Tqpe^Reeorder f^ualization Noise Reduction Techniques Building a VU Meter An Op-amp ...

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that you wanted better
sound reproduction,
and we took it
from there.
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PIONEERS NEW
An acoustic achievement th
universally preferred so
; R SPEAKER SYSTEMS.
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Too often these days superlatives are
used to camouflage mediocrity. Let's R700 R500 R300
just say you'll be excited with the Speakers 12" woofer, midrange |10" woofer, 10" woofer,
magnitude of the achievement of the horn, multicell horn 5" midrange, horn tweeter
new Pioneer series R speaker
super tweeter horn tweeter
systems, once you hear them. They
represent the culmination of our more Maximum 75 watts 60 watts 40 watts
than six years of intensive research in Input Power
tehvise rsye priheass ea loonf es.peaker design on just Crossovers I 750 Hz, 14,000 Hz | 800 Hz, 5,200 Hz 6,300 Hz
We investigated, tested and Dimensions 13%"x24"x12He" 13"x221/2"x11"
|l5"x26"x13%6"
evaluated every known area:
frequency response, dispersion, Price j $229.95 I $159.95 $119.95
distortion, transients, drivers,
configurations, cabinetry — rejecting, The acoustically padded
accepting, improving until we were enclosures are sturdily built and faced
completely satisfied that we had the with handsome two-piece, two-color,
perfect combination. The sound most removable grilles. The staining
people would prefer when compared process of the hand selected walnut
with the conventional speakers now requires ten steps alone, and utilizes
available. an exclusive oil created by Pioneer.
The story behind the grille Each unit is produced as if it was the
To achieve this exceptional sound only one.
reproduction, Pioneer has endowed Sound-absorbing foam
the new series R with a host of polyurethane surrounds the woofers
meaningful refinements that have of the R700 and R500 to reduce
become the hallmark for our distortion even further. The three R
extensive collection of high fidelity series models each employ long-throw
components. voice coils providing greater cone
Flush mounting. Unlike other movement for higher excursions.
speaker systems on the market today, Unique concave center pole
the R series' drivers are flush mounted
design and pure copper cap/ring
to the face of the enclosure, rather combination. The concave center pole
than recessed. Combined with the of the drivers' magnetic structure is
advanced design of the individual covered with a pure copper cap. Not
speaker units, there is added vitality only does this reduce the inductance
to the mid tones and wider dispersion. of the voice coil, it also decreases
the voice coil's intermodulation
distortion generated by the magnetic
field. The result: vastly improved bass
and midrange transient responses.
Another example of Pioneer's meticu
lous engineering detail.
Improved design horn tweeters
of die-cut aluminum have completely
replaced the more conventional (and
less costly) cone and dome-type There are many technical
tweeters in the entire series. You can reasons why you should buy a pair of
hear the difference with wider the new Pioneer series R speakers
dispersion, and you gain all the systems. But, in the final analysis,
Conventional New up-front advantages of horn drivers, such as when you compare them with com
recessed speaker flush mounting of
high transient response and lowest parably priced speakers at your
mountings. Pioneer series R.
distortion. Pioneer dealer, their absolute
Exclusive FB cones assure robust
Crossovers are precisely de superiority in sound reproduction is
bass, clear mid and high tones,
improve damping, while keeping signed in each model. In contrast to why you will buy them.
distortion at an absolute minimum. other speakers that rely on the U.S. Pioneer Electronics Corp.
High input signals are handled with capacitance method only, Pioneer 178 Commerce Rd., Carlstadt,
has combined both inductances and New Jersey 07072
complete ease.
capacitances for minimum inter
modulation distortion. And you'll
never hear bass tones wandering to
the tweeters, or highs intruding on the
woofers. You couldn't ask for better
linear response.
