Sept - American Radio History
SEPTEMBER/1964
60¢
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component quality in
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VOL. 48,
SEPT., 1964
Successor to
RADÌO,
No.
9
13 in a series of discussions
by Electro -Voice engineers
Number
Est. 1911
C. G. McPROUD Publisher
4 AUDIO
CURVING
THE
Editor
DAVID SASLAW
COLUMN
JANET M. DURGIN
JOHN R. GILLIOM
Production Manager
Representatives
Bill Pattie & Associates,
4761 West Touhy Ave.,
Lincolnwood 46, Ill.
James C. Galloway,
6535 Wilshire Blvd.,
HENRY A. SCHOBER
Business Manager
SANFORD L. CAHN
Advertising Director
Los Angeles 48, Calif.
Warren Birkenhead, Inc.,
No. 15, L- chome, Shiba Hamamatsu -cho,
Minato -ku, Tokyo, Japan
EDGAR E. NEWMAN
Circulation Director
Contributing Editors
EDWARD TATNALL CANBY
JOSEPH GIOVANELLI
HAROLD LAWRENCE
CHESTER SANTON
HERMAN BURSTEIN
BERTRAM STANLEIGH
AUDIO
Automatic Speaker Connector 19
Transient Generators For Audio Testing 22
A Note on Curve Plotting 24
1ITRI: R & D For the Tape Industry 26
A Basic Course in Commercial Sound,
Chapter 6 35
Hi Fi and the British: Privacy 38
8
40
44
Articles
center front position, and a vertical pattern narrow enough to direct almost all of the radiated
sound toward the audience. An increasingly popular solution to this problem has been the use of
columnar loudspeakers, whose length contributes
to narrow vertical dispersion.
Ronald L. Ives
John L. Grauer
Virginia Rettinger
Robert Angus
It is difficult, however, to maintain the desired
vertical pattern at high frequencies with conventional column speakers. If all the speakers in the
line operate at high frequencies, the pattern becomes extremely irregular due to phase cancellation. If only a few of the speakers are used in an
attempt to improve the pattern, high frequency
efficiency and power handling are degraded.
Norman Crowhurst
Alan Watling
Chester Santon
Edward Tatnall Canby
Bertram Stanleigh
AUDIO
Ampex Stereo Tape Recorder
Barker & Williamson Distortion and A.C.
Volt Meter
Heathkit Regulated Power Supply
These difficulties were overcome by Electro -Voice
engineers with the introduction of the line radiator-essentially a curved column. At high
frequencies each speaker radiates into a small
sector of the total coverage angle, with a minimum of phase interference from other speakers.
Using this technique, a vertical pattern is obtained which has nearly constant width and no
significant lobes at any frequency.
Profiles
46
Model 2070
46
48
Model 410
Model IP -20
Line radiator loudspeaker systems have one other
invaluable feature: there is very little sound
energy radiated off the end of the line. Thus, if
a line radiator is installed so that the long axis
of the cabinet points toward the microphones
used with the system, the best possible rejection
of acoustic feedback is obtained.
AUDIO in General
Audioclinic
Letters
Audio ETC
About Music
Editor's Review
Tape Guide
New Products
New Literature
Industry Notes
Advertising Index
e,.
s
2
Joseph Giovanelli
6
12
14
16
Edward Tantall Canby
Harold Lawrence
32
52
Herman Burstein
The ideal location for a line radiator in an auditorium, for example, would be above and in
front of the stage, with the radiating axis of the
system pointing slightly downward. Such an installation takes maximum advantage of the line
radiator's relatively broad, but tightly controlled
vertical distribution pattern to completely cover
the seating area from front to back at uniform
64
65
66
(title registered U. S. Pat. Off.) is published monthly by Radio Magasines. Inc., Henry A. Schober, President; C. G. McProud, Secretary. Executive
and Editorial Offices, 204 Front St., Mineola, N. Y. 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. Single copies 60t. Printed in U.S.A. at 10
McGovern Ave., Lancaster, Pa. All rights reserved. Entire contents copyrighted
1964 by Radio Magazines, Inc. Second Class postage paid at Lancaster, Pa.
Some of the most difficult sound reinforcement
problems occur in indoor areas plagued with
heavy reverberation, echoes, and similar ailments
caused by unwanted reflections of sound. In reverberant space it is particularly desirable to
direct all the acoustic power from the loudspeakers toward the audience, with as little power
as possible bouncing around in the space above
the listeners' heads.
An "ideal" loudspeaker for large reverberant
rooms would have a horizontal pattern wide
enough to cover the entire seating area from a
AUDIO Reviews
Light Listening
Record Revue
Jazz and All That
Loudspeaker Project Engineer
level.
For technical data on any E -V product, write:
ELECTRO- VOICE, INC., Dept. 943A
Buchanan, Michigan 49107
AUDIO
010
e
SigigereefeC
SETTING NEW STANDARDS IN SOUND
RADIO MAGAZINES, INC., P. O. Box 629, MINEOLA, N. Y.
Postmaster: Send Form 3579 to AUDIO, P. O. Box 629, Mineola, N. Y.
AUDIO
SEPTEMBER, 1964
Circle 103 on Reader Service Card
1
www.americanradiohistory.com
Coming
AUDIO CLINIC
Joseph Giovanelli
WWWWWWWIANII
Feud questions to
Construction
Electronic Organ Design.
Winthrop Pike. A pipe organ lover designs an electronic organ which satsifies
his exacting requirements.
General Audio
Live - Versus - Recorded
Techniques. Ed Villchur.
The man who has put on
more live- versus -recorded
concerts than anyone describes the technique.
Sound Reinforcement
A Basic Course in Commercial Sound. Chapter 7.
Norman Crowhurst.
Profiles
Harman -Kardon Citation
B
Stereo Amplifier.
E -V 644 Microphone.
OKI Stereo Tape Recorder, Model 555
:
Joseph Giovanelli
2819 Newkirk Ave.
Brooklyn 26, N. Y.
Include stamped, self- addressed
HF
envelope.
CH
CH 3
A Stereo and Derived Center
Channel System
CH
directional effect of speakers occurs at frequencies above about 850
cps, I believe, would there be objection to
using one (common) woofer for frequencies
below 350 cps and two mid -high -frequency
units for frequencies above. It seems to me
that in this manner better frequency response could be obtained by using one
good -quality woofer rather than two lesser
units. My proposed wiring of such a system
is shown in Fig. 1. Wiring for derivation
of a center channel is shown in Fig. 2. The
third, or center, channel could also be used
for an extension speaker. C. J. Hill, San
Francisco, California.
A. You certainly can obtain acceptable
stereophonic sound reproduction using your
scheme. (Your system is often used commercially.) The Ylow- and high -frequency
portions of your circuits would operate as
you specify, by using a woofer common to
both channels and separate high -frequency
speakers to give the directional effect. I
am not convinced, however, that the low
frequencies contribute little or nothing to
the stereophonic effect.
Further, you should be able to use the
fourth speaker as a derived full-range
center -channel speaker. (This is not a
third channel because it is derived from the
two existing channels. A third channel is
present when three separate recorded sound
tracks are used.) The impedance of the
fourth speaker, however, cannot be higher
than 8 ohms. The impedance of each of the
other speakers, then, must not exceed 8
HF
I
the Oct. Issue
On the newsstands, at
your favorite audio
dealer's, or in your
own mailbox.
CH 2
IND C
LF
HF 2
Fig.
2
C
2
Q. Since the
o
In
Common -bass connections. L and C
chosen for crossover at 350 cps.
1.
C
LF
FI
Fig. 2. Common -bass system with derived
center channel.
This speaker will probably reduce
the output from your system.
One more point to keep in mind is that
the woofer may be more or less efficient
than the other speakers in your stereo array.
If this does occur, you must compensate by
limiting the output of the more efficient
speakers with an L or T pad.
ohms.
Poor FM Tuner Performance
Q. My question concerns an FM tuner. I
live in an area in which there are many
powerful stations, and I have trouble with
multipath distortion. To cure the distortion
I bought a directional antenna and a rotator. With the antenna connected to the
tuner, there is a great deal of background
noise on strong stations. The noise is present on both monophonic and stereophonic
reception, but is particularly apparent on
stereo.
I constructed a SOO -ohm balanced pad
with a 5 -db loss which helped somewhat.
However, the pad reduces the signal
strength too close to the threshold of limiting on weaker stations. Disconnecting one
side of the antenna cures the noise problem, but also reduces the signal level, as well
as destroying the directional characteristics
of the antenna. Audio is clean except for the
background noise. The noise is similar to
interstation hiss, or white noise. Also, with
the new antenna, the stronger stations
splatter all over the dial. Some stations can
be found as far away as 10 me from their
proper places. Other than the splattering,
the tuner tracks properly. William A. Sasek,
San Leandro, California.
A. The description of the sound produced
by your tuner does not read like multipath
distortion. The sound of multipath distortion is similar to a severe case of inner
groove distortion on phonograph records.
It is possible that your tuner is not operating properly or that it is simply incapable
AUDIO
SEPTEMBER, 1964
nas just published a
new edition of the Comparator Guide.
If you are interested in understanding
the latest developments in record
playing equipment in order to select
the unit that best meets your individual requirements, you'll find this
booklet particularly useful.
We'll be glad to send you a complimentary copy. Just mail tie coupon.
-1
r--
Garrard, Dept. GM -14, Pert Washington N.Y.
Please send the new Gerrard Comparator Guide.
Name
Address
State
City
Zip Code
Circe 104 or Reader Service Card
www.americanradiohistory.com
the best seat in the house...
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Broadcasting authorities agree that an outdoor antenna is
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A FINCO FM antenna will deliver a clean undistorted
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of good performance when subjected to
strong signals. The "splattering" you have
noted indicates that the front end of the
instrument is overloaded or has insufficient
selectivity to suppress spurious responses.
Further, it is possible that the oscillator is
"squegging" on strong signals. (This means
that the oscillator, rather than producing
its local signal at a steady rate, is oscillating for a portion of a cycle and then ceases
oscillating for a period of time. The effects
of this on receiver performance will be
very similar to that which you have described. To cure this, you might check the
oscillator grid bias resistor. If its value is
too high, squegging will result.)
To be certain, obtain a tuner which you
know is working properly. Connect this
tuner to your antenna. Note its performance. If the second tuner performs poorly,
you probably do have some multipath
trouble in addition to the front end trouble
with your own tuner.
It is possible that your location is very
close to the FM station you wish to hear.
If that is true, possibly the tuner is not as
much to blame as I suspect. The directional
antenna will then introduce a tremendous
amount of signal into the tuner. This signal will overload the tuner. Tuners which do
not provide age to their front ends are especially susceptible to this kind of trouble.
There has been a considerable rise in
popularity in the use of superregenerative
receivers, both for the Citizen's Radio Service, and for the Amatuer Radio Service.
Such receivers radiate a wide spectrum of
energy for a block or more. This radiated
energy sounds very much like white noise.
This, then, may be the source of your background noise.
Try adjusting your antenna for best signal quality, rather than for maximum signal
strength. If your trouble is caused by front end overload, reducing the signal strength
will relieve it, assuming that repositioning
of the antenna does not introduce multipath
distortion.
If it often happens that you wish to listen
to weak stations, discard the 300 -ohm balanced pad you discussed in your letter. The
purpose of the pad was to reduce the
strength of local signals, but, as lias been
indicated, this same effect can be produced
by rotating the antenna away from the desired signal.
To obtain the weakest possible signal, the
antenna should be rotated 90 degrees from
the direction of maximum signal strength.
If the antenna is rotated 180 degrees from
maximum signal strength, the signal will
build up once again, but the strength of this
signal will be considerably less than when
the front of the array is pointing to the
transmitting station.
(Continued on page 55)
SUPPORT
YOUR
MENTAL
HEALTH
ASSOCIATION
AUDIO
SEPTEMBER, 1964
HERE'S WHY JOHN C. KOSS BOUGHT
CONTROL OF REK -O -KUT CO. INC.
We've been asked "What's the connection between headphones and turntables ?" The
answer lies in devotion to the very finest in sound reproduction. As primary developer
of high fidelity stereophone listening, Koss produced the very standard of the headset
industry. Koss Electronics still labors toward the finest in sound reproduction. And so
Rek- O -Kut, producer for over a quarter century of the standard of quality in record repro-
-
is a
-
the standard demanded by recording studios and radio stations
product Koss can proudly produce.
duction equipment
REK-O -KUT B -12H TURNTABLE $165.00
flutter: 0.085% RMS.
Three speed. Noise level: -59 db below average recording level. Wow and
and
"hush" performance.
speed
for
constant
motor
Synchronous
Hysteresis
Custom -built, heavy duty
On -off signal indicator.
KOSS PRO -4 STEROPHONES $45.00
cps. Impedance: 50 ohms to be
a professional instrument. Frequency response: 30- 20,000
over long
used with 4, 8, or 16 ohm outputs. Fluid- filled ear cushions for positive seal and comfort
Truly
unusulistening periods. Highest quality drivers mounted in acoustically designed chambers provide
ally smooth frequency response. Equipped for boom mike attachment.
KOSS
REK-O-KUT
2227 N. 31ST STREET
MILWAUKEE 8, WISCONSIN
WRITE FOR COMPLETE DETAILS AND SPECIFICATIONS
ON ALL KOSS AND REK -O -KUT PRODUCTS
Circle 106 on Reader Service Card
AUDIO
SEPTEMBER, 1964
5
www.americanradiohistory.com
LETTERS
Our new collection is now
available
...
equipment cabinets
speaker
enclosures
cabinets
consoles
galore. Danish and Provincial
styles in new decorator finishes.
see your dealer or write for free brochure
"Simplicity" Color Code
Pike Disputes Electronic Shaver
SIR
SIR:
:
"Ticky Tacky Wires," indeed! Cable and
wire color- coding is simplicity itself, if
cable and wire people would only adopt Ma
Bell's standards, which have been in the
public domain for years. All you need remember are five colors: Blue, Orange,
Green, Brown, Slate. Numbers one to five.
Number 6 becomes B- White, 7 is B -O, 8 is
B -G, 9 is B- Brown, 10 B- Slate. Then it
starts all over again: O -W, O -G, O -S: G -W,
G -Br, G -S: Br -W, Br -S, and number 20 is
Slate -White. Pairs 1 to 20 have white mates,
21 -40 have Red Mates, 41 -60 have Black
Mates, and so on. Single Conductors are
either plain (colors only), or have Red,
Black, or white "novelty" (sort of a dotted
effect) tracers.
What can be simpler t
By using the basic 20 color combinations
and bundling the conductors into 20 pair
complements (or singles) with a light wrap
of colored cord, 20 x 20 pairs are possible
in a single cable without any problems in
locating any pair. (First 20 in Blue wrap,
2nd 20 in Orange wrap, so on). You
simply cannot beat this system of color coding wires. The only puzzling thing to
me is the idiotic and non -standard assorted
systems that most wire manufacturers use.
No two systems alike.
Another Bell System standard we might
adopt is "RED- Ring- RIGHT." In inside
wiring, (R -G -Y) Red is the Ring side,
Green, Tip, and Yellow is ground. I mark
Right side cables with red fingernail polish
-Red, RIGHT. The unmarked cable is
Left (taped to the R side cable). Dots of
model airplane dope, according to the WE
color code, mark cables for their destination, numbered in order. Blue- number 1,
Or- number 2, and so on. Red dot or plug
skirt is the right side. You can't get much
simpler than that!
FREDERICK C. HERVEY
audio originals
546
S.
Meridian
Indianapolis, Ind.
Supervisor, WHKW
Rt 3 (Quinney Rd)
Chilton, Wisconsin
(Maybe we can't get simpler for telephone
repairmen -but we had better get much
simpler for music system users. En.)
No Name -No Sound
SIR:
I read the editorial "No Name -No
Sound" with considerable interest. I believe editorials of this kind are in the
best interest of our industry as a whole,
consumer -manufacturer- dealer publications included.
R. V. PEPE, Vice President
JBL International
3249 Casitas Ave.
Los Angeles 39, Calif.
SIR:
I'm very happy to see publications take
a definite stand on subjects of controversy.
Only in this way can the consumer
through the knowledgeable person -get
the true facts on any product, as well as
get the word on a sham product. I extend University's heartiest congratulations.
CHARLES W. OVERSTREET
-
Advertising Manager
LTV University
9500 West Reno
CIRCLE 107
6
Oklahoma City, Okla.
Certain points in Mr. Shaver's letter are
worth answering, though the discussion provoked by my paper must, one hopes, end
sometime.
First, there is no reverberation system
on my organ, though I have long contemplated concocting one. There's little doubt
that it would help, as the room is small
(2300 cu. ft.) and relatively "dead." At
least one commercial installation of an electronic reverberation system has been made
by the Aeolian -Skinner organ company to
improve the sound of one of their pipe organs which suffered from a particularly
non -reverberant environment. From all reports it is eminently satisfactory.
For practice purposes, however, a "dead"
room is not without its uses. Each faulty
trill, rhythmic defect or finger slip is mercilessly revealed and when one has learned
to play a given work convincingly under
these circumstances, playing it on a different organ in a more reverberant environment is appreciably easier. Like spinach,
it's good for one.
There are many who would not dub me
a purist. For example, I dislike two of the
currently fashionable (in some circles) fads
intensely: tracker action and "ehiff."
Though most electronics do indeed sound
better than harmoniums they do not, as a
rule, sound better than pipe organs. In fairness to the electronics, however, I must
report that I have heard two installations
which were indistinguishable from excellent
pipe organs. Both were expensive instruments with many ranks of oscillators. If
this be heresy make the most of it.
Third, I did not mean to say or imply
that "the imperfections such as the finite
time it takes for a pipe to speak" are virtues. My point was and is that these characteristics inherent in the pipe organ are
ignored in many electronics -one of the
reasons why the latter sound different.
Last, I fail to follow the reasoning behind Mr. Shaver's statement: "if we carried
his 45 different attack time to its logical
conclusion we would go back-to a completely pneumatic pipe organ with no relays." What have the relays got to do with
all this! In general the type of action used
in a pipe organ, while in some eases (tubular pneumatic action) having delays of its
own, does not affect the actual pipe attack
times nearly as much as other factors (wind
pressure, nicking, foot hole size, lip and
languid adjustment). Aside from these
technicalities, differing attack times as
functions of pitch and timbre seem to be
virtually immutable natural phenomena.
Low-pitched pipes always start more slowly
than high -pitched pipes. Pipes of certain
classes of tone are consistently characterized by a different range of attack times
than those of other classes. In the best electronics these naturally occurring relationships are deliberately preserved by appropriate (and expensive) circuit design. In
the cheaper electronics this cannot be done
for purely economic reasons.
WINTHROP S. PIKE
101 Leabrook Lane
Princeton, N. J.
To cure more, give more
AMERICAN
CANCER
SOCIETY
AUDIO
o
SEPTEMBER, 1964
WE DARE TO COMPARE
THE CONCERTONE
800
FEATURES:
6
HEADS
3
MOTORS
0-
111111
Mil
MEE
BEINEENIEHEIE
111111111111111
AUTOMATIC REVERSING
FOR RECORD & PLAY
PUSH BUTTON
CONTROLS
REMOTE
CONTROLLABLE
SOUND ON SOUND
BUILT-IN
ECHO CONTROL
CENTER CAPSTAN
DRIVE
onomomomonoon
IIIREEIBIEREIME
1111111111111111111111.111
comminnommalm
TRANSISTORS
onamammomomom
TAPE LIFTERS
OPERATES BOTH
HORIZONTAL
VERTICAL
&
COSTS UNDER $400
One look at the chart above should prove to
your satisfaction that the Concertone 800 is your
(portable or tape deck) is realistically priced. It
starts at $379.95 (including two dynamic
best value in stereo recorders!
microphones for stereophonic recording).
What the chart does not show you is that
Concertone's industry exclusives double
If you are still not convinced we dare you to
send for the clincher -our new brochure on the
Reverse- o- matice' (automatic reversing at each
Incomparable Concertone 800, and the name of
your nearest dealer. Write to Concertone, Post
-
end of the tape), and six heads
- combine to
Monte, California.
give you continuous music playback and record-
Office Box 3162, South
ing with the touch of a button.
And if that is not enough, the Concertone 800
CONCERTONE
Circle 109 on Reader Service Card
AUDIO
SEPTEMBER, 1964
www.americanradiohistory.com
El
e
LIGHT LISTENING
Chester Santon
Frederick Fennell: Broadway Marches
Mercury SR 90390
This recording is part of Mercury's fall release schedule but it was a warm evening in
early summer when I attended one of the
three recording sessions that brought it into
being. The invitation to visit Bob Fine's recording studio in a former ballroom of New
York's Great Northern Hotel had been ex-
-
tended by my colleague in these pages
Harold Lawrence-in his non -spare time a
recording director for Mercury Records. Frederick Fennell's latest recording session had
on its agenda a program of marches from
leading Broadway musicals to be played by a
sizable group of top instrumentalists taken
from New York's pool of free -lance recording
musicians. The orchestra (no strings but
heavy in brass, winds and percussion) was
spread out in a thin semicircle that filled one
half of the converted ballroom. Although
lower in ceiling than most ballrooms of its
size, the studio at the Great Northern is a
very live one. Therein lies the saving grace in
a session that exceeded any other I've attended in closeness of miking. Gradual
changes in the other links in the stereo disc
recording process now permit proximity in
mike placement that would have been out of
the question a few years ago. Just about every
instrument at this Fennell session had its
own Telefunken or RCA 44 boomed above it
at a distance of only two or three feet. The
condensers were on winds, accordion, banjo,
guitar and percussion with the ribbons assigned to the special problems generally
created by trumpets and trombones at so
short a distance. As at most sessions run by
a practical crew, the criterion for determining the best sound of the orchestra was the
playback of the master tape as soon as a
satisfactory take had been completed. Since
recording engineer George Piros was driving
the three Altec monitor speakers at full volume during each take, the slightly lower signal level in tape playback (coupled with
tape's normal attenuation above 15 kc) gave
a more realistic picture of the orchestra than
did the live monitoring. From my vantage
point just to the right of the recording director it was easy to see that one source of tension for the recording engineer had been
eliminated in today's sessions. The three VU
meters were allowed to peak at some distance above the once -sacred zero mark.
Some weeks after the event, Harold Lawrence made available to me test pressings derived from the session for evaluation on my
own equipment. Stereo separation is more
pronounced on my home setup than It appeared in the control room. Test pressings
having a slightly better high -end response
than the commercial product, the sound on
disc is remarkably close to my memory of the
master tape playback. As for the contents of
the album, seekers of the conventional in
show tune arrangements are advised to look
elsewhere. In many of the selections, this
recording is a pretty uninhibited affair.
Ranging over a wide span of Broadway musicals, the album has many highlights a rousing version of Gershwin's Strike Up the Band
with generous quotations from the band
literature, a steamboat whistle and pistol
shots during a Stephen Foster medley and a
truly unbuttoned treatment of Nothing Like
A Dame from "South Pacific." The best sound
by the full orchestra is found in 76 Trombones while top audio honors go to the percussion section in The March of the Siamese
Children.
:
8
Fade Out -Fade In (Original Broadway
Cast)
ABC -Paramount OC 3
ABC is really rolling ahead in what appears
to be a major invasion of Broadway show
recordings. Hard on the heels of its excellent
"High Spirits" original cast album, ABC Paramount scores again with this tribute to
the Hollywood musicals of the 1930's. Just as
Beatrice Lillie stole the "High Spirits" album, Carol Burnett corrals most of the honors
(comic as well as musical) in "Fade Out
Fade In." She's got a lot to work with in fine
songs by Jule Styne and biting lyrics by Betty
Comden and Adolf Green. Years of television
-
appearances have not dulled Miss Burnett's
appetite for zesty material and zesty material
is precisely what she's blessed with throughout this enjoyable musical. It is hardly necessary to remind TV fans that no department
of comedy holds terrors or problems for Carol
Burnett. Her conquests in this field belie the
fact that her first New York appearance was
made only five years ago in the musical
"Once Upon a Mattress." In her latest main stem musical, Carol Burnett plays the part
of an ex-movie usher who is catapulted to
stardom in the wacky world of an earlier
Hollywood. A solid succession of songs (The
Usher from the Mezzanine and Lila Tremaine), delivered with verve and comic ingenuity by Miss Burnett, chronicle the transformation of Hope Springfield into the glamorous Lila Tremaine. Call Me Savage and a
poignant Go Home Train add to the Burnett
laurels. Jack Cassidy, one of the busiest actors of the past season, is a reliable foil as
her leading man. The broadest slice of comedy
in the show is the Burnett song and dance
impersonation of Shirley Temple in the deadpan lyrics of You Mustn't Be Discouraged.
Add to all this the bonus of truly outstanding audio work and you have a very nice record on your hands.
Skitch Henderson
Bronjo BR 105
Prominent pianists in the light music field
are turning up in the most unexpected places
these days. Did you know, prior to scanning
the top of this review, that Skitch Henderson
is now recording for the Bronjo label, a division of Seeco Records? Connoiseurs of truly
tasteful piano work will find this release
worth all the effort involved in searching for
it. The dozen selections are split three ways
for top tunes by Cole Porter, Richard Rodgers
and Jerome Kern. The pressing is a noisy one
at anything approaching normal volume yet
the performance by Henderson and his small
combo can be recommended to the hilt for
low -level, late evening listening.
World's Fair Suite
RCA Victor LSC 2764
Ferde Grofe's "World's Fair Suite" is now
available in its official recording with noted
bandmaster Paul Lavalle leading the World's
Fair Symphony Orchestra. Its five sections
attempt to capture, in familiar Grofe style,
such features of the Fair as the Unisphere,
the International section, the industrial pavilions and the merriment originally planned
for the Amusement area back in 1961 when
World's Fair President Robert Moses invited
Grofe to tackle the assignment. The music
Grofe Suites such as "Grand Canyon" or
cannot be mentioned in the same breath with
others but it will do as a souvenir of the fair.
Weill Classics: Lady in the Dark /Down in
the Valley
RCA Victor LPV 503
It would seem that Columbia Records' recent decision to renew our acquaintance of
Burt Well's "Lady in the Dark" with a mod
ern recording has reminded RCA that the
vaults have contained music recorded many
years ago by the show's original leading lady.
Where Columbia tried to revive memories of
the 1941 production through the fine voice
of Rise Stevens, RCA bolsters its newly -an-
nounced Vintage series with the voice of Gertrude Lawrence heard in the part she created
when the show opened on Broadway. The
historic value of this RCA theater recording
cannot be questioned but the reissue is no
more than a sampling of the score as compared to Columbia's revival of "Lady in the
Dark." The Rise Stevens production takes up
both sides of the record, offering a comprehensive coverage of the music by the principal members of the cast. This RCA reissue, occupying but one side of the disc, is devoted
almost entirely to Miss Lawrence's songs. The
sound is antiquated but not quite enough to
bother anyone really curious to hear the
original concept of a musical role that broke
with theatrical tradition.
"Down in the Valley," Kurt Weill's one -act
opera based on familiar American folk songs,
takes up the rest of the disc and features the
cast that presented the work as the first
opera to be telecast on the NBC Opera Theatre, January 14, 1950. Since the recording
was made only eleven days after the telecast,
the sound on this side of the disc is far superior to that of "Lady in the Dark."
The Great Isham Jones and his Orchestra
RCA Victor LPV 504
The next time you happen to find yourself
arguing that the years of the Thirties were
the golden days of the big dance bands whip
out this exceptionally fine reissue in RCA's
new Vintage Series. Just about everything
you'll require to make your point can be
found in these solid arrangements by the
famous Isham Jones and his orchestra. The
Jones band was a rather unique institution in
dance circles from 1919 to the mid- 1930's.
Before joining the Victor label, Isham Jones
was one of the big attractions of the old
Brunswick Record Company. (By 1923 he had
received over $500,000 in royalties from
Brunswick.) Not only did Jones write over
200 songs, many of them still in use today
he was the first to sense that "Stardust"
would make a fine ballad some two years after
it emerged on the music scene as a wordless
bit of ragtime. Anyone who listened to the
great radio bands on the receivers of the
day will certainly appreciate RCA's gesture
in reissuing on LP the Isham Jones 78's that
had been stashed away in their vaults. Here,
in surprising good sound, is a chance to relive the days when Chicago was the home
base of dance bands such as Hal Kemp, Bob
Crosby and the Coon-Sanders group. The
selections presented here cover a period of
twenty -three months (August 17, 1932 to
July 16, 1934) and include sides from Isham
Jones' first and last RCA Victor recording
sessions. I find them a very pleasant way to
relive history.
-
Martha Schlamme /Will Holt: Kurt Weill
Cabaret
M -G -M SE
4180
This is a generous sampling of the off Broadway cabaret performance that made
such a hit with Kurt Weill fans when it opened
last year just off the Bowery. In the stage
production, a beat -up gilt piano and two
dusty bar stools were the main props as Martha Schlamme and Will Holt introduced and
sang excerpts from famous as well as lesser
known Weill shows. The extensive folk music
background of both singers is a great advantage when it comes to recreating for the home
listener the period of pre -World War One
Germany that Weill mirrored so uncannily in
his biting songs. For a native of Portland,
Maine, Holt does an effective job of keeping
up with Miss Schlamme who, of course, has
the advantage of Austrian birth in breathing
life into these highly European creations.
AUDIO
SEPTEMBER, 1964
Before
multiplex came along,
you could get by
with an average tuner.
Now you need
Fisher.
Nis
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The new, transistorized Fisher TFM -300.
Size: 151/4" wide, 41%6" high,
In the good old days of strictly monophonic FM, any reasonably well -engineered tuner brought in at least your local
stations with listenable fidelity. Of course,
a Fisher tuner still made quite a difference
in sound quality; but it was a difference in
degree, not in kind. Multiplex has changed
all that.
Even though FM-stereo has potentially
much greater sonic realism than FMmono, a multiplex broadcast can actually
sound badly distorted unless received
through an absolutely first -rate tuner. And
to hear a stereo program exactly as it was
monitored in the FM station's control
room requires the sensitivity, wide -band
117,43"
deep. Weight: 9 lbs. Price: $299.50.
design. low distortion and unequaled
channel separation of a Fisher multiplex
tuner. Nothing less will do; the medium
itself has become more demanding.
The seven stereo tuners currently made
by Fisher all feature ultrasensitive front
ends, either five or six wide -band IF stages,
either four or five wide -band limiters,
wide -band ratio detectors, multiplex circuitry of the superior time -division type,
and automatic mono -stereo switching via
the Fisher STEREO BEACON *. The IHF sensitivity of all models is in the range from
1.8 to 1.5 microvolts; FM- stereo separation at 1 kc ranges from 35 to 40 -plus db.
Prices start at $249.50, less cabinet. .",=,G
OVERSEAS RESIDENTS PLEASE WRITE TO FISHER RADIO INTERNATIONAL. INC..
LONG ISLAND CITY, N. Y.
11101.
CANADIAN RESIDENTS
FREE! 52.00 VALUE! Send
for your free copy of The New
Fisher Handbook. This entirely
new, revised and enlarged edition of the famous Fisher high
fidelity reference guide is a
magnificent 76 -page page book.
Detailed information on all
Fisher components is included.
