence is a
clue to the combined output of a particular group of composers. If the
unfamiliar composition is explosive
and fragmented, and if this is interspersed with long periods of silence
which are an integral part of the
music rather than conventional
pauses between sections or pieces,
you're probably right if you attribute
this music to one of a group of farout young Americans, mostly disciples of Webern. These composers
have been writing this way for undistorted voices and instruments, and it
is logical that their recent creations
in the medium of synthesis will show
the same symptoms.
Acceptance in the older medium
is a clue to be explored by research
rather than by listening, and for this
one you must first know the composer's name. Do you find this name
in the Schwann Catalog or on concert programs as a composer of nonelectronic music? If so, you have a
hint of the kind of background experience that includes exposure to
the good and bad of music that has
gone before. It not, your composer
may have come up by way of the
slide rule and the soldering iron.
This clue must never be the sole
basis of your judgment, but if you
are confused in making a decision
between music and sound, it is fair
to use the clue in weighing this decision.
ity is by the creation of new sounds.
The manner of creating them is frequently guarded as trade secret.
Sometimes, as previously mentioned, he becomes preoccupied with
the trade and forgets the art aspects
of the end product.
Some of these new sounds and new
techniques are already in the public
domain. Here are a few clues to help
you to recognize them as common
The French School produced
musique concrète, but since that
auspicious start, the output of the
French School has not attained the
international reputation of the Germans and the Americans. The
French influence in music is too
subtle to be apparent to the amateur
critic, though the pro can identify a
French orchestra, a French conductor or a French composer with reasonable ease. One clue is the saucy
competence of French percussion,
and percussion in general is a kind of
natural bridge between the traditional and the synthesized.
The German School is another
matter. Here there are two very conspicuous clues. One is great length.
The other is rules; rules to compose
by and rules to listen by. Mahler
wrote two-hour symphonies. Wagner
wrote five -hour operas and voluminous prose about how you should
listen to these operas.
Too often, the great length is out
of step with the listening habits of
the 1960s, and it may also seem
somewhat conceited for any composer to assume that he operates at
the level of genius that will justify
this much listening.
Karlheinz Stockhausen is the
most widely heard of the contemporary Germans. Already some of his
compositions in synthesized music
crowding an hour of performance
time, and he is working on another
that is to last an entire evening. Still
another, Stockhausen's non-synthesized Zyklus of 1955, is circular in
form; its single performer starts anywhere around the circle and quits
when he gets back to his starting
point. This piece confounds the
whole evolution of music since the
days of the Fifteenth Century German academicians; today you find
the likes of it only in the continuous -loop tape cartridges.
The name of Pierre Boulez, the
"Great White Father" of the musique concrète group, should be
added to the very few names previously mentioned. Other names could
easily be dropped, but this would be
unfair to names overlooked who may
already have contributed something
that will endure in the literature of
music. If you are to be the critic,
your responsibility is to everyone
who has something sincere to say in
this new art form.
There's a lot more to the art of
synthesized music today than meets
the ear. Timbres and rhythm patterns are beyond the scope of conventional musical instruments and
human capabilities. Just as teenagers have their "way out music,
serious music listeners now have
their radically different musical
form in synthesized music. And as
evidence of its growth, Schwann's
Catalogs added 11 new "electronic"
music listings last year.
APRIL 1968
Marantz components are too good for most people.
Are you one of the exceptions?
For the most astonishing set of specifications
you've ever read, write "Exceptions," Marantz, Inc., P.O. Box 99, Sun Valley, California 91352
15 solid-state
The Marantz components illustrated, top to bottom: SLT-12 Straight -Line Tracking Playback System Model
Model 1OB Stereo FM Tuner
Model 7T solid-state Stereo Pre -amplifier Console
120 -watt Stereo Power Amplifier
Check No. 27 on Reader Service Card
APRIL 1968
FROM THE VERY beginning of
"classical" recording, collectors of
discs have recognized one of the
prime advantages of the recorded
medium, virtually never previously
possible in history
the direct,
"AB" comparison of two or more different performances. It is in truth a
miraculous kind of a situation and
we would marvel every day if we
weren't so utterly used to it.
Alas, the mass sale of LP records,
sight unheard, has made things far
more difficult than they were in the
old 78 days, when every record store
had a couple of air -tight listening
booths in which, so long as you could
sustain life without oxygen, you were
privileged to make all the comparisons you wished, straight out of
stock. Can't tell you how many hours
I stifled away in that fashion as a
college student, ploughing through
huge piles of heavyweights, staggering home blue in the face with maybe
a half -dozen winnowed out for pur-
Now, it is the record critic who decides in advance, or you after the
fact. You buy your two versions and
go home to find out which you like
best. No wonder there are crowds at
the discount houses.
To take a splendid instance, perhaps you will have read my review
[in this issue] of a superb new recording of well-known Rossini overtures (Everest 3186, with the Orchestra of the Accademia di Santa
Cecilia under Fernando Previtali),
the finest I had ever hoped to hear.
Well, just after I had written that,
I caught up with another simultaneous release, same month, on the
RCA Victrola label. Rossini overtures! Only one disc, to Everest's
two, but some of the very same
music. Better still, both conductors
are pure-bred Italian, and right in
the tradition. Two minutes of listening will tell you this, even if you
don't know both names; but you will
know the second conductor, all
right. Arturo Toscanini.
Which is best? Ha ha, I'm not going to say. Because my point is that
the AB comparison itself is so marvelously revealing, in the over-all
and in detail. Frankly, I was quite
astonished at what came out for the
ear in this comparison, but I leave
this astonishment for you to discover for yourself, at your pleasure.
I will only note a few attendant
circumstances, for which you must
make some allowance, and which do,
indeed, affect the total score or rating which you may want to apply to
each recording.
Toscanini's NBC disc is, of course,
of many years ago and a broadcast
at that (I think), with all the problems of age in the technology and no
"re -takes" for editing. But these are
relatively late recordings, and the
sound is remarkably good; Carnegie
Hall provides the acoustics, rather
than the sterile Studio 8H. So you
will not have trouble on this score,
though the modern stereo on Everest
is a superior sound.
The Everest orchestra is virtually
unknown hereabouts, and the more
remarkable is its performance, as per
my review. But it is, note well,
Italian-and in Italy. Toscanini,
Italian to his own core, conducts an
American orchestra-which means
an American-based outfit with members from just about everywhere you
can imagine as to background and
origin, yet amalgamated in the
School of New York City. I, for one,
could hear a distinct difference between these two orchestras, that is
surely in part due to this difference
in musical background.
So get out your fat wallet and whiz
down to the record mart. Everest
3186, containing two discs. RCA
Victrola VIC 1274, one disc. See
what you think. You may be surprised.
P.S. Ho ho. Turn around once and
there's another one!
Rossini Overtures-and now it's
still another Italian conductor, a first
rate man; this time we have a crack
British orchestra in a recent -vintage
reissue in stereo. Carlo Maria Giulini with the Philharmonic Orchestra, Seraphim S 60058. Make it an
ABC comparison? Cheap at the
(Of course if you really want to be
exhaustive, and exhausted, you'll
first want to look for a new alphabet.
to the nth.
Even before the above recordings
appeared there were over thirty
records of Rossini overtures listed in
How to Build Your Own
Sheet -Metal Reverberator
OF ALL THE SOUND effects available to the experimenter none is
more exciting and versatile than reverberation. It has many uses in
commercial sound studios and no
popular-music recording studio can
afford to be without at least one reverberation device.
The generous application of reverberation is the major technique
used to produce the BIG sound of
many radio stations. On the other
hand, reverberation also has at least
one serious application in the field
of synthesized or electronic music.
The property of reverberation is
most effective here if it is much bigger than life. That is to say, if it has
greater echo times, longer decay
times and much greater intensity
than the reverberation obtainable in
conventional rooms or auditoriums.
This is true because the electronic
music composer seeks effects that do
not occur in conventional music or
normal acoustical situations. Such
Check No. 29 on Reader Service Card
When Stanton engineers get together, they draw the line.
The frequency response curve of the new Stanton 681 erence to approve test pressings. They must hear exactly
Calibration Standard is virtually a straight line from what has been cut into the grooves. No more. No less.
But you don't have to be a professional to hear the
10-20,000 Hz.
difference a Stanton 681 Calibration Standard will make,
That's a guarantee.
In addition, channel separation must be 35 dB or especially with the "Longhair" brush which provides the
greater at 1,000 Hz. Output must be 0.8 my/cm/sec mini- clean grooves so essential for clear reproduction. The improvement in performance is immediately audible, even
If a 681 doesn't match these specifications when first to the unpracticed ear.
The 681 is completely new, from its slim -line configtested, it's meticulously adjusted until it does.
Each 681 includes hand -entered specifications that uration to the incredibly low -mass moving sysverify that your 681 matches the original laboratory stand- tem. The 681A with conical stylus is $55.00, the
681EE with elliptical stylus, $60.00.
ard in every respect.
For free literature, write to Stanton MagNothing Iess would meet the needs of the professional
studio engineers who use Stanton cartridges as their ref- netics, inc., Plainview, L. I., N. Y.
Lumber: seven boards, 2"x4"x3'; two
boards, 2"x4"x6'; one board 2"x4"x
11/2'. Total: 341/2 running feet.
2. Metal: one sheet of No. 26 spring
steel; 5'10"x2'6". One-half in. holes
drilled two in from both ends with
centers at 2'/2" 5", 5", 5", 5", 5" (see
12. Loudspeaker motor: may be speaker
Fig. 1-Construction plans of the sheet-
metal reverberator. The finished unit
should be fastened to the floor or walls
of a small room or closet which can be
acoustically treated to prevent unwanted
sound from escaping.
2-Block diagram of recommended
hookup. Note: two channels and reverberators are required for sterec
with cone and basket removed.
13. Driver amplifier: five to twenty watts.
14. Equalizers: for driver amplifier to pro-
vide selectivity of reverb. frequency,
A. Rubber grommets may be made
from pieces of inner tube, tape, etc., if
not available.
B. The loudspeaker motor is easiest
to obtain by removing the cone and
basket from a complete loudspeaker.
The cone must be cut away while preserving the spider intact with the voice
coil. Some brands of speakers bolt the
basket to the magnet, making disassembly easier.
C. The cartridge is to be mounted at
right angles to the steel. A stiff wire
is inserted in the stylus shank and
soldered to the plate.
3. Glue: one bottle "Eimers" glue (large
4. Nails: fifty 21/2" nails; fifty 1'/2" nails.
5. Insulation: 30' fiberglass insulation.
6. Wire: 30' rubber -covered twin con-
ductor; 30' single conductor, shielded
Tape: Plastic, insul., one roll No. 33
Scotch or equiv.
8. Plugs: 4 male, 4 female phone plugs.
9. Plugs: two male, 110v wall plugs.
10. Ceramic phono cartridge: or equiva-
lent, must be modified.
for ceramic phono cartridge.
11. Preamp
3-Two views of the completed sheet metal reverberator. The white area on the
right of the above photo is fiberglass
which is glued to the closet door for
sound proofing. A five -watt transistorized
unit is used to drive the loudspeaker
exaggerated effects are the tools of
surrealistic music and are, in some
ways, similar to the paintings of Dali
and other surrealistic painters.
To the experimenter who wishes
to experiment with reverberation in
an amateur sound studio situation,
two techniques usually are available.
These are tape recorder reverberation and the spring reverberation
made famous by the Hammond or30
gan company. A third, less common,
technique is to use a coiled tube with
a transducer at each end. Of the
three, the coiled spring is probably
capable of the most natural reverberation. The tape recorder reverberator has a major drawback: The
quality of the sound produced by the
tape reverberator is too precise, non resonant and uncolored for some
purposes. While this is useful, it
leaves the field open for a mechanical, resonant reverberator with a
strong signal and a long delay time
(longer and stronger than the spring
reverberator). Such a reverberation
device is the large sheet -metal reverberator which has found great
acceptance in the professional re -
cording and broadcasting field under
the name EMT-140. [Gotham Audio
Corporation, New York City, has
distributed more than 800 such units
in this country and there is as yet no
other device of this kind available.
The EMT-140, incidentally, is protected by U. S. Patent No. 2,923,369
and is made of specially controlled
steel not available generally. It costs
just under $3000. It must be pointed
out, therefore, that the similar device
which this article describes is not in
the performance class with the
EMT-140 and may not be manufactured in violation of the above patent.]
The sheet metal reverberation device described here was actually
built by the author for the electronic
music laboratory at North Texas
State University. In use for about
two years, it has proved to be capable of a variety of strong reverberation effects and is more subtle than
the tape recorder reverberator.
The accompanying drawing, Fig.
illustrates the construction as it
was carried out, with the exception
that the corner supports for the sheet
of steel were eliminated, reducing
the damping effect caused by six
rods and rubber grommets. The reverberation device was mounted in
APRIL 1968
Z=4'26 guage sheet steel 5;10"x2;6",
mounted on rubber grommets on
top and bottom.
X=loudspeaker motor
Wider shelf of 2X4;
can be made for
larger speaker
36' S'
j'122 -4 Top view
a closet that was acoustically treated
with fibreglass to prevent sound
leakage (the reverberator does emit
some sound) .
The sheet is simply a sheet of
stainless steel purchased at a metal
and roofing dealer (for about six
dollars) . The gauge of the steel is
No. 26, although other thicknesses
would probably work as well so long
as the sheet is stiff enough to support itself without sagging or bending under its own weight.
The pickup employed in this instance was the ceramic type of contact microphone commonly sold for
attachment to electric guitars. In this
type of device, the mounting bracket
is isolated from the case and attached to the ceramic element so
that sound is transmitted through
the bracket into the pickup. The
quality of the sound picked up can
be improved if the case is mounted
securely to the frame without putting undue pressure on the element.
Although not everyone wants a
wide frequency response from a reverberator, this one could be improved in the high end by using a
pickup with less mass in the coupling
between the steel -sheet diaphragm
and the ceramic element. Certain
types of phonograph cartridges with
removable styli could be used here
simply by replacing the stylus with
a piece of wire and soldering the
other end to the steel diaphragm.
APRIL 1968
tape rec.
Side view
Front view
A critical part of the design is the
modified loudspeaker motor. It is
possible to use any speaker here, although some types are better than
others. Ideally, one should have a
10- or 12 -in. speaker with a fairly
large magnet (six to sixteen ounces)
and a bolt -on basket assembly. The
speaker employed by the writer was
a TV replacement type, 12-in. in
diameter, with a rivited basket.
Thus, it took considerable patience
and care to remove the speaker basket from the magnet assombly; however, it can be done.
If the spider is attached to the
magnet assembly, as most are, no
problems arise here. If the spider
should happen to be attached to the
basket, it would have to be moved to
a new location. The builder would,
therefore, be wise to avoid the latter
type of speaker.
Before removing the basket assembly, cut the cone down to where
about 2 -in. of paper is left from the
apex to rim. This small cone area can
be glued directly to the sheet -metal
diaphragm after the speaker motor is
bolted to the support structure in the
center of the steel sheet. Be careful
to have the motor properly positioned before glueing.
Concerning the method of driving
the reverberator and feeding the output into the sound system, several
things may be said. In the first place,
feedback from the output to the in -
Microphone mixer
put must be rigorously avoided (unlike the tape recorder reverberator)
as the system will howl just the same
as a sound system in an auditorium
might. It is necessary to take the output from a sound system before an
amplifier stage and to mix the reverberation signal back in after the
stage in order to provide isolation.
Signal ground loops must be carefully avoided, as these can cause
enough feedback to force the system
to oscillate. Remember, several watts
of audio are driving the sheet and
only a few milliwatts are needed
from the pickup. Figure 2 shows a
block diagram for driving and mixing.
To sum up, the reverberator is
capable of a very large, long reverberation effect of a sort not usually
obtainable from more common reverberators. Small recording studio
operators should find it to be an attractive device for generating bigger
sounds, and electronic music experimenters may want to build one for
the subtle sound it offers and for an
effect greater than that from commercially available devices (excepting a very costly European -built unit
which uses principles similar to the
unit discussed here) In spite of the
attractiveness of the device (from an
application viewpoint) it can be
built for under fifty dollars. All you
need is a place large enough to accommodate it.
ABZ's of FM
noise -free,
high fidelity characteristics of FM
transmission, we shall now devote some
time to a study of how an FM signal is
created electronically and how it is
radiated for ultimate reception by an
FM receiver.
There are two general methods used
for the generation of an FM signal. The
first is sometimes called "direct FM."
This involves varying the frequency of
the main oscillator of the transmitter
in accordance with the modulation to
be impressed. In the second method,
frequency modulation is achieved by
varying the phase of a signal obtained
from a stable, crystal oscillator.
Direct FM
The most obvious and direct way to
obtain a frequency-modulated wave is
through variation of one of the frequency-determining elements of an ordinary, high -frequency oscillator. A
crude method of doing this is illustrated in Fig. 1. Here, a "condenser"
microphone is connected in parallel
with the frequency-determining L and
C of a familiar Hartley oscillator. As
long as no sound is fed to the microFig.
2-Reactance tube appears
phone, the resonant frequency will be
determined by the sum of the capacitances of the microphone and C in
parallel with the coil, L. This frequency represents the resting, or carrier frequency, translated to FM
terminology. As sound waves hit the
microphone capacitor plate, it vibrates
closer to, and further away from the
fixed plate. Thus, its capacitance (and
hence the total capacitante in the circuit) is altered. The instantaneous frequency is therefore caused to shift
above and below the central resting frequency, and a frequency -modulated
signal is developed.
1-Simple, direct
FM, produced by
in oscillator
(L, C, and Cl)
total capacitance
"tank" circuit
"Condenser" microphone
In actual practice, a reactance tube
(or transistor) acts as a variable inductance (L) or capacitance (C) across a
predetermined resonant circuit, as
shown in Fig. 2. Audio information applied to the grid of V1 effectively
changes the apparent "L" of the output
circuit which, in turn, varies the oscillator frequency. In practice, the oscillator frequency is kept at around 5
MHz, and the reactance modulator is
able to shift that frequency by only
about ± 5 kHz. Frequency multiplers,
such as doublers and triplers, are then
used to boost the center frequency up
to the 88-108 MHz band required for
FM broadcasting. In so doing, the mod -
variable capacitive reactance across the master oscillator tank circuit (L, C).
ulation swing is correspondingly increased. As an example, if the 5 MHz
basic oscillator frequency is multiplied
by 18 (say, by doubling once, and
tripling twice), the resulting frequency
will be 90 MHz. Since the modulation
(or change of frequency) undergoes the
same multiplying factor, a total modulation of 4 kHz x 18, or 72 kHz, will
result; just about right for the usual
maximum of ±75 kHz required in
standard FM broadcasting. A block
diagram of a transmitter using the reactance tube approach is shown in Fig.
Since the basic oscillator used in reactance modulation transmitters is not
crystal controlled (a crystal -controlled
oscillator could not be "forced" to shift
frequency, since the crystal determines
the resonant point), if no further steps
were taken to stabilize the transmitter,
its frequency might be expected to drift
considerably. The FCC requires that
center frequency be maintained within
±2 kHz. In the example cited, this
would represent a stability of approximately ±111 Hz at the 5 MHz master
oscillator level. To insure such extreme
stability, a crystal oscillator is used as
a reference to produce a correcting
voltage (very much like the familiar
AFC voltage used in receivers to help
keep stations tuned in), as shown in
Fig. 4.
When a carrier wave shifts back and
forth in phase while maintaining a constant frequency, this shifting causes the
same effect as if the frequency itself
were being instantaneously varied.
This variation represents a moderate
amount of frequency modulation and is
the basis of all phase -modulation
schemes for producing an FM signal.
The indirect FM produced will depend
3-Block diagram of FM transmitter
using "direct" FM approach
Check No. 33 on Reader Service Card
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This offer expires June 15, 1968 and
is applicable only on the UHER 4000
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gCopyright 1968
Uher by Martel
Martel Electronics Inc. Sole U.S. Importers
2339 South Cotner Avenue, Los Angeles,
California 90064; New York: 1199 Broadway
Chicago: 5445 No. Lincoln
upon the maximum angle that the carrier wave is shifted, and on the frequency at which the shift takes place.
In one variation of the phase -modulation approach, the maximum practical phase angle that can be produced in
the phase modulator is 30 deg. (approximately half a radian). Since the
FM produced equals the product of
modulating frequency and phase angle,
for a 15 kHz modulating frequency, we
could expect the resulting FM to be 15
kHz x 0.5 (radians), or ±7.5 kHz. Offhand, you might expect that, starting
with a 10 MHz crystal -controlled oscillator (the chief advantage of all the
Phase Modulation approaches is that a
crystal -controlled oscillator can be used
as the master oscillator), one would
only have to multiply the frequency 10
times to come up with a 100 MHz carrier frequency and a ±75 kHz modulation capacity.
Examination of the mathematical relationships just stated discloses that
this would only be true for a 15 kHz
modulating tone. At 50 Hz (the lower
end of the audio spectrum desired in
FM transmission) we would get FM
amounting to only 50 Hz x 0.5 (radians) = 25 Hz! In phase modulation,
therefore, something must be done so
that regardless of modulating fregeticy,
the net amount of FM will be the same,
notwithstanding the audio modulating
frequency. An R -C corrective network,
such as shown in Fig. 6), must be interposed between the audio source and the
phase modulator, so that the higher frequencies will be attenuated relative to
multiplier s
(5 MHz)
Correcting voltage
Fig. 4-Accuracy of master oscillator frequency is maintained
reference which provides
5-Starting with
by a crystal -controlled
corrective voltage.
