Audio magazine December 1954
DECEMBER, 1954
SOc
ENGINEERING
MUSIC
SOUND
REPRODU CTION
THE HORN-abuild-it-yourself article
THE JUKE BOX GOES HI-FI
TECHNIQUES OF MICROPHONE CALIBRATION
AT HOME WITH AUDIO-Hi-Fi a ) a Mode
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new type
gives you
50% MORE recording time per reel
••• on stronger, more durable
Mylar'
polyester film
With Type LR Audiotape, you
get the equivalent of a
ree/-and-a-ho/f of ordinary
tape ...
900 ft on a 5" reel
1 800 ft on a 7" reel
3600 ft on a 10%" reel
This new Longer-Recording Audiotape saves time and effort,
eliminates reel changes, gives uninterrupted continuity of recording and playback for any application where recording time
exceeds the conventional reel capacity.
Laboratory tests, as well as unsolicited testimonials by radio
stations and recording experts, have conclusively demonstrated
the superiority of LR Audiotape-in both performance and
durability. It is also important to note that the largest users of
longer playing tape are now insisting that it be made on
" Myl ar" polyester film, the base material used for LR Audiotape - additional proof of its superior quality.
Ask your dealer for a supply of longer-lasting, longer-recording
Type LR Audiotape. A copy of Bulletin No. 211, giving complete data and specifications on LR Audiotape, is yours for
the asking.
.Du Pont Trade Mark
Type LR Audiotape is made on
.a l-mil base of stronger, more
durable "Mylar" polyester film
- withstands extreme temperatures, is virtually immune to
moisture, gives maximum tape
life under all conditions of use
and storage.
AUDIO DEVICES, Inc.
444 Madison Avenue, New York 22, N. Y.
Offices in Hollywood - Chicago
Export Dept., 13 East 40th St., New York 16, N. Y., Cables "ARLAB"
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DECEMBER, 1954
VOL. 38, No. 12
Successor to RADIO, Est. 1917.
ENGINEERING
MUSIC
SOUND REPRODUCTION
C. G. McProud, Editor and Publisher
Henry A. Schober, Business Manager
Harrie K. Richardson, Associate Editor
Florence Rowland, Productipn Manager
Edgar E. Newman, Circulation Director
S. L. Cahn, Advertising Director
H. N. Reizes, Advertising Manager
Industry
"WfJrkhfJrse"
R epresentatives
H. Thorpe Covington and Dick Knott
Special Representatives
7530 North Sheridan Road, Chicago 26, Ill.
Sanford R . Cowan, Mid-West Representative
67 W. 44th St., New York 36, N. Y.
635
BROADCAST
DYNAMIC
MICROPHONE
West Coast
J. W. Harbison
Jam es C. Galloway
816 W. 5th St., Los Angeles 17, Calif.
CO NTENTS
Audio Patents-Richard H . DOTf ........ . ... .. .... . ... .. . . . . . . ... _ . .
New Literature . . ..... .. ...... .. .. . . . .. . .. . . . . . ..... . . _. . . . .. . . . . . . . .
London Letter-Richard A rbib ...... . ...... . . . .... . .. . ...... . .. . . .. . .
Letters
Editor 's· Report . .. ... .. . . . . .. ....... _. . ......... . . .. . ... . . . .. .' . . . .. .
About Music-Harold Lawrence ..... . ..... ... ... . . ........ .. .... . .. .
Evolution of " The Horn"- Edw ard V. Ketc ham, h . .... .... ... _. . .. ... .
At Home with Audio-Hi-Fi a la Mode-Lewis C. S tone . . . . ... .. . .. . .. .
Techniques of Microphone Cali bration-Alexis Bad11~ aieff . .. . . . . . ... ... .
The Juke Box Goes Hi-Fi-C. C. Mc Prmtd . . . .. . . . . . . .. .. . ... ... ... . .
Equipment Report-Craftsm en C350 Preamplifier- V -M Mo del 700 Tape. O-M atic Recorder-A 1111pex M odel 620 Amplifier-S peaker-Ronette
TO-284P Pickup Cartridg e .. . . ..... . ... . .. . . .. . . . .. .. . : . .. . ... ... .
Record Revue--Edward Tatnatl Can.by .. . . .... . ... . ... . ... . . . . .. .. . . . .
New' Products ... . ..... ... ......... . . . . . . .. .. .... . ... . ...... . . . .... .
Coming E vents . . . .. . . ... . .. . .. . ... : . . ........ .. .. ... . . .. . . , . . . ... . .
Audio ETC- Edw ard Tatnall Canb:y .. . .. .. .. . ... .. .... . .... . . .. .. . .. . .
Industry People ... . . .. . . . . . . . . . .. .. . ..... ... .... ... .. . . . ... : . . ... . . .
Annual Index ...... . .. . . . . ... .. . .. . . ... .. .... . . .... . . ...... . . . . . . . . .
Advertising Index .. . .... .... .. .. .. ...... . . ... . . . ... ... .. . . .. .... ... .
2
8
10
16
18
20
23
26
30
33
39
44
50
53
54
64
65,
68
./
AUDIO (titl. registered U. S. Pat. Olr. ) Is published monthly hy Radio Magazines, Inc., H;n;" A. Schober, PresldeDt;
C. G. MePtoud, Beeretary, E><eeutl•• and Edltorlal om... , 204 Front St.. MIneola. N. Y. SubscrlptloD rates---U. S. ,
P06Sesslona. Canada and Mexico. $4.00 ror ODe year. $7. 00 ror two years, all other cOuntries,· $5.00 per year. Single
copies 50e. Printed ID U. S. A. at RusIn ... Pr.... IDe.• 10 McGovern Ave., Lancaster. Pa. All rights reserved. Entire
eODteDts copyright 1954 hy Radio MagaziDes, IDe. EDtered as SecoDd Class Matter February 9, 1950 at the Post Omee,
LaDeaster. Pa. UDder the Act or March 8, 1879.
RADIO MAGAZINES, INC., P. O. Box 629, MINEOLA, N. Y.
AUDIO
•
DECEMBER, 1954
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AmericanRadioHistory.Com
TV
AND
Be
Uniform high .quality performance
day-a'fter-day in studio and remote
pick-ups has proved the rugged
dependability of the "635".
Exclusive E-V Acoustalloy
diaphragm assures smooth,
peak-free response 40-15,000 'cps.
Output is -55 db. 50-250 ohms
impedance selector, Tiltable head.
o/s n -27 thread. Cannon XL-3
connector. 18 ft. cable.
List Price $75.00
Normal trade discount applies.
See your Authorized E-V
Distributor or Write for
further information .
NO FINER CHOICE THAN
~kefu.*,e~
BUCHANAN. MICHIGAN
r------ --- - -- --- - - -------,
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AUDIO PATENTS
Engineering
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: WRITERS
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RICHARD H. DORF*
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for the second time
in four months or so, Patent No.
2,675,430, issued to Kenneth K.
Clarke of Chromepet, Madras, I ndia.
T his patent is the most cUl'ious combination of a doubtful inventi on and ext!·emely broad cla ims that I have ever
come across. I rather doubt that it will
work a t all in the fo rm shown, and from
some of the extrao rdinary statements
made in the specification, it appears possible that 'either the attorney who wrote
i~ or the inventor (or maybe both) ai'e
not overly familiar with either technical
electronics or tape recorders as they
exist and work. However, the idea behind it all is interesting and perhaps
useful, so here goes ~ecital of it.
The premise is that it may often be
desirable to take an existing tape recording and replace certain of the recorded material with new material. As
anyone who has tried it knows, it is
not always easy to erase certain rather
precisely located portions and dovetail
new material (parti cula rly music) in
wi th the old. The inventor's scheme is
to play the tap <? and when the instant
arrives at wh ich the new material should
begin to !'eplace 'H.!e old, the operator
punches a button, which places on the '
tape (or 'w ire) a- brief burst of oscillati on s ignal ef a frequency in the upper
audio range as a marker. Where the
new material should end and the old
resume, he again punches the button
<md a second marker _signal is recorded.
W hen the actual replacement of ma-
I
ENGINEERS, E. E. or PHYSICS
GRADUATES, for preparation
of technical manuals ...
HUGHES RESEARCH AND
DEVELOPMENT LABORATORIES'
expanding program for production of radar, electronic
digital computers, gU'[ded .
missiles and other military
advanced electronic systems
and devices requires the
following:
o
ELECTRICAL ENGINEERING AND
PHYSICS GRADUATES to prepare
operating, servicing and overhauling instructions for complex
electronic equipment. Those
with previous maintenance
experience on military equipment preferred. Writers will
participate in a three-month
program in our technical
training school to become
familiar with the latest Hughes
equipment prior to writing
assignments.
~ ENGINEERS EXPERIENCED in the
writing and preparation of
maintenance manuals for
electronic equipment or guided
missiles. These specialists will
work step-by-step with the
people designing, developing
and manufacturing the products
involved. Experience in the
writing of engineering reports
is of value.
* Au.d40 Can.sttltant, 255 W, 84th St.,
N c"<.r; Yarl~ 24, N, y,
I ___
,
-- ----------,
1
HOW TO APPLY
1
L __ __ _ ____ _ __ J
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,
I
terial begins, the recorder is switched
to the playback condition, aud the tap"
is started. When it comes to the point of
the first marker signal, a !'esonant ci rcuit in the special apparatus detects th e
marker and applies it to the grid of a
tube to the plate circuit of which is
connected a sensitive relay. This closes
the relay, whose contacts switch the
machine over to record. At the second
marker burst, the relay opens and th e
machine returns to playback. Presumably, the performer can thus listen to the
recording and synchron ize his singing
or talking w ith it up to the very instant
when the new material is to be inserted,
and a ll without any attention required to
switch the machine. Basically, it seems
a good idea:
It doesn't seem, however, to this lay mans mind, that it is the kind of idea
that constitutes invention, It particularly
does not seem the kind of idea that
merits allowance of claims which aJ!ipear to cover the entire field of using a
marker signal to change the machine
from pla.yback to record and vice versa ;
yet this is (with only slig ht oversimplification 011 my part) just what the claim s
seem to cover ! And the surprise is even
greater in view of the apparent impracticability of some featu res of the embodiment shown. Any engineer or in telligent technician could probably
remove the impracticabiliti es and make
it work, wh ich is my justifi cation for
presenting this patent, but the inven tor
didn't. Frankly, I am puzzled. But judge
for yourself . ...
Fig'lwe 1 shows the circuit, which
looks and is economical for the job it
HAVE JUST READ,
1
:
,
~B+
Z~
1 2 3
-----,
r------~~---r-~
,I
Write full details
of your qualifications to
I
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,,
,,
,
,
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HUGHES
1
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a:
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Research and Development
Laboratories
1
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SCIENTIFIC AND ENGINEERING STAFF
L
1
Culver City. Los Angeles County
California
Assurance is required that relocation
of the applicant will not ca use disruption
af an urgent military project.
1L __ _ _ _ _ _____ _ _ ______
1
I
1
~
1
1
1
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I
X
TO RECORD OR
PLAYBACK HEAD
____ JI
Fig. 1
AUDIO
2
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AmericanRadioHistory.Com
•
DE.CEMBER, 1954
Since 1935
the Garrard has been
sold and serviced
throughout the United State••
It is recognized every where
for superior
performance, ruggedne.s
and reliability.
"RIGHTS" and "WRONGS"
of record changer design
(Important In protecting ,our racvdll.
~
RIGHT:
Garrard Precision Pusher Platfol1ll •••
the only record changing device that Insures
positive, gentle handling of records wltII standard
center holes.
WRONG:
"Overhead Bridges" Cas on ordinary Chanlen)
••. which may damage or dislodge records
accidentally.
RIGHT:
Garrard removable and interchangeable
spindles ... Easily Inserted; accommodate all
records, all sizes, as they were made to be
played; pull out Instantly to facilitate removal of
records from turntable.
WRONG:
Fixed Spindles <as on ordinary changenl •••
which require ripping records upwards over
metallic spindle projections after pllylnl-
Other Garrard features include: 4 "II IIItIr
-no rumble, no Induced hum. "eiVY drill IIIaIt
-no wows, no waves • wel&bted tImItIII'-flywheel action, constant speed. mDt11ll11lltdl
-silence between records • silent ate.IIIc
stop-shuts off after last record; no disturbing
"plop". • .as, stylus weight Idjuslllllt-protects long·playlng records • ..Iance. ...ted
tone Irm-true tangent tracking. ualllnal_1I
-fits all popular high fidelity cartridges
s Finest Record Cho er
••• and this is the LEAK Tl/l0 HIGH FIDELITY AMPLIFIER
COMPLETE WITH "POINT- ONE" REMOTE CONTROL PRE·AMPLIFIER
Most economical amplifier ever built by
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the engineering skill and fastidious assem·
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admiration. Incorporates an ultra·linear 10·
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power output tetrodes in push·pull. Har·
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insuring flawless reproduction.
High damping factor of 23, and low hum level of
-76 db below full output, are ordinarily found
only in far more expen.sive units.
4 MASTER
CONTROLS
Mail coupon today for a complimentary
copy of "Sound Craftsmanship" 16
pages illustrating and describing all
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Control 1
Tuner,.Tape, AES,
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COL.LP
164 Duane Street
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Treble, 23 db
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Control 3
Bass, 23 db
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Contral4
On·Off and
Volume
EXCLUSIVE FEATURE: Tape recorder jacks (input and output) on front panels for instantaneous use
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WRITE FOR A COPY ' OF
"SOUND CRAFTSMANSHIP"
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Hame'------------------------;I
P'ease send "Sound Craftsmanshlpu to:
Address;__________________~_
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THE
are the only small size, all-purpose moving-coil
Oynamic Microphones that reduce the pickup of
random noise energy by 67%!
The Unidynes, 55s and 556s, simplify P.A.
installation; .. enhance your reputation ...
insure customer satisfaction by eliminating or
reducing callbacks due to critical gain
~ontrol
settings-often necessary when conventional
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'. ~
No wonder the Unidynes are used the World overmore than any other microphone
of any maKe, size, or cost!
does. S, is the function switch. In position 1 the device is out of use. In position 2 it is s1)pposed to record a marker
signal whenever button S . is pressed.
In position 3, the relay is operated when
a marker signal is received on playback.
Vi is the marker-signal generator.
V/ith S, in position 2, tube current flo\V ~
until S . is pressed. When S . is pressed
the tube is cut off, but, says the inventor,
current flowing throagh coil L continues
and oscillations are set up in the resonant
circuit L-C.. These oscillations are
coupled through C, to the record head.
S. may be a dashpot switch so that there
is a -delay after pFessure is removed and
the marker signa1 has a suitable duration. The oscillations' cease when Sf
opens.
Before commenting on the two outstanding question marks here, let us
refer to Fig. 2, redrawn by myself to
make what sense is available of the V,
circuit. The cathode is made positive
with respect to ground by voltage divider R,-R. from the B-supply. With Sf
open, the grid is at the same d.c. potential as the cathode, giving effectively
zerO bias (ignoring the probably slight
voltage drop across the resistance of
the coil L) and allowing plate current
to flow. When S . is closed the cathode is
obviously positive with respect to the
grid, and presumably the d.c. across R,
due to the B-voltage from R, is enough
to cause tube cutoff. So far so good.
But when this happens, how does current continue to flow through Land
cause oscillations at a frequency carefully defined by the inventor as ~ It
\/ LC? Does the shock excitation produce a train of damped oscillations? If
so, the Q of the Land C must be pretty
special at these frequencies (he suggests
10 to 20 kc) to shock-excite the circuit
into oscillations that will predictably
last long enough to operate the control
relay on playback.
Well , that might work. But obviously,
when the signals are placed on the tape,
the machine must be on playback so the
proper places for the markers can be
chosen. That being so, how are the
marker signals recorded? Apparentlyand this increases the mystery-the inventor has .in mind a recorder with a
single record-playback head.
When the ·new material is ready for
insertion, Sf' iin Fig. 1 is placed in position 3. The tuned Circuit is now con-
C1
+---4'(E---, OUTPUT
'"
a:
SHURE BROTHERS, Inc.
Microphones and Acoustic Devices
L-~_~_~RM1N-_~B+
S2
225 W. Huron St., Chicago 10, Illinois
Cable Address: SHURE'MICRO
Fig. 2
AUDIO
4
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•
DECEMBER, 1954
J
"18,000 HOURS
and slill ""ilhin specs';
says francis Brott, Chief Engineer, KOMO, Seattle
"Our first Ampex recorder showed us what a real professional machine
can do. After 18,000 hours of heavy use, the frequency response and
audio characteristics of our Model 300 head are still within the original
published specifications. This kind of performance sold us completely on
Ampex - that's why we've added four Ampex 350's."
•
NOW an Ampex for every broadcast need
With the addition of the new lightweight Model 600 series, Ampex now
offers your broadcast station a superior machine to meet every tape
requirement ... from distant field pickups to major network recordings.
For top-ranking performances and rehearsals and programs involving
extensive editing, dubbing and "spot" announcements, choose from
the Series 350 ... for recordings "on location" that assure studio fidelity
and accuracy, choose from the Series 600. All Ampex recorders have
the same basic head design ..