Fisher Radio Corporation
44th Drive
Long Island City, N. Y. 11101
THE NEW
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AUDIO
9
SEPTEMBER, 1964
www.americanradiohistory.com
In Love
Norrie Paramor: In London
Again
Capitol ST 2071
Norrie Paramor hasn't had an easy time
establishing a reputation in this country because the leading record catalog doesn't list
him in the section where most record buyers
would normally look for a popular orchestra.
His group has been held in high regard by
knowing collectors since 1956 yet the outfit is
not listed in the "Popular" section of the
catalog. Instead, Paramor pays a price for the
authenticity of his English style of music
making by being listed solely in the catalog
section marked "Popular -Other Countries."
There, under the "England" heading, he occupies the most prominent listing with nine
releases, along with Ray Noble, Jack Hylton,
Frank Cordell and such esoteric phenomena
as the "Original Soho Skit& Group." The
Paramor strings, aided by an unusually full throated piano, happen to be one of the very
rare ensembles to merit the use of the word
luxuriant in describing their sound. What's
more, the exceptional nature of the sound is
on this disc where an expensive system can
actually make use of it. The selection of music
in this recording is in a class with the sound,
giving Capitol a stereo disc that any company interested in quality would be proud to
call its own.
.
KENWOOD
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America,
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Meet the new KENWOOD chassis designed for connoisseurs with all -new circuitry engineered only for
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KENWOOD's first consideration is quality. (You might
also be interested in KENWOOD's minimum price.)
KENWOOD features that make the difference
KW -550 FM AUTOMATIC STEREO MULTIPLEX TUNER
Automatic relay switching to proper mode Exclusive FM
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muting circuit Built -in noise filter Low impedance cathode follower output Stereo and mono outputs Tape recorder
terminals Retail price $169.95
KW-220 INTEGRATED STEREO AMPLIFIER
Total 100 watts music power or 50 watts per channel (IHF
Standard) Thirteen front panel controls Two sets of terminals for each MAG and AUX Tape monitor switch DC filaments for minimum hum and noise Front panel stereo headset jack
Front panel speaker off /on switch
Use with any
components Retail price $169.95
Visit our exhibit at San Francisco High Fidelity Music Show,
San Francisco Hilton -Room M.
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KENWOOD ELECTRONICS, INC.
3700 S. Broadway Place, Los Angeles, Calif. 90007, AD 2 -7217
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.
Hear You Singing
Reprise FS 2020
Where once the Reprise outfit was content
to launch a record merely on the talents of an
individual star, it has lined up a pretty impressive cast for one of its latest projects.
The title of this album has perhaps already
told you that this is one of those Be -GladYou're-An- American epics featuring the kind
of music you are apt to hear when a travelog
film on the U.S.A. reaches its climatic moment. Reprise comes up with the predictable
stuff for chorus and orchestra. The surprise is
in the choice of featured performers. To keep
the business from getting too pumpous, Bing
Crosby and Frank Sinatra are starred in the
solo positions with Fred Waring's organization bringing up the heavy artillery. Seven
arrangers were brought into the undertaking
to lend diversity to typical Americana such as
The Hills of Home, This Land is Your Land
and Stars and Stripes Forever. The combination of talent should find a ready market, even
among those who don't normally make an
effusive display of their patriotism.
I
Richard Tucker:
Dreams
Vienna,
City
of
My
Columbia MS 6537
One can sympathize with Columbia's efforts
to bring the glories of Viennese operetta to an
English speaking audience and still be less
than excited about the results. Richard Tucker's latest album turns out to be a handsome
and comprehensive collection of tunes, many
of them usually found only in the record
libraries of the operetta connoisseur. Two
things stand in the way of unreserved enjoyment of these delights of the Viennese stage
of decades ago. The English lyrics concocted
by Merl Puffer and Deena Cavalieri (they
supplied the libretto for the recent Columbia
recording of "The Merry Widow ") are one
problem. The other is the somewhat stodgy
approach to this gay music by Richard
Tucker. In ten of the thirteen selections recorded here, the team of Puffer and Cavalieri
has supplied new translations that demonstrate once more the virtual impossibility of
translating the gossamer magic of the original
lyrics into our own tongue. Under these circumstances, it's hardly Tucker's fault that he
occasionally sounds more like an oratorio
tenor than an operetta star. If you consider
the degree of fluid ease Tucker still manages
to bring to the immortal tunes of Lehar, Zeller,
Von Suppe and Strauss in these stiff translations, it's a pity Columbia didn't assign him
the original lyrics for his first Viennese
album. The Columbia Symphony under Franz
Allers lends velvety support to the rich
Tucker voice but the conductor finds it no
easier to handle some of the more awkward
phrases than the singer does.
1£
AUDIO
SEPTEMBER, 1964
SPECIAL PRE - PUBLICATION OFFER!
-
ORDER NOW
SAVE
20%
for this
PAY only
$2.80
volume
published at $3.50
NOW
-
At this time half past 1964
six anthologies of significant
reporting in the divers areas of
audio technology occupy the
bookshelves of thousands of AUDIO
regulars men and women in
all fields of American enterprise.
The six, a library of 250 meaningful articles, are a documentation
of the progress and development
of the audio art -the science of
recording and reproducing music
and sound.
-
-
And now, with the Seventh
AUDIO Anthology, we add to this
valuable reference work. The
important articles contained
in this volume appeared in
AUDIO in the past two years
1962 and 1963.
-
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O°°
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PREPUBLICATION ORDER FORM
ANTHOLOGY-RADIO MAGAZINES, INC.
P.O. Box 629 -MINEOLA, NEW YORK 11502
Enclosed is my remittance for $_
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Radio Magazines, Inc. reserves the right to withdraw this offer without notice.
www.americanradiohistory.com
ZIP CODE
cided, it says, to replace my FPHLOP -B
with an MNXX 29 and the AQZX -3 in
the Gyrogymbal 2A-3 into EX 99s. I
have already ordered these. I would like
your opinion. I would appreciate your
help in choosing my high fidelity system.
Thank you for your advise. Sincerely,
Joe Doe.
AUDIO ETC.
Edward Tatnall Canby
Thanks for nothing. friend, I mutter
N
HAN DLERY
It's a strange and rather pleasant
feeling, as I hit the typewriter once more,
not to have a single audio -idea in my
large, empty head. That's what comes of
time-off in this business-the so- called
double -sabbatical (plus three) that I've
been taking from this column. It would
have had its seventeenth anniversary this
last May, if I had been there.
Yep, I've been absent, though some of
our readers haven't yet noticed it, I
gather. Nigh -onto five months. Nope, I
did not have a heart attack and hereby
serve notice that I wish no more condolences and expressions of sympathy,
thanks -just- the -same! Look closely (AUDIO, June 1964, p. 12) and you'll discover that it was Norman Pickering,
founder of the great Pickering phono
cartridge enterprises, who had the heart
attack and was, happily, recovered
enough to write a June guest column for
us. Some of our more determined readers
insist on crediting me with Mr. Pickering's misfortune, as well as his excellent
article.
Yep, I did write the repeat columns,
in May and July. That is, I originally
wrote them, so to speak. And if some
happy readers took as 1964 gospel all
those things I said about small record
companies, as of a number of years ago
(AUDIO, May 1964) -then I must be
getting infallible or something. I found
the piece interesting to look at again
mainly because so much has changed
since then. More on that subject later on,
I hope.
Oh yes-that "Audio Year" (our July
issue. It wasn't this year I was describing. It was the 1953 -54 audio year, as of
ten years ago. Wonder how many people
noticed, as they read t
So here I am, live and current, writing
once more in '64, and what is most interesting to me about my own reactions
to no -audio for these months is my slipping memory. Memory, that is, for incidentals. Details, How soon they fade!
Fphlop-B
Oh I remember the big principles, all
right. But I tend to forget the handles.
We get so awash with handles in our
business, it's a wonder anybody has time
12
\'
for the fundamentals, though plenty
seem to.
You see, people keep right on writing
me every so often for hi -fi advice because I'm a "hi -fi expert" in some people's minds, if not my own. And in true
hobbyist fashion these people prefer to
talk the lingo. My correspondents take
pride in revealing to me their own knowledge of what it takes to be a hi -fi man.
They know all about current audio
terminology and I'm duly impressed, you
may he sure. I don't stand a prayer of
keeping up with them, myself.
Dear Mr. Canby, someone will write
(to concoct a concentrated example), I
am about to assemble a high fidelity system. (Oh yeah? You said that the last
time.) I would like your advise. (For
some reason, that is the usual spelling.)
My present system consists of (oh -ohhere come the handles
an AQZX -2
in a BGXBT aria and a SQWK Super
De Luxe feeding a SAP -3 and a
FPHLOP -B Mark II, 50 -50, into a pair
of XYZ 4Cs. (Humph, say I, that lust
must be speakers.) I use the SKRCH II.
Mark XXVI, with a GLRP 29BX array.
(Ah yes, antenna I suppose. I'm groping
for clues.) The FPHLOP -B also feeds
a Coronet DXLYMPNX Rondo Sonata
Superbo. (A tape recorder, maybe?
There isn't much else left.)
I would like your advise, the letter
continues. Please give me your opinion
on the exact performance of the AZ -3,
the Whillow, the Whssp, the Major, the
Corporation, the Baron, the President.
Also the Emperor III and Whomp Mark
V, also the Tweet, Jr. Also the speakers
in the following list see pp. 2 -4.
Also please specify the tube radiation
curves for the FPHLOP -B as compared
to the FPHLOP -D also the MNXX 29.
I would like your opinion. (On what,
...)
for goodness' sake? ?)
At that point, my head reeling, I dig
out the audio catalogues. Hmmm.. . .
(while my secretary waits with all her
usual patience) ; here's the FPHLOP -D
all right. It was an amplifier. Guess my
hunch wasn't so bad. No tube info. All
transistors, maybe? It says 20-20,000;
this must be an old catalogue. This year
it's 0- 1,000,000, isn't it?
The letter isn't over yet. I have de-
as I breathe a sigh of relief. It's not
merely that our fond readers tend to ask
us for advise (sic) when their minds are
already made up-or they don't intend
to do a thing except on paper. That is
an excusable enthusiasm, a normal pipe dreaming, an understandable wishfulthink ! I do it myself with my new car,
every two months by the calendar; and I
still have my '62 VW117, natch. One has
to plan. One must have advise, after all.
No-what gets me, after five months
of no- audio, is the handlery. I just can't
seem to remember whether it's the Jensen PAS -3 or the Dyna TF-4. Was it
the Sherwood 58000III, or maybe the
Harmon- KardanI I mean Karmon H
Wait a sec; That must be HarMAN
-.
KarDON. Keerect!
And how about the TA700X 1 Doesn't
seem to ring the right bell with me,
somehow. Or the X- 101 -C. Who belongs
to that one? I'm stumped. Nor can I
figure out the who or what of the 380,
the 222D and the 333B, the 654MA. Not
even the MR67. (That one sounds like
"Mister Audio of 1967." But what is it?)
Definitely, I can't figure the D51 -0012E/T. Took a master mind to concoct
that.
I couldn't figure these out, that is, if I
hadn't just taken every one of them
straight from a genuine hi fi catalogue.
They're for real. Nope. I don't have that
kind of memory.
(If I did, you see, there are all those
phone numbers and zip codes by which
I must identify not a mere piece of
audio equipment but MYSELF. Area
codes and audio too? It's just too much.
Even minus a dog tag I must keep in
mind that I'm known on the long -distance
wire as 2030R26085, or 1212CH36283,
zip code 06796 or 10014, as the case may
be. And don't even ask me my several
multi-digit bank account numbers. Or
my social security. That one, at least, is
firmly on file in the AUDIO office.)
So there you are. After five months of
absence, nothing in my head but figures
and letters, hopelessly jumbled. Not even
a suggestion as to what we might do to
unhinge this alphabet soup of audio terminology.
Forget it all? That's just what I did.
But, luckily for me, all the new 1965
catalogues have just arrived (06796).
So if you'll pardon me, I'll go quick and
bury my head in the sand.... D -it, I
mean in the catalogues! That's what I
Æ
said, didn't I?
AUDIO
SEPTEMBER, 1964
J'IBL PRESENTS THE
SOLID STATE STEREO
GRAPHIC CONTROLLER
A TOUR DE FORCE OF
CREATIVE ENGINEERING
Straight, ine controls. Pushbutton selectors. Inputs in front as well as
back. Take a look and wonder...lsn't this the way it should have been
done in the first place? The JBL design staff started fresh. Clean slate.
No restrictions, pre!udices or preconceptions. With cold objectivity
they regarded the functions of a preamplifier /control center, re- evaluated its relationship to a human operator; weighed every conceivable
-feature. Straightline controls give immediate visual indication of setting. Even from a distance. Direction of movement seems intuitive.
other to
Up to increase, down to attenuate. Slide to one side or the
balance channels. Pushbutton selectors permit instant comparison,
switching from one source (top bank) or mode (lower bank) to another
without passing through intermediate positions. Pushed button lights
most
up. Cortrols are so arranged that those most frequently used are
.accessible. Human engineering. Front -panel inputs permit sampling
without disand comparing components connection of portable units
behind a
are
jacks
Front
connections.
chassis
-earpermanent
rupting
Circle 112 on Reader Service Card
AUDIO
SEPTEMBER, 1964
flip -down door which also conceals occasionally used facilities such
as a headphone jack, fuse, filters, system gain, level and balancing
controls. The Graphic Controller includes al ,000 cycle test tone generator to be used for speaker balancing, placement and orientation. An
Aural Null Stereo Balancer accessory provides a very precise means
for balancing speakers, and also the two signals from your stereo
pickup. Performance- wise-in terms of response, distortion, hum -the
JBL solid state Graphic Controller is the finest instrument of its kind
you can buy. As has been said of other JBL products, "It's the result
of doing everything right." In fact the Graphic Controller is so right
in every respect, so well built, so well engineered that yours might
very well become a family heirloom. There's much more to be said
about the SG520. You'll find a complete description in Bulletin SL801 -2.
Write for your free copy and the name of the Authorized JBL Audio
Specialist in your community.
The Graphic Controller is designed, engineered and manufactured by:
JJAMIES B.
LANSING SOUND, I'VC., LOS ANGELES 39, CALIFORNIA
13
amour
MUSIC
Harold Lawrence
"Assisted Resonance "
-A
Revolution In Acoustical Design
Around 330 B. C. Aristoxenus of
Tarantum, a pupil of Aristotle and a
musical theorist, developed a new system
of sound reinforcement for amphitheatres which involved the use of tuned
vases built into the walls. Two thousand
years later, a group of English acousticians, frustrated in their attempts to
cure the sonic ills of London's Royal
Festival Hall, remembered this ancient
Greek acoustical remedy. Adding a dash
of electronics to the original brew, they
called theirs "assisted resonance." If successful, this blending of electronic amplification and resonators could have a profound effect on the future of concert hall
acoustics.
The news about Royal Festival Hall's
"assisted resonance" broke this spring
when the hall's General Manager, T. E.
Bean, revealed that experiments had been
conducted there during rehearsals and
concerts on thirty separate occasions.
Apart from a few technicians and selected guests, the public had been kept
in the dark about the work of the acousticians. Reaction to the experiments
ranged from vague uneasiness to unqualified approval: conductor Sir John
Barbirolli found the hall "warmer," some
orchestral players found they were
"getting more response" from 'the auditorium, and critic Harold Schonberg was
conscious of a "smoothness, richness and
instrumental fusion that definitely puts
the Festival Hall into a superior class."
Others feared the consequences of the
introduction of electronics in the concert
hall.
Bean himself was appalled at the idea
of assisted resonance when it was first
suggested to the management of Royal
Festival Hall. "It seemed to us to imply
practices which we felt certain would be
anathema to the performing musicians
and to the discriminating listener alike
. It conjured up the [picture] of a
`sound engineer' crouching anonymously
back-stage over some high -fidelity control panel, monkeying with the balance,
adding brightness to whiteness, and impudently `improving' on the amateur efforts of Klemperer or Menuhin." But
after the acousticians of the Building
Research Station had cornered him and
outlined their proposals in greater detail,
14
Bean finally gave the project his cautious
endorsement. During the past two years,
his mood changed from skepticism to
guarded optimism.
I set out to visit Bean on a rare sunny
day in London early this summer. Dodging cranes, bulldozers and construction
gangs at work on the new halls emerging
alongside the Royal Festival Hall, I
reached the building in which Bean's
office was located. A workman directed
me down a long corridor to the "last
door on the right." (The sign painters
had not yet labelled the doors.) I entered
a modest -sized office overlooking the
Thames. Soon a gray- haired, bespectacled
man walked briskly into the room, shuf-
Fig. 1. Royal Festival Hall gets a face -
lifting, July, 1964.
fled some papers on his desk, looked up
and saw me standing near the window.
"Hullo
What -er." I introduced myself and his puzzled expression instantly
cleared : "Oh yes, I was expecting you.
But how did you get in here ' This is my
inner sanctum ; the reception room is
down the hall . . Was it the elevator
operator Oh well, we all get a bit confused at times with this construction
going on."
Bean, who has been General Manager
of the Royal Festival Hall for the last
dozen years, feels that the acousticians
have at last taken a significant step
toward improving the sound of this controversial hall. "From the day the Festival Hall opened in 1951 until the summer of 1962 we have been almost continuously investigating the possibility of
increasing its warmth and resonance
without sacrificing those positive virtues
which have given the Hall its distinctive
character; that is, its clarity, its comparative uniformity of acoustics and its
freedom from echo.
"I mention the summer of 1962 because this marked an important landmark in these investigations. By that
...
.
°d
time we had become finally convinced that
no effective lengthening of the hall's reverberation period could be looked for
from any further treatment of its absorbent or reflecting surfaces. Or to put
it another way, we were satisfied that any
increase in reverberation which might
result from such modifications would be
so negligible as to be imperceptible to
the human ear."
Rather than reduce the size of the
audience, rip out the ceiling, or alter the
shape of the building, the acoustical advisers decided to turn to electronics for
help. However, they rejected traditional
forms of sound reinforcement involving
microphone pickups of the program
source and amplification through loudspeaker systems. "Such a technique is
hound to introduce noticeable distortion
or coloration," stated William Allen,
Hope Bagenal's successor at the Festival
Hall. "It is virtually a re- broadcast, and,
because it is usually controlled by an
engineer, a variable human factor is also
added, as in radio and recording, where
of course it is necessary and great skill is
brought to bear."
Bean stressed that the new system developed by Allen, Bagenal (original
acoustical adviser to the Royal Festival
Hall) and Peter Parkin "aims at restoring the acoustical energy where it is unavoidably absorbed by the surfaces of
the hall and by the audience, not at the
source, which would involve an inevitable
falsification of tone, but in the body of
the auditorium where the acoustical energy begins to disappear."
The "assisted resonance" system includes Helmholtz resonators, amplifiers,
microphones and loudspeakers. The experiments began in June 1962 in a disused factory in Bethnal Green. Nearly
two years later, "sufficient progress had
been made in increasing the reverberation of the lower frequencies by assisted
resonance to warrant the testing of the
results under concert conditions in the
Festival Hall itself," Bean related. 89
resonators were installed in the ceiling of
the Festival Hall, each tuned to a specific frequency between 70 and 300 c.p.s.
According to the hall's acousticians, the
reverberation period has now been
lengthened from 1.4 to 2.1 seconds in
these lower frequencies.
Even before the disclosure of the new
system, musicians had begun to comment on the mysterious changes in the
hall's acoustics. Yehudi Menuhin spoke
to Bean about the "remarkably warm
quality of the strings and winds." Rafael
Kubelik asked Bean : "What have you
been doing with the acoustics'? The sections of my orchestra blend better and
the brass now has a more cohesive sound."
Orchestral musicians seemed to feel that
their ensemble playing had improved because of the acoustics. After the public
(Continued on page 61)
AUDIO
SEPTEMBER, 1964
Studio view of three A -7 speaker systems used for 3- channel 1'\.\1Ú1,h monitoring at United
Recording Studios, Hollywood, where many famous musical stars do their recording.
Capitol Recording Studios in Hollywood employ
more than 70 Altec PLAYBACK, speaker systems for monitoring of their famed recordings.
THE POWER AND THE GLORY OF A
GENUINE
VLANBA_C
At the recent L.A. Hi Fi Show, a lady was
so enchanted by the sound of a stereo pair
of Altec A -7 PLAYBACK, systems that she
closed her eyes to their rugged studioutility cabinetry. She wrote a letter conveying the wonder she felt in hearing, for
the first time, faithful reproduction of live
performance. This is what Mrs. Raymond
O. Zenker of Whittier, California, has to
say about Altec's mighty A -7 "Voice of
the Theatre":
`I have never written `letters to the editor' or that sort of thing, but this time I am
compelled to.
"On April 9th, my husband and I went
to the Hi Fi Show at the Ambassador. Of
the many assorted displays, I was impressed only with two big black boxes in
a small ordinary room. These boxes must
have been magical for the room became
enchanting. To others perhaps they were
ugly, but to me they were the most beautiful things -(no, beings, for they were alive
and warm), I had seen during the evening.
"When my husband and I buy, it will
have to be the A -7's. Nothing else is even
worth consideration. This will make the
wait for music a bit longer, but the waiting
becomes a necessity now for I'm spoiled
and could never be content with anything
else..."
Mrs. Zenker's admiration is understandable. "Voice of the Theatre" speakers are
genuine PLAYBACK, systems considered a
must for leading broadcast and recording
studios, as well as motion picture theatres
(including Cinerama's matchless 6 -channel stereo). In such professional applications, where reputations and income are
at stake, "bookshelf" bass, strident highs
and other aspects of audio distortion cannot be tolerated. That's why VIAYBACI,
speakers by Altec are invariably specified.
You can buy a pair of Altec A -7's for your
home for only $288.00 each. Studio engineers will tell you that this is the finest
AUDIO
i
SPEAKER!
speaker system in existence. And it is .. .
next to the new Altec A7 -500.
NEW... ALTEC A7.500
V'LNNBACIC, SYSTEM
For $27.00 more, the A7 -500 provides a
lower crossover frequency and larger sec toral horn for the smoothest reproduction
of lower mid -range ever achieved. However, whichever you choose -the A-7 or
the A7 -500 -your records, tapes and FM
will sound better than they have ever
sounded before. They are priced right in
their studio cabinets; all it takes is a bit
of do- it-yourself ingenuity for dressing -up
or building -in.
PREFER SUPERLATIVE SOUND WITH
FURNITURE TO MATCH?
If you prefer your sound in finest furniture, full- sized, floor- standing, two -way
A of Universal Recording Corp., Chicago,
uses four Altec A -7's in monitoring 4- channel.
Studio
PLAYBACK,.
Altec 41,1ANBACIC systems are also available in walnut or mahogany cabinets.
Hear Altec PLAYBACK, components at
your nearest Altec Distributor's (see your
Yellow Pages). And be sure to ask for
your courtesy copy of Altec's " PLAYBACK,,
And Speech Input Equipment For Recording And Broadcast Studios" Catalog. Although this booklet was prepared specifically for the recording and broadcast
industry, many of the studio applications
it describes will open your eyes (and ears).
Or, for your free copy, write toVLAYBACIC,
Dept. A-9
a term used in the recording
industry to designate the studio sound repro-
*PLAYBACK,:
ducing equipment relied on by conductors,
831A "Capistrano" incorporates A -7 speaker
components in a magnificent cabinet 30" high,
47" wide. Price: $399.00.
performing artists and recording engineers
to carefully judge by direct comparison the
realism of a recording with the live rendition.
Altec Lansing is synonymous with PIAYBACKC,
because most major professional studios have
used and specified Altec equipment since the
early beginnings of modern recording.
ALTEE
LANSING CORPORATION
ALTEC LANSING
838A
"Carmel" contains the A -7 high frequency
section in combination with two low frequency
837A "Avalon" at
speakers. Price: $337.50
$289.50 is identical except for one I.f. speaker
instead of two. Decorator base (shown) $39.00
extra.
Circle 114 on Reader Service Card
SEPTEMBER, 1964
www.americanradiohistory.com
CORPORATION
L`zrdA
Subsidiary of Ling-Ternco-Vought, Inc.
ANAHEIM, CALIFORNIA
01963 ALT£, LANSING CORPORATION
15
EDITOR'S REVIEW
"ASSISTED RESONANCE ":
SINGLE -FREQUENCY REINFORCEMENT
Tins Ai() \ TH in ABOUT Music, Mr. Lawrence discusses the interesting attempt to improve and control acoustics at Royal Festival Hall in England by
means of a technique they call "assisted resonance."
Last month our guest conductor of AUDIO ETC, Dr.
Beranek, discussed the same topic in a somewhat larger
framework. (By the way did anyone notice that the
two illustrations in that column were reversed-the
Moscow Hall was captioned Royal Festival Hall, and
vice -versa ?) Although some of the details are not yet
clear, we do know that the system contains reinforcement for discrete frequencies rather than broad spectrum reinforcement. Thus, in the range from 70-300
cps, the present reinforcement range at Royal Festival
Hall, there are 89 specific frequencies reinforced. Apparently that means 89 Helmholz resonators, 89 microphones, 89 amplifiers, and 89 speakers. And all this
paraphanalia is in the hall proper rather than in the
stage area. In fact the resonators are "buried" in the
ceiling. This reinforces only the sound which would
normally be reflected ; in other words it increases reverberant energy.
This technique points the way towards a new concept of acoustics that may well revolutionize the entire field. To us the significant point here is the potential acceptance of electro- acoustics as a valid supplement to mechanical acoustics. Once it is understood
that using electro- acoustic reinforcement is no more
"unnatural" than using sculpture, decorated walls,
and other physical objects as acoustic aids in concert
halls, but rather is the modern way of doing similar
things, then we will discover many new electro- acoustic solutions. For instance, we can visualize several
ways to accomplish the same function as the "assisted
resonance" technique, and perhaps more economically.
We can visualize them now that the topic has been
broached, now that the pioneers have opened the frontier.
A SHORT SABBATICAL
Usually, when a sabbatical is taken, it lasts for at
least a year. That 's custom, and probably the derivation of the name one year off in seven. But nobody
can accuse Ed Canby of doing things in the customary
manner. Thus, when he felt the need for his sabbatical,
earlier this year, we were quite resigned to expect the
unexpected. We didn't know whether he would be sufficiently sabbated after one, two, three, or three hundred months. It's not that Mr. Canby is not reliable ;
after all he did meet a monthly deadline for 17 years,
but rather that he has an original way of approaching
things. Heaven knows where his originality may have
taken him during this period. Fortunately for us, it
has taken him right back to AUDIO ETC much sooner
than we had dared hope. This month he resumes re;
freshed.
By the way, we must apologize, belatedly, for the
mistaken impression created by one of the guest conductors ; apparently a goodly number of people missed
the name of the guest (Norman Pickering) and assumed that Mr. Canby had suffered a heart attack,
rather than Mr. Pickering. Not a pleasant occurrence
16
in any case, but rather disconcerting to have friends
call and offer condolences when you are as healthy as
Ed Canby is. We do apologize to those who assumed
the worst, but after all, Mr. Pickering's name did
head the column.
QUALITY CONTROL
Some months back we asked for your experiences
with manufactured products insofar as quality control was concerned. Many readers wrote and detailed
problems they had encountered with one manufacturer
or another, but we were happy to note that there was
no consistent pattern indicating that a particular
manufacturer was falling down on the job.
The incidents that many readers reported must have
been quite distressing, and certainly we are unhappy
when we learn that a high fidelity manufacturer is not
perfect, but after all who is ?
We do thank all readers who took time out to let us
know about their difficulties. Further, where possible,
we have attempted to help in specific cases. Please feel
free to write us if quality control seems to be a problem to you. We will try to help, of course, but more
important we will keep a file to determine if a pattern
starts to emerge some time in the future.
BLACK AND WHITE REVISITED
It seems rather soon to have to eat our words, but
that is exactly what we will have to do. Last month we
proclaimed the return of yellow paper stock for the
Commercial Sound Course, this month we un- proclaim
it. Unfortunately, production problems have ruled out
the special paper again. In fact, according to our production people, it is almost impossible to do what we
want to do. We can only say that what you saw in
those first chapters was not yellow paper, but rather
white paper turned yellow with frustration.
In any case, from now on we proclaim nothing, and
perhaps the impossible will be done again.
SHOWS, SHOWS, SHOWS
This year we are all in for a treat, two high fidelity
shows instead of one this fall. The first one takes place
in San Francisco this month. The dates of this show
are September 10-13, and the place is the San Francisco Hilton.
In October we have the New York High Fidelity
Music Show, and it takes place from October 1-4 at
the New York Trade Show Building. Isn't this a good
opportunity for out -of- towners to visit the World's
Fair.
Also in October we have the Audio Engineering
Society Convention which takes place from October 12
through 16 at the Barbizon -Plaza Hotel.
CORRECTIONS
In spite of the fact that the August Product Preview
was the largest and most comprehensive to date, the
number of errors seems to have been exceedingly small.
Most of the errors were cross -reference omissions from
the list of manufacturers, and only a few were mistakes in the product listings themselves. On page 65 we
list the corrections we are aware of.
AUDIO
SEPTEMBER, 1964
look what's happened to the
FOUR MICRO - MAGNETIC* 15° PICKUPS!
Whether you own a record changer, automatic turntable, or a professional type manual
turntable Pickering has engineered the RIGHT V-15 pickup for you. If it's RECORD
CHANGER application, where high output and heavier tracking forces are required try
the v -15
AC -1 Most of you, no doubt are tracking lighter on the late model AUTOMATIC TURNTABLES and will use the v -15
Or if a professional type MANUAL
AT-1
AM -1 And if
TURNTABLE is your choice you'll need the even more compliant
it's unexcelled tracking ability you're seeking, you will demand the ELLIPTICAL STYLUS
PICKUP V -15 AME -1 All four of these pickups are radically different from any other
cartridge. You can see the difference. You can hear the difference. Pick up a V -15. Note
its light weight -only 5 grams. Perfect for low mass tone arm systems. Now, see how
Pickering's exclusive "Floating Stylus" and patented replaceable V-Guard assembly protects your record and diamond as it plays.
j
trade
M
rk
01
Pickering and Co., Inc.
FOR THOSE WHO CAN HEAR THE DIFFERENCE
THE WORLD'S
LARGEST AND
MOST
ícICKERiNG & CO., INC. PLAINVIEW, N.Y.
EXPERIENCED
MANUFACTURER OF
Pickering
MAGNETIC
PICKUPS
Circle 115 en Reader Service Card
AUDIO
SEPTEMBER, 1964
17
Which one of these
100
104
tuner dials lets
98,100,10',
you pre -tune with
professionally - calibrated
accuracy
p
18_IIO_IO2_
98
92
w
b
,t
no
,02_"
ht.
;00
102
104
KR
Only Sherwood precisely graduates its FM tuning dial every 200 kilocycles
minimum spacing between FM station channels. If, for example, the FM
broadcast of your choice is being transmitted at 97.3mc., you can visually
pre -tune the Sherwood tuner dial to receive it with professionally -calibrated
accuracy. Final zeroing -in of the FM station's carrier is merely a matter
of referring to Sherwood's D'Arsonval Zero meter.
Sherwood's new S-ß0001Y FM stereo tuner/
amplifier, $329.50.
Genuine Walnut cabinet optional at $29.50.