200 kHz ±25 Hz signal, using a second crystal oscillator makes
a 90 MHz ±72.9 kHz FM signal.
practical the generation of
200 kHz
400 kHz
1200 kHz
3600 kHz
± 50 Hz
-1150 Hz
± 450 Hz
10.8 MHz
± 1.35 kHz
the lowest audio modulating frequency
(in this case, 50 Hz). Therefore, all
audio frequencies concerned will produce only a mimimal 25 Hz of indirect
FM when the phase angle is 0.5 radians.
If we divide 75,000 Hz (the desired
total deviation at carrier frequency) by
25 Hz, it becomes apparent that doublers and triplers would have to be arranged to multiply the starting frequency by some 3000 times. Put another way, if we wished to have a
carrier frequency of 90 MHz, we would
have to start with a crystal master
oscillator having a frequency of 90,000,000/3000, or 30,000 Hz. While crystals of such low resonant frequency
can be made, a more practical approach
is to use a crystal having a freqeuncy
of around 200 kHz. After several doublers and triplers, we achieve a frequency of 32.4 MHz, as shown in Fig. 5. At
this point, a second crystal oscillator
output, at 27.4 MHz, is heterodyned
with the 32.4 -MHz signal to produce a
5 -MHz output. This signal is then
tripled and doubled in much the same
way as was shown in Fig. 3, resulting in
a final output of 90 MHz having a maximum deviation of ±72.9 kHz, as required.
Several variations of phase modulation have been developed over the
years, many of which are in current
use in practical transmitter installations. One, known as the Armstrong
system, simplifies the method used to
obtain substantial phase modulation.
Another, known as a Serrasoid Modulator, secures a relatively large amount
of initial phase modulation, reducing
the amount of frequency multiplication
required to achieve a carrier frequency
at the assigned FM frequency.
Transmitter power & range
The Federal Communications Commission has set up rules governing assignment of FM frequencies, maximum
permitted radiated power, frequency
separation between stations and allowable signal interference ratios. The
various classes of station in service are
shown here.
90 MHz
72.9 kHz
27.4 MHz
Class of
Class of
Power (kW)
I -A
I -B
certain cases)
32.4 MHz
±4.05 kHz
15 MHz
45 MHz
±12.15 kHz
±36.45 kHz
50 (to 100 in
0.5-1 (night) to
Power will be determined by elevation of antenna, since the higher the
elevation of antenna, the greater the
coverage or range of transmission and
reception. Bear in mind that since FM
(Continued on page 75)
Check No. 35 on Reader Service Card
This suggestion is made only to those who
have top-flight integrated amplifiers with an
electrically separate preamp and power amplifier, or individual preamp and power amplifier components. It involves your present
equipment and three Sony components: the
TA -4300 electronic crossover and two TA3120 stereo power amplifiers. It's for those
venturesome enough to break away from
conventional approaches to sound reproduction. If we've described you, then these
Sony components can bring you just that
one iota closer to realism in home music.
Here's why.
The electronic crossover goes between the
preamplifier and the power -amplifier portions of your present stereo amplifier. It
divides the audio -frequency spectrum into
three ranges, and sends each range to a
separate amplifier: your existing power amplifier, plus the two Sony TA-3120's. Each
amplifier feeds a speaker expressly designed to handle that particular part of the
audio spectrum. By not forcing a single am-
plifier to handle the full range of frequencies, IM distortion is reduced. By eliminating the inductor -capacitor-resistor crossover networks built into ordinary speaker
systems, speaker damping is not distrubed.
The speakers' motions are always fully controlled by the amplifiers. Speaker impedance
variations have less effect on the amplifiers.
Also, you can select crossover frequencies
to suit the speakers of your choice, or experi-
ment to discover the audible effects of vary
ing crossover points. The points provided
are 150, 250, 400 or 600 Hz between woofer
and mid -range, and 3, 4, 5, or 6.5 kHz between mid -range and tweeter. A bass turnover control fits the system's response to
the characteristics of the woofer, and a bass boost control lets you experiment with extending the woofer's bass response.
The Sony TA -4300 solid-state electronic
crossover costs $199.50; the two TA -3120
solid-state amplifiers $249.50 each. Sound
extravagant? Maybe just a bit. But so are
the results. Interested? Write for literature
on how to upgrade your system. Sony Corporation of America, 47-47 Van Dam St.,
Long Island City, N.Y. 11101.
Get drunk with power
& Decor
Vertical -Style Hi-Fi Installations
Joseph Malta, Bayonne, N. J. Compactness and chair -side control
mark this stereo hi-fi setup. Equipment, from top to bottom, includes a McIntosh MR71 stereo FM tuner, McIntosh MA5100 con-
trol amplifier, "Rondine" Rek-O-Kut manual turntable with an
Ortofon cartridge, and Kos Pro -4 and Pro -4a stereo headphones.
To the left of the equipment is a control box which controls a
high-intensity lamp's illumination. Beneath the control is a switch
for the turntable, a second switch for a third -channel amplifier and
two additional headphone jacks. To the left of the tuner is a master
switch that shuts off the complete system. At the opposite end of
the room (not shown) are two Empire "Royal Grenadier" speaker
O'Conner, San Rafael, Calif. The cabinet housing stereo
equipment here was designed by the owner to take up a minimum
of floor space (it's located in a den that has limited wall space).
Made of walnut, stained in fruitwood tones to match other furniture and to blend handsomely with ribbon mahogany walls, it was
constructed as two separate units. The base portion serves as storage space for magnetic tapes and records. The top unit contains
all the stereo hi-fi components: A Scott FM stereo receiver and an
Ampex tape deck are concealed by a single tambour door that
slides up and down; a Miracord 10H automatic turntable is
mounted on a sliding drawer which can also be concealed by
tambour doors. A fluorescent lamp at the top of the section throws
light on the tape deck and, aided by the recessed and slanted front,
also lights the receiver and the turntable (when the latter is extended).
The top section of the cabinet creates a shadow-box effect. It is
indirectly lighted, and the antique gold -leaf back of this part produces a nice decorative effect. The uppermost portion also contains a single Jensen speaker system with its own volume control;
this is connected to the center channel of the receiver. A speaker
switch at the side of the receiver controls a pair of AR speaker
systems in the living room, a pair of Electro -Voice "Wolverine"
speaker systems in a family room, and a University outdoor
speaker in the patio area (the outdoor speaker also operates from
the receiver's center channel).
The AR amplifier delivers 60 watts per channel continuous
output at less than 0.5°/o harmonic distortion, 20 to 20,000
Hz, both channels operating simultaneously into 4 ohms;
50 watts per channel into 8 ohms.
One of the most important specifications of an amplifier is its power output. In
view of this, consumersmight expect this measurement to be presented clearly
and accurately in amplifier advertising. This has not been the case. In recent
years, a variety of vague or irrelevant terms has been used by manufacturers to
describe power output: music power, solid-state power, stereo power, audio
power, transient power, transistor power, IHF power and others. The list includes
terms invented by manufacturers and applied to their products alone, as well
as standards of measurement known only to advertising copy writers.
Acoustic Research uses the definition of a watt given in physics texts: work done
at the rate of 0.7375 ft.-lb./second. We know of no "transient watt" or "music
watt" which science recognizes. AR amplifiers are rated exactly as we
measure them, with both channels continuously delivering at least the rated
power without exceeding our harmonic distortion limit of 0.5°/o, or the I.M.
distortion limit of 0.25°/o. The laws of physics and the nature of music require that
power measurements, if they are to be meaningful, be made with a steady, uninterrupted tone, similar to the purest sound of a pipe organ. AR amplifiers
must deliver their rated power at all frequencies to which the ear responds,
not just at 1,000 Hz, where most amplifiers can deliver much more power than at
the extremes of the range of hearing. Distortion measurements are made through
the AR amplifier's phonograph input because music must go through the
amplifier this way-even though performance might be better without the
preamplifier in the circuit.
It is for these reasons that the power output rating of the AR amplifier is true for
any kind of musical tone, not just those easy for an amplifier to reproduce.
The AR amplifier is covered by a guarantee unmatched in the industry. If an
AR amplifier fails to operate as advertised within 2 years of its purchase date,
AR provides parts, labor, freight to and from the factory or nearest authorized
service station, and a carton if necessary-all with no charge for factory defects.
ACOUSTIC RESEARCH, INC., 24 Thorndike St., Cambridge, Mass. 02141
Check No. 37 on Reader Service Card
APRIL 1968
20 Years Old
Evolution of amplifying devices from vacuum tubes to transistors to integrated circuits.
WAS HARDLY more than twenty
years ago when Bell Lab Scientists
showed that a small piece of the element germanium could be made to
amplify a speech signal about forty
times. Shock waves of this revolutionary discovery are felt up to the
present day, with variations on the
Laboratory notebook entry recording discovery of the transistor effect at Bell
Telephone Laboratories.
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solid-state theme taking place constantly.
Transistors brought smaller equipment size, less heat production,
instant "on," lower power requirements, longer component life, near permanent operating characteristics
(compared to tubes) and, in many
instances, improved performance to
hi-fi equipment. With the advent of
stereo, which requires two of practically everything in amplifier and
tape electronics, and the addition of
multiplex circuitry for FM, transistors arrived on the scene just in
the nick of time.
How it works
Current flowing across the layer like structure of a transistor can be
controlled by an electrical signal applied to one of the layers. The flow
of electricity between these layers
can be changed. Changes in conductivity are produced by temporary
changes in the way electrons are distributed among the atoms in the
transistor layers.
To turn pure semiconductor materials [that is, material in between
good conductors of electricity
(metal) and poor conductors (rubber) ] into transistors, scientists add
very small amounts of the right kind
of "impurities." Some of these impurities are atoms of material that
interact with silicon or germanium
crystal lattices in such a way that
electrons (negative charges) detach
themselves and become free to move.
Other impurity atoms create deficiences of electrons, or "holes."
These holes are, in effect, positive
charges. The holes, as well as the
electrons, are able to move through
the material.
When the semiconductor crystals
are grown, they are purposely
"doped" with minute amounts of impurities. After the crystals are sliced
into wafers they are further altered
locally by precise processes to produce sandwiches of materials that
contain alternating layers with
either free electrons or free holes.
Where the two types of material
meet-at each junction-the loose
electrons and holes face each other.
Being of opposite electric charge
they are attracted to each other and
a few drift across the junction. The
impurity atoms have charges of their
own and these charges are fixed in
position in a solid. The net result
is that an electric field is formed
which prevents the motion of additional free electrons and holes.
Each three -layered sandwich becomes a transistor when an electrical
contact is attached to each of the
layers. The current flowing between
two of the contacts can be controlled
by applying an electrical signal to
the third. The signal in this way can
be amplified-made 50 to 40,000
times more powerful. Further, this
large current keeps step with the incoming signal so that the outgoing
signal is an enlarged image of the
original signal.
Outgrowths of the development of
transistors abound, of course. Junction and MOS Field -Effect Transistors (which, unlike conventional
transistors described above, are unipolar rather than bipolar devices)
have been developed. Integrated circuits which include transistors have
replaced discrete transistors in many
areas. But it all started only 20 years
ago by a trio of scientists who were
awarded the Nobel Prize for their
discovery in 1956.
Check No. 39 on Reader Service Card
Miracord gave
its great new
the light touch
There are Iwo new Elac/Miracord autcmatic turntables:
the 620 and 630, both born of the same aristocratic
lineage that bred the magnificent 501-i. But they ccst less.
Naturall', they don't offer everything- the 50H does.
But they do share many of its deiuxe chsrscteristcs::ts
gentle way with records; its exclush.e light -touch pushbutton controls; its cueing faciLties; its effective anti skate compensation; its simple s3lectio- of manna: vs.
automatic play; its ability to track wit) cart2idges designed for low stylus force operation; i13 low wow and
flutter and rumble content and. of course. its smcoth.
quiet performance.
Each operates at the 4 stancard
speeds, each has a powerful four -pole
induction motor, dynamically balanced tonearm with calibrated st3.1usforce dial, continuously adjustable
anti-skate compensation and cueing.
Both, like the 50H, play singe
records, manually or automaticaly,
either once -through -and -stop, or
repeating Lntil instructed to stop
Dr they can play stacks of up to 10 records, in automatic
3eque1ce_ Even without the famous 50H hysteresis
motor, you'll love evdrything else about the 620 or 630.
The E30 has a lathe -turned, dynamically balanced turnable. cast from non-ferrous metal. It has the Miracord
e}clueive leadscrew adjustment and indicator which lets
¡au adjust stylus over hang precisely.
The 620 has a pressure -formed non-ferrous turntable,
balanced for minimum wow and rumble. Like the 50H
and 630, its stylus force can be set from 0 to 7 grams to
accommodate any cartridge.
We think you will be happy with any
Miracord tLrntable. They're all pretty
amazing! And as for prices, the 630 is
$119.50; the 620, $89.50, both less
base and cartridge.
Visit your high fidelity dealer today;
or write: Benjamin Electronic Sound
Corp., Farmingdale, N.Y. 11735.
the light touch
wffere tIfe new RE15
was born!
typical boom or stand operating position) the area of greatest cancellation is
oriented directly at the sources of unwanted sound-the audience and the
sound reinforcement speakers.
E -V Reliability
ABC-TV also demanded plenty of
output. They got it. A crisp -55db. And
they got the reliability and ruggedness
typical of all E -V professional dynamic
microphones, as well. Famous E -V
Acoustalloy b diaphragm plus multiple
dust and magnetic filters assured unchanging response and sensitivity. Plus
a "bass tilt" switch to cure boomy
acoustical problems.
The slotted "backbone" of the REI5
identifies it as the latest in the Electro Voice series of Variable-D® and Continuously Variable-D® microphones.
It's very possibly the most
significant achievement
of them all. Write for
your copy of
The biggest names in show
business play the Hollywood
Palace on ABC-TV. They demand the
finest sound possible. And they get it
from the new Electro -Voice RE15. It's
no accident, and here's why: ABC-TV
sound engineers worked with us for
almost two years perfecting the RE 15.
Their demands reflected the problems
that make TV variety programs one of
the toughest assignments for any sound
Small in Size
They asked for a small, light microphone. The REI5 is shorter than a pencil,
with a body no thicker than a Cannon
XL connector. And it weighs just 8
ounces. Perfect for a fast-moving boom
or for hand-held applications.
Flat Off -Axis Response
ABC engineers requested the same
response curve off axis as on axis. With
a big band in the same studio, some band
pickup from the back of the solo microphone would be inevitable. It wasn't
easy to make this "off mike" pickup as
smooth, flat and wide range as the on axis response, but that's exactly what
the RE15 has to offer at every angle.
The REIS is down only 3 db at 80° off
axis (in any plane) and just 8 db at 90°.
But at 120° and 180° the level drops over
19 db, and at 150° the RE15 response is
almost 26 db below the on -axis level.
This super-cardioid pattern (with a small
lobe at the back, 15 db down) proved
much more useful than a classic cardioid.
With the microphone tipped 30° (a
Super-Cardioid Pattern
But the next request almost stumped
us. They asked for wide front pickup,
so that a boom operator could easily
"work" two or more performers, yet
they wanted the RE15 dead at the rear
for longer "reach". In short, a polar
pattern similar to a ball sliced neatly in
half! And that's almost what they got.
Microphone Facts that giv
all the details. And, for an
impressive demonstration of RE1
capability, find a TV set with really
good audio, and tune to the Hollywood
Palace on ABC-TV, any Saturday night.
Or match the RE l5 with your own list of
demands. We think you'll agree that a
star was born on the Hollywood Palace!
FREE! Any E -V professional microphone will
be repaired without cost if it fails in the first
two years-regardless of cause. That's right,
repairs are free for the first two years ... no
questions asked!
to R.: Robert Craw-ford. Chief Uility: Eric Reid, Chief Boom
Operator; Euoene L.Jke-v:ski, Di', cicr; John Neal. Audio
Engineer, for ABC's Hclly+wood Fia ace.
Cecil Street, Buchanan, Michigan 49107
high fidelity speakers aid systems tuners, amplifiers, receivers public address loudspeakers
microphones phonograph needles and cartridges organs space and defense electronics
the voltage required to drive this signal current into the input, the output
of the amplifier is directly related to
input current.
If the amplifier uses an FET
(Field Effect Transistor) for input,
we have a device like a tube, and
voltage is the important parameter
about input. Now let's look at outputs.
If the output tube is a triode, probably transformer coupled, the most
meaningful way to view the output is
as a voltage source, with an internal
resistance that is lower than the design value of load impedance.
If the output tube is a pentode, or
a transistor, the most meaningful
way to view the output is as a current
source, with an admittance that is
lower than the design load, regarded
as admittance rather than impedance (which would be higher than
the design load).
In some circumstances it may be
more convenient to view transistor or
pentode outputs as voltage sources,
with source resistances higher than
design load values, but usually they
behave more like current sources.
The distinction between output circuits is no black and white one, definitely a function of either voltage or
current, as it is with input circuits,
where one or the other definitely
controls the signal amplified.
An ultra-linear circuit, regarded
as entity-the tubes with the output
transformer that provides the screen
taps, all acting as an ideal unit-is
part -way between these extremes. It
may be regarded as either a voltage
source with a source impedance ap-
More About
was examined in block diagram
form, where the amplifier and the
feedback are both boxes, functionally connected by lines. But what is
an amplifier, and what is fed back?
Is it voltage or current? To both of
these questions there are two answers. Let's illustrate.
The amplifier
If the amplifier uses a tube input,
the voltage signal applied to the
grid controls ultimate output. Varying the impedance in the input circuit will vary the current associated
with this input voltage, but the voltage is the important quality that directly controls the ultimate output.
If the amplifier uses a grounded
emitter transistor input, current is
the important quantity. Although
adjustment of circuit values can vary
Fig. 1. Schematic representation of the two basic kinds of input and output encountered
in amplifiers. Top left: voltage input, such as tube or FET; bottom left: current input, such
as grounded emitter transistor; top right: voltage output, such as triode tube; bottom
right: current output, such
transistor or pentode tube.
proximately equal to design load, or
as a current source with a source admittance approximately equal to the
design load.
Figure 1 shows the variety of amplifier ins and outs, before feedback
is applied. But from here on, we'll
not complicate the issue with inbetweens, but assume either voltage
or current inputs and outputs. On
the overall picture then, we have two
kinds of input and two kinds of output, according to whether the important parameter is voltage or current
at each end.
So in all we have four basic kinds
of amplifier (Fig. 2). Where both input and output are either voltage or
current, the amplifier may be regarded as a voltage or current amplifier. It merely amplifies the same
Where input is one and output is
the other, we have a transadmittance
or a transimpedance amplifier. In
effect, with one the amplifier increases the current delivered to the
load by a given input voltage, while
in the other the amplifier increases
the voltage developed across the output load by a given input current.
The feedback
Now with four possible kinds of
amplifier, each of which uses an input and an output impedance possessing both voltage and current
parameters, we can apply the feedback in a variety of ways.
At the output end, to derive a signal to feed back, we can use either
voltage or current. The feedback
signal can be made proportional to
either the voltage or the current output (Fig. 3) .
When the feedback signal gets
back to the input, it can be injected
in series or in shunt with the external
input (Fig. 4) This is sometimes referred to as voltage or current combination at the input. Series injection combines voltages; shunt injection combines currents.
Now put the whole thing together,
and we have four kinds of amplifier,
to each of which four kinds of feedback can be applied. Thus there are
16 basic, simple kinds of feedback
(Fig. 5) before we get into combinations using multiple feedback, or
cases where the output isn't simply
voltage or current dependent, but
Voltage source
Current source
Current input
APRIL 1968
KENWOOD's 2 -Year
Warranty oll Both
Parts and Labor
..proof of the sound
approach to quality
Superior skills and advanced technology give KENWOOD an edge in quality
control that pays off in years of dependable listening pleasure for you
Performance reports from dealers all over the country reflect the reliability they
have come to accept as characteristically KENWOOD. You can put your confidence in KENWOOD ... we do ... and we back it up in writing.
Visit your nearest KENWOOD franchised dealer and ask him for a demonstration of five outstanding receivers, multi -channel stereo amplifier and the new
KA -2000, 40 watt stereo amplifier. Compare the value of KENWOOD with much
higher -priced receivers on the .market, and
join the audiophiles everywhere who are
choosing KENWOOD for ...
TK -40 Solid State AM/FM Stereo Receiver $189.95
the sound approach
3700 South Broadway Place, Los Angeles, Calif. 90007
69-41 Calamus Avenue, Woodside, New York 11377
Exclusive Canadian Distributo
- Perfect Mfg.
& Supplies Corp.
Check No. 43 on Reader Service Card
APRIL 1968
distortion, with certain limitations.
5. It stabilizes gain, reducing the
amount by which gain fluctuates due
to various causes.
four basic amplifier configurations, using different combinations
of input and output from Fig. 1.
