Mar - American Radio History

Mar - American Radio History
MARCH, 1956
500
u
ENGINEERING
MUSIC
SOUND REPRODUCTION
The how and why of bass and treble tone controls is told ìn this chapter of "Souni"-page 36.
No one is ever satisfied with his speaker sbstem for inure tlmn a }ear,
it appears. One reader tells us how he improved his. See page 22.
-A
new column about records
JAZZ BY JEAN
HOW LOUD IS SOUND?
THE ARTISTIC INTEGRITY OF THE RECORD
TRANSFORMER DESIGN FOR ZERO-IMPEDANCE AMPLIFIERS
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A N T O N
I
STRADIVARI:
O
C R A F T S M A N
M A S T E R
This master craftsman brought the art of violin making to its highest pitch of perfection. The Stradivari method
of violin making created
a
standard for all times; but the secret of his varnish, soft in texture, and shading from
orange to red, though much investigated, has remained
a
mystery to this day.
Was Stradivari
a
genius -or
did he set such high standards for his work that the results dwarfed the efforts of all his contemporaries and
successors?
Since the early days of high fidelity the name Radio Craftsmen has been synonymous with
the sound of quality." Others have tried to equal their accomplishments but few will pay the price of leader
-
ship...which
is no compromise with quality.
materials and workmanship in
a
A
careful examination of the
Craftsmen unit, beginning with the unique
chrome plated chassis, will show that no compromise has been made in pro
Model CT -2
during the world's finest high fidelity equipment.
Ask for
a
-
demonstration
of the Craftsmen high fidelity components at your dealer now. Or write for your free, illustrated catalog.
RADIO
R A FT S M
INC.
a
subsidiary of PRECISION RADIATION INSTRUMENTS
4223 West Jefferson Boulevard, Los Angeles 16, California
THE NEW CRAFTSMEN
MODEL CT -2 AM-FM TUNER FEATURES "MAGNA RAY" TUNING -ANOTHER CRAFTSMEN FIRST
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3.52%
WON'T CARE
.97 °0
WILL ASK FOR A
REFUND OF $15.00
and
they'll
get
it
BUT...
The announcement on the reverse
side of this flap is of importance to
96.48%
of AUDIO subscribers
AUDIO
wishes to thank
BRITISH INDUSTRIES CORPORATION
for relinquishing this
space
for
one
month to make room for this
important announcement
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of AUDIO
subscribers are not yet
Ale
Sut icribero
but many have suggested
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3.52%
are already
elle .SutJcriher.
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subscribed at
the $50.00 rate, and they will
receive a $15.00 refund.
When the original announcement
was made in 1953, the yearly rate
was $3.00. Increased production costs
made it necessary to increase the yearly
rate to $4.00, and shortly thereafter
the LIFE SUBSCRIPTION was increased
to $50.00
BUT NOW -until
April 15, 1956
fou
can become a
oCte Sub.icriber
at the special rate of
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Tear out the subscription card at the
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envelope with your check or money order
and mail NOW! Your subscription will
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a Life Subscription when the present term
expires. But, DO IT NOW! Your subscription
must be postmarked not later than April 15, 1956.
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MARCH, 1956
VOL. 40, No. 3
Successor to RADIO, Est. 1917.
AU D Io
q NCINEERINC
511'SIC SOUND REPRORCCTION
C. G. McProud, Editor and Publisher
Henry A. Schober, Business Manager
Harrie K. Richardson, Associate Editor
Lewis C. Stone, Associate Editor
Emery Justus, Canadian Editor
Florence Rowland, Production Manager
Edgar E. Newman, Circulation Director
ttUNIDYNES"
Sanford L. Cahn, Advertising Director
-
esa
are the only small size,
all- purpose moving coil
Dynamic Microphones that
reduce the pickup of
random noise energy by 67 %.
Special Representative
H. Thorpe Covington,
7530 Sheridan Road, Chicago 30, Ill.
Mid West Representative
Sanford R. Cowan, 67 West 44th St.,
New York 36, N. Y.
-
The Unidynes, 55s and
-
556s, simplify P. A.
installation
enhance
your reputation
insure
customer satisfaction by
eliminating or reducing
callbacks due to critical
gain control settings
West Coast Representatives
James C. Galloway and J. W. Harbison,
6535 Wilshire Boulevard, Los Angeles 48, Cali!.
...
...
-
CONTENTS
Audio Patents
Letters
Coming Events
About Music-Harold Lawrence
Editor's Report
How Loud is Silence?- Charles E. White
The Artistic Integrity of the Record-Otto Mayer -Serra
At Home with Audio -Lewis C. Stone
Transformer Design for "Zero" Impedenee Amplifiers -R. N. Grossner
Audioelinic-Joseph Giovanelli
Preamplifiers and Control Units-SOUND, Chap. 6 -Edgar M. Villchur
Equipment Report -10 -Watt Munston Amplifier-Miratwin MST -2D
Magnetic Pickup Cartridge-H. H. Scott 311 FM Tuner
Jazz by Jean -Jean Shepherd
Record Revue- Edward Tatnall Canby
New Literature
New Products
Audio ETC-Edward Tatnall Canby
Industry People
Advertising Indes
2
often necessary when
conventional microphones
4
have been installed.
6
No wonder the Unidynes
are used the World over
more than any other
8
14
17
20
22
27
32
36
40
48
50
55
56
60
70
72
(title registered U. S. Pat. OR.) is published monthly by Radio Magazines, Inc., Henry A. Schober,
President;
McProud, Secretary, Executive and Editorial Offices. 204 Front St., Mineola, N. Y. Subscription
rates-U. S.,
Possessions, Canada and Mexico, $4.00 for one year, $7.00 for two years all other countries. $5.00
per
year.
Single
copies Soc. Printed in C. S. A. at Lancaster. Pa. All rights reserved. Entire contenta copyright 1956
by Radio Magazines,
Inc. Entered as Second Class Metter February 9, 1950 at the Post Office, Lancaster, Pa. under the Act
of March 3, 1879.
-
microphones -for
finest quality
public address
theater stage
sound systems
professional
recording
remote
broadcasting.
...
...
...
AUDIO
C. O.
RADIO MAGAZINES, INC., P. O. Box 629, MINEOLA, N. Y.
AUDIO
SHURE BROTHERS,
Inc.
Microphones and Acoustic Devices
225 W. Huron St., Chicago 10, Illinois
Cable Address: SHUREMICRO
MARCH, 1956
1
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AUDIO PATENTS
Pr
TUBELESS
RICHARD
H.
DORF*
AUDIO
COMPENSATION
only 14 db!
insertion loss!
The Model
izer
4201 Program Equal-
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of sound recording and broadcast
channels. High and low frequencies
may be boosted or attenuated while
the program is in progress with negligible effect on volume levels. It may be
switched in or out instantaneously to
permit compensation at predetermined
portions of the program. This feature
is
especially useful in tape dubbing
work.
®
ó
Model 4201, Progrom Equalizer
FEATURES:
Equalization and attenuation in accurately calibrated 2 db. steps at 40,
100, 3000, 4000 and 10,000 cycles.
Insertion Loss: Fixed at 14 db. with
switch
"in"
or
"out."
Impedance: 500/600 ohms.
Low Hum Pickup: May be used in mod-
erately low-level channels.
send for Bulletin E for complete data
;195.00
Net Price
F.O. B. North Hollywood
Modrl .1201 Program Equalizer is also
available for the custom builder in kit
form with complete wiring instructions.
Send for Bulletin TB-4.
Representatives in
Principal Cities
HYCOR
Division of
International Resistance Company
12970 Bradley Avenue,
Sylmar 3, Calif.
OR SO AGO I telephoned Mr.
Henry E. Sharpe to get some details on a new patent which had been
kIONTR
issued to him and looked interesting for
this department. I didn't know Mr.
Sharpe,t but he turned out to be not only
a patent attorney but also Vice -Chairman
of the Committee on Public Relations of
the New York Patent Law Association.
Our conversation turned to patent matters
in general and it developed that Mr.
Sharpe is knee deep in a campaign to help
the Patent Office recruit new patent examiners. It appears that the shortage of
them is largely responsible for the fact
that it takes three years or more for a
patent application to be processed. Mr.
Sharpe whetted my interest in this subject
and I pass on some of the information to
you. Many AUDIO readers are undoubtedly
eligible for examiner positions and may be
interested; for those who are not, I purvey
herewith in addition a little background
on the way the P. O. runs, which should be
of interest because of the very strong influence of that government activity on
technological progress in this country.
To begin with the want ad, you, too, can
be a patent examiner if you have a college
degree (even a recent one) (a) in any
field of engineering or applied science, or
(b) with a chemistry major including 26
hours in chemistry, or (e) with a physics
major and 21 semester hours in physics, or
(d) with any other major that included
either 40 combined semester hours in engineering, chemistry or physics, or 28 combined semester hours in chemistry and
physics.
Pay begins at $4345 a year and after
six months you rise to $4930. Merit raises
after another year and another 18 months
can be to $5440 and $6390 yearly, respectively. Two and a half to three years later
if you merit it, you can get up to $7570.
Further advancement, says the Patent Office, can take you up to $13,760 a year.
You get 13 working days of vacation each
of the first three years, 20 working days
after that, and if you reach the 15 -year
mark, 26 working days are yours to spend
in pleasurable pursuits every summer. If
you are after an advanced degree, the authorities point out that there are seven
schools in Washington which give suitable
evening courses.
There is no examination for the job if
you fulfill any of the above requirements.
Just apply to the Commissioner of Patents,
Washington 25, D. C., and presumably if
your qualifications look interesting, you
will be sent instructions.
Some idea of the need for new examiners
(300 are wanted in 1956) can be had from
the fact that as of last April there were
138,000 applications in the Office awaiting
action by examiners, as well as 80,000 waiting for responses from applicants. This
backlog, which exists all the time, is why
applicants have to wait many months for
each Office action and have to suffer the
results of incomplete protection on their
inventions and developments.
`Audio Consultant, 255 W. 84th St.,
New York 24, N. Y.
s Nor, I think, did he know me. Take
that -and that, ego!
Progress of an Application
When you want to get a patent on an
invention, you or your attorney must file
an application in prescribed form, which
includes a complete description of the invention, one or more drawings where necessary, an oath to the effect that you are
the sole and original inventor, and so on,
and the fee.
After routine processing, your papers
reach an examiner, whichever one it may
be assigned to within the one of the 66
Divisions into which your invention is classified. The examiner studies your application and claims, searches U. S. and foreign
patents, and the literature to see if he can
find any evidence that someone has invented
"your" gadget first or has come close
enough to rule you out as the first inventor. The usual result of this is a socalled Patent Office "action" citing prior
art to show why at least some and perhaps
all of your claims cannot be allowed. This
is transmitted to your attorney.
Usually, you (if you are not a guardhouse lawyer) immediately concede that
the examiner was right and are ready to
drop the whole thing. However, your attorney is not so ready to call it quits, for
he knows that between the black and the
white there is gray-and furthermore, an
examiner can be entirely mistaken and
doesn't mind being told so- politely. So,
sometime within six months after receipt
of the action, he drafts a response which
may point out where the examiner is wrong
and why certain of the rejected claims
should be allowed, or he may redraft
claims to eliminate technical objections, or
he may add new claims, taking care that
nothing added strays from the invention as
originally described. Again the examiner
considers the application, this time as
amended. He may accept and allow some
of the changed or added claims, or he may
again disallow some or all claims, depending on what he believes to be the proper
interpretation of such prior art as he has
found. This interchange between attorney
and examiner can go on indefinitely, theoretically, until both are satisfied. In fact,
it is rare that more than three actions are
taken by the examiner, after which the
patent is either issued with the unrejected
claims or is abandoned.
At least one fly can invade the ointment
during this processing period -an interference. This is declared when two applications in process at the same time are
thought to conflict. It is then up to the
two applicants to prove priority of invention. Interferences can be declared only
while both applications are in process; an
application which has resulted in an issued
patent is considered to be anticipation of
any application granted and cannot be attacked except through the courts in an infringement proceeding. So the longer your
application takes to become a patent, the
longer you are open to interferences from
others who may have bad the same idea
as you a little later. And the fewer exam-
iners on the job, the longer your application takes.
You may, of course, disagree with the
examiner's final rejections of some or all
(Continued on page 65)
AUDIO
2
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
now presents its new
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Turntable
t'E;:IT URES :
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O
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TURRET- DRIVE
MECHANISM: Large, true pulleys
PERFECTED
actuate oversized live rubber Interwheel, whi:h is mounted on boll
bearings and retracts upon shutoff.
OVARIABLE SPEED CONTROL- Simple, foolproof
SHUTOFF BRAKE: Sect,. Ires tom table revolutions when unit Is
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eddy current broke permits
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etal dh:
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Tone_Stote
LETTERS
Biflex Speakers
SIR:
NGSOL
In his letter published in AUDIO of January, 1956, Mr. H. A.
Hartley criticizes my article in the November issue describing
Biflex loudspeakers, and claims that the system of cone compliance described by me is his invention dating back to 1938.
United States Patent No. 1,846,937 issued to A. V. Bedford in
1932 (six years before Mr. Hartley 's invention date) discloses
as Claim #1: "A diaphragm comprising a plurality of sections
of successively larger area, and coupling means for said sections comprising damping members connected to adjacent sections." Mid -compliances and the use of viscous materials are
disclosed in United States Patent No. 1,876,831 issued in 1932
and No. 2,071,829 issued in 1937. I believe these patents fully
describe the systems that Mr. Hartley claims to have invented
in 1938. Our study of the U. S. patent structure did not reveal
inventions in this field by Mr. Hartley.
The refinements of application and design engineering using
these compliance principles as an extension of the art was discussed in my article. The analog which appeared in this article
was simplified for the purpose of explaining in simple, basic
terms the actions of the various components of the moving system of the Biflex loudspeaker. The text covered the various elements, but although Mr. Hartley finds fault with the mathematics, actually no mathematical analysis whatever was given.
More important, he apparently missed the explanation which
treats the purpose of the mechanical resistance on the edge
compliance of the cone (EM, and Ce). The addition of what
he refers to as "goo" on the edge compliance does not perceptibly change the resonant frequency. As was explained in
my article, the only function of RM which is the mechanical
resistance termination in the form of a viscous solid layer, is
to absorb the energy travelling in the cone and prevent its reflection. When such reflections are permitted to occur, serious
irregularities will result due to standing waves in the cone.
Edge compliance damping has been used by many manufacturers in the United States for at least the past decade to prevent this condition. This important feature of design seems to
have been overlooked by Hartley, as has the need for protecting
the magnetic gap and voice coil from ferrous particles and dust.
The voice -coil compliance suggested by Mr. Hartley for improved high-frequency response is a well known expedient which
proved unnecessary in the Biflex design, for the benefits received therefrom would, in my opinion, have been more than
offset by loss in efficiency and other considerations.
The wide acceptance of the new Biflex line of Altec Lansing
speakers by the public and praise from critical listeners seem
ample testimony for the soundness of design and exceptional
quality of these speakers.
HI -FI TUBES
For Equipment deserving
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Premium performance to satisfy the most
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12AX7 TWIN TRIODE VOLTAGE AMPLIFIER
picks up low level signals without Introducing hum.
5881 BEAM POWER AMPLIFIER
provides the ultimate in reliability where the 6L6
is normally called for.
6550
BEAM POWER AMPLIFIER
first in the 100 watt power range designed
specifically for audio service.
ALEXIS BADMAIEFF,
Altec Lansing Corporation,
9356 Santa Monica Blvd.,
Beverly Hills, California.
Gremlins Again
Sm:
Several significant errors appear in the schematic wiring
diagrams presented in my article "High -Quality Dual Channel
Amplifier " in the January issue. In the low -pass section of the
high- impedance dividing network, (Fig. 2), the final capacitor
in the three -section R -C network is .00025 instead of .0025. In
the power amplifier the portion of the cathode resistor of the
6J7 tube which is not bypassed (Fig. 3) is 33 ohms rather than
33,000 ohms. The input coupling capacitor is 0.1 pf. These
errors do not appear in the original circuit diagrams supplied.
It might be worth mentioning that the power amplifier (Fig.
3) is easily modified to accommodate type 6550 tubes. The same
output transformer is ideally suited to this purpose. The power
output is doubled for the same distortion. Circuit changes inelude employment of a different cathode bias resistor and a
screen voltage dividing network with a bypass capacitor, and
increasing the power supply voltage by using a capacitor input
filter (Fig. 4).
TUNO -SOL ELECTRIC lac.
Newark 4, N. J.
Soles Offices. Atlanta. Colimbos. Delver Lity, Dallas.
Denver, Detroit. Melrose Part (111.1, Newark, Seattle.
CHARLES W. HARRISON, JR.
Commander, USN,
1401 N. Pocomoke St.,
Arlington 5, Virginia.
(Several readers noticed these errors. ED.)
Lr
Miniature
Lamps
Sealed
Beam
Meadlemps
senas
Flashers
Medro And
TV Tuses
Aluminized
Picture Trews
Span'
Purpose
Tueca
SendcaMucten
..
Sm:
An unfortunate draftsman's error in my article "Transistor
Tips and Techniques" in the February issue rendered Fig. 5
AUDIO
4
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
"Scotch" Magnetic Tape solos
in "The Benny Goodman Story"
Star
of the Universal-International Technicolor
IT'S STEVE ALLEN
Film and the NBC -TV SHOW "TONIGHT" -Steve Allen in the role
not Benny Goodman you'll
see in the new Universal -International Techni-
color Film, "The Benny Goodman Story". But
the music you'll hear is by the "King of Swing"
himself -as originally recorded for this picture
on "SCOTCH" Magnetic Recording Tape.
Actually, "SCOTCH" Magnetic Tape plays
two important roles in the new U -I film. Not
only were the original Goodman performances
recorded on "SCOTCH" Brand, but the entire
finished sound track as well. The brilliant results
make "The Benny Goodman Story" an audio
as well as visual success!
of Benny Goodman
-
In film studios, in business and in the home
wherever flawless recording results are required,
"SCOTCH" Magnetic Tapes take top honors.
Produced by the world's largest manufacturer
of coated products, "SCOTCH" Magnetic Tapes
enjoy an established world -wide reputation for
unsurpassed fidelity,
reel -to-reel uniform-
ity and technical
superiority. Put these
tapes to the test by
using them on your
own machine. .. soon
!
The term "SCOTCH" and the plaid design are registered trademarks for Magnetic Tape made in U.S.A. by MINNESOTA MINING
AND MFG. CO., St. Paul 6, Minn. Export Sales Office: 99 Park Avenue, New York 16, N.Y.
AUDIO
MARCH, 1956
5
www.americanradiohistory.com
AmericanRadioHistory.Com
H
F
U G
A L
H E S
C O N
Research
and Development
at Tucson
meaningless. First, the two points B and S
were interchanged. Second, the horizontal
axis should have been labeled COLLECTOR
VOLTAGE instead of Supply Voltage, and
the vertical axis should have been labeled
COLLECTOR CURRENT instead of Collector
Voltage.
This should clear up any confusion, and
should allow readers to observe the similarities between the transistor characteristic
curve families and those for vacuum tubes.
PAUL PENFIELD, JR.,
752 Lakeside,
Birmingham, Michigan.
(We know of another one, too. On the
cover of the February issue, the word DIRECTION should have appeared instead of
the word Distortion alongside the diagram
of the magnetic pickup. En.)
The Hughes Research and Development Laboratories
have now been extended to Tucson, Arizona,
where the deadly air-to -air Falcon is
presently being produced for the U.S.
Air Force
and Canadian continental defense interceptors.
This is in line with a long -range program
that includes application of the Hughes Falcon to more
and nive types of military aircraft.
ENGINEERS
March 19 -22 -IRE National Convention.
Waldorf -Astoria Hotel and Kingsbridge
Armory, New York.
PHYSICISTS
April 10 -12 -Radio Electronic Component
New positions are being created in fields of
specialization covering the complete range
of structural, hydraulic, electronic, and
electromechanical engineering. Experimental,
analytical, or design abilities will be
required of those who work in these areas.
April 13 -15 -The London Audio Fair 1956.
Washington Hotel, Curzon St., London,
England.
Scientific Staff Relations
April 23- 24-New England Radio-Electronics Meeting, "Stocktaking of Electronic Progress." Sheraton -Plaza Hotel,
H
u
Manufacturers Federation Show, Grosvenor House, London, England.
H
E S
RESEARCH AND DEVELOPMENT LABORATORIES
TUCSON, ARIZONA
April 16, 18,
19-Broadcast
Engineering
Conference, in conjunction with the 34th
annual Convention of the National Association of Radio and Television Broadcasters. Conrad Hilton Hotel, Chicago.
Boston, Mass.
April 29 May 4 -79th Convention of the
Society of Motion Picture and Television
Engineers, hotel Statler, New York
City.
6-
April 23 May
British Industries Fair.
Earls' Court, London, England.
May 1 -3-Joint Electronic Components
Conference, I.R.E., National Bureau of
Standards, Washington, D. C.
May 21-24- Electronic Parts Distributors
Show. Conrad Hilton Hotel, Chicago, Ill.
June 17-23--Second International Congress
on Acoustics. Registration at Mass. Inst.
of Technology, Cambridge, Mass.
June 18- 29-Special Summer Program in
Switching Circuits, M. I. T., Cambridge,
Mass.
Aug. 21- 24- WESCON, I.R.E. Convention
and West Coast Electronic Manufacturers Association show, Pan Pacific Auditorium, Los Angeles, Calif.
Oct. 17- 21- Second "Feria de Alta Fidelidad," Mexico, D. F. Sponsored by Aso ciacion Mexicana de Impulsores de Alta
Fidelidad. For information, write Mario
R. Aguilar, Lopez 43, Mexico 1, D.F.
AUDIO
6
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AmericanRadioHistory.Com
MARCH, 1956
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There is no finer, smoother- running or easier -to- operate
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AmericanRadioHistory.Com
TOP PERFORMANCE
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FULL RESONANCE
TWIN -CONE
SPEAKERS
HAROLD LAWRENCE
Handel With Care
NO QUESTION that Bach and
Handel were the dominant figures in the
late Baroque era. Yet, in the representation given the two composers in concerta, publications and recordings, there
is a staggering preponderance in favor of
THERE IS
Philips of the Netherlands precision built full resonance speakers are a special twin -cone design which provide
energy transmission almost independent of frequency. Sound pressure within an angle of 90° does not vary by
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is responsible for the excellent spatial
distribution of the acoustic energy even
at highest frequencies.
This sample characteristic curve has
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fundamental resonance of the speaker
with
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Bach.
Most of Bach 's works are readily available in many editions. In the concert hall,
no organ recital series would be complete
without the inclusion of at least one entire
program devoted to Bach 's compositions,
not to mention a complete Bach cycle.
Chamber orchestras regularly perform the
Brandenburg Concertos, the Suites, and
the Violin and Clavier Concertos. Pianists
and harpsichordists play the Partitas, English and French Suites, the Italian Concerto, the Toccatas and, of course, that keyboard bible, The Well- Tempered Clavier.
No violinist worth his rosin would dream of
omitting the Violin Sonatas (accompanied
and unaccompanied) from his repertoire.
The same can be said for the Cello Sonatas.
And in churches of many landa, the Passions and the Mass in B Minor are familiar
works.
This was not always the case. For nearly
a century after his death, Bach was a dim
figure out of the past in the eyes of all but
a few musicians. One of these, Felix Mendelssohn, took more than a private interest
in Bach's music and nearly ainglehandedly
brought about a Bach renaissance that
eventually led to a full recognition of the
composer's genius.
Recognition came to Handel early in
life and lasted (particularly in England)
until the present. But it was of a static
nature. While Bach 's first nineteenth-century champion, Mendelssohn, was busy
reviving such masterpieces as the St. Matthew Passion, and later musicians and
composers extended the public's appreciation to include the great scope of Bach's
over -all production, nothing of the kind
happened to Handel's music.
* 26 West
N. Y.
Caricature
Ninth Street, New York
11,
After nearly 200 years, the picture of
George Frederick Handel (1685 -1759) is
still incomplete. He is known to music
lovers by a limited number of works, and
most of these in "arranged" forms. His
arrangers have been nearly all conductors.
Sir Hamilton Harty was responsible for
the Suites from Water Music and Royal
Firework+s; Sir Henry J. Wood modernized
the Organ Concerto No. 9; Sir Thomas
Beecham "suitened" The Faithful Shep.
herd; and Eugene Ormandy gave the Philadelphia Orchestra treatment to the Organ
Concerto in D. Of original Handel, the
most frequently -heard works are the Concerti Grossi, Op. 6, the Violin Sonata No.
4, the movement of the Clavier Suite in E
subtitled, "The Harmonious Blacksmith,"
and some of the organ concertos. Apart
from regular performances of Messiah and
occasional hearings of Judas Maccabaeus.
Israel in Egypt and a few other operas and
oratorios (Xerxes, Handel's only comic
opera and the setting for the famous
Largo, was recently given a halfhearted
revival in New York), the dramatic Handel
is virtually unknown.
The curious fact is that while practically
every note of Messiah is familiar to music
lovers everywhere, no more than a few
isolated arias and choruses remain from
Where'er
other operas and oratorios:
you walk" ( Semele), "Alma mia" (Floridante), "See the Conquering Hero
"
Comes" (Judas Maccabaeus)
are
some
examples.
What, then, accounts for the almost
universal neglect of the rest of Handel's
the hundred cantatas, the
vast output
dozens of unplayed operas and oratorios,
and the large body of vocal, chamber, instrumental and church music? Have they
simply failed to withstand the ravages of
time or, as one critic put it, "Is Handel,
...
like early nineteenth century silver, only
second -hand and not antique?"
The answer has been offered that since
his works were seldom performed more
than once or twice during his lifetime,
they were therefore quickly forgotten. By
-Bettman Archive
of
three
famous
singers of the day
in a scene from
Handel's
"Julius
(c.
opera,
Caesar"
1724).
From
left to right: Caesar
(Berenstadt),
Cleopatra (C u z zoni), and Marc
Antony
(Sene-
sino).
Send to Dept.
A3 today for more details
North American Philips Co., Inc.
100 E. 42nd S
New York 17, N. Y.
AUDIO
8
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
?E1ECTRaN
The British Electronics Industry is making
giant strides with new developments in a
variety of fields. Mullard tubes are an
important contribution to this progress.
For medium power equipments
British high fidelity experts choose the
The Mullard range of high fidelity tubes
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This is because many years of research and development have been spent in producing a range that will
meet the requirements of high fidelity sound reproduction in all respects. Take the Mullard EL84 for
example. A pair of these tubes provide a power output of 10W at a distortion level of less than %.
Furthermore, their transconductance of over 1,000
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The EL84 may be used for higher powers too. Two
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7W at an overall distortion of 4 %.
At maximum ratings one EL84 has a plate dissipation
of 2W and gives an output of 5 -6W for an input
signal of less than 5V r.m.s.
Supplies of the EL84 for replacement in British
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mentioned below.
1
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Principal Ratings
Heater
6.3V, 0.76A
300V
Max. plate voltage
Max. plate dissipation
12W
Max. screen voltage
300V
Max. screen dissipation (max. signal)
4W
Max. cathode current
65mA
Base
Small button noval 9 -pin
-
Supplies available from:
In the U.S.A. International Electronics Corporation,
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In Canada
Rogers Majestic Electronics Limited,
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Mullard'
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AUDIO
gip
MARCH, 1956
9
www.americanradiohistory.com
AmericanRadioHistory.Com
the same token, not many of Bach 's works
were repeated in public performance during his day, yet they are standard fare today. And, as for Schubert, some of that
composer
symphonies were not played
until years after he died: the Symphony
in C ( "Great ") received its premiere in
1839 and the "Unfinished" in 1865, eleven
and thirty -seven years following his death!
In the case of Handel's operas and oratorios (the most flagrant omissions in the
repertoire), there is a more plausible ex-
's
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planation.
When Handel came to London in 1710,
opera was enjoying a great vogue. The
accent was then on spectacles and star performers. Thus, in Rinaldo, Handel's English operatic debut, the sets included a
"Chariot drawn by two Dragons," a
"black cloud
fill'd with dreadful Monsters spitting Fire and Smoke," '' Waterfalls
Thunder, Lightning, and amazing noises," and a "delightful Grove in
which the Birds are heard to sing, and
seen flying up and down among the Trees."
Reviewing a performance of Rinaldo, Sir
Richard Steele in the "Spectator" had
some comments to make about the Birds:
"The Sparrows and Chaffinches at the HayMarket fly as yet very irregularly over
the Stage ; and instead of perching on the
Trees and performing their Parts, these
young Actors either get into the Galleries
or put out the Candles...."
In the face of all these diversions, nobody paid much attention to the libretto.
Besides, it was in a foreign language which
the average nobleman could not understand. But what did that matter when the
cast included three of the finest Italian
singers of the day! To these ingredients
was added the fresh, vigorous spirit of
Handel's music. Result: Rinaldo was an
immediate success.
Operatic life in early Hanoverian England was strictly an offshoot of the continent-a copy of the Italian original, and
a poor copy at that. Insipid libretti that
passed muster on the boards of the Hay
Market would have been hissed off the
stage in Milan and Florence by a comprehending audience. While it was true that
Handel later edited the texts of some of
his oratorios, he seldom bothered with the
books of his operas. Unfortunately, there
was no da Ponte to work with in London.
But even a passable libretto was ultimately
at the mercy of an artificial operatic formula that is now thoroughly strange to
...
...
modern ears.
Without the burden of costumes, sets
and inept libretti, Handel's concert oratorios -with their emphasis on large
choral forces-stood more of a chance of
survival than the operas.
For all that, too many critics and conductors overlook a significant fact. During
a period of more than thirty years, Handel
devoted his major creative efforts to operatic writing. While it may be true that,
in terms of artistic entities, these operas
contain obsolete theatrical devices, should
we therefore ignore them all, using only a
few excerpts for "clear- the -throat" purposes in song recitals! Certainly Handel
and we- deserve more than this.
By now the reader is probably under the
impression that a revival of Handel's neglected dramatic music would please the
specialist more than the layman. Maybe
the bits and scraps salvaged from these
works represent all there is of lasting value.
The facts would appear to support such
a contention. After all, didn 't Handel turn
out one opera after another in rapid sue cession! How then could lie have sustained
a high level of inspiration! One instance
is all that is needed to demolish this
(Continued on page 64)
-
AUDIO
10
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
A high fidelity turntable, like a battleship, must be rugged, heavy, massive
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A turntable and motorboard assembly that is 10 times the mass of the
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For the gentle touch, Gray's floating action, Viscous Damped Tone Arm, and
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Be assured you
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AUDIO
MARCH, 1956
11
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AmericanRadioHistory.Com
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AmericanRadioHistory.Com
Y.
U.S.A. Cables: Arlab
AND OTHER ELECTRO- ACOUSTIC PRODUCTS
EDITOR'S REPORT
in which Jean Shepherd discusses a
form of music which has as dedicated a following as
the "classics "; and the "Be Your Own Record Critic"
gimmick wherein you may acquire some LP records for
writing your own criticism on one of them which will
be selected each month by Edward Tatnall Canby. The
former is on page 46, the latter on page 50.
Jean Shepherd, our newest acquisition as a contributor, is heard regularly on the air over WOR,
New York, at the unlikely hours of 1 : 00 to 5 : 30
a.m. We think he talks about jazz in an interesting
manner, and our own opinion of his brand of humor
was substantiated in an article by Dr. Howard Decker
in the November 28, 1955, issue of The New Republic.
Dr. Decker claims that a new type of humor has developed on the radio over the past five years, one that is
highly personal and which depends on humor of viewpoint rather than upon the joke or situation. Jean was
listed among the top five humorists-as distinguished
from comedians -on the radio. We commend his column to you, and suggest that if you live close enough
to hear WOR you might derive a lot of entertainment
from his droll wit.
JAZZ BY JEAN,
SUCCESSFUL L. A. HI -FI SHOW
that have been
held throughout the country have been adjudged successful, it has become increasingly
apparent that when an admission fee is charged, the
quality of the attendance is considerably improved
over that at the "free" shows. Whether this can be
attributed to the possibility that people will place no
greater value on a product than do those who are offering the product-and this assumes that the privilege
of attending a show is, in fact, a "product " -or
whether it just reduces the freeloaders who will go
anywhere so long as it is does not cost them anything,
WRILE MOST OF THE AUDIO SHOWS
still awaits determination.
The fact remains, however, that wherever an admission fee has been charged the people who come show a
greater interest in the products offered, are more zealous in their desire to see everything there is to see, and
are universally more courteous in their treatment of
other visitors and the people who are manning the exhibits.
The first show at which an admission fee was charged
city where there was no
was in Toronto last April
previous experience with an audio show which could
serve as a precedent. Toronto is a large city, but it
does not compare in population to either New York or
Los Angeles, and some exhibitors blamed the 5Qy fee
for what they considered a "low" attendance -which
nevertheless reached some 5500. It must also be remembered that this was the first audio show in Toronto
and only the second in Canada.
The Institute of High Fidelity Manufacturers
opened its first industry show in Philadelphia last
November, and an admission fee was again charged.
For Philadelphia, the 17,000 attendance was exceptionally good, and after the show closed exhibitors
were practically unanimous in praising the type of
visitor that came.
Montreal and Toronto both had their second shows
early this year, both charged fees, both had good attendance, and both had people who were seriously interested in audio.
The most recent show in Los Angeles- sponsored
jointly by the I.H.F.M. and the West Coast Electronic
Manufacturers Association -drew an attendance of
nearly 20,000, reliably authenticated by the number
of fifty centses paid in, and all of the people appeared
to have a very real interest in what they came to see.
From the exhibitors' standpoint the show was a huge
-a
success.
With the additional "kitty" to draw from, future
IHFM shows will continue to be successful-not only
in the numbers of people that attend, but also from the
broader angle of spreading the story of hi -fi to more
and more people each year, because the kitty will permit adequate publicity for the shows with the natural
consequence of greater and more valuable attendance.
We are wholeheartedly in favor of continuing the admission fee.
INNOVATIONS
Two new features appear in this month's
issue-
TRUTH IN ADVERTISING-Cont'd.
In November of last year, M. Harvey Gernsbackpresident of Gernsback Publications, Inc., and editorial director of Radio-Electronics -sent a letter to his
magazine's advertisers stating some regulations which
were to go into effect with the beginning of the new
year. Principally, these regulations provided that mail order tube advertisers must state in their advertisements that they warrant the tubes offered to be new
and unused, that they are not mechanical or electrical
rejects, and that they are not washed and /or rebranded. We sincerely approve of Mr. Gernsback's
stand, and commend him for it.
We commend him for two reasons -first, because
we believe that those who buy from mail -order (or any
other) advertising have a right to be protected from
unscrupulous or downright false advertising ; and
second ; because AUDIO has always been conscious of its
obligation to readers with respect to the advertising
pages. Over the past years, we have refused a few ads
-some we have stopped after one appearance, others
after numerous complaints. We do not permit the advertising of prices below the manufacturer's stated
prices except in the case of bona fide closing out sales
or for used equipment ; we do not permit the description of a product in unsupportably enthusiastic terms;
we insist upon knowing who the principal is when the
ad is placed through an agency ; in short, we try to
make sure that the reader ' gets "only the facts,
ma'am."