OvD PIONEER
when you want something better
West: 13300 S. Estrella. Los Angeles 90248 • 1500 Greenleal, Elk Grove Village, III. 60007 • Canada: S. H. Parker Co., Ontario
A U D I O
WE'VE /WflDE
THE BEST
EVEN BETTER
Successor to RADIO Est. 1917 Vol. 56, No. 10
OCTOBER 1972
FEATURE ARTICLES
18 Noise Reduction Techniques H. W. He/Iyer
26 Tape Guide: All About Tape Recorder Equalization Herman Burstein
34 A Quiet Phonograph Preamplifier James P. Holm
...3 36 Language of High Fidelity, Part V Martin Clifford
48 Constructing a Peak-Reading VU Meter E. A. Ballik
NEW MODELS
BETTER! CASSETTE SURVEY
56 Introduction and Testing Procedure 16 Models
57 Chart of Characteristics and Test Results
58 Discussion of Individual Models
EQUIPMENT PROFILES
i /VE W N\0DEL 10/10 67 Panasonic Tape Deck Model 736US
The frequency curves 69 Scott AM/FM Stereo Receiver Model 477
are actual tracings from
72 Dynaco Stereo FM Tuner Model FM-5
a new Sharpe produc
tion Model 10/10. 74 Eastman Speaker System Martin Crescendo 430
Improved design of
the famous top- RECORD AND TAPE REVIEWS
rated Model 10A.
ii Smooth, brilliant, 82 Timeless Recordings Edward Tatnell Canby
full response. 85 Recorded Tape Reviews Bert Whyte
Striking new decor. 86 Classical Record Reviews Edward Tatnall Canby
n/E i/t/ [vmRh in 88 Weingarten Looks At... Sherwood L. Weingarten
For new bright sounds 91 Jazz & Blues: Newport/N. Y.C. Martha Sanders Gilmore
to satisfy the highest
standards of discrimi
AUDIO IN GENERAL
nating professionals
and audiophiles 4 Coming In November 14 Dollars For Tapes
alike. Smart new 4 Audioclinic Joseph Giovanelli 16 Editor's Review
appearance with 6 Dear Editor . . . 76 Advertising Index
advanced acousti
8 What's New In Audio 98 Classified Advertisini
cal designs.
10 Behind the Scenes Bert Whyte
/UEIA//WODEL7/7
See this new budget-
priced version of one
of Sharpe s most popu
lar models. Price and
^ quality make it a
"best-buy." Light editor George W. Tillett publisher Jay L. Butler
weight stereo associate editor Edward Tatnall Canby marketing director Sanford L. Cahn
listening. Rich new assistant editor Eugene Pitts cover design John Kwasizur
ebony decor. Your design David Adams subscription manager Jean Davis
Sharpe dealer will
advertising production Sharon Mancini
i gladly demonstrate
the complete
Sharpe Stereo line. contributing editors: Herman Burstein, Martin Clifford, Leonard Feldman,
Richard Freed, Joseph Giovanelli, C. G. McProud, Harry E. Maynard, Alexander
SHARPE Rosner, Sherwood L. Weingarten, Bert Whyte
A U D I O
DIVISION AUDIO (title registered U.S. Pal. Off.) is published by North American Publishing Co., Irvin J. Borowsky, President:
Frank Nemcycr and Roger Damio. Vice Presidents; R. Kenneth Baxter. Vice President/Production: Nate Rosenblatt.
SCINTHEX, INC. Promotion Director: Mary Claffey. Circulation Director.
Tonawanda, N.Y. RATES-U.S. Possessions. Canada, and Mexico, S6.00 for one year; S 10.00 for two years; all other countries, S9.00 per year.
14150 Printed in U.S.A. at Columbus, Ohio. All rights reserved. Entire contents copyrighted 1972 by North American Publishing Co.
Second class postage paid at Philadelphia, Pa. and additional mailing office. Back issues, $2.00 each.
REGIONAL SALES OFFICES: Jay L Butler. Publisher, and Sanford L. Cahn. Marketing Director. 41 East 42nd St.. New
Export Agents York, N.Y. 10017, telephone [phone].