Fig. 2. The
Each feedback loop changes all
these properties by the same factor.
For example, 20 dB feedback, voltage -derived from the output and
shunt injected at the input, will reduce gain by 20 dB, divide both the
input and output impedance by 10,
reduce distortion to one tenth, and
stabilize gain so that a fluctuation of
1 dB without feedback will be reduced to 0.1 dB with it.
Or if the same feedback is series
injected at the input, the input impedance will be multiplied by 10, the
other effects remaining the same.
The reader can have fun figuring the
various angles on simple feedback
Fig. 3. Different derivations for feedback, shown here in the same circuit.
Volts in
Voltage amplifier
Volts out
Fig. 4.
Different ways of injecting the
feedback at the input end.
somewhere between the two, or some
of the other things the theory overlooks.
Reasons for feedback
Current in
Current amplifier
Current out
What do we apply all these kinds
of feedback for? A variety of reasons,
but let's answer the question first by
what feedback does:
It changes gain. Negative
back reduces gain.
It changes input impedance. Acit is applied, it
cording to the way
Volts in
Current out
What impedances?
Now we start running into unexpected complications. When I referred to input and output impedance changes, I was deliberately
vague concerning the impedances
meant. For example, when we speak
of modifying output impedance, do
either increase or reduce input
impedance. Negative feedback using
shunt injection reduces input imcan
pedance, while using series injection
increases it.
3. It changes output impedance.
Negative feedback using current derived feedback increases output
impedance, while using voltage -derived feedback reduces it.
4. It reduces internally generated
Current in ( Transimpedance
Volts Out (
Fig. 2.
we mean the source impedance seen
by the load connected? Feedback
Combining the possibilities of amplifiers and feedback networks, we have 16 overall possible combinations, shown here. The letters under input and output in each have
the following significance: G indicates that feedback is not materially affected by the
value of external impedance, within normal range of likely values; X indicates that feedback is critically dependent on external impedance. This is not necessarily had, as it may
be the purpose for which the feedback is applied.
Fig. 5.
Fig. 3.
Current -derived
Voltage -derived
Fig. 4.
tb A O
APRIL 1968
EXPERTS AGREE ... the Heath AR -15 is
the world's most advanced stereo receiver
Electronics World, May'67: "Heath implies strongly that the
AR -15 represents
High Fidelity, Dec. '67: "The AR -15 has been engineered on
an all-out, no -compromise basis."
new high in advanced performance and circuit
concepts. After testing and living with the AR -15 for a while,
we must concur."
Hi-Fi /Stereo Review, May '67: "Several people
Popular Electronics, Jan. '68:
reviewer's mind that the AR -15 is
have com-
mented to us that for the price of the AR -15 kit they could buy a
very good manufactured receiver. So they could, but not one that
would match the superb overall performance of the Heath AR -15,"
"There is no doubt in your
a remarkable musical in-
Popular Mechanics, Nov. '67:
AR -15 is an audio Rolls Royce
Modern Hi-Fi & Stereo Guide, 1968: "I cannot recall being
so impressed by a receiver... it can form the heart of the finest
Heathkit's top -of -the -line
Popular Science, Dec. '67: "Top-notch stereo receiver"
"it's FM tuner ranks with the hottest available" ... "it's hard to
stereo system."
Audio Magazine, May 1967: "The entire unit performs con-
imagine any other amplifier, at any price, could produce significantly better sound."
siderably better than the published specifications."
here's why the experts agree .
The Heath AR -15 has these exclusive features:
Best sensitivity ever ... special design FM tuner has 2 FET
Adjustable Multiplex Phase Control
rf amplifiers and FET mixer
stereo reception
Best selectivity ever ... Crystal filters
Best limiting characteristics ever
in IF
... no other has
like having 8 trans-
in IF
perfect response, no alignment
formers in IF
Most power output of any receiver
Music Power
... enormous reserves
response when desired
Front panel Input Level Controls
Ultra -low distortion figures
hidden from view by hinged door
Transformerless Amplifier
Ultra -wide dynamic range phono preamp (98 db)
superior regulation
Two Tuning Meters
sures no overload regardless of cartridge type used.
Unique Noise -Operated Squelch
station noise before you hear it
if you wish
... silences
electrostatic and magnetic
for center tuning and maximum
used as volt -ohmmeter during assembly of kit
Positive Circuit Protection
... Zener-diode
current limiters
plus thermal circuit breakers protect unit from overloads and
short circuits
"Black Magic" Panel Lighting ...
no dial or scale markings
show when receiver is turned off, thanks to exclusive tinted
acrylic dual -panel design
all monophonic programs
Heath AR -15
... also
2 IC's.
switches to stereo only if quality of reception is acceptable
... you adjust to suit
Stereo -Only Switch
All -Silicon transistor circuitry ... 69 transistors, 43 diodes,
hushes between unusually elaborate and
Unusual Stereo Threshold Control
accessible, yet
Capacitor coupled output ... protects your speakers
Massive power supply, electronic filtering ... for low
... easily
direct coupled drivers and
outputs for lowest phase shift and distortion
150 Watts of
harmonic distortion less
watt or full output
IM distortion less than
0.2% at 1 watt, less than 0.5% at full output
Ultra -wide power response ... 6 Hz to 50,000 Hz, 1 db,
at 150 Watts Music Power
than 0.2% at
for cleanest FM
Tone Flat Switch .. bypasses tone control circuitry for flat
Integrated Circuits
like having 20 transistor stages in IF
... Kit $329.95* ... Assembled $499.50*
'optional walnut cabinet,
HEAT' KIT 1968
COMPANY, Dept. 41
Benton Harbor, Michigan 49022
In Canada, Daystrom Ltd.
Enclosed is $
Now with more kits, more color,
Fully describes these along with
over 300 kits for stereo/hi-fi.
color TV, electronic organs, electric guitar & amplifier, amateur
radio, marine, educational, CB,
home & hobby. Mail coupon or
write Heath Company, Benton
Harbor, Michigan 49022.
plus shipping charges.
Please send
Stereo Receiver(s).
(quantity & model)
Please send FREE Heathkit Catalog.
Na me
specifications subject to change without notice.
HF -213
Check No. 45 on Reader Service Card
APRIL 1968
such that (1+AB)=10
Fig. 6. The question of what outpu impedance is meant, discussed in the text, refers to these impedances.
can't modify the actual external load
impedance connected, can it?
The only way to clarify this is to
take an example. Suppose we have
an output stage using pentode tubes
or transistors in which the source resistance, without feedback, is ten
times the design load value. Just to
put in some figures, suppose the design load impedance is 10K and the
source resistance is 100K (Fig. 6).
Now we apply 20 dB voltage -derived feedback to this amplifier, reducing its gain by a factor of 10.
What is the output impedance
changed to?
First we must ask what gain is reduced by a factor of 10? In other
words, under what condition is the
feedback 20 dB? We'll presume the
factor intended in this statement is
the gain with the load connected.
Without feedback, removing the
load would cause the output voltage
to rise about eleven times (assuming
the input level is low enough so that
the amplifier does run into serious
distortion when the load is removed) .
Looking at the output impedance
as a parallel combination of the
100K source and the 10K load,
which is how the feedback connection "sees" it, the value is about 9K.
Feedback at 20 dB will reduce this
effective value to one tenth, or 900
But the external load of 10K has
not changed. This means the internal (source) resistance must have
changed to a value that will make the
parallel combination of the two come
to 900 ohms. To do this, the source
resistance must have a value of 1K.
Viewed this way, then, the 20 dB
feedback has reduced the source resistance from which the 10K load
works from 100K to 1K. It begins to
look as if we have made a liar out of
our formula. Feedback of 20 dB
should change impedance by 10:1,
not 100:1. Actually, we're talking
about different feedback values.
To think of source resistance apart
from load impedance, which we do
when we regard the load impedance
as external to the amplifier, we
should consider the gain without the
load resistance connected, ideally.
This may not be practical, for a reason we shall mention soon. But for
the moment, consider the gain
change without the load connected.
Removing the load will cause the
output voltage to rise about 11 times;
connecting the feedback will now reduce the gain by 100 times, because
11 times as much gets fed back as
a pushpull output shows
how source resistFig.
Pie -desg
curves for
- - - - - - - Source
ance changes with
loading (dashed
there was when the load was connected, relative to the output.
Previously, the feedback was 9
times input, to make (1 + AB) =
10, so now feedback is 9 x 11 = 99
times input, to make (1 -I- AB) =
100. So source resistance is reduced
by a factor of 100, which was the
value calculated by the other
Different feedback methods applied
to voltage type input: (a) series injection
is sensibly independent of external source
impedance; (b) shunt injection is critically
dependent on the ratio of R1 and R2,
where R2 is the internal resistance of the
external source.
Fig. 8.
The reason this method may not
be practical is that effective source
resistance is actually dependent on
the load value connected. When the
load is disconnected, the output may
not rise by precisely the factor calculated from the source resistance.
It invariably changes when the
amplifier is operating open -circuit
because a different load line is applied to the output tube or transistor
( Fig. 7) We discussed some aspects
of this variation of source resistance
in a previous article in this series.
That's an example of ambiguity in
definition of feedback, as related to
the output end. The input end also
presents problems in defining the
precise condition. With tube or FET
circuits using series injection, we
have little problem. The voltage delivered to the grid of the tube or the
control electrode of the FET is substantially the sum of the external input voltage and the feedback voltage
(Fig. 8).
(Continued on page 69)
APRIL 1968
99.95 KIT, 154.95 ASSEMBLED
89.95 KIT, 129.95 ASSEMBLED
the evolution of high fidelity, there have been some
FM multiplex, and transistorization, to give some examples. Each of those changes
left its trail of obsolete equipment, frequently replaced with
much higher priced models. Through these periods of
change, Dynaco has maintained a level of quality so high
that our equipment is always current, never obsolete, and
always adaptable to the newest useful innovations.
Dynaco's underlying philosophy is to deliver exceptional
performance from designs so carefully and progressively
engineered that they defy obsolescence. We add new products only when we feel that they can make a contribution of
value to music reproduction. In each Dynaco high fidelity
component the total value of the separate parts is greater
than what you pay for the finished product,. and you can
save even more by buying the kit.
Dynaco's separate components give you the ultimate in
flexibility and ease of installation. They can be interchanged
with full compatibility, not only with Dynaco units, but with
any other similar designs which are generally accepted as
being of the finest quality. No industry innovation can make
your system obsolete, and future changes, such as an
"revolutions"-the stereo record,
increase in amplifier power, can be easily and economically
The quality of performance obtained with the FM -3 tuner,
PAT -4 preamplifier, and the Stereo 120 power amplifier
cannot be matched in any single package regardless of promotional claims. Other Dynaco units which can interchange
with this system will also give similar results at lower power,
or with a bit less control flexibility at still lower cost, depending on the units chosen.
Whether you compare Dynaco with others by listening or
by laboratory test, you will find that Dynaco gives sound
closest to the original-with lucid clarity, without murkiness, noise or distortion. Every unit-whether purchased as
a kit or factory assembled, is assured of delivering the same
specified quality, for our reputation has grown through
directing our design efforts towards perfection rather than
to the planned obsolescence of yearly model "face-lifts."
You may find that your dealer does not have some Dynaco
equipment in stock, however, for the demand greatly exceeds
our ability to produce for a rapidly growing audience. Quality
is our first consideration, so we must ask your patience.
We believe you will find it is worth the wait.
159.95 KIT, 199.95 ASSEMBLED
Write for descriptive literature and complete specifications.
APRIL 1968
PA. 19121
5 -in. professional types with edge
lighting. Bias Freq.: 100 kHz. Monitoring:
Front -panel switch for ea. channel. Dimensions: 171/2 -in. high, 19 -in. wide, 9 -in.
deep. Price (basic machine): $1790.00.
The Crown CX822 pictured here
the finest tape recorder
that has been reviewed in these pages.
In addition to delivering phenomenal
performance, it incorporates numerous
features and refinements that place
this machine in a class by itself.
The Elkhart, Indiana manufacturer
has, for example, introduced a computer -type logic system to prevent destructive operations; electronics is
substituted for mechanical mechanisms
in many instances; tape handling has
been made more gentle and faster than
ever before, while tape tensions have
been drastically reduced; editing has
been greatly simplified; construction
appears to be rugged enough to withstand parachute drops; and Old -World
craftsmanship is apparent at a glance,
quickly substantiated by handling the
well -engineered recorder.
The Crown Model CX822 recorder
is the latest model in the 800 series of
recorders from Crown International.
It consists of two detachable parts: the
tape transport and the electronics assembly. Since the tape heads are part
of the tape transport, all adjustments
to the electronics affecting the combined performance of the transport and
electronics are performed when the
two are mated. So for descriptive purposes, let us consider the CX822 as one
unit, breaking it down functionally,
rather than physically.
To begin with, the CX822 is a two track machine which works at three
speeds. This means that the necessary
speed changes (see Fig. 2) and selectable equalizations are built-in.
(Crown's Model CX824 is a four -track
unit, with high speed at 71/2 ips and low
at 17/s ips.) The machine accepts standard, plastic, EIA reels directly (see
Fig. 3) onto the turntable or 101/2 -in.
NAB reels with adaptors, which are
furnished with the machine (Figs. 4
and 5). Each turntable is driven by a
1250 rpm capacitor -run torque motor
with self -aligning bearings. Turntable
braking is accomplished by electric
means, whereby the motors are slowed
by applying d.c. voltage to them. This
contrasts with the solenoid -actuated
mechanical braking system of most
comparable machines. The type of differential electro-dynamo braking used
here is a patented feature of Crown
transports, whose brakes did not grab,
is probably
This Month:
Crown CX822 Stereo Tape Recorder
AR Stereo Integrated Amplifier
Garrard SL -95 Automatic Turntable
Crown Model CX822 2 -track
Stereo Tape Recorder
MANUFACTURER'S SPECIFICATIONSTape Speeds: Three, equalized; 15, 71/2,
33/4 ips. Timing: 99.8°/o or 1.8 sec. in 15
min. and adjustable to ±0.05°/o short term.
Wow and Flutter: 15 ips, 0.06°/o; 71/2 ips,
0.09°/o; 33/4 ips, 0.18°/o. (Guar. max. for
record, playback.) Record/Play Frequency
Response: 15 ips, ±2 dB 30 to 30 kHz;
71/2 ips, ±2 dB 30 to 20 kHz; 33/4 ips,
±2 dB 30 to 10 kHz. Signal -to -Noise Ratio:
-57 dB @ 15 ips; -56 dB @ 71/2 ips,
-50 dB @ 33/4 ips. Stop Time: One-half
in. @ 33/4 ips; 1 -in. @ 7'/2 ips; 3 sec. from
full rewind on 101/2 -in. reel. Start Time:
Under 0.1 sec. Wind and Rewind: 1200
ft. in 45 sec.; 2400 ft on 10'/2-in. reel in
58 sec. Reel Size: 101/2 -in. (NAB) max.;
5 -in. min. Distortion: Approaches threshold of measurability. Inputs: 2 per channel; high -Z mic. or line level. Opt. input
transformers for low -Z mic. Tone Controls: Bass, 15 dB atten. or boost at 30 Hz;
treble, 15 dB atten. or boost at 15 kHz.
Outputs: Two per channel, 600 -ohm
unbal. One low -Z output (stereo phone
jack) on front panel. Motors: Three. Drive,
Hysteresis synch. drive motor; Reel,
2 capacitor -run torque motors. VU Meters:
jerk or need adjusting during our extensive tests, and work extremely well
in bringing the tape to a smooth, gentle,
rapid stop. A positive temperature coefficient resistance is used to provide
the braking differential.
We tried to make the deck misbehave by stopping a roll of super -thin
1/2 -mil tape at high speed by rocking the tape back and forth, and by
other tortuous combinations. Not only
did we fail to foil the machine, but
once motionless, the tape at the gate
was limp (not under tension) and no
stretch marks were to be found anywhere on the tape. All this despite its
breakneck wind and rewind speed. It
took exactly one minute to smoothly
wind 1800 feet of 1 -mil Mylar tape between 7 -in. reels. The only apparent
problem with this kind of braking
would occur if there was a loss of electrical power during rewind, say. But
the mechanical simplicity, reduction of
maintenance and potential reliability
of the CX822 far outweigh such an unlikely occurence as a power failure at
the precise moment of rewind.
The stainless steel capstan shaft is
centerless ground, hardened and highly
polished. Its tip is of non-magnetic,
chrome -plated stainless steel, and it is
concentrically aligned with a four pound flywheel of nickel -plated steel.
The assembly is mounted in a %-in.
thick aluminum "tunnel" casting, five
in. long, with self -aligning Oilite bronze
bearings. The flywheel is driven by a
centerless ground -neoprene drive belt
Fig. 2-Drive pulley and capstan flywheel
system shown in 71/2 ips position. The flywheel, driven by a seamless neoprene
belt, is mounted on rear of capstan. Note
flywheel bearing support. Belt can be
switched from 71/2 to 33/4 ips from front panel push rod. The 15 ips speed change
is done manually by stretching the band
over the largest pulley. The belt can be
replaced in seconds, without removal of
other parts.
APRIL 1968
The SM60 cannot be stereotyped-is equally at home
in the studio or in the field-stand-mounted or handheld-in uses as diverse as outdoor sporting events
and elaborate variety shows. Small wonder that audio
engineers have called it one of the most versatile
omnidirectional dynamics they've ever encountered,
for the SM60 is a unique combination of good -looks,
strength, performance and economy.
The smooth, wide -range response provides cleanest,
natural reproduction of both speech and music. A very
effective built-in wind and "pop" filter protects against
undesirable effects of close -talking.
Lustrous, non -glare metallic finish and tailored -to -the -
hand dimensions provide striking on -camera appearance and superior handability. Specially reinforced
machined -steel case front is designed to take abuse
that would ruin other microphones-you can drop it
on its nose without damage to The internal structure!
Efficient windscreen and front end are quickly and
easily removable for cleaning.
Best of all, it is priced competitively with conventional
"workhorse" microphones. Why not check out an SM60
now? See your Shure Professional Products Distributor,
or contact Mr. Robert Carr, Manager of °rofessional
Products Division, Shure Brothers, Inc., 222 'rlartrey
Ave., Evanston, Ill. 60204-Phone 312 - 328-9000.
S M60
matches well in
Specifically designed for radio, TV, motion pictures
sound with stand or desk mounted units. Smoothly-contoured, machined steel case and recessed grille for minimum clothing noise. Exclusive
snap -in mounting of microphone for greater convenience, security.
"Positive Lock" lavalier goes on in an instant-provides simple, noiseless position adjustment. Extra -flexible, kink -free rubber cable is easily
© 1967
Shure Brothers, Inc.
Check No. 49 on Reader Service Card
APRIL 1968
Fig. 3-Turntable set to accept
7 -in.
tape reel.
Fig. 4-Turntable with NAB reel adaptor
in place.
5-Locking tape -reel holder is screwed
on for use with all reels. Tightening holder
compresses adaptor, causing adaptor
spring to spread, and thereby applying
tension to inside of NAB hub to hold it
which slips over the flywheel and one
of the three motor -drive pulleys. The
capstan motor is a huge hysteresis
synchronous device, permanently lubricated, ball-bearing drive motor.
Ducted forced air flows over the drive
motor, forced by its fan, and is forced
out the side of the transport. An
appropriate cutout is made in the
case for this. The pressure roller
that engages the capstan to pinch the
tape and move it is made of neoprene,
with a full Oilite bearing supporting
the roller. The neoprene itself is
ground to ±0.001 -in. concentricity.
Glass rod lifters lift the tape onto the
heads in the play and record mode,
releasing (thereby removing tape from
the heads) during FAST FORWARD, REWIND, and STOP modes. See Fig. 6. A
plug-in solenoid, designed for continuous duty, closes the gate, raising the
tape lifters and pressure roller. See
Fig. 7. Once the solenoid is seated,
over 20 pounds of force applied to
the pressure roller is required to unseat it. The extent to which Crown has
gone to assure a friction -free, concentric, noiseless tape drive and guiding
system apparently paid off because
even at 33/4 ips, its lowest speed, the
deck had 0.1% flutter and wow at most.
At 71/2 ips it was 0.07%; at 15 ips,
0.05%-a remarkable achievement, living up to the manufacturer's claims.
One of the unique features of the
deck is its tape motion system, which
is controlled by either the built-in, illuminated pushbuttons (four) or via
remote control. Five leads are required
for external control of FAST FORWARD,
STOP and
modes. Either momentary closure of a
4-V line at 40 mA or an external supply of 1.55 V as 5 mA will operate all
four modes. But getting back to local
control, the trick is in the built-in integrated -circuit "computer" system
that stores the pushbutton commands,
its memory retaining only the last command given it. It compares the last
command with the present state of the
deck-that is, the direction in which
the tape is going and how fast-and
executes that command in the safest
way. The tape motion and direction
sensor is shown in Fig. 8. For example, if the machine is going FAST
FORWARD and the green PLAY button
is pressed, the tape will come to a complete stop, the red STOP button is automatically illuminated (we didn't press
it, remember) followed by the gate
closing and the tape going into play
motion as the green PLAY button lights
up. All this without hands. Any command or combination of commands can
be safely given at any time. If multiple commands are given to the machine, it will obey the following priority
rules. (1st) REWIND or FAST FORWARD
(except when in RECORD mode) ; (2nd)
PLAY; (3rd) STOP. We found the tape
motion command system to be as foolproof as Crown says it is, and could
not beat the computer by design or by
An automatic tape sensor is provided
in the form of a photocell and lamp on
the left end of the head assembly. This
gives a continuous stop command whenever tape runs out or a transparent
"window" in the tape is sensed. Because of the priority command setup,
the STOP command may be overridden
by holding down any other command.