-the
Precision tuning is but one of many superlative engineering reasons
for buying Sherwood's new 5 -8000W FM stereo tuner/amplifier. Others
include
80 -watts of stereo music power
1.8µv. IHF sensitivity
FREE-$1.00 value Information Kit
at your Sherwood Dealer.
2.4db. FM capture effect
only 1/3% distortion at 100%
modulation
new "powered" center channel for a
Take this coupon to your Sherwood dealer and receive:
mono speaker -ideal for extension speakers
Time -Saver Shopping Guide-detailed comparative specifications
on components offered by major manufacturers.
stereo headphone jack and separate
64 -page book, An Introduction to Hi-Fi & Stereo published by the
speaker disabling switch.
Institute of High Fidelity.
FM & FM Stereo Station Finder -listing current and proposed
stations
Installation portfolio -a pictorial review of how many different
component systems have been installed.
Descriptive literature on Sherwood components.
If you prefer, send 25c in coin direct to Sherwood, together with
your name and address. Your package will be sent by return mail.
I
Name
Street
City
State
High Fidelity
Zip Code
I
Sherwood Electronic Laboratories, Inc., Dept. A -9
4300 North California Avenue, Chicago, Illinois 60618
STEREO RECEIVERS
TUNERS
AMPLIFIERS
STEREO INDICATOR LIGHTS
SPEAKER SYSTEMS
Circle 116 on Reader Service Card
18
AUDIO
SEPTEMBER, 1964
Automatic Speaker Connector
RONALD L. IVES
suitable use of relay switching, powered from convenient local sources, any one of several
audio devices can be automatically connected to the desired speaker or group of speakers,
with correct phasing. If a second audio device is turned on while the first is operating, it
will warm up, but will not actuate the speaker system until the first has been turned off.
By
US, even as you and I, have
collected several receivers and amplifiers, and use more than one of
them fairly regularly. Most of us, also,
have not yet gotten around to purchasing an independent speaker system for
each "distortion generator." In consequence, change from one amplifier to
another usually involves a wild scramble
of disconnecting speakers from one,
transferring connections to the other,
then looking hurriedly for the misconnection, and finally worrying about the
phasing.
All of this trouble can be eliminated
by use of some sort of speaker switching
device. If the speaker transfer system
can be truly automatic in operation, so
that turning on any given amplifier automatically connects the requisite speakers to it, in the desired phase, so much
the better.
MOST OF
RELAY
BASIC CIRCUIT
This can be done rather simply by use
of relays, which, when properly powered
and connected, are most dependable
switching devices. In addition, relay
switching can take place where it is
needed, eliminating long cables of high power leads to some central panel. The
only problems facing most audio fans
are where to get the power for the relays, and how to prevent trouble if someone turns on more than one amplifier at
a time. Happily, these problems can be
solved easily and inexpensively by a
variety of methods.
BLEEDER
RESISTOR
RELA
(A)
BLEEDER
RESISTOR
Cathode Power
In most high power amplifiers, quite a
few volts, at fairly high currents, are
dissipated as heat in the cathode circuit
of the final audio stage. Many push -pull
Class AB, amplifiers have a cathode bias
exceeding 15 volts, at currents of 80 or
more milliamperes, so that the cathode
resistance is of the order of 180 ohms.
Power dissipation here is about 1.2 watts,
so adequate power is available to operate
any one of a number of 12 -volt 1 -watt
d.c. relays. If current in the circuit is
too much for the relay, a shunt resistance
across it will carry the excess current,
and a series resistor will drop any excess
voltage. Generalized circuit for connecting a "free rider" relay in a power stage
cathode circuit is shown in Fig. 1. Do not
omit the shunt capacitor, or you will
note some new waveforms in the output,
for ordinary relays are inductive devices.
ó
AUXILIARY
RESISTOR
( B)
BLEEDER
RESISTOR
EZ<ER
(C)
Fig. 2. Bleeder operation of relay.
Bleeder Power
FOR EXCESS
ó
z
VOLTAGE
000
RELAY
WORKING CURCUIT
Fig. 1. Circuit of
"free rider" cathode
relay.
AUDIO
SEPTEMBER, 1964
Quite obviously, a relay of proper current rating can be operated in series
with the bleeder resistor of the power
supply, as in Fig. 2A. This arrangement
is not recommended, for opening of the
relay coil, or disconnecting the lead to
the low side, as this will leave the relay
and the "high" lead at a very high potential indeed.
This hazard can be reduced greatly by
shunting the relay with a resistor, as-
suming that adequate current is available, as in Fig. 2B. Now that fairly high
voltage zener diodes are available, a
bleeder connected relay can be made
reasonably safe without requiring extra
current by shunting it with a zener diode
whose voltage rating is somewhat higher
than that of the relay. A circuit for this
is shown in Fig. 2C. Plate type relays,
requiring from two to 15 milliamperes
are ideal for this purpose. When bleeder
currents are quite high, low or medium
19
Separate Supply
SILICON BRIDGE
.
Ly
o2
6.3v.a.c.
tit
k
6
v.d.c.
RELAY
25u COIL
t
2000 Pf FOR EACH 0.3
AMPS DRAIN 10v RATING
Fig. 3. Filament rectifier circuit.
power industrial d.c. relays (such as the
Potter and Brumfield MR series) can be
used in place of the more fragile and
more costly "plate" relays.
Filament Power
For many switching operations, which
require that a device be "ON" when the
amplifier is on, and "OFF" when the
same instrument is off, a relay shunted
across the filament supply performs the
requisite switching function admirably.
Almost any 6- or 12 -volt a.c. relay, of
reasonably good make, with adequate
contacts, will function well here. Rated
voltage of the relay should be equal to
the filament circuit to which it is connected.
When we are dealing only with high level audio circuits, such as speaker lines,
a.c. relays are entirely satisfactory, and
connections by means of twisted pair (of
adequate current capacity) are entirely
workable. Connections consisting of a
long single wire and ground should be
avoided, particularly when one side of
the speaker circuit is also a ground, to
prevent the voltage drop in the ground
return from being injected into the
speaker circuit.
Where high level and low -level audio
circuits are in close proximity, control
lines carrying a.c. should be shielded, as
well as being physically separated from
low -level circuits insofar as possible, to
prevent pickup at 60 cycles, various multiples thereof, and of miscellaneous line
transients.
made to equal the a.c. input voltage
(rms) without the use of costly or bulky
adjuncts.
A preferred circuit for rectifying filament voltage is shown in Fig. 3. Constants here shown are for 6.3 volts a.c.
input. If a higher input voltage is used,
simply increase the voltage ratings of
the components by the same factor. A
full -wave bridge rectifier is used here,
not only because of its efficiency, but
also because its output has a minimum
ripple (120 cycles), and hence requires
a much smaller capacitor than a simpler
half -wave rectifier, all other things being the same. The 0.02 µf capacitors in
this circuit are harsh filters, well worth
the slight extra cost and labor of installing them.
Where available a.c. voltage is quite
low, problems arise in getting enough
voltage output for use with easily-available relays. One solution to this problem
-rectification and filtering to produce a
-
low- voltage at a relatively high current,
which is then applied to an a.c. relay
has already been outline in AUDIO
(Jan. 1964, pp. 36-37). A more elegant
method, using a voltage -doubling rectifier and a standard relay, is shown in
Fig. 4. This circuit is particularly useful
when one side of each line is, and must
remain, grounded.
Where the filament circuit is considerably above ground, the control circuit
can be d.c. isolated from the filament
circuit by use of a small isolation transformer, such as a Stancor type P -8191
(6.3 v. to 6.3 v., 1.2 amperes, 5000 volt
rms insulation).
If the control current needs are greater than can be safely or conveniently
provided by either "free rider" circuits
or by the filament circuit, a separate
supply must be used. This should be
transformer isolated from the a.c. line
for safety reasons; but can have any
convenient voltage, such as nominal 6,
12, or 24, to match available relays. The
primary of the control supply transformer is commonly shunted across the
primary of the power supply transformer, so that switching the main device
also switches the control supply. For
many applications, a 12 -volt (nominal)
control circuit supply is best, as it permits use of 12 -volt relays plus series
transistors for added control, with an
ample margin of safety.
The circuit of a control supply, which
is quite conventional, is shown in Fig. 5
Note its resemblance to Fig. 3, and to
almost any standard bridge rectifier circuit. Because of its conventionality, this
circuit can be adapted for other voltages
and currents by logical and straightforward changes in constants.
Interlocks
When several controlling devices are
used, some provision must be made to
prevent interference of functions. If
this is not done, two or more controlling
devices may inadvertently be switched
on at the same time, with unhappy or
devastating results. Signal output of a
speaker fed from two receivers simultaneously is seldom pleasing to the listener, and interconnection of two amplifiers, through the output circuit, may
not be beneficial to either of them, particularly when certain forms of feedback
are used.
To eliminate this annoyance or difficulty, a simple interlock, so designed
that when the speaker is connected to
one circuit, no other circuit can be connected to it, is desirable. Simplest form
of this interlock, here shown for two signal sources, is shown in Fig. 6. With this
circuit, when one relay is actuated, the
other relay circuit is opened, so that if
the second control line is energized, the
second speaker line cannot be connected
to the speaker until the first control line
Rectified Filament Power
Where hum pickup from control lines
or relay coils is, or might be, a problem,
control by means of rectified filament
power is preferable to use of raw a.c.
With highly dependable silicon rectifiers
available at relatively low prices, and
high- capacitance compact electrolytics
"over the counter" items, rectification
and filtering of low voltage a.c., such as
from the filament circuit of an ordinary
amplifier, is no longer a serious problem. In addition, because of the efficiency
of modern silicon diodes, d.c. voltage output of a rectifier -filter system can be
20
2000
.02
NF
\
F-6
Ly
10 v
1.
-6
c,1.
RELAY
25. COIL
IT
Fig. 4. Voltage- increasing rectifier circuit.
AUDIO
SEPTEMBER, 1964
MAIN
POWER
TRANSFORMER
41,
110
v. a. c.
60 cps
SUPPLY
SILICON BRIDGE
13.5 v.
APPROX.
1
12-VOLT
FILAMENT
TRANSFORMER
6000 pf
PER
AMPERE
OF LOAD
Fig. 5. Control supply circuit.
is de- energized. This same principle can
be expanded to a system of N relays, con-
tact requirements per relay then being
those for the speaker connections plus
N -1 SPST NC contacts per relay for interlock. Double pole contacts are shown
here for the speaker connections to facilitate phasing. Where phasing is unimportant, and one side of each amplifier
output is grounded, single pole contacts
are adequate.
With this arrangement, either a.c. or
d.c. relays may be used, the control circuits are electrically independent except
for the interlock, and there is no compatibility requirement between them
all that is necessary is that they be capable of operating the relays connected to
-
them.
Although this method of interlock is
theoretically capable of almost infinite
extension, its practical limit is three controls with double -pole switching, and
four controls with single -pole. Larger
systems run into rather extensive cabling
and contact maintenance problems. Systems involving more than three or four
controls are best interlocked by use of
transistor-gated relays and diode matrices, a technique which has been detailed elsewhere.1
=Z OF SPEAKER
W =1.5 W OF SPEAKER
R
Safety Measures
Too many audio systems are wired
according to the general principle that
anything that works once goes, however
some care in planning and constructing
the control system will eliminate not
only a lot of diddling to find out what
quit this time, but will also keep the
building inspector happy and your fire
insurance valid.
All control supplies should be fused
close to the source, so that a short circuit
in the output will burn out the fuse, and
not the rectifier or power transformer.
1 Ives, R. L., "Simplifying Control Interlocks," NRI Journal, in press.
SPEAKER
OUTPUT
OUTPUT 2
1
CONTROL
CONTROL
1
EITHER
A.C.
OR
D.C. RELAYS MAY
BE
Fig. 6. Simple interlock circuit.
AUDIO
SEPTEMBER, 1964
Replacement fuses are very much cheaper than replacement rectifiers or transformers.
Control lines, even though they carry
relatively small currents, should be made
of good grade wire, adequately insulated,
and physically strong enough to handle
the mechanical stresses to which most
cords are subject during their service
life. Despite their convenience and low
price, some of the dual "zip cords" now
on the market should not be used, as they
are apparently insulated with used chicle,
and they tend to short out after a few
months of use.
Wherever possible, control lines should
be connected by use of distinctive plugs,
unlike those used for any other connection in the installation, so that a wrong
connection cannot be made. Use of female connectors for "hot" (source)
leads, and of male connectors for cold
(load) leads, is a recommended practice,
even when voltages concerned are harmlessly low.
When interlocks are used, some means
USED
2
IEB4
AUDIO LINE
I
1
INTERLOCKS
OTIïR
INPUTS
o
CONTROL LINE
Fig. 7. Protective resistive loads.
must be provided so that all amplifiers
operate with a load. No-load operation
of some amplifiers can result in oscillation, with resultant damage to the output transformer, and possibly to other
components.
This problem can be solved most simply by the use of suitable load resistors,
as shown in Fig. 7. With this arrangement any speaker line that is not connected to a speaker is connected to an
equivalent load resistor. In consequence,
any amplifier that is turned on is automatically loaded.
Although careful labelling of all output plugs and cords may seem unnecessary, this practice saves a lot of errors
and blunders during the life of the
equipment.
The cost of an automatic audio switching system is relatively small, and maintenance needs are also small, if good
components are used initially, and high
grade workmanship is used throughout.
Æ
21
Transient Generators
For Audio Testing
JOHN L. GRAUER
Circuits are given for simple transient generators which can be inexpensively built
with standard parts, to evaluate impulse response of audio equipment, using
a sinusoidal tone -burst, a non -sinusoidal tone -burst, and step- function signals.
APRINCIPAL CONCERN
of designers has
been the evaluation of steady-
state frequency response of audio
equipment. This has proven rather easy
to do, as there is much test equipment
available to verify results. One can
readily sweep the circuit under test with
a signal, and measure the magnitude deviation at the output. A continuous signal facilitates measurements with simple
equipment, because the signal can be
kept on long enough for the operator to
obtain readings. The wave is normally a
sine wave.
Another important test is under
transient signal, to ascertain that the
design will do justice to changing waveforms and impulses, which occur in all
music. The square wave test is often
used, on the assumption that equipment
able to handle fast rising waves with a
d.c. component will sound better.
The extreme difficulties with this notion have been brilliantly elucidated by
Crowhurst, for both high -frequency and
low- frequency cases. Part of these come
from trying to evaluate transient performance with a continuous signal which
tends to set up a steady -state condition
in the equipment under test.
Briggs has shown that for speakers
there seems to be no relationship between the bandwidth and the transient
response, and has designed a simple test
circuit for evaluating speaker transient
response. As this method utilizes a d.c.
*
8 Garden St., Great Neck, N. Y.
SCOPE
AUDIO
TRANSIENT
GENERATOR
OSCILLATOR
EQUIPMENT
UNDER TEST
... -
TIME
22
0
'71--Ir~
Fig. 2. Equipment setup for transient response tests by transfer characteristic.
step function signal, which is certainly
In feedback amplifiers peaks and resa true impulse or transient, the results onances occur at very low frequencies, on
obtained would seem to bear a closer the order of J. or 2 cps, and can occur
correlation to non -steady-state perform- even when steady-state response eviance.
dence is swamped by output transformer
The difficulty here is that the signal rolloff. The seriousness of this, on prolasts only a fraction of a second, and ex- gram, has been pointed out by Crow pensive photographic equipment, along hurst. Obtaining such resonance data is
with very low sweep rates, seems neces- doubly difficult both because of swampsary to compare results. In addition, no ing, and because of limited test equipnumbers can be readily assigned to the ment range : most oscillators do not go
amount of deviation found, as, for ex- below 20 cps, and most voltmeters and
ample, a 5 per cent transient distortion. a.c.- coupled display devices become inThe scope, however, does display the creasingly inaccurate below 20 cps.
deviation accurately, and with random
The problem, then, is twofold. First,
repetition of a standard signal, and a what is a proper signal to expose such
little care, it is possible to get a good effects, and, second, how can a test be
idea of the seriousness of the defect.
conducted so that expensive equipment
Very sophisticated delayed response is not needed to evaluate effects taking
curves have been done, but these require place in a short time. The test must aselaborate equipment, a certain amount sure that under typically musical condiof time to plot the results, and skill in tions, where the material (signal) is
interpretation.
changing continually and virtually at
random, the very low frequency region
will be non -resonant and well- damped.
5
The proper way to do this is to feed
in a signal which will excite such a res4
onance, and evaluate the distortion proFig. 1. Ideal transó
duced. This must be accurately done at
fer characteristic the moment without extensive
photopatterns using a
z
switched sinusoi- graphic means-so that the circuit can
be conveniently changed and re- evaludal waveform.
ated until the required performance is
obtained.
Experiments revealed that transient
distortion of this type can be observed
by switching a steady wave on and off, or
3
45°
LOAD
-
AUDIO
SEPTEMBER, 1964
SHORT LEAD BROUGHT OUT
TO SCOPE HORIZONTAL
27k
D
N.
Z7
o
iSPST -NC
PARTS LIST
1
MINIBOX 4x 21/4x 21/4
PUSHBUTTON SWITCH,
SPST NORMALLY CLOSED,
SWITCHCRAFT FF -I002
1
1
12k
1
/2w,
10% RESISTOR
Fig. 3. A.C.
1
IRk
1
/2w,
10% RESISTOR
10% RESISTOR
127k /2w,
1
1
I
2
10k POT,
I
/2w
KNOB FOR POT
AUDIO JACKS
transient generator.
on and partly off, and viewing the deviation produced as a transfer characteristic non -linearity on a d.c. scope.
The tests require a d.c. scope with
identical amplifiers, and thus low phase
difference between channels, such as the
Heath I0 -10 ($80), a sine generator
(Knight audio generator), simple auxiliary devices described herein, and, of
course, the equipment under test.
Evaluation by transfer characteristic
works well because any very low frequency transient effects appear on the
scope as a slow vertical modulation
(bounce) of the trace, which dies out in
a short period of time (about 1/2 second).
In an ideal case, there is no vertical
oscillatory motion, and the recovery
time from a peak signal of any duration
lator is fed through a transient generator, and the unit under test, which is
terminated in its proper load. The vertical scope input feeds from the load,
while the horizontal scope input feeds
from the output of the transient generator. What is seen on the scope is a disunique
play of input versus output
dynamic "dual trace" -which shows both
steady -state and transient distortion
-a
components with accuracy and perspective. This occurs because amplifier deviations are present only in the vertical
channel, while the horizontal channel always follows the input signal.
This gives the total picture of instantaneous difference in signals at every
moment. The effect of reactive loading
can also be seen. In addition, valid tests
can be done with signals of other than
sinusoidal shape.
The transient generator used in the
setup of Fig. 2 is shown in Fig. 3, and
consists of a resistive network and pushbutton switch, which turns the wave
passing through on and "off," when the
operator pushes the button. The waveform produced is shown in Fig. 4. The
audio oscillator output control determines the larger amplitude level. The
lower level can be adjusted from 0 (off)
to about 2/8 of the larger amplitude, by
setting the pot. A 4- or 5 -to-1 ratio gives
good readings, though this can be
changed as required.
is zero.
The ideal pattern can be seen by feeding the input transient to both scope
inputs (vertical and horizontal), where
the trace should appear as a straight
line (at any frequency), always 45 -deg.
from the horizontal plane, with the
length in direct proportion to the signal
amplitude. The pattern is shown in Fig.
1, for a sine wave of 5 to 1 change in
amplitude.
As the signal amplitude is switched up
and down, the trace jumps between the
small pattern and the large pattern.
Because the scope sweep generator is
disabled for this test, the trace actually
remains centered on the screen, without
horizontal movement, as shown in Fig. 1.
The line therefore sits still, and appears
to lengthen and shorten instantly with
switching.
The basic setup for taking transfer
characteristic traces is shown in Fig. 2.
The signal generated by an audio oscil-
Fig. 4. Output wave of generator.
AUDIO
SEPTEMBER, 1964
Fig.
5.
Transient transfer characteristic
pattern.
The design of the a.c. generator derives
from a "straight" resistive voltage divider circuit, where the output signal is
equal to Ern times (R1) /(R, +R2). Etn
is the a.c. voltage applied to the high
side of the divider ( top of R,), with the
output voltage being taken from the
junction point of R, and R,. R, returns
to ground. In this design, R, is 27k,
while R, is split into a 10k pot and an
18k fixed resistor. A normally -closed
switch-which should have no contact
bounce, to give cleanest make and break
-shorts out most or all of the bottom
leg (R,), which reduces the value of this
resistor to anything from 10k through 0
ohms. Any Etin signal applied is then attenuated by a factor continuously variable from about Ein /4 through infinity.
This gives complete control of the lower
amplitude level.
When the switch is touched (opened),
the attenuation is reduced by "unshort-
(A)
0 LEVEL
(B)
Fig. 6. (A) Asymmetrical generator; (B)
waveform of asymmetrical generator.
ing"
R making the signal rise instantly
to
EtnxR, /(R, +RB) _
10k +18k
Ean
x 10k + 18k + 27k =115
Ein.
When the switch is released (closed),
the amplitude jumps back to the lower
level.
An important feature in the design is
the 12k resistor across the input, which
serves to bleed a signal current to ground,
and thereby stabilize the input voltage
applied to the resistive network from
the oscillator. Also, the switch used, most
conveniently a pushbutton type, must
have very low contact bounce, otherwise
it will tend to cause an imperfect and
confusing transfer characteristic pattern during the switching interval. An
inexpensive switch, Switchcraft model
FF -1002, serves admirably, having a
contact bounce which is virtually undetectable. It consistently outperformed
switches of other type and construction.
By using the switch to effectively short
out part of the signal, rather than to,
say, alternate between two signals of
different level, a good clean switching
pattern is assured, because of only two
modes of operation (up and down). With
an alternating design, a third mode would
be present -during the time interval between the switching break and make.
Even a very fast switch would tend to
blemish the pattern purity in this in(Continued on page 59)
J
i--..-
LE
,CL
Fig. 7. Waveform of d.c. generator.
23
A Note on Curve Plotting
VIRGINIA RETTINGER
The use of the time constant of a particular circuit as
a means of expressing the shape of a curve is becoming
more common. Here's how to use this technique.
and
audio engineering often employs the
concept of time constant (of a particular circuit) for describing the response curve of an amplifier. Some
readers may not be familiar with this
concept, or else, may not wish to take
out the time in making a whole series of
calculations (depending on the number
of circuits involved in the description of
the curve). It is the purpose of the following to clarify this concept of time
constant and to provide a set of curves
which quickly provide the required information.
As an example consider the following
text, taken from the EIA Standard
RS -288 "Magnetic Playback Characteristic at 71/2 ips:"
THE LITERATURE OF ELECTRONICS
2.2.1 IN GENERAL, a curve
that
falls with increase of frequency at
the rate of 6 db per octave, but
-
modified
2.2.2. AT LOW FREQUENCIES,
be a curve that falls with decrease
in frequency in conformity with the
admittance of a series combination
of a capacitance and a resistance
having a time constant of 3180
microseconds, and further modi-
fied-
2.2.3. AT HIGH FREQUENCIES,
by a curve that rises with increase
in frequency in conformity with the
admittance of a parallel combination of a capacitance and a resistance having a time constant of 50
microseconds
2.2.4 THE COMPOSITE CURVE
is shown in Figure 6 of the N.A.B.
Recording and Reproducing Standards Supplement #2 dated June
-
1953.
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There is obviously no problem connected with the first part of the above
text which calls for a curve that falls
with increase of frequency at the rate
of 6 -db -per-octave. The second paragraph, however, may present a problem to some, particularly when no guiding curve is supplied with the text, as
(Continued on page 63)
1111/I
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4.1.,,
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11,21/I10.IAI1111P2111
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sON073SONDIW NI INVI$NOD 3W11=1
Fig. 1. Curve showing the time constant of various circuits at a particular frequency.
AUDIO
SEPTEMBER, 1964
Over two years ago, word leaked out (as it will) that
Shure, one of the world's most respected manufacturers of high fidelity components, had embarked on an
epochal project: the creation of a perfectionist's compact stereo system. A high fidelity system that conjoined
optimum sound and minimal size.
A formidable and dedicated group of development and
design engineers was given carte blanche.
Independent high fidelity authorities were flown in for
repeated consultations. Their
recommendations and comments provided a demanding
framework for Shure engineers.
The M100 embodies significant and unique engineering considerations, such as a solid -state pre -amplifier/
amplifier developed and produced by Shure with more
than ample power to drive its two total- range, ultra compact multi speaker systems, also designed by Shure.
And, it features the renowned Shure Bi- Radial Elliptical
Stylus in the famed V -15 Stereo Dynetic 15° tracking
cartridge. Naturally, it cannot scratch records. Dual's finest precision Model 1009 automatic turntable is standard.
The M100 can be used with
AM, FM, Multiplex tuners, or
be used as a public address
system. Ideally suited for every
PERFECTIOHISM
Prototypes were modified and improved ...
and improved again ... and again.
The monies and skills appropriated to the
project were sizable
by ANY standards.
Perfectionism is not inexpensive,
ever.
-
THE M100 SYSTEM
home -listening requirement,
the M100 is also recommended for use in
schools, hospitals, and other institutions. It is
Underwriters' Laboratories, Inc. listed.
Space is not sufficient here to list all the
M100's pertinent specifications.
INEXP ENS! VE,
The result of this highly disciplined
creativity is Shure's M100 Maximum Performance component high fidelity
system. It is not just good, it is great.
It will re- create your favorite records with a
sound quality that is remarkable in its naturalness and exciting in its impact. It is unlike anything
previously available in compact systems-save perhaps
a highly- inspired custom component rig costing two
(or more) times as much. The M100 costs around $400
to $450 depending on cabinetry or case.
Because of the singular standards for sound and for
size that were set for the M100, few components were
judged to be satisfactory for inclusion in the unit. Consequently, the Shure design staff (that developed the
unique Dynetic cartridge which made true high fidelity stereo a practical reality) designed many of their
own components. In addition, quality is controlled by
the famous Shure Master Quality Control Program.
They are for a system of this size,
singular. We will be happy to send
complete specifications to technically oriented music lovers.
LIMITED QUANTITIES
Because of the detailed craftsmanship, large
amount of hand -labor, and rigid quality control and inspection techniques involved, the
number of M100 systems manufactured will be few.
They will be available only through a select group of the
most experienced high fidelity consultants and dealers.
We cannot promise immediate delivery. For perfectionism cannot be mass produced.
E VER
THE M1 OOL
PORTATIVE SYSTEM
two instrument cases. Recommended for serious listening among
music lovers on the go: armed forces
members, boat owners, college students, school music directors, or anybody given to travel. Or summer cottage owners, of course.
In
THE M100W LIBRARY SYSTEM
Impressive solid walnut cabinetry
designed to complement the decor of
modest or magnificent homes and
apartments.
-- HVI=?E
MAXIMUM PERFORMANCE COMPONENT MUSIC
RE- CREATION SYSTEM
Shure Brothers, Inc., 222 Hartrey Ave., Evanston, Illinois
Circle 118 on Reader Service Card
AUDIO
SEPTEMBER, 1964
25
IITRI:
R
&
D
For The Tape Industry
ROBERT ANGUS
What's new in tape? AUDIO decided to find out by
going to the pioneer research organization in this field.
1939, a junior at Illinois
Institute of Technology was faced
ONE DAY IN
with a problem his cousin was
studying singing, and needed a low -cost
device which would enable him to hear
himself as he practiced. There were disc
recorders on the market-but the cost of
a large number of discs would be high,
and these recorders were both bulky and
inconvenient for an amateur to operate.
So Marvin Camras began experimenting
with a device which could record sounds
on piano wire by magnetizing portions
of wire. Because the same length of
wire could be used to record over and
over again, the wire recorder would answer his cousin's prayers. By the time he
graduated the following year, Camras
had developed a machine which would
record a wide variety of sounds for electronic playback. That wire recorder,
which the student brought along to class
to show his professors, was an early
milestone of an organization which has
become known as the back room of the
magnetic recording industry-the laboratory in which research and development
is done for IITRI's magnetic recorder
licensees in the United States and around
the world.
:
IITRI -The House
of Research
1940 was known as
Armour Research Foundation, had been
founded four years earlier by IIT faculty members to provide coordinated research for industry. Upon his graduation, Camras was urged by his professors
to join ARF and continue his research
into magnetic recording. At the time,
most activity in magnetic recording was
taking place in Germany. The Magnetophon, manufactured by AEG, used a
plastic tape and operated at 30 ips-but
the German Ministry of Propaganda was
taking all the units AEG could produce,
and wrapping them tightly in a blanket
of security. In 1941, Camras' experimental work on wire recorders was put to
good use when the armed services asked
Armour to manufacture recorders for
military use. During the year, he developed a method of a.c. biasing in use on
all high fidelity recorders today, and
Armour applied for a patent on it. The
patent is one of 400 held today by IITRI,
the income from which provides the financing for further research into magnetic recording by Camras and an IITRI
staff.
Other Camras -IITRI patents include
IITRI, which in
Fig.
1.
wire
shown
one of hunThe
recorder
here is
dreds
made
by
Armour Research
Foundation during
World War II for
the U. S. Armed
Forces. At left is
Marvin Camras,
who developed
and patented the
machine in 1939.
(1943)
26
Fig. 2. Camras adjusts film in projector
modified to pick up magnetic sound
stripe. (1956)
manufacturing audio tape which
covers most of the sound tape on the
market today ; one covering the use of
high frequency bias, which produces high
fidelity tape sound; the non -automatic
straight -line feed system used by most
manufacturers today on recorders; a
head assembly which insures complete
one on
erasure of recorded tape, preventing the
intermixture of new and old recording;
the cross -field head, introduced last year,
which yields high fidelity at slow tape
speeds; and a compatible automatic tape
cartridge playing system.
From its somewhat informal beginnings, IITRI has grown to include a staff
of 1752 persons, nearly half of whom are
professional personnel, working on projects totalling an estimated $25 million.
IITRI owns a physical plant worth more
than $25 million, not including a $10million 20 -story research tower due to
open early next year. In addition to its
research on magnetic recording, it has
15 departments covering a wide range of
industrial and governmental research.
The departments are Physics Research,
Geophysics Research, Fluid Dynamics
Research, Astro Sciences Center, Metals
and Ceramics Research, Chemistry Research, Life Sciences, Electronics Research, Computer Sciences, Product
Development Center, Mechanical Engineering, Solid Mechanics Research, Management Research, Extra- Hazardous
Test Facilities and Research Services
and Principal Equipment. Some of the
AUDIO
SEPTEMBER, 1964
BUY THIS FIXED- POSITION MICROPHONE
...GET THIS LAVALIER
FOR ONLY
$5.00
OFFER IN THE INTEREST
OF IMPROVED SPEAKING TECHNIQUES
A SPECIAL
For lecturers, teachers, ministers,
managers, public speaking requires
the freedom and flexibility of a second microphone. The ability to move
around while talking frees the speaker
for writing on a blackboard or handling visuals, makes any speaker more
interesting, more effective. Prove it to
yourself for only $5.00 when you buy
a Shure Microphone for fixed -loca-
This special limited -time offer applies
to the famous Unidyne II and Ill
series and other fine Shure microphones listed below.* Unidyne III is
the only cardioid microphone with
pick -up pattern symmetrical about
axis and uniform al all frequencies.
Outstanding for voice or instruments.