This new
Model 600
w~ighs 28 pounds
- price $498 ($545
including carrying case.)(A matching amplifier.speaker
unit, Model 620, weighs 16 pounds, price $149 . 50.)
THE ULTIMATE IN PRECISE TIMING WITH HIGHEST FIDELITY
Ampex timing accuracy is so excellent (-I- 0.2 %) that tapes are always
on speed - without program ' crowdings or cutoffs. Ampex reproduction
is so faithful that it is indistinguishable from a live broadcast - the result
of an unsurpassed combination of broad frequency response, wide
dync;llhic range and imperceptible flutter and wow .
....
ccepleJ as lhe d'ignalure ofdPer/eclion in CCape crnachines
CORPORATION
AMPEX
AUDIO
•
CORPORATION,
For a convincing demonstration, contad your Ampex Distributor today
(listed in Yellow Pages of Telephone Directory under "Recording Equipment")
Canodion General Electric Company in Canada.
Write today for further information and complete specifications; Dept. 8- 1880
934 CHARTER
STREET, REDWOOD CITY, CALIFORNIA
5
DECEMBER, 1954
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.
I N BLON D OR MAH OG ANY
THE
Melodist
by ALTEC L AN SING
In the few short weeks since this sensational high fidelity amplifier-loudspeaker
combination first appeared it has won praise from musicians and engineers
alike for its truly professional quality. The MELODIST is a brilliant performer,
. possessing remarkable quality in units so compact. A wide range of control satisfies
the most discriminating ear. The MELODIST offers world-famous
Altec Lansing quality at surprisingly moderate cost.
It is simple to install and as easy to operate as any record player. No technical
knowledge is required. And its compact size and tasteful design blend with
any decor, make it a gracious addition to any room.
A-339A Melodist Amplifier
700A Melodist Speaker
D imensions : 13 x 4Ys x 9%
Dimension s: 22% x 11 )1,; x lOY.
Range: 20-22,000 cps
Range: 90- 22 ,000 cps
Power: 10 watts , less th an 2% t. h.d.
Power Capacity : 20 watts
Imped ance : 8 ohms
Impedance: 4, 8, 16 oh.ms
Inputs : 1 for mag. phono or mic .
Components : 10" b/tss speaker , high
2 for ceram ic , crystal, tape or t uner
f requency speaker, multicellular horn,
Volume: 3 individual volume adjustments
3000 cps divi ding network
Loudness: compensated loudness cont rol
Price : On ly $99.00
Tone : Treble, 15 db boost or droop, 10,000 cps
Bass, 1:\ db boost or droop, 50 cps
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Crossovers : European , LP , old RCA ,
Visit your d ealer t oday.
new AES (NARTB , RIAA , RCA
Lf!t the MELODIS T intro duce you to
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new worlds of lis tening ple asur e.
Price: Only $129.00
.gm
nected to the grid of V" which is cathode-biased in _the normal mannel' by R •.
the bias value fixed at close to cutoff.
When the first marker signal comes
along it is detected by the tuned circuit
and the plate current of V . increases.
This actuates the relay, causing the machine to go to the record condition while
the new material is recorded .
The relay is specified as a type which
will now remain actuated, even after the
marker signal passes, until either (1)
another marker comes along or (2) Bplus is removed. Condition (1) can be
satisfied with an "impulse" relay which
alternately opens and closes on receiving energy. These are well known,
though not usually in the plate-circuit
types. Condition (2) can be satisfied by
using an ordinary relay with an ext ra
set of holding contacts, also a standard
arrangement. But offhand I can't think
of any type that will satisfy both requirements. T hey may be possible, but
I doubt that they exist now. The idea is
that the second pulse will return the recorder to playback a utomatically at the
point where the new material should end.
But with a two-head machine, the
tape hit:, the erase head before it passes
the record-playback head . Of course.
being in the record condition it couldn't
play the marker signal into the resonant
circuit anyway. But even if it could,
the marker would, like all the material
to be replaced, pass t he erase head first
and be erased before it ever reached the
record-playback head. This could only be
overcome with a three-head machine,
with the heads rearranged so that the
tape would pass first the playback, next
the erase, and finally the record head.
Among the uses cited for the invention is adding a "harmony part" to a
previously recorded vocal rendition by
superimposition. This is done simply by
using the invention as described. We can
charitably assume that the erase head
is to be disconnected for the purpose
though the inventor doesn't say so. But
even so, what special prov ision prevents
the bias from partially erasing the previous vocal ? T here is no indication of a
need for anything of the kind.
A s I said at the beginning I have
presented this patent because I think the
idea is good and probably it would not
be hard to design a workable embodiment of it. But I am sticking my neck
way out in being caustic about the flaws
I think are shown in the patent. Maybe
I am just displaying my own ignorance.
But if I am right, I hope I have succeeded in e:x;pressing shock and distaste
at the allowance of 13 big, fat patert
claims on the basis of an embC" ~; imell .
that may not work, of an ide;>. t hat 1t
seems to me any engineer con:cl hav{'
and probably would have conceiyec (and
most likely did) if the desire or necessity of achieving the stated results ev ~ r
a rose .
You can look this one over yourself
at a cost of 25 cents remitted to The
Commissioner of Patents, Washington
25, D. C.
AUD IO
6
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AmericanRadioHistory.Com
•
DECEMBER, 1954
AUDIO
•
7
DECEMBER, 1954
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AmericanRadioHistory.Com
TAMMOY
I
NEW LITERATURE
• Cinema. Engineering" Compa.ny Dlvislon
of Aerovox Corp., 1100 Chestnut St., Burbank, Calif., has available two new catalog sheets for distribution to interested
engineers. One covers Cinema hermetica lly-sealed resistor networks, while the
otner covers the new Cinema "PW" resistors for automation and printed wiring.
Both publications may be obtained direct
from the factory or through its author·
ized representatives.
• Heath Company, Benton Ha,rbor, Mich ..
i;; now distributing its new catalog for
1[055, the largest and most complete cata·
log the company has ever issued. Fea·
tured are seven new H eathkits, four radio
cally re-designed Heathkit models, and reo
styling of most of the remaining instru·
ments. In all, the new 4S-page catalog describes more than 55 kits, including test
instruments, amateur equipment, and
high-fidelity audio equipment. Copy may
be had by writing direct to the company
All the elements of a 'complete High Fidelity
sound system from the same manufacturer
The Tannoy organisation is the only single organisation on either
side of the Atlantic which designs and makes every unit in a complete
reproducing chain - from phono-cartridge to loudspeaker (and , when
required, loudspeaker enclosure). Small wonder that the Tannoy
Domestic Sound System, with eve~y unit really matching the next, has
given to ' high fidelity' the precise meaning it should have had all a long.
TANNOY "AUTOGRAPH" PRE-AMPLIFIER
wilh four switched inpuls, and swilched
correction for all major recording characteristics $95
TANNOY "AUTOGRAPH" PRE-AMPYfIER
with polished wood alld metal enclosure (or sland moul/ling $110
TANNOY HIGH-FIDELITY POWER AMPLIFIER
The perfect complement to the
Tannoy "Autograph" Pre-Amp'ifier
$150
TANNOY DUAL CONCENTRIC
HIGH FIDELITY SPEAKERS
12" 11I1il complete with crossover $130
TANNOY VARILUCTANCE TURN-OVER
CARTRIDGE wilh dual diamond slvli. $65
This, the Tannoy Organisation's latest
contribution to the realistic transcription
of recorded music, represents a technical
advance of some magnitude. Severa l conventions have been ignored, among them
the idea that if resonant peaks are kept well
outside the audio spectrum they may safely be neglected.
This cartridge has no uncontrolled resonances whatsoever. Tn addition ,
the lateral to vertical compliance ratio has had particular attention-and we
have not scorned empiricism in arriving at the damping arrangements
finally adopted. These factors, combined with very low effective dynamic mass
permit a completely safe tracking weight of six grammes at a ll speeds.
The turnover mechanism is simp le and pos itive, and the styli
assemblies are independent
TANNOY (CANADA) LTD.
TANNOY (AMERICA) LTD.
36 WELLINGTON ST., EAST,
TORONTO 1, ONT., CANADA
CARNEGIE HALL
NEW YORK 19, N. Y.
8
• Newark Electric Compllony, 223 W . MadIson St., Chicago 6, Ill., f eatures a com·
plete 64-pa ge high-fidelity section and the
la rgest listing of electronic items in the
company's 20-year history in its new 1955
catalog which is now being distributed.
Forms were held open until the last minute to assure inclusion of the latest
models of all manufacturers. Bound in
varnished-stock four-color cover, the catalog is Indexed by sections for easy reference to any product desired.
I
• CBS-Hytron, Danvers, Mass., includes
data on all miniature tubes, irrespective
of make, In the ' seventh edition of the
CBS-Hytron Reference Guide for Miniature Electron Tubes, which is now being
distributed free through CBS-Hytron distributors. Twelve pages of data i·nclude
329 miniature types 'Of which 7/J are new,
and 134 basing diagrams of which 27 are
new.
• B. B. Butler Mfg. Co., Inc., 3150 Randolph St., Bellwood, Ill., descr ibes and illustrates the many standard and specia l
types of ceiling, wa,ll, and corner baffles
in the company's line in a new catalog
which will be mailed free on request.
Baffles shown are for use with 6-, 8-, and
12-in. speakers, and -are designed for the
r a diation of sound evenly over la rge areas
when used in low-ieveillublic-address systems. Complete technical data, including
f r equency response curves, are included
with the description of each baffle. Also
in corporated In the catalog are trim
plates, mounting flxtures, speakers, and
transformers, with complete dimension s
an d prices.
• Federal Telephone and Radio Company,
100 Kingsland Road, Clifton, N. J., has
n .cently issued a publication of distinct
value to engineers in the form ,of a general cat a log covering Federal's measuring
a nd testing instruments. This line, introdu ce d to the industry for the first time,
incorporates many instruments which are
novel in concept of design and technique
of measuring. Many instruments are
drawn from foreign divisions an d associates of the IT&T System, an d from
leading instrument m a kers abroad.. Thi s
n ew Federal catalog should be in th e
h a nds of every design and d eve lopment
e ngineer. Request for copy should be d irected to' Rudolf Feldt, Instrum ent DiviSion, at the address shown above.
• The Willla.n1 Brand and Company, Inc.,
Willimantic, Conn., announces publica tion of a new Turbo Products Catalog
which combines easy-to-use features with
helpful information on wire and tubing,
an appendix which defines technical terms,
a nd tables of insulation resistance tem perature coefflcients, and temperature conversion. The product index r efers to 44
pages of specific informatio.n concerning
wires and cables, plastic tubing, a nd iden tification
111 a
rkers.
(Continued on page 53)
AUDIO
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•
DECEMBER, 1954
Binaural AM-FM Tuner
$169.95
HORIZON CRITERION
HORIZON 20
HORIZON 10
HORIZON 5
Matchless AM, drift-free FM,
both at the same time or new
binaural reception. Exclusive
FM Mutamatic Tuning eliminates hiss and noise between
statio11s! Phenomenal Sensitivity - .5 microvolts!
Revolutionary new UnityCoupled output circuit. Completely eliminates impulse distortion caused by transformers
in conventional amplifiers.
Unity-coupled output circuit.
Built-in preamp contn>l unit
with record equalizer, loudness
control, bass and treble controis - three inputs.
Less than .2 % harmonic, .3 %
intermodulation distortion.
Four inputs, 7 equalization
curves, loudness-volume and
bass and t'reble controls. Slips
into tuner or 20-watt am'plifier.
For complete specifications write Dept. A
THE CHRISTMAS GIFT THAT IS
llud1#
AUDIO
•
NATIONAL COMPANY, INC.
61 Sherman St., Malden 48, Mass.
ational$>
DECEMBER, 1954 .
www.americanradiohistory.com
AmericanRadioHistory.Com
9
iGnu~nu
iGrttrr
RICHARD ARBIB 6
A Complicated Hobby
get so complicated. Do you remember years ago as a kid, when you
took photographs with a Kodak. It
was very simple wasn't it ? You just pressed
a button, after 8 exposures you sent the
film to the local store, and within a day or
so had some prints back. If you then
progressed in photography you amassed
thousands of dollars-worth of equipment,
could not take any picture without lots of
gadgets, and often in the end waited weeks
UI~til you found time to develop and enlarge the prints. Furthermore, you were
never $atisfied. The same situation, to a
certain extent, appears to have come about
with records.
I remember distinctly the time when one
j ust took 8 or 10 records, loaded them on
to a machine, pressed a button and they
were played. Now, if you are a real enthu siast, you have to select the speed of record,
adjust th e mach ine and the pick-up to play
tht: speed and to be on the safe side, adj ust
the controls to comply with the correct recording characteristic., What you are supposed to do when you are playing several
records of different brands on a changer is
not quite clear because apparently as yet,
ther e is no automatic method of a ltering th e
reproducing characteristic to suit the brand
of record. However, if you are an addict to
the art, you may want to have a transcrip-
H
OBBI ES
'" Mn/ticore So lders, Ltd., Hrmei Hempst eod, H rrts. , Eng/o J/d.
tion motor and a separate pickup for each
speed and not allow the pick-up to actuate
an automatic stop as that might in some
way damage the styli or the record. It
seems that with hobbies the more advancer!
you get, the more complicated things become.
Having records in 3 diameters with :l
speeds and about 8 recording characteri stic~
has made the life of the audio enthusiast
quite complicated. The si tuation was reviewed most amusingly by O. J. Russell in
an article aptly titled "Stylus in Wonderland" in the October issue of the British
j ournal "Wireless World."
New Recording Tape Splicer
By the time this "London Letter" appear s in print, another device which shoul r!
be of assistance to tape enthusiasts, wi ll be
available in England. For nea rly 5 years
now your cO\Tespondent has been waiting
for someone in Britain to market a really
efficient tape splicer. Having waited in vain
so long he has now produced one which is
the subject of a patent. It incorporates the
best points of many of those that are marketed in America.
Styli Life
During recent months some attention ha~
been paid to the life of recording styli. With
a view to finding out what the Recording
Companies themselves recommend, ap·
proaches were made to both Decca anr!
E .M.I. Decca oh\'iol1s] y have the whu le
(Courtesy British Broadcasting Corporation)
BBC transcription recording unit~channel E, Maida Vale Studios. At the center are BBC disc
recorders, type D. At the right are two E.M.1. magnetic recorders, type BTR/ 2.
AUDIO
10
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•
DECEMBER, 1954
8·inch
5 watts
40·15,000 cps
$23.20
..• BECAUSE
THEY
SOUND
BETTER ...
Admittedly, the performance quality of
a/
10· inch
4·6 watts
20.20,000 cps
$68.50
loudspeaker depe·nds upon design and
. construction. But we know that you intend neither to design nor
build one. You will select one already designed and
built And when you sit back to an evening of musical enjoyment,
the chances are you won't be thinking of flux density,
impedance or cone suspension,
Certainly, the facts and figures are available for
Goodmans High Fidelity Speakers ... and we know
they will impress you. But, the pOint we make is that you
select your speaker as you intend to use it .. ,
not on paper but by critical listening. The more
critical you are, the more confident are we
that your choice will be Goodmans-for the best
reason in the world-because they sound better.
Complete Service Facilities maintained for your convenience
Sold by Leading Sound Dealers' Prices Slightly Higher on West Coast
For Complete Literature, write to:
ROCKBAR CORPORATION 215 East 37th Street, New York 16, N. Y.
AUDIO
•
12·inch
20 watts
30·15,000 cps
$72.95
11
DECEMBER, 1954
www.americanradiohistory.com
AmericanRadioHistory.Com
-
problem well in hand for a comprehensive
instruction sheet arrived without delay,
stating quite clearly that under normal
conditions a life of more than 36 hours
could not be expected for a sapphire stylus.
Information from E.M.I. was much more
ViJ,gue and they were not prepared to make
any definite statement.
It is significant that the new Leak pickup
is fitted only with a diamond stylus and the
Philips Group have now stated that all
their radio-g ramophones will be fitted only
' with diamonds.
Largest Recording Organisation in the
World
LIST $8.50
sapphire
n ee dl ~
•• • another first from
SONO...
NE
wide-range
high-compliance
single-needle ceramic -cartridge
Here at last is a high fidelity cartridge at a moderate price,
available in either of two needle sizesone for 45 and 33Ya rpm, _the other for 78 rpm.
Performance is at the same high level as the world-famous
Sonotone "Turnover."
Send coupon for free bulletin showing the exceptional specifications
of this new cartridge.
ELECTRONIC
APPLICATIONS DIVISION
SONOTONE CORPORATION
Elmsford. New York
,----------------------------------------------------------------------I
I
SONOTONE CORPORATION, DEPT. A
ELMSFORD, N. Y.
I
;
I
I
,I
Please send me free bulletin describing your new IP Cartridge.