As was mentioned earlier, the control
system performed flawlessly. In professional recording and editing application, the Crown's computer system acts
as a time saver, which simplifies operation.
Every part of the deck is easily accessible. Part of the back swings out on
hinges; the rest comes off with removal
of a few screws. All motors are easily
removable, as is the head assembly and
printed -circuit cards. Relays are unplugged. Controls as well as connectors
can be replaced with easy access (Fig.
11) everywhere. Surely, the CX822 is
a serviceman's dream, considering the
unit's inherent complexity.
The CX electronics, Fig. 12, is a
solid-state, modular record/playback
amplifier. Its purpose is to accept and
condition input signals to properly
drive tape recording heads and to provide playback facilities and proper
equalization. The input circuit accommodates two inputs per channel, which
are individually mixed on the front
panel. Either or both can be high- impedance microphone or line level. A
low -impedance option converts the
high impedance mike inputs to low
impedance and adds a balanced, low
impedance +12 dBm 600-ohm output
level which can be adjusted internally
between -20 dBm and +18 dBm. The
standard output level is +12 dBm unbalanced. The preamplifier response is
essentially flat over the 10 Hz to 100
kHz range, exclusive of the required
equalization and bias traps.
Figs. 6 and 7-(Left) Tape head assembly, gate open. (Right) Tape head assembly, gate
closed (pinch roller up against capstan). Note elaborate guiding system of glass rods and
chrome plated, hardened steel guides. Lever at lower right is used to manually close
the gate for editing. Slide switch, at lower left, removes take-up reel torque for easier
editing. Note easy access to heads from all angles. Azimuth and tracking are independently adjustable and are factory set and sealed. Molded cables connect to head and the
entire head assembly. The assembly is removable and head covers snap off easily. The
leaf -spring loaded pressure pad applies just a slight amount of tension to the tape
against the record head. This might be used as an added flutter filter or to insure perfect
contact at low speeds.
The bias oscillator consists of a
pair of push-pull connected power
transistors operating into a ferrite cupcore assembly. The circuit produces a
clean 100 kHz signal for bias and erase.
Bias current is adjustable from the
front panel, using the VU meters as
relative indicators. Erase was highly
effective, producing a level better than
61 dB down from 0 VU. The 5 -in. illuminated and accurately calibrated VU
meters indicate any of four selector switched modes of operation. They can
show input level, output level of the
tape, output level leaving the machine
after the output level controls, or a
combined source and tape level which
is used for echo effects .They also show
bias voltage, which is proportional to
bias current, and calibrated to correspond to 0 VU. Output level of the machine is controllable at the front panel
and the same controls are used to regulate monitor headphone levels during
Front panel electronic controls include: selector switches for output and
meter, separate treble and bass controls for each channel that are usable
for recording and playback, four input
level controls; separate output level
controls, a play -record switch that has
a press -to -move -button safety interlock
and separate positions for reading bias
voltage with the VU meters, and bias
adjustments. All these controls operate
separately and independently on each
channel and are sensibly laid out across
the front face. The 3 -speed equalization switch is common to both channels.
The versatile control setup, coupled
with a high signal-to-noise ratio, makes
this machine useful for such applications as "sound on sound" recording
where tone shaping is required, for example.
Since the record function is interlocked mechanically, electrically and
visually, it's almost impossible to record or erase or ruin a recording by
accident. For example, the deck won't
go into REWIND while recording, though
it will go into REWIND from PLAY. Such
awkward intentions are common even
in professional use, when confusion and
hurry conspire to overide commonsense rule, and it seems that tape machines can never be too goof-proof.
A regulated 30V power supply is
employed to make the CX electronics
nearly independent of line voltage variations, and to insure stable operation
in all modes when the load changes
suddenly. The supply is built-up on a
printed circuit card. Additional filtering and de -coupling of the power supply lines is used within the various
circuits, where needed.
APRIL 1968
The Crown CX822 easily met its specifications. Its frequency response was
flat and balanced, with no evidence of
peaks. The measured playback response at 71/2 ips, shown in Fig. 10,
comes out to 50 to 15,000 ±1.2 dB, at
60 dB signal-to-noise ratio. At 3% ips
the playback signal-to-noise ratio measured 57 dB. The measured record/
play frequency response, using Scotch
203 tape, is shown in Fig. 10. It can be
summed up as: 30 to 28,000 Hz ±2 dB
at 15 ips, 20 to 20,000 Hz ±2 dB at 71/2
ips, and 20 to 10,000 Hz ±2 dB at
33/4 ips. The measured frequency response closely matched the individual
factory -run curves which accompanied
the sample machine.
Harmonic distortion of the record
electronics was less than 0.2% at 10
kHz. A 10 kHz signal recorded at -10
VU yielded a record/play distortion of
less than 1%, measured while recording. It was even less in the other parts
of its frequency range, as well as when
playing back (not recording simultaneously) . This is outstanding. IM distortion of the record electronics was better
than 0.1%. Off the tape, while recording, it was 1.5% on left channel and
1.3% on right channel, which is also
especially fine. The record/playback
signal-to-noise ratios were measured
at 15 ips, yielding -55 dB left, -57 dB
right; 71/2 ips, produced -56 dB left,
58 dB right; 3% ips, -54 dB left,
56.5 dB right. Crosstalk at 1 kHz
was down a phenomenal -63 dB,
which is really negligible since it is
below the noise level.
The minimum input required for 0
VU was 0.1. mV through the low-level
high -impedance mike input and 0.5 V
through the high-level line input. Thus,
this is a highly sensitive machine, suitable for every conceivable type of input. The VU meters, which are driven
by their own drive circuit, respond the
same regardless in which sensitivity
range the main amplifier is operating.
There is also plenty of level for monitoring stereophones-no matter how
inefficient a pair is chosen. A standard
0 VU recorded tape produced 2.5 V out.
To truly appreciate this machine,
you must use it, of course. At the
outset, tape threading is delightfully
simple and, therefore, accomplished
quickly. There are no tensed compliance arms around which the tape must
go. Just shove the tape into the slit
formed by the head covers and you're
in business. Editing facilities are great,
too. There's a newly designed editing
tape (cue) lifter, for example, and under the head cover is a slide switch to
shut power of the takeup reel motor,
Fig. 8-The tape motion and direction
sensor is installed on rear of the supply
motor, as shown above. When the supply reel moves the slightest amount, it
causes the shiny disc at center to move
from its rest position in the same direction
as the motor turns. After about 5 deg. of
rotation, the disc reaches its stop and
halts. During its journey, however, its slits
(not seen) interrupt an appropriate light
beam created by the lamp whose base is
visible below the motor. The light (or ab sense thereof) triggers a photocell which
energizes a relay through gates. When the
disc begins to turn in the opposite direc-
tion, it activates a different photocircuit,
which then energizes a second relay. The
information gleaned by the motor and
direction sense circuit is used by the computer to come up with proper commands
to control tape motion.
Fig. 9-Tape control pushbuttons are attached to the rear of a printed circuit card
(bottom -left). Take-up reel motor is at
top, with ballast resistor and capacitor on
swing -away panel at left.
thus simplifying editing jobs. You can
"rock" between fast forward and fast
rewind to your heart's content as a result of the CX822's fool -proof control
system. Tape tension limits are set by
a switch for small -size reels or for the
larger type.
Playing back first -generation transfers from original masters, the sound
produced through the Crown CX822
was peerless. When recording and playing back from records and FM broadcasts, there was absolutely no aural
difference between the original and the
copy at 15 ips. The same held true at
71/2 ips, though, theory says, there
should have been.
The machine was taken to a night
club, where it was pushed, kicked (in
its case) and, in general, treated
rather callously to simulate what might
be expected under normal conditions.
The rugged unit, with its 50% thicker
panel and added structural members
(as compared with previous models),
continued to operate like the professional -quality unit it is. Recordings
made of piano music and a Regina
music box were entirely faithful to the
original, thanks to the CX822's low order of wow and flutter, among other
highly prized characteristics. We had
to use good condenser mikes to fully
appreciate the quality of sound that
this machine is capable of recording.
Using a pair of calibrated ribbon types
in our possession, the Regina music box
exhibited better "highs" than evident in
playback, for example. But the difference was already apparent before going onto the tape, as monitored via
headphones. Switching mikes produced
a recording almost indistinguishable
from the real thing.
Is the 15 ips speed worthwhile? For
master tapes, undoubtedly yes. Insofar
as our ears are concerned, though, the
"extra" sound quality achieved over
71/2 ips is only a wee bit better in high -
D -10
Right channel
5k 10k
30k 50k
10-Record/playback response of Crown CX822 stereo tape recorder.
frequency response, and then on music
which has high-energy content here
(say, above 16 kHz). The truth is, that
the performance of this machine at 71/2
ips is so good that, except to meet a
professional recording need or for playing back 15 ips tapes, the 71/2 ips speed
would serve equally well (as offered in
the model CX824).
Aside from large size and heavy
weight, which cannot be avoided, the
only area where the bull's eye of perfection went very slightly astray was
the NAB reel adaptors. The problem
here, shared by most other machines
which offer them, is that when you
screw on the cap to spread the spring
which holds the hub, the spreading
does not take place evenly. This causes
very small eccentricities, which, at high
speed, results in the tape not being
wound as smoothly as it could. [Crown
will haue a new NAB reel adaptor
Fig. 11 -Underside of electronics chassis.
available in the near future which
overcomes this minor deficiency. The
center hub will be larger, and it will
include three "feet" so that it can't
twist due to spring tension-Ed.] But
this aside, the new Crown CX822 is
capable of providing the most faithful
reproduction of sound through the
magnetic recording medium that we
have observed to date. And it does it
in as foolproof and as easy a way as
we've seen. It is the machine for the
tape enthusiast who wants and can afford the best.
(Accessories supplied with test sample were four CX2 playback amplifiers,
$180; a 2CX6 output amplifier, $50;
4/X low-impedance balanced mike inputs and outputs, $100; model X carrying case, with complete access to front
and rear of the recorder, $59.)
Check No. 48 on Reader Service Card
Fig. 12-Back view of complete electronics chassis.
APRIL 1968
world of your own on
"Scotch" Brand Dynarange®Tape.
Great moments in music
happy times at
home and away-capture whatever sound
you want to save on "Scotch" Brand
"Dynarange" Recording Tape. "Dynarange"
delivers true, clear, faithful reproduction
across the entire sound range. Makes all
music come clearer
... cuts
gives you fidelity you didn't know
your recorder had.
And "Dynarange" saves you money, too!
Delivers the same full fidelity at a slow 33/4
APRIL 1968
w: 201
speed that you ordinarily expect only at 7%
ips. The result: You record twice the music
per foot
use half as much tape
25% or more in tape costs! Lifetime silicone
lubrication protects against head wear, assures smooth tape travel and extends tape
life. Isn't it time you built your own private
world of sound on "Scotch" Brand "Dynarange" Recording Tape?
magnetic Products Division
Check No. 53 on Reader Service Card
1-Front panel of the new AR integrated amplifier is shown above. Below it
is the AR's power supply, which features
a standby power supply to eliminate
"thumps" when turning the unit on.
AR Stereo
Preamplifier -Amplifier
Power Output per channel (both channels
driven): 60 watts rms at 4 ohms; 50 watts
rms at 8 ohms; 30 watts rms at 16 ohms.
IM Distortion at any power level to rated
output: less than 0.25°/o. Total Harmonic
Distortion at any power level to rated: less
than 0.5°/o at any frequency from 20 Hz to
20 kHz. Frequency response: ±1 dB, 20 Hz
to 20 kHz. Signal to noise ratio: phono,
57 dB, ASA "C" (flat) weighting; tape and
tuner, 75 dB, "C" weighting. Input sensitivity (for full output): phono, 2 mV to
5 mV, adjustable at 1 kHz; tape and tuner,
0.2 volts. Outputs: tape recorder and 4-16
ohm speakers. Damping factor: 20 for 4 ohm speakers, 40 for 8 -ohm speakers, 80
for 16-ohm speakers, at any frequency
above 75 Hz. Dimensions (with optional
wood enclosure): 153/4 in. wide by 4'/3 in.
high by 10 in. deep. Price: $225.00. Opt.
oiled -walnut enclosure, $15.00.
convenient "external ground" post. A
view of the rear connection panel is
shown in Fig. 2.
The entire amplifier is enclosed in a
well -ventilated, black anodized, aluminum cover. The package is attractive
enough for shelf installation even if you
omit the optional wooden enclosure.
It was when we removed the cover
of the amplifier that we began to appreciate the ruggedness of this design. The
power transformer is massive, reminiscent of the old vacuum tube days. This
accounts for the fact that power output
is almost the same whether one or both
channels are driven to full output-the
power supply just never "quits."
Speaking of power supplies, a novel in -
Rear panel shows heat -sink arrangement for output transistors.
Fig. 2
novation here involves the use of two
complete power supplies. The first, or
standby supply, actually energizes the
earlier stages of the amplifier even
when the amplifier is turned off! Consuming only a mere trickle of power,
this feature eliminates the loud thump
usually associated with the turning on
of a high-powered solid state amplifier.
Each phono preamplifier consists of
two NPN transistors which utilize
feedback to accomplish the very accurate (within 0.5 dB from 30 to 20,000
Hz) RIAA equalization. Gain of each
preamp is externally adjustable to suit
cartridge outputs from 2 to 5 millivolts,
and for insuring identical gain of the
preamp channels. Both preamps are
mounted on the first of three independant printed-circuit modules.
The second P.C. module contains six
NPN transistors to accomplish the
necessary voltage gain and tone control compensation. The tone controls
are of the familiar feedback variety
which vary both the degree of bass and
great surprise that
Acoustic Research's first entry in the
control/amplifier field should be a real
"powerhouse" of a unit. Long noted for
its excellent acoustic suspension speaker designs (which generally require
more amplifier power for successful
operation than more efficient types) ,
AR would hardly be expected to offer
an amplifier that didn't fill the bill for
its own speaker line.
The specifications listed above are
some of the most conservative ever
noted. Although the industry has
agreed to use "music power" ratings,
no doubt because they result in some54
what higher power capability figures,
AR chooses bravely to hold to the more
conservative "rms" power figures.
The front panel of the AR amplifier
is so startlingly simple in arrangement
that it belies the sophisticated circuitry
behind it. It is, as shall be pointed out
later, perhaps a bit too simple for a
control amplifier in this category, omitting certain features which have come
to be expected nowadays (though many
are not used by owners). Scanning
from left to right one encounters a
selector switch with only three positions: "phono," "tuner" and "tape."
Next are the dual concentric pairs of
"bass" and "treble" controls, clutch
operated for individual adjustment of
left and right channel tonal compensation. These are followed by a concentric
pair of controls, the inner of which is
the usual channel balance control. The
outer knob of this pair is a mode switch
whose positions include "mono," "null"
and stereo." At the extreme right is the
volume control, which also turns off the
instrument in its extreme counterclockwise position. The only other items
we could find on the front panel were
a tape-monitor slide switch and a bright
red indicator light at the extreme upper right of the panel. Figure 1 illustrates the Spartan simplicity of this
layout. Knobs, of the heavy turned metal type, are gold colored, as is the
entire dress panel.
As for the rear panel, it contains the
usual pair of speaker terminal strips
(color coded for ease of connection, and
adequately separated to prevent accidental shorting) three pairs of input
jacks (also color coded to correspond
with AR's interconnecting cables supplied on its turntable), a pair of tape
output jacks, concentric phono input
level controls (adjusted to match the
phono cartridge at installation), two
convenience power outlets for auxiliary
equipment (one switched, one non switched), two speaker line fuses as
well as an overall line fuse, and a very
3-Internal layout reveals PC boards,
heavy heat sinks, large power supply and
driver transformers.
4-Tone control range with settings for
and full rotation in either direction
from center.
1/3, 2/3
+10 _____
¢ -20
10k 20k
is sacred anymore.
Fisher has just come out
with a stereo receiver
that sells for less than $200.
Thirty years ago, Fisher built
high -cost, high -quality music
systems for a small, closely knit
group of music lovers and engineers.
And although the group has
grown in number through the
years, it has remained basically the
same: a group of music lovers who
demand the finest audio equipment
available, regardless of price.
But times have changed.
Practically everyone drives a car.
Most people have telephones. Why
shouldn't everyone own a Fisher?
So, though we realize that a
few diehard Fisher owners from
the old days will view it with alarm,
we're introducing the Fisher
160-T, priced at $199.95.
The 160-T FM -stereo receiver,
though slightly less powerful and
a bit smaller than other Fisher
receivers (it measures 151/4" x 31/8"
x111/4" deep), is every incita Fisher.
Its amplifier section has 36
watts music power (IHF)-enough
to drive a pair of good bookshelf
speaker systems at full volume
without distortion. Harmonic
distortion is very low: 0.5%. And
the power bandwidth is broad:
25-25,000 Hz.
The tuner section is just as
good as its counterpart in higher priced Fisher receivers. It has 2.2
microvolts sensitivity, while
signal-to-noise ratio is 60 dB or
better. Like all Fisher receivers,
the 160-T will pull in weak, distant
signals and make them sound like
strong, local stations.
Stereo stations are signalled
by Fisher's patented Stereo Beacon *
which automatically switches
between stereo and mono. And
FM -stereo separation is all anyone
could want (35 dB or greater).
As you might expect from a
Fisher receiver, the 160-T employs
silicon transistors, including 2
FET's and 3 IC's. And Fisher's
exclusive Transist-O-GardTM
circuit protects the output
transistors from ever overloading.
The new Fisher receiver has a
versatile control panel, with
Baxandall tone controls (normally
found only in more costly
equipment), a 3 -way speaker
selector (main -off-remote) and a
loudness contour switch that
boosts bass and treble automatically at low listening levels.
The 160-T, with most of the
exclusives found on Fisher's more
expensive models, has some
unique features of its own. Like
Tune-O-Matic pushbutton tuning,
which allows you to pretune your
five favorite stations and switch to
APRIL 1968
The Fisher 160-T
Mail this coupon for
your free copy of The
Fisher Handbook
1968. This 80 -page
reference guide to
hi-fi and stereo also
includes detailed information on all
Fisher components.
Fisher Radio Corporation
11-35 45th Road
Long Island City, N.Y. 11101
Overseas and Canadian residents please write to Fisher Radio
International, Inc., Long Island City, N.Y. 11101.
*U.S. Patent Number 3290443.
them instantly, at the touch of a
button. This switching is
accomplished electronically, and
bears no relation to inaccurate
mechanical pushbutton tuning.
(Normal tuning across the FM dial
is, of course, also provided.)
And, as we've said, the most
unusual feature of all is the price,
There may be some raised
eyebrows among the more
conservative Fisher owners, on
account of the low price of our
new receiver.
But think of the thousands of
happy new Fisher owners.
Check No. 55 on Reader Service Card
á 0.20
THD at
8 -ohm
load, both
channels a.,.,o.,
... ."
-0 05
5-IM and THD measurements. (Note that this is an expanded
scale, with the graph's distortion percentage ranging from 0 to 0.3.)
treble boost and attenuation, as well as
the crossover frequency. Typical tonal
response curves at intermediate and extreme settings are shown in Fig. 3.
The third P.C. board contains four
transistors per channel and delivers the
necessary amplification and power to
the driver transformers (which are
larger than some output transformers
we have known). A pair of RCA AMP 2947 transistors (themselves used in
low -power output amplifiers) are used
to drive a pair of AMP -2919 output devices, mounted to individual, massive
finned heat sinks for each channel.
Two other transistors are found in the
amplifier, for a total of 28 transistors.
One of these is used as a regulator in
the power supply, while the other acts
as a phase inverter in the nulling circuit.
fier about eight years ago-thought it
was a good idea then, and wondered
why it wasn't picked up by other manufacturers. The Nuts, position of the
mode switch is used in conjunction with
the balance control to achieve electrical
balance of signal input sources. In the
Nuts, position, one input channel is reversed in phase, with unity gain; it is
then mixed with the other channel, and
the combination is fed to the amplifier
outputs. A sharp null or cancellation is
obtained when the balance control is
Each speaker line is fused with a 3 ampere fuse. In addition, thermostatic
circuit breakers, mounted to the output
transistors, open the power line circuit
in case of overheating. The circuit
breakers are self -resetting, once the
heat is dissipated. A view of the "insides" is shown in Fig. 4.
view, is the absence of the very popular
headphone jack. It's not as if AR's engineers forgot about it. They take the
While the controls enumerated earlier are generally self-explanatory,
there is one setting of the "mode"
switch, called "NULL," that requires a
word of explanation. We saw this feature on an early brand of stereo ampli-
o 00
N e °o0
O 01-
v °00
0 00
Fig. 6 -Power bandwidth for 0.5°/o THD, referenced to 60 watts/
channel (10 watts higher than the manufacturer's rating).
then properly adjusted.