We think that our advertisers deserve a salute, too,
because we have so rarely found any reason to question
the products that they offer. Naturally, each one believes his products to be the best (if he didn't, he
should set about to improve them so that they were)
and he is entitled to say so. But it is to the everlasting credit of the greatest majority of the hi -fi manufacturers that they do so with fairness and honesty.
AUDIO
14
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
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MARCH, 1956
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PR01U! ATOMS TO
Research at Bell Telephone Laboratories ranges from the ultimate
structure of solids to the radio signals from outer space. Radio interference research created the new
science of radio astronomy; research
in solids produced the transistor and
the Bell Solar Battery.
Despite the diversity of their talents, Bell Laboratories scientists and
engineers have much in common. A
habit of teamwork channels these
talents into great communications
advances. These men have developed
STARS
the world's finest telephone system.
In doing so, many have become leaders in their fields. Opportunities for
achievement await properly qualified
scientists and engineers at Bell Telephone Laboratories.
f¡
Between atoms and stars lie great
areas of effort and achievement in
,,
f
physics, electronics, metallurgy,
chemistry and biology. Mechanical
engineers visualize and design new
devices. Mathematicians foreshadow
new communications techniques.
Models of the atomic patterns in solids
help Bell Laboratories scientists visualize
their electrical behavior.
Directional antenna used by Karl G. Jansky
in discovery of stellar radio signals at Bell
Telephone Laboratories in 1932.
BELL TELEPHONE LABORATORIES
WORLD CENTER OF COMMUNICATIONS RESEARCH
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How Loud is Silence?
Research has determined that the lower limit of our hearing threshold is close to the noise level
generated by the movement of the air molecules. The possibility of reaching this sensitivity appears remote, however, because of the noises continually present within the ear itself.
CHARLES
IN AUDIOLOGY, as in all scientific studies,
a knowledge of measurable limits is
always desirable and, if unknown,
extensive efforts are made to establish
their values. Considerable work has been
done and numerous reports written concerning the maximum limit of sound
tolerated by the human ear. The other
limit, that of the threshold of hearing,
also has received a great deal of attention and the trend in the past twenty
years has been to push back this limit to
lower and lower values. Consequently,
there arises a healthy interest in what
constitutes the theoretical minimum
sound field which might he distinguished
by the ear.
Calculation of Brownian Motion
The ntinitnutn sound field which could
be distinguished by the car is that in-
tensity which just exceeds the Brownian
movement of the particles of air.
Through the work of a number of seientists there are available considerable
data relating to the presence and detection of the absolute minimum field. In
the forefront appear the references to
the theoretical limit of aural acuity as
discussed by Sivian and White' in 1933.
Employed in their dissertation was a
relationship between the energy generated by thermal agitation, or the Johnson effect, and the energy capable of
being propagated, or detected, by a piston source within an infinite baffle, which
is used as an analogy for the ear.
Thermal Energy = 4KTR x df
Received or Propogated
Energy = (SxPt)4xdf
where K is Boltzman's constant,
T is absolute temperature Centigrade,
R is the resistance component
of the impedance across which
is developed thermal agitation,
P1 is the thermal- acoustic pressure,
S is the area over which P, is
developed.
P. O. Box 137, New London, Conn.
Sivian and White, "Minimum audible
sound fields." J. Acous. Soc. Am., 4, pp.
305-307, 1933.
°
'
AUDIO
WHITE
E.
From these relationships is expressed an
equation :
(Sx1'/)2
Rf
-4KTxdf
(1)
where R is denoted as the acoustic radiation resistance at the frequency df. If
S is considered to be a disc, equation .(1)
becomes
(na'Pt)s
4KTxdf
Rf¿f =
(2)
By reference to Rayleigh2, the reaction of air to the displacement of a disc
in an infinite baffle is represented in part
by a frictional force which is proportional to the radius of the disc and the
displacement of the disc surface and inversely proportional to wavelength.
From the equation for this frictional
force, the radiation resistance may be
determined, and when substituted into
equation (2), the thermal acoustic pressure becomes
4KTvc 11
P
J, (2Ka) \
:
( )
Ka
J
where J,(2Ka) is a Bessel function. As
a approaches zero, the original energy
e/At
astuz
equation becomes
Pffx cif =S'KT
frxdf
c
(4)
and the r.m.s. pressure p in any frequency interval (f2-f,) is determined
to be
j;=
-(fz'- f,'`)I'
13nKT
(5)
Herein vas presented for the first time
an approach to the calculation of absolute hearing threshold. Using equation
s
(5) Sivian and White determined the
pressure P to be equal to approximately
-5
5 x 10 microbar for a frequency range
1000 -6000 cps. This level, which is 86
db below one microbar, was felt by
them to be quite close to the minimum
threshold measured in the laboratory,
which is an average of 76 db below one
microbar in the same frequency range.
In 1948, deVries3 approached the
subject from the physioneural viewpoint.
The referenced article dealt with the
minimum perceptible stimulus for vision,
touched on nerve excitation and then
briefly touched upon hearing stimulus.
In the article, deVries stated that the
minimum perceptible stimulus corresponded to the absorption of a single
light quantum by a molecule of visual
purple in each of several retinal rods.
For simplification, he assumed that only
one rod need be excited. This gave an
equation for the number of spontaneous
thermal excitations:
Lord Rayleigh, "Theory of Sound,"
Vol. 2, Sect. 302. Dover, 1945.
(6)
q=
In this equation, E is he energy necessary to decompose a visual purple molecule. The exponent denotes the probability that the essential part of the molecule has a thermal energy greater than
E at a given moment. In every second,
there are 1/s new distributions of energy
and N is the number of sensitive mole cules in one cell. Equation (6) is rewritten as
E = 2.3KT log
(7)
(1q T )
3 deVries, "Minimum perceptible energy of Brownian motion in sensory
process." Nature, Vol. 161, p. 63, Jan.
10, 1948.
Fig. 1. Ratio of in-
tensity of masked
tone, I,,,, to intensity per cycle of
noise, Ir, plotted
against width of
noise
band
in
cycles.
(After
Fletcher,
Revs.
Modern Phys., Vol.
12:
pp.
47 -65,
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17
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From this formula it is possible to
calculate the energy required to excite
the molecules or, more aptly, to set a
minimum boundary for excitation which
will prevent the eye from incurring
spontaneous excitations. This value has
been calculated from experimental anatomical data giving a figure of E = 53KT
for excitation of less than one response
per second. Carrying on this line of
reasoning, deVries then pointed out
that it is possible to calculate the energy
necessary to excite a nerve. He derived
a figure of 25 KT as being the least
figure for which a nerve would be stable.
In deriving a formula for calculating
the pressure of the Brownian movement,
Sivian and White' observed that it was
extremely doubtful that the loudness of
the various frequencies over the band
considered by them would add together
in a simple manner. Continuing in this
vein, deVries stated* that it was more
probable that subliminal excitations
would add only if they corresponded to
the same region of the basilar membrane.
Using this reasoning, he selected a band
width of 400 cycles at a frequency of
2000 cps and calculated the Brownian
movement to be equal to 4.8 x 10 - 13 erg/
sec or an equivalent energy of 0.4 x 4.8 x
10-13 erg,
(1.9 x 10"13 erg). Compared
with the standard minimum audible
energy threshold at the eardrum of
2A x 10 -1° erg, the figure obtained by
deVries is approximately - 31.0 db.
Here it should be noted that the use
of a band width of 400 cycles by deVries
was based upon the masking studies of
Wegel and Lane as reported in the
Physics Review, Volume 23, p. 266, 1924.
Since this report, considerable experimentation has been carried out to determine the critical bands of frequency
which are effective in masking pure tones.
Fletcher' presented the results of his
work on this subject in the form of a
graph, Fig. 1. This graph is a plot of the
ratio of the intensities of the tone under
and the intensity of the
observation
noise band It versus the width of the
noise band in cycles. The parameters are
the frequencies of the pure tones employed in the study.
It will be noted that for a particular
test frequency, the ratio of Im/Il increases with increase in band width until
the band width reaches a value beyond
which no effective increase in the ratio
of Im /ff is required. This value is represented on the figure by the intersection
of the horizontal line pertaining to the
definite frequency with the sloping line
originating at 30,30.
Reference to the figure gives a band
width of 80 cycles for a frequency of
the equation of Sivian and White results in a noise value of 2.48 x 10-u
dynes/cm2 or a level of - 39.3 db relative
to standard threshold of 2.0 x 10.4 dyne/
cm2. These calculations are repeated for
enough points to give the curve (F) in
Fig. 2.
Inspired by Fletcher's work in developing the subject of critical bands,
Schafer, Gale, Shewmaker and Thompson continued the study' at three test
f requencies -200, 800, and 3200 cps.
Their experiments showed critical band
widths of 65, 65, and 240 cycles at the
three test frequencies respectively. Employing these band widths for computation of the Brownian movement and
extrapolating results in a curve (S)
which very closely approximates curve
(F).
Threshold of Audibility
At this point, consideration should be
given to the value obtained for the intensity of sound at threshold as derived
by a number of experimenters. Greatest
sensitivity obtained by Sivian and White'
for free field conditions was 1.9 x 10-10
erg /cm2/sec at a frequency of 3800 cps.
At 1500 cps, the sensitivity obtained was
7.6 x 10.10 erg/cm2 /sec. Using a figure
of 0.43 cm2 for the area of the ear drum,
the figures obtained may be converted
to energies which are equal to 8.2 x 10-11
erg/sec at 3800 cps and 3.3 x 10-1° erg/
sec at 1500 cps.
deVries, "The minimum audible energy." Acta Oto-Laryngology, Vol. 36,
pp. 230 -235. 1948.
3
"Untersuchungen iiher
Geffcken,
akustische Schwellerwerte." Ann d.
Physik 19, pp. 829 -848, 1934.
T
u Schafer, et al, "Frequency selectivity of the ear as determined by masking
experiments." T. Acons. Soc. Am., Vol.
22, No. 4, pp. 492-3, 1950.
40
I.
deVries, "Brownian movement and
hearing," Physica, Vol. 14, No. 1, pp.
48-60, 1948.
Fletcher, Speech and Hearing, pp.
171 -2. Van Nostrand, 1953.
One other factor affecting the sensitivity of the ear drum needs to be considered- namely, that factor representing the percentage of energy transmitted
to the inner ear. It is considered that approximately 20 per cent of the acoustic
energy presented to the ear drum is reflected at a frequency of 1500 cps." As
a consequence, Siviaiñ and White's data
would give a threshold energy flow of
2.6 x 1.0-10 erg /sec.
In a series of experiments, deVries
founds that duration of the signal determined the minimum audible intensity
of sound. For short signals (0.2 second
or less) the intensity was inversely proportional to the length of signal, indicating that the energy for audibility
was a constant. By comparing with
longer duration signals, he obtained a
factor of 0.4 which he used to convert
data obtained by Sivian and White to
minimum audible energy. Use of this
factor gives the minimum audible energy
at 1500 cps as 7.2 x 10-11 erg for an
average good observer.
Through this same procedure, deVries
converted data" obtained from Geffekens
giving a threshold energy of 0.8 x 10.11
erg at a frequency of 1500 cps for a good
observer. It must be borne in mind that
Geffcken's data were obtained by the
minimum audible pressure method which
he claimed, in this case, to give results
which agree with those of the minimum
1500 cps. Substitution of this value into
L\
o
2.
Relationship between auditory thresholds
calculated
and
moveBrownian
ment of air at
Fig.
27'
C.
E
.i
.
+
o
C
o o
//
S
N
wo o
óO20
CC
a
i/
LEAST EMERY FOR
O O
SINGLE
NERVE
ERGITATIDIy,
AT !SOO+
40
Id. V.lFI
A- WAN B WHITE
B - DAMON B KING
C
-SIVIANBWHITE
-MONAURAL THRESHOLD- M
"
0- BERANEK.041- BINAURAL
A P
M A F
THRESHOLD- M. A.F.
F
- BROWNIAN MOVEMENT -SCHAFER BAND DATA
- BROWNIAN MOVEMENT - FLETCHER BAND DATA
G
-
S
IOO
..
A S
4- BINAIIRALTHRESHOLO -M .A
F
(2 24.2-1942
I0K
IK
FREQUENCY -CYCLES /SECOND
AUDIO
18
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MARCH, 1956
audible method. This agreement of data
is at slight variance with results determined by Munson .9 Of more importance
is the fact that Wever and Lawrence10
indicate that deVries is in error in these
calculations by assuming an area of
0.3 cm2 for the ear drum and a duration
time factor of 0.4. It is their contention
that more correct data would be an area
of 0.43 cm2 and a time factor of 0.2. For
the purpose of continuity in this article,
however, data employed by deVries will
be used to complete the discussion.
Previously, a value of 25KT was presented as the least figure of energy for
which a nerve would be stable. This corresponds to an energy of 4.14 x 10' l'
erg at a temperature of 21° C. Use is
made at this point of the standard
threshold intensity of 10-0 erg/cm2 /sec
which, converted to energy absorbed by
the ear drum per second becomes 2.4 x
1.0-1° erg. By comparison to the standard
reference level, the least required energy
to excite a nerve is - 37.6 db.
The average threshold of hearing obtained by Sivian and White, using the
minimum audible field method, at a
frequency of 1500 cps, was - 3.8 db
relative to standard threshold. The
threshold obtained by Geffeken was
-14.8 db relative to standard threshold.
It is readily apparent that a wide gap
exists between these thresholds and the
threshold of spontaneous excitation of
nerves.
Figure 2 presents part of the threshold data discussed previously in this
paper and illustrates the proximity of
the calculated Brownian movement to
the thresholds as determined by various
experimenters. In order to evaluate the
auditory threshold data more accurately,
the figure not only illustrates the results
of experiments by Sivian and White'
but includes as well, data collated by
Beranek', and experimental data from
Dadson and King.12 Note particularly,
that closest approach of auditory threshold to detection of Brownian movement
is in the frequency range 3000 -5000 cps
and in this range, detection of Brownian
movement is separated from the extrapolated curve derived from Schafer's
data by merely 6 db when compared with
Curve (D). Before assumption is made
that we are poised (audibly) on the
verge of a vast new sound field, it is well
to recognize that Curve (D) is not the
direct result of measured data nor is
° Munson and Wiener, "In search of
the missing 6 db," J. Acous. Soc. Am. 24,
No. 5, pp. 498 -501, 1952.
1° Wever and Lawrence,
Physiological
Acoustics, p. 64. Princeton University
Press, 1954.
11
Beranek, Acoustics, p. 396. McGraw-Hill, 1953.
12 Dadson
and King, "Determination
of normal threshold of hearing. J.
Laryng. and Otol., Vol. 46, No. 8, pp.
366-78, 1952.
AUDIO
this made clear in the caption beneath
the curve as presented in Beranek's book.
A personal communication from Dr.
Beranek states in part "It is very possible that curve No. 3 in my paper is not
a curve that can be actually measured
because it was obtained by the following
process. I took the threshold of hearing
as published by the American Standards
Association and subtracted from it the
difference between the binaural curve
for a sound source in front of the listener and the binaural curve for a number
of sources located randomly in a horizontal plane about the listener's head.
Therefore Curve No. 3 was a derived
curve and not a measured curve."
Under the circumstances, we are restricted to use of the curves (C) and (G),
both of which are substantiated by labo-
ratory data from subjective measurements. Deviation of these curves from
the calculated Brownian movement is
approximately 14.5 db at the closest
proximity, indicating inability to detect the Brownian motion of the air.
A consideration of greater importance,
as concerns Brownian motion in general,
is the Brownian movement of the ear
itself. Generally speaking, the movement
of the air will cause only a part of the
total phenomena ascribed to Brwnian
motion as detected by ear. It is pointed
out by deVries' that the ear drum and
the inner ear may be compared to two
electrical circuits coupled by a transformer. Under conditions of good coupling, there will be correlation between
the Brownian currents in the two circuits. If there is a decrease in the coupling, the correlation between currents
will be smaller but the energies will remain the same. Through this analogy
then, deVries believes that, if Brownian
movement could be heard, it would be
that of the ear itself, not the movement
of the air at the drum. He estimates the
former movement to be 100 times larger
in the frequency range 1000-1500 cps.
From this, we may expect that the ultimate audible threshold will be determined
by the ear's Brownian motion and not
that of the air at the ear drum.
Detectability of Brownian Motion
Data have been presented previously
concerning the estimated requirement for
least energy to excite single nerves. This
value (25KT) has been indicated in
Fig. 2. A question arises immediately
concerning the lack of detection of the
Brownian movement signals by the ear.
This has been examined by deVriesla
and the discussion which follows is based
upon his reasoning.
Minimum audible energy for frequencies between 1000 and 1500 cps is
1a deVries, "Brownian motion of transmission of energy in the cochlea." J.
Acous. Soc. Am., Vol. 23, No. 6, pp.
527 -33, 1952.
MARCH, 1956
12 erg or 200KT.1 From the work
of von Békésy and Wegel and Lane, it
has been established that 60 per cent of
the energy resulting from the presentation of a pure tone at a frequency of
1000 cps causes excitation of a small
length (5.0 mm) of the basilar membrane.
Accordingly, presenting energy to the
ear will cause excitation of approximately 5.0 mm of the basilar membrane
at a frequency of 1500 cps. Such a length
of the membrane will include about 3000
sense cells. Equal distribution of the
original energy at threshold (200KT)
would mean an excitation energy for
each cell of .0018KT. More important,
the damping time of the ear is about .003
second, which means that at any time
an energy of only .0018 x .003 or 5.4 x
10-'KT erg is available to the sense
cell. Such a low value of energy would
preclude firing of the cells unless some
accumulative process was available to
the ear.
Let us assume then, that the ear is
capable of integrating sound over a
period of 0.2 second. The original energy
of 200KT is present for 0.2 second and
distribution among 3000 cells gives an
effective excitation of 0.067KT. This is
the threshold capability of the ear. Then
study the effect of Brownian noise added
to this excitation. Masking experiments
set a band width per cell of approximately 75 cycles at a frequency of 1500
cps. The Brownian noise will correspond
to 75KT /second and in 0.2 second would
be equal to 38KT (it cannot be more or
the sense cells would be active permanently). The fluctuations will be approximately V38KT or 62KT. This signal to -noise ratio of .067/6.2 would effectively prevent detection of the signal
and once again an impasse is reached as
regards the theory of the functioning of
the ear.
These discrepancies of the hearing
theories have pointed to consideration of
theories not affected by the "all or
nothing" nerve firing limitations and
have led to the belief that the action of
the basilar membrane fibers is of a nature other than that previously considered. Consideration is given by deVries" to a new theory which relates
tension of the nerve fibers of the membrane, as affected by motion, to an electrical voltage whose polarity and magnitude are governed directly by the tension forces. Through his theory he explains that the action of the Brownian
motion of a cell would be dissipated over
a comparatively large area by virtue of
a multipled parallel connection of cells,
whereas a displacement of the tectorial
membrane would cause all cells to act
together, giving an in -phase voltage.
This theory, supported in part by some
experiments of von Békésy, may aid in
developing a better comprehension of the
(Continued on page 68)
8 x 10
19
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The Artistic Integrity of the
Record
OTTO MAYER -SERRA
Why shouldn't the ultimate aim of musical performers -solo or group, vocal or instrumental-be to achieve their own kind of fame through recorded performances rather
than through concert hall appearances? Can't records be an end in themselves?
STEADILY Gall \VING ACILIE\'E\IENTS in
the field of recording and reproduction
techniques have created a new reality
of musical performance which has not yet
been grasped or fully understood in its
artistic and sociological significance. The
high -fidelity record should not be judged
by the current criteria derived from the
performance of music in the concert hall,
but we should break away from preconceived ideas of concert performance standards when we move in the field of audio.
It is time to take a new critical attitude
which will allow us to analyze the record
from within its own sphere.
The comparison of the 78 record with
the performance in the concert hall was
unavoidable, as the old technique offered
us a mere suggestion of how music really
could and should sound. The LP record, in
many respects superior to the living performance, makes such a comparison preposterous. After having listened to thousands of records in the last years, it no
longer occurs to us to compare the recorded
sound of au orchestra with its " real"
sound in the concert hall. The current adTILE
vertisements of audio equipment "which
bring you the realism of the concert performance in your own home," strike us as
being beside the point. When recently a
famous conductor declared to us in an
interview that the record is for him "a
kind of photography, which needs, as does
all photographic art, excellent illumination," we realized more than ever the need
for a clarification of concepts. How many
people today owe their musical education
exclusively to recorded music-people who
have never attended a concert performance
or an opera?
The idea that the record is a mere black
and white photograph of a splendid and
colorful reality comes from the long existence of the 78 record, and because of the
serious shortcomings of recording techniques, "canned music" was thought to
be inferior to the fresh product. There is
no reason to approach the LP record of
today in that frame of mind.
The comparison between recorded music
and the photographic reproduction of a
painting is not adequate, because, a piece
of music, if it is not brought to sonorous
reality from its score, has no reality at all.
Music only "lives" when it is played or
sung, and its performance today has the
same reality if its impact upon the public
is made via the concert hall or via the
microphone which transcribes the music
onto a record. In both cases, music has to
be rescued from the dead notes of its score
through the action of a similar physical
process whose basic laws are the same although the media of realization are different. Neither of these two ways of making
music live is perfect, but both give us
specific compensations for their respective
shortcomings.
Live Concert Limitations
The handicaps of the living performance
are many and are very well known: there
may be mistakes in interpretatipn, pianos
may get out of tune during a recital, performers may be at less than their best because of mood or health, the hall may suffer from acoustical imperfections or from
"dead" spots, the public may be noisy
or afflicted with colds and coughs.. . To
these things add the inconvenience of being
obliged on a certain day at a certain hour
to leave your comfortable home and perImps slog through the rain to a cold (or
stuffy) concert hall. Perhaps you had a
very busy and tiring day and might really
prefer to rest on a couch at home and read
a detective story. Furthermore, you may
have to listen to a symphony which bores
you or one performed by an incompetent
(in your opinion) conductor to be able to
hear your favorite violinist or some modern work which may come at the end of the
program.
But, on the other hand, the compensations are many. You get a sound quality
of a different order from that received
from recorded music, and you also get the
OTTO
MAYER -SERRA
Born Barcelona, 1904, from German -Spanish
family. Studied musicology at Berlin, CoIonia, and Greifswald, receiving his Ph.D. in
1929. Became, successively, assistant to Dr.
Hermann Scherchen at the State Radio, Berlin. music critic and teacher in Barcelona.
researcher on Mexican and Latin American
music in Mexico, author of several books,
including the first Dictionary of Latin
American Music. He became a music critic,
and was. for several years, publicity manager of Carlos ChSvez, manager of the
Xalapa Symphony Orchestra. In 1952, he
founded the first record magazine in Spanish, 33 1/3, which carries a regular 24page supplement dedicated to high fidelity.
full impact Of the personal appearance of
the artist. There is the always fascinating
"show" of a big orchestra in full action,
and the general assistance of visual perception which helps us understand how the
artist achieves his technical virtuosity- . .
dazzling octaves, the fairy -like notes of a
.
bouncing bow, or the force and grace of a
conductor's baton. The personal glamor,
showmanship, and stage presence of many
artists add an important element to their
performance. In opera, of course, this is a
substantial part of the whole, when added to
the components of scenery, costumes, and
lighting. And let 's not forget the social compensation of concert and opera-going -the
eagerness of the ladies to show off a beautiful gown and jewels (a very important element in maintaining the interest of our concert life and opera season), the pleasure of
meeting friends during intermission and
talking over with them the latest gossip
and the splendor of the tenor's high C,
and the atmosphere of an auditorium full
of people dedicated to an evening of artistic excitement. Furthermore, there is a
feeling of belonging to a privileged group,
whether you sit with the furred and jeweled ladies in a box, or with the intellectually arrogant students in the gallery.
All this is denied to the record listener.
But he can claim an impressive number of
compensations of his own. He can choose
the right time to hear the right music and
he can listen to it in the intimate surroundings of his home. Instead of being submitted to the effects of mass psychology, he
can listen to the music and to it alone (perhaps with a score in his hands), be can
enjoy it in all its artistic purity without
being in any way distracted by extra musical elements. The most famous artists
and orchestras play for him alone, giving
him a feeling of special privilege, for he can
be utterly close to the music and its greatest performers. The piano is always in tune,
even if he listens to Gieseking or Backhaus
for hours. No wrong notes, no mistakes,
no false entrances; this is music in its
supreme perfection.
The Real Differences
The most important difference between
the live performance and the record is obviously the quality of the sound. The lecture concerts of Gilbert A. Briggs revealed that
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MARCH, 1956
recording and reproduction techniques have
reached such a high standard that -in
spite of their qualitative differences -the
similarity between live sound and recorded
sound is so close that many experienced
listeners could not, by the testimony of
their ears alone, distinguish between recorded music and living music. This means
that we have come to the point where recorded music has reached the development
of its own integrity as a full-fledged means
of making music come alive in its own
right. It is no longer a substitute; it is an
entity.
Each score written by a composer requires its realization by a performer. The
composer always needs an intermediary between the products of his imagination and
the public in order to make himself heard;
this is also the case of the group of composers of the nrnsigae concrète who write
directly for electronic instruments.
In earlier ages of our musical history,
the composer himself was always the performer of his music. With the general
"division of labor" of the 19th century,
the composers and performers split into
two different groups of "specialists." The
composer dedicated himself to creating
his scores and relied on trained instrumental performers or singers to present them.
He used an intermediary who became the
means of transmitting to us the music he
wrote. But the record uses two intermediaries -the performer, and the electronic
process of reproduction.
It has been said that the change in the
technical means of presentation of music
has been to the detriment of the composer,
who wrote his works for live performances
in the concert hall. But during the last
century new technical resources and different media were customarily used in performances of music written for quite different groupings of instruments and sizes
of halls. As early as 1784, a century after
his death, Handers "Messiah" was performed at Westminster Abbey with an
orchestra of 250 players and an enormous
choir, whereas for his first performance of
the work, Handel had only forty instrumentalists and twenty voices at his disposition.
Bach is played on concert grands and
electric organs today, and the modern devices of lighting and scenery at the present
Bayreuth Festivals are very much beyond
Wagner's conception. Mozart's operas are
performed in halls ten times as big as
the theatres he wrote them for. This means
that the original cast, performer, instrument or hall for which the composer wrote
has vanished into oblivion. The record is
only yet another link in the chain of new
material means of performance, and does
not alone establish a radically new principle of the reproduction of a score.
The only measure of faithful performance is that of adherence to the truth of
the score. On this basis, the record generally gives us greater faithfulness than the
living performance.
During a concert, the performer, as we
have seen, is not in complete control of all
the elements involved in order to guarantee
perfection. The final product of a record
is always the result of a tremendous
amount of study, worry, and dedication
to achieve perfection. A careful research
of all the acoustical problems involved is
AUDIO
being carried out (hall or studio characteristics, reverberation, diffusion or reflection
of sound, resonance, phase differences, dynamic values, and so on). Infinite experiments are being made in placing
the musicians and microphones. Every
attempt is made to eleminate the slightest
mistake in interpretation. For the first
time in the history of musical performances, nothing is left to chance: each record is meant to be a definite and perfect
realization of the score, not only in its
artistic meaning, but, also, in all its acoustical implications.
"High Fidelity" Implies Perfection
This should be the real meaning of "high
so-much -abused label
should be much more than a description
of design qualifications or recording techniques. Actually it implies a new meaning
-that of sound production in the spirit
of utter faithfulness to the score in all its
aspects to an extent no composer had ever
dreamed to be possible. During the last
decades, the much discussed "fidelity" to
the scores of composers, championed by
men like Mahler and Toscanini, meant only
the exact realization of every detail of the
score as written down by the composer.
Today real "high fidelity" is a great deal
more: the performer and the artistic director of a recording are constantly checking
over the complete realization of the score
and the exactitude of its musical and dynamic values, but also, working with the
sound engineer, the perfect acoustical balance with all its implications from the
point of view of the listener -something
which the conductor in the concert hall,
standing as close as he does to his orchestra, can seldom achieve. Musicians like Hermann Scherchen claim the necessity of recording each composer's works within a
specific sound atmosphere, according to the
style of each work. Some of the most alert
fidelity." This now
artists even go so far as to try to develop
a specific recording style, which might be
of the greatest importance for the future
of the LP record, and might reflect upon
concert -hall performances in the sane way
in which the development of the cinema
and television have affected the stage.
Therefore an acoustical clarity and balance is reached on the record which permits us to hear details frequently lost in
the concert ball. Although the power output of home music is infinitely smaller
and the whole impact is received from only
one single source (or from two in stereophonic reproduction), our ears quickly get
used to the different sound level and quality, and we have no difficulty in identifying
the truth of a reproduction as much as the
definition of details -solo passages, both
instrumental and vocal, polyphonic texture, rhythmic and accompanying figures,
balance of dynamic values, and so on.
Although pleasure in the sound qualities
themselves afforded by a good equipment
has won many friends to the enjoyment of
music, "high fidelity" in its broadest sense
means a revaluation of the artistic content
of a composition. Hi -fi in the current sense
has no artistic value by itself. It gives only
limited pleasure in its sonorous virtuosity,
much as a pianist gives pleasure through
the agility of his fingers. But, as in all
MARCH, 1956
virtuosity, it accomplishes its whole reason
for being only if it is put to the services
of art. Many outstanding "hi -fi" recordings, with mediocre performances, show
us the danger of this new road opened up
to us by electronic achievement.
Fame Through Records
The new world of the record (or the
tape) has reached its autonomy, although
many of its problems are still submitted
to renewed exploration and solution. Many
artists became famous recording artists
who had never achieved fame through personal appearances. There are wonderful
conductors and singers on records-phonogenic artists, as Igor Markévitch calls them
-who are failures in the concert hall, and
others -Maria Callas, to name only one
famous example -who seldom give us the
emotion on a record which they are able
to project from a stage.
In a recent interesting article in the
Saturday Review, in which Irving Bolodin
spoke of the disappointment to the public
of certain famous recording artists when
they were heard in person, be stated:
"It may be that the end of the film
actor's purpose is to make films, whereas
the end of the record performer 's purpose
is to make his name known in the concert
hall or opera theatre. Thus, the film is an
entity in itself, whereas the record is but
an intermediate step to the point of true
celebrity."
Why an intermediate step? If we admit
that true celebrity can be reached in films
by an actor who has never appeared on
Broadway, why not admit that true celebrity can be reached by an artist who has
never been applauded in Carnegie Hallt
We firmly believe that the world of the
record is strong enough (and will continually grow stronger) so that certain
artists who achieve fame in this medium
will consider it an end in itself, especially
since being successful in the record world
brings with it an economic reward in many
cases superior to the fees earned in public
appearances. These two worlds of sound
production are already so widely split
apart that in tests made by the Dutch
Philips between the same pieces played by
records and by living musicians, only 17
per cent out of 300 listeners (including
professional musicians) were able to give
the right answer.
This means that in spite of the enormous
difference between the two means of sound
reproduction, the record and its reproduction have already conquered most of the
qualities of the living performance, to a
point at which the specific characteristics
of the recorded sound (including its shortcomings) appear to the listener, educated
in the concert ball, less striking than the
similarities between both of them.
Probably we are only half way along the
road in the exploration of electronic sound
reproduction. This is one reason more why
we should give up the comparison of artists
and recordings with living performances.
Artists on records should be judged exclusively on their own merits as recording
artists, and records should be evaluated on
the highest level of present recording techniques.
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at home with AUllO
There
Is
LEWIS C. STONE
No Hi- Finality
I. Resurvey of living room results in revised requirements for
speakers and new self -built enclosure in de -luxe hi -fi system.
that letter writing, like the art of conversation, is on the wane if not yet a lost art. It is no paradox,
either, to remark that we'd rather talk than write; and
that we prefer spectation to conversation has become a
bleak fact, Fadiman's radio spot so -named notwithstanding.
Reflecting this condition we have been careful, in this department, to use "communication" when suggesting or acknowledging articulate reader participation. And now,
literally speaking, it has happened: this time about an
equipment change, a topic on the agenda of this department. One of our readers has put tongue to mike and sent
us a reel of tape -talk recording a communication, or audio note, about speakers -the cone and voice -coil kind, that is.
THEY TELL US
Fig. 1. Objective: at- home-with -audio conditioned speaker
system. Behind plastic grille, a three -way system combining
two Bozak woofers and a Bozak mid -range with AltecLansing tweeter, in self -built infinite baffle.
In the transcript that follows further along, reader Schwartz
explains in his own pointedly laconic words why (this happened less than a year after his then finalized hi -fl system
was described in these pages, March, 1955) he decided to
change from a two- to a three -way speaker system, from
bass reflex to infinite baffle housing-which he built himself, and that too he describes, from lumber cut to furniture
finish.
We find it difficult to resist inferring (as would you, in
our place) from the following dissertation on the savories
of hi -fi, that between one year's hi -fi show and the next,
life for the confirmed practising hi -fi enthusiast is a rather
aromatic mixture of blessings enjoyed now with a tantalizing, but bearable, suspense as to blessings yet to come in the
hi -fi thereafters. There's always a Fl "'-"' in his future.
And they tell us that it just ain't the same system, come
the aftermath of getting booster shots of hi- fidolatry at
those revival meetings called audio shows. And how else?
The customers are prodded and primed and educated the
year around by the hi-fi press (such as, respectfully yrs,
AUDIO, et al). Then, naturally they are completely fascinated, stimulated and won over by the massed "sight of
sound" at one audio rodeo or another. Indefatigably at
bray day after day, the fixtures at these exhibitions manage successfully (as they were intended, via the Iii -fi audio
dealer) to tune, amplify, spin, track, reel. treble, bass reflex, folded -horn, infinite -baffle, and catenoid their ways
into ranch and split -level, apartment acid attic. basement
and boudoir, or wherever- singly and in droves (on which
all depended). And of course the "way" was paved with
sound hi-fi dollars, to a guestimated top of near one hundred million, this past year.
The Forever Buyer
Having managed over some years to get the affordable
best in audio equipment, our hi- fier- of- theauonth was recently urged by "popular" demand (that is. sonic friends,
as we shall see later) to do something about the speakers
as they sounded "in the room of their location." Not that
the speakers in use were less than the best of their kind,
but that they seemed to these experts, to get less than their
just due in that rooms acoustic properties, structural characteristics, and space limitations. Like him (and you, and
you) these audio friends had learned, when considering
speaker -behavior "at home" to get themselves into a decidedly subjective state of (to coin a phrase) "just listening
around for the right feeling."
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MARCH, 1956
Fig. 2. Mock -up of installation in cabinet
of extra -heavy veneer lumber. Lower
compartment is full size Bozak enclosure;
upper has been added to hold hold -over
tweeter. T -pad on shelf, at left.
Fig. 4. Corner of well- stocked workshop
shows heavy veneer panel under clamps.
Other tools shown: Delta radical saw,
band saw; Stanley portable router; Lestro
Scintilla saber saw; Jorgensen wood
clamps; Pony bar clamp fixtures.
Fig. 3. Isometric view highlights simple building method. Heavy strips are secured
to flats as in pallet or skid type construction. They reinforce corners when panels are
fitted together. Inset shows placement of Kimsul curtains to eliminate internal
standing waves.