NAM~F
___________________________________________________________
ADDRESS~_______________________________________ ApT. ___________
CITY------____________________~--~-------------STATLE-----------
------.---------------------------------------------------------------12
Probably the largest recording organisation in the World is the Recording Department of the British Broadcasting Corporation. Although this Department is
responsible for the maintenance and operation of 379 recording machines, they never
sell a record. The playing of commercial
reco rds is the r'e sponsibility of another
B.B.C. Department. The figures quoted
above exclude any sound recording activities of the television service of the B.B.C.
It must be remembered that in England
sound' broadcasting is excl usively undertaken by the British Broadcasting Corporation. Although most people think that the
B.B.C. is Government controlled, it is
actually appointed by Royal Charter to
undertake its task. The B.B.C., apart from
being responsible for the operation of a
number of programmes in 45 different
languages for overseas listeners, broadcasts
throughout the United Kingdom three different programmes; the Home Service;
Light Programme and Third Programme.
At the present time about 40 per cent of
the programmes transmitted through these
three channels which, of course, have various transmitters strategically situated
throughout the British Isles, are from re. cordings made by the B.B.C. In addition,
of course, a number of recorded programmes made by other organisations are
transmitted as are a controlled content of
commercial records.
The B.B.C. Recording Department operates in six centres in London. It has a
maintenance unit which keeps all the machines in working order and a section which
makes sapphire styli. Ten mobile recording
units are located in London and mobile and
static equipment is operated at twelve regional centres in the British Isles. In addition, recording units are maintained in th e
Middle East at Cairo, and in N ew York.
Wh il st the bulk of the Recording Department's activities are for the recording of
programmes to be broadcast subsequently
over the B.B.C. Home or Overseas Programmes, they also are responsible for the
Transcription Recording Unit. This section of the B.B.C. is maintained at the e~­
pense of the Government and not out of
the licence fees paid by users of radio in
E ngland. It is considered to be good propaga l~ da for the British way of life for complete broadcast programmes to be recorded
and despatched overseas for use free of
charge.
The Transcr,iption Unit at the moment
does all its distribution on 16-in. discs at 33il
r.p.m. (not microgroove). Experiments are
being undertaken with a view to changing
over to microgroove but before this could
AUDIO
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AmericanRadioHistory.Com
•
DECEMBER, 1954
AUDIO · .
f3
DECEMBER-~' 1~54-
www.americanradiohistory.com
AmericanRadioHistory.Com
Now Available Under
Acclaimed at the Sight and Sound
Exposition in Chicago and the
Aud~orama in New York, these amazing highfidelity speaker systems are now available under HTPan exclusive Permoflux insured plan that enables you to
try a Largo or Diminuette in the quiet and comfort of
your own home for 15 days. See your hi-fi dealer today!
'EXCLUSIVE PERMOFLUX 1S-DAY INSURED HOME TRIAL PLAN, INTRODUCED AT THE CHICAGO AND NEW YORK AUDIO FAIRS, O.CT., 19S4
be accomplished, there are technical problems to be overcome, with particular reference to cueing and also to ensure that the
hundreds of reproducers overseas are capable of playing microgroove records. Many
of these programmes are not just recordings of B.B.e. programmes but are ones
specially performed for overseas consumption. Other programmes are Home Service
performances with foreign language announcements replacing the English comI
ments.
A brief visit to Broadcasting House, the
centre of the British Broadcasting Corporation in Portland Place, London, and a
conducted tour by D. Winget, Assistant to
the Superintendent Engineer Recording,
was only able to give your correspondent
a very brief idea of the considerable activities of the B.B.e. recording organisation.
The recording is carried out by two methods, either disc or tape. Disc records are
made at either 78 r.p.m. or 33! r.p.m. ( not
microgroove.) The standard tape speed
now used by the B.B.e. is that of the
c:e.I.R. primary standard, i.e. IS-in. per
second, single track. For portable tape recorders a slower speed may be adopted in
the near future. In considering tape speeds
one problem with which the B.'B .e. has
to contend is the receipt of tapes from overseas broadcasting organisations, particularly those on the Continent of Europe. The
Germans like 30 in. per second; some tapes
arrive at n in. per second; some are single
track; others double track. In order to have
a standard for transmission, the B.B.e.
usually re-record overseas tapes if they are
not of the same speed of 15 in. per second
or of the standard B.B.e. recording characteristic.
(
Why Discs Are Used
THE LARGO
THE DIMINUETTE
Outstanding wide - range
speaker system at moderate
cost. Uses the "Super Royal
Eight" speaker and Super
Tweeter. Unique new-type
back-loading horn enclosure
is matched, octave by octave,
to speakers _ . _ assuring undistorted reproduction from
35-16,000 cps. In selected %"
Mahogany or Korina veneers.
Exclusive: Special connection
for headset extension cord.
Size : 24" W, 23" H , 14" D.
Impedance, 8 ohms.
A marvel of compactness featuring " big-system " repr()duction over the full audio
range and low cost. Ideal for
u e in a bookcase or as extension speaker: With 2 "Royal
6" speakers and Super Tweeter.· In Mahogany or Blbnde
finish 3,4" veneers. Size 23 y,"
W, 11 Yz" H, 12" D. Impedance, 4-8 ohms.
Suggested Audiophile Het ... $99.75
Suggested Audiophile Net ... $49.50
As above, but with selected
'Is " Mahogany or Korina venee~s.
Suggested Audiophile Net ... $64.50
HEARING IS BELIEVING! Try either system at horrie under HTP!
Read what High-Fidelity Magazine says:
"It's best to try a speaker at home before buying."
-Altdio Forum Dept., Oct. 1954 issue
Every HTP participant will receive, absolutely FREE, the new Permoflux "Maestro" Speaker-Headset Control
Box. See your Permoflux-authorrzed HTP dealer, or write for full
details, to :
FOR A LIMITED TIME ONLY:
pJlJvYn~
CORPORATION "
The tape enthusiast may well ask why
the B.B.e. should use disc recording at
all, but an examination of their problems
makes it clear that there is still a field for
discs. Whilst the proportion of tape to disc
at the B.B.e. is somewhat lower than one
would have thought, it is only due to the
fact that the B.B.e. engineers believe in
installing first-class tape equipment and
they cannot do everything in a snort while
for all expenditure has to carefully considered. The principal type of' static tape
machines used by the B.B.e. cost $3,000
each and when one realizes that 118 of these
are a lready in use, it will be appreciated
that changes cannot be made rapidl¥. However, new tape machines are being brought
into use practically every week and it is
thought that \~thin a year or s9 the general proportion of tape to disc recording will
be something in the order'" of three tape to
two disc.
The B.B.C. engineers ' are not satisfied
that tape has a good enough storing property for what they call their "Archive
Library." 'T hat is a library of programmes
or proformances of historicai interest
which, it is believed, should last practically
indefinitely. The B.B.e. engineers told me
that the German Broadcasting Qrganization keep all their Archive recordings on
tape, but to be on the safe side tfuey rerecord every , tape every five years. This is,
01 course, qUite a job and it means that by
the end 'of 50 years the tape has been
(C onlinued on page 58)
AUDIO
14
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•
DECEMBER, 1954
first in its power
range •• designed
specifically for
audio service
The Tung-Sol 6550 is a brand new and direct approach to the
high power design requirements of high fidelity audio amplifiers_
For outputs up to 100 watts, two 6550's in push-pull will provide
the same ,power now attained in most existing designs by the
use of four or more tubes. In 'addition to greater audio output,
use of the new 6550 results in simplified electrical balance, reduced maintenance and lower cost. The Tung-Sol 6550 is not
directly interchangeable with the 6L6, 5881 or KT66 class of
tobes. With proper circuitry, however, the 6550 will provide
full power output with approximately the same grid voltage
drive as the smaller tubes. The 6550 is produced under laboratory conditions with exhaustive quality control to assure premium
performance and. long life.
Rugged Construction - The advanced design features which
have made the Tung-Sol 5881 so e>rtremely reliable are embodied in the 6550.
1 Glass
2
3
4
'5
6
button stem construction is strong and compact and
provides a rugged support for the tube structure.
MiCanol 'wafer and metal shell base provides fuil lifetime
electrical insulation, and greater mechanical strength.
Cathode materials of exceptional stability give mare uniform emission with greater life expectancy. Cathode is n9t
poisoned by inactivity during standby periods.
Maximum control of grid emission achieved by gold plating
and carbonizing.
Triple gettering promotes lang, gas-free life. Getters are
confined by a ,spray shield to prevent mica contamination.
L,ife tests are made under severe overload conditions to
asslire adequate safety factor.
Outline Drawing
Bulb-Short St-16
Base
Large Wafer Octal 8-Pin Mical with Metal Sleeve B8-86
2'/,./1
Maximum Diameter
4%"
Maximum Overall Length
Maximum Seated Height
4'1,./1
Pin Connections
Retma Basing 7S
Pin 1-Base Shell
Pi'n 5-Grid No. 1
Pin 2-Heater
Pin 7-Heater
Pin 8-Cathade and
Pin 3-Plate
Grid No. j
Pin 4-Grid No. 2
Mounting Position
Any
ELECTRICAL DATA .
(INTE RPRETED ACCORDING TO. RETMA DESIGN CENTER SYSTE M)
DIRECT INTERELECTRODE CAPACITANCES -
Grid # 1 to Plate
Input
Output
•
0.85 p.p.f
14.0 p.p.f
12.0 p.p.f
RATINGS
Heater Voltage (AC or DC) .
6.3 ±10%
600
Maximum DC Plate Voltage
Maximum Plate Voltage (Triode Connection) •
450
40
Maximum Plate Dissipation (Triode Connection)
400
Maximum DC Grid # 2 Voltage
-300 to 0
Maximum Grid # 1 Voltage
35
Maximum Plate Dissipation
6.0
Maximum Grid # 2 Dissipation
175
Maximum DC 'Cathode Current
Maximum Heater-Cathode Voltage
Heater Positive (Peak) (DC not to exceed 100V) +200
-300
Heater Negative (Peak or DC)
50
Maximum Grid # 1 Circuit Resistance (Fixed Bios)
Maximum Grid # 1 Circuit Resistance (Self Bias)
250
250
Maximum Bulb Temperatute
VOLTS
VOLTS
VOLTS
WATTS
VOLTS
VOLTS
WATTS
WATTS
MA.
VOLTS
VOLTS
KILOHMS
KILOHMS
°C
HEATER CHARACTERISTICS
Heater Voltage
AUDIO
No Shield
DECEMBER, 1954
www.americanradiohistory.com
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6.3 VOLTS
LETTERS
Exciting High Fidelity Firsts!
T he Audio Fair
SIR:
Now . . . in these superb matched
instruments . . . enjoy "the foremost
advances in High Fidelity ... startling
realism, greater power, lowest distor·
tion, precision craftsmanship.
....
-•
INTERELECTRONICS
:::I
III.
"Coronation 100"
40 WATT
9950
Amplifier S
Greatest amplifier buy today and here's
why. RESERVE POWER - 80 watt peak.
EXCLUSIVE NOVALOOP CIRCUITRYcomple.tely new, non-ringing multiple
path feedback design, over 50 D8 'eedback. 40 WATT HIGH EFFICIENCY, WIDE
RANGE OUTPUT TRANSFORMER - sealed
multiple-section winding, thin strip core.
FOOLPROOF DAMPING CONTROL - continuously variable, exactly matches loudspeaker for startling performance. 5 .to
200,000 cycle response. DISTORTION FREE
-less than 0.05% at 30 watt level, ex-
ceeds FCC requirements for FM broadcasting. POWER RESPONSE-at 30 walls
± 0.1 DB from 16 10 30,000 cycles. HUM
AND NOISE LEVEL-virtually non-measurable. DESIGNED FOR THE FUTUREfinest sealed components mounted on
Bakelite terminal board for decades of
trouble-free listening pleasure. Plug-in
filter capacitor. Critical networks of precision components, lifetime encapsulated.
BUILT-IN PREAMPLIFIER POWER SUPPLY.
BUILT-IN POWER FOR NEWEST ELECTROSTATIC TWEETERS. Other firsts.
W ith the 1 ~54 A udio Fair relegated to
its place in history, an audiofan mulling
over his br iar in moody retrospect garners
the feeling that audio developments exhibited in the sparkling ar ray of new equipment
has so"mewhat fo llowed the trends evident
in the 1953 Fair. Refinements and improvements of known circuits and speaker enclosures together with the breath-taking
quality of many of the new records recently
produced by the progressive record industry
did, in most of the exhibits, provide thrilling r epr oduction close to but not quite complete satisfaction.
P ost impressions of the F air are that the
over-all "Fai r" sound generally lacked real
depth and bottom. The bass heard in many
exhibits sounded constricted or cut by the
limited size of cabinetry comprising tonal
depth for size ( evidently due to popular
demand) . In other words, the treble seemed
to be balanced by a loud high ba ss rather
than a solidly extended low bass. The big
jobs did sound better on the low end, but
even so any supporting bottom much below
50 cps was difficult to detect.
The horns emphasized again to the briar
puller that horn loading does provide the
most satisfactory type of loading for solid
"s pace-filling bass response. T he hitch th at
complicates matters, however, is that \ in
horns folded for space saving the path
length of the bass horn proj ection is usually
much longer than that of the t reble speaker .
P erhaps the time between now and next
year's Audio show of shows will produce a
horn speaker system with equalized bass
and treble path lengths responding solidly
and clean down to, say 30 cps, and just to
g ive the briar industry a lift let us set the
obj ective to retain the same bass-treble balance over the enti re reproduced dynamic
range.
S. L. H EIDRIC H,
29 Richmond Drivt.
Darien, Conn.
(See page 23- maybe that will help. Ed.)
Proposed New Audio Power Tube
SIR :
CONSOLETTE
o
....
..
:•
1M
"Coronation"
PREAMPLIFIER-EQUALIZER
Worthy companion to the incomparable
" Coronation 100" 40 watt ampliAer. AD ..
VANCED EXCLUSIVE CIRCUITRY - the
only preampliAer-equalizer operating entirely thru negative feedbac~. REVOLUTIONARY NEW INPUT TUBE, Z-729,
phenomenal low noise followed by premium 12AY7 tube. HUM INAUDIBLE with
all controls on full. DISTORTION FREEvirtually non-nieasureable, exceeds FCC
requirements lor FM broadcasting. 5 to
200,000 cycle response. HIGHEST GAIN _
no transformers required with all present
phono cartridges. LOUDNESS CONTROLcontinuously variable to' your exact pref-
For the hi-fi thrill of your fife,
hear the Coronation Twins todayl
Some dealerships still available.
erence . MAXIMUM BASS AND TREBLE
COMPENSATION - over 20 DB distortion-free boost and attenuation. FIVE
INPUT SELECTIONS. 16 PRECISION PLAYBACK CURVES - lifetime encapsulated
precision plug .. in networks, instantly replaceable if equalization curves change.
ULTRA COMPACT, EASY MOUNTING.
Built-in power for Weathers cartridge,
film proiector photoce lls, condenser microphone •• Distinguished satin-gold LUCITE I
front panel. Custom finished
table
cabinets available. Many extras.
INTERELECTRONICS
2432 Grand Concourse
New York 58, New York
16
In proposing the new au'dio triode, Mr.
Markwalter (LETTERS, N ovember ) put his
fin ger on the problem-if a triode is to draw
suffi cient plate current at low plate voltage
it must necessarily have a low mu, and is
therefore hard to drive. On the other hand,
a high-mu triode, easy to slrive, demands
a high-voltage plate supply, though this
latter isn't so difficult these days, using
"ham" type power transfo r mer s and rect ifiers.
Still, he needn't look so far for his
"dream" triode. T ak e a look at the specs
for the 3C33- twin triode, mu of 11, di ssipation 15 watts per side. It fit s his description fa irly well, and the only drawback is
price. For some reason, probably small
demand, this bottle sells for $25, though
some of the surplus dealer s occasionally
have some at about one third of that. D eniand would r educe the price, I'm sure,
and it doesn't look any more difficult to
make than a 6AS7G, for example, except
for the fan cy all-glass mount. Possibly for
audio use this tube could be based like the
6080 and 6082, if that would make for any
economy.
It looks
just the same. . " .
, inter esting,
-.
JO H N S. CARROLL,
I Montague T errace,
Brooklyn 2, N . Y.
AUDIO
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•
DECEMBER, 1954
In every field of endeavor ... manufacturing,
the theatre, concert or contest ...
there is always one standout.
In HI-PI equipment the standout is Pickering ..•
Pictering
pioneer in this field , responsible
for the development and introduction of outstanding
components for highest quality performance;
every product bearing the Pickering name
is engineered to conquer the challenge of
AUdiO
optimum performance ... in their manufacture
the most stringent quality controls are
exercised to assure and maintain the "Ne Plus Ultra"
,Components ...
reputation for products featured by the ~ emblem.
SYNONYMOUS WITH HIGHEST QUALITY
(Design ... 1flflanufactu1I'e ... lPe1l'f01l'1!lt1anCe
It's with good reason that professionals use
Pickering Audio Components ... they know
the values built into Pickering equipment.
INVESTIGATE and you too will use Pickering
components for your HI-PI system. . ..
You'll thrill to new listening experiences ...