*Models 300, 315, 330, 333, 555W,
55S, 545,
546, 5565, 576, 578, 578S. A Shure
Lavalier for only $5.00 with each, when you
send in your guarantee registration card.
Offer expires December 31, 1964.
545S,
tion use.
Steps to obtain your Lavalier
Microphone:
Purchase any of the microphones listed above
thu your
dis-
tributor or sound installer.
Shure Brothers, Inc., 222 Hartrey Avenue, Evanston, Illinois
Remove guarantee registration card from microphone package.
Specify whether you wish high impedance or low impedance
lavalier microphone in the comment section of guarantee registration card.
Mail to Shure Brothers, Inc. with your check or money order for
$5.00. If sending cash please send by registered mail.
That's all there is to do. Your microphone will be sent to you
post paid. Sorry, no C.O.D.s.
AUDIO
SEPTEMBER, 1964
27
a recorder actually included a cross -field
head on a model in the U. S. market."
The cross -field head is designed to record
high frequencies at slow tape speeds
obtaining at speeds of 17/8 ips and 33/4
ips frequency response which used to be
obtainable only at 71/2 or 15 ips. It does
this by reshaping the magnetic field of
the recording head to make a sharper
recording pattern. In the cross -field design used by Roberts Electronics, for
example, a coil is located on the underside (uncoated side) of the tape, opposite
the record /playback head. In the alternative design, outlined in the 1952 bulletin and due to be introduced later this
year by Concord Electronics, the extra
coil wraps around the record /playback
head and produces a magnetic field from
the same side of the tape as the recorded
signal. By creating a sharper field for
recording, Camras explains, it's possible
to get more wavelengths onto a given
length of tape. Unfortunately, he admits,
so far little has been done to improve
tape transports to reduce wow and flutter. The result is a desirable frequency
response which he calls "somewhat meaningless, because distortion from mechanical causes becomes so much more evi-
-
Fig. 3. Automatic
tape cartridge
changer uses cartridges the size of
large
pill
box
loaded with stan-
recording
dard
tape. Number of
cartridges
which
may be stacked at
once and changed
is
automatically
almost unlimited.
research is done under contract, such as a
$280,000 study of metal fatigue, paid for
by 20 industrial sponsors; and space exploration research supported by the National Aeronautics and Space Administration. In other cases, royalties from
patents which develop as a result of these
and other research projects help to pay
for additional research. IITRI, although
it is a non-profit -making organization,
certainly pays its own way.
A Chief Resident
Camras today is a youthful (though
harried) engineer of 48. His interests,
when AUDIO talked to him recently in his
office at IITRI, include a good quality
home videotape recorder ( "We don't
have it yet, "), a revolutionary development in tape as an instrument for business dictation ( "We're close to that, "),
a cartridge player system which is compatible with reel -to -reel recorders and
can produce top fidelity ( "We've had it
for several years ") and a way of getting
high -fidelity reproduction at slow tape
speeds ( "We've licked a number of electronic problems. Now we're faced with
mechanical ones "). He divides his time
between work and membership in 11 professional associations and societies in all
of which he takes an active part. Somehow, he still has time for his wife and
three children who reside in suburban
Glencoe, Ill.
The history of recording on tape in
America is the story of Marvin Camras'
research since 1940. By 1942, for example, he had designed a wire recorder to
fit Navy specifications. In 1946, while
Ampex was studying a captured German
Magnetophon to learn the secrets of
manufacturing one and J. Herbert Orr
was trying German formulas for iron
oxide and a binder, Camras was experimenting with sound -strip film. The following year, scientists at Minnesota Mining developed their own iron oxide and
magnetic tape, only to find that the process they'd developed was already covered
by a Carnras patent. In 1949, as the first
28
monophonic tape recorders suddenly won
favor with the public, Camras held demonstrations in Chicago of stereo sound on
tape. In 1954, he received the John Scott
award for scientific achievement -the
same honor bestowed upon such notables
as Thomas Edison, Orville Wright and
Madame Curie. The 138 -year-old award,
consisting of $1000 in cash, a copper
medal and a scroll was presented to him
for his discoveries and subsequent improvements in magnetic recording that
helped skyrocket the industry into
one doing an annual business well in excess of $160 million. He received the Illinois Tech alumni distinguished service
award in 1948 and the U. S. Camera
award for contributions to motion picture photography in 1949.
Some steps are long
...
Not infrequently, it's a long step from
Camras' laboratory to the living room.
An excellent example is the cross -field
head, which Armour first outlined to its
licensees in a bulletin issued in 1952.
Notes IITRI vice president Dr. James
Brophy, "Although the design has been
available to any licensee at any time
since then, it wasn't until last year that
dent."
Dr. Brophy feels that with the tapes
available in 1952, results with the cross field head probably wouldn't have been
very exciting. The low -noise tapes introduced for home use this year, however,
have interested IITRI's tape recorder
experts, very much-partly because they
improve the signal -to -noise ratio, which
becomes more of a problem at 17/8 ips
with the cross -field head. "You couldn't
hear well enough before to care," one
tape expert noted upon hearing the
cross -field head. "Now things like signal to -noise and wow and flutter become
that much more important."
The cross -field head is one step in
IITRI's long -range goal to reduce the
"standard" speed of tape from 71/2 ips
(Continued on page 50)
Fig. 4. IITRI automatic tape cartridge changer goes from one tape to the next
a
with
minimum of interruption.
AUDIO
SEPTEMBER, 1964
No other solid state stereo
tuner/amplifier kit has EICO's
$500 -$ó0o quality...
88
90 92 94 96 98 100 102 104 106 108
and looks it. (for only $2292g)
Introducing the new 3566 all transistor F.M. M PX Stereo
Tuner /Amplifier. Designed throughout to the quality level
of the costliest Tuner /Amplifiers on the market.
SUPERIOR TRANSISTOR SOUND: Perfect deep bass fidelity, the clarity
and detail of exactly reproduced transients ... the sweet, airy quality
achieved with extremely low distortion and extended frequency response.
Plus plentiful reserve power for orchestral crescendos (even with inefficient speaker systems) -all against a velvet quiet background: This is the
new transistor sound that is taking over in high fidelity...This is the
sound of the superior new EICO 3566.
UNSURPASSED FM STEREO TUNER PERFORMANCE: Entirely new FM
"Front End" and 4 -Stage IF Strip with wideband ratio detector, developed
only after the practical requirements of optimum FM Stereo performance
were established by experience with earlier transistor designs in the field
...Achieves Minimum Bandwidth Variation with signal level for consistently high quality reception regardless of signal strength .... Handles even
abnormally strong signals without overloading (a strong local signal won't
"blanket" the dial)... Unsurpassed usable sensitivity with only slightly
more signal required for full 40db quieting. Time-switching transistor
multiplex circuitry, incorporating separation and balance adjusts, achieves
outstanding 38db channel separation... completely effective filtering of all
types of interference. Noiseless, purely electronic Automatic Switching
between FM Stereo and FM Mono (controlled by the pilot frequency in
stereo broadcast signal), with defeat. Stereo Indicator Light gives instantly
visible indication of stereo broadcasts... D'Arsonval tuning meter gives
exact center-of-channel tuning indication ...Adjustable -threshold interstation noise muting gives you silence between stations while tuning, and
infallible stereo program indication. Convenient Muting -Off Switch for
weak station reception ...Exactly right AFC pull -in range permits you to
tune in stereo stations accurately with ease. Convenient AFC -Off switch for
tuning in weak stations.
out...
FM "Front End," 4 -stage FM IF strip, and entire multiplex circuit
pre-wired and pre -aligned ...Transistor Sockets eliminate risk of transistor
heat damage...This kit can be recommended to beginners!
CONTROLS: Input Selector, Mode (incorporates FM stereo defeat), Volume,
Balance, Bass, Treble, Loudness Compensation, Muting -off, AFC -off, Power
on-off. INPUTS: Mag. Phono, tape, auxiliary, 300 Sé antenna. OUTPUTS:
left and right speakers, tape, headphones. INDICATORS: Illuminated
tuning dial, tuning meter, stereo program indicator light. FUSES: Line,
Left Speaker, Right Speaker, SIZE (HWD): 5 x 161/2 x 131 inches.
AMPLIFIER/PREAMPLIFIER SPECIFICATIONS: POWER: 66 watts total IHF
music power output. IM DISTORTION: 2% at 30 wpc (watts per channel);
1% at 25 wpc; 0.3% at normal listening level. IHF POWER BANDWIDTH:
20- 20,000 at 25 wpc, 0.5% harmonic distortion. HARMONIC DISTORTION:
0.16% at normal listening level. FREQUENCY RESPONSE: ± 1db 10-60,000
cps. HUM & NOISE: 70db below 10mV on mag. phono; 70db be ow rated
power on other inputs. SENSITIVITY: 3mV on mag. phono, 180mV on other
inputs. SPEAKER CONNECTIONS: 8 -16 ohms.
FM MPX STEREO TUNER SPECIFICATIONS: SENSITIVITY: 2
microvolts for
30db quieting (IHF Standard), 2.7 microvolts for 40db quieting. VHF HARMONIC DISTORTION: 0.5 %. CHANNEL SEPARATION: 38db. FREQUENCY
RESPONSE: ± 1db 20- 15,000 cps. IHF SIGNAL -TO -NOISE RATIO: 60db. IHF
CAPTURE RATIO: 4.5db. IMAGE REJECTION: 50db. IF & SPURIOUS REJECTION: 80db. SCA REJECTION: 40db. 38 KC SUPRESSION: 55 db. 19 KC
SUPRESSION: 45db.
EICO 3566 also available factory wired (includes oiled walnut cabinet)
$349.95 ...optional oiled walnut cabinet for kit $9.95.
Visit the EICO exhibit in the Pavilion of American Interiors at the World's Fair.
UNSURPASSED STEREO AMPLIFIER/PREAMPLIFIER PERFORMANCE: Entirely new amplifier /preamplifier circuitry, designed with the highest performance objectives. Phenomenally low noise, low distortion RIM phono
preamplifiers with maximum overload resistance. Low distortion, variable
inflection feedback tone controls permit boost or cut at the extremes of
the range without affecting mid -range response or the volume level. Isolated from power amplifier by buffer stages to eliminate loading distortion.
Unique, very low distortion drive of power amplifier output stages, plus
36db of overall feedback to reduce distortion to an inaudible level. No output transformers -giving unrestricted bass response and eliminating transient distortions normally occurring due to output transformer characteris-
r
Instrument Co., Inc.
131 -01 39th Avenue, Flushing, N.Y. 11352
Please send 1964 Catalog
F:Itr1
Name
Address
tics.
SIMPLIFIED KIT ASSEMBLY: You wire only non -critical audio and power
supply circuits, mostly on military-style terminal boards for easy check-
1
EICO Electronic
City
L
lone
State
-
--
A-J
Circle 119 on Reader Service Card
AUDIO
SEPTEMBER, 1964
29
www.americanradiohistory.com
3m
COMPANY
THINK YOU HAVE A GREAT SOUND SYSTEV NOW?
.,==
t, r
rì
REVERE -WOLLENSAK M -20 AUTOMATIC
STEREO TAPE DECK The newest idea in music
now for custom installation! This amazing machine threads, plays, rewinds, changes tapes
automatically. Up to 15 hours of uninterrupted
music just by touching a button. Dual record/
playback preamplifiers. Record in stereo or
mono from any sound source, or choose from a
wide assortment of pre- recorded tapes. Keyboard controls ... high speed search lever
automatic and delayed shut -off ... unsurpassed
sound -on tape reproduction. Also available in
playback -only deck version, Model M -30.
SIZE: 141/2" x 141/4" x 7". WEIGHT: 32 pounds.
...
,
.
ff5.-1
,()
ri
-
WOLLENSAK 1981 "SOUND ROOM" STEREO
TAPE DECK Designed for the serious tape
recordist, incorporating two new module -type
recording and playback amplifiers which provide 22 watts output. Superb stereo or mono
recordings can be made from any sound source.
Vertical or horizontal operation ... 2 VU recordconvenient tab controls perform
ing meters
all playback and record functions
sound
dual speed .. automatic tape
with sound
...
...
...
.
lifters ... patented balanced tone control
patented head demagnetizer .
.
complete
professional stereophonic sound advantages.
SIZE: 211/4" x 133/4' x 95/16 ". WEIGHT: 42 pounds.
.
AUDIO
30
www.americanradiohistory.com
.
.
.
SEPTEMBER, 1964
WAIT TILL YOU INSTALL A REVERE-WOLLENSAK TAPE DECK!
You're in for a musical revelation. In fact, you're in for several pleasant surprises when you see and hear the four different kinds
of Revere -Wollensak tape decks. Want to make your sound system the most convenient custom installation in the world? Install
one of the Revere -Wollensak AUTOMATIC Tape Decks that change tapes even more conveniently than an automatic record
changer changes records. Want to make your sound system the most professional and reliable custom installation? Then use
any of the three Wollensak reel -to -reel decks. You can't go wrong.
WHAT
Take your pick. At your nearest dealer. Reel -to -reel or automatic ...
YOU WANT IS A REVERE-WOLLENSAK!
WOLLENSAK 1780 STEREO TAPE DECK
For
the sound perfectionist who wants to incorporate top quality Wollensak stereo recording and
playback facilities in an existing sound system.
Can be installed either vertically or horizontally. Dual matched record /playback preamplifiers
automatic head demagnetizer
sound
with sound
instant pause control
cadmium steel enclosure with chrome trim
.
easy -to- operate tab controls
volume control for each channel
automatic shutoff
automatic tape lifters
many other outstanding stereo sound -on -tape features.
SIZE: 13%" x 14" x 51/2 ". WEIGHT: 15 pounds.
...
...
...
...
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.
WOLLENSAK 1281 STEREO TAPE DECK Now
you can have the many advantages of a fine
Wollensak amplified tape deck at a new low
price! The "1281" is a beautifully styled unit
that gives you true professional sound control:
4 track stereo and mono record and playback
2 VU
horizontal and vertical operation
meters
71/2 and 334 tape speeds
auto-
...
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...
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matic cut -off
convenient interlocking tab
controls ... instant pause control ... patented
self- adjusting braking system
independent
volume and tone controls on each channel
many, many more quality "custom" features.
SIZE: 101/4" x 155/e" x 5% ". WEIGHT: 20 pounds.
...
...
Circle 120 on Reader Service Card
AUDIO
SEPTEMBER, 1964
31
www.americanradiohistory.com
Demagnetizing Tape Heads -A Yardstick
HERMAN BURSTEIN
(Sole:
To facilitate a prompt reply,
please enclose a stamped, self- addressed
envelope with your question.)
Merman Burstein
280 Twin Lake E., Wantagh, N. Y.
thinness and hence reduction of the barrier between oxide layers. However, if
you are careful to record at moderate
levels, you may not notice the difference in
print- through.
Recording from TV
Tape Quality
The following is not a queston but a
commentary by one reader which may echo
the thoughts of other tape enthusiasts:
"I am primarily interested in classical
tapes, and feel that a well produced tape
cannot be excelled by any other source.
However, there are many deficiencies in
the duplication and production of such
tapes which should be corrected. Of my 50odd tapes, only about 10 can be played at
concert hall volume without considerable
background hiss. I believe that this is one
reason why dealers seldom demonstrate
their equipment with tapes. It is lamentable that such an otherwise superb source
should be plagued by this annoying defect.
There are now a number of fine tape machines on the market. What high fidelity
needs is new, superior techniques for the
production of tapes."
To this and other readers it may be
encouraging to note that there are new
low noise tapes coming into use which
may help to improve the signal -to-noise
ratio. Also, the new tape recorders used
by professionals are an order of magnitude better than previous machines. What
remains, is to find a better way of dupli-
cating tape.
Instrument Tape for Audio?
Q. Is instrumentation tape as good for
audio purposes as a first- quality audio
tape with respect to frequency response?
Also, how are the extended length tapes?
A. I cannot give you a definite answer
on the use of instrumentation tape for
audio purposes. A leading tape manufacturer has indicated to me that you may be
taking some chance in using such tape.
Tape is made optimum for each purpose,
such as audio, computation, telemetry,
and so on. A tape specifically for instrumentation, where it has to deal only with
pulses, might have excessive treble response and inadequate bass response. This
isn't certain, but quite possible. Also, it
might have physical properties-such as
immunity to squeal-that are not as appropriate for home tape recorders as for
instrumentation devices.
I don't know whether your second question pertains only to frequency response
or to all characteristics of extended length
tapes, Frequency response will be about
on a par with conventional tape. The main
disadvantage of such tapes appears to be
increased print -through because of their
Q. I have a new tape recorder and would
like to record from TV without using a
microphone. Please let me know how to do
this.
A. You can record from TV in three
ways: (1) The simplest is to connect a
cable to the two leads to the TV speaker;
(2) you can connect a cable to the "hot"
and ground leads of the TV volume control. This has the advantage of providing
a signal with better frequency response
and lower distortion than procedure 1,
and of keeping the signal level fed into
the tape recorder independent of the TV
volume control setting. However, if the
cable to the input of the tape recorder
is more than about two or three feet long,
there may be appreciable treble loss in the
recorded signal; (3) you can try to find
room on the TV chassis to install a cathode
follower. Connect the input of the cathode
follower to the TV volume control, and
feed the output of the cathode follower
to the tape recorder. Then you can use a
long cable between the TV and tape recorder.
Copy Hiss
Q. My question involves copying tapes,
using two Tandberg 64's. The problem
seems to be that I get too much tape hiss on
the tape copy. although the quality of the
copy is otherwise excellent. I have tried
several brands of tape, with more or less
the same results. I also have tried a bulk
eraser, but with no audible improvement. I
have tried various combinations of the gain
control settings of the two Tandbergs,
again without effect on the hiss. I have tried
recording at augmented levels (higher than
indicated appropriate by the magic eye),
but there is still more hiss on the copied
tape than on the original one.
A. Each time you copy a tape, the tape
hiss level rises about 3 db. This factor, inherent in the copying process and having
nothing to do with your particular machine,
accounts at least in part for the hiss you
complain of. The only suggestion I can
make, in line with your own thinking, is to
record at the highest practicable level, thus
maximizing the ratio between the audio
signal and the hiss of the newly recorded
tape. Bear in mind that commercial tapes
usually have a higher hiss level than home recorded tapes (because the former have
gone through several generations of copying), so that in copying the former you are
augmenting an already high hiss level.
Q. There has been considerable discussion on the importance of demagnetizing
the tape heads and guides. In general, this
process is recommended after every 8 to 10
hours of use. Little has been written, however, on the many factors that contribute
to building up the magnetization of the
heads and guides. These factors, it has been
asserted, may require demagnetization much
more frequently than every 8 to 10 hours.
For instance, the editing and indexing of
reels of tape requires the frequent use of
fast forward and rewind. The static electricity produced by the tape as it passes
swiftly in close proximity to the heads will
in many cases produce a sufficient field to
magnetize the heads. Switching the tape
machine on with the record selector in the
on position can cause a momentary power
surge to the record head, magnetizing it.
Frequent switching between record and
playback may have a similar effect, as
(possibly) will frequent switching between
quarter -track and half -track operation.
When we take into consideration that the
demagnetization process for a professional
tape recorder, if properly carried out, involves demagnetization of each of the 8, 4,
or 5 separate heads, each of the 3, 4, or 5
tape guides and lifting devices, the metal
stabilizer roller and tension arm, and other
parts, it can readily be understood that this
becomes a rather arduous task if performed
often. Therefore what the serious tape enthusiast requires is a meaningful yardstick
by which to judge his particular need for
demagnetization. This may be governed by
how frequently he engages in those practices which result in magnetization. Would
you kindly list and discuss the many factors that would be generally applicable to
the professional and semi -professional recorder with respect to magnetization and
demagnetization.
A. It seems that your letter provides me
with more information than I can offer in
return. About all I can say is that on the
basis of experience, a number of authoritative persons have concluded that the tape
heads and metal guides and other metal
parts contacted by the tape should be demagnetized at least after every 8 hours or
so of machine use. Some persons demagnetize oftener, for example after every 4
hours. If the heads have been exposed to a
sudden surge-for example if someone has
knocked over a microphone -they will demagnetize immediately or as soon as possible. It should be noted that some tape machines provide for self- demagnetization of
the heads. That is, current flowing through
the heads is allowed to die away slowly.
Even so, it does no harm to demagnetize
the heads regularly as an extra precaution.
And the tape guides still require demagnetization.
High -End Loss
Q. I have noticed a drop in the high -end
response of my tape recorder. Would substitution of metal film 1 per cent, 1 -watt
resistors and silver mica capacitors in the
equalization circuit help? Or is the trouble
a design error?
A. The equalization problem is probably
not a design error but may be due to
change in value of the resistors and capacitors in the equalization circuit. It will do
no harm to replace the capacitors and resistors involved. As a aide benefit, you may
get a reduction in noise as the result of
using metal film resistors. Furthermore,
keep in mind that the loss at the high end
may be due to excessive bias current, to a
worn playback head, or to poor tape -tohead contact (because of dirt, oxide, and
such on the heads).
Æ
AUDIO
32
www.americanradiohistory.com
SEPTEMBER, 1964
.....
Meet the new Royal Grenadier
world's most
perfect speaker system. Pretty soon every stereo
system 'round will be featuring this revolutionary divergent lens speaker system. The first loudspeaker
ever designed and engineered for stereophonic reproduction. Lets you sit anywhere-hear everything.
EMPIRE
Ctr.1e No. 108
www.americanradiohistory.com
cm
Reader Service Card.
As Featured At The World's Fair Pavilion of American Interiors
The New Empire Royal Grenadier
Divergent Lens Speaker System -Model 9000M
Model 9000M
1. 15" mass loaded woofer
outstanding features:
3.
4.
Years ahead in design and engineering the Grenadier projects a majestic sound
unlike any you've heard before. Its cylindrical shape creates a system relatively
free from room standing waves and approaches acoustically flat frequency response.
Sound level and tone remain constant virtually anywhere in the room. Its three
divergent acoustic lenses achieve unparalleled stereo separation. With the Empire
Grenadier
speaker placement becomes non -critical.
5.
6.
7.
8.
9.
...
10.
11.
12.
Bas.,
WALK
with floating
suspension and 4" voice coil.
absorbent rear loading.
Die -cast mid frequency -high frequency
full dispersion acoustic lens.
Hand rubbed satin walnut finish.
Imported Italian Perlata marble.
Ultra -sonic domed tweeter.
Full presence mid range direct radiator.
Exclusive non -resonant rigidized
heptagonal sonic column.
World's largest (18 lbs.) speaker
ceramic magnet structure.
Front loaded Horn -360° aperture throat.
Complete symmetry of design with
terminals concealed underneath.
Dimensions: height 29"
diameter 22 ".
2. Sound
-
Ind. Ihgh
AROUND
-,=
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Try this simple test.
You
will notice
no change in sound
level of bass, mid range, and highs. Full
frequency and separation is assured by
Empire's exclusive divergent acoustic
lens system.
Empire Grenadier model 8000
Started
a new era in speaker systems.
Measures 29" high with a 151/4" diameter. Its features are virtually the same
as the 9000 plus the exclusive Empire
Dynamic Bass Reflex
high Q reflex
tuned columns for in -phase low frequency reinforcement. The scientifically accurate gradients and vented
...
ports provide unbelievably enriched
Try this same test with any other brand
of speaker. Some speakers will only
have a narrow angle of high frequency
sound propagation. Some may have 2
or even 3 bands of high frequency
sound. With these or other speakers,
slight shifts of position, turning one's
head, or even leaning to one side may
cause sharp changes in the listening
tone and level. Not so with the Empire
Grenadier.
Acoustically engineered to let you sit anywhere
Grenadier is decorator- designed to fit any decor
modern
fit in corners or against walls.
...
- hear
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everything. The Empire
warm elegance to stark
Its satin walnut finish is designed to blend with all furnishings. An imported Italian
Perlata marble top is optional for added elegance on the model 9000. The Empire
Grenadier is a truly Beautiful and functional achievement in sight and sound.
base response.
For a sound demonstration of the
Empire family of "most perfect"
Empire 880P and 888PE Elliptical Cartridge
products, go 'round to your dealer or
write for complete literature.
EMI'IRE
'World's Most Perfect High Fidelity Components"
Empire Scientific Corp.
- 845
Magazine stated
-
tailor -made for console or equipment cabinets
the famous
Empire 398
outstanding -too handsomely finished to hide behind cabinet doors.
High Fidelity reports on the Troubador:
precision ergineered product of the
highest quality
one of the finest, handsomest record players available."
The model 498
-
...
.
"...
Stewart Ave., Garden City, L. I., N. Y. Export: EMEC, Plainview,
L. I., N. Y.
- Canada,
Circle No. 108 on Reader Service Card.
www.americanradiohistory.com
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lent
"...truly
excel -
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Frequency response 8 to 30,000 cps.
Compliance 20X 10 -6cm /dyne. Empire
880pe comes with a biradial elliptical
hand polished .2 X.9 mil diamond.
Empire Scientific Corp., Ltd., 1476 Eglington West, Toronto
A Basic Course in
Commercial Sound
NORMAN H. CROWHURST
Chapter VI
Microphones and speakers are ship, such that if a peak occurs,
both important to a successful it's there, no averaging possible.
Human hearing has a subconcommercial sound system, alautomatic equalization'
scious
though in somewhat different
If certain frequencies
feature.
ways. In one respect the microare
consistently
over-emphaphone is the more important : If
it picks up too much background
noise or reverberation, introduces bum, or distorts the sound
picked up in any way, it is difficult if not impossible to eradicate this elsewhere in the system. Let's consider the various
properties of microphones and
see how important they are.
Frequency Response
The frequency response of a
microphone must be smooth.
Lack of smoothness affects naturalness of sound; it affects
acoustic feedback problems and
associated effects to a greater extent than similar deviations in
individual speakers. It may also
cause undue distortion in the
amplifier, and it may make noise
(both electrical and acoustical)
more difficult to overcome.
The peakiness of a speaker's
response is usually associated
with some directivity effect a
peak on axis is somewhat compensated by less energy off axis
at that particular frequency, so
the total sound field averages out
a bit. A microphone cannot do
this. The sound source and microphone are in a fixed relation-
(B)
:
AUDIO
directivity patterns for
omnidirectional; (B) biunidirectional or cardioid.
Basic
microphones: (A)
Fig.
6 -1.
directional;
(C)
sized, the ear gets to ignore this
fact after a short while, so the
speaker is `excused' this fault.
Amplifiers are not equipped for
such excusing.' A microphone
peak at one frequency may result
in overload at that frequency,
when other frequencies are well
below overload level. While certain voice frequencies may
`blast' the system, the remainder
of the same person's audio spectrum may seem inadequate for
the system something for
which only the mike can be
1,!.(ined (unless the individual
has a strident voice naturally).
For acoustic feedback, intensity at the offending frequency
has to be excessive only at the
point in space occupied by the
mike, for a howl to start. A similar peak in one, or even all
speakers, results in more energy
going into the room at that frequency, but the effect may aver age out to some extent, because
of the complicated standing wave
field generated. In short, the deopment of standing waves
tends to disguise the speakers'
abnormalities in frequency response, but aggravates the same
thing in the microphone.
-
Directivity
A speaker sends out sound
waves into a four -dimensional
35
SEPTEMBER, 1964
www.americanradiohistory.com
world of acoustic space -three
dimensional waves fluctuating
with time ; sound going into a
microphone enters a two- dimensional world-magnitude fluctuating with time. The acoustic
wave enters a `public domain,'
the electrical wave is strictly
`channeled.' So directivity, to
control the way in which the electrical wave is derived from the
four dimensional world surrounding the microphone, can be
very important.
Among the simpler microphone designs there are three
types of directivity : (1) omnidirectional, which means it picks
up uniformly well in all directions ; (2) bidirectional, which
means there are two directions
of concentrated pickup ; and (3)
unidirectional, a single direction
of concentrated pickup (Fig.
6 -1). Note that the usable area in
front of a unidirectional type is
wider than that in front of the
bidirectional.
The omnidirectional is best for
random, or general pickup, because it has no "dead
dead spots."
Both bidirectional and unidirectional are better, each in its own
way, for selective pickup. As well
as allowing pickup from a
greater distance, each reduces
unwanted pickup and helps with
acoustic feedback problems.
Which type is the better to use
varies with circumstances.
For dialogue, the bidirectional
is useful, because it can be placed
between the persons conversing,
so each has his own `live spot.'
The participants do not have to
adopt a cheek -to -cheek attitude,
but can look at each other. However, if they are following a
script, the cheek -to -cheek position may be more convenient
(they can both read the script,
held or supported `behind' the
mike), using a unidirectional
mike.
For a single person speaking,
the unidirectional is indisputably
the best choice. It allows him
more freedom of movement without his getting " off mike," and
gives much greater pickup range
than the omnidirectional. For
numbers of people in conversation-plays and the like -one
has the choice of individual unidirectional mikes, an omnidirectional mike for the whole group,
or an intermediate number of
bidirectionals. Each has its advantages, and has to be used
with techniques peculiar to it, for
best results.
Probably the single omnidirectional mike-or for a large
area a few of them-gives the
greatest flexibility. But omnidirectionals can only be used where
no problem with background
Fig. 6 -2. Where directional mikes
used, they should be separated
are
far
enough apart to prevent overlap of their
effect pickup areas. Then spaces between, where there is virtually no pickup
(and what there is will have poor quality) should be avoided.
noise or acoustic feedback exists.
They have greater flexibility because there is no `overlap' problem, providing they are correctly
phased, where more than one is
used. Numbers of either bidirec-
tional or unidirectional mikes
(particularly the bidirectionals)
can lead to overlap problems
certain spots where more than
one unit is picking up.
In general bidirectional or
unidirectional mikes should be
spaced widely enough apart that
their pickup fields do not materially overlap, and the participants should avoid use of those
spots that are not adequately
covered by any one mike (Fig.
6 -2). A big help where excessive
background or acoustic feedback
is a problem, is the use of the
electronic quick -fade system, al-
-
36
lowing only one mike in use at
each instant to be `live'. This we
will cover later.
A trick with bidirectional
mikes that has not been used as
much as it might be is very useful for amateur presentations : a
prompter or director can occupy
a ' dead spot' in the acoustic
pickup field and give verbal di-
rections or prompts that are
quite audible to the participants
but not to the microphones. For
stage presentations, such silent'
positions can also be camouflaged visually, so the prompter
or director can be right in the
middle of things without being
either seen or heard by the audience. At first it may be difficult
for the players to realize that he
is not only invisible but also inaudible to the audience, but once
this is realized it can be a very
useful trick.
In addition to the more common directivity patterns (Fig.
6 -1), there are some speciallydeveloped microphones with
exaggerated unidirectional pickup patterns. They are more
bulky than standard types, but
this is no disadvantage, because
of their enormously greater
range, enabling them to be placed
out of sight. One very important
thing about them: they must not
be obstructed in any way.
I remember one occasion
where a store in a noisy location
was being pressed into service
as a studio for making a short
TV film. Knowing my experience
with commercial sound, the director called me to know what
could be done to eliminate the
background, short of acoustic
treatment of the place, for which
there wasn't time. I recommended use of one of these
super-directional mikes and put
him in touch with a studio who
could lend him one.
After some hours, he called to
say he was still having troubles.