Listening to these people, "flat" as well as with the inner
ear of acquisitiveness, our reporting reader was a somewhat
vulnerable hi -fier with throbbing, exposed audio -tory nerve
sensitive to all and sundry in the speaker line, that trekked
from booth to booth at a recent carnaral du son (N. Y.) His
was an errand of decision, not merely a foray by a window shopper who, even as he scans the merchandise, intones a
"good -bye" to many a good buy before (finally) he lets out
the "hello" of acceptance leading to purchase.
We daresay that as a hi -fier yourself we doubt you'll
play surprise when we report that, like you, your hobby
brethren also dabble in other forms of gadgetry. Anyway,
the hi -fiers we have visited turned out to be combination
"pic (for picture) and pickup" fans. For them, the tangible
realism of stereophonic sound is opposite- numbered with
a Stereo -Realist camera or the like. For one of them, visited
recently, a Ilasselblad camera with accessories (costly?!)
is in the offing (ex a Contax). Naturally, it is often a
toss -up which of these hobbies will be shown off first to the
visitor: color slide or movie reel; or sound unreeled from
disc, or spooled from live -recorded tape reel. But for all of
his hi- flying, our combo -hobbyist is a responsible person
that is, responsible for hundreds of millions of dollars in
purchases for Iiving in the round -and per annum, too.
-
The Buying Complex
And we are told that a good deal of switching of make
or model, or choice of an entirely new hi-fi additive (for
AUDIO
Fig. 5. Bozak assembly in place, with Altec- Lansing tweeter
on shelf over. Non -resonant baffle is monolithic Chemstone
fitted to framing over gasket, secured with bolts.
MARCH, 1956
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Fig. 6. Sub -vital statistic: Orderliness of cabled
wire -up is recommended, but curl -paper wire -do
is practised. T-pad for treble attenuation on top
shelf, crossover on bottom. Note bolts holding
baffle for woofer -mid -range speaker array.
Fig. 7. Saran grille cloth covers front and two
sides of infinite baffle enclosure. Owner shown
putting body -English into lob of stretching fabric
tight and plumb as he fastens lap -over to rear
panel with automatic stapler.
instance) it due not only to what the engineer has put in
for the ear to "see" but also what the designer (who may
be the same person) has with corresponding skill put on
cosmetically for the eye to want. More subtly, but powerfully effective and decisive, the buy-ways of the deep -dyed
hi -fi buff are sometimes a little on the devious side, traversed
within the envy -clad walls of an enclave of small frustrations seeking compensation. Also that the final buying decisions may perch a- straddle on the bastions of brag and
boast : those solid, two- fisted, snob- nested allies of the seasonal or annual sell- and -purchase routines. (On which we
all depend).
Then. too, a sense of competition with one's best hi -fi
friends is vitally a factor in the big surge behind many an
urge to splurge. Maybe lots of brand new models of hi -fi
components are bought long before their earlier counterparts are ready for the discard. More circumspect. essentially, are the decisions made with regard to speakers, as
the wisdom of having chosen speaker A over B comes to
light perhaps only after you've bought and lived with either
or both, were that possible. You buy your speaker after
having it demonstrated (in and out of comparator labyrinths) and maybe a glance at its specifications and engineering data. But the fine performance levels that claim
the eye, via tabulation and published response curves, are
not always and infallibly as fine seeming to the more subjective (to the point of being capricious) ear. In these
things nature holds all the patents. So far all we've managed are piddling infringements. As to speakers, do not
think it presumptuous to leave it to the comparator labyrinths of your own ears to judge how well these patents have
been infringed.
First and last, speakers are the "blind mouths" of the
hi -fi universe today. Their sound is not alone, for your
room is the far from silent partner in these cone -and -horn
deals. The speaker's test is, finally, there. And whether that
test is passed depends on what your ears perceive pleasingly
of the emitted sounds. Directly yes, and subject of course to
your judicious exercise of the speaker's and the amplifier's
environmental controls. We all know that plaster of ceiling
and wall, wood of door and floor, void of opening. furniture
upholstered and unholstered, hangings, rugs, shelvings, and
so on, all of these absorptive and reflecting surfaces in your
(average) living room -the peaks, the null points they
cause and create -all of these, not to mention exactly
where in the room you have decided to place it, affect and
modify the sound -producing formulae engineered and built
into a particular speaker or system of speakers. Of these
angles of speaker selection, this month's subject is a ease
in point.
His Coneship, the Loudspeaker
Up to a point and down to a point (a built -in, braeketted
range) a speaker may produce sounds without lisp or guttural: harmonic or intermodulation distortion. that is. And
there's no heterodoxy in this fact that the ear's version does
not always coincide with the (for instance) curves of frequency vs. sound pressure seen in many an analytical circular issue about speakers. Actually these curves show nothing more than that speaker's response to a given frequency
with x- number of db of sound output. Below a certain frequency the speaker is so lightly loaded that it gives out with
very little fundamental, or so we are told. And how is this
sound output routinely measured? Of course the where of
it is a part of the process. A speaker on test is put through
its paces with a signal generator to which is coupled a recording oscillograph, which traces the response curves
mechanically. When the signal generator is producing (say)
30 cps, the bobbling recording nib will be resting on the
30 -cps line of the graph paper. As this moving finger writes
it will trace a most visible curve on the graph as 30 -eps
response, and so on along the spectrum, nice looking curves.
with contours a la Mlle. Monroe, pretty as all get out.
But the speaker (alas) may have no 30 -cps response;
instead frequency doubles to 60 cps. Yet this off -beat distortion will leave its signature on the graph paper as 30
eps despite the 60-cps sound actually produced. Inconclusive, and counterfeit to say the least, especially as to the
bass end. A more proper informative pay -off would be,
as some audio engineers suggest, to have the above curve
AUDIO
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MARCH, 1956
Fig. 8. Glue -screw procedure for firmness is feature of this
speaker housing job. Owner uses brace-operated screwdriver
for easier handling. Note bench is at comfortable working
height just below bent elbow.
drill holds screw -mate to drill
pilot hole for screw threads, shank clearance and countersink
for screw- heads, all in one operation.
Fig. 9. Chuck of hand -power
accompanied with a curve opposing distortion vs. frequency,
or a constant distortion contour curve, as well as indicating
the damping factor of the amplifier driving the speaker.
Then, they say, would your speaker -questing hi -fi buyer be
happier in making a proper selection.
Quite so, to all this, which about translates a procedure
for testing loudspeakers, suggested by ASA and RETMA
as points t be covered in any published data of such tests:
1) Recording of amplifier damping taetor. 2) Reference
of acoustic output to a specified absolute level. For a
speaker may have extended low- 1regneney response at very
low output, but poor low- fregueuey at any appreciable
power, due to the inability of the cone to move far enough.
(For, in these circumstances, as stated in this department
October 1955, "... an amplifier vents torrents of decibelicose
tantrums upon a mismate like an under -excursioned cone
... "). 3) Frequency response data should also include measurement of the fundamental output: something like an associated distortion- frequency curve, discounting distortion
components. 4) distortion measurements should be related
to acoustic output as well as to electrical input, since the
latter does not take into account speaker efficiency. Ten
watts into speaker A may produce less sound than one watt
into speaker B; so the damping factor has to be noted, or
else measuring the instantaneous value and phase of the
speaker impedance at different frequencies. (The foregoing
paragraph is adapted from "Handbook of Sound Reproduction," by E. M. Villchur, Chapter 18, AUDIO, April
1954).
Moreover, the points that have to be considered by the
hi -fi buyer are enumerated in as many as nineteen "Facts
Affecting the Choice of a Speaker," by J. H. Newitt in his
hook. High Fidelity Techniques.
Time now for your reporter of the hi -fi scene to leave
these areas of speculation as to the nature of the hi -fi
market and its customers' finest hours. Let us now deal
with the buying (and building) decision of our subject
reader, and its consequences. We give you reader Joseph
Schwartz who has been paying his substantial hi -fi (and
camera) bills over the past several years with his (presumably) substantial earnings as manager of the contracts di-
AUDIO
vision, Institutional Products Corporation, a New York
distributor of laboratory and hospital equipment. Ile
talked the following facts into an Electro -Voice 950 mike,
onto a five-inch reel of tape moving at :3 j ips in a Federal
model 47 -A tape recorder. The reel was mailed to us; we
played it back on an identical machine, had it transcribed,
typed, and fitted among these dewy paragraphs. (Incidentally, the above portable unit is adjunctive to the portable
Ampex 600 tape recorder with the 620 amplifier -speaker
unit: all fresh -bought.)
A NEW SPEAKER SYSTEM: WHY
AND HOW IT WAS INSTALLED
Tape- Recorded by
J.
Schwartz
The Build -Up
'flier are three reasons why I decided to install a new speaker
system. 1'11 list then in the order of their importance to me:
1. Some snide remarks by some of my friends whose opinion
I value most highly, to the effect that my highs were all right,
but I seemed to be lacking in middles, while the lows left much
to be desired.
2. I listened to the G. A. Briggs -Wharfdale demonstration at
Carnegie Hall last December. It left me impressed with the fact
that recorded music could really be reproduced in a fantastically realistic manner.
3. My attendance at the recent audio show in New York (with
the usual set of ear -muffs in my- left pocket).
I was then and there faced with the problem of what type
of speaker system. After a complete survey of nn- living room
and my present equipment I had, of necessity, to eliminate
consideration of a corner system, such as a Klipsch or a Briggs
sand -loaded Wharfdale unit. There was then the choice between
a conventional bass-reflex type of enclosure and an infinite
baffle.
I had happened to spend considerable time in the Bozak
booth at the fair and after reading their literature I found
that they were the outstanding exponents here of the infinite
baffle type of enclosure, and that they had designed their
speaker units tó work most satisfactorily in that type of enelosúre.
25
MARCH, 1956
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to the cabinet housing I decided to use vinyl foam. This is a
very new product, used in 1956 autos to form shock and impact- absorbing panels around instrument boards and for sun visors. It is an extremely interesting material in that it is
composed of many tiny cells, like balloons. There is no interconnection between these cells such as you have in sponge foam
rubber. I used this homogeneous substance as gasket material,
and drew the Chemstone panel up against it with stove bolts,
spaced about eight inches apart. (Fig. 6). The combination of
Chemstone panel and the vinyl foam sponge gasket seems to
accomplish the results I was after; namely, no transmission
of vibration from the panel to the body of the cabinet. (Kindly
explain sometime about the bolls, trhich contact both panel
and cabinet. En.)
The Processing
Fig. 10. Delta drill press drives steel drill into Chemstone
baffle to locate holes for bolts used to secure it to framing
of enclosure.
I was most impressed by their 3 -way, B -310 system. But
unfortunately, being a cliff dweller and having a living room
that measures only some 13 by 14 feet, my first compromise was
to decide on the B -305, a 3 -way system in a smaller housing,
using a mid -range, two 12 -inch woofers and two sets of tweeter
arrays. I had been using an Altec- Lansing 802E tweeter with
the two-by -four H808 horn in my hi -fi system. As that unit
represented an investment of over one hundred and fifty dollars, and as I had had no criticism from my expert Iii -fi
buddies on the quality of my highs, I decided to include it in
the new system, using just the two Bozak woofers, their midrange, and crossover. The completed installation is seen, as
located and used, in Fig. 1.
Of course I knew I would be faced with the necessity of
balancing the efficiency of the Altec tweeter with the other
units, but this presented no problems as I inserted a T -pad
in the tweeter circuit to cut down on its efficiency (Fig. 2).
Subsequently some of my more knowing musical friends came
up with special recordings. We had quite a session while these
experts balanced the whole system and I must say that the
resulting listening quality exceeded my expectations.
The
Building
My next problem was the actual construction of the enclosure, which I built according to the manufacturer's specifications, but modified, as shown in the isometric drawings, Fig.
3. And here I decided to make use of various materials, some
of which
the best of my knowledge -had not been used in
the fabrication of speaker enclosures, or are not widely used.
All of the books describing construction of speaker enclosures
stress the fact that they have to be heavily braced and reinforced, then glued, and fastened with screws.
It is true that you can get 3/4-inch plywood at practically
every lumber yard. However, in the building trades there is n
fir plywood that is 118 inches thick. And this is the material
I decided to use for the speaker enclosure (Fig. 4). I solved
the problem of panel resonance by using a product known as
Chemstone, a trade name for an artificial stone made by JohnsManville of a combination of cement and asbestos (Fig. 5).
Its most common use is for table and counter tops in chemical
laboratories. It comes in various thicknesses but I learned that
-inch of this dense, solid, monolithic material would answer
the purpose as a baffle.
To further isolate any vibration that might be transmitted
-to
/
The only finished wood surface is the top, which has been
made of a piece of mahogany -faced 4 -inch plywood. The grille
cloth completely wraps around and conceals all other wood
surfaces (front and sides), which are all wild-grain fir plywood. (Fig. 7). The entire enclosure is mounted on four 2 -inch
ball-bearing casters set back a proper distance so that they
are not visible from a seated position in most parts of the
room. Experience has taught me that all equipment should be
mounted on casters for easy cleaning and any possible servicing that may be required. The two moldings at top and bottom
of the finished cabinet. are what is technically known in the
building trades as chair -rail. They are obtainable from any
dealer who handles the products of United States Plywood
Corporation. Wire brads are used to attach this molding to the
cabinet. Normally this would be glued, but one has to look
ahead and if at some time the speaker units have to be taken
out, the grille cloth will have to be detached. Therefore the
moldings have to be so attached that they can be removed
easily, without damage to the fabric.
The Means and Tools
I found these tools very useful and labor-saving: Number
one, a brace with a screwdriver bit, as shown in use in Fig. 8.
Then a screw -mate tip to fit the chuck of a % -inch electric
hand drill, as in Fig. 9. The tip comes in various sizes. This
gadget drills a body -size hole for the body of the screw and
it countersinks the wood for the screw head, all in one operation.
The strength of a glued joint depends on the clamping pressure used during the setting period. The holes should be drilled
first, then both the plywood and the corner cleats covered with
glue (I used Eimers Glue -All). The two units should then be
screwed together and drawn up very tightly with good quality
cabinet makers screw clamps; (these are seen in Fig. 4 mentioned earlier). Then draw the screws up to their final tightened position. Leave the clamps on for a long enough time
for the glue to set, although this is not quite necessary because
the screws will hold the two pieces together quite securely.
Ordinarily a screw will not draw up the pieces tightly
enough, although it will hold them together very nicely once
the clamps have been applied for the final pressure. The sign
of a good glued joint is when the glue oozes out on the edges.
\Vipe off all excess glue immediately, before it has a chance
to harden. Assemble all corner cleats and parts completely, as
shown in the isometric drawing, (Fig. 3 above) before attempting to assemble the complete cabinet. The large holes in the
Chemstone panel were cut by a firm specializing in working
this material, or else the local Johns -Manville dealer will arrange to have it done. The mounting holes for the speaker can
be drilled with an ordinary steel drill, at slow speed. (Fig. 10).
Do not apply too much pressure and drill very slowly, in spurts,
to avoid excessive heating up and ruining the temper of the
drill.
The Finish
Books have been written on how to finish furniture. And
there are so many schools of thought that I can contribute
nothing except to give those who wish it the method I used to
finish the top of the cabinet. It is first sanded lightly. As a
bleached mahogany finish was desired, I used a product known
as Masking Color, bleached mahogany #4003 as manufactured
by the International Paint Company. The excess was wiped off
about twenty minutes after application.
(Continued on page 66)
AUDIO
26
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AmericanRadioHistory.Com
MARCH, 1956
Transformer Design for "Zero"
Impedance Amplifiers
N.
R.
GROSSNER"
a practical method that can reduce weight and volume of an
output transformer for zero-impedance output stages without increasing distortion.
A rigorous discussion of
'NSFORMERS have been irksome to
the designer of high -efficiency program amplifiers. He knows that
higher efficiency yields a smaller power
a
T-
transformer. But the output transformer, as used in class AB and B operation, ordinarily presents him with
rather severe problems, especially when
high power, low distortion, and wide
bandwidth are desired simultaneously.
Progress toward minimizing problems
associated with the output transformer
seems to take three major directions:
Eliminate the output transformer
entirely. Apparently this procedure substitutes new problems for old.
2. Use special circuitry to overcome
the "limitations" of the output transformer. Maclntosh' and Peterson,: using
high -quality transformers of special design have achieved notable success.
3. Devise circuitry which overcomes
transformer "limitations," using small
and comparatively inexpensive output
transformers. This article is concerned
with a development in this category.
1.
I,= 1y. +I,
power transformer of the same power
rating. The smallest size is obtained
by using a B supply with perfect regulation and fixed bias.
2. Wider bandwidth.
3. Lower inter -primary leakage reactance-reduces "switching" transients.
4. Lower effective primary capacitance. High transformer input capacitance limits the amount of low- distortion
high -frequency power from those class
AB, and B, amplifiers that utilize large
transformers with bifilar windings.
5. The foregoing advantages contribute to the feasibility of an economical
high -performance wide -band Class B,
amplifier employing a regulated B supply.
(2)
(3)
= (Ic +I;) -37.1,
Primary EMI.'
ED
(4)
XL
The voltage drop across (RG +R1) is
1,(Ro+R,)
=
=
[(Ie. +la)- 37M)(RG +RI) (5)
[(lc +Is) (Rc +R,)] JIm(Ra +R,)
(6)
71, is the quadrature magnetizing
current containing the distortion har-
Since
TABLE
I
TYPICAL WEIGHT REDUCTION DATA
AUDIO
POWER
15
35
70
STANDARD
LAMINA- STACK
TION
E1112
E1125
E113
1
1/4
13/4
13/4
ZERO IMPEDANCE
W
(LBSI
3.28
5.69
8.66
LAMINA- STACK
TION
E112
7/9
E1125
EI125
1
11/2
WEIGHT
W., W.
REDUCTION
350*
3.31
1.55
1.72
5.4
1.6
oip
(LBS)
2.12
420,
38°c
The "Zero- Impedance Transformer"
This writer's experience indicates that
a compartively small output transformer
specifically designed for the "zero" im-
pedance output stage'' provides performance characteristics at least comparable with the "large" transformer
designed for the conventional high -quality feedback amplifier.
The advantages this type of transformer affords when fed by a zero impedance stage are as follows:
1. Small size. Typical weight reduction
is approximately 40 per cent (See
TABLE I). It appears feasible to design
a high- quality output transformer only
11/2
to
21/2
times the size of a 60 -cycle
* David Bogen Corp., Transformer Division, 29 Ninth Ave., N. Y. 14, N. Y.
Maclntosh & Gow, "Description and
analysis of a new 50 -watt amplifier circuit." AUDIO ENGINEERING, Dee. 1949.
°A. P. Peterson, "A new push -pull amplifier circuit." General Radio Experimenter, Oct. 1931.
J. Miller, "Combining positive and
negative feedback," Electronics, March,
1950.
C. A. Wilkins, Pat. Pending: "Controlled Positive Feedback."
AUDIO
y
The limitations are:
1. This type of transformer appears
to be limited to use in the "zero" impedance output stage.
2. The continued need for the type of
elaborate winding schedule often used
in high -quality large transformers.
3. The continued employment of the
same high -quality core material as used
in the traditionally large transformer.
4. While the cost is substantially less
than that of the large transformer, its
cost is higher than the small P.A.-type
transformer which it may superficially
resemble because of its smaller size.
Distortion
monies, it is clear that the distortion
producing voltage drop IM(Ro +R,)
subtracted from the input voltage EG
produces a component of the voltage E,,,
having a distortion term across the primary reactance XL. If we assume I,v is
all harmonics, then the maximum fractional distortion DT appearing across
the effective primary reactance is
Dr
/m(Ro +R,)
I,(Ro+R,)
IM(RQ +R,) EP (Ro +R,),
Ep
XL
ED
(7)
(8)
Low distortion has a decisive effect
on the size of the output transformer.
The equations pertaining to distortion,
based on the equivalent low- frequency
circuit (Fig. 1), follow:
Exciting current
lc-37M
(1)
Iy= core loss current
where Ic = in-phase
and IM =
quadrature magnetizing current
total primary current
MARCH, 1956
Fig. 1. Low- frequency
equivalent circuit.
27
www.americanradiohistory.com
AmericanRadioHistory.Com
DT= (Ro + RI) /XL,
(9)
and the distortion factor due to the
transformer alone is
ors
D, =R, /XL
(10)
The EMF, E,, across the primary shunt
reactance (with the distortion component), in turn causes the load current
lî to flow through the secondary d.c. resistance and load resistance.
Since we expect to handle the distortion parameters in some detail, it is now
desirable to establish the exact transfer
ratio between input and output. If we
solve each loop of the network (Fig. 1)
using Kirchoff's Law we can write the
exact equation :
1
+Rc
It
where R = R2+ RL, and
E.
R,
E,
X,
(12)
RL
Multiplying these two equations and
separating the real and quadrature
terms,
= 11
+KL
F4ll
-i l
XL/
¡¡
\I
(13)
/
+Rc + R
E,/Es= (1 + R, /RL) (1 + R, /Rc + R, /R)
R,
1
(14)
1-i XL I +R+
R, R,
\
Re
/
that the transformer distortion factor
(again assuming that the magnetizing
current I,, is all harmonics) is the j
term in Eq. (14),
so
D"
-
XL
\1+ RI/Re +R,/R/ (15)
or D, R, /XL
(16)
What is especially significant is that
if Ro r R, or better still if Ro = 0, then
the total circuit distortion is determined
by the trànsformer alone.
Size
of the Conventional Transformer
Before attempting to reduce the size
of the conventional output transformer
let us see why it is larger than a power
transformer of the same rating and at
the same time derive an expression for
its size in terms of copper losses and
distortion.
Assuming R, = R,, which is the usual
case in a transformer designed along
traditional lines, its loss factor 1 /Q,
will be
//Qs = R, /XL + R, /XL = 2R,/ XL.
(18)
XL is established after a number of con-
siderations:
(a) The lowest frequency the amplifier
is to pass in accordance with relative
low -frequency response in
' The
writer is indebted to D. Wildfeuer
of Arma Corporation for this simple formulation of maximum distortion.
then traditionally have the most bearing
on the size of XL. Therefore XL is established by Eq. (9) and the following
relationship
XL =d,RL,
(23)
where d, is usually an integer in the
range of 3 to 6 (empirically determined)
in order to keep the "ellipse as narrow
as practicable" in the high -quality conventional output transformer.
The weight W. of the transformer
(which we will also refer to as the
"standard") after combining Eqs. (18)
and (23) may be expressed' by
IV, cc Qs3/2 a (dRL /2R,) :., (2.1)
1
d6 = 201om
°1-.lR/L'
(19)
where
1/R =[1 /(Ile +R,)] +1 /R; (20)
(b) The maximum permissible distortion. This is a function, at high power
levels, of the flux density B n, in the primary winding. Although the maximum
distortion factor is
Dr= (Rc +R,) /XL,
(9)
the inductance, being a non -linear function depends on what the effective core
permeability µe (see Fig. 2), is for a
given Bm, which is, in turn, a function
of the maximum voltage across the primary, in accordance with
E,.= 1.44NAB.I1f 10 -e
(22)
Size Reduction Methods
Equation (21) suggests several ways
of reducing the transformer size.
(a) Increase the copper losses by K;
that is, to 2R,K /RL. This however
would produce more distortion than the
conventional transformer in a zero -impedance circuit.
(b) Reduce the primary reactance by
K; that is, make new reactance XL /K.
This would also produce more distortion
from the small transformer than the
large one used in a zero-impedance
stage.
(c) Make the distortion of the small
transformer the same as the large one
in the zero -impedance stage. A special
procedure for accomplishing this will
be described.
where N = primary turns,
A= effective core area,
and f=
lowest frequency of operation.
Then to be certain that at low- frequency
high power levels we do not exceed DT,
we must select a reasonable value for
Rif to prevent XL from falling below
the minimum established by Eq. (9).
(c) In addition to the foregoing, the
load line at high power also must be
considered. At power levels near maximum, the effective load on the output
tubes becomes reactive, the load line becomes "elliptical," and Ra increases due
to phase shift in the feedback loop. The
impedance Z of XL in parallel with RL
reduces the effective plate load impedance to a value lower than the optimum
(established at mid -frequency) required
for maximum power transfer. The lower
impedance increases° the voltage drop
across Ro (power wasted), thereby decreasing the available low- distortion
power at the lowest operating frequency.
It is the last two considerations which
A Special Design Procedure
Equation (15) tells us we would obtain zero distortion if R, could be reduced to zero. Although this is not phys-
' M.LT. Staff, "Magnetic Circuits and
Transformers. Wiley: 1943, p. 228,
wherein it is demonstrated that Q ce K.',
where K. is a factor by which the linear
dimension of the transformer is changed.
Q is therefore proportional to volume/'
°R. Lee, "Electronic Transformers and
Circuits." Wiley: 2d ed. 1955 pp. 158, 167.
10000
8000
6000
Fig. 2. Flux density
vs. Mu.
(Courtesy Magnetic
Metals Co., Cam-
den, N. J.)
4000
3000
2000
.6 1000
800
600
600
300
200
100
(and weight' /').
i
EMIR
ii%
M
:::I
mloMM.
1111%
s/.tiV
fsi/i1
111111111110E./111105/111M1
mimatt
iirmmf'
IIM MINCÍltilli
11-
M
PMIli
100
200
GAUSSES
B,,,,
AUDIO
28
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AmericanRadioHistory.Com
MARCH, 1956
ically possible, we can make R, very low
by decreasing it from its customary value
R,=1? and increasing R. This is tantamount to putting most of the copper
losses into the secondary. Li transformer
vernacular -run the secondary "hot"
and the primary "cold." The transformer
designer can now proceed as follows:
Keep the new transformer copper efficiency the same as that of the standard,
but make new transformer primary d.c.
resistance
RA= R,/117,
(25)
where K is the factor representing the
degree to which we expect to reduce the
size of the standard, and new transformer secondary resistance Ra
so that
Ra= R,(2 -1 /K).
R-t + RD= R, +Rr
New transformer primary QA is the
same as large
Q.4=
where
Q,= X.t /R.4
X.t=X,./K
(28)
(29)
Transformer secondary
Qa= XA /R,,,
(30)
Qa= (R.4Q,) /[R,(2- 1 /K)]. (31)
Now total new -transformer dissipation
1 /Qx
is
1 /Qc =
lí (2- 1/K)/Q,
= 2K /Q,.
(1 /Q,) +
1
/Qs= 2KR,/(deR,,)
1. Flux Density
(32)
(33)
L = 3.19NtAu.e10 -8 /l
=1i.
TABLE II
Typical Silicon -steel Magnetizing
Current Harmonic Components
with Zero- Impedance Source'
Ba
Gauss
(34)
(35)
The weight ratio of large and small
transformer is then
16'8/1V,8
=K."
(36)
Examine the consequences of this pro cedure. The total distortion with our
standard transformer is
Dr= (Ra + RI) /XL
(9)
and of our modified transformer is
Do-
L/K = Il, /XL
(37)
And comparing the distortion factors
DT and Do by dividing (9) by (37)' we
have
Dr/Do= 1 + (RG /R,)
(38)
The intrinsic distortion of the standard
transformer is the same as that of the
smaller transformer. But when the
standard is used with a substantial
source resistance, it yields more distortion than our new smaller transformer
in a zero-impedance output stage.
IIere we have a technique that looks
very promising. However, having ignored a number of important parameters, we should try to see what prac-
AUDIO
(39)
where l = length of magnetic path
does not fall below the value needed
to maintain Lo = Le/K.
(b) It is also necessary now to reconsider the previous formulation for distortion which was based on the supposition that all of the magnetizing current.
was harmonic. Because, as Partridges
has shown, the percentage of third and
fifth harmonics in the magnetizing current is a function of the operating flux
density. Table II summarizes such data.
And multiplying (34) by (24),
Q8 /Q,.
and Distortion
(a) When XL is reduced by a factor
of K, the flux density is generally increased (see Eq. 22), so it is essential
to insure that ur in the equation
(26)
(27)
TABLE Ill
RELATIVE DISTORTION
tical limits must he assigned to K by
studying each neglected parameter:
1. Flux density and non -linear nature
of X,.;
2. Power supply regulation at low
frequencies;
3. Core loss;
4. Temperature rise of the transformer;
5. Bandwidth; and
6. The Class B, high -frequency response and regulation.
Percentage of
3rd Harmonic
Percentage of
Sth Harmonic
100
4
500
1,000
3,000
5,000
10,000
7
1.5
9
2.0
2.5
3.0
5.0
15
20
30
1
Rc/R,
Kd
0.75
0.5
0.5
2
1.5
1.0
LO
2.0
2
Values of 1.5 and 2 for Kd are deliberately chosen to represent the probable
maximum distortion increase if the flux
density doubles due to a choice of K _ 2.
Table III indicates that the small transformer produces the same or less distortion than the large, provided K (and
thereby Kd) is not made too large.
(c) Since there is usually some degree
of output tube unbalance, polarizing
d.c. in the primary has two important
effects:
(1) the effective µe is decreased, and
is now obtained from the family
of curves in Fig. 2 after estimating the ampere -turns per inch, H:
H =NI /l
(42)
where N = primary turns
I= polarizing d.c. current
1=
length of magnetic path, inches
(2) the magnetizing current now contains even harmonics as well as
odd. It is therefore desirable when
reducing the size of the standard
transformer that H be kept the
same (or smaller). This can be
easily accomplished in practice.
performance.
(a) In Fig. 3 neglect Re (to be
studied later), and R, (since R3 < RL).
First assume perfect power supply regulation so that the output tubes must
furnish the following VA:
(40)
VA =
1
N. Partridge, "Harmonic Disturtiun
in a. f. transformers," Wireless Engr.
Sept. -Nov., 1942.
° R. Lee, op. cit, p. 163.
MARCH, 1956
(43)
F
R'
-j ER° d
2
2
1
(44)
VA= Po- jP,, /d
(45)
VA= Po(1 /d)
(46)
where Po = real watts audio
(41)
(R,/XL) Kd
R, Kd
If, for example BM =5000 gauss and
Bo= 10,000 gauss then Kd = 0.3/0.2 =
1.5 (neglecting fifth harmonics). Equation (41) is therefore a more accurate
version of Eq. (38).
For help in designing the new transformer, Table III lists likely values of
Kd and the corresponding values of
Ref /R, and DTDo.
j
8
VA=
and
(Ro+R,)XL- (1+Ra)
1.5
2
1.5
2
Power supply regulation is quite important to the high -level low- frequency
increases when operating at Bo (due to
size reduction) rather than Bd1 (the flux
density of the standard transformer).
Then
Dr
Do
2
1.33
1.5
2. Power Supply Regulation
On the basis of this data we shall define
Kd as the factor by which the distortion
Do= (RIh
lL/K ) Kd=KdR,/XL
Dr/D..
-j
vá
Fig.
ep
3.
Low- frequency impedance.
29
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AmericanRadioHistory.Com
Equation (45) tells us that at high
power levels PO /d reactive VARS will
be supplied to the magnetic core. Since
the VA furnished by the output comes
ultimately from the plate supply, it is
apparent that distortion is higher at
high power levels when using an unregulated power supply.
We can now attempt to establish suitable criteria for d0= XLI(KRL).
The VA ratio between small and large
transformers is
1- jK /d
1 -j /d,
V1+ (K /d)2 (47)
V1+ (1 /d,)2
If we assume certain values of d, we can
tabulate (Table IV) the VA increase
VA.
VA,
VA INCREASE
VA./VA 10 log
M, db
d.
do
5
2.5
1.055
3
1.5
LO
1.11
0.232
0.45
1.27
1.59
2.02
2
1
0.5
0= temperature
where
20 log
Ls= 3.2N2
e/
a-
1.04
demanded of the power supply at high level low frequencies.
If, for example 4=3 at lowest useful frequency and is reduced by K = 2
(a weight saving of 65 per cent) only
11 per cent more VA is demanded from
the power supply at that frequency.
Under these conditions the measured distortion in the zero impedance circuit at
the lowest frequency is found to be unusually low, and easily comparable to
the distortion figure for the large transformer in a conventional feedback amplifier.
(b) When Ro =O, but the power supply is not perfectly regulated, experience
indicates that a quite sizeable but less
dramatic size- reduction is feasible. Examination of Eq. (41) has suggested to
the writer a more modest value of K in
this case. Experience has shown that
with a choice of K = 1.4, a weight saving
of about 40 per cent is obtainable with
a distortion figure equal to or lower than
that of the large transformer in an unregulated conventional feedback amplifier.
3. Core Loss
Analysis of the effect of increasing
core loss (decreasing Rc) when K =2
indicates a negligibly small change in
high -level low- frequency performance,
so core loss may safely be ignored except perhaps when IC, 2. This would
be the case where we succeeded in reducing the output transformer to the
size of a 60 -cps power transformer of
the same power rating.
4. Temperature Rise
Since our (low -distortion) conventional output transformer is much
(53)
a = total copper depth of wind-
ings
Substituting the equations for Lo and
into (50) we get
L
-K
(49)
B, =Chp,
we neglect the various winding
I
L.
R,+R, +R,
R,
(55
transformer
B.= CO.,
capacitances and shunt core loss Rc, the
following bandwidth equation" is informative (see Fig. 4)
(54)
By substituting RA and RB in (55), we
get for the bandwidth of the small
sulation. On a thermal basis, therefore,
the conventional transformer may be reduced in weight by at least 65 per cent.
5. Bandwidth
CChl~e R,
where Ch is a complex constant describing the geometry of the core. If Roc R,
we can write
that our new transformer rise for
K =2 will be in the range of 20° to 40°
C. A temperature rise of 40° to 55° C
is permitted for military and commercial transformers, respectively, with
Class A (105° C final temperature) in-
If
10-8
d = insulation between windings
BT =
-
( K "/s)
(d +3)
winding length
b=
rise, °C.
The relative temperature rise of the new
transformer will be
(W.)
b
where 31 = coil mean length turn
e= a constant
P, = losses
w= weight
9,
(52)
/R,
+
and
So
TABLE IV
M =
larger than its equivalent power transformer of the same rating, it runs "cool,
that is its temperature rise is in the approximate range of 100 -20° C.
If we use an approximate equation for
temperature rise10
/w2/,
(48)
00 =cP,
R,/K+R, (2-K) +RL
R,/K
K(2R,+RL)
Ba =
Chl+e
(56)
(57)
R,
Dividing (57) by (54)
I
I
I
is ,'2
2
t
°
_J
Fig. 4. High- frequency
Ì
fh R, Lo
BT= fl=Rv
where
(50)
fh = 3db down high -frequency
(X, =Rs)
ft.= 3db
down low -frequency
(R,,= XL)
R,= R0+R, +R2+RL
1 /Ry= 1/(Ro +R,) +
1
/(R, +RL)
(51)
equivalent circuit.
Bm/BT-K
(ReRRo)
(5g)
or
Bc/BT
K(I+Ro)(1-Ro)
(59)
In words, our new transformer in a zero impedance output stage has at least K
times the bandwidth as the large.