'
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you'll have the same high quality performance
as leading FM/ AM good music stations, network
and recording studios ... REMEMBER, leading
record companies use Pickering Components
for quality control:
•
PIC&ERING
and company incorporated.
PICKERING PROFES5iO,NAL AUDIO EQUIPMENT
Oceanside, L.I., New York
. .' . Demonstrated and sold by leading Radio ParIS Dislribu'ors everywhere.
For 'he one nearest you and lor detailed 'i'eratur~i write Dept. A-6.
AUDIO
•
DECEMBER, 1954
19
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AmericanRadioHistory.Com
HAROLD LAWRENCE'"
More Than Meets the Ear
the dumpy and
yet curiously dignified fi gure of Sir
Thomas Beecham lumbered across
the stage of Carnegie Hall toward the
podium for a performance of Lord Berners'
The Tritttnph of N eptulle. The audience
settled back in its seats in anticipation of
some superb music making. H ere was the
unexcelled Philadelphia Orchestra led by
a 'conductor whose very life and personality
were perfectly attuned to the score at hand.
Stroking his goatee, Sir Thomas waited for
the applause to die down, and then began
what was to this writer one of the most
sparkling performances of his career. Near
the conclusion of the work, a surprising
event took place. Ushers suddenly ' were
making a search of stai rways and corridors,
some in the audience took quick glances
down the aisles and under the seats, and
the hall was momentarily filled with -the
buzz of whisperea exclamations. The cause
of this mild excitement was what sounded
like an invasion of a pack of fox hounds in
hot pursuit. The grins on the faces of the
Philadelphians, however, gave them away.
Sir Thomas had instructed his men to bark
(as indicated in the ballet) duripg a certain passage in the score. An ovation
greeted the performers-dogs and all-at
the close of the concert. Everyone seemed
to agree that the Berners piece was the
highlight of the evening.
Ever since his first piano pieces were
published in 1914, Lord Berners (18831950 ) has been tagged by critics and public
alike as a tongue-in-cheek dilettante whose
music is no more nourishing nor lasting
than the nose-tickling bubbles in a cham·
pagne glass. And works like The Trium ph of
N eptulle would seem to support this theory.
Gerald Hugh Ty rwhitt-Wilson (Berners'
family name) was born in Shropshire, educated at E ton, and spent many of his early
years abroad learning French, German, and
Italian in preparation for a diplomatic
career. H is initial musical . studies were
made under a dryasdu st English professor
who thoroughly submerged any love the
young man may have felt for the art. After
a few of these sessions, Bern ers returned
to diplomacy with a pr ofound sigh of r elief.
But shortly before W orld W ar I, he met
two composers who were to revive his
musical instincts: A lfredo Casella and Igor
Stravinsky. Berners' unique gifts were at
once apparent in his early set of piano
pieces, Three Little Flmeral March es
(1914), which Casella introduced in R ome
at the Academy of Santa Cecilia in 1917.
A
BOUT TWO YEARS AGO,
TRIAD
High Fidelity
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~ ho.me music system which will meet true high
fidelity standards must necessarily be composed
of the very finest components - pickups, turn.
tables, amplifiers, speakers, enclosures.
. In .this group of components Triad offers High
Fidelity Amplifier Kits - built by men with a bril·
liant background in producing America's finest
transformers. Engineered to produce maximum
frequency range with minimum distortion these
"do·it·yourself" kits afford obvious eco~omies
over complete units - which permits upgrading
of other components in the system.
Triad High Fidelity Amplifier Kits include all
necessary transformers and chokes, punched sec·
tional aluminum chassis and complete assembly
instructions.
In quality and performance they are fitting com·
panions to the finest sound system components
available today.
HF-3 Kit: Preamplifier. Adequate gain to drive an HF.40
or HF·18 from any commercial pickup or microphone.
D. C. filament supply. Complete record compensation
and new tone control circuits. list Price - $32.80.
HF-12 Kit: 10·watt power amplifier. Replaces HF.lO.
Built·in preamp to accommodate all crystal and mag.
netic cartridges . Complete record compensation and
new tone control circuits. Output impedances 4-8.16
ohms or 125-250-500 ohms. list Prices from - $50.40.
HF-18 Kit: " Williamson" type all·triode amplifier. Full
power output of 16.2 watts for triode operation or 20
watts for pentode operation from 12 to 60.000 cycles.
Frequency response within 0.2 db from 7 to 80 kc.
Output impedances 4·8-16 ohms or 125-250-500 ohms.
list prices from .- $63.65.
HF·40 Kit: Features a full 40·watt amplifier from 20 to
40 ,000 cycles, using regulated screen voltage and fi xed
bias on two 6146 output tubes. Output Impedances
4·8-16 ohms or 125-250-500 ohms. list from - $7~. 35.
This apd a number of other Berners com·
positions are now available on an excellen1
MGM recording performed by Menahem
Pressler. All the familiar Berners elements
are here: satire, parody and acid charm.
But this is not merely the work of an ac·
complished amateur who, in the words oj
one critic, "unable to reach the sublime,
contented himself with the ridiG,Ulous; an
artist who, too insignificant to make a good
portrait painter, fell back on becoming a
cartoonist."
A number of factors have led to the
pigeon-holing of Berners' music in particu·
lar, his extra-musical activities. He did, in
fact, carry his original intention of becom·
ing a diplomat, his first assignment being
that of attache to the British Embassy in
Constantinople. He was an accomplished
painter and a brilliant writer. In addition
to a stimulating autobiography, he wrote
some fantastic novels. Two of the latter
are worth mentioning because they reveal
something of the man's personality. In
R OmG1ICe of a Nose, Berners develops the
theory that, before her historic meeting
with Caesar, Cleopatra had suffered
through a perfectly miserable ad6lescence
due to her repulsively large nose. Her
political enemies capitalized on her de·
formity by waging a campaign of ridicul.
(Continued on paqe 61)
Eric Satie, by Picasso
(Courtesy The Bettmen Archive)
AUDIO
20
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•
DECEMBER, 1954
is the perfected
"long-playing"
magnetic
tape, bringing
you 50 % extra playing time with no compromise in
strength or recording quality.
One reel of "Plus-50" is equal in recording or playback time to 1 Yz reels
of standard tape. More listening per
reel ... less time changing reels. Best
of all, Soundcraft "Plus-50" actually
costs less per foot than quality .acetatebase tapes!
The secret of "Plus-50" lies in its extra thin "Mylar" base (1 mil as compared to 1.5 mils in acetate tapes).
"Mylar," DuPont's Polyester Film, con-
AUDIO
•
tains no plasticizer. It will not cup or
curl. Elongation and shrinkage from
heat, cold and humidity are barely measurable. And it's far stronger than the
thicker acetate ... one 'third as strong
as steel!
- There has been no compromise in the
development of "Plus-50"-a big adva~tage for you! The oxide coating is
constant, full-depth - to maintain correct frequency response, output level,
and bias characteristics. No machine adjustments are needed. "Plus-50" can be
interspliced with other fine auality tapes
without level change . .
See your Soundcraft Dealer for .
"Plus-50" as well as these other famous
Soundcraft Magnetic Recording Tapes:
DECEM'BER, 1954
www.americanradiohistory.com
AmericanRadioHistory.Com
Soundcraft Recording Tape (in the box
with The Red Diamond) the all-purpose
"Standard of the Industry."
Soundcraft Professional Tap& (in the
box with The Blue Diamond) for radio,
TV and recording studios. Splice-free up
to 2400 feet. Standard or professional hubs.
Soundcraft LIFETIM t/> Tape (in the box
with The Yellow Diamond) for priceless
recordings. DuPont "Mylar" base. For
rigorous use ... perfect program timing.
Store it anywhere virtually forever.
Soundcraft Tapes are the world's finest-ll:nd yet they cost no more.
/
FOR EVERY SOUND REASON
REEVES SOUNDCRAFTcORP.'
10 East 52nd St.,
NewYor~
22, N. Y.
I
He's using the telephone
that lends a n extra hand
J
"Sure . . . I' m looking up the figures rig ht nowl" F rom busy executives to clerks, people in business can
wo rk more easily and efficientl y with Bell's new Distant Talking T elephone. Small white rectang le is t he loudspeaker.
For people who want to keep both
hands free when they telephone, Bell
Telep hon e Lab or a tori es en gineers
have devised a new telephone with a
sensitive m icrophone in its base.
To use it, simply press a button. The
microphone picks up your voice and
sends it on its way. Your party's voice
comes to you through a s~all loudspeaker. Both hands are left free.
The volume can be adjusted to suit
yourself. If privacy is needed, you
simply lift the handset; this shuts off '
the microphone and loudspeaker and
you t alk jllst as you would on a regular
telephone.
This new development of Be11 L aboratories increases the number of ways
your local Bell telephone company can
serve in businesses and homes.
Bell Telephone Laboratories
I mproving telephone service for A merica provides careers
fo r creative men in scientifi c and technical fields.
www.americanradiohistory.com
AmericanRadioHistory.Com
Pencil points to microphone in base of new
telephone. Left-hand button control s volume,
center one turns set "o nu and lights up while.
in use. The third is an "off" button.
Evolution of "The ·Horn "
EDWARD V. KETCHAM, JR.';'
The conception, design, and construction of a speaker enclosure consisting of a closet-contained low-frequency horn with a midfrequency horn and two high-frequency sound producers.
T
HE HORN" is a home-built loudspeaker system. It is large in size
and magnificent in performance. It
was conceived as a result of reading
about Albert Kahn's huge home audio
installation publicized as a "Residence
Entertainment Center" by ElectroVoice, Inc. Mr. Kahn is president of this
organization. The "Center" features a
bass ~ection comprised of a large horn
driven by two 18-in. woofers, and occupies one entire end wall of a sizable,
room.
More specifically, "The Horn," truly
an amateur's project, was first considered as a half-size edition of Mr. Kahn's
installation, turned on end and backed
into a rectangular hall closet. As completed (Fig. 1) it became a combination
of Klipsch speaker cavity and horn
throat principles, feeding through an exponential horn, plus design features and
driver components of the Electro-Voice
Patrician. The entire assembly was designed and built to fit existing closet
space and exhaust into one end of the
living room listening area. Technicians
may find faults in its layout, but it performs superbly.
General procedure was as follows. Details of the "Residence Entertainment
Center," the Patrician, and some basic
rules of horn design were obtained. Paul
Klipsch's papers on folded horn principles and the Jensen monograph on
horns were studi ed. The basic idea of a
low-frequency horn with its mouth divided in t wo by a compartment containing associated apparatus was drawn to
rough scale. It became appa rent that it
would be advisable to face the low-ft'equency woofer speaker away from the
li stening area, and fold its associated
horn around two right-angle turns t6
bring the latter's mouth out in the desired direction . This design feature
would provide the longest path and most
gradual taper with in the limits of available space.
Concentrating on this low-frequency
horn, an approximate path length was
establi shed. After several false starts a
list of cross-sectional areas was compiled. The li st itemized the recommended
area of (a) the mask opening in front
of the 18-in. woofer, (b) a pre-throat
chamber, (c) an eight-inch-IDng throat,
and (d) calculated areas at six-inch intervals along the length of the horn. Figures from (d) establ ished an exponentia curve or expansion l:ate to the
* 50 South Bay Ave., Brightwaters, N.
AUDIO
•
Y.
recommended mouth area. Working dimens ions were figu red from (d) by assuming widths as large as closet space
allowed and dividing these into the listed
values, the quotients denoting height or
depth dimensions. The drawing of Fig. 2
details the results of these calculations.
Lest your interes t sag at this point,
the end product is a low-frequency horn
from which pours full, clean, unforced
low-frequency sounds- a tuba player at
an interview trying for his lowest note,
Mr. Cook's organ records, a ,bass viol,
drums-without resonant peaks or "behind'- the-door" muffled effects . First
indications of its performance became
evident upon completion of the basic
structu re and the installation of the 18in . .woofer in its tightly sealed cav ity. A
test was made on the concrete- floor of
the garage workshop using a Cook test
[email protected] and lO-watt amplifier.
The first try ran at moderate volume.
\iVai ting for the test record to run its
course provided anxious moments as
treble tones weakly wandered forth. One
thought was paramo unt. "When will it ·
take hold? Will it take hold?" At about
500 cps the test tone became solidly
effective and then progressed lower and
lower. Positive response was audible
down to 30 cps and apparent response
below that; however, the pickup used
and this layman's ears preclude accurate judgment in this rock-bottom
region. Theoretically "The Horn" functions to 25 cps and the speaker resonates
at 27 cps.
A repeat test at high volume produced
sufficient unadulterated low-frequency
Fig. I. The finished enclosure is mounted in a closet with the divided horn exhausting into
the listening area. Between the two sections is the TV receiver. The upper section will be
covered with a grill similar to that over the lower section.
DECEMBER, 1954
23
www.americanradiohistory.com
AmericanRadioHistory.Com
sound power to be a potential cause of
physical damage in a finished room. Vibrations created a sense of being sur~
rounded by something untouchable.
Small objects moved of their own accord. Others vibrated audibly. Small
wonder that a chance visitor arriving
upon the scene, replete with the odor of
drying paint, accused the writer of nefarious activities relating to the produc·
tion of. illegal beverages I
Construction
The photos of F~gs. 3 and 4 illustrate
construction details. Upper and lower
mouth sections, throat and back are
built separately, then assembled. The
speaker cavity came last. Joints are
glued throughout. After testing at loud
volume strong bracing was added to the
back of the speaker cavity to reduce the
possibility of developing extraneous vibrations. It is believed this can be better
accomplished by building the cavity irregular in shape while maintaining- it~
cuhic content.
Having successfully provided for lowfrequency range, the next stage was the
building of a 200- to 600-cps horn for a
12-in. woofer, as prescribed by the Patrician details. This was patterned directly
from the furnished data except for two
variations . Available width being less
than specified, the height was increased
to maintain prescribed mouth area. The
second change consisted of arranging the
horizontal and vertical axes off center so
as to aim the unit toward the exact center of the listening area at ear height.
Then the upper frequencies. Purchased Partician components were arranged to point at the listening area center point. From 600 to 3Soo cps a
horn-type driver unit operates through
a multicellular horn with 600-cps cutoff.
Two tweeters operate from 3S00 cps up.
One, a horn-type driver operates through
a multicellular horn with IS00-cps cutoff. The other is an 8-in. cone speaker
modified for extreme high-frequency
operation . A four-way elividing- network
A.h ·
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HOll{<
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I
,
,,
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I
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,
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t
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10
SECTION
FAONT
A -A
1
Fig. 2. This drawing gives all the dimisions of the aufhor's version of "The Horn." Some
alterations may have to be made by other constrj'ctors ' to fit· existing spaces.
24
channels source material signals to the
proper drivers.
With the assembly of all component.'
completed, further tests were in order
After preliminaries with the test record.
the writer proceeded to launch units oj
the New York Central Railroad upon "
new route via Cook's "Sounds of OUT
Times" by way of an open garage door
The open mouthed admiration of a four year-old neighbor was wondrous to hI"
hold.
A word now from the voice of expen
ence! No doubt you know of the fe1loVl
who built a boat in his basement and
was unable to get it out. Similarly let it
be understood that a big audio horn
once built . . . has to be installed. In
planning, one must consider not onl)
available area for the installation bUl
also difficulties in reaching that area
"The Horn," while restricted in width
to that of a hall closet, is ceiling hign
and cannot pass through doorways in an
upright position. A five-foot closet depth
and corresponding front-to-back dimension, however, make transportation possible face down. This does not entirel)
conclude the problem as the over-all
diagonal measurement from bottom fron1
to top back momentarily is all important
when raising the assembly to an uprighl
position. In the case of "The Horn" 001'
inch to spare proved sufficient.
Finishing was handled in a novel man ·
ner, as the photos reveal. The wall wa~
~rst torn away exposing the closet in·
stallation area. The unit was backed into
position. Wedges were driven between
the unit and surrounding walls. Lag
bolts through the sides into adjacent
studs made everything "solid as a
house." With "The Horn" finally at it5
destination, panelling was installed
across the entire end of the room on top
of existing plaster. The panel seam~
were spaced so that the wall opening at
the closet measured exactly four board5
wide, as can be seen on Fig. S. An upand-down sliding panel of like material
and similar width was constructed on
concealed slides so that it can be raised
out of the way through the ceiling. A
counterweight simplifies this maneuver .
In passing, the writer admits partial defeat at tRis stage as the panel wa!-divided and hinged across it center mak·
ing a visible steam. The only alternatewas to "raise the roof." The next project
will be to provide push button control of
this panel with an electric motor mee-ha nism.
A sliding drawer or cradle perrnit~
the TV chassis to be serviced; a TV
front panel and a plastic grill cloth pro·
vide finished appearance. Source mate·
rial comes from amplifier, FM tuner ,
and record player in a fireside wooel
closet at the far end of the room.