I went round to investigate and
found the mike flanked by a cardboard reflecting cone, to ' augment its effect' (Fig. 6 -3). I
AUDIO
www.americanradiohistory.com
SEPTEMBER, 1964
asked if the mike had been tried
by itself without this addition.
No, he thought it would be
needed, because background
noise was so high, so he just
went ahead and put it on, `to
save time'.
It took some persuading to get
him to remove his ingenious reflectors'. When he eventually did,
he found the microphone's designer had done a good job ; he
successfully got his pickup, with
very little background interference. So don't try to improve on
the work of acoustic designers
especially in dealing with microphones -it's a specialized job
and they know how to build a
mike to do its job right without
extraneous help.
-
The condenser or capacitor type
invariably carries the highest
price tag and many think this
means it has the highest quality,
which is not necessarily true.
More important than which
type of transducer it is, are the
questions relating to how well it
fits into the system in various
ways. Each has certain characteristics of impedance and level,
variety of patterns available (in
directivity) and quality and stability of frequency response.
For many years the best omnidirectional mikes were of the
condenser type, but their high
cost is not related to their su-
Phasing
This doesn't normally arise
with microphones, because usually only one mike picks up any
one sound. But in some commercial sound systems, where
reliability is extremely vital, the
customer may require a standby
microphone in position, as a
safeguard against microphone
failure in the middle of a program. If the standby mike is left
inoperative until needed, there
is still no phasing problem. But
if both mikes are `live' at once,
phasing is important, whatever
type of mike is used. Incorrect
phasing will cause partial cancellation at some frequencies, resulting in a very peculiar sound
quality.
This is also true where mikes
are more widely spaced, if overlap of pickup area occurs.
Type of Microphone
Not a few professional people,
who have no knowledge of circuits, judge microphones entirely
by type moving coil, ribbon,
condenser (or capacitor), crystal
(or ceramic), or "magnetic"
(also known by various other
names, such as `moving iron',
`variable reluctance ', and so on).
:
AUDIO
Fig. 6-3. A mistake not to be made in
using superdirectional mikes. The dashed
lines represent a cardboard cone that an
uninformed enthusiast put around it to
'help'; actually, presence of the cone destroys the mikes natural high directivity.
perior performance. The main
reason for the higher cost is the
associated equipment : polarizing supply and head amplifier or
impedance changer, in miniaturized form, that have to be attached to the mike. On most
scores, all this extra electronics,
hanging onto the mike, is a disadvantage rather than a merit.
In the same early days, the
only kind of directional mike was
the ribbon, which was approximately bidirectional. Its clumsiness made its quality poor, but
its directivity, where needed,
outweighed its quality deficiency. Modern ribbons may be
either bidirectional or unidirectional, and their quality is second to none. Intrinsically they
are more fragile than other
SEPTEMBER, 1964
types, but a ruggedly designed
ribbon can be better in this respect than a poorly designed
mike of any other type.
In recent years, moving coil
mikes (which were the poor relations in the early days) have
approached the performance
(providing you get a good one)
of condenser types at very much
lower cost and with much greater
reliability. They were among the
early entrants for unidirectional
(also known as cardioid) and
were not very good at first. But
later models achieve extremely
good response, with a good directivity pattern to go with it.
Crystals, or the more recent
ceramics, are much less costly
than moving coils and generally
inferior in performance, although high in sensitivity. But
some of them are quite good and
a good ceramic may easily be a
`best buy' for systems in which
they can be used. Again, there is
no definite relationship between
quality and cost, although usually the superior engineering
which results in better quality
will demand a higher price.
Magnetic, or whatever other
name it goes by, is almost inherently an inferior type, but it has
the advantage of high sensitivity which makes it attractive
(like the low cost ceramics in
this respect) for low cost, small
installations.
Virtually all types of microphone are now made with all
types of directivity pattern, although there are strong trends
to stay with the pattern more or
less natural to a type. Most of
the inexpensive types are virtually omnidirectional, although
the frequency response is much
better from the front. Inexpensive bidirectional (ribbons) are
reasonably good -they cannot
help having their characteristic
figure 8 pattern. Cheap cardioids
are usually a poor buy : their
frequency response is poor and
the rejection at the back very erratic in frequency characteristic.
37
www.americanradiohistory.com
Hi
Question, Chapter VI
So much for types in general. Next installment will go
through the question of impedances and methods of connection and various other aspects of input circuits. The
best systems will demand a
professional microphone,
which invariably costs more,
while smaller systems can
adequately use a less expensive type. Is the principal
distinction one of (a) quality
(frequency response, and so
on), (b) impedance of con nection, or both?
Answer -Chapter VI
A professional microphone
(unless it is a cheap one for
hich the advertising merely
ciai,us it to be professional,
which does happen) has both
these differences. Its frequency response is closely
controlled -every unit made
will have its response
checked to a standard before
it
is allowed to leave the fac-
tory -so it will invariably be
smoother than the less expensive model even though
t he two look almost identical.
It will also have more rugged
termination and standard
connectors of one or other
professional variety (usually to customers' requirement,
but most manufacturers have
their own standard where
the customer does not specify). All professional mikes
have an output impedance of
one or other standard line
rating, while non- professional mikes are either low or
high. Some mikes, to bridge
the market, have alternative
impedances, including line as
well as high and low. All this
we will discuss more fully in
the next installment.
Fi
and the British:
Privacy
ALAN WATLI NG
CR
nOME BEING OUR CASTLE, be it
country mansion or semi -detached
(a typically British word meaning a
house sharing a paper -thin wall with another one), a tremendous value is put on
Privacy. A motto might well be hung on
every wall; "Thou shalt not hear thy
neighbour's Woofer" -or his TV, or his
madrigal session, depending on the district. We have yet to extend this tribal
taboo to the Great Outdoors, as transistor portables now invade our park,
beaches and other marital hunting
grounds. Fear not, it will be done. If only
by the judicious use of transistorized
signal generators hidden in picnic
baskets.
As we have a small island and rather
a lot of semi -detacheds, the proportion of
enthusiasts who can afford the luxury of
actually using fifty American watts is
also small. We have, therefore, a native
interest in reducing Resonance in Hollow
Floors, Chestiness, and Ear- piercing
Top. The emphasis this year is on mini speakers and Cassius cabinets (with the
lean and hungry look). On the credit
side, this gracious way of living encourages sensitive speakers for low outputs,
"open" sound and a pathological hatred
of Boom. The glorious prospect of per-
O
p'
Open Sound
use of both of these will eliminate neighbour crosstalk -and the need for the
other knobs.
So now you've sent us Background
Music. Yes, you, with the American accent. This mental wallpaper attacks privacy on a bold non-partisan front. Eat
out, you get it. Shop in the big stores,
you get it. Go to the airport to flee, you
get it. A treacly, predigested, non-stop,
meandering threshold level of paperback
pulp on slow -slow tape drips from the
wall- boxes. When there used to be a
restaurant orchestra at least you had the
thrill of waiting for the violinist to dip
his bow in the gravy. Now there's only
the forlorn hope that the 4800 feet of
four -track .Mylar will wrap itself around
the capstan.
L
Resonance
sonal Arctic isolation has bounced headphone sales
started this way in my
high chair and have a daguerrotype to
prove it -and some people now actually
claims to hear what is coming out of their
amplifiers. Cynicism will get you nowhere, say you . . . There should be a
knob, say T, marked "% Distrust," and
another marked "Absence." Intelligent
-I
Now that sounds a trifle bitter. Perhaps it's because I'm using my neigh hour's typewriter and he is a schoolteacher. They just don't understand the
need for mass anaesthesia.
Reverting to the topic, the original
fear that stereo would blast away the
remaining bricks that separated us front
the next door has not been realized. For
one thing, operating each speaker at half
the level has been kinder to the eigentones that worried its when all the watts
were coming from one corner. For another, many of us (not all, by any
means) have found that directional
speakers give more accurate stereo positioning. Ergo, less splashing around of
the Brahms. For yet another, it has been
proved conclusively that for the best
stereo effect your chair most be arranged
in a triangle and the room must be asymmetrical with no doors.
And what could be more private than
1£
that?
AUDIO
38
www.americanradiohistory.com
SEPTEMBER, 1964
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AUDIO
39
SEPTEMBER, 1964
www.americanradiohistory.com
RECORD REVUE
Edward Tatnall Canby *
4;01111141
)
DISC CUTTING -1950-64
Haydn: Orfeo ed Euridice (L'anima
del filosofo). Handt, Hellwig, Poell
et al.; Chorus, Orch. Vienna State
Opera, Swarowsky.
Vox OPBX 193 (3) mono
It was a very enlightened self -interest
that prompted Vox to reissue this six sided mono opera LP after some 14
years, the only recording ever made of
Haydn's late and unperformed masterpiece of 1791, his last opera. The tapes
are those of the Haydn Society, made in
1950 after long and extensive research
to assemble the fragments of the opera. I
have the original Haydn Society discs,
long since out of print -I've made AB
comparisons and am amazed. From the
very same tapes, the Vox discs are extraordinarily improved, reflecting the immense strides in the technique of disc
cutting since 1950.
We've always known that our early
tapes were mostly far ahead of the LP
discs that could be made from them.
Here, the difference is audibly measurable. Many an innovation since 1950
adds cumulatively to Vox's triumph with
this unusual album. For instance, variable groove spacing "shortens" Vox's
sides, allowing a higher recorded level
(as I found by direct comparison)
while reducing the inner -groove problem. The 1964 surfaces are astonishingly
improved, too, velvety -silent compared
with the pops and clicks of the old
discs. (Do these grow worse with time
on an unplayed disc? An interesting
question which might apply here.)
But more important is the astonishing improvement in the over -all "fi" on
the new discs. On the original records
the solo voices sound harsh and edgy
throughout, especially the all-important
voice of the tenor solo, Orpheus. On the
new discs he is magically transformed.
The vocal sound is now soft, natural,
virtually distortionless even in the loudest passages.
This significant difference would seem
to be largely that of intermodulation
generated in the old cutting, perhaps
with other distortions mixed in. Was the
hot stylus in use as early as 1950 -51 ??
Probably not in the Haydn Society cutters We have here, I'd guess, an accurate reflection of the then still unsettled microgroove cutting process, not
yet well controlled after the changeover
from the relatively coarse 78 cutting of
the past.
Other minor details help the new
discs -RIAA curve (the old discs are
clearly cut to a different curve), raised edge lead -ins (in 1951 not yet introduced
by RCA), protective inner sleeves (the
old discs were shipped out naked In
their pockets). A lovely price differential too, of course. Vox has retained the
gist of the enormous Haydn Society
booklet, including the complete libretto
in Italian and English.
!
HIGH BAROQUE
Handel: Water Music (complete, ed. Boy ling). Bath Festival Orch., Menuhin.
Angel S 36173 stereo
Händel: Wassermusik (complete, ed. Arnold). Berlin Philharmonic, Kubelik.
D. Grammophon 138799 stereo
We must credit the LP record with having
rediscovered the complete Handel Water Music, a dozen and a half pieces covering two
full microgroove sides. The LP is voracious.
Previously, the numerous "Water Music
Suites" taken from the complete work centered upon only six movements. short enough
for a modern symphony-concert item or for
a 78 rpm album. No good on LP So here are
the two latest complete stereo versions, enough
music to fill two sides nicely. One is from
nterrie England, the other straight out of
Berlin, with a Czech -born conductor. Nice
contrast.
They are mostly the sanie in content but
not quite. No score exists of the original
and when. It isn't absolutely sure upon what
watery occasion the music was played for
King George from a barge floating in the
Thames river. Handel revamped the score, as
he often did, for later uses of varying sorts.
Indeed. four movements were borrowed from
previous works of his.)
The instrumentation is far from definite,
either. The erstwhile suites of six movements
were rewritten to suit the modern symphony
orchestra ; Sir Hamilton Harty's was the best
version. (Others, I'd guess, were just different
enough to avoid copyright problems.) Handel
changed his own original, fixing it up economically for dry -land use. (He added a harp sichord -or -organ continuo part, there being no
harpsichords and organs on river barges.)
Still further, there were customary ad lib
cadenzas, inserted by the performers. (You'll
find some in these recordings. Very nice.) And
our new understanding of Baroque rhythms
has led to some drastic changes in the
"French overture" opening movement, as
heard in both these versions. Double -dotted.
All in all, what with varying ideas as to the
assorted dance -rhythm tempos, depending on
the conductor, each new "Complete Water
Music" is a law unto itself. Never know what
you'll find.
The German recording here is the more
polished, the more accurate in performing ensemble, rather intense and driving in the big
movements, lovely in the slow parts. It's from
a late -Eighteenth century edition. The British
version, under that Britisher -by- adoption, Yehudi Menuhin, is more intimate and a trace
stiff in the playing, very slightly ragged in
ensemble here and there. But the dance
rhythms are hearty, especially in such British style Handelian dances as the Hornpipe,
which will be forever a bit beyond a German
player's ear It is a drier, closer recording
than the mellow Deutsche Grammophon of
fering.
!
-if
(
!
Handel: Four Concertos with Oboe. Cento
Soli Orch., Anthony Bernard.
Nonesuch H -71013 stereo
These new Nonesuch low- priced LPs (from
Elektra) come in stereo or mono at the same
price. That makes the stereo a special bargain,
40
with the one-dollar premium removed. (Big
companies still hold out but a number of the
enterprising lesser -sized outfits are coming
over to the one-price system. Stereo users
please note.)
Handel was the most British composer
imaginable, out of his own sheer cleverness.
And so it is always interesting to hear his
music performed by continental players. This
is a fine French orchestra, heard before on
records (notably on Omega stereo around
1959). It plays with crisp and business -like
intensity, with the characteristic bright
French string sound and sharp -edged woodwind tones. Lots of expression but not a bit
sentimental. A pleasure after much British based Handel.
Bach: Magnificat in D. Stich -Randall,
Casoni, Bottazzo, Littasy, Cho. (and Orch.)
Sarrebruck Conservatory, Schmolzi.
Bach: Cantata No. 51, "Jauchzet Gott."
Teresa Stich -Randall, Chamber Orch. of
the Sarre, Ristenpart.
Nonesuch H -71011 stereo
Here are two really first -rate recordings
of Bach at a bargain price, mixed German Italian performances from the Sarre, on the
borders of France. (The tapes are French.)
The famous cantata for solo soprano, No.
51, features a brilliant trumpet obbligato
pitted against the solo voice. It is sung here
with astonishing expertise and musical perception by the excellent Teresa Stich -Randall, who can turn on, whenever she wishes,
that curious "little boy" tone that we find
among German sopranos (notably Irmgard
Seefried) -each note sung precisely on pitch
and with virtually no vibrato at all. She can
run off rows and rows of rapid scales and
arpeggios, too, with instrumental precision
to match the trumpet part and a pair of solo
violins. Exactly what is needed the music
was composed for a boy soprano.
The "Magnificat" is a lively, sincere performance with a fine student chorus (sounds
like boys' voices on top) and a well- balanced
group of soloists, all musical and only moderately clumsy (who isn't ?) in the difficult
vocal parts. Few better Bach recordings at
any price, I'd say.
:
Bach: Cantata No. 51, "Jauchzet Gott ";
Suite No. 1 in C. Judith Raskin; Festival
Orch. of N. Y., Thomas Dunn.
Decca DL 710089 stereo
Here's a New York performance of the same
cantata, coupled with the Suite No. 1 for
orchestra. Both are subtlely New York in
style -how quickly the New York way of performance tags itself on records in contrast to
continental ways of music -making!
New York playing (and singing) is relatively tense, hard, high-strung, Its teeth a bit
on edge. There is a curious sense of hurry
(even when the music is slow), an inner tension that is not in the music but in the players.
Thus though the Cantata is well played and
well sung, if without much inner perception,
it somehow has a bit of the hard New York
drive to it and the orchestral Suite has mnch
more of the same. No poetry. Judith Raskin
is an excellent modern soprano who sings the
AUDIO
www.americanradiohistory.com
SEPTEMBER, 1964
incredibly demanding runs and roulades, the
long- breathed phrases of Bach's vocal line
with competence and good musicianship but
with no special talent for this very special
kind of vocal music. Her main trouble, entirely normal, is a vibrato that blurs the intended accuracy of the rapid notes and spoils
the duet -like play between solo voice and solo
instruments.
Stich-Randall, on Nonesuch (above) does it
superb re- creation of the Bach
much better
"Believe it or not,
I make over 90% of
Telemann: Concerto Grossi No. 1 & 2Overture. Orch. of the Sarre, Ristenpart.
Counterpoint- Esoteric 5612 stereo
my broadcast tapes
on the same Norelco
model designed for
your home,"
says Skip Weshner
-a
style itself.
She sings rings and rousinging
lades around Raskin.
Bach: Violin Concertos Nos. 1 & 2; Double
Violin Concerto. C. Croulnik, G. Armand,
vis., Toulouse Symphony, Auriacombe.
Counterpoint-Esoteric 5610 stereo
The first of this pair has more of the excellent Sarre music- making under Ristenpart,
on a different label. Unusually well played
Telemann and nicely recorded too. The second
disc offers some good Bach, if a bit heavy handed for today's nervous tastes, by two
fiddlers and an orchestra quite unknown to
us hereabouts and a conductor the same.
Probably very well known in their home
country. A lot of recorded pleasure here for
a modest price.
Now if only Everest -Counterpoint- Esoteric
(all the same company) would get somebody
to fix up their labels and jackets It's con.
and
certi grossi, not concerto grossi
the proper term is either the old Ouverture
or else the now -common Suite for Orchestra.
And one customarily gives the key of the
piece, like for instance E minor or what have you. (I.e. the Concerto in D Minor for
Two Violins.) 'Nuf said. The music here is
ies' fine and dandy.
!
Three Gamba Sonatas. Milton
Thomas, viola, Georgia Akst, piano
Bach:
Concert -Disc CS 242 stereo
Should Bach be played on the "wrong" instruments? Well, it all depends.
Here we have a viola subbing for the
original viola da gamba (a bigger, cello -sized
instrument with a high tenor voice) and a
piano taking on the harpsichord role. What
matters first, of course is the musicianship
of the performers and here there can be
no complaint. They both play Bach very musically, with good understanding of harmonies
and rhythms.
And yet-for those who know the original
sounds there are unpleasant side -effects. Inevitably, the piano sounds bouncy, percussive
and thin. It always does in such music. The
viola is much better, since Its tone is only
moderately unlike that of the gamba. In the
over -all, there is a shallowness of tonal impact, an unevenness, that is not good.
The original sound, with harpsichord, is
much bigger. broader and, above all, smoother
with a blending of the two instruments, where
here they compete tonally. And, inevitably
too. there are the casual wrongnesses of ornamentation that go with piano Bach and
more or less have to -since the piano doesn't
sound right in the Baroque-style turns and
trills.
Bach is big. He'll survive all sorts of transcribing and arranging, as we know. He survives very nicely here.
MIDDLE BAROQUE
Baroque Music in Salzburg. (Heinrich
Biber, Georg Muffat.) Contenus Musicus, Vienna.
Bach Guild BGS 70652 stereo
Funny how our increasing interest in older
music brings out "unknown" composers like,
say, this man Biber ( "Bee- bare "), whose
name I had never even heard until a year or
so ago when Cambridge Records brought out
the splendid album of his "Scordatura" violin
sonatas (i.e. with violin tuned abnormally).
(Continued on page 58)
AUDIO
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used. It handles tape more gently, too:
it doesn't break tape, it doesn't spill
tape, it doesn't stretch tape -not even
the half -mil stuff I'm forced to use to
get an hour's broadcast on a 7" reel.
"Although the '401' was designed for
the operating convenience and for the
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The Norelco Continental '401': 100% transistorized
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4 -track stereo /mono, record /playback
pletely self- contained with dual preamps, dual power
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At your hi -fi dealer's -or write to Dept. A -9, North
American Philips Company, inc., High Fidelity Products
Division, 100 East 42nd Street, New York, N. Y. 10017
Circle 122 on Reader Service Card
41
SEPTEMBER, 1964
www.americanradiohistory.com
Good -bye thread -up problems!
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42
AUDIO
'
SEPTEMBER, 1964
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securely. And the reel is new, too -fits all reel -to -reel recorders. Only 3" reel
available that holds full 600' of triple length tape (an hour recording time
at 3% ips). 150' and 300' lengths also offered. Look for the new "mailbox" display at your dealer.
magnetic Products Division
"SCOTCH" AND THE PLAID DESIGN
ARE REG. TMS OF 3M CO.. 5T. PAUL.
3rirli
COMPANY
MINN. 55119. 019E4.
4M CO
Circle 123 on Reader Service Card
AUDIO
43
SEPTEMBER, 1964
www.americanradiohistory.com
JAll and all that
Bertram Stanleigh
Mexican Folk Songs
At Mastertone Studios, just off
of New York's Times Square, I recently looked in on a recording session of Monitor Records, a firm
whose reputation is based on its
catalog of international folk music.
A collection of popular Mexican
folk songs was in the process of being committed to tape, with Maria
Luisa Buchino as soloist. Senorita
Buchino and her trio had already
waxed two successful Latin American platters for Monitor, and a
Mexican disc was scheduled with the
same forces. When the well known
guitar trio, Los Aguilillas, arrived
in New York on a concert tour, it
was decided this group would be
used in the project. The sounds
emerging from the monitor speakers when I arrived, were a strong
confirmation of the suitability of
this instrumental contingent.
During my visit to the session,
four songs were recorded : Guadalajara, La Media Vuelta, Nunca, and
El Son de la Negra. In three of
these, Senorita Buchino was accompanied by a quartet of guitars
and a guitarron (a bass guitar
which I had previously encountered
in the same studios at an Elektra
session). For the fourth number,
one of the guitars was replaced by a
Fig.
44
1.
smaller instrument of the same
shape, called a raquinto, whose
sound was somewhat like that of a
mandolin. Other tracks, recorded
before my arrival, included a small
Mexican harp, and a subsequent
session was to include a trumpet
and fiddel in the accompaniment.
Two recorders were in operation, a two -track and a three -track
Ampex. The two-track tape is used
as a master, and the three -track
version is retained as a safety, in
the event that later listening determines a need for rebalancing.
Four microphones were used, Neumann U -67's for Miss Buchino's
voice and the voices of the guitarists, who also provided the chorus,
an RCA 44 BX ribbon to provide
good low -frequency response and a
mellow quality for the four guitars,
and a Schoeps M221 picked up the
sound of the guitarron. Additional
echo for the voices and the guitars
was provided via an EMT reverberation unit. The group was deployed in a triangular formation
with the soloist approximately ten
feet from each of the instrumental
units, and the guitars and guitar ron about six feet apart (See Fig.
1.)
Mrs.
Rose
maintained
Rubin of Monitor
watchful supervision,
Miss Buchino sings, accompanied by Los Aguilillas and guitarron.
while A & R chief, Michael Stillman, directed the session. The engineer was Sid Feldman. Maria
Luisa Buchino was in fine voice, the
instrumentalists worked smoothly
together, and Sid Feldman managed to achieve a sound balance
that pleased all parties. There was
no feeling of rush; indeed, the easy,
relaxed pace at which everything
proceeded made me curious as to
the number of sessions they expected to employ. Stillman assured
me that two would suffice, and Mrs.
Rubin added the information that
in all of his recordings, both here
and abroad, Stillman had never required more than two sessions to
complete a platter -with no compromise in standards.
As the session continued, it became clear that Stillman's unhurried manner was based on a
thorough knowledge of his performers and their music. Nothing escaped his attention, but his affable
manner kept everyone in a happy
frame of mind, and prevented the
jitters that often result in clumsy
openings or ragged endings. Except
in those instances when a start was
poor, he allowed each take to go on
until its conclusion, or until the performers themselves called a halt.
His philosophy was summed up
when he said, "Let them do it their
way; they know best." Actually it
was Stillman who knew best, and
his skill in getting his message across
is an important contribution to this
forthcoming platter. Rather than
interrupt a poor take, he waited
until the next take was to start,
then gently suggested that the musicians retune.
My interest in this session was
particularly keen because this was
my first chance to hear Mastertone's
large studio since it had been renovated. Previously this had been an
extremely dead chamber, lined on
ceiling and all walls with glass wool.
It had been decided that a more
live sound was desirable, and the
walls had been relined with an array
of wood and cloth- covered glass
wool panels that can be interchanged
to vary the rate of absorption.
Special acoustical panels were used
on the ceiling. One auditioning is
hardly adequate for making a firm
judgment, but it is clear that there
is a more spacious quality, better
instrumental definition and a more
solid feeling to the bass.
While the final test of both the
sonies and the performances must
wait the arrival of the finished disc,
the impressions gained from playbacks at the session suggest that
Monitor has another success on its
hands.
AUDIO
SEPTEMBER, 1964
JAZZ REVIEWS
Duke Ellington & Billy Strayhorn: Great
Times!
Riverside Mono 475
Recorded in 1950 by Duke's son Mercer and
critic Leonard Feather, these piano duets are
a rare and rewarding bit of Ellingtonia that
will be prized by all collectors. Indeed, eight
of these selections were originally available
on the short lived Mercer label as a ten -inch
long player that has since become a valuable
rarity. The performances represent the intimate collaboration of two men who have
worked together since the late thirties. With
the exception of Tonk, all of the numbers are
strict improvisation without any advance
planning, but they have about them the close
knit, smoothly worked out detail generally
confined to meticulous arrangements. No
doubt much of this result is due to the pieces
chosen. They represent many of the outstanding achievements of the Ellington -Strahorn
team : Cottontail, C Jam Blues, Perdido, Take
The `A' Train and Blues for Blanton. But
there is none of the quality of four hand arrangements of orchestral pieces about these
performances. These are fresh, original approaches to these old standbys. The problem
of reissuing this material was considerably
more difficult than the usual procedure with
modern taped performances. Most of the original tapes had been destroyed by fire. Metal
mothers supplied some of the numbers, others
were dubbed from borrowed pressings of the
original release. The result may be slightly
less than super high fidelity, but quality is
entirely satisfactory.
studio control room where the
progoammes are passed through a
QUAD control unit for special balA
an.irg
BRITISH
Quality Check (Room. Programmes
originating from abroad are here
passed through a QUAD control unit
and power amplifier where they are
filtered and balanced for optimum
qua'ity prior to transmission.
The Double Six of Paris Sing Ray Charles
Philips Stereo PHS 600-141
Backed by the lively Jerome Richardson
Quartet, the Double Six offers eleven tunes
that have been associated with blues singer
Ray Charles
rather contrived gimmick on
which to assemble an 1p, particularly since
there is hardly a close relationship between
the styles of Mr. Charles and the Double Six.
Happily, Ray Charles has included a substantial group of material in his repertoire
that is well suited to the ministration of the
Double Six. Among their offerings are One
Mint Julep, Yes, Indeed, Georgia on My Mind,
Hit the Road, Jack and Ruby. In each number
the group employs its now familiar technique
of employing its voices as though they were
instruments, with words largely replaced by
scat syllables. Generally the title of the tune
is sung in English with the balance of the
lyrics consisting of dooh -wah dooh -wah. The
arrangements have been carefully tailored to
show of the technique and musicianship of
the talented Frenchmen, some of whom are
also members of the Swingle Singers. It is
quite possible that the present record will
take off and achieve the same widespread
recognition as the recent Swingle hits. The
recording quality is on a par with the vocal
technique-perfect.
-a
Bola Sete: Tour de Force
Fantasy Mono 3358
Brazilian guitarist, Bola Sete. whose appearances with both jazz and bossa nova
groups has already demonstrated his versatility, is represented in a solo recital that runs
the entire gamut of Western music. A Bach
Bourée, Henry Mancini's Moon River, Dizzy'
Gillespie's Tour de Force, Luis Bonfa's Samba
de Orpheu and Isaac Albeniz' Arturiaa are
just five of the ten numbers that make up
this recital. In spite of the variety of material, Sete's strong musical personality is
dominant, and there is a satisfying feeling of
unity about this disc. An able, rather than
phenomenal technician, Bola Sete is one of
those rare musicians who plays as naturally
as he breathes. No detail ever obscures the
overall design of his performances. Never is
there a rhythmic lag, yet there is a feeling of
poise, almost of hesitation at many points in
these performances that contribute greatly to
their elegance. This is a record that grows
in one's estimation with each replaying. As
in all waxings of unamplified guitar, there are
some minor mechanical sounds, but careful
mike placement has minimized their intrusion.
AUDIO
BROADCASTING
Britain and many leading
European countries several thousands of QUAD products help to
provide the best in broadcasting
and recording. This same equipment is used in many more
thousands of homes where people
listen to music.
In
Ask for full details of the QUAD range.
off the air monitoing. QUAD tuners
provides continuous check on transmission.
for the closest approach
to the
original sound
Tite Quality Monitor room. A final
check on the overall quality of British
Broadcasting.
Photographs by kind cooperation of the British Broadcasting Corporation
.and
in
your own
home, too,
the closest
approach
to the
original
sound.
THE ACOUSTICAL
MANUFACTURING
CO. LTD.
Huntingdon, England.
Circle 124 on Reader Service Card
SEPTEMBER, 1964
45
www.americanradiohistory.com
EQUI PAilEN'r
®
.0
0 0
OD
O
PRQFI I.E
AMPEX PORTABLE STEREO
TAPE RECORDER, MODEL 2070
The Ampex Model 2070 is a self-con-
tained stereo reel-to -reel tape recorder
designed to offer the easy- loading convenience of a cartridge machine with the
flexibility of a reel -to -reel machine. In
addition there are several technical innovations which stake this machine interesting from any viewpoint.
The first, and most striking feature, is
automatic threading. One glance at the
top of the machine reveals that there
appears to he space for only one reel; in
the place where the take -up reel would
normally he we see a flat surface with a
slot in it. The clever visual design points
the way one merely takes the tape from
the supply reel, places it in front of the
head as usual, then places it in the slot,
and the machine does the rest. Not only
does it thread itself on the special reel
concealed beneath that flat surface, but
the machine will automatically reverse
the tape direction at the end of the reel,
or whenerer pan want it to! And then, if
you want it to, it will shut itself off.
The reversing command is placed on
the tape by the machine itself and consists of a low- frequency tone which sets
off a chain of circumstances which ends
up by reversing the motor. Yes the motor
is electrically reversible. The built -iu
low- frequency oscillator may be actuated
to place its command signal anywhere
you desire on the tape.
As far as ease of operation i> concerned, we must admit that the 207( laud
its 2000 series faultily) is the easiest to
:
operate we have experienced in some
time. It can be operated easily with one
hand. The only thing we found fault
with is that there is no indicator to show
when the machine is on or off. The machine is turned on by lifting the tone
control knob about 1/4 -in. Unfortunately,
because of the handsome visual design,
it is very easy to overlook the fact that
the knob is raised, and there is no other
visual indicator of on- or- offness.
Although the 2070 plays hack, mono or
stereo, in either direction, it records in
the forward direction only. It uses three
heads to record 4 -track stereo or mono
and play it back. Head one is for playing hack tracks 2 and 4 (reverse direction), head two is the erase head, head
three plays back tracks 1 and 3 (forward
direction) and records all tracks. The
heads are mounted on an unusually rigid
die -east and machined block which is securely and accurately mounted to the die
cat and machined main chassis.
In keeping with its professional head
assembly, the 2070 uses tape lifters and
pressure rods (not pressure pads) similar to the ones used on the Ampex 300
(scaled to size of course). Seem to be
made of the same milky -white glass -like
material. The tape guiding system is
appropriately ecctnate.