ELPA MARKETING Jay Martin, 15010 Ventura Blvd., Sherman Oaks, Calif. 91403, telephone [phone].
INDUSTRIES. INC. REPRESENTATIVES, United Kingdom: The American Magazine Group, 27 Maddox St.. London, W I. England.
Continental Europe: John Ashcraft. 12 Bear St.. Leicester Square, London W.C. 2, telephone [phone]. For Benelux and
New Hyde Park.
N.Y. 11040 Germany, W.J.M. Saunders, Mgr.. Herengrachl 365. Amsterdam, Holland, telephone 24.09.08.
Japan: Japan Printing News Co., Ltd., No. 13, 2 Chome Ginza Higasi, Chuo-ku. Tokyo, telephone [phone].
AUDIO Editorial and Publishing Offices, 134 N. 13th St., Philadelphia, Penna. 19107
Postmaster: Send Form 3579 to the above address
Check No. 2 on Reader Service Card
MUSIC GOES ON A RECORD ATA PERFECT TANGENT.
NOW IT COMES OFF AT A PERFECT TANGENT.
For years, Zero Tracking Error has been the They have confirmed that they can hear the
elusive goal of the automatic turntable maker. difference that Zero Tracking Error makes in
The objective: to develop an arm which would the sound, when the Zero 100 is tested against other
keep the stylus perpendicularly tangent to the top model turntables, in otherwise identical systems.
grooves... to each groove throughout the record, Until now, we cannot recall any turntable feature
because this is the way music is put on a record. being credited with a direct audible effect on sound
Garrard's Zero 100 is the only automatic reproduction. Usually that is reserved for the car
turntable to attain this. It is done with an ingeniously tridge or other components in a sound system.
simple, but superbly engineered tone arm. Through Zero Tracking Error is more than just a tech
the use of an articulating auxiliary arm, with pre nical breakthrough. It translates into significantly
cision pivots, the angle of the cartridge continually truer reproduction, reduced distortion and longer
adjusts as it moves across the record. record life.
The stylus is kept at a 90° tangent to the grooves... Once we had achieved Zero Tracking Error,
and the cartridge provides the ultimate JH we made certain that the other features of this
performance designed into it. turntable were equally advanced. The Zero 100 has
a combination of features you won't find in any
other automatic turntable. These include variable
speed control; illuminated strobe; magnetic anti-
skating; viscous-damped cueing; 15° vertical track
ing adjustment; the patented Garrard Synchro-Lab
synchronous motor; and our exclusive two-point
record support in automatic play.
The test reports by independent reviewers
make fascinating reading. You can have them, plus a
detailed 12-page brochure on the Zero 100.
Write today to British Industries Co., Dept. J12
Westbury, New York 11590.
GARRARD ZERO100
The only automatic turntable with
Zero Tracking Error.
The results have been recorded by experts in
their reviews of the Zero 100. Some of them are
saying things about this instrument that have never
been said about an automatic turntable before.
$19995
less base and cartridge
Mfg. by Plessey Ltd. Dist. by British Industries Company
Circle No. 3 on Reader Service Card
fludiocllnic
Joseph Giovanelli
November
AM Bandwidth frequency of the transmitter assigned to
610 kHz. Notice, too, that the 610 kHz
Q. Under what circumstances can
AM stations broadcast to frequencies station will be transmitting a sideband
on 600 kHz. If, therefore, these two
higher than 5 kHz? If a 5 kHz tone will
stations were assigned to the same
Kit Building—Some hints and produce significant sidebands at plus or
market area, very severe interference
minus 5 kHz relative to the carrier fre
tips by Len Feldman would be produced if audio frequencies
quency, it seems to me that such instances
out to 10 kHz were transmitted by each
of "high fidelity" broadcasting must be
The Language of High Fidel rare. On the other hand, twice in recent station. However, the FCC never assigns
stations on adjacent channels to one
ity, Part 6 of Martin Clif readings I have come across passages
ford's Guide for Beginners which suggest that such a situation may market area. Stations would be spaced
30 or more kHz apart. Thus, the side
not be as rare as I think it is.— Gary
Roboff, Worcester, Mass. bands of which we spoke would not re
Binaural Sound by Billy G. A. The broadcast band is broken sult in interference between two stations
Brant down into segments, each of which is within a given market area. Of course,
10 kHz wide. While we have come to good radio receivers can and do detect
think of a broadcast station as being signals on adjacent channels. However,
Christmas Buying Guide
this is not a consideration of the FCC.