Other Speakers
In experimenting with "The Horn"
by changing relative volume levels of
the different drivers, the writer has
formed an opinion that may be of general interest. It is that most approaches
to extended low-frequency reproduction
AUDIO
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AmericanRadioHistory.Com
•
DECEMBER, 1954
Fig. 3 (above). Side view of "The Horn" shows some idea of the construction. Fig. 4 (left). This three-quarter view shows placement of the
200-600-cps and lower-frequency horns.
the home indirectly cause poor
,peaker response in what may be termed
upper bass. To substantiate, the bassboost curve of home amplifiers peaks between 50 and 100 cps. Enclosure designs
are available that are remarkably efficient in this range, and when used with
a low crossover network and level controls usually make amplifier bass boost
undesirable. Under such circumstances
the direct-radiator cone speaker employed for midrange reproduction lacks
bass ' boost that it can use to advantage.
Said boost not being present, the overall response curve of the speaker system
droops in the upper bass range. This
droop may lead some to think their lowfrequency units perform better than is
actually the case, due to the relative difference in output volume between the
low and midrange speakers.
The remedy is to employ a separate
upper-bass speaker. Its efficiency must
compare favorably with the extreme
low-frequency unit. Such a device is tile
200-600-cps horn with 12-inch driver
described above as a component of J'The
Horn." It plays a large part in producill
AUDIO
..
ing the wide-range, even response that
is the outstanding characteristic of this
multiple speaker system.
Building and installing ·'The Horn"
was an adventure. Test record tryouts
and lengthy listening sessions have revealed wide-range efficiency most rewarding for the effort expended in its
creation. It utilizes equipment found in
the most elaborate factory assembled
systems and several enthusiastic critics
consider that its performance ranks with
the best professional demonstrations, yet
through home construction many dollars
were saved, and the system was built in.
The writer formerly used a high-priced
coaxial speaker mounted at the location
now occupied by "The Horn. " The
closet served as an infinite baffle and the
same source material equipment was in
use. There is little comparison. Directradiator speakers are not in the same
league with several properly-hom-loaded
drivers.
Yes, it was a satisfying adventure.
Look arou nd, friend ! Have you a workshop? A strategic closet? Ever knocked
down a wall? You have? Well?
Fig. 5. This photo shows how the entire instal·
lotion is covered by the vertically sliding panels
when it is not in use.
25
DECEMBER, 1954
www.americanradiohistory.com
AmericanRadioHistory.Com
at home with
LEWIS C. STONP
Hi-Fi a la Mode'
For thoroughly enjoyable "living with music," why not utilize a tape recorder, radio, records,
TV, and .automatic controls to give you the kind of entertainment you want throughout your
home-equipment that even saves up your favorite programs for you when you aren't home?
URI NG September's closing days, there came to view in'
a national magazine a sequence of full-page color ads
in which a group of manufacturers displayed a common interest in, of all things, the TV room. Each of the four
double spreads came up with suggestions-one for arranging and using comfortable viewing furniture, another on
floor carpeting, another the TV set itself, the next on painting and decorating walls and woodwork-in each case
urging their products on the TV-room-fitted consumer. In
huckster language, the institution of the TV room was
being merchandized by fo ur manufacturers-one for each
of the commodities described- and with apparentl y telling
results. As fo r our hi-fi brethren, they were nowhere 111
evidence. They missed a bet.
•
Someone must surely, and pretty soon, come u,p with as
good a merchandising presentation-exploiting the idea of
the TV ana Hi-Fi room and its fashioning and furnishing.
There you really have a broadly functioning home entertainment center, carrying not only the transitory video
D
* 235
E. 22nd St., New Yark 10,' N. Y.
image, but also the recordable, replayable and repeatable
radio broadcasts with the aid of the TR (tape recorder) on
the audio end of the electronic home entertainment spectrum.
We will then see the merchandising of an environment for
the most shared entertainment spot in the privacy of the
home. With it will go the full panoply of tuners, pre- and
power amplifiers, turntables, changers, speakers, microphones, cartridges, pickup arms, tape recorders, automatic
timers, etc., etc. This dream is not ours to claim, nor are
the huckster ish details of its execution our concet'n at the
moment.
We have, in fact, touched on the hi-fi environment to
some extent in this department, ever since we entereQ on
our agenda (AUDIO - for April 1954) "variations on the
theme of housing the equipment" as one of our areas of
discussion in these pages. The theme comes up time and
again, as we receive communications from more and more
of our readers among whom are hi-fi devotees whose fervent addiction literally compels a full and proper appreciation of the importance of being in earnest about the
place of the hi-fi system in the home.
Study With Hi-Fi
Take, for instance, the system conceived by a reader in
Ch icago and collated by a local firm of audio engineers. It
is fine proof, we think, that "how-to-do-it" is a question
that never fails of ever new answers. For is it not always
a qualified "how to do it, h'ere in my place, for my use.. . ."?
And each answer in the particular can so easily become the
inspiration to anyone for yet another variation on the
same theme. An electronic chain reaction, so to speak. In
figuring out your hi-fi system requirement you establish,
pretty nearly, its housing and environment too. Thus, as
our Chicago reader reveals in his communication, a complete hi-fi system with TV can be contained in a housing
area of 78 vertical square feet and taking less than 15 square
feet of floor area. A thoroughbred system, this, in a planned
environment created within a study, a room measuring 12
by 18 feet, and resulting in appearance like Fig. L
Here is a hi-fi system complex yet flexible; massive, yet
compactly contained; tractable in its operation to the point
of robotism, yet mood-responsively versatile. It is, in short,
a system where ingeniously placed relays have parlayed a
Fig. 1. Music wall takes a modest nine-foot square corner in room
12 by 18 feet, houses compactly a complex of hi- fi equipment, including professional tape recorder. Finish is sandalwood on mahoganyfa ced plywood. Clock at top is independent of audio system. Note
Plexiglass hoods over tape reels and tllrntable. Remote TV tuner is
.
in magazine rack.
AUDIO
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•
DECEMBER, 1954
PICTURE
TUBE
MAIN SPEAKER
JIM LANSING
AM/FM ANT ENNA
0 -0 50
a: t---t-~:---l
SPEAKER
SYSTEM
~----1 "' ~~
ex:
:r: .....
'"
If)
1-----1-----1 ~
~
i:
~
5
JIM LANSING
0 -050
0
~
SPEAKER
SYSTEM
AMPEX OUTPUT JACK
ON PANEL FOR
DIRECT DUBBING
HIGH LEVEL INPUT
JIM L ANSING
0 - 050
SPEAKER
SYSTEM
L-___
A. C. TO ALL EQUIPMENT
E XCEPT T V
Fig. 2. Block diagram ind icates a fullsome handlin g of one fa mily's high-fidelity and TV requi rements. Installa t ion fe atures relays for fully auto matic operation, with individua l switch ing at each speaker, maste r con trol in master bedroom.
music-wan COl1struction-a pleasingly styled adjunct of the
home environment-into an eloquent return on the (not
inconsiderable) investment. Our waIl's opacity is only optically so, for it offers no barriers to the inner ear. You can
grant, can you not, that this kind of wall with its very
special hi-fi equipment, as thoroughbred as any in the field,
is graced with the capacity to loosen tendons tensed from
the day's desk and briefcase concerns, when it translates
electronic impulse into music or recitative that can open
wide the casements of the soul?
All the more reason, then, so to avail yourself of the
best in electronic devices that the playback or program
transmission can be effortless, spontaneous, akin in . its
presence and responsiveness to anybody's dreams of wish
fu lfiIlment. To accomplish this remotely controIled apparatus
honors directly, automatically and with the greatest of ease
any draft you may present upon the program-banks which
you have laid in to the enrichment of your archives of recorded sound on tape. The tape recorder is the functioning
core of the whole scheme of this undertaking.
Our communication implies that broadcast music is reeled
in by automatic relays, tape recorded through FM tuner at
.a preset time and later,' at will, channelled through to any
one, or combinations, or all of the nine speakers of the
house. Each of these can be independently "included" in or
out by direct switching. And, by low voltage relay, the
entire array of equipment may be brought to full voice, or
silenced, from the master bedroom.
In this room the programs sifted by a Fisher 50-C
preamp from either tape, radio, phonograph, turntable or
microphone are heard through a Jim Lansing three-unit
D-050 speaker system. This is identical with the main
speaker components contained in the music wall aggregation in the . study. A like speaker system is in the living
room. The entire system is shown in block form in Fig. 2.
2 0 ,000 cps with Bath
Effortlessly, high fidelity sound is everywhere. With the
ease of tapping water from the house lines for a warm bath
is program or playback s9und piped to both bathrooms
AUDIO
•
through wall-mounted Jensen P8RX speakers. \ '\There body
lies in its bubble bath, there also can spirit be soothed or
. stimulated. And when relaxe.d -dry on. bed or couch, the
program is stilI heard with full presence, yet mild volume.
An automatic relay operates to br ing. a continuity of music
from one source or another. Ordinarily, when the tape reel
runs out its full hour, the Ampex stops automatically as the
tape tensioner arm swings free. It is then that a relay comes
to life, switches the number one input of the preamplifier to
the output of the tuner (both are of F isher pedig.ree) and,
again automaticalIy, the radio serves up its preset dish of
programming, with hardly a noticeable pause as one instrument gives way to the other.
In its robotish phases, this system can provide complete
program continuity. But this is no Frankenstein monster,
imposing itself relentlessly and uncontroJIably upon our
natural inclination and need for quiet. That state you achieve
with a manual switch, located at each of the extension speakers, wherever they may be in the apartment, including the
kitchen. The system is. designed to inscribe a preselected
radio program onto the tape recorder in the owner's absence, by means of a 24-hour timer which is set into the
apron of the Ampex just below the tape transport plate, as
seen in Fig. 3.
An ingredient had to be added, according to system de. signer Irving Rose, in the way of an automatic relay to
close the start switch momentarily when the time clock
turns the Ampex on for a preset program tal{e off. Since
this machine has only the one input available, an input
switch was added to provide choice between microphone
or high level line feeds, or both.
Life with Hi-Fi
This hi-fi system is lived with daily by a well known
manufacturer in the electronic industry and his family. The
broadcast station log does not always accommodate itself
to their listening or leisure habits. So the clock-and-relax
mechanism records daily favorite news or musical programs for later listening. EspeciiLlly on Sunday, while the
family is visiting or golfing, do they appreciate their robot
DECEMBER, 1954
27
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Fig. 3. Audio equipment grouped for convenient manual operation, also works completely automatically. Note 24-hour program timer belo...
tape reel plate and controlling toggle switches alongside. Amplifiers feeding main and extension speaker systems are housed below 24-inch pic·
ture tube; also relay chassis and separate amplifier for TV sound. Main speaker system is behind screen over picture tube. Tuner and preamp
are placed between tape recorder and turntable. with record changer on slide-out below.
. hi-fi system. No one is home, the apartment is still. Under
orders from the clock, the automatic switches, the relays,
the radio, and the tape recorder all come to life, silently and
diligently to imprint the desired program on tape for later
playback when the family is home to hear it.
Sometimes phonograph records~p articul ar1y hard-tofind collector's items which may occasionally be borrowedare mounted on the Rek-O-Kut turntable with its complement of Gray viscous-damped tone arm and Fairchild pickup
cartridge, and played into the tape recorder. Both 70 and
3:J1i inches per second speeds are available with the Ampex
tape machine. The frequency response at the lower speed
is reported to be ± 2 db at SO to 7,500 cps. Adequate for recording, say, jazz and folk music, which is exactly
what this family does when tape recording popular music.
By the same token, the classical record numbers and programs get the 70 ips tape play treatment. At this speed, the
response is said to be ± 2 db from 40 to 10,000 cps, and ± 4 db
from 30 to 15,000 cps. This last rate of frequency respqnse
is hardly distinguishable (by the ear, though instrumentmeasurable ) from the ± 2 db produced at the doubled speed
of 15 ips for the identical fr equency response. Our knowledgeable electronic manufacturer is quite aware also that
the more moderate tape speeds mean one full hour per side
of tape reel (2400 ft.) for the 70 ips, while the 3:J1i ips
rate keeps each s irle of th e tape reel going fo r a full two
hours. Economy!
With the tape recordings frU11l discs usual)y go comment~
identifying the composer , the selection to be played, and so
on. These are spoken into a Shure Concert-Line Gradient'
"300" micophone. For straight disc playback a VM Triomatic change!- is used, fitted with a Shure Twin-Lever
hi-fi Ceramic Cartridge.
Obviously, the rack mounting units of the Ampex 350
have been used in thi s undertaking. They are quite neatly
mounted in the wall housing, in company wi th the other
components of equal quality. For ready access when that
becomes necessary, all the components are mounted on
separate slide-out assemblies. The tape transport swings up
on two 3-inch loose-pin hinges mounted at the back. Over
it a Plexiglass cover, domed to clear the equipment, is
held up by a sliding bracket, closes down protectively
with a lig ht hand pressure. (This is one of the very few
pa rts of the system not a utomatic). A similar covering
serves to g ive protection (with full visibility, in both instances) to the tumtable and its precious pickup. The control pan el of the Am pex machine tilts up when the outer
panel of the cabin et is pulled out (flour-bin fashion) and
this too, can be opened up to reveal its electronic insides. If
not always for servicing, then for the ego-satisfying curiosity of your env ious fri ends as they pop their eyes upon
their well-ordered complexity.
28
AUDIO
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•
DECEMBER, 1954
For' those able tool-handlers to whom no installation is
without challenge, including their own, we include in F i g. 4
some dimension sketches of cabinetry. Basically, a shelf
job it is, and who is it hasn't done one? Does your ambition
tor the best grace (alas!) a high reluctance pocket I book,
then will you take the hi-fi path on a lower road. But without compromise. Better to proceed with the carpentering of
the shelves yourself, than to shelve the idea wholly. Better to
proceed monogamously at first, than take on a whole harem in
one avaricious swoop. Electronically speaking, that is. There
are, in this communication, enough components described
and placed, and the ways they are lived with reported. Sufficient, is it not, to sharpen your appreciation that thorobred
fitments are in a class by themselves?
There need be no mystery of choice. This is no "lady or
the tiger" deal. You can saw your wood to cut your costs.
You could, to begin with, erect a half-wall, for instance.
Most of the working thorobreds are "stabled" in the lower
parts of the music wall, anyway. Draw on these components,
or their like (there's today plenty of the thorobred breed in
hi-fi equipment available) for your first steps on the hiroad to hi-fi. And verily, your last (steps) shall be as the
first.
Bat perhaps we are spending your money too fast. In
your ambition for the absolute in hi-fi, do not, then, minimize the virtues of the median. There is fun in the pilgrimage to progress, say, from first choice of what will later be:,
your second (or auxiliary) speaker-when you have made,
that is, final choice of your "first" or main speaker. And if
it is preset on-off programming or listening you want right •
off, why then a speaker system like the "University" Companion fitted with a Sessions electric clock, could serve. And
so on, as a beginning. All you need to do is to decide what
facilities you want-practically any type of service can be
provided, so just name it and roll up your sleev.es.
Details of the System
Beginning with the "receiving centers," of speakers there
<ire nine, each in a different room. The main speaker, in the
study, is the three-unit Jim Lansing D-050 system, with
two IS-inch low-frequency units and one high-frequency
driver equipped with a horn and Koustical lens assembly.
These work from a I200-cps dividing network. Two more
systems of the same type are used, one in the master bedroom and one in the living room.
Wall-mounted in the dining room and kitchen are J ensen
jo--
H-222 coaxial speakers, Jensen P8RX 8-'inch spi ilkers in
both bathrooms, and two Jensen 12RX speakers in the
remaining bedrooms.
. Amplifiers : The main speaker system is fed by a McIntosh A-116 30-watt amplifier. A Fisher 50A 50-watt
amplifier serves the extensio!J. speaker line.
Tuner is the Fisher 50-R, AM-FM.
Preamplifier is Fisher Model 50CH. This is the control
center of the system, providing selection of program for
tape, radio, television, phonograph changer, turntable, or
microphone. Sound from video has a separate 10-watt
Craftsmen C450 amplifier.
Microphone is the Shure Model 300 Concert-Line
Gradient1 .
Tape Recorder is 2-speed Ampex Model 350, lO-inch
reels.
Record turntable is Rek-O-Kut T12H, three-speed, with
Gray 108-B viscous damped tone arm and Fairchild 215-A
pickup cartridge.
Automatic changer is VM Triomatic, with Shure "Twin
Lever" hi-fi Ceramic Cartridge.
Program timer clock, Automatic Electric Company, Chi,.
cago ; the relay system was custom designed.
Cabinetry Details
The music-wall is made of ~ - and yg-in. lumber-core
architectural mahogany-faced plywood. The thicker sections
are used for support areas and end pieces. Over-all dimensions : 9'-0" high by 8'-8" wi<;le. Bottom compartments are
200 " deep. The top portion is stepped baek to make a depth
of 16 inches. The finish is in warm "Sandalwood."
All cabinet doors, including the clock-mounted panels in
upper section, are operated by "Tutch-Latch," including
the flour-bin tape recorder door, which is also fitted with a
spr ing-loaded assist to move the mass easily.
H eat 'g iven off by the equipment is dissipated by flue action created behind the units, as shown in Fig. Cold air is
brought in through toe kick at the floor, vented through an
opening in the upper section of the cabinet.