Though AR doesn't mention it, even
the tone control settings can be equalized (one channel with respect to the
other) by means of this feature, thus
insuring exact equality of gain and frequency response for both channels. Of
course, the feature is useless if nonidentical loudspeakers are used in your
system, but it will still allow you to balance all signal input sources quickly
and precisely.
As mentioned earlier, the front panel
trades some flexibility for simple operation. We could liken the AR amplifier
to a sport's car, as compared to a family
car. For example, a loudness compensation control is omitted. True, AR
does mention the need for loudness
compensation at lower -than -live listening levels in its manual, and advises the
user to accomplish this compensation
by means of the accurately calibrated
tone controls. But it is certainly easier
to depress a loudness "on" -"off"
Fig 7 (left photo) -Tone -burst response of
AR amplifier at 1 kHz, 50°/o duty cycle.
Fig. 8 (right photo) -Square -wave response
at 15 kHz.
42 kHz
13 Hz
The most serious omission, in our
trouble to include a full -page brochure
explaining how to hook up a set of
stereo headphones. They even give a
diagram on how to wire up an adapter
so that one can switch from headphones
to speaker and back again. But with
stereo headphones being so popular
today, why inconvenience users who
choose to use them? Some minor omissions include absence of high and low
frequency cut filters, and a power on off switch divorced from volume controls.
We actually checked our calibrated
resistors and meters before accepting
the power readings of this amplifier.
With an 8 -ohm load, and with both
channels driven, the output had to be
cranked up to 601/2 watts rms per channel (bettering by far the 50 claimed)
before we reached the 0.5% total harmonic distortion (THD) figure. Amazingly, with a 4 -ohm load, power output
actually reached 90 watts rms per
channel for 0.5% THD. The curves of
Figs. 5 (IM and harmonic distortion)
and 6 (power bandwidth) tell the full,
incredible story of conservatism in
power ratings. Frequency response, too,
is better than claimed, measuring ± 1
dB from 15 Hz to 40 kHz. In short,
every single measurement (including
signal-to-noise, which was 62 dB and
78 dB for phono and high level inputs,
respectively) exceeded published specifications, often by a very wide margin.
Listening Tests
Connecting high -quality, "acoustic
suspension," low -efficiency speakers to
the AR amplifier, FM, prerecorded
tapes and discs were played. At no
setting of the volume control could the
slightest trace of distortion be detected,
excepting, of course, when speaker
cones began to travel beyond limits for
which they were designed. A scope connected across the output terminals of
APRIL 1968
one channel and calibrated to read
peak watts disclosed that the absolutely
clean sound filling the room reached
electrical outputs of 75 watts.
Performance quality was limited
only by components external to the
amplifier: loudspeaker systems and
signal sources. The amplifier imparted
no muddiness whatsoever. Attack time
was minimal and precise (see tone
bursts, Fig. 7, and square -wave response, Fig. 8). No amount of loud listening could induce the least bit of
"fatigue"-a subtle measure of an amplifier's distortionless qualities. This
will doubtlessly induce owners to play
music "loud," thus obviating the need
for tonal adjustments to compensate
for the Fletcher-Munson effect at low
listening levels.
In summary, let the prospective purchaser beware! If you plan to purchase
the AR amplifier, you had best look to
your loudspeaker systems and signal
sources such as tuner, cartridge, turntable, and tape machine. The AR stereo
amplifier will reveal many deficiencies
in allied equipment that are hidden by
lesser-quality amplifiers. For example,
what was thought to be some form of
low -frequency instability during quiet
musical passages turned out to be a
fair amoúnt of low -frequency rumble
(doubled and tripled by the loudspeakers, making it audible) emanating
from our highly respected turntable.
To combat this deficiency in auxiliary
equipment, an `outboard" rumble filter
with a cut-off frequency of about 30 Hz
was installed. From that point on, nothing marred flawless reproduction. The
variable cross -over tone controls enabled us to properly equalize some
older recordings (pre-RIAA) which we
prize for their dynamic range and recording quality.
In our estimation, the AR stereo integrated amplifier has no peer in its
price category insofar as performance
is concerned. And it outperforms most
units of its type that cost much more
than it does. The only area where it
falls down is in providing operating
frills such as a stereo headphone jack,
a rumble filter, and a loudness control,
among others. The need for these can
be circumvented, of course, but it would
be a minor nuisance to do so. This is an
insignificant deterrent to one who
wishes to own a magnificant piece of
equipment, however. For where else
can you get an integrated amplifier at
$225 that could flaunt 150 watts of
music power (if AR wanted to use
music power ratings instead of rms
power ratings) with such immaculate
amplifying ability? At this writing, AR
has wrapped up this class for them-
Garrard Synchro-Lab 95
Automatic Turntable
The Garrard line of automatic turntables over the past few years has employed the Volkswagen philosophy of
incorporating advances into its machines without changing physical appearances (or model numbers, in this
instance). However, there comes a time
when the improvements-and the requirements-outgrow the earlier models, and a new unit is born.
Such is the case with the SL -95, the
current Garrard "top -of -the -line" unit.
Mounted in the usual fashion on a
stamped steel base plate measuring
12% x 14 in. and supported on four
damped spring mounts, the unit is
literally full of innovations.
To begin with, a new "Synchro-Lab"
motor is used to maintain a constant
speed over a wide range of line voltages, and yet still have sufficient power
to insure a fast start when first turned
on. The motor is a combination of an
induction motor-such as are used in
most turntables-and a synchronous
section. While a large synchronous
motor can serve satisfactorily for both
starting and running, this is an uneconomical solution, since the synchronous
motor is expensive to build, and if it is
to have sufficient power, it becomes relatively heavy. By combining the two
sections, sufficient starting torque is
provided, and in addition the advantages of the synchronous motor are retained. These advantages are quite well
known, but to the novice, there is no
harm in restating them. This type of
motor has the advantage of running at
a speed which is entirely dependent on
the frequency of the line power rather
than on the voltage of the supply. In
many localities there is likely to be a
variation in the line voltage during the
day, yet all-or nearly all-domestic
electric power is maintained at an exact frequency of 60 Hz/sec so that
electric clocks, which use small synchronous motors, will keep exact time.
Fig. 2-Closeup of tone arm shows adjustable sliding counterweight (rear of tone
arm), calibrated stylus -force gauge (circular dial underneath tone arm) and anti skating control (foreground).
Fig. 1-Garrard's top -of-the -line SL -95.
"automatic transcription turntable"
Old timers will remember the Crocker -Wheeler motor which was used in
early motion picture theatres in the
Western Electric 208A Non -Synchronous Reproducer Sets to provide sound
during intermissions or whenever
sound was being presented to the audience without originating on the sound
track of the film itself or from a synchronized Vitaphone record. These Reproducer Sets consisted of a heavy-
35-pound-turntable/motor which used
an induction disc section to bring the
turntable up to speed and a synchronous section to hold the speed to the desider 78.26 rpm. These motors were
superb for their purpose, and many an
early hi-fi buff secured one of them for
his record playing facility. They did
have one disadvantage for those daysthey had a strong hum field which practically ruled out magnetic pickups.
Garrard has adopted a similar arrangement for the SL -95 motor (which
is also used on the SL -75, SL -65, and
SL -55) and it performs just as well as
claimed. Over a voltage range from our
available 140 down to 35, the turntable
speed remained constant, and while
playing a piano record, we varied the
line voltage from maximum down to 35
volts with nary a wow. This is an important consideration in the choice of
a turntable.
The drive method consists of a
stepped motor pulley and an idler.
Another feature is the tone arm and
its miscellaneous advantages. In the
Fig. 3-Garrard's record platform rises into
position for automatic play when the button next to it is pressed. The platform
is retracted out of the way for convenient
manual use.
Check Reader Service No. 54
APRIL 1968
- Combined
manual -cueing -pause
shown at left; automatic control
lever at right.
Fig. 4-Combined speed and record -size
selector. (The SL -95 has 331/3 rpm, 45 rpm
and 78 rpm speeds.)
first place, it is constructed of a combination of a low -resonance woodafrormosia, they call it-and an aluminum frame. It is light, and without apparent resonance in the audible
spectrum. The head is integral with the
arm, and the cartridge is mounted on a
slide which slips into the head readily.
The counterbalance permits the use of
cartridges ranging in weight from 0 to
22 grams
yes, the arm will balance
with no cartridge installed-which covers the entire current range of cartridge
weights which extends from 1.5 to 18.5
grams. The stylus force is adjustable by
a small dial on the underside of the
arm from 0 to 51/2 grams. (See Fig. 2).
This dial is calibrated in 1/2 -gram divisions, and further provided with 1/4 gram click stops. At the left of the arm
pivot is a record platform which is used
for automatic playing. The platform
can be depressed for manual playing
simply by pressing down on its top; it
rises by depressing a white button adjacent to the base of the platform.
Anti -skating correction is provided
by a small arm which carries a sliding
weight over a calibrated scale. The arm
records, but this is of little importance
since the 10 -in. record is now a rarity,
and the absence of the interchangeable
automatic play should be missed only
by the rare individual who has a large
collection which contains many records
of both diameters. It will also be noted
that the SL -95 does not operate at 16%
rpm, but few users have them anyhow.
The operating controls are centered
at the right front of the base plate, and
consist of two selector levers similar in
appearance to the speed/diameter selector. One lever is for automatic operation, and starts, rejects, and stops the
automatic operation. The other lever is
for manual operation, and has three
positions-PLAY, LIFT, and STOP. When
the lever is thrown to LIFT, the arm
rises and remains up until the lever is
returned to the PLAY position, when the
arm lowers to a position about four
grooves ahead of where it lifted, thus
replaying a few seconds of the record.
The STOP position returns the arm to
its rest and stops the motor, with the
idler retracted from the motor pulley.
A small lever at the base of the arm
rest serves to lock the arm to the post.
The usual locking screws are provided
to hold the unit solidly against the
motor board while the turntable is being transported.
The turntable mat is provided with
grooves at the three set -down positions
so that in case the arm is lowered to the
turntable when no record is there, the
stylus simply rides in the grooves,
rather then being thrown off the platter
and possibly damaging the stylus.
The turntable platter is of stamped
aluminum, and is relatively "dead" so
as to transmit no resonances to the
stylus. It is composed of two separate
sections, with the inner one serving as
the driven surface which is contacted
by the idler.
The platter consists of two "pans"
which are attached to a die-cast center
section which contains the actuating
pinion gear. The outside diameter is
12 in., and the inner driven pan is 101/4"
in diameter. This is the rim which is
driven by the idler wheel making simultaneous contact between the motor
pulley and the rim of the inner "pan."
The entire platter assembly weighs 31/4
lbs. The reason for the double -pan construction is that the visible portion is
6-Dual platter construction is illustrated, with a 12 -in. aluminum turntable
platter and a 101/4 -in. drive section. The
entire platter assembly weighs 31/4 lbs.
rises as the arm moves toward the
center of the record, thus compensating for the lesser amount of correction
needed toward the center of the disc.
This type of anti-skating compensation
maintains a fairly correct force because
of the reduction of the length of the
lever arm as the arm moves across the
record. At the outside where the most
correction is needed, the lever arm is
longest. At the center, it is shortest, as
it should be to reduce the amount of
corrective force applied.
The SL -95 operates at three speeds,
and the speed and record diameter are
set by a single selector lever. This lever
is set at one of five positions -12 -in. 78,
7 -in. 45, and 12-, 10-, and 7-in. 33%.
Thus it will not intermix 12- and 10 -in.
outside the base plate, whereas the
deeper section of the driven pan provides for the up and down movement of
the idler wheel.
A base is available as an accessory
when the unit is to be used on a table or
shelf. This base is a molded plastic
simulating ebony and walnut, with silver trim. Another similar unit is available with a lighted rocker switch
mounted on the front apron to permit
"Power-Matic" operation so as to turn
off the entire system when the last
record is finished. Both bases are also
available with molded accessory trays
which accommodate both long and
short spindles and the 45 adapter. The
cover keeps the accessories dust-free,
yet immediately accessible.
The automatic spindle permits handling six records automatically, with
gentle changing. The single -play
spindle is in two parts-the upper section rotates with the record.
Measured cycling time for the SL -95
shows that set-down occurs 10 sec. after
actuating the start lever, and that record changing takes only 14 sec. from
the last note on one record to the
first note on the next. This is relatively
fast for 33% records, but is exceeded
at 45 by only three seconds, and by five
at 78 rpm. At this higher speed, the
arm action is rather abrupt, and the
stylus is apt to bounce once or twice on
set -down.
Tone arm resonance is below 10 Hz.
Tracking error does not exceed 1.5%
at maximum and minimum diameters.
Changing is initiated by the run-in
groove, and is effective down to stylus
forces as low as 1/2 gram. Suitable operation is obtained with stylus forces of
as low as 1 gram (using a Shure V-15
cartridge) although for optimum performance, a force of 11/2 gms. is recommended.
Rumble was measured at 32 dB below 3.54 cm/sec on stereo, and 36 dB
below on mono, with the principal energy content in the vicinity of 3 Hz,
which corresponds to the rotational
speed of the idler, which is approximately 170 rpm. Wow and flutter were
between 0.20 and 0.25 per cent, all occurring in the frequency range from 0.5
to 6 Hz, since the range from 6 to 500
Hz showed practically no flutter at all.
In all, the performance is quite acceptable for any but truly professional
studio equipment. The SL -95 is priced
at $129.95, and the co-ordinated base at
$5.95. The Power-Matic base is $15.95
with the accessory tray, $14.95 without.
A dust cover of clear styrene is available at $5.95.
Check No. 57 on Reader Service Card
APRIL 1968
37te cw.9-teia,th Wo/nv
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«electronic suspension»
Loudspeaker Systems
frituii w
Avveuie Jeeddach
eouaalie bvilikArt
tun 4i6ciahe
6'J05 ogeóóaffluine
e16adc/Ft , 3;xam 77036
APRIL 1968
Check No. 59 on Reader Service Card
3 -Way
Columnar Loudspeaker System
T. Bozak, The R. T. Bozak
34e ConventIon
Chairman: Paul Kruttschmidt
Capitol Records
A 150 -mil Slave Transport
Place: Hollywood Roosevelt Hotel, Los Angeles, Calif.
Date: April 29 (Monday) through May 2 (Thursday)
Technical Sessions: 9:30 a.m., 1:30 p.m., 7:30 p.m.
(no 7:30 p.m. session on May 1)
Equipment Exhibition: April 20 -April 30: 1:00 p.m. -9:00 p.m.
May 1: 1:00 p.m. -5:00 p.m. May 2: 1:00 p.m. -5:00 p.m.
Awards Banquet: May 1, 7:30 p.m.
To be presented at
Technical Sessions
For readers unable to attend, reprints of
following papers are available (50e ea.,
AES members; 85¢ ea.
from Audio Engineering Society, Inc.,
Room 428, The Lincoln Building, 60 E.
42nd St., New York, N. Y. 10017
Chairman: James F. Kane
Motorola Semiconductor
Temperature Characteristics
John C. Sinclair, Zenith Radio Corp.
A Self -Contained Condenser Microphone
Using a Solid -Electrolyte Battery for Perma-
nent Polarization
Alan Dauger and Charles F. Swisher, Vega
Electronics Corporation
The "BI-FET" and Its Circuit Application.
David R. Pryce, Amperex Electronics Corp.
The Audio Behavior of Integrated MOS Devices.
Kane, Motorola, Inc.
Chairman: Jim Noble
Altec Lansing
Frequency Controlled AGC in Small -signal
Audio Amplifiers
Wm. Greenbaum and Ira) Gharib, Zenith
Radio, Hearing Aid Div.
New Solid -State Amplifier for the Recording
Vern Bushway, RCA West Coast Operations
Modular Transistorized Volume -limiting Am-
Walton N. Hershfield, Nelson -Hershfield
Donald Kahn, 3M Company
Mass Production of Prerecorded Tapes
Tom Everett, Ampex Corp.
Design Considerations and Objectives in the
Design and Development of an Automated
Stereo Cassette Changer and a Compact
Stereo Cassette Playback Unit
Edward R. Hansen, North American
Philips Co., Inc.
The Newell Principle in Tape Cartridge Systems
C. W. Newell, Newell Industries
High -Speed 0.150" Tape Duplication System
R. Millward, Ampex Special Products Department
Don Richter, Melcor Electronics Corp.
Amplifier with an FET Compression Circuit
David L. Campbell, Fairchild Semiconductor, Inc.
Modern Music-Rock, Jazz, Pop-and the Amplifier Designer's Dilemma
Paul B. Spranger, Altec Lansing
Chairman: Charles Pruzansky
RCA Victor Record Division
A Low -noise
Operational Amplifier Applications for
Audio Systems
B. S. Osmondy, Opamp Labs
A Highly Refined Lamp -photocell Automatic
Level Control Device Having Fast Attack
Time, Instantaneous Transient Release, and
Low Distortion
William Ross Aiken, Vega Electronics
Chairman : George Augspurger
James B. Lansing Sound, Inc.
Dragon-A Pyroacoustic Transducer
James S. Arnold and Vincent Salmon,
Stanford Research Institute.
Speaker System Design Using a Reverberation Chamber
Victor Brociner, H. H. Scott, Inc.
Frequency -Modulation Distortion in Loudspeakers
Paul W. Klipsch, Klipsch & Associates
Recent Speaker System Developments to
Meet the Dynamic and Power Requirements
of Amplified Musical Instruments
Will Hayes, Altec Lansing
Methods of Rating Power Capacity of Cone type Loudspeakers
Bart N. Locanthi, James B. Lansing Sound,
Long -Time Sensitivity of Foil -Electret Microphones
G. M. Sessler and J. E. West, Bell Tele-
phone Laboratories
Electret Condenser Microphones of High
Quality and Reliability
Dr. Preston W. Murphy, Thermo Electron
for Cassette Dup-
Applications of the Audio Operational Am-
plifier to Studio
The Scanning Electron Microscope-A New
Tool in Disc -Recording Research
J. G. Woodward, RCA Laboratories
Splicing Tapes and Their Proper Application
Delos A. Filers, 3M Company
Polyester and Acetate as Magnetic Tape
Delos A. Filers, 3M Company
An Improved, Low -crosstalk Recording Head
Designed for Sync Playback
Warren B. Dace, Lipps, Inc.
Remote Control of the Overdub or Sync Operation of a Multi -channel Recorder
Dale Manquen, 3M Company
New Compact Electronics for the 3M Brand
Professional Audio Recorder
Dale Manquen, 3M Company
Precision Alignment and Quality -Control
Techniques for Many-Channel Recorders
Operating at Short Wavelengths
Keith O. Johnson, Gauss Electrophysics,
Synchronous Sound for Motion Pictures
Ronald E. Cogswell, Ryder Magnetic Sales
"How -To" Review of Disc Recording Prac-
tives-Stereo and Mono
Temmer, Gotham Audio Cor-
Chairman: Rolf
DuKane Corp.
Professional Quality Sound Systems for
School Auditoriums
W. R. Torn, DuKane Corp.
Trends in Sound Reproduction Research
Dr. Henry F. Olson, RCA Laboratories
'/'-Octave Filter Set for Equalization of
Sound Reinforcement Systems
Don Davis, Altec Lansing
Mfg. Co.
APRIL 1968
The Dolby System gives
10dB increase in
usable dynamic range
A 10-15dB hiss reduction
A 10dB print -through and
cross -talk reduction
A 10dB hum reduction
PLUS generally cleaner, more
transparent recordings-with
unaltered frequency response
and signal dynamics.
Recording engineers and musical directors are
so enthusiastic about the Dolby S/N Stretcher
system that the network of users is growing at
an astonishing rate-on an international scale.
Master tapes made with the system now fly
regularly between the major recording centers of
the world, such as New York, London, Rome,
and Vienna.
The basic principle of the system is simple.
Low-level signals are amplified in four independent frequency bands during recording and
attenuated in a complementary way during playback-recording noises being reduced in the
process. High-level signals are unaffected by
this procedure (no distortion or overshooting),
and the symmetrical design of the circuitry
ensures that the signal is restored exactly in all
details-high-level and low-level, amplitudes and
phases. The result is a noise reduction system
with ideal characteristics-perfect signal handling
capability which can pass any line -in, line-out
A -B test, and a genuine 10dB noise reduction.
In short, the Dolby system offers an entirely
new area of sound for the recording engineer.
Get to know more about it fast by writing directly
to Dolby Laboratories or contacting your nearest
(212) 243-2525
NEW YORK N.Y. 10014
Cables: Dolbylabs New York
U.K.: Dolby Laboratories, 590 Wandsworth Road, London, S.W.8.
Europe and the Middle East: Impetus SA, 2 Via Berna, Lugano,
Switzerland. Australia: General Electronic Services Pty. Ltd., 5
Ridge Street, North Sydney. Japan: Sakata Shokai Ltd., No. 10,
2-Chome, Kandakaji-Cho, Chiyoda-Ku, Tokyo. South Africa: Vita phone Pty. Ltd., Cape York, Jeppe & Nugget Sts., Johannesburg.
Check No.