assigned to a specific operating fre
quency, this station actually occupies a Many of us have come to think that
Equipment Reviews Include: spectrum of frequencies lying above AM stations are assigned an audio
Revox A-77 Dolby Tape Re and below this assigned carrier fre bandwidth not to extend beyond 5 kHz.
corder quency. As you indicated in your ques This is not the case at all. In fact, the
Sony 2000F Preamplifier tion, the reason for this is that the audio rules of the Federal Communications
Fairfax FX-300 Speaker System frequencies produce what are known as Commission which cover AM radio
sidebands. If a 5 kHz tone is broadcast, broadcast transmissions say that a
the AM station will be transmitting its broadcast station shall not depart from
assigned frequency plus two additional a flat response by more than 2 dB be
frequencies, one 5 kHz above, and one tween 100 and 5 kHz, based on a mid-
W 5 kHz below the station's assigned band frequency of 1 kHz. This does not
carrier frequency. (These outer fre mean, therefore, that the broadcast sta
quencies represent the sidebands.) If we tion must curtail all frequencies above
consider two broadcast stations assigned 5 kHz or all frequencies below 100 Hz.
to frequencies 10 kHz apart, and if each The only stipulation the FCC makes
one is transmitting tones of 5 kHz. the with regard to the upper limits of audio
lower sideband of the station assigned response is that the band of frequencies
to the higher frequency and the upper between 15 and 30 kHz must be atten
sideband transmitted by the station uated 25 dB with respect to a signal of
assigned to the lower frequency will 1 kHz. Frequencies beyond 30 kHz must
each produce the same frequency side be additionally attenuated.
band signal. Therefore, if it were possible to design
For example, one of the stations a filter so sharp that within the space of
might be transmitting on 600 kHz; the 1 kHz a 25 dB attenuation could take
other one on 610 kHz. With each station place, the AM stations could produce
transmitting a 5 kHz tone, the station frequency response flat right out to 14
broadcasting on 610 kHz will be pro kHz. Of course, 15 kHz would then have
ducing sidebands of 605 and 615 kHz; to be attenuated by 25 dB, placing strin
About The Cover: Cassette the station transmitting on 600 kHz will gent demands on such a filter.
recorders have come a long way produce sidebands of 595 and 605 kHz. You can see from all of this that a
Note that both have sidebands of 605 broadcast station is free to broadcast
during the past two years or so.
The first models could hardly kHz. audio frequencies considerably in excess
reach 7 kHz but the present-day If now, we take our same two trans of 5 kHz; probably a realistic limit is
contenders can reach 15 kHz mitters and transmit a 10 kHz tone on 10 kHz.
with ease. And with low wow each, the situation will become even
and flutter! However, open-reel more interesting. The station transmit
machines still have many ad ting on 600 kHz will be transmitting, in
addition to this frequency, sidebands of If you have a problem or question on audio,
vantages for the enthusiast; our
recent tape competition brought 590 kHz and 610 kHz. The station write to Mr. Joseph Giovanelli, at AUDIO,
134 North Thirteenth Street. Philadelphia,
in 446 tapes and only five transmitting on 610 kHz will transmit
Pa. 19107. All letters are answered. Please
cassettes! frequencies of 620 kHz and 600 kHz.
enclose a stamped self-addressed envelope.