Note: For a check list of woodworking and other tools,
do-it-yoUl"selfers are referred to "at home with Audio'.' in
AUDIO for April 1954.
Credits
Installation by Voice and Vision; Inc., Chicago. Designed
by Irving W. Rose, through whose courtesy this undertaking
is reported here. Photographs by Idaka, Chicago.
- - - - 8 ' 8" -------~
SPEAKER
SYSTEM
HOT AIR
EXHAUST
TAPE RECORDER
24 " TELEVISION
AM / FM RADIO
TUNER
It
~
N
SECTION THRU TELEVISION
AND SPEAKERS
SECTION THRU ' TUNER
AND RECORD PLAYER
FRONT
ELEVATION
Fig. 4. Relays put the entire audio system on notice for immediate or deferred operation. For comments on switches and reJars see page 77 in
The 2nd Audio Anthology.
AUDIO
•
29
DECEMBER, 1954
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Techniques of Microphone
Calibration
ALEXIS BADMAIEFF*
A discussion of the problems involved in the testing of microphones, together
with a description of
th~
equipment required and a comparison of rating systems.
(d) Standard test loudspeaker
(e) Oscillator with its necessary
amplifiers
(f) Standard ref~rence- mrcrophQI1e
(g) Measuring voltmeter
(h) Automatic sound-level recorder.
If such equipment is not available, conCl-ete and reliable calibration is not possible. Some published curves on microphones seem to be exceptionally good;
however, when those microphones are
re-evaluated with the test equipment
described, it is found that their frequency response curves do not compare
with published data. Quite obviously,
either the measurement equipment used
was at fault or some of it was omitted.
The tool that is most susceptible to
faulty operation is the anechoic chamber.
It can be either too small or insufficiently absorbent, which results in standing waves being formed, in which case
almost any response can be measured
erroneously by merely shifting the
microphone from one place to a nother.
A piston phone is an acoustical standard. It consists of a small chamber in
which a piston-driven by a husky loudspeaker driver mechanism-pumps air
in and out. By adjusting the stroke of
the piston when the cavity and all
other dimensions are known, it is simple
to calculate the amount of sound pressure built up within the cavity where
the microphone is placed. The pi5tonphone is a primary standard and it can
be used over a great dynamic range.
Its limiting factor is the ability of a
microscope to measure the excursion
of the piston. The typical pistonphone
shown in Fig . 1 represents the standard
against which all secondary standards
are calibrated.
The next most important tool in
acoustical measurements is the anechoic
chan1ber, Fig. 2. As its name implies, it
is a room wherein no echoes can occur.
Such a room is usually built large
enough to permit entry for placement
of microphones and contains a known
sound source. All inne·r surfaces are
lined with heavy wedges of soft Fiberglas, such as the Owens Corning OC4.
Since reflections from these surfaces
can occur if the damping material's
thickness is less than .0 the wave
length of the frequencies measured within that room, the thickness ·should be at
least two feet. Such a room, then, would
Fig. 1. The piston phone-the primary acoustical
be completely anechoic from about 250
standard.
EARLY DAYS of sound
levels which the microphone translates
transmission, microphone measure- without interference from extraneous
ment consisted .<1n1y Qf. evaluating __ or~unwanted ._s.ounds. Measure!11ents ~f
thiough a loudspeaker or earphones the dire~tivi~y represent .an. essent.lal 'sp-eCImicrophone's apility to reproduce underficatlOn 111 such s~eclahzed ~lcrophone
standable sounds and judge the departypes as the cardlOl~. T~e ratIO ~et",:,ee?
ture from the original. Such things as
h'o~t and back! which IS the dlscnmlarticulation and excessive distortion
nation figure, IS measured and can be
f
d
t
represented on a polar chart or ex. d d b' r · ·
were JU ge
y ISlemng o~ a equa e pressed by a group of curves. These
performance. ~resent day mlcr~phones curves generally will show the differare preCisIOn. 111struments. Dunng .the ence between the front and back pickup
years. of their develo~ment and. time output of the microphone over its en~pent 111 research to achlev.e th~ ultimate
tire useable frequency range. The front
Ir: sound transducers, cahbratlqn techresponse should, of course, be flat to
I11ques also had to be refil~ed because provide a well balanced reproduction.
th?se techmques are the baSIS of evalu- The rear response, even though it is
at !On of a product offered to the user.
attenuated by the amount of the · disMicrophones that are used for broad- crimination ~gure, should likewise be
casting and recording on such media as reasonably flat. If it is not and some
discs, tape, and film, must have an ex- peaks appear in its response, annoying
tremely wide frequency range to !:rans- acoustical feedback conditions will exist
duce sounds over the entire range of at those points if the micropho~le is used
frequencies to which the human ear is for sound reinforcement.
receptive. That frequency range is at
least from 30 to 15,000 cps, having a Measuring Equipment
logarithmic center reference frequency
Much expensive and very special apof about 800 cps, at which point the paratus is reql:1ired to measure and calieffective loudness is determined. To brate microphones properly. Some of
avoid the distortion of the highly com- the essential apparatus needed are :
plex wave forms found in speech and a
(a) Primary acoustical standard
groups of instruments, the frequency
(b) Anechoic chamber
response variation over the wide range
(c) Plane-wave tube
must be held to narrow limits. The
ability of a microphone to fulfill this
requisite must be measured against a
primary or secondary standard. The
departure from this ideal response determines the quality of that instrument.
Frequency response of a microphone is
probably its most impOl-tant specification because not only its range, but
particularly the smoothness, is of paramc.unt importance.
Waveform distortions generated by
the microphone under any conditions
must be held to a minimum and measured to establish its dynamic range. The
low limit of the dynamic l-ange is established by measurements of the electrical output when no sound is present to
determine the noise generated. This
means that the magnitude of the electr ical output between· the point of distortion and the point of noise determines
the dynamic range which is also the
t-_
ratio of minimum to maximum sound
URING THE
D
--I
*Altec Lallsillg Corp., 9356 Sallta lV]onica Blvd., Beverly Hills, Calif.
AUDIO
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•
DECEMBER, 1954
cps to the limit of the high-frequency
range. Since the floor is absorbent to
sound, an acoustically transparent floor
of interlaced wire netting is suspended
in the lower half of the chamber to permit a person to enter. The door is also
padded to absorb sound .
Since the anechoic chamber is used
only for frequencies above 250 cps, the
plane-wave tube fills that gap for measurements below and to the low limit
of the acoustical range. Figure 3 shows
a plane-wave tube. It consists of a
wooden pipe, 15 in. jn diameter and
about 18 ft. long. The sound source is
at one end of it, and the other end is
damped by several stages of felt. This
tube is used to measure frequencies
from 20 cps to approximately 300 cps.
The microphone to be measured " is
placed in the linear center of the ' tube
where it receives sound pressures emanating from the source, but all echoes
are compl etely absorbed by the acoustical filter in its opposite end.
The next tool is the sound source. The
sound source usually consists of a specially designed speaker having a very
smooth response and able to radiate all
frequencies . to which the human ear is
sensitive. Our test loudspeaker consists
of two drivers. The low-frequency driver
is a IS-in. cone especially treated for a
very smooth response. The high-frequency driver, which is an open diaphragm type, radiates all frequencies
from 1,000 to 22,000 cycles. Instead of
using crossover networks, a mechanical
crossover is used which is in the form
of a multiple switch that switches the
electrical energy from one driver to the"
other. This osci llator and its switching
element are shown in Fig . 4.
Standard Microphone
A standard calibrated microphone is
used to evaluate response runs in the
aneeh0ic chamber or the plane wave
tub~ in respect to the sound source. This
radiation, as measured by a standard microphone such as the Western Electric
Type 640AA, is used to compare the
response of a microph~ne tested under
identical conditions. Having two re-
AUDIO
•
Fig. 2 (right). The
a n echoic chamber.
The fiberglas wedges
on door are shown
uncovered. Fig. 3
(above). The 'plane
wave tube with its
associated equipment.
1
j
sponse curves, one of which is standard,
it is simple to convert the response of
·the microphone under test to a free
fi('!ld response when the performance and
errors of th e standard microphone are
known. It is necessary, of course, that
the calibration 6f' the standard microphone be maintained r'igidly and car~­
fully, and it should be checked by a
qualified laboratory at least twice a year.
The output of either the standard microphone or the microphone under test
is electrically connected to an accurate
vacuum tube voltmeter that is capable
of responding to all frequenc ies in the
audio spectrum without di scrimination.
The output of the voltmeter actuates an
automatic sound-level recorder, Fig. 5,
that plots a trace on a strip of paper by
a pen that is driven by a servomechanism that has been previously calibrated
to follow a logarithmic travel. In this
case, the pen traces db vs. frequency.
When frequency measurements are
made, the microphone can be calibrated
at either parallel or perpendicular incidence to its normal axis. If, for instance,
one would measure a microphone such
as the Altec 2lC having a diphragm approximately 0.6 in. in diameter, the
sound arriving at a parallel incidence to
its normal axis would follow the frequency characteristic of that microphone,
except where the wave length begins to
equal the diameter of the diaphragm. At
that point, some cancellatio!l takes place,
resulting in the attenuation of the highfrequency response. In perpendicular incidence, however, this does not happen
because the diaphragm's sensitive axis
DECEMBER, 1954
is pointing directly at the loudspeaker
source so that the pressure wave strikes
all parts of the diaphragm at the same
time. Normally all calibrations are meas··
ured in parallel incidence because that
is the normal way a microphone is used.
In actual practice, however, parallel incid(mce is often disregarded and the
microphone is "talked to" into its front.
The result in this case would be a more
pronounced extreme high-frequency response. Examples of the parallel inci dence and perpendicular incidence are
Fig. 4. The synchronized oscillator showing the
crossover and limit switches on its dial. The
verticol shoft synchronizes the oscillator with
the pen recorder.
31
www.americanradiohistory.com
AmericanRadioHistory.Com
shown in Fig . 6, which is the free field
response of the Altec 21C microphone.
The exception, however, is in the case
of the- ribbon and cardioid microphones
where their perpendicular axis is normal.
When testing cardioid microphones,
one of the most important measurements
is the difference in amplitude between
the front of the microphone and the
rear. This measurement shows the ability of the microphone to discriminate
between the sounds received from its
front and rear. In certain cases and for
certain uses, discrimination might be
even more important than the frequency
response. Sometimes unusually good
claims are published that show a superior discrimination characteristic of a
cardioid microphone. However, when
such specifications are re-evaluated in a
well constructed anechoic chamber, those
claims are not substantiated. An example of this is shown in Fig. 7, where
the Altec 6i'OA car dioid microphone is
compared to t.w o other microphones of
similar type. These tests were conducted
impartially and automatically where no
human factor entered into the picture.
As is readily seen, the discrimination of
the competitive microphones is excellent
at several points of the spectrum, but
lacking in others. As mentioned before,
this condition will give rise to acoustical
feedback that will occur at frequencies
where the peaks of the back response
occur. A more elaborate form of evaluating the cardioid pattern of the microphone is by the use of a polar chart,
whereby the amplitude of a constant
sound pressure is plotted on a polar axis
as it is transmitted by the microphone.
When the microphone is rotated along
its vertical axis, the shape of that polar
pattern represents a heart-shaped figure
and shows the ability of the microphone
to discriminate loudness vs. its rotation.
This pattern is evaluated by comparing
it to an ideal cardioid shape.
Sound Source
When conducting frequency response
measurements, the standard loudspeaker
source is adjusted to radiate a known
sound pressure level in the mid-dynamic
range of the average sounds encountered
for which the microphone is designed.
Usually a sound pressure level of a1;>out
90 db above a reference of .0002 dynes
/cm2 is used for all frequency-response
and discrimination measurements. Since
Fig. 5. The recorder automatically records frequency response on a calibrated chart. The
recording pen is servo-driven.
the anechoic chamber absorbs the energy
of all frequencies above 300 cps, the radiation from the loudspeaker source obeys
the inverse-square law. This means that
if the distance between the source and
the microphone is increased by two, the
sound power level at that point is diminished by a factor of four. If, however, the loudspeaker source has a horn
attached to any of its driver units, such
an inverse square law is not followed
due to the beaming effect that the horn
produces. This is the reason why standard loudspeaker sources are usually
made of the open diaphragm type.
Microphones that are used for average purposes-such as music, speech,
sound effects, and other sound sources
that are encountered during recording
fo r enterta inment-have a dynamic
range fitted for that range of loudness .
Test microphones, however, sometimes
are designed to handle much louder
sound levels. An example of an extremely loud noise source to be measured is the jet of our modern fighter
airplanes. T o analyze such noise, the
microphone is placed within a few feet
of the exhaust of the jet engine. A normal microphone would be damaged from
the excessive sound pressures. The
Altec Lansing 21BR microphone was
designed to receive tremendous pressures such as explosions, jets, and other
high-level sound sources. The 21BR
type microphone has a very thick glass
diaphragm designed to be stiff enough
so as not to distort the original wave
form at sound pressures that exceed
220 db. In measuring such a microphone,
loud sound sources are required which
ALTEC LANSlNG21CMICROPHONE
RlRALLEL INCIDENCE
~::I;
~~ -40
---- --, - -- - PERPENDICULAR INCIDENCE
S!~
." ,.z
~~ " 4~
... 0
6ffi
.....
-50
5~
~g -5
.~
---
-
~
,,
\
\
0-
....
ffi~
00
20
100
1000
FREQUENCY: CYCLES PER SECOND
10.000
20.000
Fig. 6. Frequency response of a miniature condensei' microphone for perpendicular and parallel
incidence.
are beyond the scope of a test loudspeaker. The calibrated pistonphone,
which is capable of producing great
sound pressures within its small chamber, is used in this case.
When microphones are over-driven ,
they usually distort the wave form of
the orig inal pressure wave that actuates its diaph ragm. Distortion can be
measured by several well known means,
one of which is the analysis of the resultant wave shape vs. the original wave
shape. Such analysis can be achieved
by the examination of the wave shape
by means of a cathode ray oscilloscope.
Also, special instruments that measure
total harmonic distortion and intermodulation are used. These measurements are made in a standard way that
is familiar in the measurements of amplifi ers but taking into account the distortion of the test amplifi ers being used.
One of the ratings for sensitivity calibration of microphones is the ratio of
the sound pressure level to the electrical
output of the microphone. The electrical
output, however, depends on the impedance of the microphone. The rating,
since it incorporates the impedance,
must be computed on a power basis. The
almost universal rating for this sensitivity is decibels referred to one milliwatt of electrical power. The sound
pressure level, also in decibels, is referred to an arbitrary standard of
.0002 dynes/cm 2 •
Sensitivity Ratings
Unfortunately, the sensitivities of microphones are sometimes specified in
different systems. These systems are
based on either open circuit voltage or
power response or the RETMA sensitivity rating. The formulas for each respective system are as follows:
Open circuit voltage sensitivity in db :
E
S . =20 log p
where E = open circuit voltage
P = sound pressure in db (ref: I
microbar)
Open circuit power sensitivity in dbm:
S w=Se-l0 log R+44
where R = nominal impedance
RETMA sensitivity rating in dbm:
_ GlIl.=Se-l0 log R c-50
where R c = nominal impedance (center
value)
The open circuit output voltage of the
microphone S e is in decibels and is referred to one volt/ microbar (which is
1 dyne/ cm 2 ) . The power response S u
is also in decibels and is referred to 1
milliwatt for 10 microbars of sound
pressure level.
Sensitivity rating established by
RETMA is the available power in decibels to a reference of 1 milliwatt for
.0002 dynes / cm 2 • In short, the sensitivity rating is the voltage or power output referred to the sound pressure level
in dynes / cm 2 • Whichever system is used,
whether it is dynes, bars, or microbars,
the rating is still the same provided, of
course, it is stated whether or not that
(C on;tim~ed on page 60)
AUDIO
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•
DECEMBER, 1954
The Juke Box
Goes
Hi-Fi
C. C. McPROUD
Combining good amplifier design, a two-way speaker
system with both units compression horn loaded, and
-an excellent phonograph mechanism, the new AM I
Model F coin-operated music machines bring highfidelity sound into public places.
Fig. I. AMI Incorporated's new high-fidelity Model F juke-box.
HE WORD "JUKE-BOX" as an adjective
takes on a new meaning. Long used
by audio engineers to describe boomy
bass, insufficient treble, and high distortion, the term has been understood by
everyone. But the newest instrument
just introduced by AMI Incorporated
bears a much closer resemblance to a
high-quality home music system than to
the jake boxes of the past, and its electrical and acoustic characteristics are
well worth study by anyone interested
in high-quality sound reproduction. For
in this instrument are incorporated features which may well find their way
into home-type equipment.
The new AMI juke boxes are available in three record handling capacities,
but all ~hree utilize the same loudspeaker
system, the same amplifier, and the same
c()in collection equipment. Model F-40
plays 40 selections from lO-in. 78-r.p.m.
records, and models F-80 and F-120
play 80 and 120 selections respectively
from 4$'s. All three use similar record '
handling machinery, differing only in
size and accommodation. Figure 1 shows
the external appearance of the F -120
model.