61 on
Reader Service Card
One-third Octave Universal Frequency
New Methods for Evaluating the Effectiveness
of Sound Amplification Systems in Reverber-
Response Shaper
Bernard Katz,
ant Spaces
Jacek Figwer, Bolt Beranek & Newman
Audio and Acoustical Instrumentation as
Used by a Sound Contractor
Carl Colip, Jr., Commercial Electronics,
The Effects of Detailed Equalization on Contemporary Sound Reinforcement System
Don Davis, Altec Lansing
Sound Reinforcement Systems for the New
York Philharmonic and the Metropolitan
Christopher Jaffe, Christopher Jaffe &
Associates, Inc.
Richard Burden,
Snow, Bissett-Berman Corp.
Knopoff, Institute of Ethnomusicology,
University of California
Spectra Sonics
A High -Performance Control Console with
Allan P. Smith, Naval Training Device
Active Isolation "Transformers" in Studio
Console Design
Wm. G. Dilley, Spectra Sonics
The Design of a State -of -the -Art Recording
Console for the Chicago Symphony Orchestra
Dr. Ing, W. T. Kapuskar, Research & De-
The Relevance of Musical Theory to Musical
Data Processing
Michael Kassler
The Stanford System
David Poole and John Chowning, Artificial Intelligence Project, Stanford University
Music Signal Processing for Fun and Profit
Robert A. Moog, R. A. Moog Co.
Chairman : Keith O. Johnson
Gauss Electrophysics, Inc.
of Nevada
A Functional Audio Control System That
Meets the Professional Engineer's Responsi-
bility to the Industry
Hardy Martin, Sambo Sound Studios
for On-line Generation
of Sound by Computer
Console Design from the Operating Engineer's Point of View
Billy R. Porter, United Recording Corp.
velopment, Hewlett. Packard, GmbH.
An Algorithm for Segmentation of Connected Speech
D. R. Reddy and P. J. Vicens, Computer
Science Department, Stanford University
A Symbolic Approach to Musical Composi-
Versatile Audio Control Console
Donald McLaughlin, Electrodyne Corpor-
Chairman : A. E. Byers
United Recording Corp.
Solid-state Condenser Measuring
phone Assembly
Sound Production in Wind Instruments
John Backus, Univ. of Southern California
Preprocessing of Speech for Added Intelligibility in High Ambient Noise
Ian B. Thomas & Russell Niederjohn, University of Massachusetts
Richard Burden Associ-
Art Soff el
Statistics of Delayed Reflections
Michael Rettinger
Reverberation Measurement by the Automatic Decay -Rate Meter and other Methods
F. K. Harvey, Bell Telephone Laboratories
Instant Recording Studios using Prefabricated Acoustical Panels
Allan P. Smith, Naval Training Devices
Image Fusion Requirement of the (Haas)
Precedence Effect
Mark B. Gardner, Bell Telephone Laboratories
Noise Rating and Hearing Impairment
Aram Glorig, M.D., Callier Hearing &
Speech Center
Some Effects of Interference on Speech In-
Foster, CBS Laboratories
The Need to Hear Ourselves as Others Hear
LTV Research Center
Dependant Characteristics of
Cornet, Oboe, and Flute Tones
James W. Beauchamp, University of Illinois, Dept. of Electrical Engineering
Some Time
Methodology for Acoustical Data Gathering
Benjamin B. Bauer, Bert A. Bodenheimer,
Chairman : M. V. Matthews
Bell Telephone Laboratories, Inc.
Transmission Measuring Sets
Arthur C. Davis, Altec Lansing
High -Speed Automated Test System
Daniel A. Roberts, Gates Radio Co.
and Edward
& K Instruments
Improved Performance Capabilities of Wireless Microphones
Swisher, Vega Electronics Cor-
Two-inch and 16- and 24 -track Master Recorders
Harshberger, Ampex Special Products
Mobile Etectroacoustic Laboratory
Allan P. Smith, Naval Training
Random Access Audio Systems
M. Kuljian, Ampex Special Products Dept.
Booth Numbers
Blossom Room
North American Philips Co., Inc
Fairchild Recording Equipment Corporation
Sennheiser Electronic Corporation (N. Y.)
Shure Brothers, Inc.
Melcor Electronics Corporation
Taber Manufacturing and Engineering Co.
Gauss Electrophysics, Inc
9, 10 & 11
Altec Lansing
Dolby Laboratories, Inc.
13 & 14
B & K Instruments
The R. T. Bozak Manufacturing Co.
Electrodyne Corporation
Vega Electronics Corporation
19 & 20
Universal Audio
21 & 22
Gotham Audio Corporation
Booth Numbers
Spectra Sonics
Magnetic Recorders
26, 27 & 28
Scully Recording Instruments Corp.
29 & 30
Langevin, Div. of Scientific Industries
East-West Room
General Radio
McMartin Industries
3M Company
34 & 35
36, 37 & 38
Harvey Radio Company, Inc.
R. A. Moog Inc.
Mezzanine Private Demonstration Rooms
Boulevard Room
Electro -Voice, Inc.
Ampex Corporation
Room C
Dolby Laboratories, Inc.
Room H
APRIL 1968
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APRIL 1968
the A
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Check No. 63 on Reader Service Card
Stravinsky Conducts Symphony in E Flat,
Op. 1. Columbia Symphony Orch.
Columbia MS 6989 stereo
A superb parlor -game record here.
Classical Record Reviews
Stravinsky Harvest
Stravinsky: Firebird Suite. Tchaikowsky:
Marche Slave; Mussorgsky: Night on a
Bald Mountain. London Symphony Orchestra, Stokowski.
London SPC 21026 stereo
Got to keep our eyes on these Stokowski Phase 4 spectaculars. In a sense
they're corny, and the music is hardly
chosen for the highbrow taste. (Not as
of 1968, anyhow, though some of this
music was very far out in its early
days.) But we can almost always expect
something special from the old Maestro, who has been jolting musical listeners out of a million-odd seats ever
since 1912.
In this collection of chestnuts the
radioactive item is "Night on a Bald
Mountain," as revised by none other
than Leopold Stokowski. In true modern style he says that, in Russia, soon
after the Revolution, "the authorities
permitted me to photograph the original score, which I have in my library."
("This after he has just told us there
were four different unfinished versions.) Aha, the old musicologist! But
no. "The version we have performed is
based on the Original of Moussorgsky
with certain changes and additions of
Rimsky-Korsakov." Then he adds, casually, "I have re -orchestrated the whole
composition because of passages which
were out of balance and therefore unclear." Some musicology!
If you think you know the "Night,"
then you'd better try here. Stokowski's
version of it is a terrific spectacular
and, indeed, it does seem to bring out
a great deal of the chiller-diller horror
that has been missing at least since
those four original uncompleted versions. A tour de force for every hi-fi set,
and a musical revaluation, too.
Nor is the tired old "Marche Slave"
tired here. I haven't ever enjoyed it as
much before. Instead of the usual
heavy, ponderous doom -like sound, this
performance breezes along with the
freshness of a Sousa march, or perhaps
a ballet of very lively elephants. Lovely.
Only the "Firebird" Suite seems
somewhat tired. It has been a Stokowski set piece for too many years, I
guess. His version still, somehow, manages to make it into a ripe old Romantic piece, where many later conductors
stress its modern overtones.
Phase 4 is spectacular but not, in
these days, unusual. Rather beefed-up
bass, I would say, at least via our RIAA
playback. Probably intentional.
Try it on your musically simpleminded friends! They'll think it is
Tchaikowsky or Rimsky-K., or any one
of a dozen others of that period. It is
one of the composer's very earliest extant works and lots of fun to hear today. It's done here with just enough
wit and indulgence, by the old man
himself, to point up both the youthful
bombast of the music and the undeniable genius of the very young composer
who wrote it-1905-07.
The Columbia styling of the long continued Stravinsky - by - Stravinsky
series is remarkably consistent in sound
and engineering; though dates range
over quite a spell, the time fàctor is not
unduly important, beyond the major
breaks occasioned by LP, then stereo.
This would seem to be a relatively
brand-new tape.
Sound: B+
Stravinsky: L'Histoire du Soldat. Complete,
in French and English versions. Made-
to B-
Sound: B
Stravinsky Conducts Four Great Ballets
(Apollo, The Fairy's Kiss, Pulcinella, Orpheus). Columbia, Chicago Symphony
Orchestras, vocal soloists.
Columbia D3S 761
Time was when we knew only the
early Stravinsky ballet scores-"Fire
Bird," "Petrouchka." These middle
and late scores are now easy on almost
any ear, no longer sounding very "modern"-and they are composer -authentic
performances out of Columbia's vast
collection, helpfully assembled in this
big album.
All the recordings date from recent
years, done in stereo of Columbia's
moderately elaborate sort. Most of us
will find it highly satisfactory for this
music, with more of a close-up stage
sound than a so-called concert -hall
effect. Why not? It isn't concert music,
after all. Music for the ballet theatre,
which is something else again.
Occasional vocal soloists appear in
these complete versions; Stravinsky has
often used them in his stage -type
Performance: A
Sound: B -1 -
Milhaud, Jean-Pierre Aumont,
Martial Singher; Instr. Ens. conducted
by Stokowski.
Vanguard VSD 711/6 (2) stereo
This album brought a number of interesting innovations, both artistically
and technically. It is, first, a high -leveltype performance with major imported
stars for the speaking parts and the direction. And it is done twice-a version
in the original French (spoken, against
the music) and in a translation into
English. In addition, this was one of the
first major "Dolby-ized" releases in the
U. S. and it shows, in ultra -smooth,
quiet -background sound.
Presumably, simple tape work put
the two languages, each on its own LP,
against an identical musical performance. The speakers are, of course,
French in their native language and
that version is decidedly the best. Aesthetic uniformity and consistency made
it reasonable to do the English with the
same speakers; but their accents are
very decided, though the English is perfectly intelligible. And on its own the
English version is best as a sort of audible translation of the French. Not a
bad idea, come to think of it.
Performance: A
Check No. 65 on Reader Service Card
The turntable everyone else is still trying to make.
You've undoubtedly noticed what appear to be Dual features cropping up in other
automatics. Features like cue controls, continuously variable anti-skating adjustments and ro-
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And other automatics seem to be
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because we know something the others are rapidly finding out
It's harder than it looks to make a Dual.
United Audio Products, Inc., 535 Madison Avenue, NewYork, N.Y.10022.
Classical Record Reviews
Mozart Festival
Mozart In London (The Odyssey of the
Young Mozart-Vol. I). Frankfurt Ch.
Orch., Koppenburg; Karl Engel, pf.
Odyssey 32 16 0164 stereo
The start of an interesting series on
Columbia's budget label, musically outlining the famous virtuoso journeys of
the child prodigy Mozart, beginning
here at the age of eight, with the composer's only trip to London.
What music-at eight? Plenty. The
most profound influence on the small
child was J. S. Bach's youngest son,
Johann Christian, often called "the
London Bach" (and at this point, in
1764, already well into middle age),
The small -boy Mozart worshipped him,
and met him as a musical equal, too.
On this record we have first a typical
J. C. Bach work, a Sinfonia in B flatall airy fluff and expert musical "business." Then a parallel piece, a Sinfonia
by Mozart! At eight, he wrote it in London to keep himself busy when Papa,
being sick, wouldn't let him practice out
loud at the keyboard. Astonishing.
Side 2 gives us two of the often mentioned but rarely -heard early
"Mozart" piano concerti, which were,
at age 15, Mozart's very ingeniously
contrived arrangements, for his own
use, of a number of keyboard sonatas
by his friend and mentor, Bach. They
are strictly portable concerti, set for the
absolute minimum force of musicians
likely to be available in small provincial
towns (three-with Mozart at the keyboard).
Of course, given larger available
forces, they could be nicely filled out,
as they are in this performance.
Odyssey's European orchestra is sincere and musical, if not always very
precise. Karl Engel's piano is rather too
large and too close for this music,
notably in the first little concerto on
Side 2. Unaccountably, it sounds better
in the second concerto.
Performance: B
Sound: B
Mozart: Don Giovanni. Nilsson, Arroyo,
Grist, Fischer-Dieskau, Plagello, Talvela,
Schreier, Mariotti, Czech Choir of
Prague, Czech Nat. Theatre Orch.,
Deutsche Grammophon 139260/63 (4)
What a sound! I had not got around
to a big Mozart opera on records for
some time when I got to this one, and
what D -G has done here in stereo terms
is enough to make your hair stand on
I would say that the sheer sound on
these eight sides, in terms of stereo
spread and space, of clarity and brilliance, immediacy and, above all, in
dynamic range, beats any sound I have
yet heard-though I assume D -G has
the same on tap for many another recording.
Especially, the dynamic range is
astonishing. You'll notice it the instant
you put down the stylus for the commanding tones of the overture-the
velvet silence that accompanies the soft
passages (which, of course, you will
turn up higher, without thinking) then
the sudden, unbelievable impact of the
loud tones, so much louder than you
expect. Quite fantastic, Dolby or no
D -G, unlike some other producers of
opera in stereo, does not feel inclined
to place its voices back Sways, in the
orchestra, as per actual stage opera. (In
some recordings they almost disappear
at times.) Here, they are very much up
front and very potent. Impressive
sounds, all right, and never a trace of
distortion, no matter how huge the
vocal power. But in a way this becomes
frustrating-for the orchestral sound is
so splendid that you want to hear it
loud too; and when you turn it up, the
voices blow you out of your seat. Can't
have both. So you settle for the right
vocal volume and let the orchestra find
its place as a proper accompaniment.
(In the end, this is musically right, in
spite of all temptations to higher wattage.)
The international -type performance,
recorded in Prague where the opera
was first heard 180 years ago, is first
rate, but I'd say not quite tops. There
are wonderful voices here, every one of
them musical and accurate. But they
are very big. To an extent, the singing
is uneconomical for such a taut, sophisticated drama, with so many subtle
overtones of tragedy, cynicism and
humor. Too much gorgeous singing, not
quite enough musical acting for the
proper lightning -fast contrasts and
rapid-fire action.
Surprise! The famed Wagnerian
singer Birgit Nilsson is the best of them
all here as the much -wronged Donna
Anna. Wouldn't have believed it. The
others are good, but not ideal. Even
Dietrich Fischer-Dieskau, finest baritone around today, isn't really the type
for the devilishly amoral Don. Too serious, too sincere. (If you want to see
what I mean, try the all-time top recording, the pre-war Glyndebourne
production with John Brownlee.) But
even so, it is a pleasure just to listen
to these superb vocal instruments, in so
fine a recording.
Sound: A
Performance: B
APRIL 1968
Mozart: Serenade for 13 Wind Instruments, K. 361. Musica Aeterna Wind
Ensemble, Waldman.
Decca DL 710150 stereo
I'll stick my neck out. This is one of
the finest records, in its category, to
come out of New York city in many
years, in an all-around sense-both
musically and technically.
In the international music market,
New York is relatively provincial. We
think we're pretty good, of course; but
who else does? In most musical areas,
New York either benefits from visiting
firemen, the great performers of other
places, or puts on second-best versions
on its own steam. This-of coursereferring to "classical" music; other
sorts thrive beautifully in NYC.
And so a man like Frederic Waldman, possessing all the sophistication of
a central European heritage, yet able
to lead those tough babies, the typical
New York professionals out of Local
802, able to inspire them straight out
of their habitual cynicism, is really
somebody. Frederic Waldman is such
a conductor.
The Mozart Serenade on this record
has often been played and recorded;
this is just about the best version I ever
hope to hear-and out of New York!
It is intense, dedicated, marvelously
well rehearsed and utterly expressive.
The spirit of the piece-a wind Serenade for thirteen instruments (not the
normal four or five) and, under its stylishly light exterior, a profoundly serious work is perfectly understood.
Moreover, the combined woodwind
sound (with two of those rare and interesting bass clarinets, the basset
horn) is recorded with absolutely superb quality. The ensemble is full and
round and impressive. Each of the
winds instruments seems positively to
breathe its own special woodwind quality, as well. An extraordinarily musical
hi-fi sound.
Performance: A
Sound: A
Mozart: Wind Serenade in E Flat, K. 375
(original version). J. Myslivecek: Two
Octets. Musica Viva Ensemble, Bolle.
Monitor MCS(C) 2126 stereo
Here is the relatively familiar
Mozart wind Serenade in E Flat in its
original form as a wind sextet, a first
recording. The usual version, revised,
is an octet with two added oboes, a
much richer texture for the music; but
the sextet version has interest on its
own, with the two clarinets doing
double the work, minus the oboes.
APRIL 1968
Here also, on Side 2, is a new "unknown" composer and a remarkably
fluent musician as well as friend of the
Mozart family. Josef Mysliveck was,
alas, saddled with an unpronounceable
Czech name, and he was a professional
miller, as well. But musical instincts
prevailed and he wrote some of the
most lucidly expressive music of the
time-short of Mozart himself and a
very few others. The two wind Octets
played here require much more virtuosity, in all the parts, than the Mozart
work, but the writing is so skillful (and
the playing) that the whole seems quite
Monitor's excellent home -based Collector's Series still plugs "compatible"
stereo, a slightly dead issue now that
everybody says his stereo is playable on
mono equipment. No matter
stereo sounds as good as any, compatible or no. The tapes are by the well versed David Hancock, New York
musician and solo recording engineer.
Sound: B+
Performance: A
Mozart: Symphonies No. 39 in E Flat, No.
41 in C ("Jupiter"). Japan Philharmonic,
Interesting Miscellany
Borodin: Symphony No. 2 in B Minor; On
the Steppes of Central Asia.
Tchaikowsky: Romeo and Juliet. Saxon
State Orch., Sanderling.
Heliodor HS 25061 stereo
This ought to be a real bargain-excellent sound, out of Deutsche Grammophon, and a brace of typical and
well known Russian works of the late
Romantic era. Alas, it isn't a bargain,
even at the low Heliodor price.
Why? The music, technically played
with accuracy, plods along didactically,
unimaginatively, without a spark. Just
notes-lots of them. The Borodin symphony, which is an absurd old war
horse at best, nevertheless can be impressive if done with the right swashbuckling drama. Here, it is unbeatably
dull. Dreadful Romeo and Juliet is
somewhat better but only because the
music is intrinsically more meaningful.
It's not a good version, considering the
manifold competition available.
Peter Magg.
Crossroads 22 16 0126 stereo
Two of the great last three symphonies of Mozart (straddling the wellknown G Minor, No. 40) in a curious
performance, Japanese but led by an
authentic Westerner. The styling is thus
outwardly correct, in a middle -European tradition; warm, somewhat heavy
and a lot less intense than comparable
U. S. performances, which tend to
"high voltage." But the Japanese-at
least to my ear-do not hear many important subtleties in the music. They
play accurately but, so to speak, musically deadpan. OK unless your ear
is better than theirs.
Crossroads began as an all -Czech
operation, via Epic and out of CBS but
sourced exclusively from the Czech
Supraphon label. But evidently Supraphon itself sometimes gets out of
Prague. Or was the Japanese orchestra
visiting there on tour? In these times,
anything can happen at least on
The recorded sound is a bit bottom heavy and seems very slightly distorted
in the louder parts. Equalization of
foreign -made tape is still a serious
problem for us. It's only too easy to
follow the rules-and yet come out with
a wrong sound.
Sound: B-
Performance: C
Brahms: Serenade No. 1 in D, Op. 11. The
Chamber Symphony of Philadelphia,
RCA Victor LSC 2976 stereo
This attractive recording of the ever lovely Brahms Serenade (one of two,
his first informal works for orchestra)
seems to have been a herald of things
to come; shortly after its release the
official announcement burst upon us
that the Philadelphia Orchestra was returning from Columbia to RCA Victor.
Connections between the members of
the big orchestra and this group are not
specified but, shall we say, are likely.
The only problems at all with this
recording are minor. The work, being
fairly new to the players (it isn't performed too often), is in spots a tiny
trace ragged in the ensemble. Not
much. And the RCA recording, also
perhaps newly arrived in Philadelphia,
seems a bit distant and not well filled
out acoustically. Very minor problems
in view of the fresh, natural quality of
the playing. The few recent recordings
of the work have been musically inferior. This is a piece that all who enjoy
Brahms should know well-it has been
a favorite of mine since I bought part
of it on an ancient 78 rpm disc as a very
youthful collector.
Sound: B
Charles Ives Orchestral Works. (Robert
Browning Overture, Circus Band March,
Set for Theatre Orchestra, The Unanswered Question.) Royal Philharmonic
Orchestra, Farberman.
Vanguard Cardinal VCS 10013 stereo
Charles Ives, America's rugged musical pioneer of the early part of this
century, is at his most piquant for most
modérn ears in these orchestral works.
(The vocal music and the piano and
chamber works are more difficult, decidedly.) They remain outrageous in
sound, provocative, howlingly dissonant, and yet old fashioned and
highly American in a smalltown wayyou can't help liking them. For beneath
the deliberate shock, the clashings of
three or four harmonies all at once, are
gentle old hymn tunes, Fourth -of -July style band music, unassuming stuff that
is the essence of non -highbrow art.
The famed British orchestra would
perhaps make its former chief operator,
Sir Thomas Beecham, turn purple with
astonishment, playing this music-but
the orchestra plays it very well, with
both accuracy and an appropriate reverence. Papa Ives, at last, is internationally recognized.