Notice that the sidebands from the 600
kHz station exactly fall on the center
AUDIO • OUR 25TH YEAR • OCTOBER 1972
The ADC-XLM ".in a class by itself."
That's the way Stereo Review described our XLM. High Fidelity head
lined their review, "Superb new pickup from ADC" and went on to say,
"...must be counted among the state of the art contenders." And Audio
echoed them with, "The ADC-XLM appears to be state of the art."
With the critics so lavish in their praise of the XLM, there's hardly any
necessity to add anything. Far better to let the experts continue to speak
for us.
Frequency response The cbs str-ioo test The XLM has remarkably low distortion in comparison
record showed lessthan±1.5dB variation up with others. Audio
to 20,000Hz. Stereo Review At 0.6 grams the distortion was low (under 1.5 per
cent). Stereo Review
...response is within ±2dB over the entire range. Audio
Frequency response is exceptionally flat. High Fidelity
Hum and noise The XLM could be instrumental
in lowering the input noise from the first stage of a
Tracking This is the only cartridge we have seen modern transistor amplifier. Audio
that is really capable of tracking almost all stereo discs
The cartridge had very good shielding against
at 0.4 grams. Stereo Review
induced hum. Stereo Review
The XLM went through the usual torture test at
0.4 grams (some top models require more than a
Price This would be a very hard cartridge to surpass
gram). High Fidelity
at any price. Stereo Review
The XLM is capable of reproducing anything found on
We found it impossible to attribute superior sound to
a phonograph record. Audio
costlier competing models. High Fidelity
Priced as it is, it is a real bargain in cartridges. Audio
Distortion Distortion readings...are without
exception better than those for any other model we've The Pritchard High Definition
tested. High Fidelity
ADC-XLM $50. ~
p-TT^UDIO DYNAMICS CORPORATION
fcfc A 1 Pickett District Road, New Milford. Connecticut 06776
I—^^^^- Check No. 5 on Reader Service Card
Dear Editor
D D D
AM Buff No. 1 . . . The use of high stability, close toler 20 dB pad is placed between mike and
Dear Sir: ance resistors, such as Corning type tape recorder input for loud level
How do you express demand for C32's. a glass-metal oxide type; situations. There will still be plenty
tuners with good AM performance? I Strong glass-epoxy PC boards on a of signal going into the tape recorder
have been looking for one ever since strong chassis with robust yet light alu to achieve good signal to noise ratio.
the days of E. H. (not H. H.) Scott. minum alloy materials, and finally Most of the newer machines which
I agree with Mr. Herbert's letter in Simple, effective, and bug-free circuits have only one level adjustment afford
with easy, razor-sharp adjustments. a simple way to achieve this end. The
your July, 1972 issue. Most people today
don't know how good AM can be and Joe Frandeka "auxiallary" input, meant for levels
those who do can do nothing about it St. Louis, Mo. of a volt or so (from pre-amps, tuners,
because no manufacturer now builds a etc.), is actually an attenuator which
quality AM tuner. Distorted Rock Recordings goes between this input and the micro
R. N. Servaas Dear Sir: phone amplifier stage. Thus, by plugging
Grand Rapids, Mich. In doing a bit of review work, I just the microphone into the aux input
noted a tape recording problem de instead of its normal input, the chances
AM is not, as commonly supposed, scribed in Herman Burstein's March, of overload are greatly reduced.
inherently inferior to FM in terms of 1970 Tape Guide section of audio. I Prof. J. Robert Ashley
bandwidth or distortion. In Australia, have just finished fighting the same University of Colorado
where there is no FM, wide-band, low Colorado Springs, Colo.
problem in a PA system and my ex
distortion tuners are used extensively.