Several of the physical features of
these instruments are notable. One of
the important conveniences of Model F
is the accessibility to all of the working
parts from the front so it is never
necessary to move the instrument away
from the wall to service it. The coin
collection equipment, the amplifier, and
the selection control mechanisms may be
reached by removing the bottom front
of the cabinet, while the front and side
glas!, doors may be opened to service the
T
AUDIO
•
pltUllU mechanism or to change reconls
and title strips. All interior lighting
may also be reached from the front of
the instrument.
The cabinets are functional in design
and free from dust-collecting "gingerbread." A new "Miracle Finish" can be
wiped clean with a damp cloth, and is
available in eight smart new attentiongetting colors. Trim is either extruded
polished aluminum or heavy die castings, chrome plated over copper and
nickel, and will remain bright and attractive over long periods in any location.
Heavy legs serve two purposes-they
hold the cabinet up from the floor, thus
allowing sound from the low-frequency
speaker to be distributed throughout the
room, and they hide the casters which
make it easy to move the instrument
when necessary for cleaning. The casters
are designed to permit easy leveling,
simply by placing one or more flat
washers on the shank to raise any qf the
four corners as required.
Speaker System
To the audio minded reader, the
"Sonoramic" loudspeaker system em' ployed in the Model F will be of considerable interest. It is a two-way system, crossing over at 500 cps, and
consisting of a 12-in. cone mounted ' at
the throat of a folded horn 50 in. long,
and with the back in a completely enclosed rear loading chamber. Figlwe 2
is a phantom view showing the arrangement of the speaker and the folded horn.
which is located in the lower compartment back of the heart of the instrument
-the coin collecting mechanism. Low
frequencies are radiated from the mouth
of the horn at the bottom of the cabinet,
and take further advantage of the location against the wall to increase effective low-frequency output. The highfrequency speaker is also compression
horn loaded, using a molded flat horn
located at the top of the cabinet where
it can radiate the sound above adjacent
tables or booths. The horn is formed of
thermosetting plastic, the two halves being held together firmly while they are
cemented. This construction eliminates
resonance, and provides a lightweight
structure which is easily mounted in
the top of the cabinet. Figl~re 3 shows
the construction of the high-frequency
horn, with the driver unit at the throat.
The two speakers are fed from the
outputs of a constant-resistance dividing network with a crossover frequency
of 500 cps. The increased efficiency of
the horn-loaded low-frequency , unit,
driven by the 22-watt amplifier, gives
a sound output comparable to that from
a 50-watt amplifier with conventional
speakers.
Technically, th e dividing network
comprises two 5~mh inductances and
two 17-!J.f capacitors connected in a
conventional parallel circuit, as shown
in the insert in Fig. 4. The high-frequency output is padded down with a
resistor network to balance the efficiences of the two units.
The Amplifier
The amplifier, shown pictorially in
Fig. 5, and schematically in Fig. 4, em-
' 33
DECEMBER, 1954
,
-
www.americanradiohistory.com
AmericanRadioHistory.Com
NEW
888VARIABLE-o*CARDIDID
OUTPERFORMS ALL OTHERS
New E-V VARIABLE-D* Acoustic Principle
Provides High Front-to-Back Discrimination
Plus Wide-Range Response, without Proximity Effect
-in a small, Light Weight Dynamic Microphone
that is Extremely Rugged and Versatile
Here, for the first time, is a completely new cardioid microphone
that meets the exacting requirements of present-day telecasting and
broadcastinK. :. a microphone that readily solves the many vexing
problems of daily operation.
Designed in cooperati o n with network engineers, the E-V "666"
combines the ruggedness of a single dynamic element with a new
acoustic principle that assures smooth, extended wide-range response
... and high, uniform discrimination against sound impinging on
the back hemisphere ... with virtually no proximity effect.
The new E-V "666" is especially useful in eliminating pick-up of
ambient noise, unwanted reverberation, and movement of equipment.
Closely matches existing high quality" pressure microphones, such as
the famous E-V "655", and thus permits easy fading from one
microphone to another.
*PRINCIPLE OF OPERATION
Exclusive E· V VARIABLE·D (for variable dis lance ) provides Ihree back
sound enlrances al differenl fixed
dislances . These enlrances each
possesses a phasing ne"lwork which
operales wilh Ihe olher enlrances
10 provide effective fran I-la-back
spacing which varies inversely wilh
frequen"cy . As a resull , optimum
fronl-Io-back discrimination i s
oblained al all frequencies.
*E-V Pat. Pend.
\1
AUDIO
34
-
\
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AmericanRadioHistory.Com
VERSATILE DESK OR TABLE USE
Model 420 stable desk mount and
clamp permits easy use for quiz
shows or fixed position emceeing.
Microphone simply slides out of
oramp for other use in hand, on
stand or boom.
•
DECEMBER, 1954
DYNAMIC
FOR TV and Be
¢
~
ST~ND
IDEAL FOR BOOM WORK
EASY
Small size, light weight, high resistance to shock, and consistent
performance greatly simplify boom
or fish-pole operation . . . allow fast
pans on boom shots, without worry
about mike shadows. Unique E-V
Model 366 Boom Shock Mount is
optional (extra).
Spring-type , cushioned-slide, studclamp permits instant stand mounting or removal (without marring
surfacel. Smooth swivel allows
proper placement and firmly holds
microphone in desired position.
THESE E-V FEATUR'E S MAKE THE BIG DIFFERENCE
Frequency Response: Uniform response 3015,000 cps . Individua l laboratory control
insures conformity to the highest fidelity
standards.
Polar Pattern: Average front-to-back discrimination 24 db.
Power Rating: Output level -57 db . Provides
excellent signal-to-thermal noise ratio.
Magnet Structure: Alnico V and Armco. magnetic iron. Provides flux density and signal
sensitivity previously found only in microphone heads many times the size of the "666".
Impedance Adjustment: Supplied wired for
50 ohms. Can readily be changed to 150 or
250 ohms on terminal board inside case.
Acoustalloy Diaphragm: Exclusive E-V formulation provides the proper elasticity to complement the acoustical requirements of the
"666". Promotes smooth, wide range
response . Practically indestructible under all
types of operating conditions.
Blast Filter: Acoustical sc ree n protector minimizes wind and breath blasts, and traps iron
filings.
Microphone Case: Made of aluminum and finished in durable TV gray . 7X" long x 1X"
diam. Weighs only 11 ozs. Uses detachab le
clamp-on stand adapter for %"-27 or X" pipe
thread. Swivel provid'es for tilt up to 90·.
Cable and Connector: Comes with 20 feet of
2-conductor broadcast-type cable, and Cannon UA-3-11 conne,ctor on microphone end.
OPERATION
Try the E-Y "666" Now
Prove to yourself the superiority of
the "666". No obligation. Normal
trade discount applies.
Model 666 Microphone .••••. List $245
Includes Model 300 Stand Coupler_
Model 366 Boom Shock Mount. List $40
For easy attachment to standard
booms. Weighs only 6 ozs. Has adjust, able rubber band shock absorbers.
Model 300 Stand Coupler ••••• List $10
Model 420 Desk Stand •••••••. List $20
Heavy cast base finished in matching
TV gray. With microphone clamp.
Available at Authorized
£-V Distributors
Write for Technical Data
Sheet No. 39
ELECTRO.VOIC~t INC. • BUCHANAN, MICHI'G AN
Export: 13 East 40th'"St., New York 16, U.S.A. Cables: Arlab
AUDIO
•
DECE~BER, 1954
35
www.americanradiohistory.com
AmericanRadioHistory.Com
Fig. 2 (left). Phantom view of the folded horn for the compression-loaded low-frequency
speaker. This horn is lo~ated in the base of the instrument behind the "business"
machinery. Fig. 3 (right). The molded high -frequency horn, together with its unit,
which is located at the top of the cabinet.
ploys two 6L6's in an ultra-linear type
output stage, providing a power output
of 22 watts. The power stage is flat
within ± IS db from 10 to 20,000 cps.
Playback equalization is of necessity
fixed, and conforms to the RIAA characteristic. Part of the equalization takes
place between the halves of the 12AX7
;preamplifier tube and part of it occurs
~n the input network to the cathode,follower volume-control stage. In addi:tion, a 12-dbjoctave rolloff filter is
lformed by a resistor-capacitor network
lin conjunction with the inductance of
·the pickup cartridge. Three positions of
rolloff are provided, best described by
Jhe title of the control. FREQUENCY
RANGE. These are FULL, MOlJERATE, and
LIMITED, selectable by a switch on the
amplifier chassis. In the FULL position,
rolloff begins at approximately 10,000
cps; in the MODERATE position; 6000 cps;
in the LIMITED position, 3500 cps.
These adjustments are made when
the instrument is installed, and it is
recommended that the frequency-range
switcfi be set to the highest position permitted by the condition of the records.
If new records are used throughout, and
are not played beyond the point where
the noise level becomes excessive, FULL
response is preferred. As the records become worn, the high-frequency response
may be reduced as required .
The frequency balancing networkcalled the FIDELITY EQUALIZER-is adjusted to suit the normal volume level
and the existing room acoustics. Thus,
for a live room the bass is boosted appreciably, while for a highly absorbent
room the bass response is left nearly
flat. This gives, in effect, a compensation for the listening level prevalent at
any particular location. This control is
operated by a knob on the amplifier
chassis.
The FIDELITY-EQUALIZER network
feeds the grid of a cathode follower,
with the volume control being a variable
resistor from the cathode to ground.
This permits running the volume-con-
INPUT
20 _
t---+-------<> L -F
SPEAKER
t---,--IWIN'---o H-F SPEAKER
18
OJ
'"
o--~--~-~----oCOMMON
475V +7500
20 _
4W
4W
4W
475V +
COMMON
DIVIDING NETWORK
0 .15MEG.
1W
:5
o
$
~
V3
12AU7
o
~
VOLUME CONTRCL
., IN 78·rpm MODEL ONLY
IFig. 4. Complet.e .s_che~.!Iti~ pf the amplifier. Circled figures indicate signal levels from typical phonograph records. Italic figures are d.c.
voltages. Insert-the dividing network.
AUDIO
www.americanradiohistory.com
AmericanRadioHistory.Com
•
DECEMBER, 1954
'Why
e life of your precious records
is prolonged with the
RACORD XA -100
In designing the Mirac:ord XA100 Record Changer partiiular attention
was paid to the perfection of the spindle. Conventional spindles often
caused the central hole of records to be dangerously enlarged, and
sometimes "egg-shaped". This distortion results in irregular revolution of the record and consequent distortio,n qf sound~
After exhaustive research the straight "MAGIC WAND"
" spindle wa~ ieyeloped~. This tevollJt!0ra,'Y spindle is
used exclu:sively on the Miracor,(l~Al 00 Record'
Changer.
Record Changer
nciple of the "Magic Wand"
,..;:
"1" ;
'_'""'I
~
~~#'
~
T;he "MAGIC WAND" spindle positions
the stack of records horizontally on
three resilient supports. During
a change of ,records, at no
time is the load on any
record greater than
the weight of a
@B': ~ngLe rec.o rd.
,
J~
Final switchlng-off: The last record
has dropped. The expansion spring
thus has greater lift and by means
of' the wire-release (E) Inside th~
pull.rod, effects the final s)Vitch-off.
exmechaof the "MAGIC
controls the
of the record on
~tllrntlJhlf!: the expansion
stretching in three directions
thewall of tile "MAGIC W"ND"
.the stack of records'0firmlYi the
'resilient supports release ' the bottom
perfectly horizontally; there is no friction
the released record and the record stack;
scratches are never caused on the record surfaces.
the record is released the stack remaining on thespindre
held by the three resilient supports, so that the central
of the bottom record is subie.cted to no dimensional strain.
luse of the construction of the "MAGIC WAND," the life of your
rds is extended and preseryed, and distortion of fh~ record is
inated. Only the Miracord XA 100 has the "MA~IC WANDIJ
all the other 'exclusive 'features that make it today's. most
,ht "after changer.
AUDIOGERSH CORPORATION
23 Park Place, New York 7, N. Y.
AUDIOGERSH CORPORATION
23 Park Place , t{e'M '(ork 7, N. Y.
Please send me descriptive literature.
Name
.. ............ .............................. .....................
Addr ... .......................................... ...................... 1
Exclusive distributors in the U.S. for Elac record players
www.americanradiohistory.com
AmericanRadioHistory.Com
+5
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FIDELITY
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CURVE
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28
2C
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2
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FREOUENCY
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FULL
FULL
MODERATE
LIM IT ED
FULL
FULL
FULL
FU ll
., .
,
1000
.
10000
FR EQUENCY IN CYC LES PER S ECON D
Fig. 5 (left). The 22-watt power amp lifier used in t he Model F. T his un it would make a good amplifier for a home syste m. Fig. 6 (r ight). Frequency respon se curves for the am plifier of Figs. 4 and 5.
trol leads a considerable distance from
the instrument without appreciable effect
on the high-frequency performance. The
volume control is a 3S,000-ohm rheostat
and requires only two wires. Being in
the cathode circuit, the impedance across
the control is never over 2000 ohms.
The volume-control circuit provides
compensation for the Fletcher-Munson
effect. At maximum volume setting of the
control, the output of the amplifier is substantially flat regardless of the setting
of the FIDELITY EQUALIZER. This permits operation of the phonograph at the
highest possible loudness level before
amplifier overload occurs. As the 'volume level is reduced, the bass is automatically increased- the amount and
region of the increase dependent upon
the setting of the FIDELITY EQUALIZER.
The curves shown in Fig. 6 tell the
story of the controls far better than mere
words can. The upper curves show the
performance of the amplifier when playing a test record cut to the RIAA characteristic, and with the volume control
at the maximum-volume position. Also
shown in the upper curves are the effects
of the FREQUENCY- RANGE control, giving
two degrees of rolloff below- the optimum-quality position, thus making it
possible to play records after their surface noise would be objectionable on the
fu ll-range system.
The lower curves show the response
with the volume-control setting" reduced
to lower the maximum volume by 20 db.
Here the effect of the FIDELITY EQUAL- IZER becomes noticeable, and in practice,
the sound quality at the lowered volume
retains adequate bass for good listening.
T he volume control is followed by
two voltage amplifiers, a cathodyne or
split-load phase splitter, and the output
stage. Feedback from the secondary of
the output transformer is 1-eturned to
the cathode of the stage preceding the
phase splitter.
The secondary of the output transformer is wound to a total impedance of
250 ohms to feed a 70.7-ohm constantvoltage speaker line when desired, and
is tapped at impedances of 0.7, 5, and 20
ohms. Combinations of these taps are
used to feed external 500- and 8-ohm
speakers as well as to provide the phonograph speaker system with four levels
of max imum power input.
Three types of remote speakers are
available-one is a high-quality corner
speaker using an 8-in. dual cone ; another is a wall-type enclosure using an
8-in. cone; and the third is a ceilingtype housing with a 12-in. dual cone.
Grille work on all of the remote speakers
is of perforated metal, eliminating the
possibility of damage by insects or overexuberant patrons. All speakers have a
six-step volume level control.
The filaments of the amplifier are excited whenever power to the instrument
is turned on; when a record is being
played, the muting relay contacts M R,
close the plate supply circuit and con- tacts MR. open a shunt across the. signal
circuit. This muting relay is controlled
by the operating mechanism, and serves
to eliminate noises of cycling or the
dropping of the stylus on the record. A
hum-balancing control-a potentiometer
across the heater circuit-adj usts for
minimum hum, and the whole amplifier
chassis floats on rubber grommets to
reduce microphonic noises to an absolute minimum .
The power supply is conventional,
using a SU4G as a rectifier with resist-
Fig. 7. The complete
recof'd
changer
mechanism of the
Model F juke box.
ance-capacitance filtering-a total of
120 ILf of capacitors being used in th~
smoothing circuit.
A simple chart in the instruction book
explains how to connect the phonograph
speaker system and the remote speakers
to equalize the volume throughout the
room, and eliminates the need for any
calculations on the part of the operator.
Recommended settings for the FIDELITY
EQUALIZER are also given in chart form
so as to provide a starting point in arriving at optimum sound quality.
The features of this amplifier that are
likely to be of greatest interest to the
engineer and the experimenter are those
of tone-quality control. While there are
no tone controls, as such, it is possible
to make a semi-fixed adjustment for the
acoustics of the room, and unless l:ecords
are played beyond their normally useful
life they may well be reproduced with
FULL frequency range. For home use it
should be possible to mount the FREQUENCY RANGE control on the panel, retaining.-the advantage of remote volume
control. It is probable that in the long
run better reproduction would result, for
this amplifier would eliminate the objections often heard regarding a multiplicity of controls. Most modern micro-
(Continued on page 42 )
_
AUDIO
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AmericanRadioHistory.Com
•
DECEMBER, 1954
KINGDOM·
LORENZ
ELECTROSTATIC
SPEAKER
This new tweeter covers the range
from ' 2000 to 20,000 cps, and comes
complete with full instructions ' for
connecti'1g to your present amplifier.
At all leading Hi-Fi
distributors
KINGDOM PRODUaS LTD.,
23 Park Place
New York 7, N. Y.
gilt!