The Drive System
CIo- examination reveals a highly unusual system for driving the tape past
the heads there are two capstans, one
at each end of the tape head block. This
short, tightly controlled path past the
heads insures precise tension and speed
control. In fact, as the performance data
will reveal later, this machine has the
lowest flutter we have encountered in a
tape recorder designed for this purpose
(professional recorders ntny have lower
:
flutter).
The single- speed, electrically- reversible motor has a three- stepped pulley
Fig.
1.
Ampex Stereo Tape
model 2070.
Recorder,
for
driving the capstans, plus another pulley
for driving the reels. The capstan pulleys
drive a belt which loops about the two
massive flywheels used to drive the cap-
stans. An x -ray view from the top would
show the belt in a roughly triangular
shape, around the motor pulley at the
apex and around a flywheel in each
remaining corner.
The tape reels are also driven by a
belt system, which derives power from a
pulley on the motor shaft. This belt goes
around three idlers, two of them are close
to the tape reels and mounted on an arm
which permits these idlers to contact the
respective reels for fast forward or reverse. Ordinary speed is imparted
through a large diameter wheel below
the reel which is brought into contact
with an appropriate surface on the idler.
The drive system is both simple and
rugged. Our guess would be that it will
hold up extremely well, and with little,
if any, trouble.
We are unable to describe the electronics of this machine because a schematic was not available at the time we
tested it, at least not to us. However, we
can note that it is a tube circuit.
Performance
An interesting facet of the performance specifications given by Ampex is
that they publish two sets average and
guaranteed minimum performance. We
found that all our readings came closer
to the average rather than the minimum
value. With the reputation of Ampex, it
is exactly what we would expect.
The frequency response at 71/2 ips
was within 2 db from 30 cps to 17 kc;
at 33/4 ips within 3 db from 45 cps to 12
ke; at 17/e ips within 3 db from 50 cps
to 5.5 ke. Signal -to -noise ratio at 71/2 ips
was 51 db, at 33/4 ips it was 46 db, and at
17/a ips it was 42 db. Total flutter and
wow at 71/2 ips was 0.07 per cent at 33/4
ips it was 0.14 per cent, and 17/s ips it
was 0.21 per cent. As we noted before,
this flutter reading is excellent. The
speed accuracy at 71/2 ips was within 0.5
per cent, at 33/4 ips it was within 0.8 per
cent, and at 17/g ips it was within 1.9 per
cent.
Power output from the built -in amplifier was 8 watts runs per channel.
The Ampex Model 2070, and its related
brethren in the 2000 series, are obviously
excellent machines at a modest price.
You'll be quite pleased at its ease of
operation as we were, but its best quality
Circle 160
is performance.
:
BARKER & WILLIAMSON
DISTORTION METER AND
VOLTMETER, MODEL 410
Distortion is that quality which a high
fidelity product should have none of.
Of course even the world of high fidelity
is. not perfect so we must settle for the
lowest distortion we can achieve.
The B & W Model 410 distortion meter
is a high quality instrument designed to
tell us the distortion level we have
AUDIO
46
www.americanradiohistory.com
SEPTEMBER, 1964
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SEPTEMBER, 1964
www.americanradiohistory.com
CECIL E. WATTS MANUAL
"HOW TO
CLEAN, MAINTAIN
AND PROTECT
achieved. In addition, it is also a very
fine a.c. VTVM which measures rms
voltage from 0.0001 to 300 volts, independent of frequency from 20 cps up to
200 ke. Of course, the voltmeter also
reads db with a range from - 75 to + 52,
or 127 db.
Adding up its various parts we end up
with an instrument capable of being used
for a variety of audio applications in
addition to the ones mentioned It can be
used to pleasure noise levels of audio
amplifiers; modulation of transmitters;
as an amplifier for low -level a.c. signals
(a 1. my signal can be amplified 200
times) ; single- frequency filter from 20
cps to 20,000 cps; a null indicator; and
so on. Most important, it performs all
these functions with accuracy and reliability.
:
RECORDS"
This new author-
HOW TO
itative guide
CLEAN, MAINTAIN
written by Cecil
E. Watts, noted
record care expert shows you
professional procedures on handling, care and
maintenance of
records.
AND PROTECT
RECORDS
r,
Nani.e
by
MerMdce
MIL Z.
Mernlenece
WATTS
In.
ro.ecyn
.o
nre erunrernor.ry
MRecognized
Only 25¢
Do you know how to reduce surface noise?
How to eliminate static? How to properly
store your records? Did you know that
more records are discarded because of
damage in handling than because of ordinary wear? You can avoid the pitfalls and
protect your investment by following the
instructions in this new manual the most
complete guide to the care and treatment
of records ever written.
-
No Other Manual Like
It!
This guide belongs in every record owner's
library for continuing reference. It contains such valuable chapters as:
How to handle records
The miracle in the groove
Dust and Static
When to apply anti static agents
Storage of records
Cleaning equipment
Rejuvenation of records
Learn how to get all
record collection can
to restore old records
Learn how to give all
lease on life. Start to
the enjoyment your
deliver. Learn how
to useful life again.
your records a new
protect your record
collection immediately for only 25c, a fraction of the cost of one record. Send for
your copy today.
Elpa Marketing Industries, Inc.
New Hyde Park, N. Y.
1
Dept. A -9
am enclosing 25c. Please send me my copy of
E. Watts Manual, "How to Clean,Malntain and Protect Records."
I
Cecil
Name
Address
City.State
kw mg, me
Ens ow now
m.
CIRCLE 125
48
-J
Fig. 3. Barker & Williamson
Distortion
Meter and Voltmeter, Model 410.
The rms value of the signal used as
100 per cent reference is approximately
1 volt,
Distortion Meter Circuit
The Model 410 has a highly- selective
Wien bridge to "notch" out the fundamental frequency of the test signal, a
sensitive a.c. amplifier to amplify the
harmonics, and a meter circuit to read
percentage distortion. Here's how it
works (see Fig. 2) :
The signal is first applied across the
R
pot,
through C. R, attenuates the signal to approximately 100
my before it is applied to the first amplifier tube VIA, where it is amplified 10
times and applied to the grid of the
phase inverter tube, V2, through coupling
capacitor C1. This amplification is necessary to provide sufficient signal level to
overcome any hum or noise that might be
present in the nulling circuit. With
RANGE switch S20 in CALIBRATE position,
and FUNCTION switch Si in one of the
distortion frequency positions, V2 operates as a cathode follower rather than a
phase inverter. Now the signal through
V2 goes to feedback amplifier tube V,B
and on to a reference point between resistors R5 and Re. At this point the signal represents a gain of 1 compared to
the signal at the grid of V2, which means
that if the fundamental frequency is
eliminated between V2 and V,B, the signal at the reference point will consist of
the harmonics only, and the amplitude of
the harmonics will be the same as at the
gird of V. The tunable Wien bridge
"notch" is brought into the circuit when
RANGE switch S2 is set at a "% distortion"
position. The frequency range of the
bridge circuit is determined by C,
through C12 which are selected by FUNCTION switch, S1. The normal response
curve of a Wien bridge circuit is much
broader than required for this application so that a large amount of negative
feedback is applied from the plate of
VIB to the grid of V. This provides a
sharp notch at the fundamental freCALIBRATE
quency.
and the voltmeter sensitivity at
100 per cent distortion position is 100
Inv, so that it is necessary to attenuate
the signal to about 0.1 of its normal value
by means of Rs and R, before it enters
the meter circuit.
Voltmeter Circuit
The input signal is applied across an
attenuator, R21 and RE2, when the function switch is in VOLTS position. Attenuation is 1000 times to prevent signal level
exceeding 300 my at the grid of cathode
follower V;A. The gain at this tube is approximately 0.95. The signal then goes to
the junction of R24 and R5Si and from
there through coupling capacitor C29 to
the attenuator, .R 5 through
RANGE
switch Sea is adjusted so that the rms
value at the grid of VB, the first voltage
amplifier, does not exceed 1 mv, the value
which produces full scale deflection of
the meter. The signal is then subjected
to a net gain of 55 db by the time it
reaches the junction of R42 and R44 in
the cathode of V4B. The signal then goes
to the rectifier -bridge circuit consisting
of C22, C23i CR and CR2. A pulsating
d.c. is applied to the milliammeter. At
the same time a.c., from the output of
the bridge, is applied as feedback to the
cathode of V34 through Rá5 and
R46
is adjustable to vary the gain of the amplifier. The a.c. output of the bridge
circuit is also available at the output
jacks.
The power supply consists of a 6X4
rectifier tube, sizable filter capacitors,
and an 0A2 voltage regulator tube to
stabilize d.c. to the voltmeter circuit so
that it is unaffected by line variations.
R.
R.
Statistics
The B&W Model 410 measures harmonic distortion of signals with a fundamental in the range 20 cps to 20,000 cps.
It is accurate within 5 per cent of full
scale deflection with residual frequencies
up to 60,000 cps (0.05 per cent on the
AUDIO
SEPTEMBER, 1964
lowest scale), and it is accurate within
15 per cent of full scale with residual
frequencies between 60,000 and 100,000
cps. In comparison with other instruments known to be equally accurate, the
B & W Model 410 gave precisely the
same distortion readings. Input impedance for distortion measurements is
100k ohms shunted by 82 pf, and the
input sensitivity is 0.1 to 30 volts rms.
The voltmeter is accurate within 5 per
cent of full scale from 20 cps to 200,000
cps. We found that this VTVM compares
exceedingly well with instruments of laboratory quality. Voltmeter sensitivity is
0.001 to 300 volts rms for full scale deflection. The input impedance is 1 megohm shunted by 27 pf in the 300 -1 volt
position, and 1 megohm shunted by 39 pf
in the 300 -1 mv position. The voltmeter
residual noise is less than 0.02 mv. The
output terminal voltage is 0.2 volts rms
for full scale reading on any range position.
In sum, the B & W Model 410 is a
high quality distortion meter, and an
equally fine a.c. VTVM. It is definitely
several cuts above the service instrument
classification. Its price category is in the
under $200 range. A good buy for its
Circle 161
category.
do you have a monkey wrench
in your automatic turntable?
Any spindle that permits the stacking of records on a
turntable throws a monkey wrench into the entire system.
REGULATED POWER SUPPLY
Any experimental or developmental
work with electronic gear has always required some source of voltage-usually
d.c., and sometimes with a.c. being required in addition for heater supply with
vacuum-tube circuits. When one begins to
experiment with transistor circuits, d.c.
is still required, generally at lower voltages and higher currents. With power
amplifier circuits, storage batteries seem
a logical source of d.c., but this type of
battery has a very low internal resistance
and in the event of a short, the current
can increase tremendously. Attempted
protection by means of fuses does little
good because they are not fast enough
the transistor goes before the fuse does.
Obviously, the answer lies in a currentlimited, voltage -regulated power supply
operating from the usual 117 -volt a.c.
-
-
tion
(Continued on page 58)
AUDIO
-
Here is a precision 4 -speed transcription turntable with an integrated Thorens tone arm (BTD-12S), for
those who prefer a complete, compact unit. Exceeds NAB
standards for rumble, wow and flutter. Features 12 -inch
non -magnetic table, variable speed control, precision mounting. Tone arm has amazingly low tracking error, and is
designed for lowest possible inertia and friction. No other
integrated unit approaches the professional standards and
Net $99.75
economy of the TD -135.
TD -135
-
If you want highest performance plus convenience, see the amazing Thorens TD -224. There is no
other instrument like it in the world. Combines the playback quality of a transcription turntable with the convenience of an automatic record changer. There is never a
record stack on the turntable, yet records change automatically. Overcomes all problems of "automatics.' TD -224
incorporates the BTD -12S professional tone arm, plus a
built-in record cleaner, ilium nated strobe, variable speed
control. A superb instrument with features never before
Net $250
combined in a single instrument.
TD -224
IP-20
Transistorized Regulated Power Supply,
shown in Fig. 4. This unit provides any
voltage from 0.5 to 50 at any current
from 0 to 1.5 amperes with a regulation
of ± 15 millivolts maximum (it can be
adjusted for zero regulation at any selected voltage). In addition, it has an
automatic current limiter to protect both
the load and the power supply itself, together with an overload relay which
opens in case of a direct short or overload. The circuit employs five transistors,
nine diodes, one Zener diode, and a voltage-regulator tube for the reference
-
Recognized as the finest performing transcriipturntable, the Thorens TD -124 features 4 speeds,
built -in illuminated strobe, flawless sound. Unmatched
Net $125
for mono or stereo reproduction.
If you demand top quality yet need only a
TD -121
to any
Converts
TD
-121.
Thorens
the
single speed, see
standard speed you select. Flawless performance, as in
Net
Thorens
equipment.
$85
all
TD -124
-
line.
Such a device is the Heathkit
-
The stacking of records varies the stylus angle increases
the load on the motor creates flutter and wow -wears
records diminishes your listening pleasure. IS IT WORTH
ALL THAT JUST TO CHANGE RECORDS?
HEATHKIT MODEL IP -20
THOREN5
A
sound ]UFereation * Product
If your dealer can not qualify for a Thorens Franchise -go to another one!
ELPA MARKETING INDUSTRIES, INC., Dept. A -9, New Hyde Park, New York.
*
sound J
crleation
-
A Mark of Elpa Marketing Industries, Inc. In
/
Canada:
Trl -Tel Associates, Ltd., Willowdale, Ont.
Circle 126 on Reader Service Card
49
SEPTEMBER, 1964
www.americanradiohistory.com
16th ANNUAL
CONVENTION AND EXHIBITS
OF THE
AUDIO
ENGINEERING
SOCIETY
Showing Professional Audio Equipment for Studio
and Laboratory
IITRI STORY
(from page 2.c)
to
33/4 ips or, hopefully, to Ws ips. Most
recorder manufacturers, prerecorded
tape companies and raw tape producers
are enthusiastic about the project because, even though it will mean that a
hobbyist needs only a quarter or half as
much tape to record a symphony, slow
tape speeds will reduce the cost of recording to a point where the industry
can compete successfully with records.
An offshoot of Caniraas' work on recording at slower tape speeds is the
IITRI tape cartridge system, introduced
in 1959, at approximately the same time
as CBS Laboratories introduced the system which is being used by Minnesota
Mining & Manufacturing. The IITRI
cartridge can be changed automatically
by a player changer. It can also be
played on a conventional recorder because it uses standard quarter -inch recording tape. It can be recorded stereophonically in both directions (as reel -toreel tape is) and can be recorded at any
standard tape speed. Sonic IITRI staffers hold out for 3 3 ills as the optimum
speed for the system, because it combines
fidelity with a long playing time. Caniras
says that it could work just as well at
7' . ips with half the playing time, or at
17 s ips. "It's very economical for a tape
duplicator to produce cartridges, even if
there are no machines to play hack automatically. Cartridges can he played on
ordinary machines until the public owns
enough of them to demand the introduction of an automatic player." He notes
that at 33/4 ips, the cartridges could contain as much as 11/2 hours of music.
"This smaller size is much less wasteful
than the big boxes tape conies in now.
When I look at the small amount of tape
that conies on some of those scven -inch
reels, I'm shocked."
The Caniras cartridge system contrasts
with the Minnesotan Mining cartridge
player, introduced last year to the public.
The latter uses wallet-sized cartridges
which c'nntain a maximum of 4S minutes
of music and, because of the width of the
tape they use, are nut compatible with
existing recorders. The 3M tapes are
recorded in one direction only and must
be rewound before the changing mechanism drops the next tape. The Camras
cartridge eau be recorded in both directions, as is a eimveutioual prerecorded
tape. This permits the inclusion of twice
as much music in the same size cartridge
and the reduction of the interruption between one cartridge and the next.
Is IITRI prepared to do battle with
uianufnttarr19rs over a cartridge player
systew ! "We're not in the business of
manufacturing or marketing magnetic
recording products," Dr. Brophy explains. "We believe we have a pretty
1
OCTOBER 12 THROUGH 16
AT THE HOTEL BARBIZON- PLAZA, CENTRAL PARK SOUTH,
NEW YORK CITY, NEW YORK
IMPORTANT PAPERS ON: Microphones and Earphones Architectural Acoustics Sound Reinforcement Disc Recording
and Reproduction
Magnetic Recording and Reproduction
Consoles and Controls
Music and Electronics
Audio and
Man
Audio Amplification
Solid -State FM Stereo
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Audio at the New York World's Fair
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SESSIONS Monday through Friday, 9:30 a.m., 1:30 and 7:30 p.m. Annual
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Program available -phone 12121 -MO
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AUDIO ENGINEERING SOCIETY
Post Office Box 383, Madison Square Station,
New York, New York 10010
50
-
AUDIO
SEPTEMBER, 1964
good cartridge player system, and we're
showing it to people who might like to
manufacture and market it wider license.
I might say that some manufacturers
have expressed interest in it." He said,
too, that the manufacturers in question
were waiting to see what would become
of the other cartridge systems before
making their own moves.
Home Video Recorder
Certainly one of the most interesting
pieces of equipment on the premises at
IITRI is Camras' working model of a
home videotape recorder. "I'm actually
working on several approaches," Camras
says when discussing the subject of
videotape. "The picture quality of cheap
machines now is substandard. What I'm
trying to do is to produce a machine
which can produce a picture quality
which will be acceptable in the home at
a price acceptable to the general public."
As a result, Camras actually has two
types of recorders in mind one which
will operate at 120 ips using standard
audio tape on a seven -inch reel ; and one
which will use half -inch tape at a speed
of 71/2 ips. The fast speed is being used
by Cinerama- Telcan and Fairchild Camera Corporation, the first two companies
to demonstrate low -cost home videotape
recorders. The IITRI 120 -ips machine
will record an hour of picture and sound
on a seven -inch reel of triple play tape
by making ten passes across the tape. A
:
ABC -AM & TV
TORIES
reverse -o -matie feature reverses tape direction automatically at the end of each
track with a brief interruption. Fairchild
uses the same feature on its machine,
which makes four passes on an 11 -inch
reel of triple play instrumentation tape
and also yields an hour's recording time.
The Telcan recorder gets 22 minutes on
each of two tracks on an 111/4 -in. reel of
standard audio tape. The 71/2 -ips recorder uses a half-inch tape coated with
an audio oxide formulation and produces
a picture quality similar to 16-mm black
and white movie film. "In the meantime,
I'd expect to see several home recorders
at a lower price offering low- quality
videotape as an extra feature. The buyer
would realize that the picture quality is
poor, but he'd be getting the video feature, in effect, for free when he buys a
conventional sound recorder."
IITRI's work on a tape speech compressor may not be of immediate interest
to hone recordists, but it could have profound implications in broadcasting and
business. "When a stenographer slows
down or speeds up a tape now on which
a letter has hcen dictated," Camras explains, "there is a consequent lowering
or raising of the pitch of the voice. If
you cut the speed in half, as you would
playing back a tape recorded at 71/2 ips,
at 33/4 ips, for example, you hear it an
octave lower than it was recorded. It's
almost unrecognizeable. What the speech
CBC- CANADA
CBS -AM & TV
Æ
BASIN STREET EAST
AMERICAN LUTHERAN CHURCH
CADENCE RECORDS
compressor will do is to allow you to slow
down or speed up a recorded voice without any change in its pitch. A secretary
would be able, by adjusting a knob, to
play back a tape at any speed she chooses
and still hear her boss speaking in his
normal voice. This has applications in
broadcasting. Suppose, for example, you
have a recorded speech which runs 32
minutes and you've got only 30 minutes
in which to broadcast it. You'll be able to
play the whole tape -without editing,
and without any unnatural sound in the
voice -in the half hour."
The IITRI researcher said the compressor hasn't been fully developed, and
declined to discuss details of the invention. But raw tape manufacturers already are rubbing their hands in glee at
the prospect of wholesale conversions of
offices to tape and recorders for dictation, which such an invention would
cause.
What does the man who does the work
in the back room of the tape industry
see coming next in magnetic recording?
With Camras' typical humor, he notes,
"Looking hack at periods just prior to
the announcement of major advances in
magnetic recording of .the past, I notice
that there are no definite foreshadowings
of what would take hold next. Therefore
my best advice is not to put too much
faith in any predictions of mine. We
will continue to expect the unexpected."
BELL TELEPHONE LABORA-
CATHEDRAL OF ST. JOHN THE DIVINE
HITSVILLE,
COLUMBIA RECORDS
CLEVELAND RECORDING CO.
CAPITOL RECORDS
NBC-AM & TV
THE MORMON CHURCH
MGM PICTURES
LIBRARY OF CONGRESS
RIVERSIDE
RECORDING
RCA VICTOR
NICOLET HIGH SCHOOL
PRATT & WHITNEY AIRCRAFT
THUNDERBIRD HOTEL THE UNITED NATIONS UNITED RECORDING
CHURCH
"'
UNIVERSITY
UNIVERSITY OF GEORGIA
SERVICE
BAND
WARNER
CORPS
U.S.
MARINE
OF MICHIGAN
WINS
BROS. PICTURES
WBTV THE WHITE HOUSE
U.S.A.
WKIX
WTTG (NBC)
... and
many hundreds more!
PROOF?
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Circle 130 on Reader Service Card
AUDIO
OTH
Adm.
M
AUDIO CORPORATION
212 -00 -5 -4111
2 WEST 46 STREET, NEW YORK, N.Y., 10036
In Canada: 1 -Mar Electronics Ltd., P.O. Box 158, Don Mills, Ontario
51
SEPTEMBER, 1964
www.americanradiohistory.com
NEW PRODUCTS
Column Speaker System. The En] pi r.
Grenadier Model S000 is a column- shaped
speaker system with a divergent lens for
the mid and high frequencies. Not only is
it a handsome piece of furniture, but also,
it permits placement in almost any convenient place in the room. Frequency range
is 30 to 20,000 cps, power handling capacity, music power, is 100 watts, and nominal
impedance is 8 ohms. It contains a 12 -in.
woofer with 4 -in. voice coil, a direct radiator mid range, and a dome tweeter. Its
dimensions are 29" high, 15 %" in diameter
and it weighs 65 lb. It is finished in satin
walnut polyester. Price is $180. Empire
Scientific.
Circle 196
Stereo Taps Recorder. Concord Electronics has released the Concord Model
440 which allows up to 24 hours of recording time on a single 36001 reel of tape,
at a playing speed of 1% ips. In addition
the Concord 440 features pushbutton operation, transistorized preamps, three
speeds, sound -with -sound, exclusive Concord Trans -A- Track, separate mixing inputs, automatic pressure roller disengage-
all response of the system is 53 cps to
17,000 cps ± 21/2 db. The Newport handles
45 -watts of program material. Minimum
drive requirement is 10- watts. The speakers are mounted on a one -inch thick resinlilted flakeboard baffle. The enclosure itself
is made of three -quarter -inch solid -core
walnut veneered plywood. Size of the enclosure is 24 x 13 x 914- inches deep. Called
automatic relay switching to proper mode
and automatically indicates FM- stereo
multiplex or monophonic. The unit is
priced at $169.95. Kenwood Electronics
simultaneously announced a new high power integrated stereo amplifier, Model
KW -220, total 100 watts music power.
Thirteen front -panel controls provide for
every possible use. The KW -220 is also
priced at $169.95. Kenwood Electronics,
Inc., 3700 South Broadway Place, Los
Angeles, California. 90007.
Circle 190
Microphone Mixer Amplifier. A new four channel all- transistor microphone mixeramplifier has been added to the Public
Address equipment line by Bell Sound.
Designated the Be -M4, the new mixer is
designed to work with any existing PA
amplifier or booster amplifier to extend the
input capability of the system. The Be -M4
includes individual inputs and gain controls for four low -impedance microphones
and an external phono unit. A VU meter
is included as well as headphone jacks so
program level may be monitored both
aurally and visually. A new feature is a
cueing facility on each microphone channel. Vc h 1fl r,.phone gain control can be
the Model Sß1, the Newport has .. hand rubbed walnut finish and cane grille. Either consolette legs or pedestal bases are
available. The enclosure is also available
in unfinished birch. Sherwood Electronic
Laboratories, Inc., 4300 North California
Ave., Chicago, Ill.
Circle 200
Theatre Organ Kit. A three -manual
"Theatre" organ kit, the "Cinema," smallest and latest of the Artisan family, measures only 30" deep and 46" high, yet
meets AGO specifications with three full
61 -note manuals, a concave, 32 -note clavier.
Other features include iutermanual couplers, twin expression pedals, independent
vibratos, independent oscillators for every
key of each keyboard, built -in music light
pulled into the "cue" position and the VU
meter may be switched to that microphone
position, permitting the operator to adjust
microphone levels and preview the sound,
prior to switching it to the program line.
The Be -M4 has a response of 20 to 20,000
cps ± 2 db and requires 5 watts of a.c.
power for operation. Its size of 3" x 10" x
15" and styling are compatible with other
Bell Be- series amplifiers. It weighs 9
pounds. Regular unbalanced 600 -ohm output (or balanced 600 -ohm output by using
a plug -in output transformer) is provided.
A special control output permits it to control standby power on a remote booster
amplifier, if desired. TRW Columbus Division, 6325 Huntley Road, Columbus 24,
Ohio.
Circle 199
ment, two dynamic mikes, cue and edit
button, and a digital tape counter. The 6"
wide -range speakers are separated, with
additional speaker outputs available. The
Concord 440 is priced at $240. Concord
Electronics Corp., 809 North Cahuenga
Blvd., Los Angeles IS, Calif.
Circle 197
Multiplex Tuner. Kenwood Electronics,
Inc. has introduced a new automatic stereo
multiplex tuner, Model KW -500 featuring
an exclusive FM- stereo indicator. The all new KW -550 front panel design incorporates a red light which automatically
changes to blue when receiving FM stereo
stations. The new Kenwood model features
Speaker System. The Newport, a two way speaker system has been added to the
line of three -way systems made by Sherwood Electronic Laboratories. Priced at
$84.50, the system features a ten -inch
woofer, a four -inch midtweeter, and an
1,800 -cps crossover network. A high compliance device, the ten -inch woofer features a single roll suspension which provides a 23 -cps free -air resonance for
extended low- frequency response. In addition, the woofer voice coil has a four layer
winding which boosts efficiency, and has a
one -inch -long throw to minimize distortion. A special combination midrange and
tweeter speaker, with a shallow -ring radiator, reproduces the mid -frequencies as
well as the super -high frequencies. Over-
52
and pre -set combination pistons. The console style, modified for the home, is influenced by the romantic organ of the
silent movie era and offers a stop list of
authentic theatre voices. Chimes, orchestra
bells, vibra harp and bandbox are optional.
A variety of finishes and matching tone
cabinets is available. Artisan Organs, 2476
N. Lake Ave., Altadena, California.
Circle 201
Stereo VII Balance Meter. Lafayette
Radio Electronics Corporation introduces
an audio output level indicator for maintaining proper balance of stereo systems.
It is Model TM -45. Price, $7.95. Two precisely- damped loudness meters have continuously variable attenuators for up to
AUDIO
www.americanradiohistory.com
SEPTEMBER, 1964
9e6
...THE EXCITEMENT IS ABOUT TO BEGIN
Now she says ... "Turn it up, please"
She gets pleasure from the sound of the McIntosh
MA 230 control amplifier. She wants to hear all the full
rich sound. She even thinks the loudspeakers sound
bigger. Her bridge club wants to listen. Sometimes you
wish she would let you listen to what you want to hear.
The McIntosh MA 230 control amplifier brings
exciting performance to your present stereo system. The
amplifier is the heart of your music system. All sound
sources must go in and come out of the amplifier. Why
deny her full enjoyment from your stereo system with
an inadequate amplifier? Let her hear stereo through an
MA 230. She will exclaim at the exciting difference she
hears when using the McIntosh MA 230.
SPEAKERS SOUND BIGGER
Your speakers will sound bigger. Hum, noise and
distortion from inadequate amplifiers color the musical
content of the program material. Your speakers reproduce all of this. Distortion makes the music harsh and
hard to listen to for long periods of time. Hum robs
your loudspeakers of bass response. The McIntosh
MA 230 has the lowest hum and noise of any control
amplifier. Total hum and noise is 1/1,000,000 of the
total power output. The MA 230 has less distortion
than any other control amplifier with both channels
operating. Distortion at a full thirty watts per channel
is less than jí of 1% from 20 cycles to 20,000 cycles per
second. IHF music power rating is 44 watts per channel.
Power to spare! No other control amplifier gives this
kind of performance.
Your records will expand and have a transparent
quality. The solid state preamplifier of the MA 230 has
the best dynamic range of any control amplifier.
Dynamic range makes music come alive. From the
fflt tnt ash
LABORATORY INC.
6 Chambers St., Binghamton, N.Y.
Circle 131 on Reade
AUDIO
softest to the loudest passage the McIntosh MA 230
delivers all the program material. Each note, each passage comes alive.
'AMERICAN RECORD GUIDE' REPORTS
ON THE MA 230
"McIntosh is an exception. It is one of the few firms in
the industry that has a reputation for consistent understatement. Its eminence in the amplifier- preamplifier-
tuner field is built on a secure foundation of performance -and on specifications written in the engineering, not the advertising, department."
"I did a lot of listening with this unit. It is powerful,
and it is honest, in its presentation of music. I am
bound to say that the MA 230 stands with the very
best units I know of any design. I invested considerable
time and effort in trying to disprove McIntosh advertised specs. I could not do so. I do not know another
integrated amplifier with such superb power response."
FREE THREE YEAR FACTORY SERVICE
You get a full three year factory service contract on all
parts and labor. Only tubes, fuses, and transportation
are excepted.
EASY TO OWN
Now most dealers offer the McIntosh MA 230 for only
$35.00 down and as little as $12.00 per month. Your
old amplifier can more than likely cover the down
payment.
McINTOSH LABORATORY INC.
6 Chambers St., Binghamton, N. Y.
Send today for the full American Record Guide test
report, plus the full story on the McIntosh MA 230.
Name
Street
City
Zone
State
Service Card
SEPTEMBER, 1964
53
www.americanradiohistory.com
New Tuner -Amplifier. A new 80 -watt FM
stereo tuner /amplifier with brushed silver satin styling has been introduced by Sherwood Electronics Laboratories, Inc., Chicago. The new component, called the S8000IV, features a powered center speaker
attenuation of each channel. A calibration switch permits exact matching.
Scales are calibrated in VU and percent.
Input impedance is greater than 8000 ohms
per channel, and sensitivity 1.2 volts. The
meters respond to speech or music waveforms and are ideal for stereo speaker
20 -db
level matching or maintaining equal outputs from a stereo tuner. The entire unit
is housed in a plastic case 6 "W x 31/.r "H x
27/8"D. Predrilled for panel mounting.
Shpg. wt., 3 lbs. Lafayette Radio Electronics, 111 Jericho Turnpike, Syosset,
N. Y.
Circle 205
channel. The new integral channel permits direct connection of a center or third channel speaker system, or the addition of
extension monophonic speakers in other
rooms. No extraneous wiring or patching
is needed and no external power source is
required. In addition, the S- 80001V has a
front -panel stereo headphone jack and a
front -panel speaker disabling switch which
gives the listener complete control over
his listening options. The tuner -amplifier
has a 1.8µv UHF) sensitivity for receiving
low -power FM stations. A 2.4 -db capture
effect eliminates stereo broadcast background noise and a special interchannel
muting circuit suppresses between -station
noise when tuning. FM distortion is only
0.3 per cent at 100 per cent modulation.