Vanguard's Cardinal recordings, like
the Nonesuch Elektra series called
Checkmate, are new original recordings, not reissues, and are priced a dollar above the low-priced level, still well
below the "standard" expensive labels.
Let's hope Vanguard is able to prosper
in this venture; it is of a sort that fills
a needed gap, between high-priced originals and low-priced reissues.
Performance: B+
There are unusual late Liszt works
here, the gloomy and powerful Hungarian Portraits (of heroes out of the
revolutions of 1848) and the strange
little "Lost Waltzes." Only the Polonaises are of earlier and more conventional sound, though lovely enough on
their own.
Edith Fernadi is one of those determined and hard-working pianists who
do us immeasurable good simply by
performing music that ought to be
played. But there is a somewhat chilly
impact in her otherwise impeccable
finger work. Somehow, she does not feel
the inner depths, only the outer. Not
bad-just not tops in musical communication. She plays the notes with a
great deal of power, which is enough to
get their sense over to any ear.
Sound: B
Prokofieff: Symphony No. 4, Op. 47/112
(revised version). Moscow Radio Sym-
phony Orch., Rozhdestvensky.
40040 stereo
The original Fourth was composed
for the 50th anniversary of the Boston
Symphony, back in 1930, in part out of
themes from a ballet score, The Prodigal Son. It wasn't a success-too harsh
and outspoken for those days; but it
remained the composer's favorite and
shortly after World War II he went
back to do a rewrite, the present work.
It's good Prokofieff, combining the
lean, strong ideas of his early period
with the gentler, more harmonious orchestral style of his later days. It should
please no end, if you know other Prokofieff, for this version is perhaps his
definitive and best symphony; more
solid of texture, if less "popular" in
idiom, than the familiar Fifth. The new
Russian performance does it proud. Recorded sound is excellent, the stereo
full and alive though the hall sound
is somewhat drier than we are accustomed to in the West.
Sound: B+
Rossini: The Complete Overtures. Orch.
of the Accademia di Santa Cecilia, Pre -
Everest 3186/2 (2) stereo
Gotta keep an eye on this Everest
label and its dozens (so it seems) of
associated labels. You never know
what's coming next. This time it's a
winner. The eleven overtures, familiar
and unfamiliar (including all the usual
ones-"Lone Ranger" theme and all)
are played with an absolutely hair-raising accuracy and intensity, sheer Italian at its best. Every note is precise and
perfect; every change of mood is etched
like spring steel. Listen to the drum
rolls of La gazza ladra, beginning side
4! One is so machine-gun loud that
you'll jump a foot, the next so faint,
so dramatic, that you'll instinctively
crouch down, expecting the worst... .
Such flashing-eyed intensity! Now, you
can see where Toscanini got his style.
A fully modern recording, this, as is
implied by the use of the senior (and
most expensive) Everest label. List
price, that is.
Just what is meant by "complete" I
do not know, since Rossini composed
almost 40 operas and we have eleven
overtures. Do none of the others have
them? I'm not going to investigate.
More likely, the word just looks good
on a record album cover. Or maybe it's
the complete "famous" overtures? Who
cares. It's a splendid album.
Performance: A
Sound: B+
Liszt: Hungarian Portraits, Nos. 1-7; Valses
Oubliées, Nos. 1-4; Polonaises Nos. 1-2.
Edith Farnadi, piano.
Westminster WST 17127 stereo
"Okay, you guys, let's take it from section A ..."
Liszt's piano music is definitely coming back. Because, increasingly, we
now can hear its extra -ordinarily experimental, progressive semi -atonal
harmonies, where earlier generations
merely noted the frilly frosting, the
elaborate and difficult fingerwork, and
called it musical tinsel. Tinsel-yes.
But on a very solid tree.
APRIL 1968
(Continued from page 46)
But with the same kind of input
circuit and shunt injection, the voltage received due to feedback depends quite critically on the external
impedance connected. If this is a
pure voltage source (with zero resistance) it will short-circuit the
feedback (there will be none) The
source resistance is, in effect, part of
the feedback network under these
With an input where the controlling parameter is current, such as a
transistor, the situation changes a
little (Fig. 9). Parallel combination
is as simple as series combination is
with the voltage -input variety. But
Fig. 9. Comparison of methods of input
connection with a current input circuit,
such as grounded emitter transistor: (a)
shunt connection sums currents independent of external input impedance; (b) series
connection makes the result dependent on
both voltage and current from the external
input (its internal impedence).
IMPORTANT PAPERS will be presented on:
Acoustics and Hearing
Amplifiers, General
Amplifiers, FET Audio Applications Instrumentation Music
and Speech
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TECHNICAL SESSIONS: Monday through Thursday
morning, afternoon, and evening at 9:30, 1:30, and 7:30
except Wednesday 9:30 and 1:30 only.
AWARDS BANQUET: Wednesday evening May
7:30 p.m.
series injection, by developing a voltage across the emitter resistor, for
example, modifies input current in a
manner dependent on external
source impedance.
We could labor through all the
combinations of amplifier types and
varieties of feedback connection, to
cover all sixteen possibilities. But
there are some other basic causes of
complication that we want to show,
to get a complete picture of the problem in analyzing what feedback
really is and does.
EQUIPMENT EXHIBITION: Monday through Thursday;
Monday and Tuesday, 1:00 p.m. -9:00 p.m.; Wednesday
1:00 p.m. to 5:00 p.m. and Thursday 1:00 p.m. to
5:00 p.m.
Convention Program and Banquet Ticket Information
available from
Room 428, The Lincoln Building, 60 East 42nd Street
New York, New York 10017 (212-661-8528)
(Continued next month)
APRIL 1968
How Now, Dow Jones-Marlyn Mason, Anthony Roberts, Brenda Vaccaro, Hiram
Sherman and other members of the
Broadway cast; Peter Howard, cond.
RCA Victor LOC/LSO-1142 ($5.79)
Elmer Bernstein, an admirable musician, and composer of several dozen
film scores, including the memorable
"The Man With the Golden Arm,"
comes a cropper with his first Broadway show, "How Now, Dow Jones."
Max Shulman's musical, about the
world of Wall Street, stars Marlyn
Mason (a newcomer with an attractive
singing voice) as a girl whose job it is
to announce the latest Dow Jones averages over a loud -speaker system, and
Brenda Vaccaro, as a tour guide of the
financial district. Anthony Roberts and
the veteran, Hiram Sherman, head the
cast's male contingent.
With the exception of Miss Mason,
the show is weak on singers, and
weaker still on good songs. The best
tunes in a rather dreary lot are a ballad
called "Walk Away," "Gawk, Tousle
and Shucks"-which despite its dreadful title, is a catchy number in pseudoragtime rhythm, and a march, "Step To
the Rear." Helping not at all are Carolyn Leigh's lyrics, which work overtime trying to be chic and clever.
This ticket-tape tragedy notwithstanding, we need composers of Elmer
Bernstein's talent and expertise in the
Broadway theatre, and I hope we'll be
hearing from him soon again. RCA
Victor's sound is bright, vivid, and spacious, with good stereo effects.
Performance: B
Sound: A
Sound Track
Camelot (motion -picture soundtrack)Richard Harris, Vanessa Redgrave, and
Franco Nero; chorus and orch./Alfred
Warner Bros. B/BS-1712 ($5.79)
I have not seen the film version of
"Camelot" and am therefore unable to
evaluate its cinematic achievements;
but judging from the soundtrack recording, it is musically at least, a major
disappointment. Frederick Loewe's
score for the 1960 Broadway musical,
based on T. H. White's "The Once and
Future King," is his finest and most unappreciated achievement. In spite of a
libretto which often lacked focus and
direction, this sumptuously -mounted,
beautifully -scored show deserved a
longer run.
"Camelot," on screen was afforded
the chance for a new lease -on -life ... a
second opportunity, unrealized, because of performers who cannot meet
the vocal requirements of the songs
they are asked to sing. Richard Harris'
mannered, self-conscious performance
runs the emotional gamut from whispering to shouting, as he blusters his
way through the songs, without one.
iota of the understanding and poignancy Richard Burton, without much
more voice, brought to them.
Vanessa Redgrave, as Guenevere, is
off-pitch most of the time-assuming it
is she. (I can't imagine hiring a vocal
stand-in to sing so badly.) The songs,
"C'est Moi" and "If Ever I Would
Leave You" are competently, if not too
expressively delivered by Franco Nero
(or his singing counterpart?) as Lance-
The six numbers that comprise the
first side of this record were written for
a television color film called "Magical
Mystery Tour." The songs are the work
of John Lennon and Paul McCartney,
except for "Blue Jay Way" which was
written by George Harrison; and "Flying," an instrumental credited to the
quartet. The only tune I found appealing was "Your Mother Should Know,"
though the words are pure nonsense.
Another song, "I Am a Walrus," is
much more than nonsense-it's downright obnoxious, and ends with the
effect of a radio receiving multiple
The disc is filled out with five other
L & M collaborations, all equally undistinguished. The last song, "All You
Need Is Love," ends with what is probably the longest fade-out ever recorded;
symbolic, perhaps, of the Beatles' reluctance to say farewell. I wish I could
say the feeling was mutual.
The album contains a bound -in, 24 page booklet of photographs, mostly in
color, along with the story of the
"Magical Mystery Tour." The text is
illustrated with drawings by Bob Gibson that are hilarious, and by far the
most entertaining part of this pretenB.T.
tious enterprise.
Performance: B
Four numbers from the original
score are omitted, including "Parade"
charming, Prokofiev -like instrumental march. Alfred Newman, conducting a large orchestra, does his
usual musicianly job. The recorded
sound is good, if somewhat dry. Columbia has re -packaged their wonderful original -cast recording with Richard
Burton, Julie Andrews and Robert
Goulet, to coincide with the movie's release; but they needn't have bothered
-there's no competition here!
Performance: C
Sound: B
Beatle Magic
The Beatles: "Magical Mystery Tour."
Capitol (S) MAL -2835 ($5.79)
"Away in the sky, beyond the clouds,
live 4 or 5 Magicians. By casting wonderful spells they turn the most ordinary coach trip into a MAGICAL
MYSTERY TOUR. If you let yourself
go, the Magicians will take you away to
marvelous places." ... so runs the written preamble introducing the latest
Beatles L.P. And so, we are whisked
off to a world of electronic gimmickry
and outlandish stereo effects, which
might be sub-titled "Alice In Beatle
Sound: B
Instrumental Beatles Themes from
Pepper's Lonely Hearts Club Band-arranged and conducted by Peter Knight.
Mercury MG-21132/SR-61132 ($4.79)
These orchestral versions of the
tunes from The Beatles' "Sgt. Pepper"
album make very entertaining listening. Peter Knight, a British arranger
and conductor, not usually associated
with this type of material, turns out to
be a very versatile musician indeed,
as he leads a swinging orchestra of
moderate size through these imaginatively -scored Lennon & McCartney inventions.
All but four of the songs were orchestrated by Knight, and I especially enjoyed his renditions of "With a Little
Help From My Friends," "Lucy In the
Sky with Diamonds," and "She's Leaving Home," with some beautiful passages for strings.
Stand -outs on the flip side, are Bob
Leaper's arrangements of "When I'm
Sixty -Four"
a charming piece of
razz-ma-tazz, and "A Day In the Life"
the best track for demo purposes.
The sound overall is excellent, with a
clean and spacious stereo quality. S.T.
Performance: B+
Sound: B+
APRIL 1968
day and This Bird Has Flown, among
others. "Foreign Film Festival" also
has a lyric focus, with such attractive
entries as the love songs from Moulin
Rouge, Black Orpheus and The Umbrellas of Cherbourg, after which a
Hollywood roundup takes a turn for
the dramatic, with Exodus, Man with
the Golden Arm, etc. In the final group,
"Three by Mancini," the composer
makes his recording debut as a pianist,
playing Charade, Days of Wine and
Roses and the inevitable Moon River
with a smooth, fluid touch, if not a distinctively personal style. The stereo
sound is spacious, clean and wellR. S.
Encore: More of the Concert Sound of
Henry Mancini
RCA Victor stereo LSP 3887 $4.79
Mancini is generally recognized as
one of the more imaginative composers
and arrangers in Hollywood, and his
latest album gives further evidence of
his prowess in both fields. Occasionally he gets a bit too cute for comfort
(as when he intermixes the opening of
Beethoven's Fifth with the intro to the
Beatles' A Hard Day's Night), but
the rest of the time his settings provide lush, relaxed listening, with just
enough of a modern tang to keep things
from getting maudlin. The arrangements are for large orchestra, with the
strings carrying most of the freight,
but solo stints by piano, flute, trumpets
and saxophone adding plentiful dashes
of instrumental color.
Most of the program is given over to
movie music, compiled in three extended medleys, but Mancini starts out
with what he calls a "Portrait of the
Beatles." Whatever doubts might still
be lingering that Lennon and McCartney have written some genuinely
beautiful tunes, is removed by this fantasy, which includes Michelle, Yester-
Performance: B+
Sound: A
Bob Dylan
Bob Dylan: "John Wesley Harding" and
eleven other ballads. Bob Dylan (vocal,
guitar, harmonica and piano); with
Charles McCoy, bass and Kenny Buttrey,
Columbia CL-2804/CS-9604 ($4.79)
Bob Dylan is a talented tunesmith,
but as a singer, his appeal has always
eluded me. On this much -ballyhooed,
new disc of Dylan originals, the singing is more subdued than usual, with
less hand -wringing torment and torture. The songs seem to straddle the
fence, somewhere between Folk and
Country & Western. The ballad of
"John Wesley Harding," from which
the album derives its title, is about a
reputed friend of the poor, who travelled with a gun in each hand and never
hurt an honest man. "The Ballad of
Frankie Lee and Judas Priest" is a
sagging saga that takes 5 minutes and
30 seconds to unfold and would try the
patience of all but the staunchest Dylanites.
The obscure lyrics of all these songs
are hardly made more intelligible by
the singer's slurring, monochromatic
delivery. Well, I suppose you either get
the Dylan "message" or you don't .. .
and those of us who don't, are more
than likely to feel that the man is putting us on. Columbia's stereo effects are
predictable with guitar and bass on the
left, drums on the right, and Dylan,
front and center.
Performance: B
Sound: B
AS -8
12" Woofer has
30 oz. magnet
Midrange horn,
tweeter L. C.
Crossover network
Price: $189.00 Net
Impedance: 8 Ohms
Power Handling:
60 Watts peak
Presense and
Brilliance controls
Only after sound perfection was reached from this
Speaker System was UTAH ready to incorporate it
furniture cabinetry. After all, UTAH'S primary business
neering and developing the epitome of sound perfection.
Sir, the "brass" (they're the sound engineering experts) sa
that the sound is there. We believe that you, the expert at
choosing fine furniture will agree the eye appeal is there.
This provincial model is one of a family of three. There'
Early American version as well as a Contemporary style.
See your dealer, or write UTAH for complete information.
35/20,000 HZ.
Check No.
APRIL 1968
71 on
Reader Service Card
actual field recordings has been going on for very nearly as long as the
gramophone has been extant. Bartok
and Kodaly made early documents
of this type in Hungary, and Percy
Grainger carried out similar field recording projects in the British Isles.
In the United States, important
work was done in the Thirties and
Forties by the Lomaxes and in the
Fifties by Frederic Ramsey, Jr. and
several others. But until the development of the first professional, lightweight portable tape recorders in the
late Fifties, quality of sound was
rather grim and highly variable.
When the Nagra, a compact tape
unit whose specifications compared
favorably with studio recorders,
came on the scene, there was reason
to hope that the situation would
change. This machine not only operated from a battery pack, it also provided the necessary current for a
condenser microphone. With it, the
field recordist could collect performances in remote regions lacking
power lines, and the results, asdemonstrated by some pioneering location recordings made by Emory
Cook in 1956 or 1957, could be every
bit as fine as what could be done in
a studio. It gave one reason to hope
that the folklorist would soon be
turning out platters that could be
enjoyed rather than studied. But a
sampling of some of the recent re-
leases of field recordings makes it'
clear that there is not much technical improvement between work
being done today and that accomplished on old Library of Congress
Not all of the blame can be placed
on the failure of field recordists to
utilize the fine equipment available
to them today. Professional sound
recording equipment is not likely to
deliver truly professional results unless it is handled by knowledgeable
sound engineers. And the men who
comb our southland for new songs
and singers are hardly trained recordists. There are a host of problems, even when skilled engineers do
the recording. Acoustics are either
too dead or too reverberant, background noise cannot be eliminated,
and often the performers are so unused to recording that they do not
know how to work in front of a microphone.
The best way around all of the
problems is simply to transport the
performers to the recording studio,
and this is the general approach of
BluesWay, one of the newer labels
devoting its attention to folk blues.
Its recent recording of Jimmy Reed
(Soulin', BluesWay Stereo BLS 6009 [$4.79]) is a perfect example of
how splendid a blues recording can
be when a fine singer gets together
with a group of experienced musicians under the controlled conditions
in a good studio. The Reed guitar,
harmonica, and voice are all heard in
proper balance as this vigorous performer delivers his message.
T-Bone Walker, the Texas blues
singer, is heard on another studio
recorded set (Stormy Monday
Jimmy Rushing: Listen to the Blues
Vanguard Everyman Mono SRV 3007
A welcome reissue on this low-price
series of a fine blues disc that brought
Rushing together with Pete Johnson,
Lawrence Brown, and several of his old
Benny Moten, Count Basie collaborators. For its age, the sound is fine.
Performance: A.
Sound: B
Blues, BluesWay Stereo BLS-6008
[$4.79] ). It features the same highquality engineering as the Jimmy
Reed platter, and a nine -man combo
well matched to Walker's exhuberant style.
Blues recordings made in the field
are offered by Arhoolie and Blues
Classic, two small Berkeley, California firms run by Blues scholar -collector, Chris Strachwitz. They offer
indifferent sound, but three recent
releases are of particular interest
both for their high musical quality
and the light they focus on areas
that have been only partially documented to date. Blind James Campbell and his Nashville Street Band
(Arhoolie Mono F1015 [$4.98] )
features a type of group that is rarely
encountered in the South today, the
blind street singer accompanied by a
fiddle, guitar, and occasional bits of
trumpet and tuba. The group's style
combines jazz, blues, country fiddle,
and gospel. In spite of its mediocre
sound, this disc has moments that
swing, surge, and explode.
Texas Blues, the Early '50s,
(Blues Classic Mono 16 [$4.981)
offers thirteen songs sung by nine
singers, among them Frankie Lee
Sims, John Hogg, Texas Alexander,
and Lightning Hopkins. Another collection, Memphis and the Delta
1950s, (Blues Classics Mono 15
[$4.98]) offers no less than 14 different singers in as many songs. Quality
on this set ranges from fair to miserable, but the singers, who include
Roosevelt Sykes and James Cotton,
provide an interesting contrast in
styles, and, in the one-man band of
Joe Hill Louis, some real excitement.
Esquire's All-American Hot Jazz
RCA Victor Mono LPV-544
Jelly Roll Morton: Mr. Jelly Lord
RCA Victor Mono LPV-546 ($4.79)
A Vintage reissue of the special recordings made in 1946 of the winners
of the Esquire Magazine poll, together
with some Coleman Hawkins and
Lucky Thomson waxings of the same
period. Armstrong, Elligton, Hodges,
Don Byas, Billy Strayhorn, Chubby
Sixteen Vintage series reissues, dating from 1926 to 1930, of group recordings that included such musicians as
Johnny and Baby Dodds, Ward Pinkett, Bubber Miley, Johnny Hodges,
Alber Nicholas, Orner Simeon, George
Baquet, and Wilbur DeParis. The
swagger and intensity of Morton's
happiness permeates every groove of
this skillfully transferred set.
Jackson, and many others are heard
in waxings that included the Hodges,
Byas, Strayhorn, Palmieri Gone With
the Wind.
Performance: A to C
Sound: B
Performance: A+
Sound: B
APRIL 1968
Jazz Veterans Score
Pee Wee Russell & Henry Red
The College Concert
Impulse Stereo AS -9137 ($5.98)
Pairing veterans Pee Wee Russell
and the late Henry Red Allen with
three young contemporary jazzmen:
Steve Kuhn, piano; Charlie Haden,
bass; and Marty Morell, drums, has resulted in a fresh -sounding disc that
demonstrates better than any other
record the breadth of expressive imagination of Allen. His Body and Soul
vocal is a fascinating commentary on
his instrumental style.
Perf ormance: A
Sound: B
Latin Touch
Charlie Byrd: More Brazilian Byrd
Columbia Stereo CS 2692 ($4.79)
Swinging freely against the background of an orchestra under Tom
Newsom, Charlie Boyd devotes most of
his album to a new Brazilian rhythm
with a 5/4 beat. Called the Jequibau
(pronounced Zhak-ee-bough), it sounds
like an ideal bit of exotica for either
dancing or background.
Performance: A
Experts say this is
the best integrated turntable
in the world.
Too bad everybody doesn't know that.
In the Thorens TD-150AB, the tonearm and turntable have a unified suspension,
minimizing vibration and acoustic feedback, Speeds of 331/3 and 45 rpm are
derived from a Thorens double motor on a single rotor shaft, turning at the
unusually low speed of only 425 rpm.