6. Class B, High-Frequency Performance
(20)
L, = total leakage inductance,
X, = leakage reactance
L,= primary shunt inductance
The relative high-frequency response is
"o R. Lee, op cit. p. 60. This equation,
while intended for large transformers,
serves our purpose here.
n MIT Staff, "Magnetic Circuits and
Transformers." Wiley: 1943, p. 484. Also
"Radio Engineers' Handbook." McGraw -Hill: 1943. p. 388, Fig. 26.
see F. Terman,
The "K- modified" transformer has important beneficial results in a class B1
amplifier with zero source resistance and
a well regulated plate supply.
(a) The interpriivary (half -primary
to half-primary) leakage reactance is
lower. If K =2, the dreaded "notch" due
to switching transients12 is moved up an
octave, approximately.
(Continued on page 68)
a A. P. Sah, "Quasi-transients in Class
B audio -frequency amplifiers." Proc. IRE,
Nov. 1936.
AUDIO
30
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MARCH, 1956
AS MODERN AS
AS BEAUTIFUL AS
sot
d&
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dEueb
A
11
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D44
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-- S,,,,ii711,m
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14'
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v`e,
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toot.
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fr.
will produce a thrilling
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ELECTRONIC APPLICATIONS DIVISION
SONOTONE CORPORATION
ELMSFORD
www.americanradiohistory.com
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NEW YORK
litt-
FM
A. Before answering this question directly,
Limiter
purpose of a limiter in an
FM receiver? George Klima, Valley
Stream, N. Y.
A. The purpose of a limiter is to remove all
amplitude modulation from the signal
which is to be fed to following stages.
Basically, the limiter circuit is that of an
overloaded amplifier. Signal voltage fed
to the limiter may vary in voltage because
of noise pulses, distortion in previous
stages, and other reasons. The limiter plate
current reaches its maximum on each cycle
of the signal long before the peak voltage
of the signal is reached. Consequently, any
further increase -such as may be caused by
static, ignition, or what not-does not affect the amplitude of the output signal. The
frequency -modulated signal is fed out to
the succeeding stages without any amplitude modulation. If the signal strength is
lower than a certain value, called the
limiter threshold, the limiter functions as a
square-law amplifier and the limiting action
is lost. In some circuits, two limiters are
Q. What is the
it is well to consider some of the factors
which cause the level of the music you hear
to differ from station to station and selection to selection: 1) There is a difference
in signal strength of the stations, depending upon the moisture content of the earth,
the distance between transmitter and
receiver and other .conditions; sonic
stations lire always stronger than
others. The AVC /AGC in the tuner or receiver does not entirely overcome these differences. 2) The policies of the stations
may differ somewhat as to the level they
wish to use when reproducing music; some
believe that the music should be lower than
the speech level so that commercial announcements will tend to gain the attention
of the listeners. 3) Different pieces of
music and, indeed, different performances
of the same piece of music vary in dynamic
range; some may be uniformly loud, others
uniformly soft. 4) Differing levels are used
when recording discs and tapes, even for the
sanie dynamic range to be produced. It is
difficult for the broadcast engineer to know
AUDIOCLINIC
JOSEPH
? ?
GIOVANELLI
used to obtain a further limiting action and
consequent improvement in performance.
Shorter Long -Plays
are some twelve -inch microgroove
records made to play for only sixteen minutes or even less? Frank Geisler, N. Y.
A. The limitations of the dynamic range of
a record are primarily caused by the thickness of the groove walls. This is especially
true at bass frequencies. This is caused by
the fact that when the volume is very high,
the distance traversed by the cutting stylus
is such that it tends to break through the
groove wall and partially modulate the
adjacent groove causing a phenomenon
known as echo. It can be clearly seen, then,
that if the groove walls are very thin, it
Q. Why
becomes necessary to compress the dynamic
range to a serious extent. By increasing the
thickness of the walls the dynamic range
is kept intact but, since such grooves take
up more space, there must be fewer of
them, resulting in shorter playing time.
Another reason for doing this is that as
the recording stylus nears the center of the
record, high- frequency attenuation takes
place, despite slope-control equalizers. To
maintain frequency response as well as dynamic range uniformly over the entire disc,
the stylus is not permitted to approach the
center as closely as is the case with standard records. This also causes the playback
stylus to describe a relatively small arc,
so that it traces more exactly the path of
the recording stylus, minimizing tracking
error and its consequent distortion.
Audio AVC
Q. When listening to records or FM, I
have noticed an annoying variation in volume level. Would it be commercially feasible to incorporate in new amplifiers a circuit similar to AVC/AGC that would boost
or reduce the gain so that at a given setting
of the volume control, regardless of the
original recording level, all music would
come out of the loudspeaker at the same
J. Klein, B'klyn
intensity level!
exactly where the peaks are to come and
so, quite often, he must set his equipment
in such a way as to allow for the maximum
possible loudness; if such a level is not
reached, even very loud passages may be
reproduced more softly than the listener
would like to hear them. 5) Sometimes the
variations are in the apparent loudness of
the records rather than in actual sound
level. Microphone placement as well as the
type of material being listened to can cause
tremendous differences in apparent loud -
ness.
We do not feel that n circuit could be
designed which would overcome all of these
problems; although uniform volume were
being produced, the ear would still hear
differences in apparent loudness. However,
such evenness of volume would be esthetically undesirable since music, speech, and
other program material would be rendered
hopelessly monotonous by the loss of all
dynamic contrasts.
Phase Inverter
Please describe the principles of operation of a split -load phase inverter.
Carl Pollack, Natick, R. I.
A. This type of phase inverter, or any
Q.
other, is generally used to feed push -pull
stages from a "single- ended" source. To
do this, the circuit must be such that when
one of the push -pull grids is being made
positive with respect to its static bias, the
other is being made negative, with the reverse being true on the other half of the
cycle. The split -load phase inverter is shown
iu Fig. 1 and is what its name implies. In
it conventional triode circuit, the full load
is placed in the plate; in a cathode follower,
it is in the cathode circuit. In this arrangement, however, half of the load is in the
plate circuit, the other half in the cathode
circuit. In operation, when the grid of the
phase inverter, V is made negative with
respect to its static bias, the flow of plate
current decreases, causing a decreased voltage drop across R This causes the plate
to become more positive which, in turn,
causes the grid of V to which it is con neeted, to become more positive also. This
decrease of plate current also causes decreased current to flow in the cathode load,
R
R,
which causes the cathode to become
more negative. This, in turn causes the
grid of V to which it is connected, to be
driven negative. Notice that the cathode
load is made up of two resistors in series,
R, and R,, with the bottom of the grid
resistor,
connected to their junction.
Thus it can be seen that the voltage drop
across R, will provide the necessary grid
bias for V,. When the grid of the phase
inverter, V is made positive with respect
to its static bias, those circuit elements
which were made positive before are now
made negative instead and those which
were made negative before are now made
positive.
R
Two Speakers in one Cabinet
Q. ll'hat is tl. difference in performance
between having one speaker in a given
size enclosure and having two speakers in
the sanie size enclosure?
Dean M. Tonelli, Chicago. Ill.
A. In the first instance, let us assume one
speaker in the enclosure. Let us further
assume that a program level of 10 watts
is being fed to this speaker, causing the
voice coil to move x inches during any one
cycle. Then, a second speaker is introduced
into the circuit, and we shall assume it to
be identical with the first with respect to
size, impedance, frequency response, and
manufacturer. It is necessary that this
second speaker be phased properly with
respect to the first. Assuming the same
power level of 10 watts, 5 watts will now
be delivered to each speaker. The loudness
level as heard by a listener will be the
same. However, the cones will now travel
x/2 inches per excursion. Here, then, is
the basic difference. Although the acoustic
power produced by the two speakers in the
(Continued on page 6.9)
600
CI
Fig. 1.
F ROM
PRECEDING
STAGE
600
V2
0.1
C2
,.
PAPER
VI
v.
PAPER
V3
C30.1
600
v. PAPER
AUDIO
32
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MARCH, 1956
ORGANIZING THE CONTROLS
....the key to high fidelity
Every control on a well designed, honestly considered high fidelity instrument has a specific useful function,
related to each of the other controls.
Operation of the Prelude, Harman -Kardon's new 10 watt printed circuit amplifier, illustrates this
point well. With the function selector, choose the type of program material you plan to listen to (tuner,
phono, tape or T.V.). Select the correct record equalization settings for the particular record to be played,
using the separate low frequency turnover and high frequency roll-of controls. To minimize turntable
rumble operate the rumble filter slide switch. With the loudness contour selector in the uncompensated position,
turn the loudness control to a reasonably high level. This permits you to make the remaining adjustments
while listening at your own maximum efficiency.
Adjust the separate bass and treble tone controls to correct for the characteristics of your loudspeaker
and for the acoustic characteristics of the room. Choose settings which, in your total system, create the proper
sense of aural balance. Now reduce the loudness setting to a level, lower than the normal listening level in your
room. Note that the full bodied, lifelike quality you experienced at high listening level has disappeared.
This is typical of human hearing since it loses sensitivity to very low and very high pitched notes as the sound
level is reduced. With all other controls unchanged, switch quickly through the four positions of the loudness
contour control until you find the one which most nearly duplicates the full bodied sound you enjoyed at
high level.
Turn the loudness control up to the level at which you wish to listen. The controls are now properly
organized and your system should perform at its very best!
-
ADDITIONAL FEATURES: Turnover Selector Switch includes position which provides correct preamplifier equali
Tape Output, unaffected by tone controls,
zation for tape playback head (requires no extra tape preamplifier)
available to drive tape recording head
Safety Interlock Power Cord disconnects power when cage is removed
Printed circuit throughout, employa dip soldered copperclad laminated phenolic plastic board, easily available
for service- Output level: 10 watts at 3% IM. Peak Power: 15 watts Frequency Response ± 1 db 20.20.000
c.p.s. Hum: Min. Volume Hum: 80 db below 10 watts. Aux and Tuner Hum: 60 db below 10 watts. Phono Hum:
Turnover Control: Tape, RIAA
50 db below 10 watts
Rumble Filter: 6 db per octave cut below 50 cycles
AES, LP -Tube Complement: 2.12AX7, 2.6V6GT, 1.5Y3GT
Dimensions: 12 %" wide x 4%," high x 6%"
deep
Finish: Control Panel: Brushed Copper; Cage and Knobs: Matte Black.
-
-
-
-
-
-
-
$5500
Slightly
higher
in the
wett
WRITE FOR FREE COLORFULLY ILLUSTRATED CATALOG PC -3
harman kardon
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AUDIO
MARCH, 1956
33
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Only recording tapes made
This tape torture test demonstrates the superiority
of magnetic recording tapes made with new Du Pont "Mylar"
Magnetic recording tapes made with Du Pont
"Mylar" last longer, need no special care in storing
-the tape torture test pictured above shows why.
In this laboratory demonstration, tape made with
"Mylar" is run from the recorder into boiling water
and around a cake of ice. Even extreme conditions
such as these cause no change in strength, flexibility,
and dimensional stability of "Mylar ".
Tapes made with "Mylar" contain no plasticizer
... won't dry out or become brittle with age. That's
why these new tapes are ideal for home use, industrial, religious, legal and professional recording.
34
AUDIO
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MARCH, 1956
with new Du Pont MYLAR offer
you all these advantages
i
NO MORE BREAKAGE
Du Pont "Mylar" polyester
film is the toughest of all plas. has a tensile
tic films
strength of 20,000 pounds per
square inch. Under normal operating conditions, magnetic
recording tapes made with
"Mylar" are unbreakable.
4
LONGER LIFE
The high strength of "Mylar",
plus the fact that this remarkable film contains no plasticizer
to dry out or become brittle
with age, makes possible tapes
that last longer. Material recorded today can be reproduced faithfully many years
from now.
NO CHANGE IN DIMENSION DUE
ECONOMY, TOO
The amazing strength of "Mylar" also permits extra -long
playing time, extra economy.
With "Mylar", tapes only two thirds as thick as most ordinary tape can be used, giving
essentially a reel and a half of
tape on one reel.
TO WEATHER
Radical differenirs in temperature and humidity have no
effect on tapes made with
"Mylar ". In radio and TV
broadcasting, timing of programs is unaffected when recorded in one part of the country and played back in another.
NO MORE STORAGE PROBLEMS
Because tapes made with
"Mylar" are unaffected by ex-
tremes of temperature or humidity, no special care is
needed in storage. When completely immersed in water for
a week, "Mylar" absorbs less
than y of 1% of its weight in
moisture.
...
All leading tape manufacturers now have tapes made
with "Mylar" in their line.
Most leading dealers are
featuring your favorite
brand made with "Mylar ".
So -take advantage of
all the important extras
found in tapes made
with "Mylar ". Next time you
see your dealer, ask him for a reel
or two of your favorite brand of tape
made with "Mylar ".
the base material "Mylar" -not finished magnetic recording tape.
"Mylar" is Du Ponts registered trademark for ita brand of polyester film.
Du Pont manufactures
DU PONT
MYLAR
a U PON T
RES. U.S. PAT. OFf.
BETTER
AUDIO
THINGS
FOR
BETTER
LIVING
...
THROUGH
Q
POLYESTER FILM
CHEMISTRY
MARCH, 1956
35
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Preamplifiers and Control Units
EDGAR M. VILLCHUR`
Sound -Chapter 6
A discussion of the reasons for preamplifiers, their requirements and how they fulfill them,
and the circuit configurations that provide boost and cut of either treble or bass frequencies.
phonograph
system is one in which a very high
output pickup is connected directly
to the grid of a power amplifier tube.
Crystal pickups with outputs of 3 or 4
volts, for example, are sometimes used
to drive the grid of a 50L6 output tube
(the 50L6 is designed to operate with
relatively small input voltages) without
intermediary voltage amplifiers.
Normally, however, the output of the
pickup, whatever the type, is fed to a
voltage amplifier. When this voltage amplifier is an extra stage, not used for
other inputs such as tuner signals, it is
called a preamplifier. Magnetic pickups
require preamplifiers because of their
low output voltage. Magnetic pickup
voltages in the range between one and
fifty millivolts are amplified to values
of the order of one volt.
THE SIMPLEST ELECTRICAL
Special Tasks of the Preamplifier
The first job of the preamplifier, as
described above, is to amplify the pickup
voltage, without distortion. Unlike voltage amplifier stages in the amplifier
proper, the preamplifier works with very
small signals. Any stray noise or hum
induced in the pickup, the pickup lead,
Woodstock, N. Y.
IIIII
.
INIOf
20
the circuit components, or the tubes
themselves may compete with the signal
itself in magnitude, at least to the extent of providing an annoying noise
background.
We have seen that FM broadcast
standards for signal -to-noise ratio require that the noise be at least 60 db
down from the signal, that is, that it be
no more than one -millionth of the power
of the signal. When the signal itself is
of the order of a small fraction of a
microwatt the power of stray hum and
noise in the circuit must be kept low indeed in order not to intrude.
One special quality of good preamplifiers, therefore, is that they have very
low noise and hum. Power amplifiers
with signal -to -noise ratios of 80 db (100
million to one) or better are not too
unusual, but we must lower our standards for phonograph preamplifiers, especially when using very low output
pickups.
The next job of the preamplifier is
to introduce the correct frequency discrimination to compensate for the bass
attenuation and treble boost in the recorded signal
equalize the output of
the magnetic pickup. Since all records
have not been made with the same frequency characteristics, most high fidelity
-to
I
ß
E
1
001,1
Fig.
ive
-1.
Resist-
voltage
divider. The input is
attenuated by a
factor of ten (a 10
INFO
to
1
voltage ratio
db), but
there is no frequency
discrimination.
is
1}
1
n
E
ii
6
20
001,1
20
1»
e
FREQUENCY
IN
N.
..
CYCLES PER
ER SECOND
36
preamplifiers have facilities for switching from one type of equalization to
another, shifting the bass turnover and
treble pre-emphasis frequencies, and in
some cases the rate of boost or slope.
These switching facilities may be
fairly simple
single knob with four
or five positions-or fairly complicated,
with separate switching of bass and
treble transition frequencies. Considering the fact that factors beyond the
control of the phonograph operator,
such as microphone position, recording
studio acoustics, and so on, may have a
greater effect on the over -all sound than
the differences in recording characteristics between two companies, it seems
sensible to favor the simpler arrangement. The general tone controls may be
used to 'touch up" the sound to its most
natural form, in any case.
The frequency response of a preamplifier is described by the curve of its
equalization. The excellence of preamplifiers in this respect is indicated by
the accuracy with which they adhere to
the correct equalization curve. It is obvious that describing the frequency response of a preamplifier in terms of
frequency extremes-20 to 20,000 cps,
for example -would tell us nothing useful about the performance characteristics of the unit. What we want to know
is whether the frequency response of
the preamplifier is within, let us say,
one db of the proper equalization at all
points of the curve.
When the desired frequency response
curve of a particular audio component
happens to be flat (as in the case of a
velocity pickup, power amplifier, or
loudspeaker), it is unfortunate that the
meaning of the phrase "frequency response" sometimes departs suddenly, and
a meaningless recitation of frequency
limits takes its place. But it is no less
true here, than in the case of the equalized circuit, that a meaningful description of frequency response must tell us
how accurately the output conforms to
-a
AUDIO
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MARCH, 1956
"BUILD -IT- YOURSELF" AND ENJOY
IN KIT FORM
ID Heathkit
FM TUNER KIT
Features brand new circuit and physical design. Matches
WA-P2 Preamplifier. Modem tube line -up provides better than 10 uv. sensitivity for 20 db of quieting. Built -in
power supply.
Neathkits.
Incorporates automatic gain control-highly stabilized
oscillator- illuminated tuning dial-pre-aligned IF and
ratio transformers and front end tuning unit. Uses
6BQ7A Cascode RF Mage, 6U8 oscillator-mixer, two
6CB6 IF amplifiers, 6AL5 ratio detector, 6C4 audio
amplifier, and 6X4 rectifier.
Shpg. Wt. 7 Lbs.
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Heathkit 25 -Watt HIGH FIDELITY
MODEL FM -3
$2450
AMPLIFIER KIT
Features a new- design Peerless output transformer and K'l'66 output tubes. Frequency
response within ±1 db from 5 cps to 160 Kc at 1 watt. Harmonic distortion only 1% at
25 watts, 20- 20,(X70 cps. IM distortion only 1% at 20 watts. 4, 8. or 16 ohms output.
Hum and noise, 99 db below rated output. Uses 2.12AU7's, 2- KT66's and 5R4GY.
Attractive physical appearance harmonizes with WA-P2 Preamplifier. Kit combinations:
W -5M AMPLIFIER KIT:
W -5 COMBINATION AMPLIFIER
Consists of main amplifier and
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Designed specifically for
=IIIi=1131111Ô1'IÌ1131!Ïry5g
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Heathkit HIGH FIDELITY PREAMPLIFIER KIT
with the Williamson Type Amplifiers, the WA -P2 features
5 separate switch :selected input channels, each with its own input control-full record
equalization with turnover and rolloff controls -separate bass and
treble tone controls -and many other desirable features. Frequency MODEL WA -P2
response is within ±1 db from 25 to 30,000 cps. Beautiful satin -gold
finish. Power requirements from the Heathkit Williamson Type
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Amplifier.
use
t
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Heathkit Williamson Type HIGH FIDELITY AMPLIFIER KIT
This amplifier employs the famous Acrosound TO-300 "Ultra Linear" output transformer, and has a frequency response within ±1 db from 6 cps to 150 Kc at 1 watt.
Harmonic distortion only 1% at 21 watts. IM distortion at 20 watts only 1.3 %. Power
output 20 watts. 4, 8, or 16 ohms output. Hum and noise, 88 db below 20 watts. Uses
2- 6SN7's, 2- 5881's and 5V4G. Kit combinations:
W -3M AMPLIFIER KIT: Consists of
W -3 COMBINATION AMPLIFIER
main amplifier and power supKIT: Consists of W-3M amply for separate chassis conplifier kit plus Heathkit Model
struction. Shpg. Wt. 29 lbs. $4975
WA -P2 Preamplifier kit. Shpg. $69SO
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Wt. 37 lbs. Express only.
Heathkit Williamson Type HIGH FIDELITY AMPLIFIER KIT
This is the lowest price Williamson type amplifier ever offered in kit form, and yet it
retains all the usual Williamson features. Employs Chicago output transformer. Frequency response, within ±1 db from 10 cps to 100 Kc at 1 watt. Harmonic distortion
only 1.5% at 20 watts. IM distortion at rated output 2.7 %. Power output 20 watts.
4, 8, or 16 ohms output. Hum and noise. 95 db below 20 watts, uses 2- 6SN7's, 2- 5881's,
and 5V4G. An exceptional dollar value by any standard. Kit combinations:
W -4AM AMPLIFIER KIT: Consists of
W-4A COMBINATION AMPLIFIER
main amplifier and power supKIT: Consists of W-4AM amply for single chassis construeplifier kit plus Heathkit Model
fion. Shpg. Wt. 28 lbs. Express $395
WA -P2 Preamplifier kit. Shpg. $5950
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Heathkit 20 -Watt HIGH FIDELITY AMPLIFIER KIT
The World's
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This model represents the least expensive route to high fidelity performance. Frequency
response is ±1 db from 20- 20,000 cps. Features full 20 watt output using push -pull
6í.6's and has separate bass and treble tone controls. Preamplifier and
MODEL A -9B
main amplifier on same chassis. Four switch -selected inputs, and
separate bass and treble tone controls provided. Employs miniature
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Shpg. Wt. 23 Lbs.
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Heathkit construction manuals are full of big. clear pictorial diagrams that show the
platement of ea h lead and part in the circuit. In addition, the step -by -step procedure
describes each phase of the construction very carefully. and supplies all the information
you need to as emble the kit properly. Includes information on resistor color-codes.
lips on soldering. and in formation on the tools you need. Even a beginner can build
high quality Neathkits and enjoy their wonderful performance.
AUDIO
in
$3550
Kit Form
HEATH COMPANY
A
Subsidiary of Daystrom Inc.
BENTON HARBOR 25,
MICHIGAN
MARCH, 1956
37
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Fig. 6 -2 (left). Resistor -capacitor voltage divider, and resulting bass boost. Fig. 6 -3 (right). Treble boost circuit.
the ideal (in this case flat) at every
point of the curve.
In summary, then, the preamplifier
must amplify the magnetic pickup output voltage to a value comparable to
the output of the tuner or of a crystal
pickup -roughly half a volt to a volt
without the introduction of significant
distortion or noise, and it must accurately equalize the output of the pickup
to the reciprocal of the frequency characteristic of the particular record. High
quality preamplifiers may be expected
to keep harmonic distortion at a small
fraction of one per cent, to keep the
noise at least 60 db below the signal,
and to provide an equalization curve
accurate within half a db or so of the
theoretical curve, over the entire audio
spectrum.
The preamplifier should also provide
the proper resistance "termination" for
the pickup, as discussed in a previous
chapter.
-
Frequency Discriminating Circuits
-
Frequency discriminating circuits
equalizers for preamplifiers, or variable
tone controls -may be of the feedback
or direct type, but in either case the
basic circuit element is the voltage
divider.
A resistive voltage divider is illus-
trated in Fig.
6-1. If
the series resistor
is 9,000 ohms, and the shunt resistor is
1,000 ohms, as shown, the output voltage
of the network will be just one -tenth of
the input voltage, or 20 db down. Since
resistors do not change their value with
frequency, the same attenuation will occur at all frequencies. The frequency
response of this resistive circuit is plotted in the graph of Fig. 6-1; it can
be seen that the "curve" for output
voltage has not changed from the curve
for input voltage, except that it is reduced in amplitude by a factor of ten.
Now consider the circuit of Fig. 6-2,
ill which the lower arm of the divider
has had a capacitor added in series. At
very high frequencies the reactance of
the capacitor (analogous to a.c. resistance) is negligible -the capacitor acts
as though it were shorted out. The attenuation of the circuit at these frequencies will therefore be substantially
the same as in Fig. 6-1-by the full
factor of ten, or twenty db.
As the frequency is lowered the reactance of the capacitor will increase. It
will begin to affect appreciably the impedance of the lower arm of the voltage
divider, and the ratio of the two arms:
thus it will also affect the amount of
creased progressively until finally, at.
very low frequencies, the voltage divider lets through practically all of the
input voltage, as illustrated in the graph
of Fig. 6-2.
We call such a circuit a "bass boost"
network, but obviously we have really
boosted nothing. What we have actually
done is to attenuate a whole band of
frequencies, and then to selectively let
a part of the attenuated frequency spectrum back in.
The same circuit configuration as that
of Fig 6-2 may also be used for treble
attenuation, by choosing the circuit values so as to shift the entire curve to the
right (upwards in frequency). A treble
boost or bass attenuating network, on
the other hand, must work in an inverse
manner. Application of the same sort
of analysis to the circuit of Fig. 6-3
as was used above will show the reader
why the circuit of Fig. 6-3 can be used
for treble boost or bass attenuation.
The task of providing switching facilities for choosing different turnover frequencies now appears quite simple. All
we have to do is to change the value of
capacitor for each switch position, as is
done in the circuit of Fig. 6-4.
(Continued on page 49)
attenuation.
At some lower frequency the reactance
of the capacitor will be equal to 1,000
ohms, the value of the resistor in the
lower arm. This is taken to be the point
at which the frequency discriminating
characteristics of the circuit take hold
(although it can be seen that the change
is gradual), and is called the transition
frequency. In the case of the circuit under discussion it is the frequency at
which bass boost is considered to begin,
and corresponds to the bass turnover
Fig. 6 -4. Circuit for bass boost equaliza-
tion with provision for changing transition frequency. The capacitors have different values, such that Xc =R at the
desired turnover frequency.
frequency of the recording characteristic.
As the frequency is lowered further
the total impedance of the voltage divider's lower arm increases more rapidly.
The attenuation of the circuit is de-
6 -5. Continuously variable treble
tone control. Equivalent circuits for maximum boost and cut are shown, with signicant elements of that point shown in
heavy line.
Fig.
AUDIO
38
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SMA TUNER
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These highest standards of engineering, manufacture and quality control
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proved in studio and theatrical use, and with an Altec system you are
assured that the components are designed to work together for maximum
performance. Sec your Altcc dealer soon for a demonstration of this or
other Altec high fidelity systems, priced from $324 to $1180.
-is
USA SPEAKER SYSTEM
PROFESSIONAL COMPONENTS CABINETED FOR THE
HOME
35 to 22,000 cycle range
15" woofer
high
frequency driver and sectoral horn
800 cycle
dividing network with balancing facilities
proved components used in thousands of motion
picture theatres mahogany or blond...$324.00
AUDIO
ALTEC FIDELITY IS HIGHEST FIDELITY
Dept. 3-A
9356 Santa Monica Blvd., Beverly Hills, Calif.
161 Sixth Avenue, New York 13, N. Y.
MARC-1, 1956
ALTEC
39
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AmericanRadioHistory.Com
Equipment Report
Munston Amplifier -Preamplifier-Miratwin MST -2D Magnetic Pickup Cartridge- Hermon Hosmer Scott 311 FM Tuner
12 -Watt
to the hi -fi fold who have
begun to collect records since the
introduction of the long -playing microgroove type in 1948 have increasingly
less need for a variety of phonograph
equalization curves in their equipment than
the old timer who has been collecting records for many years. It has long been the
prediction of this observer that when there
was sufficient standardization of recording
characteristics there would appear an amplifier which was designed to accommodate
the basic curve-such as the RIAA has
become, practically -with such other variations as might be required being supplied
by "touching up" with the bass and treble
tone controls. With the introduction of the
12 -watt Munston Amplifier, this department modestly admits, "We told you so."
In all seriousness, however, the design
philosophy of this amplifier offers several
features which make it possible for the
music lover to fulfill his desires for a suitable amplifier at a relatively low cost.
While there is no denying the need for
a wide variety of recording characteristic
curves in an amplifier to be used by the
veteran record collector who has all kinds
of records perhaps dating back to the
twenties, it is equally certain that a collection of LP records can be played with a
reasonably close match of characteristics
provided the amplifier has a properly adjusted phono curve built into it, and suitable flexibility of the tone controls. ADDIO
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has long maintained that exact certainty of
the equalization to published curves was not
the panacea that it would appear to bethere are too many other variables. Carried
to extremes, the "hypercritical" listener
might insist on slavish duplication of all
possible curves. He would then set the controls to correspond to the curve allegedly
employed by the recording company in making the original tape and sit back and
listen, even though the music didn't sound
"right." If we may assume that the listener's system were perfect, this might be
a possible solution. But there is always the
possibility that the monitoring speaker in
the mixing booth could be deficient in bass,
for example, and the engineer would therefore boost the bass in the recording so it
sounded right in his monitoring speaker,
which would make it overbassy in a proper
system. Or perhaps the microphone position
was not ideal, and compensations were
introduced to make it sound like the producer wanted it. In any case, the listener
doesn 't have to listen to it with the speit is not exactly to his likcified curve
ing, he should make changes in his settings
until it is.
The Munston amplifier has only one
phonograph position on its selector switch
a position which gives a medium amount of
bass boost and a fixed rolloff of approximately 9 db at 10,000 cps. On the TREBLE
control, four designations are indicated
peints where the control should be set for
four specific curves. Similarly, the phono
position introduces a fixed amount of bass
boost, and marked points indicate where the
BASS control should be set to give a curve
corresponding to the markings. With this
type of equalization, the listener is encouraged to "cheat " the controls slightly in
the vicinity of the indicated point if he
feels that the reproduction is not perfect-
-if
-
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Fig. 1. (left). Performance curves for the 12 -watt Munston Amplifier. Fig. 2 (below).
Over-all schematic of the Munston.
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AUDIO
40
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
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SIDE VIEW OF
Now you can enjoy real high fidelity record player performance at a
price anyone can afford. The Newest and Brightest "Star" in the high
fidelity firmament is -The Metzner STARLIGHT Turntable .. .
Designed and constructed to combine all the fine features of turntables
TURNTABLE
SHOWING MOTOR
costing much more...
Check these important advantages:
* Rumble better than 40 db. below average level
* Wow and Flutter under .2 RMS
* Built -in illuminated stroboscope
* Silent, fully shielded 4 -pole motor
* Exact speed stability
* Center Drive -No Belts-No Pulleys
*
machined 12" Aluminum Turntable
* 4 speeds
PK from 16 3 to 83 rpm
with non-slip cork pad
P - continuously
variable for perfect pitch
* Built-in hub for 45 rpm records
* Mounted on Lord vibration mounts
* Satin finished Aluminum mounting plate
THE STARLIGHT TONE ARM features: Wrist action head takes all standard cartridges *
Ball bearing swivel * Adjustable counter -balanced stylus pressure * Die cast aluminum construction * 12" long.
STARLIGHT TURNTABLE
$49;0
Y
(Mounting plate
ai,n.nsions 12" x 13N. ")
COMPLETE UNIT
Turntable, Ten* Arm and
Unfinished Birch Basa
$79.50
(Dimensions 16" x 17S§^
x 6h" overall)
DEALERSHIPS AVAILABLE
E
N G
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E
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R
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1041 North Sycamore Avenue
AUDIO
MARCH, 1956
C
O
R
P
O
R
A
T
I
O N
Hollywood 38, California
41
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Fig. 3. Satin black case and brushed brass escutcheon present "decorator- type" a ppearance to the Munston Amplifier.
assuaging his conscience, if he must, with
the excuse that "The knobs are probably
not set right anyhow."
The response curves obtainable from the
unit in the phonograph position are shown
in the upper section of Fig. 1 over the
range of indicated curves-further equalization may be obtained by going beyond
the indicated points, both above and below
the shaded portion. The tone -control action
-in reference to any of the three highlevel inputs -is shown in the center section,
and the IM distortion is shown in the lower
section. Figure 2 shows the schematic of
the amplifier, and Fig. 3 portrays the external appearance of the unit, which measures 11% in. wide by 9% in. deep by 4 in.
high.
Performance
Sensitivity of the amplifier is relatively
high, with an input of 2.4 my giving the
standard 1 -watt output on phonograph, and
an input of 25 my giving the same output
on the high -level inputs, both with the volume control at maximum. Hum and noise
was measured at 66 db below 1 watt at
normal settings of the volume control and
with the tone controls flat. Strangely
enough-but a plus feature rather than
minus-the hum and noise measured the
same whether at phono or high -level settings of the selector switch, both inputs
being shorted.
Three phono input jacks are provided
accommodating both low- and high-level
magnetic cartridges and crystals or other
amplitude-responsive pickups. Three high level jacks accommodate tuner, tape, and
auxiliary inputs, as indicated on the selector
switch. 4 -, 8 -, and 16 -ohm outputs are provided, and the amplifier is stable with
practically any type of output load. Power
consumption is 62 watts at the 1 -watt output.
For the music lover who is looking for a
-
maximum of simplicity and sufficient ease
of operation that the distaff side of the
family can soon learn to feel comfortable
with the "system," the new Munston seems
to be a practical answer, for it does give
good listening quality and it is easy to operate. Added to this is a neat brushed brass
escutcheon fronting a satin black case
which provides adequate ventilation and
furnishes the is for the beauty that
M -21
MIRATWIN MST-2 MAGNETIC
PICKUP CARTRIDGE
The uniformly high quality of magnetic
pickups already on the market might well
seem to act as a deterrent to any manufacturer who might contemplate introducing another, but the new Miratwin was
introduced nevertheless, and is likely to entrench itself firmly amongst the others because of some of its features.
The Miratwin -built by the manufacturers of the Miracord XA -100 record
changer and the Miraphon AM-110A manual record player-conies in two types,
depending on the styli supplied. The
MST -2A is equipped with two sapphires,
and the MST -2D is equipped with a sapphire stylus for standard grooves and a
diamond for microgrooves. Both models are
otherwise identical, and consist of two
electrically and magnetically separate units
permanently mounted back to back, as in
Fig. 4, and carried in a mounting that
switches electrical outputs as the pickup
assembly is rotated so that the leads from
the pickup housing do not twist back and
forth with rotation of the pickup. A separate connecting lug on the mounting permits grounding the frame through the usual
third pin on the pickup housing.
The stylus assembly of each of the pickup
,units may be removed easily using only
one's fingernails, and when replaced is
seated accurately because of a locating tab.
Thus the styli can be changed easily by the
user without the need for returning the
Fig. 4. The new
Miratwin magnetic pickup
pickup to the dealer or factory. The stylus
shoe has sufficient vertical compliance to
prevent damage in case the pickup is
dropped on the record.
As should be expected from a high -quality pickup, response is flat within +2 db
from 20 to 18,000 cps on LP Vinylite
records, and from 20 to 222,500 cps on
shellac 78's, using the correct stylus for
each, the usual increase in the high end on
shellac pressings is, of course, due to decreased compliance of the record material
over the softer Vinylite.
Using a Cook. Series 10 test record with
a stylus velocity of 9 cm /sec at 1000 cps,
the output of the LP side was measured at
49 millivolts, which matches the advertised
claim for 55 my at a 10 -cm /sec stylus velocity ; similarly, measured output for the
sane record using the standard stylus was
41 my -both values being relatively high.