perience might be helpful to many
However, AM is subject to electrical
it. 'erference, and there is not much room tapTeh ere pcorordbilnegm s diteusactiroibnesd. by Ben Miller Construction Suggestion
in the present AM broadcast band. (AM is excessive distortion in live tape re Dear Sir:
on VHF? Well, that would be a different Being a devoted listener to orchestra
cordings of rock groups. Burstein cor and classical church music, I like to
strtaovrye!l) gSreigant adliss taonnc ethse— bpraoraticduclaasrtly baaftnedr r1e)c Ttloyo l ishtiegdh trheec otrhdrieneg pleovsesli balte t hcea utasepse:, work on improvements and extensions
dark so the tuner bandwidth would have 2) poorly designed first stage of the of my stereo system. Thus, I would like
to be restricted to avoid interference to see articles on construction projects
tape recorder, and 3) overloaded micro which would improve an already good
eneffelsc. tIsn fEronmgl asntadt,i obnesfo oren tahdej aFcMen nt ecthwaonrk prahtohneer .t hIa wn othueld oethmepr htawsoiz.e reason #2 sound system or basic building blocks
was established, top-quality AM tuners The problem is created by the high to up-grade or build a system.
had to have 9 kHz whistle filters or sound level of rock music performances My personal need is an 18 dB per
variable-bandwidth controls and the net and is similar to the PA system problem octave crossover at 300 to 500 Hz and
result was often pretty poor. Ana how when the entertainer or lecturer "eats also at 3000 to 8000 Hz to be used with
about stereo. It can be transmitter! on the microphone." A good dynamic Altec Lansing or University high fre
AM but ... . quency horn and a Klipsch type low
microphone can put out (at the secon
Having said all that, it must be con dary of the transformer) about a volt frequency horn. This is simply a sug
ceded that many AM/FM tuners have gestion, though I can well imagine that
(that's right, a whole volt) under these
low sensitivity AM sections. For instance, conditions. Usually, this is applied to many hobbists have a similar require
I like to listen to the news from Canadian the input of a transistorized stage di ment.
AM stations, but I get better reception F. Machmuller
rectly and the output of this stage fed
from my car radio than I can from quite to the level control. For normal levels, Kalthof, Germany
expensive tuners!— ED. this is the best arrangement because
the level control cuts out pre-amp noise Miklos Rozsa Society
And No. 2 when the level control is at a low set Dear Sir:
Dear Sir: ting. But, when the microphone signal There has been increased interest of
I read David P. Herbert's letter (July, hits a volt, the distortion is gross and late in the music of Dr. Miklos Rozsa,
1972) with great interest. It would in no tinkering with the level controls will both the music he has written for films
deed be nice to see quality AM tuners make the least bit of difference. and that he has written for the concert
with quality specs, features, and com This explains why Miller's recordings hall. Inasmuch as some of us feel that
ponent parts. Mr. Herbert has done from a large barn-like auditorium had his music is unjustly neglected, we have
audio science a great service with his less distortion. The sound intensity was founded, in his name, the Miklos Rozsa
letter. The only problem is that his less because the same acoustic power Society, the main purposes of which are
comments will most probably be ig radiated by the rock performers had to promote his music and to dissemi
nored! Let's hope not. to fill a larger volume and supply the nate news and information about it to
Besides the four items Mr. Herbert losses at a much larger surface area. music lovers. Those interested in such
recommends, I'd like to see the follow This meant the microphone output a society may write: J. F. Fitzpatrick,
ing: was lower and overloaded the input 2604 Davidson Ave., Bronx, N.Y. 10468.
Fully shielded, regulated, and filtered stage by less. If you would print this notice in your
power supplies; What is the cure? Probably the letters column, we would be most ap
The use of polystyrene capacitors of simplest is to wire up a 20 dB attenuator preciative.
high tolerance (Mallory had nice 2.5% with cable connectors which match the Mark Koldys
units); microphone connectors being used. This Dearborn, Mich.
AUDIO • OUR 25TH YEAR • OCTOBER 1972