The result is completely silent and absolutely precise operation. Such factors
as rumble and wow are virtually eliminated. An exclusive low mass, plug-in
shell, adjustable vertical tracking angle, pneumatic tonearm cueing or lowering device, a handsome slim line chassis are among the many features that
make this instrument a proud possession for any enthusiast. TD-150AB; $99.75.
TD -150)
(Also available without tonearm & base
For more details and a FREE Record Omnibook, see your hi-fi dealer, or
Check No. 72 on header Service Card
Sound: B
Live Better Electronically With
Willie Bobo: Juicy
Verve Stereo V6-8685 ($5.98)
The special flashy swagger that Willie Bobo imparts to his Latin percussion jazz -making is again in evidence
as this drummer, composer, arranger
steers his group through a dozen tunes
that are well suited to the bouncy Bobo
style. -Included are Knock on Wood,
Mating Call, Mercy, Mercy, Mercy,
Felicidad, Juicy, Ain't Too Proud to
Beg, Music to Watch Girls By, Dreams,
Dis -Advantages, Roots, Shing-A-Ling,
and Bobo's own La Descarga del Bobo.
There's just a mite less of the jazz freedom in this group of performances than
in his last couple of releases. Before
heading out on his own, Bobo worked
first as a Latin percussionist with Tito
Puente and Mongo Santamaria, later
he played jazz percussion with Cal
Tjader. Whether this release indicates
a trend toward a more popular performance style it's too soon to tell. It
is clear that some form of evolution is
in process, and that Willie will continue to bear watching.
Performance: A
Sound: A
with Integrated Circuits (IC's) & FET'S
Inc. Walnut grained
Metal Case
LR -1500T
Úki Iä7 ETTR
1968 CATALOG NO. 680
512 Pages
Dept, AK -7. P.O. Box 10
Syosset L.I., N.Y. 11791
Send me the FREE 1968
Na me
LAFAYETTE Catalog 680
AD -8
Add reºs
ICheck No. 73 on Reader Service Card
APRIL 1968
No Money Down
No Money Down
From right channe
R19 15k
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Computer Logic Control
R11 15k
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R8 15k
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28V to terminals No.8
R24 1k/7W
In the league of nimble -fingered
tape -handlers there exists a re-
current problem. It has been
demonstrated time and again that
anyone can ruin a valuable tape by
absentmindedly outsmarting the
interlock system of an otherwise
safe tape recorder.
In answer to this problem and similar problems arising in automated
and remote control applications, the
CROWN Pro 800 was designed. This
recorder has a computer logic system using IC's which prohibit all
such destructive operations.
The CROWN computer stores the
last command given it in its memory
(forgetting all previous commands)
and by a continuous knowledge of
the operating state of the machine
(motion and direction), it takes all
the necessary measures and
executes the command. This is all
done without time -wasting delay
Computer Logic Control brings
to you rapid error -free tape handling. It is actually impossible
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Check No. 74 on Reader Service Card
Contact No. on
etched circuit board
25 1500/7W
FReceptacle No. on
card socket
Only one channel shown
(except power amp)
Capacitor values-whole numbers,NF
10/25 denotes electrolytic -105F, 25 V.
Fig. 6-Three -channel Electronic Ciossover Circuit.
Schematic of three -channel electronic crossover network (Audio, February 1968) incorporating corrections (see letters).
(Continued from page 10)
Among a number of mistakes in the
schematic, there is another in the calculations for the voltage divider. R24
and R25 cannot produce 28 volts if the
two crossover circuits together draw
16 ma. (We omitted the 30-V. Zener
diode across C21 which is used in the
original Acoustech XI with the PM
preamp. With this in place, there is
28-V. across R25, although there is too
much current through the Zener. R24
should be 1000 ohms.
Please continue construction articles
for those of us who still have, and plan
to keep, separate tuners, preamps, and
power amps.
Madison, Wisconsin
I have just read your article on the
electronic crossover, and I have one
suggestion: warn your readers that
horn -loaded mid- and high -frequency
units can be ruined when connected
directly to power amplifiers, even when
properly designed low-level crossover
circuitry is used. Low -frequency transients generated by the power amplifier during turn -on and turn-off (especially transistorized units) may well be
enough to damage a delicate diaphragm
The solution is to use a simple highpass filter between the driver and the
power amplifier. This can be designed
so that it comes into effect at a lower
frequency than the low-level- crossover, and thus doesn't change the overall characteristics of the system. For
example, if the low-level crossover is
set at 500 Hz, a capacitor can be inserted in series with the high-frequency
driver to attenuate the signal below
250-300 Hz.
James B. Lansing Sound, Inc.
Los Angeles, Calif.
(The last suggestion covers a question we have often heard-but not yet
experienced-about damaging tweeters
and midrange drivers. We did introduce a 6 -pf capacitor in the output
circuit of the tweeter amplifier, it will
be remembered. For a 500 -Hz crossover, a 40-p,F motor -starting capacitor
would be ideal for a 16 -ohm mid -frequency driver. The new schematic will
answer most of our readers questions,
and we hope that everyone who read
the article will also see these comments
and corrections.Ed.)
I am more excited about your electronic crossover project in the February
issue of "Audio" than any other construction project you have printed in
Mechanicsburg, Pa.
APRIL 1968
Good sound also has its special
look. And the 711B is no exception. It has the look of quiet engineering authority. Styling is
elegant, with a walnut -grained
trim and a rich satin black and
gold panel.
Behind its handsome face are
some very sound electronics
(FET's, IC's and fully silicontransistorized circuitry), for some
very sound sound. Between station noise is completely eliminated by Altec's new muting
At 100 watts, the 711B is engineered to drive almost any
speaker system you may prefer.
(And naturally we prefer you'd
choose an Altec system.)
Altogether, the 711B is an
instrument that's more than
worth seeing and hearing. Especially at only $399.50. Visit your
Altec dealer, or write us for free
ABZ's of FM
(Continued from page 34)
is basically a "line -of-sight" form of
transmission, the higher the location of
the antenna above sea level, the further
the distance to the visible horizon. As
an example, a transmitter having a
power of 20 kW will be received with
a signal strength of 1000 microvolts per
meter at a distance of 32 miles if its
transmitting antenna is 500 feet above
sea level. Raising the antenna to an
elevation of 1000 feet above sea level
Fig. 6 -Corrective network attenuates high
frequencies so that FM at output of the
phase modulator is no longer a function
of the audio modulating frequency.
would result in a signal strength of
1000 microvolts at a distance of about
43 miles from the transmitter site. At
this elevation, reducing the power of
the transmitter to 5 kW would reduce
the 1000 microvolt "contour" to only
about 35 miles.
Channel separation & interference
While the FCC generally assigns frequencies at least 800 kHz apart in the
same city, objectionable interference is
not considered to exist when the channel separation is 400 kHz or greater.
Therefore, FM stations in the same
general are often assigned to 400
kHz apart. Of course, the receiver's
ability to separate stations only 400
kHz apart is extremely important, and
recalls earlier discussions in this series
concerning adjacent channel interference, capture ratio, and associated
measurement which describe a receiver's ability to discriminate between
one station and the next.
The FCC considers the necessary signal strength for satisfactory service in
city areas to be 1000 microvolts/meter.
In rural areas, far removed from highways (and associated noise produced
by automotive ignition) 50 microvolts/
meter of signal strngth is deemed adequate.
Signal strength in an area and signal
intensity actually reaching your receiver may be two entirely different
numbers unless you pay careful attention to antenna requirements.
Tunes like a breath. Or like the
precision instrument it is, with
its finely balanced, ball -bearing
tuning mechanism and its accurately calibrated scale.
The experts say it has a hot
front end. And that means
exceptional sensitivity -better
than 1 9 microvolts. Capture
ratio is 2.5 dB.
Of course this 100 watt
receiver makes use of all the
latest sound electronics: field
effect transistors, integrated circuits, silicon transistor circuitry
If you're anywhere near the
market for a $399.50 receiver,
your Altec dealer will be glad to
put you in touch with the 711B.
Or write us for a free catalog.
Division of 41-7,77 Ling Altec, Mc..
1515 South Manchester Avenue:,
Anaheim, California 92803
Division of `2 =C' Ling Aftec, Inc..
1515 South Manchester Avenue.
Anaheim. California 92803
Check No. 75 on Reader Service Card
APRIL 1968
If you're around
Franklin Lakes, N. J.
and like shopping
great Hi-Fi stores see this man...
Rates: 25% per word per insertion for noncommercial advertisements; 50¢ per word for commercial advertisements. Frequency
discounts as follows: 2 times, less 15°/0; 6 times, less 20%;
12 times, less 30°/o. Closing date is the FIRST of the second
month preceding the date of issue.
Frank D'Alessio, Owner of
Stereo Center, 792 Franklin
Lakes, New Jersey
Franklin Lakes Stereo Center
in a northern New Jersey
Franklin Lakes
Ave., Franklin
quality store
community with
retailer's reputation in
long-time residents. A
that type of community depends on the honest
quality of his merchandise and the value he
offers his patrons. "We like the Pioneer line,"
Mr. D'Alessio said "because it does just that
gives our customers top quality and,
feature for dollar, excellent value."
BLANK CARTRIDGE TAPES. 34 -minute 4 or
8 track, 60 -minute cassette-$1.50 each.
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Illinois 60605. Dept. PP.
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CH 3-4812
140 Smith St., Farmingdale, L. I., N. Y. 11735
Walker St., New York, N. Y. 10013
CA 6-7785
(516) 694.7720
Check No. 24 on Reader Service Card
can't buy a better
tape at any price!
Complete line of cassettes, 4 and 8 track
cartridge tape, reel-to-reel tape and 1/2
and 1 inch video tapes.
Write for complete details.
IRISH TAPE 458 Broa,; y,
N.Y. 10013
PROTECT YOUR LPS-Heavy poly sleeves
for jackets 5¢, Round bottom for records
31/2¢ ea. New LP jackets, White 20¢, Colors
25¢. Min. order $5.00. LP Supplies, Hill burn, P.O. New York.
disc recordings made from live or recorded material. High quality. Reasonable
rates. Audio -Tech Laboratories, 2819 Newkirk Avenue, Brooklyn, N. Y. IN 9-7134.
M. RETTINGER, Consultant on Acoustics.
Analysis. Room Design. Noise Reduction.
5007 Haskell Ave., Encino, Calif. Tel: (213)
RENT STEREO TAPES-75¢ week. Catalog.
Art's, 14131/2 N. Mariposa Ave., Hollywood, Calif. 90027.
CASH for used audio components-describe and price. Ask for free list-Marco
Electronics, Box 336A, Winter Park, Fla.
MUSIC LOVERS, background music, continuous, uninterrupted, from your FM
radio, using new inexpensive adaptor. Free
literature. R. Clifton, 11500-E N.W. 7th
Ave., Miami, Florida 33168.
SONY 777 Deck, new heads just installed.
Excel. cond. $450.00. Box AA8-1.
AKG D -24E Microphone, $145. Factory overhauled 10/67. T. J. Immel, 1524D Spartan Village, E. Lansing, Mich. 48823. 517355-3115.
DISC RECORDING EQUIPMENT: Cutter heads, Recording Amplifiers, and Lathes.
New and used. From Rek-O-Kut to Scully.
Send requirements. Wiegand Audio Labs,
221 Carton, Neptune, N. J. 07753.
British. 180° dispersion. This mid-range
treble can be used with any woofer. Brochure, reports, and prices sent on it and
full -range systems manufactured in Canada. Olson's Audio House. Box 1075.
Wetaskiwin, Alberta, Canada.
SCULLY Professional Tape Recorders, from
1 to 12 tracks, complete recording studios
available in prewired console cabinets
starting at $8,000.00. 70°/o financing. WIEGAND AUDIO LABORATORIES, 221 Carton, Neptune, N. J. 07753.
Klipschorn, Tannoy, Altec, Rectilinear AR,
Inc., Wharfedale, Dynaco, Sherwood, Ken wood, Teac, Uher, Garrard, Benjamin,
Superior Sound, 621 S. Main St., N. Syracuse, N. Y. 13212.
$80,000.00 hi -fidelity retail
store inventory. New/used equipment:
Ampex, Marantz, Fisher, others. HewlettPackard test equipment. Free list-Marco
Electronics, Box 336A, Winter Park, Fla.
AUDIO: 52-66, $10/year. Box AJ8-1
Check No. 76 on Reader Service Card
APRIL 1968
REK-O-KUT Rondine Transcription table
with Shure SME Arm-one or both-make
offer. Harold Kuever, 1401 S. Boyle, St.
Louis, Mo. 63110.
CITATION "A", "II", Illx, Pre -Amp, Amplifier, Tuner. Good cond. $325.00. Gary
Kohnke, 3070 S. 54th St., Milwaukee, Wis.
AM -FM GENERATOR, Boonton 202E with
207G Univerter. 50KHz to 216 MHz. $500.
Oscilloscope, Watermen S -14A (High -Gain
Pocketscope). $69. Alvin G. Voigt, 230
Oneida St., Pittsburgh, Pa. 15211.
TWO SYNCRON S-10 Condenser Microphones with wind screens. One year old,
$210 each. Don Sherrill, 14598 Lorain
Ave., Cleveland, Ohio.
HAMMOND reverberation! New mechanism-$4.-CAL'S! Box 234, Dearborn,
Michigan 48121.
clever ...
fellows at
AMPEX (300-2C, 300C, 354P, PR10-2,
601-2, MX10, 2-2010's) Rek-O-Kut disk
cutter, Concertone 505, EV 665, Syncron,
AU7a's, Altec 21D, Box 15058, Phoenix,
mail $5, sea $3. Intercontinental, CPO
1717, Tokyo, Japan.
HARPSICHORD: Same as owned by Philadelphia Orchestra and RCA Victor. In kit
form for home workshop assembly, $150.
Clavichord kit, $100. Free brochure. Write:
Zuckermann Harpsichords, Dept. R. 115
Christopher St., New York, N. Y. 10014.
new, na-
tionally advertised brands, $10.00 above
cost. Arkay Sales Company, 1028-H Commonwealth Avenue, Boston, Mass. 02215.
AWAY. Send us $19.95 and any old
cartridge. We will ship PREPAID any one
of the following top rated elliptical diamond stereo cartridges NEW: Pickering
V15AME3, Empire 888SE, Shure M55E,
Stanton 500E, Shure M80ED (for Lab 80),
M80ED19 (for Dual 1019). Write for lowest quotations all stereo components.
DEFA ELECTRONICS, 2207 Broadway, New
York, N. Y. 10024.
CITATION "A" good condition. See
AUDIO Profiles 10/62 and 4/63 $175.00
w/cabinet. Robert E. Raymond, 730 West
Washington Ave., South Bend, Ind. 46601.
for money saving stereo catalog AM and lowest quotations on your individual component, tape recorder, or sys-
FOR SALE: Complete Mono Disc Cutting
Outfit, consisting of Presto 8DG Lathe,
33/45/78 RPM. Aluminum Turntable with
Vacuum Hold-Down. Independent Motor Driven Cross-Feed for Manually Controlled Variable Pitch. Westrex 2B Cutter,
McIntosh 275 Specially Revised Amplifier
-Variable Equalizer -Preamplifier. United
Audio Peak Limiter, 30 -watt McIntosh
Monitor Amplifier, Magnecord M-90 1/4"
Single -Track Tape Machine. Latter Four
Items Rack Mounted. In Good Operating
Condition-Inspection Invited. $4500.00
Plus Transportation from Midwest. Box No.
WANTED: Used RCA 77-BX mike. Send
price and condition. Bill Hagara, 2003
Spruce, Duncan, Okla.
THORENS TD -124, 4 -speed turntable, Ortofon 16" arm, used 90 days, like brand
new. $135. Yoder, 239 E. Budd, Ontario,
Cal. 91761.
CITATION "A," $100; "B," $125. HK
F1000T Tuner, $90; 2-AR3s, $90 each. Albert Peloquin, 505 S. Birney, Bay City,
First they put a woofer/
tweeter in their stereo headphones to provide a full range
of response without distortion.
They also added a complete
crossover network right in the
for an authenticearpiece
ally fine speaker system in
miniature. Just what the true
stereo buff ordered!
Then they extended their line
in depth for the Hi-Fi enthusiast and for Education, Broadcast, Aviation, Marine and
Communications use.
they've developed a
great new model, the ST -PRO -B
the last word
. just about
in a professional quality headphone.
WANTED: used EMT echo chambers
mono or stereo. Vanguard Records, 71 W.
23rd St., N. Y. C. 10010-212-255-7732
Ext. 34.
CONCERTONE 20/20 Recorder -Amplifier
TWA -1. Eiskamp, 1185 Woodside, Eugene,
Oregon 97401.
FREE! Send
tem requirements. Electronic Values, Inc.,
200 West 20th St., New York, N. Y. 10011.
ALTEC LANSING Drivers (806A or 802D)
and horn. State price & cond. J. Geyer,
Pretty clever, those fellows at
Superex. All they do is give
you the edge in quality, value
and forward -looking audio engineering. Ask your dealer for
a demonstration.
Write for complete catalog.
Radford Place, Yonkers, N.Y.
2431 W. Hazelwood, Phoenix, Ariz.
WANTED: Marantz electronic crossovers;
Electro -Voice 18WK woofer. Send price &
condition. Box AA8-2.
SYSTEMS ENG., B.S. M.B.A., 7 yrs.
top mfr.
age 30. Wide exp. Want college teaching/
cmptr. ctr. work. Box AA8-3.
Check No. 77 on Reader Service Card
APRIL 1968
a special
If you're around
Syracuse, N.Y.
and like shopping
great Hi-Fi stores see this man...
Acoustic Research, Inc.
Altec Lansing
Audio Engineering Society
Benjamin Electronic Sound Corp. ... 39
Bogen Communications
Cover Ill
British Industries Corp.
(USA) Ltd.
Classified Ads
Crown Internataional
Warren Frank, Owner of Stereo World
2910 Erie Blvd., Syracuse, N. Y.
Stereo World is a high fidelity store offering
the finest lines of components. With regard
to his Pioneer line, Mr. Frank states,
are concerned with helping the public achieve
maximum value for the money they spend.
Pioneer components offer a level of performance available from most other manufacturers
only at much higher prices
P10NEER ®(
140 Smith St., Farmingdale, L.I., N.Y. 11735
(516) 694.7720
Dolby Laboratories
Dynaco, Inc.
Electro -Voice, Inc.
1, 40-41, Cover IV
Elpa Marketing Industries
W., Company
Fisher Radio Corporation
11, 73
Garrard Sales Co.
Gotham Audio Corporation
Gauss Electrophysics, Inc.
Heath Company
Check No. 22 on Reader Service Card
Hi -Fidelity Center
Kenwood Electronics, Inc.
Klipsch & Associates
Koss Electronics, Inc.
Lafayette Radio
3M Company
Marantz Company
Martel Electronics, Inc.
Morhan National Sales Co.
McIntosh Laboratory, Inc.
Pickering & Co., Inc.
ends the mixup over
Sound Mixers
Confused as to what a sound mixer
should do for your sound system?
Or wondered why some mixers cost
only a few dollars while others run
into the hundreds?
Get all the facts from Report 307TR
direct from Switchcraft's Research
Dep't. Find out why you should have
a pre -amp mixer ... why equalization
for magnetic phono cartridges is a
must ... the advantages of a
stereo/monaural mixer, plus many
other searching questions that will
help you decide on the equipment
that's best for your sound system.
The report is free. So is a look at
Switchcraft's Studio Mix MASTER
4 -channel, stereo/monaural sound
mixer at your local dealer.
ON Hl -F1
We invite your test of our
"We Will Not Be Undersold Policy."
15-day money -back guarantee.
2-yr. unconditional guarantee parts &
labor no
charge, at
station or factory
We accept Diner's Club charges
Trade-ins-highest allow. Send your list..
Most items shipped promptly from our
250,000 inventory, fully insured.
Our specialty-APO & Export.
23rd yr. dependable service-world wide.
Rated #1 service-satisfaction according to
nationwide survey.
Waste for Our Price First!
You'll Be Glad You Did!
'The Nonse of Low Low Preces"
239- V East 149th St.
New York, N.Y. 10451
Check No.
on Reader Service Card
Pioneer Electronic U.S.A. Corp. 15, 76, 78
Sansui Electronics Corp.
Scott, H. H., Inc.
Sherwood Electronic Labs, Inc
Shure Brothers, Inc.
Sony Corporation of America
Cover II
13, 44
7, 23
Stanton Magnetics
Superex Electronics Corp.
Switchcraft, Inc.
Tandberg of America, Inc.
United Audio Products
University Sound
Utah Electronics
* Portable, battery powered, with completely solid state circuitry.
Four channels, accepts 1 to 4 monaural
inputs or up to 2 stereo inputs. Separate
volume control per channel plus master
volume control.
* Two channels equalized for monaural or
stereo magnetic phono cartridges. Auxiliary inputs for high level input signals.
* Distortion 1% max. at 1.5 v. output.
Frequency response 20Hz to 20KHz.
Signal to noise ratio 60 db referred to 1
my. input. Up to 2 v. R.M.S. output.
Check No. 78 on Reader Service Card
APRIL 1968
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