With the microgroove stylus, a peak of
al .out 1.1 db was noted at 17,000 cps, and
output was down 3.3 db at 20,000 cps,
the highest recorded on the Cook disc. Inductive hum pickup was almost unmeasurable -being of the saute order of magnitude
as that usually found with moving-coil
types with impedances of the order of 2
ohms or so. No condition could be found
where hum picked up from the phonograph
motor could be heard in the loudspeaker
with amplifier controls set for normal program output. Yet the impedance of the
Miratwin is approximately 1450 ohms on
the LP side, 910 on the standard. This is
eomposed of inductances of 385 and 248
unillibenries for LP and 78, respectively,
and resistances of 1400 and 875 ohms for
the two sides. Stylus compliance is stated
to 4.2 x 10 -6 cm /dyne, which is about normal for a high-quality magnetic pickup,
and effective mass is listed at approximately 3 mg, which is also about normal.
Mounting is simplified by the construction of the cartridge, which is held in the
"chassis" by the shaft of the turnover
knob. The entire pickup assembly can be
removed from its holder by pulling the
knob and shaft out, allowing the unit to
be lifted out and giving access to the
holes for the mounting screws, which are
furnished. Slotted holes in the holder pro
cide some latitude in mounting.
The Miratwin tracks without distortion
up to stylus velocities of 20 cm /sec (the
highest levels of tones available on discs
for testing) and shows no audible distortion of records with stylus velocities as
high as 28 cm /sec. Needle chatter is desirably low, and there is no apparent magnetic
pull exerted against a ferrous turntable to
increase stylus force when only one record
is between stylus and platter.
The cartridge has a total weight of 18
grams, and a load resistance of 50,000
ohms is recommended, resulting in a practical limit of 200 µµf for the connecting
loads -which means about eight feet of
the usual low -capacitance microphone cable
(25 µµf /ft). The recommended stylus force
for changers is 8 grams, reducing to 6
grams for manual turntables with high quality arms.
The instruction booklet supplied with
each Miratwin cartridge includes a serially numbered machine -run response curve showing output at eight frequencies resulting
from actual measurements, thus showing the
user what he has a right to expect from
his pickup.
With the relatively high output and very
low hum pick -up, the Miratwin cartridge is
especially well suited for any installation
where a strong a.c. field has been causing
trouble, but on the count of listening quality alone it must be considered one of the
(utter- quality magnetic pickups.
-
cartridge.
M-22
AUDIO
42
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MARCH, 1956
it's the `guts' in the P4.101.1 chassis
that make the critical difference
Over 35 years
leadership in Electronics
PILOTONE AMPLIFIERS
Of major importance in the performance
of a high fidelity amplifier are its component
parts: the condensers, resistors, transformers
especially the transformers and above all,
the output transformer.
All transformers look alike in the schematic
but that's where the similarity ends. This is one
case where `a boy can't be expected to do a
man's job'. No puny output transformer-however imposing the outer shell -can serve a good
high fidelity amplifier without introducing distortion. It takes plenty of 'iron'-not to mention
special winding methods -for an output transformer to handle the power output cleanly.
Inspect the Pilotone amplifiers-all 5 of them
-and compare them critically with the others
in the field-regardless of make, power rating
or price. Notice how much heavier the output
transformers in the Pilotone amplifiers actually
-
-
-
are. Even the power transformers how much
cooler they `run' in operation. Observe also that
the Pilotone amplifiers employ known brand name condensers and resistors generously rated
to provide wide margins of safety against
failure and breakdown.
After all, tubes are tubes and sockets are
sockets, but it's the `guts' in and on the chassis
that make the critical difference in performance. If you look for these things when you
choose your amplifier, we know that -like many
others -you too will select one of these Pilotone
amplifiers for your own home music system.
PILOTONE AMPLIFIERS
AA -410.. $54.50
AA -420 .. $99.50*
AA -903.. 69.50*
AA- 904.. 99.50
AA -905 (illustrated) ..$129.50
Metal amplifier covers
each 4.95
with built -in Preamp
NOTE: Prices slightly higher West of Rockies
-
your dealer for a Pilot Hi -Fi Demonstration For complete literature on
Pilotone Amplifiers, Pilotuners and other high fidelity units, write to: Dept. GC -1
See
the
,UDIO
ot
RADIO CORPORATION
37 -06 36th STREET, LONG ISLAND CITY 1, N. Y.
MARCH, 1956
43
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SCOTT 311 FM TUNER
Practically- any good FM tuner on the
market for home-music -system use now
boasts of a sensitivity that would have
been impossible five years ago, so that it is
no longer enough that we say that " such and -such a tuner has a sensitivity of less
than five microvolts" to make it a good
buy. Sensitivity it must have, of course,
but that is almost taken for granted. More
important is the quality of reproduction,
the freedom from drift, and the reliability
of performance.
Hermon Ilosmer Scott has always had a
reputation for making fine products, and
even though the 311 FM tuner is low priced
-in comparison with other Scott tuners
turns in a performance and quality report
that is enviable. Sensitivity is claimed to be
3 itv for 20 db of quieting; automatic
gain control applied to the r.f. and first i.f.
stages maintains uniform output over a
wide range of input signal intensity; wide band design ensures drift -free reception.
Following the publication of two papers
from M.I.T. a few years ago, several manufacturers have reduced the findings of the
laboratory to practical and manufacturable
designs. To improve the tuning characteristics of FM receivers and to reduce the
necessity for micrometer adjustment of the
tuning for optimum sound quality, a wide band ratio detector circuit-the subject of
one of the M.I.T. papers -is employed in
the 311. The detector circuit has a bandwidth of some 2 megacycles, following an
i.f. amplifier with a 150 -kc pass band. Thus
the i.f. amplifier is the governing factor
with respect to selectivity, and minor variations from the absolute center of the discriminator pass band do not cause a degradation of quality. With this type of
circuit, the selectivity can be considerably greater than with conventional circuits, if properly engineered, and there is
no recurring signal from stations which are
-it
Fig. 5. Hermon Hosmer Scott's new 311 FM Tuner is compact, mounts in an opening
4 1 /16 by 121A inches, and is 8t/2 inches deep.
"detected"
on the returning slope of the
discriminator curve. This results in a true
"one- spot" tuning which is not particularly critical. With a sensitive tuning meter,
the set becomes as simple to tune as the
garden- variety AM radio.
The Scott 311 tuner, shown pictorially in
Fig. 5 and schematically in Fig. 6, is of
simple, if rather modern, styling. The panel
is gold finished, the tuning dial is of transparent plastic with white lettering, and is
illuminated internally, and the dial index
pointers are of red plastic. The large outer
knob is directly coupled to the tuning capacitor shaft for fast rotation, while the
smaller knob is a vernier for fine tuning. The
tuning meter is very sensitive, and because
of its low damping the optimum tuning is
located readily. The gold -finish knob at the
lower left corner of the panel controls a.c.
power and volume
the output were to be
fed to a control amplifier, this control could
be used only for level setting, with a.c.
-if
a.
rs
n.
power being controlled from the other unit.
The tuner may be mounted in the user's
own cabinetry, or may be housed in a metal
accessory case for table -top or bookshelf
use. It combines neatly with the Scott
121 -B Equalizer -Preamplifier, as both have
the same size panel and the same styling.
As will be noted front the schematic,
the tuning meter is located in the plate circuit of the first tube -which is a cascode
r.f. stage -and the a.v.c. voltage is fed to
this tube from the limiter circuit. While
most tuners employing the ratio detector
do not also employ limiters, this is usually
an economy measure, for when limiters are
used -there are two in the 311 -the ratio
detector performs admirably. Because of
the wide -band detector, there is no need for
automatic frequency control, and with
temperature- compensated circuitry there is
a minimum of drift anyhow. Under test, the
tuner was set to a New York station at the
beginning of a week and properly tuned
when the set was fully warmed up. Thereafter it was turned on and off daily for
seven days with no further adjustment, and
the station remained perfectly in tune with
excellent tone quality.
A practical test of sensitivity is shown
by satisfactory reception at our Long Island location from WNHC in New Haven
distance of approximately 55 miles and
at an angle of 120 deg. from the main axis
of a TACO six -element FM Yagi antenna.
This seems to indicate a completely satisfactory sensitivity and stability, for the
station was received consistently several
evenings in a row.
As is usual with modern tuners, the 311
is self powered, using a 6X4 rectifier and
adequate resistance-capacitance filtering.
The tuner circuit uses a 6BQ7A as a caseode r.f. stage, a 6U8 as oscillator-convericr, three 6AU6's as i.f. amplifiers and
limiters, two crystal diodes in the ratio
detector circuit, and a 12AU7 as audio
amplifier. Considerable "flat" feedback
is applied over the audio stages to provide
a low- impedance output, permitting the use
of a relatively long connecting cable, if
necessary, without high- frequency attenuation.
From a practical standpoint in day -today use, the 311 tuner appears to have performance which belies the simple appearance of the chassis and panel, and is quite
likely to surprise anyone who studies its
characteristics closely.
M -23
-a
s.
.
c+..
c.+..
Fig. 6. Schematic of the Scott 311 FM Tuner.
AUDIO
44
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AmericanRadioHistory.Com
MARCH, 1956
FIRST ANNOUNCEMENT -NEW SONOTONE SPEAKER SYSTEM
It gives you
not only "presence"
-but "absence "!
Any truly good speaker system gives
you "presence" -the feeling that the
music is being created right in the same
room. But this new Sonotone system
gives you absence, too. Gone is all
awareness of "loudspeaker sound ".
There is nothing between you and the
music.
The Sonotone Linear Standard
Loudspeaker System utilizes the most
advanced type of speaker damping
true acoustical damping. This, together with the highly flux -damped voice
coil, gives astonishing "transient- true"
response. You hear each instrument as
separately as in the concert hall. Technically, this system is so "linear" it can
be used as a laboratory standard!
-
THE SONOTONE LINEAR STANDARD SYSTEM uses the superlative new
Sonotone CA -15 fifteen -inch coaxial speaker, mounted in an enclosure
of latest design engineered to enhance the speaker's unique smoothness and accuracy. Cabinetry is in the tradition of fine furniture,
meticulously detailed and finished.
UNIQUE,
ELLIPTICAL CONE
TWEETER
EXTREMELY HEAVY
MAGNET ASSEMBLY
LINEAR OUTPUT,
20 TO 17,000 CYCLES
CA -IS COAXIAL SPEAKER has a huge 5 -Ib. Alnico V magnet, with 15,000 gauss
flux density. Unusual velour suspension of the ridged, curvilinear cone drops resonance to
30 cycles, keeps extreme "lows" full, rich and natural. The six -inch non -metallic cone
tweeter is elliptical, providing wide lateral dispersion of "highs" without tinniness or piercing effect. 25 watt output, 40 watt peak. Woofer and tweeter also available individually.
SONOTONE
Prices and specifications are subject to
change without notice.
A
IMO
MARCH, 1956
45
www.americanradiohistory.com
AmericanRadioHistory.Com
BN.
JEAN
He had made a pile in the pop market but
in traveling around the country, and especially on some late night turnpike drives,
he had come to the conclusion that the
wise record company was one which could
get into the jazz field while the getting
was still good.
The only trouble is that he knows nothing about jazz and will no doubt get
burned several times before he either drops
the idea or hires someone competent to
judge talent for him and who knows jazz
itself. A company about to go into the
serious music field would never dream of
entrusting its catalog to the same personnel
who worked in the hit -picking department
on the pop side. Yet many of them do just
that with their jazz catalog and then
"This
SO IT
Look
is Jean
LIKE.
.J.\ZZ is
Shepherd -we have records ..."
at lung last still sloes ill nuuty a;n, -in the radio
really becoming respectable. In fact,
so much so that many of the nation's
radio stations are now putting jazz into the
same classification as "serious" or "classical" forms of music. The transition hasn't
been completed yet but the signs are strong
that things are happening. True, there is
still a great deal of confusion as to the
nature of jazz and how to program it, but
the day is not far off when most radio
stations will make extensive use of jazz
library. In a way, this has an ironical twist
since radio through the years has done
very little to aid the cause of jazz and has
in many instances done just the opposite.
By allowing the song pluggers and publishers early in the game to take over much
of the programming of music shows other
than those what were strictly classical, the
air became little more than an extension of
the juke box in the local bar. This merely
added to the confusion about jazz since
many intelligent people began to believe
that the products of Tin Pan Alley and the
local disc jockey were jazz and they wanted
no part of it. Because of this mixup jazz
was -and still is, to a large extent -lumped
in many minds with fan clubs, Joni James,
and rock and roll. And speaking as one
who has had some experience in the field,
listeners were not the only ones suffering
under that delusion. It also existed -and
ABOUT MR.
"This is .',on Shepherd -we have records
" Seven nights a week on WOR
New York) we hear those words, sometimes at 12:30 a.nt. and sometimes at
1:00 a.m. when his program starts. And
eve hear then again at station breaks all
night long until the cold gray dawn hour
of 5:30, when the more enterprising souls
are getting started on their daily grind
and others of us are just getting home.
'Tweren't always thus. We first heard
Jean on Saturady afternoons 'way last
Summer, and all through the Fall except
when some amateur sporting event known
as football pushed him out of his accustomed time slot -which was from 3:00
to 6:00. But we heard enough.
Enough, that is, to realize that here was
a man who talked about Jazz without
sounding as though he were something
apart from us common people who have
not been touched by the mugie wand of
the licorice stick -those of us who believe that it is possible to enjoy jazz without having to "understand"
without
having to see the social significance of
each note, each subtle phrasing. You know
it-
the kind of people we mean -the same
kind that can enjoy Tschaikowsky or Bitch
or Kodaly or maybe even Copland without
a Mus. D.
Anyhow, we finally decided that Jean
was the right man to write about jazz
for Avow readers, just as we thought that
station itself, stemming from the disc jockey
right down to the record libraritin. But the
old order is slowly changing and more
and more jazz is being placed in its rightful slot. Evert the most hidebound of radio
program directors are sneaking an occasional glance at the record review columns in such admittedly respectable journals as The Saturday Review, Harpers,
and The New Yorker, and are beginning to
wonder whether they ought to take a couple
of those new LP's home from the library
and give them a closer listen. Perhaps they
might even allow a few of them to get on
the air sandwiched between the Crew Chiefs
and the inevitable Joni. For example,
WQXR -long famed as the good music station of New York-has added a weekly
show devoted to jazz. True, the show is only
forty -five minutes long and is stuffy and
pedantic, but clearly their heart is in the
right place. Another chink in the wall occurred when NBC contracted to put many
jazz remotes into the programming of the
weekend show "Monitor," and as a result
most of good reviews the show has received
specifically mentioned the outstanding
music they were airing. This has not gone
unnoticed in the trade.
A few days ago, I talked to a record
company owner who was frantically trying
to line up some jazz artista for his label
SHEPHERD
Edward Tatnall Canby- was the right man
to write about the classics when we heard
him on the radio back in '47. And here is
what Jean has to say about himself:
"I was spawned in Chicago at about the
time Louis Armstrong joined King Oliver
to make jazz history there. Biz Seiderbecke was playing club dates with Muggsy
Spanier as a cornet duo. I have oscillated
sympathetically to jazz ever since.
"Prior to World War II, while attending Indiana University, I jobbed around
my native heath accompanied by a somewhat eroded bass fiddle which provided n
means of attaining social success as well
as tuition. After a three -year stint In the
Signal Corps where I was kept in the
lowly rank of corporal by jealous commanding officers, I was discharged by a
grateful country and was free again to
plague entertainment -loving radio listeners."
Since that time Shepherd has become n
well known, if not yet well -beloved, radio
raconteur of jazz, fine wines, sports cars.
ash blondes. and pinochle. His "shows"
have emanated from Chicago, \VLW Cincinnati, KY1V Philadelphia, and the
Mutual Network. Ile has written for many
technical as well as literary journals. A
long -time audio buff, he is also a rabid
amateur radio addict currently holding
the call K2ORS. We're glad to have him
aboard.
;6
wonder why the sides they cut are ignored
by jazz buffs. One thing they do, though,
is to make the job of reviewing much
rougher through sheer quantity of output.
The days are gone when four or five singles
a month was the normal output in the jazz
catalog of the average label. And by singles, I mean 78's. Today they arrive in
coveys by every mail and under all sorts
of incredible labels. Many of these labels
exist only for that single LP and are never
heard from again, while others are usually
found in the bird -call lists but are now
taking the plunge into esoteric jazz. It
glows wonderfuller and wonderfuller.
But like I said it makes for a slow track
in the reviewing department. About all the
reviewer can hope for is not to slight a
really worthy disc because he didn't have
the time to give it a proper chance on the
turntable. Most LP 's carry from 30 to 50
minutes of material these days and if a
person has fifteen or twenty discs to review
in a week it is easy to muff a good thing
from time to time. Not long ago I had Billy
Taylor, the highly literate jazz pianist, on
a show of mine and we got on to the subject of record reviews. He said that almost
every disc made today contains some material that could best be described as
"fill," put on the record just to fill out the
allotted LP time. By that he meant that
an artist will intersperse with his best
material a few items of lesser interest. He
went on to say that he realizes many reviewers make a practice of listening to
just a couple of cuts on any given disc
when they are under the press of time to
review a lot of stuff and that he lives in
deathly fear that they will happen to hear
only the so- called "fill" material when
they are about to pass judgment on his
recorded work. The quick answer to that
one, of course, would be to never record
secondary material, but such an answer
would overlook good production techniques.
A
practiced and discerning recording artist
of today looks upon an LP as an actual
forty-minute performance and he expects
to be listened to in that manner. So lie sustains interest by varying his material skillfully so that he does not tire the listener
by keeping him at an emotional peak. In
the old days, a band would come into the
studio and record four or five of their
best things which could then be released
at the discretion of the company, but always singly. This worked in favor of the
artist in many ways since his material
usually had a fresh sound only because the
discs came through so widely spaced. A
good case in point is the recent release by
Columbia of a large collection of Benny
Goodman masters under the title "BG -25,"
in reference to Goodman's 25th Anniversary on records. Most of the individual
itenis had been released earlier as singles
and had enjoyed tremendous commercial
success, but when lumped together they
have a sameness of sound and conception
that is, at least to me, rather monotonous.
AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH. 1956
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MARCH. 1956
47
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Nostalgia and its effect on critical values
will be the subject of one of these columns
in the near future. In fact, there is so
much to he said on the subject of nostalgia
and what it does to usually logical and
level- headed critics that I rut almost afraid
to tackle the problem in a magazine rather
than in a set of morocco -bound volumes.
It closes many an ear to the world around
Announcing England's
if.
First Public High Fidelity Show
Speaking of the world around us, a
couple of unusually good discs can be heard
reflecting a few contemporary sounds. And
while just getting my feet wet, sò to speak,
in the columns of an otherwise august
magazine, here are a few that come to mind
this month:
The Jo Jones Special Vanguard VRS -8503
Stone of the best Basle l:hyt hot ,ouuds to be
recorded in years. Jones. of course, is one
of the really great drummers and was never
better than on this tine LP. Basle himself
appears on several cuts and once again demonstrates how rare a thing a good ensemble
piano really is. Ile drives a group as though
he lad a bullwhip in his left hand and a .45
in the other.
Tangents in Jazz -Jimmy Guiffre
Capitol T-634
A very unusual and highly cwnmendnble
offering showing the latest work of a young
and talented West Con st performer in the
person of Guiffre. It is interesting to compare
this material, all Guiffre originals, with his
earlier work with the IIernian bands. On this
disc, according to the copious liner notes,
Guiffre attempts to dispense with the usual
usages of the rhythm section and instead use
it as "punctuation" for the work and lines of
the soloists. Don't presume that this technique
does away with the beat on the contrary it
seems to be as strong as ever. By the way,
Guiffre writes with rare humor and grace.
This recording has been much listened to by
contemporaries of Guiffre and already his influence can be heard in other groups. I recommend this disc without qualification both as
to content and for technical excellence.
;
/
Washington Hotel Curzon Street, London, W.1.
Friday, Saturday, and Sunday
April 13th, 14th and 15th
11 A.M. to 9 P.M.
-
Approximately 40 exhibitors representing England's
leading manufacturers of fine audio equipment
will conduct continuous demonstrations during show hours.
-
American high fidelity enthusiasts and representatives
of American manufacturers planning to be abroad
at that time are invited to attend.
-
-
For further details, write to The Secretary
LONDON AUDIO FAIR 1956
17 Stratton Street, London, W.1.
Thelonious Monk plays the Music of Duke
Riverside RLP 12 -201
Ellington
Monk is one of the most controversial of
present day musicians. He was one of the
pioneers of the contemporary forme of music
back in the early 1940's along with Gillespie
and l'arker, but his personal characteristics
prevented his fame from spreading nmch
beyond a small circle. Admittedly very influential among pianists of the present day,
he has never been recorded too well. On this
disc he appears with two excellent confreres
in the persons of Kenny Clark (drums) and
the admirable Oscar Pettiford (bass). Ile
plays with a sort of acid poetic humor that
always swings and is highly individual. If
certain of his stylistic manners remind you
of others, it is well to remember who came
first. As we said, he has been very influential among younger artists. This is a most
enjoyable recording and one worth owning.
Technically good, too.
Rudy Braff Special Vanguard VRS -8504
Braff is a sort of throwback in today's
world of highly trained technicians. IIe Is
a trumpet player of much drive and a kind
of rough plaintiveness at times reminiscent
of the best work of Bonny Berrigan, and
who is famed among musicians for his inability to read music. On this disc be has the
assistance of some exceptionally good men,
particularly Vic Dickenson and Jo Jones.
This recording is a good example of correct
casting in that the musicians were carefully
selected to give complete consistency.
This month we haven 't tried to review
everything currently available but have
instead picked a few of the outstanding
discs of more than usual interest. However,
in future columns I intend to cover as much
new material as space will permit, eliminating only those recordings that seem not
acceptable to a serious jazz fan.
AUDIO
48
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
PREAMPLIFIERS
(from page 38)
Controls
The fixed equalizers which have been
so far discussed are designed to compensate for known frequency curves built
into the record. There are also many
Tone
conditions affecting frequency response
which are not known beforehand by the
circuit designer. These include room
acoustics (discussed in more detail in a
later chapter), deficiencies in associated
equipment which may unduly boost or
attenuate portions of the frequency
spectrum, changes in over -all volume
which change our bass hearing sensitivity, and variations in program material
caused by differences in microphoning,
studio or hall acoustics, and so forth.
We cannot hope to compensate accurately for all such conditions, but flexible tone controls, intelligently designed
t, approximately correct for conditions
typically encontered, can help a lot.
These tote controls work on the same
principle as the frequency discriminat-
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Fiu.
heavy line.
jug voltage dividers discussed previously,
with the difference that the rate of boost
and cut, or the transition frequencies,
or both, are controllable.
Figure 6
illustrates a treble tone
control, and the equivalent circuits for
maximum treble -boost (slider at the top
of the potentiometer) and maximum
treble -cut positions (slider at the bottom of the potentiometer). Figure 6
illustrates a bass tone control, also with
equivalent circuits for maximum bass
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7'he effectiveness of a tone control is
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affords accurate compensation for varying conditions. It has been the writer's
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front the audio spectrum mid- point, say
(Continued on page 67)
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49
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EDWARD TATNALL CANBY`t
trills
WALTZ TIME
Bonbons.
(Waltzes,
Polkas,
Marches, Galops by Johann Jr. and Josef
Strauss.) Vienna State Oper Orch., Paulik.
Vanguard
VRS
459
The waltz pie can be cwt into a fascinating
variety of slices via LP! This is a good title.
for it suggests Just what the record is,
though perhaps not its full interest as an excellent performance of a raft of unfamiliar
Strauss In the good old Strauss idiom. Only
a handful of these will be already in your
mind's ear -but most will soon memorize
themselves, and to heck with fame and popularity! Wonderful stuff, played to perfection
in Viennese style in Vienna.
The recording is in the hi-fl manner, close up in a good resonance, with a hard edge,
somewhat exaggerated triangles and the like,
plenty of big, thumpy bass. Not too unsuitable for this sort of music, which should get
away from the "concert ball" type of sound
anyhow.
(Note: See also \'RS 457, similar.)
Portrait of the Waltz. Philharmonia
Orch., Markevitch.
Angel 35
A
This is no background disc. Rather. it re
quires a good deal of straight Imaginative listening and is worth it too. The title, sober minded, again is a good one. The idea is to
offer a program of music embodying the widest range of penetration of the waltz idea
itself -from the almost tearful seriousness of
Liszt, to the rollicking trifles of Mozart's
"Sleigh Ride ;" from Stravinsky's raucously
pleasant little waltz from his Second Suite to
the sweetness of Berlioz and the "Valse
Triste" of Sibelius, and a big noisy piece by
Busoni.
The playing is intense, rather fast, not too
often relaxed, wonderfully accurate, the contrasts from piece to piece skillfully planned
and dramatically carried out. Sound is big,
distant, in the now familiar Angel (EMI)
mnner, remarkably unlike the hi -fi Vanguard style of microphoning above. Surfaces
_o
rgeons.
quality the same.
Strauss Paraphrases, (Waltzes arranged
for piano). Edith Farnadi, piano.
Westminster WN 18064
Piano paraphrases of the waltz have always
into the jazz and cafe era.
Many a big pianist is virtuoso has fixed himself
up with scintillating showers of waltz -time.
to show off his own prowess in a pleasing
manner.
These are mainly of the ultra-flowery kind
that go back to the influence of old Liszt,
and they represent a technical challenge of the
most appalling difficulty. They don't come
ver very well here. As played by Fa rnadi, the
been popular -even
YOUR OWN
BE
Vienna
RECORD CRITIC
Choice of LP records for three
best reviews sent in each month.
Simple as that! just write your own
review on the record selected by Mr.
Canby for the "Problem of the Month,"
send it in, and perhaps yours will be one
of the fortunate three chosen by the
judges. If your review is first, you may
select any three records reviewed in this
issue; if yours is second, you may select
two the third choice may select any one
record. Your selections will be shipped
to you postpaid at no cost to you.
Each month, Mr. Canby will name one
record as the "Problem of the Month."
Listen to it, study it both as to music
and as to recording quality. Then write
a brief review on a postcard -no other
entries will be considered -and send it
to AUDIO, Dept. RR, P. O. Box 629,
Mineola, N. Y. so that it arrives on or
before April 2, 1956. Winners will be
announced in the May issue, and the
review chosen as first will be published,
along with Mr. Canby's own review, in
the same issue.
For this month's problem, Mr. Canby
selected:
has
Stravinsky: The Firebird (complete
ballet) L'Orchestre de la Suisse RomLondon LL -1272
ande, Ansermet.
it, borrow it, or just listen to it
somewhere -then tell us what you think
about it.
Buy
RULES
1.
_
and sions of the Judges are final
I
utrirs or choices of the Judges.
:r i laws of the selected record must
mined un
will
:S.
1.
and no cur -
will to entered into regarding
,- ya,ndence
a
be subs
government postcard. No others
siderei.
Only onettenlr) will
be
be considered from each
contestant.
All entries are to b, "m.0 the pr, rIv .d
i.
tei
1(5(110 Magazines, Iu,
I
first will be mild:rvit Ike list of r
Eas
.,.
1.
tI,!
Canby in the issue
Ord" Is announced, thy writer of 'ti
irischosen as first will be given the,:
if
his
chosen as
choice:
e
nd
the
will
be
writer
of
the
O.
Entri,', will
be
r
given two reier
lila ekolcr: the writer of the review
a
third will be glven One record
judged on the
and ornaments and flourishes all but
drown out the basic waltz music itself.
I can think of two relisons. One, perhaps, is
acoustical: the recording is on the dry side
where, it seems to nie, it should have been as
big and golden and liquid as the engineers
could make it. These are old -fashioned transcriptions (arrangements), period pieces of
another day, and they need an appropriate
acoustical setting. The dryness brings out the
detail work too prominently, showing tip the
musical seams in a harsh light.
Secondly, (or firstly if you will), Fernadi
plays with an ultra -modern, dry technique
that in itself accounts for a lot of the trouble.
She plays all the notes and easily, but the
music is drowned in then). Too much preoccupation with the flossy ornament- admittedly tough to play -and not nearly enough
with the waltzes themselves.
This stuff can be played effectively, even
today. But I don't feel that this disc does
the job-
FOR THE CURIOUS BROWSER
Gilbert 8 Sullivan: Princess Ida. D'Oyly
Carte Opera Co., New Symphony Orch.,
London XLL 1200 1201 (2)
Godfrey.
Another l)'l)yly Carte London G & S' What
more need be said?
A lot, come to think of it. "Princess Ida" is
one of the rare operas, traditionally seldom
heard --and like so many works of this sort, it
also, traditionally, has some of the finest of
all Gilbert and Sullivan music (and rhyme)
in it. Why does this so often happen? There's
no accounting for the opera stage.
But LP, as we all know, makes up for these
oddities and caprices of popularity and there's
now no excuse whatsoever for you to avoid
the very hest Gilbert & Sullivan of all. Come
and get it.
I Mined -and this is also the usual thing in
such cases -this strikes nie as a particularly
Intense and able performance by the famous
IYOyly Cartes, as though it were a relief to
do this less -common opera, for a big change,
instead of endless Mikados and Pirates and
Pinafores, ad inf. The company seems to rise
unanimously to the manifest superiorities of
this music in many a spot and the results are
splendid, no less.
The recording is splendid, too, big, fat,
round, realistic, undistorted, with marveleous
presence. Listen to the beginning of Act II,
for example, with the chorus of females ut
the female academy of learning commanded
by the redoubtable heroine, Princess Ida herself. It'll make you blush with sheer joy.
(Note that there's it single LP of highlights from the opera, for those who want 'em.
Me, I wouldn't settle for less than the works.)
,
Steel Band Clash. (Music for steel band
from Antiguo, recorded on location).
,
I.
musical and technical accuracy. N.
form will not count, but the n viie
the opinion of the Judges, be LItli,
legible to be read easily.
Cook 1040
elitl.
780 Greenwich St., New York 1.1, V. Y.
Sequel to Cook's earlier "Brute Force" disc,
that one named after one of the oil drum
AUDIO
50
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
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ÉÖOK!
bands, which also plays here. A fine hi -fi record and there's reasonable variety, too. even
for outside ears. Cook's "15 kc crickets,"
under somebody's West Indies porch, are
nearer 8000 cps, I'd say, but they do add an
REPRODU( ER E ARM
exotic touch of realism. Not as much singing
in this as In the previous disc.
Note that the record is pressed by the new
powdered vinyl Microfusion process. It sounds
it-super hi -fl and with superb surfaces.
Beautifully Finished in Gold and Silver Tones
r
Folk Songs with the Trapp Family Singers.
Dr. Franz Wasner, conductor.
Decca DL 9793
Here is the familiar Trapp format-groups
of Austrian songs, instrumental yodels, splicer)
a sonata or suite or two for recorders
and harpsichord ; this Is the latest in n considerable series of records. It's memorable.
though, first because it may be the Trapp
last disc, (according to hearsay, they are disbanding) and secondly because of its extraordinarily tine recording.
The small choir of voices is so ultra -realistic that you can virtually pick out each person and place him or her in the Imaginative
ensemble. Old friends will quickly spot an unfamiliar voice or two in the current group,
and can almost name the others, one by one.
The finest small- chorus recording I've heard.
and the instrumental interludes are as good,
in their way. The singing is up to the usual
warn, modest but highly professional Trapp
standards.
with
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Monteverdi and Marenzio: Madrigals on
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Here are parallel madrignl settings of the
same texts by two famous composers of the
14
GRAMS
GRAMS
7
Denotes conventional type high fidelity arm
The above comparison was made in a Leading Laboratory using the McPROUD
method of test, i.e., Placing a 45 Record on a Turntable so that the edge of the
/4" eccentricity
record hole touches the Turntable Spindle. This results in a
of the record. Tests made using G.E. and Pickering 350 Cartridges.
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Tuskegee Institute Choir. Spirituals. Conducted by W. L. Dawson.
Westminster WM 18080
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turn of the 10th century in Italy, Marenzio in
the earlier style, Monteverdi already, in his
highly original way, tending towards Instrumental music and operatic drama. A most
interesting comparison, with good notes to
point up the listening.
The Golden Age group is British, conducted
by its first soprano whose voice is one of those
incredibly high boy- soprano instruments that
one finds only in British lady singers. Indeed, this group sings nt a higher pitch level
than I would have imagined possible in this
day of big, operatic vocal production. An
extraordinary sound, almost vibrato -free. Only
complaint : as is often the case in British
singing, the Italian diction is something less
13
MONAURAL 4251)
BINAURAL 49só
Reviewing this (lise is a matter of description ; this choir is one of the best there is of
its type, and the only question is -do you like
this music?
The spirituals, in this form, are made into
fancy choral arrangements with humming,
solo voices, etc., effects not far from those of
the well known Fred Waring ensembles. The
performance is highly perfected, polished. balanced, the voices are superb as might be expected and the singing -given such fancy
stuff-is quite spontaneously emphatic. So,
if you like arranged spirituals, this is for you,
but definitely.
If you prefer "authentic" negro folk music,
in the si ut pier and less artful ways, then
look elsewhere. This is hardly rough -hewn
primitivism. Lend Belly probably wouldn't
even recognize the tunes.
Old Possum's Book of Practical Cats. (Six
poems by T. S. Eliot). Musical setting by
Alan Rawshorne; Robert Donat, speaker,
Philharmonia Orch., Rawshorne.
Angel 30002
This is the kind of title that snakes one sit
up, especially if one is a cat -lover. (Or maybe
cat -hater.) As one of the former. I sat
I'd love to on me a real practical cat.
Well!
There's a lot more than a passel
of eats here. First, a great, big, hi-fi overture,
n
up.
...
that'll titillate your monster speaker very
AUDIO
52
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AmericanRadioHistory.Com
MARCH, 1956
nicely, cats or no eats. Nicely dry, expressive
modern stuff. pleasant and appropriately unimportant for all its noise. with n faintly
19 2O's sound-but more of this in a moment.
Then, after n pause, starts Poem No. 1,
about naming cats, three names for each one
of 'rut. Rhymed stuff, this, and against it tI
say that advisedly) there is more music for
the big orchestra. The two interfere a bit
tonat has to read pretty loud to be heard. No
discreet fade -down background music here!
Indeed. the music is oddly independent, in the
background merely via distant -mike recording
rather than by any intrinsic "background!less". The following rive poems about casts
continue the same -and I will not give their
witty content away. But the nmsie .. .
It plays like a six -sided symphony while
rornat reads of cats and cats and cats. And,
at the end, it suddenly has occurred to ore that
this piece, with all its non -farting, nonbackground. accompanying music. has only one
other counterpart In the field. Thal, unexpectedly, is a piece all of thirty -odd years
old, right out of the Twenties. It, too, had
sing -song rhymes read against, rather than
errs- a snazzy, witty musical score. (That was
before radio backgrounds.) In that piece. too,
the speaker buds the going a bit tough against
the constant musical competition. and in it,
tan. the listener rather wishes, after awhile,
that he could hear each section apart. Verses
without all that musical list rant ion
music without the droning voice to gum it up!
The name? "Facade," by William Walton.
with text by Edith Sitwell. and you'll find
six different jolly LP versions of it in the
catalogue Four of them, note well, are withcut words.
By all means, if you like cats, try this practical little disc for size (10 ") on your cat -like
instincts. And. if you are enterprising, get
the companion London recording of "Facade,"
inn, with the raucous- twenties verse spoken
by Edith Sitwell herself and Peter Pears.