Price of the new component is $329.50. A
leatherette case is available at $9.50, and
a genuine walnut cabinet is optional at
$29.50. Sherwood Electronics Laboratories,
Inc. 4300 N. California Ave., Chicago, Ill.
Circle 202
60618.
Speaker System. Lafayette Radio Electronics Corporation has added a new
speaker system, the Decor-ette Ill, a threeway bookshelf speaker system. Called the
SK -275, the system employs three custom
made British speakers. The speakers feature a newly -developed 12 -inch woofer
with a special foam -treated cone and a
free-air resonance of 35 cps, a 6 -inch midrange unit with closed back to prevent
interaction with the woofer, and a sealed
cone -type tweeter. Using a sealed enclosure with a tuned -tube duct, the system
achieves an over -all response from 30 to
30,000 cps. The crossover points are at 2,000 and 5,000 cps. Although maximum
power rating is 25 watts continuous or 50
watts instantaneous peak, the system may
be used with amplifiers rated as low as
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10 watts. Impedance is nominal 8 ohms.
Available in oiled walnut. May be placed
either vertically or horizontally. The system measures 14" x 24" x 12" deep and
weighs 30 lbs. Price: $79.95. Lafayette Radio Electronics Corporation, 111 Jericho
Circle 203
Turnpike, Syosset, N. Y.
"Football- Shaped" Speakers. Roughly
equivalent to corresponding oval speakers, the new "football- shaped" speakers
use only two mounting studs instead of
four. The 5 x 8" model, SP58D -8, has a
1.47 ounce Alnico V magnet; the 6 x 10"
model, SP610E -8, has a 2.15 ounce Alnico
V magnet. Both speakers employ 8 -ohm
The Model 688 is available with or without transformer input, and a 70V
line transformer output is available as an option. Gain 83 db. Sensitivity
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RECORDING EQUIPMENT CORPORATION
1040 45th Ave., Long Island City I,
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voice coils. The SP58D-8 has the same
size cone and pad ring as a conventional
is one
5 x 7" speaker, but the "basket"
inch longer. The model SP610E -8 is similarly equivalent to a 6 x 9" speaker. Utah
Electronics Corp., 1124 E. Franklin St.,
Circle 204
Huntington, Ind.
Circle 127 cn Reader Service Card
54
AUDIO
SEPTEMBER, 1964
AUDIOCLINIC
(frnm Fuge
1)
Oscillation in Amplifiers
Q. My home -built amid' tier worked
fine until two months ago. The circuit
is an ultra -linear Williamson, using
6SN7's as phase splitter and drivers.
The output tubes are 807's feeding a
Stancer output transformer. The trouble
with the amplifier is oscillations front
about 500 cps on, drown,. The oscillations
shone up as riders on a. sinew are.
resistors and capacitors are within their
rated tolerances. The capacitors are not
shorted or leaking. In fact, the coupling
capacitors are oil -filled units. The voltages are correct as specified on the
schematic.
By open- circuiting the feedback loop,
or reducing it to thr ])oint inhere there
is almost no feedback. I croc make the
oscillations disappear. I tried )hanging
the rabic of the phi..'- ..hiftnng capacitor
acro..., the feedback resistor. Increasing
its value to about four times normal
helped somewhat. As far as I can tell
nrith an ohmmeter, the output transformer is all tight.
I hare a number of books on amplifier
repair. I tried all the suggestions they
had to make, to no avail. William A.
Sasek, San Leandro, California.
A. I have a suspicion that the output
transformer is defective, possibly suffering from a shorted turn somewhere along
the line. A noticeable decrease in power
output would support my theory. Severe
oscillation can also reduce the power output of an amplifier, but your description
does not seen to indicate that the oscillations are that severe.
Are you quite certain that the decoupling and filter capacitors are still holding their values ? If not, oscillations can
result.
A shorted turn in a power output
transformer does not change the dc resistance of the winding to any great
extent, therefore the ohmmeter test
would not he conclusive.
The FM Band and TV Receivers
Q. In adjusting the strips of the turret
tuner of mg Tr set, I hare found that
the Channel 6 strip can be toned to certain FM stations though perhaps with
more distortuot than with an FM tuner.
If clone properly, can one get good
FM reception by this method? Can
strips be altered so that they can cover
the conosnlete FM baud (mine covered
only a small part of it) or does anyone
make such strips? Wm. f. Tally, Gadsden, Alabama.
A. You probably cannot obtain good
FM reception by tuning the slugs of your
TV tuner if the set you have is of mod-
AUDIO
However, this tuner does not have good
sensitivity. It, too, might have to be replaced by a turret tuner.
I know of no strips which are made
specifically to cover the FM band. However, the Channel 6 strip can be altered
by removing some turns so that the frequency of oscillation will be raised,
thereby allowing the strip to be tuned
over the entire FM band. You will have
to remove both rf and oscillator turns.
If the coils are tapped, you will have to
remove turns in such a way as to keep
the tap at the saute relative position on
the coil. The rf must he made to resonate
to the middle of the FM band.
ern design because the detector of this
receiver is designed to accept a bandwidth narrower than that used in the FM
band.
Sonic television receivers can be used
in the manner you specify here because
of their greater bandwidth. However,
they are not of the intercarrier type and
are usually old models. Two television receivers which can give adequate FM performance are the RCA 630 and the Dumont RE -10l. In the case of the RCA,
the tuner would have to be replaced with
a turret tuner. The Dumont receiver has
a tuner which covers the entire spectrum
of TV channels, plus the FM band.
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FAIRCHILD INTEGRA COMPONENTS are to
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compact compressor
COLUMBIA BROADCASTING SYSTEM
NATIONAL BROADCASTING CO.
MGM RECCAPITOL RECORDS
'AMERICAN BROADCASTING COMPANY
MERCURY RECORDS
FORD
DECCA
(U.
S.)
PICTURES
AND
ORDS
ELECTRICAL MUSIC INDUSTRIES LTD. (EMI)
MOTOR COMPANY
U. S. INFORMATION AGENCY -VOICE OF AMERICA
WARNER BROTHERS
WBNS
WCBS
DISCOS MEXICANOS
DEUTSCHE GRAMAPHON
KPOL
KMLA
KMLX
WEFM
WIP
KDKA
WNEW
WTTG
WSM
U. S. ARMY /AIR FORCE MOTION PICTURE
WPAT
WBZ
CKBL
GOTHAM RECORDING
UNITED NATIONS
DECCA (England)
SERVICE
PHILLIPS ORGANIZATION
RECORDAK (Division of Eastman Kodak)
(Netherlands) BELL TELEPHONE LABORATORIES WIP U.S. ARMY PICRADIO RECORDERS (Hollywood)
TORIAL SERVICE UNITED RECORDERS
BANKERS
NEW YORK WORLD'S FAIR
EMPIRE BROADCASTING CORP.
WHDH
DOT
TRUST NEW YORK
CONSOLIDATED EDISON NEW YORK
RECORDS
FAIRCHILD Products
REEVES SOUND STUDIOS
GENERAL MOTORS
FAIRCHILD
-
miniaturized overload protection system.
MODEL 664
program equalizer
MODEL 668 LUMITEN
noisefree audio attenuator.
MODEL 688 TRANSISTORIZED
POWER AMPLIFIER
exclusive
protection
with
TRANS /GARD
system.
MODEL 673 DYNALIZER
an automatic spectrum
equalizer. Changes response to complement
human hearing curves.
Write to FAIRCHILD
for complete details.
RECORDING EQUIPMENT CORPORATION
1040 45th Ave., Long Island City
1.
N. Y.
CIRCLE 128
55
SEPTEMBER, 1964
www.americanradiohistory.com
If you are an experimenter, try this
Obtain an old RCA 630 chassis in working condition, insofar as sound is concerned, substitute a turret tuner for the
original unit used in the set. This combination will provide good bandwidth
and sensitivity to make your experiment
worthwhile.
Be certain that you resonate the output of the tuner to the i.f. of the TV set.
Be sure, initially, that the tuner you
select is designed for output on 21 mc,
the i.f. of the 630. If you have a tuner
designed for a higher i.f., you can alter
the tuner merely by replacing the output transformer with one which will
tune to 21 mc. In this work and in the
work of rewinding the Channel 6 slug
you will find a grid dip oscillator to be
an invaluable tool. Such an instrument
enables the user to determine the frequency at which a tuned circuit is resonant.
I shall assume now that you are not
planning to use this receiver to cover
the television channels. What you should
do is to fit the Channel 6 slug with a
coupling which will enable you to adjust
the oscillator frequency externally. The
fine tuning control will not give you
sufficient frequency change, and hence,
the external fitting, directly connected
to the slug.
Naturally, when this slug coupler has
:
been fitted, it will be impossible to change
channels. This is why I had to make the
assumption that you would not use your
receiver for television reception. If you
do wish to use your receiver for viewing,
then you will have to provide a means
whereby the coupling can be easily removed and re-attached when necessary.
If you only wish to hear a few stations, you can obtain several Channel 6
strips and adjust each to receive a particular station. Insert these into the turret
in the spaces where no local television
channels are available. For example, if
there is no channel 3 in your area, channel three can be removed and one of these
altered slugs can be inserted and adjusted to receive a particular station.
This can be done with as many channels
as can be accommodated in the turret.
I am sure that there are other sets
which can be used, but I have not experimented with them. Some of you may
come upon such receivers. If you have
some experience with such equipment,
perhaps you would like to send them to
me for inclusion in my other column,
"Audio Techniques" which appears sporadically in these pages.
High Fidelity AM Reception
Q. In my area there are several AM
radio stations broadcasting an FM format. I would like to listen to them, but
there is one problem, however. These
transmitters are low -power jobs, 5001000 watts. They are sandwiched in between several 50 KW monsters.
I have tried several of the so- called
high fidelity AM tuners with absolutely
no success. They are noisy and nonselective for these low -power stations. I beat
the "selectivity rap" with a home-brewed
r. f. setup with individually tunable
stages. It was not good enough for a decent signal -to -noise ratio.
I would appreciate your specific recommendation as to a broadcast band, AM
only, superheterodyne unit that will give
me reasonably good selectivity, sensitivity and the fidelity that I want. I can get
the first two with a communications reciever but this type of circuit takes no
pains with fidelity beyond that required
for receiving voice frequencies. Besides,
I would be paying for features that I
do not need.
What would you say to a configuration
using several stages of low -noise triodes
in a t. r. f. circuit to obtain adequate r. f.
gain, followed by a superheterodyne circuit? I realize the exhausting tuning involved but I am interested only in receiving two frequencies. Thomas F.
Steiger, Mt. Prospect, Illinois.
A. If an AM tuner is to be reasonably
close in sound to that of a good FM
tuner, it cannot be selective. Selectivity
will cut down on the reception of the
entire sideband envelope. The parts of
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CIRCLE 133
56
AUDIO
SEPTEMBER, 196.1
this envelope which are rejected are the
ones containing the high frequencies
which you need badly. Poor selectivity
will intensify atmospherics and will allow the heterodynes between broadcast
stations to be heard clearly.
If I were constructing a receiver to be
reasonably satisfactory, it would have
to be a compromise between maximum
fidelity and endurable background noise.
I would use one or two r. f. stages. They
would be pentodes. I realize that eascode
amplifiers would have less noise, as you
indicate, but the receiver noise is not
the main kind of noise heard on the
broadcast band. The most common type
of noise is produced by atmospheric
static and by noise which is transmitted
along the a.c. supply line. Such noise will
mask the noise produced in a pentode
stage. Cascode r.f. stages find the widest
acceptance and application in the VHF
portion of the spectrum, where manmade and atmospheric noises are less
INSTRUMENTS
for AUDIO
MEASUREMENTS
MODEL 410 DISTORTION METER
audio distortion, noise level and AC
voltages
Also a versatile vacuum tube voltmeter.
Distortion levels as low as .1 % can be measured
on fundamental frequencies from 20 to 20,000 cps,
Measures
indicates harmonics up to 100,000 cps
Distortion
measurements can be made on signal levels of .1
volt to 30 volts rms
The vacuum tube voltmeter
AUDIO
SEPTEMBER, 1964
-60
MODEL 210 AU DIO OSCILLATOR
sine wave signal from 10 cps to
100 kc
Output level within -!-1 db when working
into 600 ohms (reference 5 kc)
Power output,
variable to above 150 mw
Hum and noise,
Provides
a
-10
apparent.
I would not separately tune each stage.
If I were going to have two ri. stages, a
mixer and an oscillator, I would use a
4 -gang tuning capacitor having the appropriate capacitance range. Naturally,
I would try for maximum tracking but I
would not be too concerned with a slight
amount of mistracking because such mistracking will not degrade the selectivity
of the receiver. The r.f. end of a superheterodyne receiver is used to provide
gain and sufficient selectivity to prevent
image responses. The selectivity of a
superheterodyne receiver takes place in
the i.f. amplifier. ( There are certain exceptions to this, but they need not be
discussed here.)
The signal from the mixer would, in
my version of a high fidelity AM tuner,
feed into two i.f. stages. Here we have
two choices. The i.f. of this receiver
could he set at 1750 Ice or 455 kc. In the
first instance, the i.f. transformers would
be lined up for maximum selectivity. I
would not be at all surprised to find that
such an i.f. strip would be too broad for
our purpose. The 455 kc strip seems
more promising. However, the circuits
would not be aligned for maximum selectivity, but would be stagger -tuned to
permit a total bandwidth of 15 kc. Regardless of the i.f. chosen, I would add
a filter which would limit the audio beyond 8.5 kc. This addition is necessary
to eliminate the whistles produced by the
beats of stations on the broadcast band.
Although you are not able to use a
high fidelity AM tuner, I don't believe
you should consider such tuners as poor
or worthless devices. They will work very
well in locations where the signals you
wish to hear are strong enough to overcome some of the difficulties we have
been discussing. I own such a tuner and
it gives a good account of itself, helped
immeasurably by a filter to remove all
frequencies above 8.5 kc.
Æ
provides an accuracy of -±5% over a frequency range
from 20 cps to 200 KC. For noise and db measurements, the instrument is calibrated in 1 db steps
from 0 db to -15 db, the built -in attenuator provides additional ranges from
db to +50 db
in 10 db steps.
at 5 volts output
Distortion is less than .2%
at 5 volts output from 50 to 20,000 cps, slightly
higher at higher output and frequency extremes.
db
These instruments are supplied with many B.C. station installations
for FCC Proof -of Performance tests.
BARKER & WILLIAMSON, Inc.
EPadio Communication
Equipment Circe 1932
BRISTOL. PENNSYLVANIA
STIUwerl 8 -5581
Circle 137 on Reader Service Card
OVERSOO
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Dept. Al -4, P.O. Box 10
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Send me the FREE 1965 Lafayette Catalog 6501
1.
24
Plainfield.
139 W.
2
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1965
LAFAYETTE
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Circle 139 on Reader Service Card
57
CHOSEN BY
RECORDS
AS THE BEST THAT
MONEY CAN BUY
and caption (the price is an approxi-
mation) appeared in the September 1963 POPULAR SCIENCE as part of an article entitled
"The Low -Down on
Hi -Fi
Stereo." It is
Here he is again, the big man at Salzburg in
his day as Mozart was a century -odd later.
Dluffat, too. His name I had at least heard.
This Biber music is really lovely he was
undoubtedly a lot more than just an average
composer. A series of beautifully played
Baroque works for strings, some with organ, Some with harpsichord accompaniment,
rich in content, gentle in expression. ( l'art
of this gentleness comes from the typical
playing of the Viennese group -utterly different from much American "old music" performance.) As for \lulfat, his big five- section
"Tribute in Harmony" of 1682 tries rather
beautifully to reconcile the rival stylings of
the day, the French and Italian.
;
(WITHOUT FRILLS)
This photo
(from page 41)
a
picture
Applications
EQUIPMENT
PROFILE
(front page 49)
voltage. Two 2N2147 transistors, con-
of those high fidelity components which, according to
a
panel of experts, provide the best
sound possible today.
The panel carefully considered return- for-the-
money, but "where there was a more expensive
component that produced
a
detectable improve-
ment in sound, it was chosen."
These components are recognizable to hi -fi en-
thusiasts as the
AR
two-speed turntable, the
Dynakit PAS -2 preamplifier, the Dynakit Stereo
70 dual power amplifier, and the AR -3 loud-
speakers.*
*They have been on demonstration as
a
system for
several years at the AR Music Rooms, on the west
balcony of Grand Central Terminal in New York City,
and at 52 Brattle St., Cambridge, Mass. No sales are
made there; you may ask questions
if you like, but
most people just come and listen.
ACOUSTIC RESEARCH, INC.
24 Thorndike St., Cambridge, Mass. 02141
Please send me literature on Dynakit and AR high
fidelity components.
NAME
ADDRESS
Circle 134 on Reader Service Card
nected in parallel, serve as the series
regulator, controlled by an R265A and
a 2N398A, the latter providing some
positive feedback to improve regulation.
Normally the circuit is adjusted for zero
regulation at 15 volts output, which
gives optimum performance over the
entire voltage range. For specific requirements, the adjustment can be made for
any desired voltage, so that regulation is
zero for that specific output voltage.
The fifth transistor serves as the current limiter. Output voltage is selected
in steps of five volts by means of a
switch, and for intermediate values by
a continuously- variable control. The
panel meter serves to indicate both voltage and current-the particular function
being selected by a slide switch while the
full -scale range is set for optimum readability. Thus when the voltage switch is
set at 10 volts, the meter has a full -scale
range of 15 volts; if the switch is set for
40 volts, the full -scale range of the meter
is 50 volts. The current -range switch
similarly sets the desired range, with full scale indications of 50, 150, and 500 ma,
and 1.5 amps, while another continuously- variable control gives intermediate
settings. Once the current and voltage are
set to the desired values, they remain constant. A decrease in load resistance, such
as a short circuit, will cause the breaker
to operate, and current cannot flow again
until the reset switch is operated.
The entire circuit is free from case
ground, eliminating- the possibility of
shorting the supply by inadvertent touching of the unit with a chassis of the
equipment being fed, which usually has
a positive ground with transistor equipment. Three terminals are provided,
positive supply, negative supply, and
case ground. Line fuse and a pilot light
are also on the front panel.
Aside from the obvious uses like powering experimental circuits involving
transistors, when the maximum current
can he set to a given value, with complete
assurance that the safe current value can
not be exceeded, the IP -20 can he used
for many other purposes. We once had
occasion to determine the voltage drop
across a current limiting resistor in a
series- heater string of a TV set in which
the voltage of the picture -tube heater
was unknown. The "cold" resistance of
the resistor in question measured around
2500 ohms. By putting 50 volts across
the resistor and watching the current increase slowly, then gradually reducing
the voltage as the resistor heated to maintain the current at 300 nia (its rated
value), it was found that the stable voltage across the resistor when hot was only
20 volts. With this information, the remainder of the circuit calculations could
be made.
The a.c. ripple in the supply is less
than 150 µv, making it perfectly suitable
for low -level amplifiers. When the unit
is furnishing a current of 1.5 amps at a
given voltage and the circuit is opened,
no "flick" of the voltmeter can be seen.
Observing the output on a scope, a spike
of about 0.02 volts can be observed which
lasts for some 25 ins. Voltage and current regulation remain effective over the
input voltage range from 90 to 135 volts.
For higher currents, two or more IP20's can be connected in parallel with 0.1ohm resistors in the "hot" line from each.
It is then only necessary to adjust both
output voltages to the same value. Sinilarly, two or more units can be connected
in series for higher voltages-this time
with the current -ranges set to the same
value.
Construction
Not more than ten hours should be required to construct and make the final
adjustments to this unit, and on completion it can become an extremely useful
addition to the experimenter's stable of
Circle 162
laboratory equipment
AUDIO
58
www.americanradiohistory.com
SEPTEMBER, 1964
proven quite effective in correcting such
GENERATORS
/ayr
terval, during which an open circuit
(no output) would exist. Because of this
third mode, an alternating design is not
used. The a.c. generator of Fig. 3, and
the d.c. generator to he described (Fig.
8), each have only two modes of operation.
A typical transfer characteristic scope
pattern for a good amplifier to the signal of Fig. 4 is seen in Fig. 5. In this
example the amplifier is driven into hard
clipping by the larger wave, and any
transient bounce is displayed on recovery
as a vertical (up and down) motion
(oscillation) of the small trace about the
zero level. This produces a characteristic pattern which once seen, is easily
recognized. In the case of an amplifier
with poor damping or stability, the oscillation may take several seconds to die
flaws.
Another useful test signal can be made
up using the same apparatus as Fig. 2,
but adding a network after the audio oscillator to convert the sine wave into a
mainly unipolar function. A diode and
resistor allow this change ( Fig. 6A) ,
producing a wave clipped on one side, as
in Fig. 6B. This is fed through the same
transient generator as before, and pulsed
manually in the same way. To change
the signal from positive to negative, as
illustrated in 6B, reverse the diode leads.
The scope patterns will again show
transient effects as a vertical bounce. The
differences in waves. however, shows how
well the device under test handles a complex unipolar transient signal, and in
particular, if there is any major difference between the sine signal and the
unipolar signal pulse response. The need
for unipolar or assymmetrical transient
testing has been pointed out by Crow hurst (Audio Measurements, pg. 11d11.6)
.
A third test signal consists of a d.c.
generator pulse, Fig. 7, which is a com-
pletely unipolar step function transient,
of duration chosen by the operator. The
wave is rectangular, or square. Figure 8
shows the d.c.- generator schematic. The
output level is controlled by the pot,
for the critical recordist...
ANOTHER `FIRST" FROM UNIVERSITY
down.
At the beginning, it will be most convenient to test at the mid frequency
where the characteristic is a straight
line (no phase shift). Later, as the significance of the various patterns becomes
clearer, the test can he done at any frequency. For an amplifier designed to
feed a speaker, use resistive, open circuit, and reactive loads.' For a preamp,
use a resistive load equal in value to the
following grid resistor, which is in the
region of 100k plus. The bounce patterns
obtained should he fairly independent of
frequency.
For further information work both
above and below overload. To wake slow,
continuous changes in amplitude, "wiggle" the pot manually.
Possible very high frequency transient
effects of similar type will normally be
seen at the same time, as a different transfer characteristic non -linearity, in the
form of an oscillation pocket or a
damped oscillation riding on part of the
trace, rather than as an oscillation which
modulates the whole trace up and down.
High -frequency effects should he checked
for with open circuit and reactive loadings, as they are more likely to show up
under these conditions. It should be
rioted that the Crowhurst techniques have
i A reactive load used for testing should
approximate the load presented by a typical dynamic speaker. In Loud. peakrrs, pg.
79 -81, Briggs has shown that at 4:; cycles
a quality 10 -in. speaker on open baffle was
"electrically equivalent to a 20 -ohm resistor in series with a 79 µf capacitor,"
while when mounted in a 2 cu. ft. reflex,
the same speaker was "equivalent to a 24ohm resistor in series with a 33 mh inductor." From this data, taken on a foam suspension unit, we can see that the load on
the amplifier can differ from a pure resistance by a considerable amount. These reactive components change with frequency,
and can degrade both damping and stability of a feedback amplifier.
AUDIO
SEPTEMBER, 1964
THE 8000
¡t4.+0404Ñ
ü
,.
.
.
.
.
.N;
.., ,..,...,
_
....
.
.._
,Nb
.
.,.ë
...
4
w
Y.H
J
44
It's shock -mounted ! It's a dynamic!
It's a cardioid ! And it's only $29.95
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8000 is a cardioid dynamic typical of the finest professional recording
microphones. With its superb directional characteristics, it virtually eliminates background noise. You can work close or far -you will achieve a
degree of clarity and definition you never thought possible before. Response: 70- 13,000 cps. Sensitivity: -156 db (EIA). Output Level: -59 db/
1mw /10 dynes /cm? Includes 15 ft. cable with choice of high or low impedance at the Càrinön plug and receptacle! Includes desk stand adaptor.
Mod. 8000: $29.95-Mod. 8100 with on /off switch: $31.50.
For complete specifications, write Desk R -9A, LTV /University,
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DIVISION OF LING - TEMCO- VOUGHT, INC.
CIRCLE 135
59
and polarity can be reversed by the toggle switch.
With the generator of Fig. 8, the
transfer characteristic patterns were
found difficult to interpret, giving no
clear picture of small transient flaws.
This generator was found useful, however, for the study of gross effects. Here
the test signal is similar to Mr. Briggs'
generator, and for best evaluation either
a memory, photography, or long persistance scope is needed. On amplifiers
it can serve as a final transient test, for
use after the more sensitive a.c. generator method has allowed zeroing in on
correct component values.
In using these generators, it is not desirable to try to attain any kind of speed,
for to be truly informative at very low
frequencies, the repetition rate of the
transient must be long enough for the
damped oscillation to die down com-
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difficult.
The above tests and generators have
been used in the design and checking of
numerous heavily fed -back (20 db) amplifiers, and preamplifiers, to evaluate
low-frequency transient response. In
each case considerable information was
obtained about the stability, damping,
and overload characteristics, and it was
discovered that circuits approaching the
Circle 138 on Reader Service Card
SEARCHING?
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in a current, or even not -so-current, issue of
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a
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LECTRODEX, the original radio- electronic
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the subject you want, and it costs you only
pennies per issue of LECTRODEX.
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teachers, studenu, researchers, hobbyists and
technicians in the radio-TV-electronic fields have
magazine
ideal condition (no vertical bounce),
gave excellent results.
In many cases it was found that the
basic circuit under test could not be
made to pulse well, even with the most
careful adjustment of time constant values. These circuits were therefore aban-
referred to LECTRODEX for information about
articles from amplifiers to zener diodes.
LECTRODEX covers more than twenty -five publications
in the radio and electronics fields and is published bi- monthly
as a cumulative index throughout the year with the 6th or last
issue as an Annual which may be kept as a permanent record of
all radio -electronics and related articles published that year.
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pletely before the next pulse is applied.
This means that if the bounce lasts for
say 2 seconds (a very bad case), the
second pulse should not be started before
this. In this way the equipment under
test has a chance to return to a steady
or quiescent state before being "hit"
again.
More rapid repetition rates- preferably non-uniform, to avoid approximating a steady -state condition-can of
course be used, but because the patterns
are faster, interpretation becomes more
Generator
1
SPOT
NORMALLY -OPEN
PUSHBUTTON SWITCH,
SWITCHCRAFT FF -1001
500 POT
1
.
to produce the step
waveform of Fig. 7.
AUDIO
SEPTEMBER, 1964
doned, and others tried, until a better
one was found.
A surprising case was that of a pre amp of "fine" quality, which exhibited a
more serious bounce at low levels than
most of the power amplifiers at high levels.
New
Futterman
Model H -3 OTL
Stereo Twin -50
Consider a vaz.t,um tube
power amplifier Si "good" it
can readily proie its absolute
superiority
livrer any other
(whether tube o transistor) on
the market today...Indeed, an
amplifier so 'good" that the
line between physical limitation and theoretical 3erfection
is, for all practicEI purposes,
erased. In short, consider the
revolutionary new Futterman
Model H -3.
a frequency response of +0,
db from 5 to 90,000 cps and
db at 200 Kc...with harmonic
With
-0.5
-3
and intermodulation distortion so
close to zero that it is virtually unmeasurable...with a signal -to -noise
level that is better than 90 db
below 50 watts...with an unprecedented damping factor of 200...
with a square wave response that
has never been approached by an-
other amplifier...with a unique
patented tube circuit that does
not require the distortion- producing transformers that are integral
to all conventional amplifiers ...
with a built in stability that is absolute proof against the severest
of load configurations and conditions...with a power output very
conservatively rated at 50 watts
RMS per channel (15 or 16 ohm
load)... with all this, the new Model
H -3 is truly the ultimate amplifier.
Quality construction is basic
to the Model H -3. Every component
and part is made in the U.S. and
is of the highest grade obtainable.
Meticulous care is taken in the
fabrication and testing of each H -3
amplifier and each is backed (except for tubes) by a full two year
warranty.
The price (incl. cage):
$288.
For further details,
write:
Dealer
inquiries
invited
harvard 4:41
electronics co.
693 BROADWAY, N.Y., N.Y. 10012
Circle 136 on Reader Service Card
AUDIO
With the techniques and devices described in this article, it is possible for
the designer or builder to obtain a clear
comparative picture of these defects, and
to effect a "cure." In particular, the bass
transient response can be readily observed and evaluated.
Æ
DYNA
MIKES
Professional
ribbon microphones
by B &O
at realistic prices
ABOUT MUSIC
(from page 14)
revelation, Bean received only one critical letter; the writer complained, not
about the results of the experiments, hut
about the fact that they had been conducted secretly.
The news of the experiments was made
public on May 7th. From then until the
end of the month, the system was used
continuously. On the basis of the reactions of musicians, critics and the general public, the London County Council
has decided to install the resonators permanently and to explore the possibility
of extending the system to span the entire musical range.
Bean is understandably pleased with
the outcome of the tests. "However," he
remarked, with a jaunty smile, "I have a
strain of skepticism, you know. I'll wait
a couple of years for the final results."
The Building Research Station is more
sanguine about its achievement. It points
to two technical advantages over other
sound reinforcement systems
(1)
"[each] loudspeaker has to reproduce
only one frequency; i.e. not even only
one note with all its harmonics, but only
one frequency. Thus the biggest weakness of loudspeakers -their inability to
reproduce the whole frequency range of
music without some variation or distortion however slight
overcome . . .
(2) This system works in the auditorium
proper; there is no question of using
microphones to pick up orchestral sound
directly, and thus there is no need for
any `balancing' of the musical sounds.
"If this new system works," the Building Research Station concludes, "the musician will be able to play a more active
part in the acoustical conditions of the
hall, at least as far as the reverberation
is concerned, because the reverberation
need not be determined until the hall is
finished." (italics mine)
The implications are obvious. Such an
approach could revolutionize prevailing
concepts of acoustical design. Unfortunately, I arrived in London too late to
hear the "new sound" in the Royal Festival Hall. This will have to wait for
next year.
Æ
:
-is
SEPTEMBER, 1964
The choice of microphone affects the naturalness or accuracy
of sound recording more than
any other factor, with even the
least expensive tape recorders.
The superiority of ribbon microphones has long been acknowledged in affording full frequency response and maximum
dynamic range without the
harshness or stridency often criticized in far more expensive
microphones.
The finest sounding ribbon microphone is the Model 200
DYNAMIKE. This compact,
versatile instrument is ideal for
natural stereo recordings with
minimum effort. Two identical
ribbon elements may be rotated
up to 90° to each other for
either conventional or MS stereo
pickups with optimum separa.
tion and precise instrument localization. The top element is
removable for mono use. These
precision elements are renowned
for extraordinary range and
smoothness (unfortunately, response specifications are meaningless, since cheap mikes advertise far wider range than the
best ones), a perfect figure 8
pattern, and uniform polar response over the range. Professional low impedance 200 ohm
output enables long cables without hum or interference . .
$149.95.
For over a decade B &O ribbon microphones have been the choice of broadcast
stations, recording studios and record
manufacturers on both sides of the Atlantic wherever a premium quality microphone was demanded. DYNA believes
they offer the amateur recordist the same
value which has characterized DYNAKIT
amplifiers and tuners. Ask to hear the
Model 200, or other DYNAMIKES from
$59.95 at your high fidelity specialist, and
watch for the new DYNA -B&O tape recorder-a home machine which can take
full advantage of the performance of
these fine microphones.