Landon LI. 1133.) It's really a better work,
rats or no cats.
-
-or
I Taught my Mother. Charlotte Rae;
John Strauss and his Baroque Bearcats.
Songs
Vanguard VRS 9004
Maybe somebody's sides will split over these
ditties. Mine are still in our piece. The allusion, in case your music appreciation is behind
time, is to "Songs my Mother Taught Me", a
singular song, if I remember rightly (Le., not
plural), by Dvorak, out of his Gypsy Songs,
and a lovely item, too, which you would
recognize in an instant if I bummed it to
p ou.
Anyway, Miss Rae's "silly. sinful, & satiric"
splitt ingly funny but they're
splittingly unmusical to my ear, as well. She's
songs may be
not even the kind of imp or pixie (ne the notes
suggest) that I'd like to bring home to meet
mother.
Try for yourself, if you like party entertainment records. I could be wrong-very
wrong.
Theory of Classical Greek Music.
Fritz A. Kuttner, J. Murray Barbour; Rob-
The
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EVERY NOTE of music from tile sonorous
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reproduced with stunning clarity by the
"Golden Treasure" Cartridge. Long -lasting G -E diamond styli* reduce wear on
record grooves to make records last longer,
sound better. General Electric is the choice
of audio experts. professional broadcasters,
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Only General Electric has the exclusive
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placcElent so easy. With Clip -In -Tip, anyone can replace a G -E stylus instantly.
Now it's easy to use good styli all the
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When buying a new cartridge, or replacing a worn -out stylus -be sure you insist on the genuine G -F. See your hi -li dealer
for a demonstration. General Electric Co.,
Special Products, TV Dept., Seaton R4436,
Electronics Park, Syracuse, Neu. Fork.
*G -E sapphirrr available at Auer cost.
ert Conant, harpsichord.
Musurgia Records (1A)
Don't be misled by that "harpsichord" list.
ing into expecting music on this record. There
is tone. excepting for a couple of very
ancient Greek hymns, played in their original
scales. They sound dreadfully out of tune
to our ears. The rest of the record le entirely
s«ailes and Intervals -"example 29" intoned
l v
a low -fl voice, followed by deliberately
spaced harpsichord notes of various degrees
cf oat- of- tunedness. This goes on for almost
a hour.
What is It? A highly concentrated musicoI,gical study, for the first time with actual
illustrations, of the tonal theories of the
;reek writers. It is doubtless a very important work and I know that music libraries
ill over the country will want the record and
its successors.
I am well aware that the old Greeks
wrought mathematical miracles in their exact
.ieterminntions of scales, tones, sound- vlbratIons. Modern theory of all sorts is really
AUDIO
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ELECTRIC
53
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Listening quality
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Consumer sheet:
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based on their work. I know, too, that the
problems of scale pitch that were solved
variously by these gentry are for the most
part eternal problems of music itself, that
still must be coped with in spite et our convenient (and out-of-tune) tempered scale.
But, alas, with the best will in the world
I find this material not only audibly unendurable, beyond a band or two, but also Just plain
boring. And I can tell you why, very reasonably. Perhaps my reason has a bit to do with
the difference-so often pointed out -between
musicians and musicologists. The trouble with
all of these subtly different sound illustrations
is that they aren't music. And so my musical
ear simply can't get hold of them in any
intelligible way.
Now I have a pretty good ear, by repute. I
am acutely aware of right and wrong pitch In
all music -and especially in choral and string
music that is often free of tempered pitch.
and in older music that cannot even be performed with tempered pitch. I've sung it,
have conducted it. But these non -musical
pitch sounds, here, just leave my ear confused. Either they all sound alike (all subtly
out of tune and unpleasant) or all unlike but
equally unpleasant.
The reason is this. Music Is dynamic. It is
sound in motion, through time. Musical pitch
means next to nothing unless it moves
a
part of a moving sound-pattern. Stop the
sound, isolate single tones and forget the
context-and they are no longer music nor
do they make much sense. Pitch to my ear,
to be musical, must move -always. And here
are dozens and dozens of exact pitches and
pitch relationships, virtually every one musically lifeless, completely static.
The simplest comparison I can think of
is that of a tape recorder. The mind and the
eye can analyze a stopped tape recording for
its sound constituency. But the ear cannot.
The very instant the tape stops it loses every
vestige of sound -sense. That's what I mean
by dynamic.
-is
New York Foundling Hospital Benefit
Concert. Solos, Mozart Choral Society,
Boys' Choir.
Impresario A-5137
This isn't for sale but if you want to help
foundlings you may have one for a $5 donation. Speaking of pitch .. , this one features
a more or less amateur concert (maybe allamateur, for all I know) in which the sense
of dynamic pitch -see above-is so excruciatingly twisted and warped that you'll
howl with horror or laugh with glee! Really
a quite amusing concert ; everybody is so
sincere and works so hard -and so out of
tune. It's just that amateur events Ilke this
don't often get on LP records and the sensation is, to say the least, odd.
Add this to your Mme. Jenkins records
(remember her ?) and do the foundlings a good
turn. Address: N. Y. Foundling Hosp., 175 E.
(18th St. New York 21, N. Y., Itt. Rev. Msgr.
J. Reilly.
Arlene Francis presents Music Appreciation for the Home.
Camden CAL 256
Good homebody Arlene Francis (she's seen
-
in almost every home) here gives two lengthy
and mellifluous lectures upon -guess what
the Unfinished Symphony and the Nutcracker
Suite, those old standbys of Great Music for
the Beginner. There are a few -not very many
-musical illustrations here and there, presumably (by the sound) from Camden reissues.
Oddly enough, Miss Francis' talks are quite
well done up and interesting in their background subject material, though there isn't
much room left for the music. (That might
prove too heavy for long listening.) I don't
know whether she wrote them herself, but I
can only say that her dulcetly sweet -toned
golden TV manner will make almost anybody
quite sure that she has a good ghoster. It
just sounds that way-overwhelmingly.
500
Fifth Ave., dept. A, New York 36
Fine audio -electronic apparatus over 30 years
Angel 3522C (3)
I tried some of this, then turned it over
to Scout #2 without comment. We agree.
"The whole Job is done lovingly and beautifully, and who's more beautiful than Schwarz kopf -but they're doing the wrong opera." She
and Nan Merriman "sound like the female
duets from 'Rosenkavaller'." Exactly.
Though Austrian, this is an Italian opera
all over. These serious, modern -day Austrians
simply do not get the brittle, gay, tongue wagging spirit of it. Not really very good.
Mozart: Die Entfuehrung aus dem Serial
(Abduction from the Seraglio), K. 384.
Soloists, RIAS Symphony and Chorus,
Fricsay.
Decca DX 133 (2)
This rip -roaring mock- Turkish opera farce
of Mozart's gets a "sweet" production, musically-, here, "quite delicious" -which is not
exactly my idea of its robustious qualities.
But Scout #2 goes on to say that the spoken
dialogue seems to be curtailed and he misses
it strongly-too much music, without proper
breaks and contrasts.
This is a very valid point. Mozart (as other
opera composers who nix music and dialogue)
calculated his pace and timing rather more
carefully than some people imagine who think
the dialogue is corny and dispensable. It isn't,
really, even when you can't understand it.
Necessary contrast.
The older London recording (ELLA -3)
which I found absolutely delightful, has three
records to this Job's two. I suspect a part of
the difference is in the removed dialogue,
though I can't check at the moment. And by
the way -this dialogue is awfully funny, In a
Katzenjammer kids sort of style. I'd gladly
pay the difference for it.
-6
Tchaikowsky: Symphony
( "Pathétique"). Philh. Symphony of London, Rod zinski.
Westminster WN 18048
I tried this first, then sent it on to Scout
#1 to see what would happen. He feels that
ltodzineki (ex -N. Y. Philharmonic) has long
been one of the finest Interpreters of the
work ; this version is generally like his older
recording made in New York, now on Entré,
though the first theme is slowed down, the
finale louder.
He thinks the third movement, in both, is
the finest concept of that music on records,
and I agree with him. I found the scherzo style music extraordinarily interesting here.
But the beginning of the work drags along
in the strangest way, oddly bottled up in itself ; there is a curious inability to get going,
to "let go," which is doubly curious in the
light of the emotional shambles that we so
often hear in these passages.
The recorded sound bothers me. It is "hi -fi",
of course, but in a rather special manner ;
the strings are very remote, the brass painfully near at hand, a very poor musical balance which we hope was not purposeful, for
hi -er fi. It's decidedly possible that the odd
musical effect of the opening pages -for
entirely the fault of the engineerstrings
ing department ; for it is when the brass
finally appears, triumphant, that this. recording really gets going.
-is
' v k: Concertino; Mladi. Phila. Woodwind Quintet, Rud. Firkusny, pf., Leon
Columbia ML 4995
Lester, bass ciar.
J
I tossed this one to Scout #1 because he Is
gone on JanAéek, who was a Czech composer
who lived a long life and did much intense
writing, quite modern in his old age, up to
his death in 1928.
"Incredibly fresh, daring ". ". . white -hot
intensity
.
stunningly
the mark He
Janá.'ek a mild
.
!
SCOUTS' ROUNDUP-
AUDAH COMPANY
monies Orch., Chorus, von Korajon.
ITEMS TO CHECK
Mozart: Cosi fan Tutte. Schwarzkopf, Mer riman, Panerai, Simoneau, et al. Philhar-
luxurious, folkish modalities
recorded ". I seem to have hit
loves it. I think you'll find
and "folkish" modern, quite
easy to take ; I wasn't that enthusiastic last
time I heard him, but then, I have a lot of
music on my mind. Scout #1 suggests a look see- listen to Westminster's more "biting"
Concertino, with the Baryilli group, while
you're at it.
AUDIO
54
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
NEW LITERATURE
Electro- Voice, Inc., Buchanan Mich., is
publishing a new "Guide to High -Fidelity
Loudspeaker Systems." It gives details
about integrated 2 -, 3 -, and 4 -way speaker
systems, and acoustically- designed furniture- styled enclosures to suit the individual budget and esthetic taste. Also included is information about Electro -Voice
do -it- yourself hi -fl enclosure kits. Of particular importance to music lovers is a
section which tells how to choose a
speaker system for fullest enjoyment of
hi -fl music reproduction. Your request for
a copy must include twenty -five cents
($.25) to cover handling and postage.
Specify that you want Catalog No. 117.
141
Terminal Radio Corp., S5 Cortlandt St.,
,New York 7, N. Y., offers a storehouse of
worthwhile information for the music
lover, hobbyist and professional audio engineer in its "1956 High Fidelity Guide,"
a 132 -page catalog of audio equipment.
The booklet illustrates and describes Terminal's complete selection of hi -fl phono
equipment, tunera, amplifiers, speakers,
cabinets and tape recorders. Also included
are microphones and public -address equipment. Consumer net prices are given for
all items. A free copy will be mailed on
written request.
M-2
Cabinart, 99 N. 11th St., Broklyn 11,
N. Y., in what is possibly the most com-
plete catalog of hi -fl furniture ever published, lists and illustrates the company's
entire 1956 line of equipment cabinets,
cabinet kits, speaker enclosures and enclosure kits, multi -unit speaker systems,
and furniture hardware and accessories
for the sound enthusiast. New products
for 1956 include thirteen cabinet and
speaker-enclosure kits, all in birch- or
white -pine veneered plywood. Ten of these
are matching and modular, and are designed as a wall- storage -cabinet series.
Cabinart offers the series as a build-ityourself home entertainment center. Cabinet measurements and construction plans
are shown throughout the 34 -page 2 -color
catalog. Copy will be mailed free on request.
X-3
LP312
l2w LOUDSPEAKER
NET. $49.50
University Loudspeaker, Inc., 80 S.
Kensico Ave., White Plains, N. Y., now has
available an informative and interesting
brochure describing the new do-it- yourself
kits for high -fidelity speaker enclosures
embracing University's exclusive Decor Coustic design. The booklet illustrates the
features of University's new "Kwikits,"
easy-to -put- together kits of cornerlesscorner enclosures which incorporate the
best features of horn loading, phase inversion, and direct radiation. Also included is
the utility model, in unfinished fir, of the
"Classic" deluxe 3 -way speaker system. A
copy of the brochure may be obtained
without charge by directing your request
to Dept. LAS at the address shown above.
X-4
Division, Radio Corporation of
America, Harrison, N. J., has just brought
nut a completely -revised edition of its "Interchangeability Directory of Industrial T3'pe Electron Tubes." This 16 -page booklet lists 2000 type designations of 26
different manufacturers arranged in alphabetical- numerical sequence and shows the
RCA direct replacement type or the RCA
similar type, whichever is available. Included in the listings are power tubes
rectifiers, phototubes, camera tubes, and
receiving-type tubes for industry and
communications. The directory is priced
at twenty cents ($0.20) per copy and may
be obtained from RCA tube distributors
or by writing to Commercial Engineering
Department in care of the address shown
Tube
above.
1t -g
Minnesota Mining and Manufacturing
Co., 900 Fauquier St., St. Paul 6, Minn. has
just published Bulletin No. 31 of the popu1 it "Sound Talk" series covering the effect
of coating thickness on the frequency response of magnetic tape. The three-page
laper, illustrated by four charts, is intended for broadcast engineers, electronics
specialists, and amateur technicians
interested in magnetic recording. In the tech!lest discussion, the effects of bias and
audio recording currents on high- and low frequency response on tapes with coatings
of various depths are outlined, with
particular reference to specific "Scotch" brand
tupes. The method of determining optimum conditions is given, and effects of
variance from these conditions are shown.
The bulletin is available on request from
the company.
M -6
AUDIO
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NEW PRODUCTS
Dyna High -Power Output Transformer.
Guaranteed to have a frequency response
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Tiny Speaker-Microphone. "Mini- Mike"
is a low -cost miniature dynamic speaker microphone which can be mounted in the
housing of dictating machines, portable
'
transceivers, and other electronic devices
requiring transmitting-receiving units. It
weighs only 1/3 ounces and is housed in
a case stade Of steel and plastic. Distensions are 1 x 1 x :4 ins. Available as an
accessory is a miniature transformer for
matching the Mini -Mike to grid circuits.
Sensitivity of the microphone with transformer is 52 db belote 1 volt dyne /sq. cm.
As a speaker the unit will deliver 120 db
with power input of 10 mw. Nominal impedance is 10 ohms. Further information
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available on request from Dyna Company,
5142 Master St., Philadelphia 31, Penn.
Knight Tuner-Amplifier. Aptly named
the Uni -Fi, this new low -cost combination
features unified design to achieve excellent hi -fl performance in compact form.
It has a full set of controls and combines
an FM -AM tuner, a magnetic preamp and
a 10-watt power amplifier on a single
chassis. Frequency response of the amplifier is 20 to 20,000 cps within ± 0.5 db.
FM tuner sensitivity is 8 microvolts for
30 db quieting. In addition to an input for
Capps Hot -Stylus 'Unit. Quality of disc
masters for microgroove records is greatly
improved over that obtained with coldstylus cutting when cutting is done with
a stylus heated by the new Capps hot stylus adapter unit, models of which are
available for all standard disc recorders
and cutting lathes. The unit consists of a
small lightweight stylus terminal block
`
`
a record player, an auxiliary input is
provided for use with a TV receiver or a
tape recorder. Included among the con-
trols are separate bass and treble adjustments, loudness control, and a three-position record compensator. The Uni -Fi is
housed in an attractive cork- grained metal
cabinet with brushed brass panel. Complete technical specifications will he supplied by Allied Radio Corporation, 100 N.
Western Ave., Chicago SO, Ill.
M -14
Bacon
Pneumatic- Damped
15 -Each
Speaker. A new principle in cone suspension which employs pneumatic damping to
afford long excursion and unusually low
resonant frequency, is incorporated in the
new "Ili-C" speaker recently introduced
by flacon Electric Co., Inc., 1261 Broadway, New York 1, N. Y. The unique suspension, for which patent has been applied, results in practically a "free- edge"
cone having great flexibility without encountering mechanical restraints. A special cellular plastic material is used between the cone edge and the supporting
M-9
Miratwin Magnetic Turnover Cartridge.
Consisting of two completely independent
and non -reacting movements mounted
back -to -back in a turnover mount, the new
Miratwin cartridge is the latest component in the extensive line of hi -fl gear
distributed in the U. S. by Audingersh
Corporation, 23 Park Place, New York 7,
N. Y. Frequency response of the Miratwin
is from 30 to 18,500 cps within + 2 db.
Recommended stylus pressure is
to 8
grams. Exceptionally high output of approximately 50 my at a stylus velocity of
which fastens to the cutting head of the
recorder, and a. control panel. The terminal
block features a unique quick- disconnect
feature for ease in changing styli. The
control panel Includes stylus -heat control,
pilot lamp, on -off switch, and a meter for
precise heater- current indication. The unit
operates from a standard 117 -volt 60 -cycle
n.e. line. Capps and Company, I ne.. 20
Addison Place, Valley Stream, N. Y. M-12
Eye -Saving Slide Rule. Design engineers
and college students will welcome this
new slide rule recently introduced by
Pickett & Eckel, Inc., 1109 S. Fremont
Ave., Alhambra, Calif. Scales are tinted in
green- yellow to coincide with the optimum
sight point of the spectrum, thus cutting
10 cm /sec. at 1000 cps results in remarkably high signal -to -noise ratio. External
magnetic pull has been eliminated to such
a degree that the difference in stylus
pressure with ferrous and non -ferrous
turntables is virtually unmeasureable.
Styli may be replaced instantly without
the use of tools. Hum factor is inconsequential. Available with either dual -sapphire or diamond and sapphire styli, the
Miratwin cartridge is designed for mounting in any standard tone arm. Catalog
sheet will be mailed upon request. M -10
eyestrain, blurring, and errors in reading
calibrations. Non-corrosive, non- rusting
metal frame construction eliminates warping, swelling, and binding. The rule is
available In 6- and 10-in. Trig, Log-Log
and standard models, or in models made
to special order. Free catalog on request.
M -13
basket. This material is composed of millions of microscopic cells which are randomly interconnected so that the degree
of damping due to stiffening of air within
the cells depends upon the amplitude of
cone motion. At large amplitudes, such as
at resonance and at low frequencies, the
damping action is maximum. Because the
damping mechanism is self- contained and
is not affected by enclosure characteristies, the Hi -C may be substituted for an
existing speaker in one's present cabinet
with corresponding improvement in audio
performance. The Hi -C line is available at
present in three 15 -in. models, a woofer, a
dual cone, and the triaxial Model 15 -HTX
which is illustrated.
M -15
AUDIO
56
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AmericanRadioHistory.Com
MARCH, 1956
HARVEY
Ike
JIo.use
MARANTZ
ai
Ada
Audio Equipment
New
40 WATT
POWER
AMPLIFIER
metered operational adjustment. Output transformer with low
leakage reactance and high flux -handling capability. New type -6CA7 output
tubes are more efficient and distortion -free. Variable damping from
separate 4, 8 and 16 ohm outputs. Oil input -filter capacitor, long-life
telephone -quality electrolytic condensers,
Built -in
$1890°
terminal -board construction.
411i
'
AUDIO
CONSOLETTE
Self -powered. 7 inputs. Input selector, loudness compensation, volume,
boss, cutoff filter, treble, turnover, rolloff, and power on -off controls. low
and high -impedance outputs. 3 switched AC power outlets. Response
±1 db, 20- 40,000 cps. 1% moximum intermodulation distortion at 15
volts output. 4 microvolts equivalent moximum
$16200
open -circuit noise at first phono grid.
AUDAX Hi-07
'Chromatic'
-
Magnetic Pickup CARTRIDGE and ARM
Widely admired for its natural sound, the Hi -07 features extremely high
lateral and vertical compliance, 20.15,000 cps frequency response, an
ingenious turnover arrangement with two individually replaceable styli in
a single head, and superb overall listening quality. It comes with one
diamond microgroove stylus and
ne a r- infinite- compliance "Chromatic"
$4770
one micro or standard -groove sapphire stylus.
Hi-07 Cartridge
Compass -pivoted tone arm
-
HF -12 (up to 12" disc)
HF -16 loo to 16" disc)
19.20
25.20
JansZen
Model
1
-30
PUSH -PULL
Electrostatic Speaker
NATIONAL
Criterion
$131500
HARVEY carries a complete line of pre- recorded
tapes, blank recording tape, tape accessories,
blank recording discs, and recording styli.
The New
RESEARCH
ACOUSTIC
AR -1
SPEAKER SYSTEM
Revolutionary acoustic suspension system provides o bass response hitherto
unobtoinoble. At the same time, this
is accomplished with o speaker cabinet only 14 "x11 s/e "x25
ARI with 12" woofer and 8" mid -and -high frequency unit
in finished cabinet
AR -1U some as above in unfinished cabinet
AR -1W woofer only in finished cabinet
AR -1WU woofer only in unfinished cabinet
New
$18500
5172.00
S145.00
$132.00
MICRO
Floating Drive
TURNTABLE
ssmbnn
_
Built to professional standards, the new MICRO turntable unit features a
unique and ingenious floating drive system which provides complete
acoustical and mechanical decoupling between motor, base and turntable
for flawlessly smooth and silent performance. The xclusive MICRO shift
hile the turntable is
makes possible instant selection of any of 3 speeds
operating, without damage to the drive mechanism.
$5950
MICRO 12, with 13" x 14" heavy -gouge steel base and MICROMATIC
74.50
Shift
119.50
MICRO 12H, some with hysteresis synchronous motor
ELECTRO -VOICE
Model 666
Super -Cardioid Dynamic
Microphone
ohms with internal provision for easily adjusting to
150 or 250 ohms Output is -57 db (Ref. 0 db
1
mw /10 dynes/cm2).
The Model 666 is ideal for TV, radio, recording and
other applications calling for high quality, and can be
used with boom, floor and table stands, and other
microphone mounts. Weighs only 11 ozs.
Complete with Stand Coupler and 20 -ft., 2- conductor
cable with Cannon UA -3 -11 connector.. ....._..$14700
=
with
independent tuning and level controls.
ception
feeding different programs to separate
Permits binaural
points or recording s one while listening to another. 'Mutomatic' FM tuning
nsitivity
eliminates noise and hiss. Other FM features include: 0.5 µV ssensitivity
4- section tuning capacitor
cathode follower
for 20 db quieting
output. Other AM features include: 10 µV sensitivity for 10 db signal -tocathode follower output.
image ratio better than 60 db
noise ratio
Has separate AM and FM section,
...
.
...
$189"
Everything worthwhile in high -fidelity equipment is IN
STOCK at Harvey's
our demonstration facilities are
second to none! Orders shipped same day received.
-
TIME PAYMENT PLAN AVAILABLE
TRADE -INS ACCEPTED
Prices are net, F.O.B. N.Y.C. - subject to change without notice.
,t,UDIO
One of the finest professional
tape recorders in the world. New
30s slant on top plate and revised
controls assure increased ease
and convenience of operation.
Available either with 15 and 71/2
ips tape speeds or with 71/2 and
33/4 ips. Frequency response to
15,000 cycles even at 71/2 ips. Over 60 db signal -to -noise
ratio at both 15 and 71/2 ips. Flutter and wow under 0.2%
at 15 ips and under 0.25% at 71/2 ips. Also available in
stereophonic models at increased cost.
Model 350 -C console recorder (illustrated)
1293.00
Model 350 -P portable recorder
1205.00
Model 350 -R rock -type recorder (less rack)
A wide. range, unidirectional microphone with a single moving element and featuring unusually high front to -bock discrimination. Frequency response is niform
front 50 to 13,000 cycles. The output impedance is 50
AM -FM TUNER
Complete with tubes
Tape Recorder
Complets
Reproduces the range from 500 cycles to bevo d the limit of audibility
with unprecedented smoothness. Eliminates all coloration and distortion of
the reproduced sound to a degree not possible wi h conventional electrodynamic "tweeters" of either the cone or the co mpression type. The
ultimate in faithful sound reproduction when used
$
_.. _._.. -.
with o woofer of comparable quality
184 00
...
AMPEX 350
Model 366
Made) 420
HARVEY
1123 AVENUE
....._
-- Table Stand -Mount
Boom Shock
._.__.__..____._
_._.._.__._...._._.
ESTABLISHED 1927
RADIO COMPANY, INC.
OF THE AMERICAS
(6th Ave. at 43rd St.) New York 36, N. Y.
MARCH, 1956
24.00
12.00
JU
2-1500
57
www.americanradiohistory.com
AmericanRadioHistory.Com
t
Fairchild Power Amplifier. Although it
is designed
.b lie r -5 wails cuntinuuusly, the new Model 275 amplifier is eon -
serv:uively rated ut 65 watts with inter modulation less than 0.5 per cent. Extremely compact, the unit measures only
121z, x 7
7 ins. Its weight, however, is 32
Ibs. even with the use of grain -oriented
laminations in the massive output transformer. The 275 will not oscillate nor will
it change over -all gain at any setting of
the du loping control, which is adjustable
from 0.1 to 10. Taps are provided on the
primary of the power transformer I. permit full power output at any line vollug.
Prout 105 to 125. Also included are r, -adil
aooessible adjustments for dye:unie boÌance of the 6551) output tubes, bias :nl
just ment, d.e. plate -current bal:nlcc, :soi
master gain control. loiter sien:ll r..luir..I
for full rated output is O.S volt rms. Out-
put impedances are 4, S, and 111 ohms.
Styled by Ilay mond Loewy- Associates, the
275 matches other }'airehild high -fidelity
equipment. Fairchild P,ecording Equipment Company, 54th St. at 7111 Ave..
\Vhitestone, N. Y.
5 -18
1
Stentorian Extended -Range 12 -Inch
Speaker. Utilizing a cambric ruile as in
other Stentorian speakers, the design of
Tandberg Two -Speed Tape Recorder. lip
to four hours of program material can be
recorded on a standard 7 -in. 1200 -ft. reel
of tape with the new Tandberg Model 2
tape recorder recently introduced into the
V. S. by peeves Equipment Company, 10
1`. 52nd St., New York City, N. Y. Operating at speeds of 1% and 3aß Buis, the unit
has frequency response curves within ±2
db from On to 4000 ens and from 60 to 7500
fps fur the Irr% and high speed, respecIiv.ly. \Vow is below 1..2 per cent. Noise
level is down 50 db. Start, stop, forward,
and rewind are selected by the proper
positioning r.f a single ''gear shift" knob.
Rf,ording lock guards against accidental
erasure. Speed selection is Afforded by a
Iewr which may be adjusted while the recorder is operating when desired. The
'l':rndòerg 2 may also be used as a public address system using its own built -in
speaker, or an external speaker by means
the new Model 11F -1214 also incorporates
six stabilizing discs of long -staple fibre
which :u,c impregnated into the front of
the eone to improve mid -register response,
particularly in the 1000 -3000 cps range.
Bass resonance is 39 cps and over-all frequency response is 25 to 14,000 cps. Power
rating is 15 watts. Complete information
will be supplied on request by Beam In-
struments Corp.,
York
1,
N. Y.
350
Fifth Ave., New
M-17
of an output jack. The Model 2 -1, is identical with the standard Model 2 except that
it Contains relays for electrically- operated
remote control which is afforded by a
plug -in foot pedal. Complete specifications
are available on request.
M-18
symphony in sound
,titepherry
is tlhutys
note.nrthv then selecting
the finest in superlative speaker systems.
Designed. constructed, and tested by
the pioneer sound engineers in high
fidelity equipment, the name Stephens
stands for true fidelity with music listeners
the u.irld over. Each pictured note represents
'quality speakers and components
that will insure the listener a true symphony
in sound. Consult your Stephens dealer
as to a recnnuucnded Tru -Sonic speaker system
for your particular needs.
STEPHENS
MANUFACTURING
CORPORATION
8538 WARNER DRIVE / CULVER CITY. CALIF.
CABLE ADDRESS "MORHANEX" EXPORT ADDRESS: 458 BROADWAY. NEW YORK 13.
AUDIO
58
www.americanradiohistory.com
AmericanRadioHistory.Com
N
Y
MARCH. 1956
DYNAKIT
Mark
11
50 WATT POWER
AMPLIFIER KIT
Electra-Voice 100 -Watt Professional
Amplifier. Intended primarily for high fidelity wired -music and public -address
systems, the new Electro -Voice Model
A100 rack -mounting power amplifier offers
advanced features and performance characteristics at a low cost which makes possible new economy in commercial installations. Frequency response is 20 to 50,000
cps within ± 0.5 db and total harmonic
distortion is under 0.5 per cent at rated
output. Damping factor is adjustable from
OA to 10 to permit perfect coupling between the amplifier and the speaker system. Maximum power available is independent of the damping factor, remaining
constant at all settings of the control.
Additional controls include gain, balance,
and power on-off. Complement of eight
tubes includes four 6550's. Input of 1.25
volt rms is required for full output. Output impedances include 4, 8, and 16 ohms
unbalanced, 70 volts balanced, with 600
ohms balanced available in chassis. The
theme
cì4e
,
.,
"i
new
cosq
wciqS
BEST IN EVERY WAY
AlOe e, u,., is of two sections, each of
FINEST QUALITY
New circuit designed by David Hafler us-
ing the Dvnaco A-430 output transformer, sets new performance standards
both on the test bench and in listening.
,/
BEST SOUNDING
Smooth translucent highs and clean unmuddied bass characterize the Dynakit's
sound. Listening superiority is due to
highly stable circuit with outstanding
transient response and distortion reduced
to vanishing point.
which occupies seven Inches of rack space.
For full information write to ElectroVoice, Inc. Buchanan, Mich., requesting
M -19
Specification Sheet No. 53290.
several of Pilot's hi -fl components
In
a
RC -54
Record Changer
HIGHEST POWER
50 watts at less than 1% IM for
ease. 100 watts peak. Frequency
±.5 db 6 cps to 60 kc. Full power
20 cps to 20 kc within 1 db of
to add a
Pilot High-Fidelity Console Emsemble.
The new I'ilot Model PT -1040 is on AMFM radio -phonograph which combines
listening
response
to your
available
50 watts
without exceeding 1% harmonic distortion
over this range.
HIGH FIDELITY
SYSTEM
EASIEST TO ASSEMBLE
Write for details
Uses pre -assembled printed circuit board
and simple physical arrangement. Only 9"
x 9" x 6-5/8" high without sacrifice of performance, and can be assembled in 3
hours.
GREATEST VALUE
$69.75 complete with all top quality components, included pre -wired printed circuit
board, pre -punched chassis, protective
cover, and detailed assembly instructions.
Cmnplete specifications and circuitry on this new
ars .liher kit are available. See your Audio job be, or Electronic Parts Dealer, or write direct.
DYNA COMPANY
Dept.
A 5142 Master
St., Philo. 31,
CIRCLE 59A
AUDIO
Pa.
- today
DC-1
11
s
ROCKBAR CORPORATION
smartly- styled contemporary console cabinet. Included are the Model AF-825 FMAM tuner, a new basic Williamson -type
14 -watt amplifier, and an exclusive Pilot
3 -way 4- speaker system which comprises
a woofer, a mid -range speaker in a separate vented enclosure, and two tweeters.
The record changer is the Garrard Model
RC -80 equipped with a General Electric
cartridge with diamond and sapphire styli.
Frequency range of the PT -1040 is 50 to
16,000 cps. Controls include a 5- position
equalizer, a 6- position function selector,
and separate adjustments for treble and
bass. Two built -in antennas are incorporated-a ferrite loop stick for AM and
a folded dipole for FM. Dimensions are
28% "hx35% "wx 16%"d. Concealed casters permit easy moving. Pilot Radio
Corporation, 37-06 36th St., Long
City 1, N. Y.
I, land
,nd
M -20
MARCH, 1956
215 East 37th St., New York 16, N.Y.
Please send me complete information about the "two new pre-wired
and pre- mounted Collaro RC -54 units
designed for ready use.
Nome
Address
City
Zone
State
CIRCLE 59B
59
www.americanradiohistory.com
AmericanRadioHistory.Com
Razdand
"GOLDEN
SERA'
HIGH FIDELITY
0A9 gee* Leal
U
tdward Gatnall Canby
NEW SPEED
FM -AM HI -FI TUNER
Here is quality FM (response ± 0.5 db,
20 to 20,000 cps) and improved AM,
both most perfectly realized for finest
reception in a unit only 4" high
a
very reasonable price. Outstanding fea-
-at
-3
tures: Sensitivity, FM
microvolts for
20 db of quieting; AM -5 microvolts
for 1.5 volts output; separate RF stage
on FM and AM; discriminator with
dual limiters; cathode follower with 2
outputs; AFC; flywheel tuning, FM
di -pole antenna, etc.
NEW! HI -FI SOUND FOR TV!
Now, make your TV sound "coma
olive". Just plug the new RAULAND
TV55 Tuner into the unit above and
enjoy TV sound through your hi -fi system.
Exclusive with
hear it soon.
RAULAND.
See
it-
20 -WATT HI -FI AMPLIFIER
Designed for those who appreciate the
finest in Hi -Fi reproduction-the very
best for less. Features: Full 20 watts
output; response, ± 0.5 db, 20 to
40,000 cps; 6 response curves (compensation for all record types); 5 inputs for
complete hi -fi versatility; separate bass,
treble controls; contour and volume
controls; variable damping control;
rumble filter, plus many other deluxe
features. In compact cabinet, 4" high.
HANDSOME "SPACE- SAVER" DESIGN
RAULAND matching "Space- Saver"
units are decorator -styled in smart charcoal black with marbleized gold finish,
control panels in soft brushed brass. No
cabinets required
beautifully any here. (Extension shafts available for
behind -panel mount.)
-fit
Hear these
RAULAND Hi -Fi
units at your
dealer's, or write
for full details
RAULAND -BORO CORPORATION
3515 W. Addison St., Dept. C. Chicago 18, III.
This time it looks as if 16% rpm were
going to stick.
No use trotting out all the old laments
about how we already have too many speeds
and another one is unthinkable. We've
been through that before. If 16 rpm has inherent commercial advantages, it'll be sold
and that is that.
Columbia was as clever in this as it was
in bringing out LP. "16" has been in the
wind for a number of years, but until now
it hasn 't, so to speak, found anything to
ride on. Though some optimists put out
four -speed changers awhile back, the 16
records that finally then appeared were
something less than a squeak, a new type
of talking book. Interesting but hardly
earth-shaking, and the quality really wasn't
very good on them, with standard microgroove, on the batch I once tried (with an
adapter of the "microverter" type, put
on a 33
table).
The clever aspect of the present super
small groove 16 is the hiway gambit. Who'd
a 'thunk it! Somebody with a pretty sharp
mind, and it might just possibly have been
Goldmark of CBS, who has his fingers in
such things. Whoever it was, the idea was
a honey, I guess. That is, it was something
that would work out practically.
16 rpm in the homey That, my friends, is
the biggest question. I don't give two mills
if all the cars in the U. S. come with hiway
hifi built -in, for 1957. Most cars already
have radios and the hifi and record businesses have survived nicely, even though
(natch) car radios are "hifi" too, nowadays. Perhaps 16 rpm will succeed in autos,
perhaps not. I don't care.
But how about the homes Will we have
another speed there?
I fear that we may, because of some
fairly irresistible pressures. I haven't even
heard the 16's yet, but I know a bit about
them, and I opine roughly as follows.
Small records that play fabulously long.
Much lowered cost per minute of music.
Quality that is remarkably good-remarkably, that is, in view of the size and speed.
Not really hifi in the most dignified sense;
at best a sort of jiggered up hifi, a reasonably flat output achieved by a rather large
amount of backstage tinkering with special
equalizations and what -not. Nevertheless
quality that could easily come up to the
sort of pioneer "hifi" that was so successful in Columbia's well known 360 table
phonograph. That, too, was rigged and
jiggered, not in the records but in the reproduction; but it did represent a legitimate improvement over the then- standard
"home phonograph" sound, and Mr. &
Mrs. Public recognized this quickly enough.
There you have the basic facts. The most
important, I'm sure, is the potentially lowered cost of music on 16. That's the factor
-
60
that always upsets ye olde apple carte. I
don't at this point know the present prices,
nor the potential mass- production prices in
the hypothetical future
very different
matter. (Most new gadgets, like the ball
point pen, start expensive, then work down-
-a
wards as production grows.) But my suspicions are that if this 16 -rpm record really
caught on-in some form or another, in
some field or another the price would drop
out the bottom of the record market, and
no quibblings about hifi either. Who quibbles, really, about that in the mass market?
The function of hifi in the mass market is
to give the admen something to talk about
and the buyers something to dream about.
Nobody, neither the one nor the other,
ever gets to the fi itself.
But what field, what form? Well, there
are already some new four -speed changers
announced. Somebody thinks that the big,
bulky, clumsy home changer is going to
play these dainty little miniatures. Maybe
at first -but I don't see that lasting per manently, the 45 notwithstanding. It would
seem to me that the miniature- component
revolution, now long overdue in the record
playing field, might really and at last be
set off by 16-for the record was the last
necessarily "big" object left in the player
mechanism. The turntable and its big record have determined the system 's size.
Remember, we've been using miniature
cartridges in absurdly big shells for
years, the shells still left over from the
pre-war period. We've been using big arms
too, not only long but generally bulky, also
pre -war style. The tiny 45 arm, in the original player, didn't catch. But that, of
course, was with the "large" micro grooves. With 16 -rpm grooves, far smaller,
the big arm is going to be left in a pretty
unstable spot. Just take a look at the hiway
hifi arm, counterbalanced (like the Pickering arm) so it won't joggle. Ingenious!
(Who was it used to argue with me that
the LP record was no good for dancing
-the needle would skip; only the big 78
groove would dot Fiddlesticks! Given the
right arm, the LP system is far less liable
to external jarrings than the older type of
heavyweight 78 arrangement. Elementary,
my friends, and the new 16 -rpm proves it.
You could even dance in an express train
with it
you could stand up on the
curves.)
Miniaturization of the record, the turntable and the arm assembly will complete
the very practical revolution that has been
in suspense ever since the small groove and
the small cartridge came in together. It
could be a vital part of the 16 -rpm future.
But -biggest question of all -what will
be on the new little records? That is the
crux of the matter, in a way, for until the
shrewd promoters figure out how to
"angle" the 16, how to fill it up for beet
effect, they will get nowhere. Anything-
-if
AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
.-corm -. faF -Jop Products CO.
from singing commercials to Bach cantatas-is possible.
I have at this point only one fundamental
thought. The new discs are too tong. Think
that one over carefully before you jump on
the 16 bandwagon.
Three Beethoven symphonies for a quarter! Well, maybe not that cheap, but who
wants three Beethoven symphonies on one
record( Three or four records, low- priced,
and you've run right through Beethoven.
And suppose you want the second movement
of Symphony #5, somewhere in the submicroscopic middle of those silky, invisible
supermicrogrooves. No bands here! Not of
the sort you can see and feel easily.
Suppose it's Mozart. Nothing less than
a gigantic potpourri of this and that and
the other item would do, to fill up these
giant timed discs. Whole programs at a
gulp, and not chosen by you, to your taste,
either.
jazz? A whole jukebox full on one record, and you can't push one of those nice
red plastic buttons and get the piece you
want, either. Backgrounds Ah, there's the
real use for a lot of 16 rpms. Music for
Everything, from cooking eggs to winding
up the cat and putting out the alarm. Music
all day from a handful of tiny discs.
So, to be serious, I think that the content,
again, is the big problem on 16. Maybe you
can run a very narrow band, shortplay,
around the outside of the disc, but in the
past this has never failed to make trouble.
Logically or no, people always feel gypped
when the space on the record isn't filled
out. You can always spread the grooves,
and that remedy, no doubt, will be widespread on 16, thereby undoing systematically a good part of the work that was done
in cramming in so many grooves in such
a small space. But with so much -so very
much -space to cover, in terms of time,
even this remedy, groove-spreading, isn't
going to help much.
What happens if records are too cheap?
What happens if you can get too much
music for your money, on too little space?
More than you want and, worse, a lot that
maybe you don't want at alle That's to be
seen, if and when 16 -rpm invades the home.
IDEAS IN THE MAIL BAG
Week in and week out, I set aside a
trickle of letters into a special file
marked IDEAS. These are letters I've
found particularly interesting or informative, or letters which have set off some
chain reaction in me that is likely to
spill over into print sooner or later. Generally I tend to answer these and then
put them out of mind, or glance at them
later just to remind myself of the subject
matter. My hard -working subconscious gets
around eventually to the points at issue
and heaves the stuff back at me again when
the time is ripe. But sometimes it's good
to quote verbatim from a few of these
epistles, as I've done in the past. This
month I'm pulling out a few on which
to comment at some length, with thanks
to their respective authors.
1600 West 25th St.
An old friend, five years in Tokyo as an
Al' correspondent, is an ardent hi-fier of
long standing and has recently written me
a bill of particulars on the subject, date-
line Tokyo. Just to emphasize his points,
the other day, he flew in himself (for a
promotion, I think) and said the whole
thing all over again in person. Told me I'd
better quick put something in my column
AUDIO
HIGH - FIDELITY
Baron Electric Company, Inc.
1261 Broadway
1, New York
New York
SKEPTICS
Gentlemen:
!
This is a report on a number of tests we have run on the Racon 15 -HTX, 15" tri-azial
Loudspeaker and here is what we found:
We started off playing records that went down to 16 cps and went up to 20,000 cps,
using a Rondine B-12 -H turntable, an Electrosonic professional cartridge and the
Interelectronic Model Coronation 400 40 watt amplifier. This amplifier is the one
I spoke to you about. It has a frequency response range from 16-35,000 CPS
We found that the speaker responded very nicely. So then we took a Cook
Frequency record to find out if we had any peaks and found that we didn't
have any. We were overjoyed.
We then used an Audio Oscillator and it turned out to be very
Write for Free
better than any speaker we've tried. This included a 15
good
inch
Literature
,
with a cross -over network and tweeter and
-
The final test we made was with a vacuum tube voltmeter and an Oscilloscope.
We found that the Racon 15 -HTX speaker will
respond without any distortion from 18 to 22,00(
cps, which in my estimation indicates you
can't purchase a better speaker on the
market today.
You have my permission to use any
part of this letter in any of your
SPECIFICATIONS
advertisements.
POWER: 25 Watts
Yours truly,
IMP: 8 ohms
Chester Drozdz
RES: FREQ. 24 cps.
FORM -A -TOP
FLUX: 14.500 posa
PRODUCTS
RESPONSE: 20-20.000 ept.
CO.
CROSSOVER: 2000 and 5000 cps.
*Speakers ranging in price
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WEIGHT: 23 lbs.
PRICE: $109.50 audiophile
Q!lw
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RECORDS PIANO MUSIC
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The quality of performance contradicts the entire concept that slow
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Two speed
dual track
Magic Eye level
Signal to Noise ratio: greater than 50 db
and Wow less than .2 °'° at 1?é Inchu /see.
low level output to amplifier system.
indicator
Radio or Phono input
Monitor inapt for head phone
OTHER FEATURES INCLUDE:
a three position switch for playback thn Its
Radio or phono input can be mixed with microphone input
as public address
. use
playback amplifier has 5 watts audio mane
own speaker or hi -t speaker, or both
folly
25 feet mike cable
amplifier system
crystal mike with response of 50 to 10,000 cycles flat
4 hours playing time with 1200 ft.
shielded heads
interlocked record switch prevents unwanted erasure
reel of tape
tape retracts from heads in last forward
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MARCH, 1956
61
www.americanradiohistory.com
AmericanRadioHistory.Com
-
about Japaness hi -fi and suggested maybe
I'd like to call it "WATCH JAPAN."
Well, I'll pass on the basic information
that Japan is moving in on hi -fi with the
-e-'''''r
usual enterprise of that country's business
and the usual extremely low production
costs combined with remarkably high quality and plenty of designing ingenuity
and this gent expects there'll be some
heavy invasion of the U. S. by Japanese
hi -fi products before very long.
The Japanese, as you must know, are
very skillful at adaptation. Let 's not call
it imitation. That word implies a slavish,
non -intelligent horning -in on other people's
ideas and products. It also implies a necessary inferiority in the imitation, for imitations are by definition unimaginative. The
original product is the one which results
from intelligent brain work. The imitation
is bound to suffer.
But adaptation -yes. That implies an intelligent, calculated borrowing of basic
ideas, concepts, even models, for a similar
but not always identical product in terms
of local industrial potentials. It may be as
good as the original and often is an improvement. We've seen what the Japanese
can do with such precision products as
cameras and field glasses which they
adapted mostly from German originals.
(I have a marvelous binocular, sent over by
this same correspondent some years ago.)
Now it's going to be hi -fi, and though we
may not like the borrowing of ideas, we're
going to have to compete with it and
admire it. Or tangle ourselves in a dismal
welter of lawsuits and Congressional bills
of exclusion.
-
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"As you have probably seen
hi -fi has
come to Japan," writes my friend, "and
it is pretty good, too. A smart business man
would start getting import rights. They
are making some fine stuff now."
B. B. BUTLER MFG. CO., INC.
3151 Randolph Street, Bellwood,
Illinois
CIRCLE 62
;L17.
IF you remember
Wurlitzer-
fondly the glorious sound of the Mighty
-
still thrill at recordings of these famous instruments
IF you
IF you're not so young you
be glad to know that
never heard one
You'll
-
THE THEATRE ORGAN IS COMING BACK!
Keep abreast of its return to a place of high esteem by reading
J
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1
Write name and address
j,4
in margin below and return with your check or
money order to
RADIO MAGAZINES, INC.,
P. 0. Box 629, Mineola, N. Y.
For instance, the Japanese have already
launched a small speaker in the U. S. which
is said to have outstanding characteristics.
If I am right, it sells, ready -mounted in
a special reflex enclosure, for around $22
here, which is unbelievably cheap in view
of the U. S. competition it runs into. The
speaker is said to compare very well with
such standbys of the present market as
the British Wharfedale itself, with cloth
surround, and the American Permoflux.
But here's the joker. I gather that this
sort of speaker sells in Tokyo for the
equivalent of a $5 bill, more or less, and
this to the general public. Take that.
"Japanese amplifiers are good but no
bargain in the states," says my friend,
"pickups are not bad either, but still no
better than GE. Speakers are coming along,
too. with some intriguing things like
leather -suspended 20" woofers.... Heavy
turntables are excellent with cast bronze
platters and big G.I.-type motor and low
rumble." The fellow is enthusiastic about
this development, especially the bronze
table which is heavy and a good flywheel.
"But
But the best buys are arms. They make
some real honeys here. The various Gray
models are imitated down to the last screwhead and so is the Pickering. . . There
are some good ones of a sort of combination Clarkstan- Livingston design that are
also excellent. But the best one I've seen
vet is a scaled -down 12 -inch adaptation
Gray 108B."
Remember, I'm merely quoting ideas,
as a sample of what maybe a lot of
U. S. hi -fi manufacturers are likely to
be in for in the days to come. (This fellow
brought one of these arms over to me and
so maybe I'll have more to say about it
later on a personal try basis.) I suspect
Gray knows all about this arm already and
I can only suggest that there are two sep-
AUDIO
62
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
arate problems which are major ones in
all such cases.
(1) Does the Japanese product really
compare favorably to our own -are they
up to us, or even ahead of ust Are we
keeping our designing and ideas up to
theirs
(2) What can we do about the drastic
production-cost difference, that favors the
Japanese product even when import costs
are added
As to the first of these points, I suggest
that righteous indignation on the part of
our manufacturers will not get them very
far, however justified. Keep in mind, as
I say, that the Japanese genius is for inspired adaptation. Call it ruthless, lawless,
unprincipled, if you will, but recognize its
intelligence and skill. It would be folly to
do otherwise. Legal measures no doubt can
and will be taken in some cases, and with
every reason. But just don 't under -rate
the Japanese ability.
As to the second, the unfavorable economic ratio that gives the Japanese a
whopping basic advantage, I can similarly
limit myself to the same sort of suggestion.
Don 't let the low Japanese production
costs blind us to good work on their part
and when. Good work is good work,
at any price.
The ideal situation, of course, would be
a government protection that would put
Japanese goods on our markets at competitive prices, design for design. But
who's to determine what is fairly competitive and what is sheer exclusion of foreign
trader And who's to say what effect this
might have on our diplomatic situation in
that ultra -ultra-touchy Eastern areas
Truly, it's one world with a vengeance,
these days. Not even a pickup arm can be
imported without rocking the international
boat.
-if
I'll add a few more items on the present
picture in Japan. "Japanese AM radio
continues first rate -flat to 10,000 cps,
which makes listening very easy.... Japanese studio engineers, using Alters and
Telefunkens, can show our radio people a
thing or two. The Japanese AM broadcast
of Gieseking and Szigeti here was the finest
radio sound I've heard, FM or no. I use
a germanium diode tuner (the J. W. Miller
circuit) and it is terrific. Cost $12."
"The whole country is music- mad-all
kinds of music, right up to mambo. University kids sell their blood literally (its
for transfusions) to buy concert tickets
when big -time foreign artists come here.
The US could do well to send more people
like the Symphony of the Air here. It
would help balance the necessary but unpleasant defense installations.
"I'm still making up hi -fi sets
some
22 by now. For the upper stratum I use
Japanese turntables and arms, a much
superior setup.... I've more or less stabilized on the (XXXX) amplifier, the
(XXXX) for folks who want changers,
and (XXXX) cartridges...." (I am censoring the brand names since this is no
...
export competition department). But I
would like to note that this gent now has
a habit of making up special speaker cabinets that take advantage of the incredible
price bargains open to Americans. Twelve ply Phillipine mahogany is his standard
building material!
His own over-size Klipsch "short horn"
(in consultation with Klipsch himself, I
gather, and so with permission) is framed
in gorgeous wood with genuine six -coat
Japanese lacquer, hand- applied over many
weeks. Cost about as much as a good coat of
wax in the U. S. The local cabinetmakers
do a fantastic job of carefully solid work-
AUDIO
manship on these boxes, following my
friend's designs though often they don't
know what they're building. Tolerances,
needless to say, may be made far more
exacting than for mass- production woodwork, yet the cost is just plain negligible.
And that brings up a final and rather
important point. I've had a number of letters recently, both from Japan and from
Europe, asking for specifications on various of the special speaker enclosures now
available -RJ, Karlson, Klipsch, etc. -so
that the writers could have special models
built by local cabinet makers. Some had
already gone ahead-and built up quite
sizeable businesses among Americans and
others interested.
Now most of these operations are at
cost, non -profit, and strictly hobby stuff,
on a relatively small scale. Nevertheless,
I have in every case answered these letters
seriously, suggesting that these people
were, knowingly or not, infringing on somebody else's rights, unless they had express
permission. Copying a patented design.
My Japanese friend, for example, has
been putting together some very nice RJ
cabinets. Twelve -ply Philippine Mahogany,
with bracing and screw-work of a sort
quite impossible in any commercial U. S.
model. He even worked out a corner triangle RJ, being an ingenious laddie himself, and this one is a lacquered job, at
that. How did he do its Simply, and quite
honestly, by taking the measurements from
a commercial RJ cabinet, and you may be
sure plenty of other people have done the
same, in all parts of the world and at home.
Licensing of such an operation is not
really practical. The return would be too
slight even if there were enough "business." There aren't published plans available either for most of these special enclosures for a similar reason; not worth
the small business. As I understand it, my
friend, who is an honest man, did apply
to the U. S. promoters and offered payment, but got only a negative reply for
his efforts.
And yet, just the same, I feel strongly
that as a matter of ethics none of us should
build a patented device, speaker enclosure
or what -have -you, without at least doing
our best to extend the courtesy of recognition to the people who did the work in
the first place and who own the idea.
I've suggested to my friend-and this
will put him fairly on his honor -that
much better than a payment of petty cash
would be a token of appreciation to the
inventor, out of politeness. A gift. My
suggestion was simple in his case -an RJ
cabinet. If he takes my advice, he'll ship
to R or to J, one of these days, the most
luxurious RJ cabinet either inventor could
dream of, 12 -ply mahogany and lacquered
to a fare -thee -well.
I'm sure any inventor would feel happily
recompensed by such an offering -worth
far more in the U. S. than it will cost in
Japan. And I suggest that all those who
are at present "borrowing" patented designs, including the group that wrote me
from Germany (special model inexpensively turned out by a local German cabinetmaker, for peanuts), consult their best
consciences as to what sort of a gift might
best express their appreciation of an inventor's work well done-for them. It's
only fair.
Speaking of "borrowing" (I'll get this
in under the Japan heading, while I'm
talking) there have been numerous deliberate commercial steals of equipment recently
in our very own sweet country, and not for
fun either. ET was the victim awhile back,
with models "borrowed" straight down
MARCH, 1956
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63
www.americanradiohistory.com
AmericanRadioHistory.Com
PRESS COMMENT
"Atlantic
(John M. Conty)
"The AR-1'07 woofer gives the cleanest
bass response I ever have heard."
AUDIO
(Eduard Tatna)) Canby)
the line, since suppressed, or modified beyond the immediate reach of the law. But
the crassest example I know of recently
made use of this column to promote a
"steal." The speaker cabinet in question
was advertised as the "CR -15 compressed
air acoustical suspenion speaker system"
in one ad and "Villchur-type" was added
in another, though it was in no way authorized or licensed by the inventor, Mr. Villchur, who sent me the ads himself. But the
"borrowers" went further than this, which
was at least straightforward if unethical.
. Read Canby's review of the system in
the latest issue of AUDIO and drive out to
Pomona to hear it, was the blithe suggestion.
That was not quite straightforward. For,
you see, I wrote my article about the Villchur AR -1, acoustical suspension speaker
system, the original. I have not heard the
CR -15 and do not intend to hear it, or any
other unauthorized version of the basic
invention.
.. the highs impressed me immediately
as very lovely, smooth, unprepossessing, musical (for music) and unusually natural. No
super-hi -fi screech and scratch ... As to the
lows ... I was no end impressed, from the
first time I ran my finger over a pickup stylus
and got that hearty, wall- shaking thump that
betokens real bottom bass to the time when
had played records and tapes on the speaker
for some months on end."
I
TNr.
Q//011
(B. H. Haggin)
.achieves the seemingly impossible; a
real and clearly defined bass in a cabinet only
14 by 11
by 25 inches in size."
RA111N
1:I.I:I:Y1tONIC8
(J. M. Krech)
"... reproduced the full range of bass,
even the pedal tones of the organ, cleanly
and spectacularly ... shook the concrete reenforced floors of the Hotel New Yorker..."
f
7%IC&Rdatia, Rellew
(R. S. Lanier)
"...goes down into the low, low bass with
exemplary smoothness and low distortion. It
is startling to hear the fundamentals of low
organ notes come out, pure and undefiled,
from a box that is two feet long and about
a foot high."
1111k 3idelitg
(Roy Allison)
.. a woofer that works exceptionally
well because of its small size, not in spite
of it
I have heard clean extended bass
...
like this only from enclosures that were at
least six or seven times its size."
THE AUDIO LEAGUE REPORT
(Oct., 'SS) Pleasantville, N. Y.
"Speaker systems that will develop much
less than 30% distortion at 30 cycles are
few and far between. Our standard reference
speaker system,' the best we've ever seen,
has about 5% distortion at 30 cycles."
Tire
AR -1W
The AR-1 "speaker system, in mahogany
or birch, is $185. Suggested driving power,
at least 30 watts. Literature on request from
Dept. A.
ACOUSTIC RESEARCH, INC.
23 Mt. Auburn St., Cambridge 38, Mass.
Circle 64A
ABOUT MUSIC
(from page 8)
theory-Messiah was composed in twenty four days.
Ignorance, poor performances, and lack
of faith in Handel's dramatic abilities
have conspired against these scores for
many years. Handel's biographers skip
over huge areas of his most important creative periods (all the standard books mention only en passant such a powerful opera,
for example, as Sosarme) ; when an unusual
score is performed it is generally assigned
not to the top singers of the day (as it was
done in Handel's time), but to artists who
have little sympathy and less talent for
Handelian style; and finally, one too often
forgets that an original musical mind can
overcome and even put to its service the
most stilted and conventional artistic formulas.
The LP era has seen steps taken to fill
the gap, but with generally disappointing
results. The few adequate performances in
the catalogue are still of the "until a better version comes along" variety. 1956,
however, promises to be a good year for
Handelians. In January, Sir Thomas
Beecham signed a contract with Angel
Records. To inaugurate his new affiliation,
he will direct the first complete recording
of the oratorio Solomon with soloists,
chorus and the Royal Philharmonie Orchestra. Two major Handel works were released
this year by London ffrr on the L 'OiseauLyre label: Semele (OL 50098/100) and
Sosarme (OL 50091/3). Technically, these
new recordings are head and shoulders
above comparable works already in the
catalogue -and that includes the L'OiseauLyre catalogue as well. The French clothes closet acoustics that mars older O -L releases
is replaced here with the delightful resonance and clarity one associates with the
best London products. The soloists are
mostly competent and at times superlative,
e.g., Alfred Deller's "instrumental" approach to his part, and Jennifer Vyvyan 's
easeful handling of both the lyric and
coloratura aspects of her role in Semele.
Conductor Anthony Lewis does not whip
up too much excitement but the New Symphony Orchestra (in Semele) and the Saint
Cecilia Orchestra (in Sosarme) play well
in spite of him. Also, the Italian pronunciation by this all- British cast is a bit on the
self- conscious side ; there is no Mediterranean fire here. Nevertheless this is a significant release and a vote of thanks is
due London Records for its superior contribution to Handelian art.
not
al
curve
for -the
future
but
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Circle 64B
AUDIO
64
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH,
1956
PATENTS
(from page f)
U r Are tliAt 6s-t,A*1-1(
of your claims. If you do, you are entitled
to appeal to the Board of Appeals, cornposed of nine Examiners -In-Chief plus the
Commissioner and his Assistants. If this
fails and you are still of the same mind,
you can go before the Court of Customs
and Patent Appeals or take other legal
No longer is it necessary to consult
a r tion.
It
is pretty obvious that the examiners
who do the day -to -day work of examining
applications and either allowing or re-
is best.
testing organization continues to acclaim the ESL Professional and Concert series
cartridges as "by far the finest phonograph reproducing instruments."*
The details of these tests are available from ESL without cost. Hear the
sensational new ESL electrodynamic cartridge at your audio
-
AU )10
which pickup
again reveals ESL in first place. America's authoritative high fidelity
jecting claims are the backbone of the
Patent Office and the most important indi-
vidual to most inventors. It is usually on
his sole responsibility that your invention
does or doesn't result in a patent and that
your allowed claims give you or don't
give you the protection you want and
ought to have. While he can be wrong
and knows it -and will read your attorney's arguments with an open mind and no
personal axe to grind, his is usually the
final word, since few cases are appealed.
And since few companies or individuals
would spend a great deal of time and
money inventing if they did not feel that
they could get protection, the examiner's
actions have a very direct and profound
influence of the entire advance of technology. This is as much true for the largest
companies as for the most insignificant
individual inventor, for the examiner is
as impartial and careful with one as with
the other.
Obviously, an examiner gains a tremendous education in doing his job. Not only
does he examine applications for patents
on the newest developments, but Ile must
also spend a good deal of time reading the
literature and referring to other patents
to be sure be does not allow a claim which
should have been rejected. Of all the engineers and scientists in the country, a patent
examiner is probably one of the most
knowledgeable. Though the Patent Office
doesn't like it said because this is a way
of losing valuable examiners, many of
them have stepped into advanced positions
in industry, a move made possible by their
encyclopedic knowledge of their subjects
gained on the job. And the job especially
app iota to men who don't like "routine"
routine"
or tasks which keep their noses to the same
grindstone day after day. An examiner
finds a new problem with every application
be picks up, one on which he must use his
pow ere of analysis and reasoning; there
is nothing automatic or routine about looking into another man's mind and making
a fair, learned, and complete answer to
his arguments.
An examiner requires, of course, a great
deal more skill than any new employee can
be expected to have. While there is no
training school or course in the Office for
the people who are employed as examiners,
training tasks are assigned to new people
which over a period of years train them to
do the very responsible work independently. As a matter of fact, recent surveys
have shown that the average examiner does
not reach his full value until after eight
years of experience in the Office. A new
man or woman turns out only about 31
per cent as much work as an experienced
examiner in terms of applications finally
disposed of.
a swami to discover
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the 3vd
Reprints of articles which appeared in AUDIO
from July 1952 to June 1955. 124 pages of articles of greatest interest to the serious hobbyist.
The AUDIO ANTHOLOGY and 2nd AUDIO ANTHOLOGY
are no longer in print.
-
CUT OUT
MAIL TODAY!
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Radio Magazines, Inc.,
P.
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Gentlemen: Enclosed
is
copies of
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check
money order for $
.
the 3rd audio anthology (paper cover)
the 3rd audio anthology (board cover)
Please
send me
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Zone
State
s;nunnaua.uaua..aaauuanuunanuuuuaauu.a.naaauaan.nu.n.aaunnaanu.n.uummuutnaawnuuuuuuuunn..auauuaaatnnnu.untt.
MARCH, 1956
65
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AT HOME WITH AUDIO
'Dynamic BT' and
Watts, Too!
12
It's here at last! A 12 watt high fidelity amplifier with
built -in pre -amp incorporating the amazing "Dynamic
B-T" (continuously variable equalization on both Bass
and Treble).
You've got hear for yourself what "Dynamic B -T" con
_do. Ask your dealer today to let you listen to the new
Munston HF -1 2. You'll be amazed!
Twenty -four hours later
20 cycles to 20,000 cycles ±1/2db
FREQUENCY RESPONSE
--55
HUM & NOISE
HIGH LEVEL INPUT
LOW LEVEL INPUT
70 db below
db below
EQUALIZATION
_
MUNSTON
TONE CONTROL
munston
/
9mv, 30mv, t /v, '/2v or more on
tape, auxiliary and tuner
ON PHONO
-5
BASS
db to
TREBLE +7 db to
DYNAMIC
the
continuously variable
INPUT SENSITIVITY
DYNAMIC TONE CONTROL
full rated output
full rated output
-27
ON TAPE
BASS
db
TREBLE +10 db to
MANUFACTURING,
-15
db at 20 cps
db at 20,000 cps
HF -12
$7950
to +13 db at 20 cps
Beech
INC.
+27
-18
db at 20,000 cps
Street, Islip, Long Island, New York
Circle 66
-Keep i,t/o,'te(1- Pea cl
ELECTRONIC MUSICAL
INSTRUMENTS
By
Richard H. Dorf
In one big volume, you can now learn all
about the intricacies of commercial electronic
organs, including the Allen, Baldwin, Conn sonata, Hammond, Minshall- Estey, Lowrey
Organo, and others, together with many
smaller instruments. Constructional details on
the author's Electronorgan and the simpler
Thyratone show you how to build one of
these fascinating instruments for yourself.
A compilation in book form of the author's
articles in Radio Electronics, brought up to
date and with many additions. Price $7.50
(Foreign, $8.00)
.
Customary discounts to dealers and distributors
RADIO MAGAZINES, INC., Book Division
Please send me
N
a
P. 0. Box 629, Mineola, N. Y.
copies of Dorf's ELECTRONIC MUSICAL INSTRUMENTS I enclose check
money order
for $7.50 each
(Foreign, $8.00) .
me
Address
City
Zone
a
thin
The surface was then sanded again, very
lightly, with a #0000 paper, and a second coat of shellac applied. Twenty -four
hours after that, one coat of Super Valspar
varnish was applied, allowing 48 hours before sanding this coat down. A second
coat of varnish was then applied, and
another 48 hours later the surface was
rubbed down with a combination of crude
oil and powdered pumice. This, plus plenty
of elbow grease, took the high glossy sheen
off the varnish and gave the cabinet a
smooth, satin finish. Two coats of wax
were then rubbed in and the job was done.
The same finishing formula was used on
the strips of molding.
. This is where the tape ran out
Ends above the reader's communication,
continues below our rounding -out com-
12 watts
0.5% at full rated output
DISTORTION
I applied
coat of pure white shellac which was diluted 50 per cent with denatured alcohol.
SPECIFICATIONS
POWER OUTPUT.....
(,front paye ;26)
State
mentary.
The Compatible Speakers
This version of the Bozak B -305
three -way system now consists of two
B -199A woofers and the B -209 midrange unit. As the entire Bozak system
is power rated at 30 watts, response of
35 to 16,000 cps with 6 db- per-octave
crossovers at 800 and 2,500 cps, the
substitution of the Altec - Lansing
tweeter II- 808 /802 -B driver, with the
same low crossover point and the same
power rating, is happily and for all
practical purposes, workably identical
with the Bozak system and its own array of tweeters, as catalogued. (Fig. 11).
Wherefore, a group of music lovers and
a technician or two were called in to
help balance the system. To do so, they
went off instruments pretty much and
landed the hi -fi craft by ear -beam, to
the strains of some fresh, brand -new
recordings.
Particularly useful was the Fritz
Reiner -Chicago Symphony version, on
RCA -Victor's LM -1807, of the dynamics-filled Ein Heldenleben, in which
Richard Strauss's towering, fruity tuttis
(all the T's crossed, all the I's dotted)
and solo tootlings have been given the
full -range recording technique they deserve (something like 30 to 18,000 eps,
according to the text on the record
sleeve). Passages were played over and
over again as heads were bent forward,
ears pointed at their keenest to judge
the sound fairly, particularly the highs
which unmistakably needed pegging
downwards. To what degree, was determined in fairly short order. In the
best judgment of the group the most
satisfactory listening level, for that
room, was established at point 30 on the
dial of the 15 -ohm Clarostat CIT-pad,
along an arc calibrated from 0 to 100.
This, we are told, proved to be attenua-
AUDIO
66
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MARCH, 1956
' -PAD
(nos shown) is
inserted in leads to 8025 Drive,
ALTEC
H808 HORN
8028 DRIVER
BOZAK
B
-209
(16 ohm)
00
1.1 mh
(2.5yf
BOZAK
B-199A
er'ÖÖ
TO AMPLIFIER
4
öti
3.15 mh
(16 ohms)
Fig. 11. Schematic of three -way speaker
system shows wire -up and values of components. It is also plan of physical place-
ment of speakers within and atop of
infinite baffle.
tion enough for this unison of speaker
components to sing out both decorously
and fulsomely, as mood willed and ear
could accommodate -without disturbing
the neighbors.
Hi -Fi Disciples Are Made
The impact of hi -fi might be nowhere
so dramatic in effect, to begin with, as
in listening to the faithfully rendered
repercussions of percussion instruments.
The fledgling hi -fier's interest is pegged
at the percussion level. It is such a new
experience. He is real gone on concentrations of such instruments: their
boom and bang, the zing and the ping.
He is the sonic harrier, so to speak, who
learns to track down the same sounds,
familiar but dispersed, modified and secondary, along entirely new musical terrains. Anyway, play the music any
kind-and it will be appreciated and
loved for as many different reasons,
and at as many levels of comprehension
-
PREAMPLIFIERS
(from page 49)
for the bass and 3,000 cps for
tht treble. In any case the way not to
judge the "effectiveness" of a tone con-
as there are people. In these early stages
of hi -fi -ness, the system components are
(justifiably) bought by fame -of -name
mostly, letting their fitness in a given
home environment be what it may. Later,
having lived at home with audio and
feeling more at home with hi -fi the
gentler, profounder and perhaps more
enduringly satisfying joys of symphony
and quartet, concerto and sonata, oratorio and opera -flower slowly to genuine
appreciation. And with that gladsoine
attainment may come the need for reappraisal of the hi -fi baggage of our
first voyagings to the moon. As in
the speaker situation described above,
change in equipment, if then advisable
and affordable, equips us for the greater
adventures. Your dollars, spent more
purposefully, then get you equipment
engineered, designed and made to serve
you well, with close to professional
standards of precision, in terms of your
own place. At this point it behooves us
to report that the subject hi -fier of this
month's chapter of at home with Audio
is that pleased with his new speaker
system of best fit for him that he has
declared a budget of a few hundred dollars to buy more recordings of the classics including the moderns. Seems to us
to be a giant step, this, with more than
seven -times -seven league boots
from
novice to devout, music- loving, seasoned
hi -fi enthusiast.
It isn't exactly a wild talent, this one
of discovering and loving music through
a sort of home -study course in sound appreciation, after having played the
game of hi -fi sound aces wild, so to
speak. What you then get of greatest
value is a sizable piece of peace of mind,
all conditions being equal. For you have
reached the point of pleasantest returns:
through knob and switch and jack you
are able to commune at will with the
works of the masters written down in
the universal language of musical notation. The hi -fi controls are a means to
your happy hi -fi endings which, of
course (because we have plastic and impressionable minds, and hi -fi innovations
get through to them) are forever beyond
reach.
Or, as our headpiece would have it,
there's no hi-finality, exclamation point.
-
usually have a less dramatic but far
more musical effect, even in their extreme positions.
500 cps
Loudness Control
trol circuit is to twist the knobs all the
way in each direction and to see how
unnaturally screechy and boomy the
sound can be made. Tone controls which
really work where they are needed,
without unduly affecting the mid -range,
We have seen, in discussing the
Fletcher- Munson effect, that as the overall volume of sound is decreased our
bass hearing sensitivity is reduced significantly. In listening at volume levels
lower than that of the original music,
then, the original tonal balance will be
AUDIO
Ili
.
This
.
.
i.'
Mr. Ili Fi
It . .
The
.
BRADFORD
Perfect BAFFLE*
Radically new idea in loudspeaker enclosures. Not a bass reflex or folded horn.
The primary purpose of a loudspeaker enclosure is to prevent destructive sound cancellation
that takes place at low frequencies, when the
front and rear waves, emanating from both sides
of the speaker cone, merge.
It is obvious that no rear waves can escape
through a totally enclosed cabinet, and it would
be the perfect baffle, except for one reason. The
air pressure within the cabinet acts
as a cushion
and therefore restricts, cone movement.
upon,causes
loss of life and color.
This
The BRADFORD Perfect BAFFLE is totally
enclosed, yet it relieves cone pressure by ors
ingenious device that operates in unison with
cone movement.
Since this action conforms to au ultimate
scientific principle the BRADFORD Perfect
BAFFLE is the only enclosure that can give you
the utmost in sound reproduction.
.
And that, specifically, is .
ALL THE BASS, full, rich, clean bass, clearly
distinguishing each contributing instrument,
down to the lowest speaker frequency.