Write for detailed specifications.
DY N ACO I NC.
3912 Powelton Ave., Phila., Pa. 19104
Circle 140 on Reader Service Card
61
www.americanradiohistory.com
convenient service to AUDIO readers.
A
HE
." L-
-
AUDI
ii. iiii
Designing and Building Hi -Fi furniture
Jeff Markel
Written by a professional
hi -fi furniture designer
who has taught furniture
design at leading colleges, this book is an authentic reference of value
to the hi -fi fan and professional custom builder.
Covers everything from
types of woods to furniture finishing for the
Maintaining Hi -Fi Equipment
Joseph Marshall
A valuable reference for
anyone whose living or
hobby is servicing hi -fi
equipment. Outlines the
professional approach for
servicing all types of hifi components. Covers
trouble -shooting of elec-
tronic, mechanical and
acoustic problems. 224
pages.
No. 58 Paperback $2.90*
.:
. Al,
,
Order your books leisurely
save time and travel,
by mail
we pay the postage.
'
BOOKSHELF
a
,
e
i
1°
1280 pages
1600 topics
1600 illustrations
"The AUDIO Cyclopedia"
Howard M. Tremaine
-
Here is one single volume
with the most comprehensive coverage of every
phase of audio. Concise,
accurate explanations of
all audio and hi -fi subjects. More than 7 years
in preparation -the most
^
l
I
1
U
authoritative encyclope-
dic work with a unique
quick reference system for
instant answers to any
question. A vital com plete reference book for
mechanically adept; design principles, styles and
arrangements for the
decor minded. 224 pages.
No. 79 Paperback $2.90"
.,
;q,z
every audio engineer,
technician, and serious
No. 123 $19.95*
audiophile.
The 6th AUDIO Anthology
The 5th AUDIO Anthology
_...
Edited by C. G. McProud,
publisher of AUDIO. An anthology of the most signifi-
High Fidelity Omnibook
Prepared and edited by
C. G. McProud, publisher
of Audio and noted authority and pioneer in
the field of high fidelity.
Contains
a
wealth of
ments; stereo technology,
construction and theory
which appeared in AUDIO
during 1958 and 1959. The
5th is truly a collectors' item
and a valuable reference for
the professional engineer,
teacher, student, hobbyist and
hi -fi fan. 144 pages.
-
"the best of AUDIO"
"PE
AUDIt1GIIIDE
Puna
a_w
-
techniques, sound effects,
editing and splicing, etc.
Invaluable to recording
enthusiasts.
No. 112 Paper Cover $2.95*
MONTHLY SPECIAL! SAVE $5.00
50% with this collection of AUDIO books.
"best of AUDIO" ($2.00)
5th AUDIO ANTHOLOGY ($3.50)
McProud High Fidelity Omnibook 1$2.50) and
Tape Recorders & Tape Recording ($2.95)
POIN'
`.r_
,-
www
u-.-
No.
1
27
$
the editors of AUDIO, the
magazine about
high fidelity. A 1962-1963
product review of stereo high
fidelity components. Valuable
fi
reference for the hi
ity enthiast and hobbyistdel-.
Part I contains a thorough
discussion of the Problems of
a Stereo Installation; Part II
is o
complete treatise on
Selecting a Tape Recorder.
Indispensable to the prospecfive buyer of stereo components and tape recorders.
Includes a section on where
to buy various stereo hi -fi
components and accessories.
156 pages.
original
,..
-
corders. Covers room
acoustics, microphone
$3.95
By
AUDIOGUIDE
new compendium of
AUDIO knowledge. Here
is a collection of the
The
best of AUDIO
AUDIO Clinic by Joseph
Giovanelli . . . noted
audio engineer and the
original high fidelity answer -man
EQUIPMENT
PROFILES edited by C. G.
McProud . . . Editor of
AUDIO. Here is a wealth
of hi -fi and audio information. Answers to the
most important issues in
high fidelity and a valuable reference.
No. 124 Volume I $2.00`
of high fidelity: FM STEREO
and TRANSISTORS IN AUDIO
EQUIPMENT. A meaningful
reference for everyone in the
fields of audio engineering,
recording, broadcasting, manufacturing and servicing of
components and equipment.
A necessary
book for the
high fidelity enthusiast. 144
No. 130
A
A complete book on home
recording by the author
of High Fidelity Simplified. Easy to read and
learn the techniques required for professional
results with home re-
RECORDING
-
edited by C. G. McProud
1.00
'
usgh
High Fidelity Simplified
Harold D. Weiler
3rd Edition
Save almost
TOTAL VALUE ALL FOUR BOOKS . . . $10.95
Your cost only . . . $5.95 Postpaid
This offer expires October
3
1 ,
1964, and
is
good only on direct order to the Publisher.
CIRCLE 05400
P.
INC.
O. Box 629, Mineola, New York 11502
Please send me the books
full remittance of
58
125
I
have circled below.
$
79
127
112
130
I
*AII U.S.A. and Canadian
orders shipped postpaid.
tuners, changers, amplifier
recorders, speaker'
record players, etc. Lots r
ideas for custom installs.
lions. Tells how to achieve
concert hall reception i.
your home. 216 pages.
$3.30
It
I
/!-
fir
'r
,
tl III
Í
°-
i r...r
¡
4r.r
Herman Burstein
Written in "plain talk" for
(No C.O.D. or billing.)
115
123
251
124
0S400
TAPE RECORDER
'
s' '
t
NAME
;
....=
-_,
[P.
-.,
;.,
t-°'
. -+!:
'
-
ADDRESS
CITY,
NICfl
N
Getting The Most Out Of Your Tape Recorder
sff.gh mveu4J '-
am enclosing the
142
_-77:7The complete hi-fi story answers all questions abo.
No. 142
AUDIO Bookshelf -RADIO MAGAZINES,
McProud,
G.
publisher of AUDIO. Includes
articles on the two most signifcant milestones in the field
pages.
$3.50
No. 125
Tape Recorders and Tape Recording'
Harold D. Weiler
RECORDERS,
MIRI(t
IIUUlu
hí, %J
cant articles covering: stereo
recording and reproduction;
stereo multiplex; measure-
ideas, how to's, what
to's, and when to's, written so plainly that both
engineer and layman can
appreciate its valuable
context. Covers planning,
problems with decoration,
cabinets and building hifi furniture. A perfect
guide.
No.115 $2.50"
PIPE
Edited by C.
STATE
ZIP
www.americanradiohistory.com
lions raised by tape recording enthusiasts. Its chapters
cover every phase of operalion and maintenance -from
adding a tope recorder to
the hi-fi system, to a thorough dissertation on microphones. Lots of practical
information on how to buy.
176 pages.
No. 251
AUDIO
62
1
the man who has, or wishes
to buy, a tape recorder. It
answers the myriad pues-
$4.25
SEPTEMBER, 1964
WEBCOR
professional
NOTE ON CURVE PLOTTING
(from page 24)
was the case with the particular standard. What is called for is a curve conforming with the admittance of a series
combination of a capacitance and a resistance having a certain time constant.
Since the desired curve is one expressed
in decibels, one has to consider not pure
admittances, but ratios of admittances,
as follows:
Circuit "A" of Fig. 1 shows a series
R -C circuit whose absolute value of impedance is given by :
Z=Rr1+1 cuCR)2]L Eq.
(1)
The time constant, T, of the discharge
of a capacitor through a resistor is defined as the time required for the voltage or current to decay to 1/e = 0.3679
of its value. For the charge of a capacitor, the sanie definition applies, the
voltage "decaying" toward its steadystate value. The finie constant of discharge or charge of the current in an
inductor through a. resistor follows a similar definition. Without going through
the oft -published computations for these
circuits, we may write
T
I,
R
CR
Eq. (2)
Substituting Eq. ( 2) in (1) we obtain
Z =R[1
+(- )211
1
wT
To plot the impedance variation with
frequency in decibel fashion, we must
know the impedance at a frequency when
the reactive element has a negligible effect, that is, when the resistance is the
controlling element. This we may do by
writing
db= 20lagR r10log
1+
(
-2)
T
The equation for the admittance response, expressed in db, is the saine as
the equation above, except for a minus
sign, because the admittance is the reciprocal of the impedance.
What remains to be done is to plot the
curve for the time constant T = 0.00318
seconds as given by
L1
N
\\
+I 2nfx0.00318
We may similarly plot the admittance
response for a parallel combination of
a capacitance and a resistance having a
time constant of 50 microseconds to
achieve the desired high -frequency response. The values can be obtained directly from the curves of Fig. 1 and introduced in the field of Fig. 2. The solid
line of Fig. 2 represents the modification of the 6 -db- per -octave curve in accordance with the prescribed test for
the magnetic playback characteristics of
1/4 in. tape travelling at 71/2 inches per
second.
IT-
6db /OCTAVE
ADM TTANCE
RESPONSE
--
10
// ' '
0
T
ADMITTANCE
}
50P SEC
RESPONSE
.M.A.
*T
-3180p
N.
SEC
N.
N
N.
-70
Sound, Style,
e
1
db=-10log
30
2C
The Ultimate in
s
\
Stereo!
Make all the tests you want, or just listen
either way, you'll agree that the Webcor
Professional is the ultimate in a professionally oriented tape recorder and reproducer.
Here are some of the reasons
'/a track
track
1/a
stereo; record and playback
monaural; 4 track record and playback
simultaneous record and playback in monaural echo effects in monaural synchrostereo
track and "sound with sound"
stereo public
and reverse stereo play
address system automatic thread control
and combination on /off /ASO Push button
reset digital counter tape lifters. Plenty
of others, too -including 3 speed operation,
2
separate "stereo- supreme" speaker
wings, keyboard control, tilt -out amplifier
panel and computer type reels. All that and
the most elegant design in the field. Test
the Professional at your Webcor dealer
soon. Or if you like, just listen. Either way,
you'll love it! Under $500.00.
s'1
N.
Widen your world with
_.0
20
100
1000
FREQUENCY IN CYCLES PER SECOND
10
10000
20000
WEBCOR
Webcor, Inc., 700 North Kingsbury /Chicago 60610
Fig.
AUDIO
SEPTEMBER, 1964
2.
Composite curve.
Circle 141
63
Acoustech Solid State
"...better than the best..."
-Hi
Fi /Stereo
Review
Amazing Amplifier
Offers World's
Finest Sound For
Only $299
Important news for the discriminating
music lover! The new Acoustech V Control Amplifier, for only $299, provides
matchless sound, unbelievably low distortion (less than 0.5% IM at 30 watts RMS),
and almost 125 watts of instantaneous
transient power per channel. Every orchestral crescendo easily handled with
even the most inefficient speaker system.
Acoustech's solid state circuitry makes
this amazing performance possible in an
integrated Control Amplifier, half the
price of nominally equivalent tube units.
Shown on scope in above photo is an
actual waveform of a 125 watt transient
signal perfectly reproduced through the
new Acoustech V.
*/i ACOUSTECH
NEW LITERATURE
Tape Recorder Booklet. Literature on
the new Freeman Model 800 stereo tape
recorder, priced at $299.50, is now available
from the company. Specifications, features
and photos of the three -speed Model 800,
which records up to 24 hours of background music on a single seven -inch reel,
are fully detailed in the literature offered,
on request, by Freeman Electronics Corporation, 729 N. Highland Avenue, Los Angeles 38, California.
Circle 208
Enlarged Condensed Semiconductor Catalog. Anrperex Electronic Corp. has announced the publication of their new condensed semiconductor catalog. Much expanded over previous editions, the new
catalog is now 48 pages and contains much
new material in addition to all the basic
specifications of the full line of Amperex
transistors, diodes and photosensitive devices. New chapters include: How to
choose a photo- sensitive device; parameter
conversion tables; circuits utilizing Amperex semi -conductors (i.e. chopper, differential amplifier, AM -FM receiver, sonobuoy transmitter); a full list of available
Amperex application reports; outlines
with measurements of all semiconductor
envelopes used by Amperex; and on the
back cover, a listing of Amperex sales
representatives. Free copies of the condensed Amperex Semiconductor Catalog
may be obtained by writing to Amperex
on Company letterhead. Amperex Electronic Corp., Advertising Department,
Hicksville, Long Island, New York 11802.
Circle 209
New Brochure Contains Sample. A
unique brochure is now offered by Shakeproof, Division Illinois Tool Works Inc.,
on the company's line of TEKS self- drilling fasteners. The ingenuous thing about
Shakeproof's new brochure is that it contains actual TEKS testing samples. Complete instructions are contained in the
brochure detailing the method of application, equipment required, and drill
speeds so that the samples can be removed and driven. TEKS -by- Shakeproof
are said to do three jobs at once. They
drill their own holes, tap, and fasten in
one assembly -line operation. TEKS look
like a screw, drill like a drill and reduce
assembly costs, Shakeproof claims. For a
copy of Shakeproof's TEKS sample -containing brochure, write: Shakeproof, Division Illinois Tool Works Inc., St. Charles
Road, Elgin, Illinois 60120.
Circle 209
Xcelite Product Bulletin. An illustrated
product bulletin from Xcelite Incorporated
contains description, photo and price information on new Electronic Snips for
cutting fine wire and filaments and stripping insulation in electronic assembly and
service work. The snips are described as
also being useful to hobbyists, electricians and jewelers for cutting not only
wire but sheet metal and other light materials up to 0.025" thick. Bulletin N464 on
the No. 86 Electronic Snips may be obtained by writing Xcelite Incorporated,
Orchard Park, N. Y.
Circle 210
Tape Recorder Brochure. Newcomb Audio Products has produced a two -color
brochure describing its TX10 Series
stereophonic tape recorder. Newcomb Audio Products Co., Hollywood, Calif. 90038.
Circle 211
ACOUSTECH, INC.
Cough
too
much ?,
Dept. A -9, 139 Main Street,
Cambridge, Mass. 02142
FREE
Please send free booklet "Why Solid State Amplifiers Can Sound Better" and full information on
Acoustech V to
Short
of
breath?
Name
Address
City
Zone
State
You may have a Respiratory Disease.
Don't take chances, see your doctor,
says your Christmas Seal association.
CLASSIFIED
Rates: 10e per word per Insertlon for noncommenlal
advertisements; 250 per word for commercial advertisements. Rates are net, and no discounts will N
allowed. Copy must be accompanied by remittance in
full, and must reach the New York office by like
first of the month preceding the date of Issue.
HIGH FIDELITY SPEAKERS REPAIRED
AUI'IIITE SPEAKER SERVICE
168 W. 23rd St., New York il, N. Y.
CH 3 -4512
MILITARY DISCOUNTS : name brands.
Free recording tape and stereo handbook. Include rank, serial number. Electronics International, Inc., Box 3066 Charlottesville, Virginia.
HI -FI COMPONENTS, tape recorders at
guaranteed "We Will Not Be Undersold"
prices. 15 -day money-back guarantee, 2 -year
warranty. NO CATALOG. QUOTATIONS
FREE. HI- FIDELITY CENTER. 1797 -V 1st
Ave., New York, N. Y. 10028
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 Harpsichord, Dept. R, 115 Christopher St., New York 14, N. Y.
ALTEC 288 drivers $75 each. Kloepfer, 724
Governor Nicholls, New Orleans, La.
LEARN WHILE ASLEEP Hypnotize with
recorder, phonograph Details, strange catalog
free. Sleep-Learning, Box 24 -AE, Olympia,
Washington.
:
!
SARKES TARZIAN'S Galaxie tensilized
mylar : 1800', $1.69, 2400', $2.79, 3600', $3.89.
Postpaid, guaranteed. Famous components,
discount prices. Catalog free. POFE, 1716
Northfield, Muncie, Illinois.
FOR CONTINUOUS MUSIC WITHOUT
COMMERCIALS : Build a suhcarrier adapter
for your FM equipment. Standard parts. Complete text with schematics, $3.00. Wired
adapters, $75. Kits, $45. Music Associates, 65
Glenwood Road, Upper Montclair. N. J. Telephone 744 3387 area code 201.
RCA 25 watt amplifier, MI -12298 (modified) : 7 inputs ; 4 mixers; 3 microphone pre-
amplifiers with transformers tone control
cage. Electrolytics, much wiring brand -new.
Less 10 tubes. Cost $300. asking $100. Jay
Rose, 7 Southgate, Great Neck, N. Y.
;
;
SELL : Jensen P15-LF Flexair woofer front
mounted in 6 cubic foot walnut enclosure.
Very handsome and extremely rigidly constructed, suitable for any quality high frequency unit. $70. Francis Daniel. 207 W. 106
Street, New York 25, N. Y.
KITS ASSEMBLED. Wendell Brase, Lake
Mills, Iowa. Write for quotations.
SAVE YOUR
COPIES OF
AUDIO
Each file holds a
full year's copies.
Jesse Jones
ume
Attractive and
practical for your
home or office
Vol-
Files for every
3
publication.
leather like Kivar,
title embossed in 16
Kt gold.
Satisfaction guaranteed
F R E E
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6
Covered in durable
for $13.00
ORDER NOW-send
check or money order
MAGAZINE FILE CO.
520 FIFTH AVENUE
NEW YORK 36, N. Y.
Colt
UEP
NATRVEOFUESFIT
CIRCLE 142
64
AUDIO
SEPTEMBER, 1964
CORRECTIONS TO
AUGUST LISTINGS
The following cross references were
not included in the manufacturers and
importers listing in the Product Preview
Section of the August issue.
ADC (see Audio Dynamics Corp.)
EMT (see Gotham Audio Corp.)
Finco (see Finney Co.)
JBL (see James B. Lansing, Inc.)
LTV University (see University Loudspeakers)
3M (see 3M Company)
Norelco (see North American Philips
Co.)
Omega (see Stanford International)
PML (see Ercona Corp.)
Radford (see Lectronics of City Line
Center)
Schoeps (see International Electro-
acoustics)
Stentorian (see Barker Sales)
Soundcraft (see Reeves Soundcraft
Corp.)
Transwave (see Transistor Sound Laboratory, Inc.)
Uher (see Martel Electronic Corp.)
Weathers (see Telepro Industries)
Cecil E. Watts (see Elpa Marketing)
Wollensak (see 3M Company)
No addresses were given for 3M Company and Superex. They should be :
3M Company
Magnetic Products Division
Bloomfield Hills, Mich.
Superex Stereo /phones
Radford Place
Yonkers, N. Y.
Do not address inquiries about YL to
the address in Japan. Instead send them
to :
Provo High Fidelity
P. 0. Box 204
Batavia, N. Y.
Langevin was described erroneously as
an affiliate of Altec Lansing. Its correct
name and address are :
Langevin, A Division of Sonotee, Inc.
503 South Grand Avenue
Santa Ana, Calif.
REK -O -KUT was credited with making
a kit, Model R -3411 at $69.95. It should
have been K -3411 at $59.95.
CANADA
High Fidelity Equipment
Complete Lines
Complete Service
HI-F1 Records
Components
E;LECOO10E
SOUND SYSTEMS
and Accessories
126 DUNDAS ST. WEST. TORONTO. CANADA
CIRCLE 146
AUDIO
Raymond Pepe Dies
As we go to press, we learned the
sad news that Raymond V. Pepe
died of a heart attack in Los Angeles on August 15, 1964. Ray was
Chairman of the Board of Directors
of the Institute of High Fidelity and
a past President. He was also Vice
President of James B. Lansing
Sound, Inc. He is survived by his
wife and infant child.
Janszen Joins Acoustech. Morley D.
Kahn, President of Acoustech, Inc., announced that Arthur A. Janszen has
joined the firm as Vice President and Director. Janszen has been consultant to
Arthur D. Little, and held positions as
Special Research Associate at the Harvard
Underwater Sound Laboratory, Associate
Professor of Engineering Research at
Pennsylvania State College, Senior Research Assistant at the Harvard Acoustics
Research Laboratory, President and General Manager of Janszen Laboratory, Inc.,
and Vice President and Director of KLH
Research and Development Corp.
Koss New Rek -O-Nnt President.-Will
Move Plant. Reflecting changes of a new
controlling shareholder, Rek -O -Kut Co.
Inc., pioneer manufacturer of high fidelity
turntables announced major new operations plans at a stockholder meeting.
Stockholders elected John C. Koss as new
president and board Chairman. Koss, Milwaukee manufacturer of Koss Stereophones, recently purchased controlling interest in Rek -O -Kut from George Silber,
former chief executive. The company had
been operating under Chapter XI of the
Federal Bankruptcy Act since May, 1963.
Koss has settled the outstanding liabilities
with creditors and told stockholders he is
now preparing application for removal
from Chapter XI status. Koss also announced that steps would be taken immediately to move the manufacture of Rek O-Kut products to his Milwaukee plant. "I
see no question," he said, "that manufacturing, administrative and marketing economics can be effected by fabricating the
line in Milwaukee. This will mean a measure of financial relief in addition to the
boost we expect from sales increases."
Koss indicated that his production executives were currently studying the problems
of a 900 mile corporate move and that it
appeared all facets of operation would be
in the midwest by November 1.
ERSIN
ERSIN
FIVE -CORE
'
SOLDER
Sold only by Radio Parts Distributors
*Based on cost comparison in current catalogs.
MULTICORE SALES CORP., PORT WASHINGTON, N
CIRCLE 147
Y.
me
Write For Our Price Now.
Save
YOU'LL BE GLAD YOU DID.
Up to 24 mos. to pay
over
day money-back guarantee.
Full 2 yr Warranty-Parts
& Labor.
Factory Franchised all
lines. We ship from stock.
Trade -ins Highest allowance-Send your list.
19th year of reliable service- world -wide.
We guarantee "WE
15
40%
on
hi-fi L
WILL NOT BE
UNDERSOLD."
Best Buy.
HI- FIDELITY
This handsome wall unit graces the
home of Paul A. Wassman of Hyattsville, Maryland. The wood work was
done by the Wood Shop, Silver Spring,
Maryland. It is all walnut and shelving
can be placed in any desired location.
Components are as follows, starting
top left and 'working to the right, EICO
RP-100 and Bell T347 tape decks, Citation IV preamp, H. H. Scott 350 FM
tuner. Hidden behind sliding door at
lower right is a Citation V power amplifier. The speakers are Electro -Voice
EV 6's.
1797 -U 1st Ave.
New York, N. Y. 10029
L---------------J
CENTER
COVER INSTALLATION
Hi -Fi List Ere..
"The rouse ai ww
La. Prices"
CIRCLE 144
FAST SHIPMENTS
TIME PAYMENTS
COMPONENTS
KITS
BEST -BY- COMPARISON PRICES.
VISIT
OUR
STORE
FACTORY SEALED CARTONS
SEND FOR "QUOTES" ON PACKAGE
DEALS AND SAVE MORE
WRITE FOR MONTHLY SPECIALS
/7
CA/45TON
-tut;oe,
125 -A East 88 St., New York 28, N. Y.
CIRCLE 145
65
SEPTEMBER, 1964
www.americanradiohistory.com
STUDIO
TALK
ADVERTISING
by Art Davis, Vice President
A
u d
o
C o n
t
r o
s
D
v
i
s
i
INDEX
o n
Altec Lansing Corporation
i
l
i
SUPERIOR NEW INSTRUMENT
SWITCHES AND ATTENUATORS
It's no longer a secret that our
Audio
Controls Division at Altec is well on the
way to producing what we feel will be the
best instrument switches and attenuators
ever made specifically for the recording
and broadcast industries. Without wishing
to detract from my own three decades as
a design engineer and manufacturer in
this field, nor from the superb facilities
available to me at Altec, I must admit that
much of the credit goes to the fact that
we are starting from scratch on all of
our designs. Frankly, this is an engineer's
dream -no preconceived ideas, no old
designs that have to be adapted, no existing tooling that has to be used. Our only
concern is the here and now, and how can
we make it better.
LOW NOISE, LOW MAINTENANCE,
LONG LIFE
Looks like our switches and attenuators
will give you the best set of performance
specifications ever available. Here are a
few of the things we've done to achieve
this superiority: Each brush blade is independently sprung to provide contact all
the time. We predict a total absence of
contact bounce. The brush springs are
completely out of the circuit and will carry
no current. Our brushes are made of fine
silver ( "coin" silver, normally used, contains copper and is subject to oxidation
which reduces conductivity and raises
noise level among other things). The fine
silver does not oxidize -it sulfides. This
has two advantages: conductivity is not
affected and sulphide of silver has a lubricative quality which is actually beneficial.
MORE INNOVATIONS
As you know, most switches come in
round cans. We're putting ours in square
ones. You don't have any use for the
space around the can anyway so we're
using the corners for the wiring. The result
is that our switches will give you more
positions in less space. For example, most
switches have 12 positions at the most.
Ours have 31 positions on a 11/2" switch
and up to 45 positions on the 21/4 " one.
To cap the whole thing off, we'll be able
to gang up to 8 of our attenuators in tandem so you can operate the whole works
with just one control.
NEW SOLID STATE 470A PREAMP
NEARLY READY
We announced this device in our last
"Studio Talk:' It's the one you can use as
a preamp or as a line, booster, or program
amp with no internal changes needed. By
the way, the 470A has a lower noise level
than any vacuum tube unit on the market.
And by the time you read this, our 61A
Program Equalizer and 62A Graphic
Equalizer will be in full production. So give
me a call or drop me a line. I'll be happy
to send you the latest information on
what's here now and what's coming soon.
Art Davis
Audio Controls Division Altec Lansing
Corporation Anaheim, California
ALa
1964
Acoustech, Inc.
Acoustic Research, Inc.
Acoustical Manufacturing Co., Ltd.
AKG of America
Altec Lansing Corporation
Audio Bookshelf
Audio Engineering Society
Audio Originals
Barker G Williamson, Inc.
Benjamin Electronic Sound Corp.
Bozak
British Industries Corp.
64
58
45
56
15, 66
62
LISIEN
50
6
57
..
III
Coy
66
3
Carston Studios
Classified
Concertone
65
Dynaco, Inc.
61
EICO Electronic
29
SCHOEPS
MICROPHONES
64
Technical data can only
give you the characteristics
of o microphone -data can't
describe your most important
factor
the sound. Get a
Schnaps Microphone on a
30 day trial
and listen I
you will receive This with your
7
-
-
Instr. Co.
Electro- Voice, Inc.
Electro-Voice Sound Systems
Elpa Marketing Industries
Empire Scientific
Coy. IV,
Designed by Schoeps
Manufactured by Schoeps
Patented by Schoeps
1
65
48, 49
33, 34
Fairchild Recording Equipment Corp. 54, 55
Finney Company
4
Fisher Radio Corp.
microphone
9
gQaONPg
Shown: the M2218 with MK26
333
NUN
AVENUE
51
MEW YORK
212 WA 94364
14, M. Y.
Harvard Electronics Co.
Hi Fidelity Center
61
International Electroacoustics, Inc.
66
Jensen Manufacturing Company
39
Kenwood Electronics, Inc.
10
3
65
Koss Rek -o -Kut
5
Lafayette Radio
60
Lansing, James B., Sound, Inc.
LTV University
11
build
your own
bozak
59
42, 43
3M Company
McIntosh Laboratory, Inc.
Multicore Sales Corp.
53
65
North American Philips Co.
41
Pickering
17
Company, Inc.
Revere- Wollensak
Rye Sound Corp.
30,
URBAN OR EARLY AMERICAN
INFINITE -BAFFLE SPEAKER CABINETS
31
60
Scott, H. H., Inc.
Coy. II
Sherwood Electronic Laboratories, Inc. .. 18
Shure Brothers, Inc.
25, 27
Webcor
63
For the Bozak 2 -way B 300
and 3 -way, B -302A Speaker
PRINTED BY BUSINESS
PRESS, INCORPORATED
Systems. Complete Kits for
easy assembly and finishing.
See your Franchised 8ozak Dealer DARIEN
Circle 148
66
capsule
Circle 149
Gotham Audio Corporation
Garrard Sales Corp.
Cr
-3 pattern
INTERNATIONAL ELECTROACOUSTICS INCORPORATED
/
CONNECTICUT
Circle 150
AUDIO
SEPTEMBER, 1964
Q
U
V
More gentle than
people
12"
These are the
famous feathertouch
push buttons which
program the
automatic functions
of the Miracord.
The lightest touch starts the Miracord. You press the 7 button for 7 -inch
records. the 10 for 10 -inch records, or the 12 for 12 -inch records.
With the short spindle in position, 0
the Miracord plays single records
automatically. At the end of play,
the arm automatically returns to
its rest, and the unit shuts off.
A light touch to the stop
button does it sooner.
With the short spindle reversed, the 0
Miracord repeats the same record
continuously, until you remove the
arm manually, or press the stop button.
With the long spindle inserted, you can play
up to ten records in sequence. As each ends,
the next one starts. Or you can press the
button again to reject a record at any time,
and bring the next record into play position.
401
However, you don't have to use
the push buttons if you don't
want to. You can also use the
Miracord to play single records
manually. It's all up to you. But,
once
you have the feel
of the push buttons,
you will never touch
the arm again.
They're
gentler
than
people.
BENJAMIN
M RACORCO
1
SO
Try it at your hi -fi dealer, or write:
Benjamin Electronic Sound Corp.
Swaim Street, Westbury, New York
Sole U.S distributor for Miracord turntables, Elac
cartridges and other Electroacustic® audio components.
Circle 101 on Reader Service Lard
www.americanradiohistory.com
nunnnnmi
Radio - Electronics
NiFi/SteePeoReview
1884
February,
February, 1964
"li
wth
E -V TWO's produce a quite spectacular sound
big, low -down bass...that is the best, to my ears, that
brief, the
a
Electro -Voice has yet produced."
June, 1964
"...the
designers of the
-V TWO were aiming
for a smooth, uncolored
r POPULAR
SCIENCE
E
sound, and they have
succeeded very well.
Overall'the E -V TWO is
a very smooth and musical reproducer."
r
"...the
AUDIO
June, 1964
"They effortlessly fill my
large listening room with
clean, well -balanced sound."
L
Electro -Voice Model
SIX is as close in sound to
a Patrician as one can come
without being
a
Patrician.
You listen."
April, 1964
J
©1964, Popular Science Publishing Co..
r
"(I)
high fide*
"Reproducing test tones,
the Model SIX was found
to have a remarkably smooth,
clean and uniform response
April, 1964
across the audio range!...
But whatever one's personal listening tastes are, it would
seem there is an E -V model to suit them."
Re
rd Guide
have found them to
be smooth and easy -to-
listen -to...
I
found the
top end very smooth and
silky, not overbright, and
1963
December,
also it extended well Beyond the 15 -kc. cla im of the manufacturer."
If Speakers Could Blush, Ours Would!
E -V
-v roue
TWO
$151.87
$120.00
Read what the critics say about the new E -V TWO, E -V FOUR and E -V SIX acoustic suspension
speaker systems. Then conduct your own impartial listening test. For a complete set of
review reprints, plus the name of your nearest franchised E-V hi -fi showroom, write us today.
ELECTRO- VOICE, INC., Dept. 944A, Buchanan, Michigan
Cmrcle 102 on Reader Service Card
www.americanradiohistory.com
gke,t4PYCICZ.,
49107
SETTING NEW STANDARDS IN SOUND
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