NO BOOM. Absolutely no boom. Boom, or
"one note" bass, is not high fidelity.
NO FALSE PEAKS. Does not "augment" bass by
false peaks that are really distortions.
ANY SPEAKER. Accommodates any speaker
...
any size, weight, shape or make.
NO TUNING. No port tuning or speaker matching.
ANY POSITION. Operates in any room position.
NO RESONANCES. No false cabinet or air resonances.
COMPACT. Four sizes for 8 ", (0 ", 12" & 15"
weaken. Baffles only 2" larger than speaker size.
Prices: finished, $39.50 $39.50, $59.50, $69.50,
respectively. Unfinished birch, $34.50, $39.50,
$49.50, $59.50.
REAL HARDWOODS. In all popular finishes
mahogany, blond, ebony, walnut.
INCOMPARABLE
made, hand finished
All walls s//" thick.
CONSTRUCTION.
...
...
Hand
by master craftsmen.
GUARANTEED. Unconditionally guaranteed to
out-perform any other enclosure now available
regardless of size, weight or price.
If you want the very best speaker enclosure and will not be misled as to real
performance by deceptive size or price,
see your audio dealer at once. A demonstration will convince you. Or write for
literature.
Prices slightly higher west of Rockies.
Patent pending.
BRADFORD
PeeGt
BAFFLE
BRADFORD & COMPANY
27
E.
3Sth St.
NEW YORK 16, N. Y.
67
MARCH, 1956
www.americanradiohistory.com
AmericanRadioHistory.Com
changed, and we should be able to introduce compensatory bass boost. Some
people like to do this themselves, with
the bass control; others like to have it
done automatically, by a bass boost circuit tied to the volume control. In the
latter case the volume control becomes
a "loudness" control.
SAVE
25%
Control Units
This is our
GROUP SUBSCRIPTION PLAN
Now you, your friends and co- workers
can save $1.00 on each subscription
to AUDIO. If you send 6 or more subscriptions for the U.S., Possessions and
Canada, they will cost each subscriber
$3.00 each, 1/4 less than the regular
.Jne year subscription price
Present
subscriptions may be renewed or extended as part of a group. Remittance
to accompany orders.
AUDIO
is
HOW LOUD IS SILENCE
Audio
Broadcasting equipment
Acoustics
Home music systems
Recording
(from page 19)
Conclusion
Renewal
Name
Address
Renewal
Name
Address
New
Renewal
Name
Address
New
Renewal
Name
Address
New
Renewal
Name
Address
New
Renewal
U. S.. Possessions, and Canada
only
RADIO MAGAZINES, INC.
0.
Box
To insure peak performance from all
audio systems; for correct adjustment
and maintenance of AM and FM receivers and transmitters; checking linearity of film and disc recordings and
reproductions; checking phonograph
pickups and recording styli; adjusting
bias in tape recordings, etc.
generator section produces the
mixed low and high frequency signal
The
required for intermodulation testing.
meter measures
analyzer section
A direct- reading
the input to the
MEASUREMENTS
CORPORATION
o
629, Mineola, N. Y.
the biggest
The most favorable circumstances encountered in acoustical research laboratories up to the present time have not
been sufficient to justify an assumption
that the acuity of the human ear will
attain the region of Brownian movement
of the air. It must be borne in mind that
Curves (C) and (G) ptesented for
thresholds in minimum audible fields are
those of trained observers, sensitively
alert to the faintest sounds. Conceivably,
some human being possessed of phenomenal hearing may be able to approach these hearing limits. But as this
approach is made, it is well to remember that biological disturbances such as
the pulsing of the blood in the skin of
the auditory canal, or the coursing of air
through the respiratory organs will contribute to the masking of external noise.
Furthermore, presence of the Brownian
motion of the ear itself would, in the
final analysis, mask any motion of the
air. Under these circumstances, it would
appear that man will never be aware of
the turbulence of the air about him, if
the motivating force is the Brownian
motion.
BIBLIOGRAPHY
Stevens and Davis, Hearing, p. 110.
Wiley, 1938.
...
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JERSEY
EDITION
most authoritative
ELECTRONIC
BUYING GUIDE
OFFICIAL REFERENCE SOURCE
Electronic supplies for research and industry. Not just
listings-but complete descriptions, specifications, illustrations and prices.
DOLLAR -WISE PURCHASING
-
Over
100,000 items
350
manufacturers in this industrywide MASTER catalog. Compare
specs and prices first
then
buy and save.
1456 pases
100,000 items
Complete descriptions
Specifications -Prices
11,000 illus.
(rations
JSO mfrs.
8 s 11 ", 6 lbs.
As
lowas
$295
r,or
»tins
d,,mumn
UNITED CATALOG PUBLISHERS. INC.
Ne Yr4
11e L
11
Circle 68B
AUDIO
68
NEW
Circle 68A
/ VeM"1956
print.
Name
Address
New
METER
Completely Self-Contained
Direct Reading For Rapid,
Accurate Measurements
results obtained by laboratory experimentation in the field of auditory thresholds, and the ultimate limitation by
Brownian motion.
Record Revues
New
INTERMODULATION
BOONTON
PA systems
(Please
MODEL 31
and indicates the percentage of
intermodulation.
still the only publication
devoted entirely to
P.
Control units performing the functions of preamplification and control of
bass, treble, volume, and record equalization are available commercially as
separate units, and also in combination
with the tuner, the power amplifier, or
even the record player. There is really
no inherent advantage of one scheme
over another, except for operating convenience, if the design is properly executed. Placing the control elements near
power transformers or phonograph motors increases the hum problem, but this
does not imply that the more difficult
solution will be any less satisfactory.
Measurements Corporation
MARCH, 1956
Your answer
to a low -cost,
well designed speaker!
NEW! Isophon
ELECTROSTATIC
TWEETERS
*
*
*
*
*
Better performance in higher
frequencies 17000 -20000 cycles)
Extremely low cost
Compact, space- saving
Easy Installation for single output
and push -pull amplification
Remarkable brilliancy of sound
TRANSFORMER DESIGN
(froua page 30)
(b) Keeping interprimary inductance
very low by using a bifilar winding technique usually increases the effective primary capacitance. Higher capacitance in
turn reduces the available power at low
distortion.
The performance is then quite analogous to that at low frequencies where
MANY SURPRISES
HIGHEST Fl
LOWEST PRICES
VA= Pe jPo/d
(45)
Analysis indicates, in a similar way, that
at high frequencies volt -amperes VAh
must be furnished (at high power levels)
in accordance with
VAA= Po +jPo /dh
(60)
dh= Xc /Rf.
(61)
X0 = effective primary capacitive reactance
We can now recall that capacitance, being basically a measure of length, has
where
and
proportionality
(82)
C: V'13: yy, /r
where V is volume and W the weight.
If K = 2, then W is reduced by 2°I r =
2.83 and the capacitance of the smaller
transformer is reduced by a factor 2112 =
1.41, almost a half octave.
(e) The combination of greater bandwidth, lower interprimary leakage and
lower capacitance can now contribute
substantially to the design of an economical high performance B, amplifier.
W./rltone
a
STHB7
Diam: 2.76"
Thickness:
0.55"
ST H
Size:
without pre-setting. RUMBLE WOW
and FLUTTER are practically npnexistant. Short spindle supplied for
use as HI-F1 record player. Plug -In
shells for all malt: cartridges.
Truly the greatest
with negative feedback would improve
the performance of a mediocre output
transformer. But, unfortunately, feedback amplifiers using such transformers
perform poorly at high power levels.
The writer has used small values of K
(in the range of 1.4-1.6) and maintained
adequate high -level primary inductance
for low distortion in conjunction with
grain- oriented laminations, and employed winding techniques common to
the traditional output transformer.
Tests on stable zero -source -resistance
(attained by controlled positive feedback) amplifiers with output transformers designed in accordance with the procedures outlined in this article confirm
the advantages stated herein.
6.30"
0.787"
(45 rpm
(from page 32)
gvathDtcb
ARNHOLD
CERAMICS, INC.
57th Street, New York 22, N. Y.
Circle 69A
AUDIO
spindle- Net
%11
DSVt
$59.50
$3.50 add'I.)
second instance is equal to that produced
by the single speaker in the first instance,
the more limited cone travel permits the
voice coil of each speaker to operate in a
more linear portion of its magnetic circuit,
reducing the harmonic and sub- harmonic
distortion in each speaker. Frequency response will be the name with one or two
speakers.
MARCH, 1956
/140 4C
-
DV scientists
have brought you new magic
the B80 A, professional anti -static
cartridges for ABSOLUTE FIDELITY.
(Pat. Pending).
Now you can enjoy static -free, dustfree, noise -free reproduction, longer
lasting records and prolonged stylus
life with a brilliance never before
dreamed of
Audiophile Net:
$ 9.78
Dual Sapphire
S 9.30
Single Sapphire
$21.30
Single Diamond
Micro Diamond St. Sapphire
$21.78
!
FREE!
1956 Wa- t'otre Catalog. The above are only samples of
the many terrific values in the new
1956 Fen -Tone Hi -Fi catalog including mikes, tape decks, cartridges,
record changers, silent listening
devices, etc.
AUDIO CLINIC
E..
HI -FI value ever!
Audiophile Net
For over a decade it has been known
that a low generator impedance obtained
5/16
Thickness:
1
AA
Limits of K
1.97"
x
.
Selected by all HI -FI authorities as
the most perfect Intermix record
changer ever built. Americanized
version of world-famous Rex A
changer. Patented Intermix -plays
10 In any size between 6" and 12"
FENTON COMPANY
15 Moore Street,
New York 4, N.Y.
Sold through better
Audio Distributors.
Soo
yours today
f
West of Rook lee,
prices slightly higher.
Circle 698
69
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part
901414s.buy
saw;
PHILADELPHIA SOUNDORAMA. Russ
Tinkham, .sa1,s manager for Ampex Corporation, Avery Pisher, president of Fisher
Radio Corporation, and Karl Kramer,
technical executive for Jensen Manufacturing Company. headed up emrthic,rts
part...what?
It is one thing to hear a few
bars of a sonata
whets the
-it
appetite of the connoisseur and
gives him a foretaste of future
enjoyment. But to hear half of a
complete symphony is more than
disappointing.
Yet, you can play a recording from
end to end and you can't hear ALL the
music unless your hi -fl equipment
includes a KELLY Ribbon "tweeter ".
Then, you can be sure that you've heard
that's on the record
for music's sake, add a KELLY
EVERYTHING
.
.
.
.
THE AUDIO EXCHANGE has the largest
selection of new and fully guaranteed used
equipment. Catalog of used equipment on request. Audio Exchange, Dept. AE. 159-19
Hillside Ave., Jamaica 32, N. Y. OL 8-0445.
AUDIO EXCHANGE EXCHANGES AUDIO
made
25 -50% DISCOUNT. Factory -fresh guaranteed LI' records. 694 and up; send 2204 for
catalogue. SOUTHWEST RECORD SALES.
Dept. A, 1108 Winbern, Houston, Texas.
SPECIFICATIONS
Frequency response
-3000- 20,0000 cps
-
6- ELEMENT BROAD-BAND FM ANTENNAS. All seamless aluminum. $10.95 ppd.
Wholesale Supply Co., Lunenburg 10, Mass.
Horn loading
1000 cps cutoff
Dimensions -81/2"
5Y
"x41/1"
x
-
View of the technical staff and equipment
in the control box at the Philadelphia
Academy of Music.
Force mass ratio
4 x 10- dynes /gm.
Aodlenhae
nt
$8935
complete with
crossover network
Write for complete information
KELLY'
on
reproducer.
UHF
AT LEADING HI -FI MUSIC CENTERS
ERCONA CORPORATION
(Electronic Division)
551 Fifth Ave., Dept.
New York, N. Y.,
A -3
Circle 70A
Please
IF YOU ARE MOVING
notify our Circulation Department
at least
5
weeks in
advance. The Post
Office does not forward magazines sent
to wrong destinations unless you pay additional postage, and we can NOT duplicate copies sent to you once. To save
yourself, us, and the Post Office a headache, won't you please cooperate? When
notifying us, please give your old address
and your new address.
Circulation Department
RADIO MAGAZINES, INC.
P. O. Box 629, Mineola, N. Y.
representing their respective companies at
an impressive demonstration of high- fidelity recording in Philadelphia's Academy of
Music on the night of February 13. The
Philadelphia Orchestra, conducted by Engene Ormandy was recorded both normally
and stereophonically on Ampex tape recorders, then played back immediately
through eight Fisher 50 -watt amplifiers
each of which was feeding a Jensen Imperial speaker system.
Approbation of the capacity audience
was ecstatic. The demonstration- concert
was produced by M. Robert Rogers, president of Washington's good -music station
WGMS, and general technical supervision
was in the hands of Thomas Tate, widely known symphonic broadcast engineer.
Other audio authorities who attended in
official capacities were Robert Paulson and
Melvin Sprinkle of Ampex, and George
Maerkle, James Parks and Prank Malley
who represented Fisher. Present as a technical consultant was William Chambers,
the well -known Philadelphia lawyer who
has built a national reputation for himself
as an authority on both of his hobbies
high fidelity and photography. Although
present at the Academy during the set -up
period in the afternoon, when speakers
were placed and levels adjusted, he had to
miss the concert itself in order to preside
at a meeting of the Philadelphia camera
club of which he is president.
-
PEOPLE AND STUFF. Lee Goodman,
vice-president of Precision Radiation Instruments, Inc., parent company to The
Radio Craftsmen, Inc., selected the Los
DESIGNED FOR THE BOOKSHELF
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FINISHED UNIT
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KARLSONITE
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Please send
copy of your
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"The Korlson
Enclosure"
(Model
SD
U
THERE'S A KARLSON FOR YOU
$3450
KARLSON ASSOCIATES, INC.
DEPT.
$4950
HIGH -FIDELITY SPEAKERS REPAIRED
Amp rite Speaker Service,
70 Vesey St., New York 7, N. Y.
BA 7 -2580
VARITYPING Composition, DSJ, IBM
paste -up, ruled forms, advertising layout and
technical matter in English and foreign languages. Catherine Rein, 874 Broadway at 18th
St., New York. GItamercy 7 -5720.
WANTED: FAIRCHILD TAPE MACHINE
PIC -SYNC MODEL No. 125 ONLY. Reeves
Sound Studios, Inc., 304 East 44th St., New
York 17, N. Y. ORegon 9-3550
AMPEX 400-A TAPE RECORDER, halftrack portable, $695 ; Electro-Voice 635 Dynamic Microphone and Stand, $35. Both guaranteed in Like -new condition, priced f.o.b.
V. R. Hein, 418 Gregory, Rockford, Illinois.
LOWTHER PM -2 driver, $115 ; Hegeman
enclosure, $75; both perfect condition. Other
speakers, enclosures. Write Hovland, 151 Hartford Tnpk, Hamden, Conn.
MUST SELL -PILOT AF -860 tuner, Gray
arm, Bozak 207A, Fairchild 65 -watt ambrand new, best offer. Box CM -1,
108 -C
p
FINEST IN HI -FI. Authorized distributors.
Any diamond stylus, $12.50, year guarantee.
We
today
pquirements.
your treeg
AUDIO UNLIMITED, Inc.,
169 W. 57th St., New York 19, N. Y. Opposite
r :unegie h all.
-the
TL'.\NI'l:li: iI Spec disc recording head
old field -coil cutter with long rubber damping
line. R. K. Morrison, 933 Colusa Ave., Berkeley, Calif.
ULTRA -FIDELITY
Dispersion Of The Highs
ASSEMBLED
PLYWOOD UNIT
SUI
uIlN.rnw
pr ward Ber Insertion fil'
aeMrtlulaseets: 250 per word for eweNwelal Mowtinsmith. Bates an set, and no Cement; rill be
allowed. City met be aeeampanled by rulttanee la
tell, ail net teeth the New Perk eau by the
Bret of the math weeding the Rate of lust.
so,
.
.
in England!
CLASSIFIED
105
B
WANTED: BACK COPIES OF "RADIO"
R. Scott, Powerhouse Road,
North Hills, Manhasset, N. Y.
MAGAZINE.
REL PRECEDENT Tuner,
Hermon. Virgil Foster, 17
Hermon, California.
260. f.o.b. Mt,
Ave., Mt.
Pine
COLLECTORS! 71 Edison disc records,
early pops, light classics. $1 each, $60 for all.
Send 104 for list. Box CM -2, AUDIO.
FOR SALE: 3 Western Electric 555 drivers,
;30 each;
Simplex
motion
heads, rear shutter, double bearing
intermittents, excellent condition, $175 pair.
John G. Bitel, 282 Ringwood Drive, \Vantage,
biroeo
1610 Neck Rood
Brooklyn 19, New York
(Model
Circle 70B
L.I., N. Y. SUnset 1 -8979.
AUDIO
70
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
PROFESSIONAL
DIRECTORY
CINEMA'S
TAPE AND FILM
ea ausser
CLEAN ERASURE
I OF
MAGNETIC TAPE & FILM
Angeles High Fidelity Show as a propitious occasion for previewing the new
Craftsmen Model CT -2 AM -FM tuner and
the companion Model CT -3 amplifier .
Cap Ziertaff has been appointed president
and general manager of Kierulff Electronics, Inc., and Kierulff Sound Corporation, Los Angeles. The entire electronics
industry tenders its best wishes to a great
guy in his new job.
NOW ULTIMATE
PERFECTION
IN TONE ARM PERFORMANCE
Ortho-sonic v/4
TRACKS
OF ORIGINAL RECORDING STYLUS
COURSE
J. Philip Worth has joined Cray Research & Development Co., Inc., as plant
manager ... Joseph P. Harris, president of
the Magnetic Recording Industry Association, announces the appointment of Mark
Mooney, Jr., to the post of executive secretary
Sanford L. Cahn has been named
to the same position with the Institute of
.
.
High Fidelity Manufacturers . . Arnold
K. Weber, who has been associated with
RCA and its predecessor companies since
1918, has been appointed director of manufacturing
. The entire audio industry
shares the sorrow of Carduner Sales Corporation over the passing of Eddie Klee man. associate and cherished friend for
more than twenty years.
.
VITAL ENGINEERING
PRINCIPLE SOLVED!
.
TYPE 9206 DEGAUSSER
á program erasure. Use the best.
Cinema's Bulk -Tank Type Degausser 9205.
Economically priced. Buy yours today.
Noise
,4-410,
CINEMA ENGINEERING
IIUI
CHESTNUT STREET
CO.
-RINK CAIN
`
Circle 71C
edrelvrudu,lly Si«ce 1944
1
I
iHOLLYWOOD
ELECTRONICS
DISTRIBUTORS OF HI-FI COMPONENTS
I
eve
.0 lus
lo,AngeleS46
lvll.
-WEble,38708
Call1
Circle 71D
HIGH -FIDELITY HOUSE
Most complete stock of Audio
components in the West
B. L. MacPherson has been chosen as
Western divisional sales manager for
Reeves Sounderaft Corp. Increased use of
Soundcraft magnetic products by the motion picture industry has prompted the
firm to open a new West Coast office at
338 N. LaFlrea, Los Angeles, according to
Prank B. Rogers, Jr., executive vice -president
. Election of Walter W. Slocum
as vice- president in charge of operatinns
of Daystrom, Inc., announced by Thomas
Roy Jones, president . . . John P. Jacks,
formerly catalog sales manager of Voice
and Vision, Inc., Chicago, has joined the
sales staff of Magnetic Recorders Company, Hollywood
. vioc Admiral Murray L. Royar, USN (ret.), has been elected
a director of National Co., Inc.
Avery Fisher of Fisher Radio Corp. has
been unanimously elected Chairman of the
Board of Directors of the Institute of
High Fidelity Manufacturers for the 1956
term. A charter member of IHFM, Mr.
Fisher has been active In all Institute matters. Among the many problems which will
be solved by the Institute during the coming year are those of show sponsorship
and the dissemination of high- fidelity information to the general public ... Harold
P. Cook has just been appointed to the
newly created post of director of advertising and market research of Tung-Sol Electric, Inc., and managers of three new sections have been named as his assistants.
They are: Robert M. Andrews, manager of
advertising and sales promotion for electronic products; Edward G. Hazeltine,
manager of advertising and sales promotion for automotive products; and Gerald
A. Morgan, manager of market research.
ATOMIC JEWEL
RADIOACTIVE
STATIC ELIMINATOR
Circle 71E
Improves Fidelity
At Your Dealer
//LCCK
featuring
REPRODUCTION
FLAWLESS
attained.
Stylus moves in straight line from edge to
center as in original recording.
INSPIRED
DESIGN:
Increases record life
. plays all
scratching possible
fits smallest cabinet
size records
...
.
.
.
no
all popular cartridges fit.
NEVER BEFORE in the history of Hi -Fi de-
velopment has the introduction of a
single component created such wide interest, laboratory and editorial endorsement.
Get ORTHO -SONIC V/4 with its 10 incomparable features.
ONLY 6444.50
At Better Hi -Fi Dealers Everywhere
WRITE FOR ILLUSTRATED LITERATURE
ORTHO -SONIC INSTRUMENTS, Inc.
66
B
Mechanic Street, New Rochelle, N. Y.
Circle 71A
Everything in HI -FI Sound Equipment
[
FEATURING
WVLLLL
MAGNETIC
WORLD'S FINEST
IEX
TAPE RECORDER
pCO.DIEf
SANTA MONICA SOUND
GRanite 8-2834
12436 Santa Monica Bled.. West
Los Angeles
25, Calif.
Circle 71H
Phone: RYan 1 -8171
536 S. Fair Oaks, Pasadena 1, Calif.
INDUSTRIES CORP. Bayside 61,
GIBSON GIRL TAPE SPLICERS
splices in a wink!
Reduces Record Wear
Reduces Needle Wear
ROBINS
the finest in Iii -Fi
Tracking error completely eliminated
NO SCISSORS.
HO RAZOR BLADES'
e
At Your Dealers
N. Y.
ROBINS INDUSTRIES CORP.
Circle 71)
YCAT,,
HIGH FIDELITY COMPONENTS
820
W.
Olympic Blvd.
L
TEL
.
15, Calif.
RI
INDISPUTABLY...
10211
Circle 71F
CANADA
High Fidelity Equipment
Complete Linee
Complete Stevie'
Hl -Pt Records
Components
and Accessories
-
&LECTROi)O10E
141
SOUND SYSTEMS
DUNDAS ST. WEST. TORONTO,
CANADA.
Circle 716
AUDIO
the world's best
microphones
Ask about the
new CM 51
shown here
(only 4 v2.
high), and the
famous U47M.
Write for ccm piece details.
SEE
US
Sole U.S.
\
Importer.
AMERICAN
ELITE. INC.
Dept. A
7 Park Ave.
New York 16, N.
Y.
AT THE I.R.E. SHOW IN BOOTH 839
Circle 71B
MARCH, 1956
71
www.americanradiohistory.com
AmericanRadioHistory.Com
COMPARE ON
A
SQUARE
the superior transient
response of
Jim Lansing Signature
extended range speakers
combination of tight electrical and rigid
mechanical coupling account for the exceptional transient response of Jim Lansing
Signature units.
A
Tight electrical coupling results from high
flux density and close voice coil tolerances.
Rigid mechanical coupling Is achieved by
use of a 4" voice coil with a 4" dural
dust dome attached directly to It. Thus,
cone area between coil and suspension is
kept relatively small; compliance between
coil and dome is eliminated.
when a 4" voice coil and
dome are used with a curvilinear cone,
a shallow piston assembly is made pos-
Structurally,
sible. This shallow form factor permits
better distribution of highs than would
a
a
deep cone.
James B. Lansing Sound, Inc.
manufacturers of precision transducers
2439 Fletcher Drive,
Los Angeles 39, California
VOLPAR PROFESSIONAL ARM
Acoustic Research, Inc.
Allied Radio Corporation
Altec Lansing Corporation
A M I Incorporated
American Elite, Inc.
Arnhold Ceramics, Inc.
Audak Co.
Audiogersh Corporation
Audio Specialties
64
72
39
47
Bard Record Company, Inc.
Bell Telephone Laboratories
Bradford & Company
71
71
69
54
51
52
16
67
British Industries Corporation
Brociner Electronics Corporation
Butler, B. B. Mfg. Co., Inc.
3
49
62
71
Cinema Engineering Co.
Classified Ads.
Collaro Record Changers
Discus Corporation
du Pont de Nemours,
Film Dept.
Dyna Company
Remember, only Jim lancing Signature
Speakers are made With 4" voice coils.
NEW!!!
ADVERTISING
INDEX
70
59
72
E.
T., & Co. (Inc.),
34, 35
59
65
Electro -Sonic Laboratories, Inc.
Cover 4, 12, 13
Electro- Voice, Inc.
71
Electro -Voice Sound Systems
70
Ercona Corporation
Fenton
69
Company
53
General Electric Company
Gray Research and Development Co., Inc 11
CIRCLE 72A
free!
ALLIED'S
1956 ELECTRONIC
SUPPLY CATALOG
324 -Page
Buying Guide
to the world's
largest stocks of
Electronic
equipment
33
Harman- Kardon, Inc.
57
Harvey Radio Co., Inc.
37
Heath Co.
71
High -Fidelity House
71
Hollywood Electronics
Hughes Research and Development Labor6
atories
2
Hycor Co., Inc.
Karison Associates, Inc.
Kierulff Sound Corporation
70
Kingdom Products, Ltd.
55
Lansing, lames B., Sound, Inc.
Leonard Radio, Inc.
Lorenz
72
63
55
Measurements Corporation
Metzner Engineering Corporation
Minnesota Mining and Mfg. Co.
Mullard Overseas Ltd.
Munston Mfg. Inc.
68
ALLIED RADIO
ALLIED RADIO CORP., Dept. 17 -C -6
100 N. Western Ave., Chicago 80, III.
Send FREE 324 -Page
ALLIED Catalog
mum
Tracking
10 Inch
12
"
14 "
14 Inch
2.7
2.1
17
21
"
"
Error*
2nd
Harmonic
Distortion
Index**
.5'
per inch
.4 "
.3 "
1.8'
"
"
Any Length $14.95
Direct from Manufacturer
Based on 12 Inch record
**The percentage of
2nd harmonic distortion, which is a function of arm design, is
directly proportional to the distortion index.
Write today
VOL PAR
4404 West 22nd Street
Panama City, Florida
CIRCLE 72C
newest
from
England
MONMRCH
8
71
15
43
7
71
61
Cover 2
60
Cover 3
61
48
71
71
1, 10
31, 45
58
...
Address
United Catalog Publishers, Inc.
68
City
Volpar
72
.shoe
Maxi-
Overall
Length
9
64
4
ZoNe
cartridge.
Pivot to
Needle
66
Triad Transformer Corp.
Tung Sol Electric, Inc.
Name
less
5
Pickering fi Company, Inc.
Pilot Radio Corp.
Presto Recording Corporation
Professional Directory
Santa Monica Sound
Shure Brothers, Inc.
Sonotone Corporation
Stephens Manufacturing Corporation
-
41
North American Philips Co., Inc.
Racon Electric Co., Inc.
Radio Craftsmen, Inc.
Rauland -Borg Corporation
Rek -O -Kut Company
Reeves Equipment Corp.
Rockbar Corporation
Robbins Industries Corp.
-all
71
Ortho -Sonic Instruments, Inc.
Ask for the leading electronic supply
guide to everything in Hi -Fi systems and
components; P.A. systems and accessories; recorders and supplies; TV tubes,
antennas, accessories; Amateur receivers,
transmitters, station gear; industrial electronic equipment; test and lab instruments; famous Knight -Kits, huge listings
of parts, tubes, transistors, tools and
books-all at lowest prices. Write for your
Free ALLIED Catalog today!
Extra low total mass -smaller stylus
load- tracks with less than one
gram vertical stylus force -exclusive
micrometer style counterbalance
nylon bearing surfaces to reduce friction and resonances-easy stylus inspection by simply lifting arm off base
-adjustable height-standard cartsatin aluminum
ridge mountings
finish -available in sizes listed below,
work
AUTOMATIC
RECORD
CHANGER
AVAILABLE AT
ALL LEADING DISTRIBUTORS
CIRCLE 72D
CIRCLE 72B
AUDIO
72
www.americanradiohistory.com
AmericanRadioHistory.Com
MARCH, 1956
How REK -O -KUT
Maintains
Quality Standards in
TURNTABLES
Subject: Induction Motors
The motor is probably the most important part of the
turntable. Yet, it is amazing how little information is generally
furnished about its performance. Examine most specifications.
and the only reference you may find is "4 -pole induction".
It is true that "4 -pole induction" is not to be ignored. It
is, at least, evidence of the use of a type superior to the 2 -pole
variety. But, there is more to a motor's performance than type
especially in this application.
The motor provides the necessary motion to the record.
But, it is also a common source of vibration, and a notorious
cause of rumble, wow and flutter. Unless the motor is built to
provide a smooth, steady flow of power it is virtually useless
for high quality turntables.
That is why Rek -O -Kut devotes so much attention to the
motors used in the Rondine and Rondine Jr. turntables. To
begin with, every motor delivered to Rek -O -Kut is subjected
to a rigid inspection. The motors are first placed on 'run -in'
racks, where they are permitted to run for at least 12 hours.
This serves as an effective check against over -heating, seizing
and general break down failure. If operating properly, this
warm up brings the motor to maximum efficiency ready for
speed measurements and other tests.
Bearing tolerances are carefully measured. Motors that
do not come up to Rek -O -Kut standards are disassembled and
rebuilt. Rotors are then tested for dynamic balance and corrective measures applied where necessary.
The next important step is to determine each motor's rpm
speed. This figure is then used to calculate the exact diameter
for each step on the pulley so that the pulley -idler ratios will
give the correct rpm for each record speed.
The grinding of the speed -steps on the pulley is one of the
most fascinating procedures in the entire process. In order to
assure absolute concentricity of pulley -to-motor shaft, the lam-
-
itex material of which the pulley is made is first drilled and
press -fitted over the motor shaft. The motor is then connected
and run so that the shaft and pulley material revolve as one
piece. With the motor thus acting as its own lathe, and the
shaft as its own center, the lamitex is ground down to the predetermined diameters. In this way, the pulley is absolutely centered and balanced on the shaft.
After re-checking, the motor is installed in a Rondine or
Rondine Jr. turntable. Shock mounting and acoustical filtering
are employed to isolate the motor from the chassis. The turntable is then turned on, and after the warm -up period (about
15 minutes) stroboscopically checked for speed. After speed
corrections are made, no further adjustments are necessary
except, possibly, after long periods of use.
The induction motor is only a small part of the story.
Rek -O -Kut quality control extends into every detail of turntable production. At other times we shall discuss the hysteresis
motor the idler and other parts, which influence performance. All to help you visualize and understand that quality is
a full time job.
-
X-
These are the REK -O -KUT
TURNTABLE
-
Reprints of this and other ads
in this series may be obtained
by writing to Dept. PC-1
R
EK -
O
(///(1-ff
3 -Speed
Rondine Deluxe with hysteresis motor
Rondine with 4 -pole induction motor
2 -Speed
Rondine Jr. Model L -34 (331/4 and 45 rpm)
Rondine Jr. Model L -37 (331/2 and 78 rpm)
(4 -pole Induction Motors)
-KUT COMPANY
49.95
49.95
38 -01 Queens Blvd., L. LC. 1, N.Y.
Makers of Fine Recording and Playback Equipment Engineered for the Studio
www.americanradiohistory.com
AmericanRadioHistory.Com
$129.95
79.95
Designed for the Home
9
Ih
s
htnr,lla
f
\
`Z
Combines
Best Features
of ALL Pickups!
..>
NEW IMPROVED 80 SERIES
ULTRA -LINEAR CERAMIC CARTRIDGE
THIS TRUE HIGH -FIDELITY cartridge embodies the most advanced
concept in pickups. Combines all the benefits of ceramic and magnetic cartridges (with none of the disadvr.ntages) in one pickup that fits any arm or
plug -in head! Enjoys absolute freedom from unwanted case resonance because of unique, die -cast housing. Not affected by moisture or humidity.
TWO BASIC SERIES. Standard Model 80 Series replaces most ceramic
or crystal cartridges. Model 80M Series provides replacement for all
magnetic pickups with no adjustments or circuit modifications required.
Here's Why You Should Use This
Completely New Ceramic Cartridge
SUPERLATIVE RESPONSE!
3'
HIGH COMPLIANCE! 3 z 10 6 cm, "dyne -several times
the average hi -fi pickup compliance.
20 to 20,000 cps.
INTERMODULATION DISTORTION! Less
LOWEST
than
at 18 cm sec.
NO PREAMP REQUIRED! Standard 80 Series works in
any amplifier input not having magnetic cartridge equalization. 80M Series works into any magnetic cartridge
inpul
HIGH OUTPUT! 80 Series, 500 millivolts. 80M Series, 25
millivolts at 5.5 cm sec.
NO HUM! Absolutely non -inductive. Nol sensitive
moisi and transformer fields.
to
NO
MAC-
STANDTYPE
80 Serins Tu rnnrer
Pickup l'rurides Extra Ben«lits. '1 \vo independent generating cartridges in one!
Euli power for stylus in
or resuse ... no distort'
onance front unused stylus.
7; -L-
ARD
MODIFICATION NEEDED.
NETIC
RECORD
SPEED
NET
STYLUS
E -V
MOUEL
REPLACE -
Single Play
Single Play
Single Play
Single Play
Single Play
Single Play
Turnover
SIS
8ISM
0.3M Sapphire
81D
82S
82D
84S
84D
85TD
81DM
82SM
03M Diamond
Turnover
86TD
86TDM
IM Diamond
48.00
'45,33,16 Talking Book
'45,33.16 Talking Book
16 RPM Extra Fine Groove
'45.33,16 Talking Book
'45,33.16 Talking Book
86TM
3M Diamond
1M Diamond
3M Sapphire
34.50
'45.33.16 Talking Book
Turnover
861
MENT
3M
82DM
3M
84SM
1M
84DM
1M
85TDM 0.3M
Sapphire
Diamond
Sapphire
Diamond
I M
Diamond
$9.60
23.10
9.60
23.10
9.60
23.10
48.00
Diamond
16 RPM
Extra Fine Groove
16 RPM Extra Fine Groove
78 RPM
78 RPM
78 RPM
78 RPM
NOTE: The numeral "4 "appearing in the model number indicates microgroove stylus; the numeral "2" denotes 78 rpm tip; the numeral "1"
denotes 0.3 mil extra tine groove tip. "D" denotes one or more diamond
stylii; "S" stands for sapphire stylus. Also 78 rpm Microgroove.
elLAI
LABORATORY PROOF OF EXCEPTIONAL PERFORMANCE
RECORD
RIAA
ORiNO
NO. 12-5 A9
Get the tacts! See your
11
I
''
4'61
01
1rr
)
1
4
5
II
Ill
distributor or mail this coupon today.
ELECTRO -VOICE, INC.
vylvil C
BUCHANAN, MICH.
Please send illustrated data on E-V 80 Series Ceramic Cartridge.
.1 iI
Nome
fI
67F0
-V
alr
lip-1111114Pi
11111
E
Address
14567891
Frequency in cycles per second
11,N1
i
MON
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Store
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