A perfect
:Jo,.
I~e
Reco,.J :Jan
0,.
?jou,. Reeo,.J Colleclion!
THE
Disc-Charger
Imitated
But Not
Duplicated
This tiny plastic device contains a
radioactive material which constantly
ionizes the air in Its vicinity, drawing
off the static ele...triclty generated by
your records.
Static electricity causes records to attract and hold dUst. Use of the DiscCharger" eliminates the static electricity
and allows the stylus to pick up the dust
and clean the record in a few plays.
Records now no longer attract dust and
stay clean and noise free.
'h gram--clips to any pickup arm. See
your local distributor, or
shipped postpaid, only ....
$4 • 50
MERCURY SCIENTIFIC
PRODUCTS CORP.
1725 W. 7th ST.
LOS ANCELES 17. CALIF.
· Pat. App. For
there are Lady Bugle and Captain Jollyboy.
The ending, incidentally, is "Gothically"
eerie. Finally, Berners had a predilection
for intriguing titles: The Lady -in the
Pauper Ward, Bourgeois Waltzes, Funeral
March for a Rich Au,nt, etc. Unlike those of
Erik Satie, all of Berners' titles have a
point, or rather a barb in most instances.
Berners' varied . non-musical interests
naturally encourage the belief that he was
a sort of ingenious J ack-of-all-trades who
dabbled in the arts. After all, any composer
worth his salt should "live, breathe, eat and
sleep" music. Nevertheless, Berners was
decidedly a professional. His command of
orchestration was thorough, his theoretical
training was deeply ingrained, e.g., the
F1tglte in C Minor for Orcl~estra (1924),
and he possessed a keen understanding of
the demands and potentialities of the keyboard. The main point about Berners' works
is that, no matter how clever the intent.
brilliant musical satire is only effective in
the hands of a real craftsman-and Berners
was a musician down to his fingertips.
Berners' humor, therefore, is not the
one-dimensional variety of the cartoonist or
caricaturist. It often becomes a devastating
commentary on contemporary society. Let's
return, by way of illustration, to that set
of piano pieces, Three Little Flmeral
Ma,rches: 1) For a Statesman, 2) For a
Cana,r y, and 3) For a Rich Almt. The first
March, to quote the MGM jacket notes
"is appropriately pompous, but it also contains an element of sincere commentary. All
statesmen exist in an unreal atmosphere of
pomposity and are buried in that atmosphere, but, occasionally, dependent upon the
statesman, the pomposity becomes true
grandeur." And there is a hint of grandeur
in the statesman's dirge, just as there is
real pathos in the canary's end.
Lord Berners' supposed musical godfather was Erik Satie who was born in
Normandy and settled in Paris to eventually assume a position of great importance
among the avant-garde musicians of the
second decade of this century. Virgil
Thomson even went so far as to "parallel
the three German B's-Bach, Beethoven
and Brahms-with the S's of modern music
in descending order of significance [the
italics are mine]-Satie, Schonberg and
Stravinsky. Mr. Thomson may have gone
just a little overboard in his evaluation of
Satie, but there is no disputing one point:
Satie's influence was much greater than is
generally realized. He anticipated Debussy's
harmonic innovations by some fourteen
years in his Sarabandes and Gymnopedies.
H e. later became mother hen to a brood of
young musicians who already found the
impressionism of Debussy and Ravel as
old-fashioned as the faded opera-comiques
of Auber and BoieJdieu. Thus, Satie was
the musical prophet of not merely one, but
of two generations.
Satie the pioneer, however, is a less
familiar figure than Satie the humorist.
His Lewis Carrolt-like titles are still refreshing : Pieces in the Shape of a P ear,
Really Flabby Preludes (for a dog), Unappetizing ,Chorale, and Bureaucratic
Sonatina. Even more entertaining are his
"instructions" to the player: "Arm yourself with clairvoyance," "In the manner of
a nightingq).e with a toothach e," "A little
bloodily," a,hd "Without blushing a finger,"
'-CLASSIFIED----'
Rah.: 10' per wor. per in.ortlon fer ntDCHI...'"
.d.ertlsem.nts; 25' per word for 00 ....1'111.1 m.·
tl •• m.nts. Rat" art not. and no dl.eoants will ..
allowed. Copy mast bl .cc.mpanl.. IIy remlttaa .. I.
fall, and ma.t roach til. Now V.. k dee by tilt
ftrst of tho month pl'llCldlng til. .ata of Illao.
THE AUDIO EXCHANGE has the largest
selection of new and fully guaranteed used
eqnipment. Catalog of used equipment on reo
qu es t. Audio Exchange, Dept. AE. 159-19
Hillside Ave .. Jamaica 32. N. Y. OL 8-0445
AUDIO EXCHANGE EXCHANGES AUDIO
25-50% DISCOUNT, Factory-fresh guaran·
teed LP records. 69¢ and up ; send 20¢ for
catalogue. SOUTHWEST RECORD SALES.
Dept. A, 4710 Ca ro lin ~. Houston 4. Texas.
DIAMOND NEEDLES: Custom re·tlpping
of your phonograph needle or cartridge with
broadcast quality diamond. For Information
and price write to Transcriber Compnny (Din·
mond Stylus Manufacturers). 70 Pine Rt ..
A ttleboro. Ma ss.
RECORDING S,TUDIO CLEARANCE: Alter
600B $20; 603B in bame, $60; W. E. and
RCA 16-ln. playback arms with equalizers.
$65 each; Presto 50-watt 92A amplifier with
recording equalizers, $195; Pilot T-601 FM
tnner{ $25 ; 16-in. playback arm with GE
cartr dge. $15. RECO-ART. 1305 Markel
Rtreet, Philadelphia, Pa.
PRESTO RC-10-24 tape recorder wltb
900A1 amplifier. Cost $1200, sell in top condition for $600. Modified Van Eps 500-ohm
disc cntting h eads with hot sty lus attach·
ments, $85 each. RECO-ART. 1305 Market
St., Philadelphia. Pa.
FM ANTENNAS. Broad-band Yagis and
stan da rd t~' pes. Wholesale Su pply Co .• Lunen·
hurg, l\fass.
REL Precedent FM tuner, latest model.
never used, best offer. Roherts. 33 Sky Top
Dr. , Bridgeport 29 .. Conn.
KLIPSCHORN, $185; Klipsch high-fre·
quency horn with Stephens P-40 driver, $90'
RCA and Fairchild 16-in. two-speed turn:
tables, $35 and $45. Phone PE 8-3911 (New
Yorl,) Box CD-I, Audio.
CANADIANS-FM Antennas, Model RS·
52-M. Sold through leading jobbers. Suggested
list $7.65. Write for details. Tenatronics Lim ·
ited. Newmarket, Ontario.
FOR SALE: Three Magnecordettes. 2 yea rs
old, little nse. Excellent electrical and me·
chanical condition. One blonde, two mahogany. Cases scratched. $175 each. Also PT6-.J
and PT6-AH with 10-in. reel adapter In port·
able cases. 4 years old, nominal use. Perfect
mechanical and electrical condi tion, cases
and adapter worn. $275. Items guaran teed as
represented by Electro-Voice. Electro-Voice
Inc. , Bnchanan, Mich.. Attenti~n Cullen
Macpherson, Reprodncing Components Divl·
sion.
B:
ALLIED 16-in. Professional Recorder (same
6N), llke new. bargain. Box CD·2.
~bE~~.to
W AN'J.'ED: T~pesonic professional tape reo
corder. Must be sound, reasonable, carefully
packed when shipped. Also wish price on
Stephens 206AX 15-in. coaxial and/or Altec
LanSing 603B 15-in. speaker. Phone EM 2-3574
01' wire John A. C. Callan. 3819 Militnn
Road, N.W., Washington, D. C.
.
NEW Rek-O-Kut B-16B, $199. B-12H, $99.
Altec 820A system, $399. Pedersen PRT-1 Pre·
amp. $85. Craftsmen C1000 tuner. $139. Rox
CD-4, AUDIO.
TUBES-70% to 90% DISCOUNT. Govern men t , manufacturers, jobbers. etc.. SUI'plus. Guaran teed 1 year. Free catalog on requ est. <;nd illac ~rading, Dept. A, 231-07 Lin ·
den Blvd., JamaIca II, N. Y.
SELL: Presto 75a recorder, 87B amplifier.
Very little use. New $775, sell $450. Central
Recording Studios, 934 Kansas, Topeka, Kan·
sas.
Additional Classified Ads on page 64
AUDIO
62
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•
DECEMBER, 1954
The electrical circuitry of microphones is usually quite simple. In the
ma jority of cases where inductive microphones are used, such as dynamic,
ribbon or other moving conductor type ~,
the circuitry involved consists only of a
transformer and possibly an impedance
changing switch. In microphones such
as the Altec Lansing 21 type condenser
microphone, however, an impedance
transforming device such as a cathode
follower is necessary to transform the
tremendously high impedances of the
condenser microphone (several hundred
megohms) to a useable impedance that
can be coupled to an input transformer.
I
Conclusion
There a re no perfect microphones . .
The best achievement is a compromise
and the choice of important aspects in
a specialized microphone. An ideal microphone would be absolutely flat in the
range that must exceed somewha t the
hearing spectrum of the human ear. Its
dynamic range, which is its maximum
signal-to-noise ratio, must be at least
60 db. In this range, no distortions
should occur. Microphones that are omnidirectional should show no discrimination around their polar axis. However,
directional microphones sh0uld show the
same discrimination throughout their
frequency range, having a front to back
difference of at least 18 db. An ideal
microphone should also have a high
output so that less amplification would
be necessary to bring its level up to
useable proportions. To judge and evaluate the shortcomings' of microphones,
good acoustic measuring tools and good .
labo ratory techniques are a n absolute
necessity, without which some characteristics of the microphone would remain unknown factors. Good measuring
tools a re a lso essential in developing and
designing microphones and maintaining
their quality in production. Without
proper use of these instruments, microphone design is partially guesswork and
speci fications a re to a certain extent,
arbi trary.
It is hoped that this article will serve
as a guide to those persons who are interested in basic functions of standards
used to evaluate the many characteristics of a microphone. Because of its
shortn ess, the scope of this paper does
not allow speci fic details to be described.
ABOUT MUSIC
(from page 20)
among the people. Cartoons of Cleopatra
were scrawled on buildings throughout
Alexandria. During trips into town, she
was jeered at with cries of "Nosey !" Cleopatra finally fled the capital and underwent
successful plastic surgery. The rest is history. Another novel, Th e Camel, is an even
more fantastic tale dealing with the arrival on a winter's dawn of a camel in the
little English town of Slumbermere. The
_ animal rings the bell of the Vicar's house
and, from that moment on, Berners describes the visitor's impact upon the community. A couple of the characters are
given delightfully silly names; for example,
AUDIO
•
PARTRIDGE
OUTPUT TRANSFORMER
CORE DESIGN
For use in
HIGH QUALITY A.F. REPRODUCING EQUIPMENT
The P artridge UL2 p.p. transformeris specifically designed for really high quality audio
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back.
SOME
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REFERRED PRIMARY LOADING:
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Fullest technical data ru sh ed a ir
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TYPE W .W.F.B.
Bu-ill to the famous Williamson specification and ava il·
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PARTRIDGE
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ENGL AND
~~~de
.a udio anthology
.....
the 2nd audio anthology
Th. original audio .ntholOJY II still
bein, ordered by people who h.ve
worn out their first copy or who h.ve
lust l.arned about the book. Cont.ins
reprints of 37 articles which 'appeared
In AUDIO ENGINEERING from May
1947 throuth December 1949. An invaluable reference work on .udio in
the home.
_ _ _ _ _ _ _ _ _ _ _ _ CUT OUT -
the .2nd audio anthololn' continues
from where the first left off and contains reprints of articl.s from January
1950 through July 1952. In both
books the articles were brought up to
date, corrected where necessary, and
assembled by subject. the 2nd a • may
still be had with board cover.
MAIL TODAY - - - - - - - - - - - -
Book Division, Dept. 3V.
Redio Magazines, Inc.,
P. O. Box 629, Mineola, N. ·Y.
Sirs: Enclosed is 0
copies
copies
copies
check 0 money order for $ .. ..... Please send
of
audio anthology
(paper cover> @
of the 2nd audio anthology (paper cover> @
of the 2nd audio .nthololn' (board caved @
me
$2.00 each
$2.00 each
$3.00 each
Narrie Iplease print)
Address
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City ........................... . . . . . . . Zone . ..... State ... . . . ...... .... . .. . . .
61
DECEMBER, 1954
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ALL NE""
featu~e -packed
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•
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Yet the price is amazingly low.
CHECK th ese BELL RT-75 fea t ure s . . .
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• Th ree-speed M ech anism . .. 7!t2 ips, 3.'!4 ips,
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• Fast Forward and R ewind . .. 70 lee . rewind
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MICROPHONE CALIBRATION
(from page 32)
rating is on the voltage basis or the
power basis. The unfortunate part, however, is that numerically these systems
diffe r even though, when specified, the
results are the same.
The dynami c range of any microphone depends greatly on the noi se ,factor and random hum pickup emanating
fro m house wiring and other electrica l
or electronic equipment. Since random
noise is mainly due to thermal agitatioFl
and am plifi er hiss, it is very low in compar ison to hum pickup. To avoid interfer ence from inductively picked up hum ,
the mi crophones are usually wired to
avoid inductive loops. If transformer s
are used, they are usually well shieldect.
However, all hum cannot be excluded.
The remainder is low enough so as not
to interfere wi th the microphone's ability to pick up sounds without those offending factors being present. The measurement fo r hum pickup consists of placing the microphone within a loop of wire
that produces a 60-cps hum field of 10- 3
gauss. With no sound present which
would other wise interfer e with this
measurement, the mi crophone's output
io. directly measured in decibels and compared to a I milli watt reference. This
fi gure in decibels represents a rating
that evaluates the abi lity of the microphone to cancel no rmal hum levels. .
T he most impo rtant electrical characteri stic. of th e microphone is its impedance. W hether or not that impedance
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Bell~
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'"z
-
Circulation De pa rtme nt
\
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V
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<J)
MICROPHONE A
oQ.
'"
II::
I~
I-- .
<J)
~
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./
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c
'V'
IF YOU ARE MOVINC
-f-:" I-'
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Ex port Office 4 01 Broadw ay, NYC 13
A Subs id ia ry of Thompson Products, Inc.
Please not ify our Circulat ion Department
at least 5 weeks in advance. The Post
Office does not fo rward magazines sent
to wrong dest inat ions unless you pay additiona l postage, and we can NOT duplicate copies sen t to you once. To save
yourself, us, and the Post Office a headache, won't you please cooperate? When
not ifying us, please give you r old ad dress and your new add ress.
is terminated depends entirely on the
design of the input transformer used in
the amplifier. The present trerid is to
use unterminated transformers because
of the r esulting higher voltage output
that is applied to the input of the fi rst
a n~plifier tube. In either case, however,
the impedance of a microphone ·determines the amount of step-up ratio that
can be tolerated without interfering
lumped capacitance in the windings of
the transformer and the capacitance and
wiring involved in that circuitry. The
rated impedance is the a .c. resistance of
the microphone that is ,reflected by it.
A s an ex ample, if a microphone is rated
at 50 ohms, it should be matcl}ed to a
primary winding of a coupling transformer that has 'a SO-ohm impedance.
Most high-quality. microphones have a
choice of two or more impedances that
can be either switched or selected by
means of taps in their output terminals,
The choice of impedance depends entirely on the type and length of the
transmission line from the microphone
to the input transformer of an amplifier.
Ii low-capacitance lines are used, higher
impedances a re preferred. The reason
for this is that any line has resistance
and, therefore, acts to attenuate the
electrical energy due to res istive dissipation . On the other hand, if high-capacitance lines are used, low impedanceo
are preferred to avoid attelwation of the
extreme high-frequency response.
u
z
~
\
/>- 1'\
I-
f\
I IVI\
'\ J
/~ /
\
\
MICROPHONE B
o
- 60
~
- 65
v-
-
-
\ .
V
V
- 70
V
1\
- 75
20
V
I
\
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1\
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J
I~
100
IOPOO
t
20POO
FR EQU E NCY IN C YC LE S PER SECON D
RADIO MACAZINES, INC.
P. O. Box 629 Mineola N. Y.
Fig . 7. Altec's 670A J>ol ydirEicti onal mi,crophone. Cardioid respo nse compared to two ot her
cardioid mic ropho nes.
AUD IO
60
www.americanradiohistory.com
AmericanRadioHistory.Com
•
DECEMBER, 1954
provided by each recording machine which
instantly changes over the monitoring
loudspeaker from transmission to the reproducing pickup. The fr equency rang~ of
records is considered to be 50 to 10,000
cps. Another switch enables a signal of
constant amplitude and frequency to be fed
into the recording head so that when required a check of speed and characteristics can be carried out.
The static tape recording machines are
practically all of the same type being the
E.M.I. Model BTR.2 which is claimed to
have a freq uency range of 50 to 15,000 cps
at 15 in. per second. As these machines
cost about 10 times the price of a good
quality semi-professional tape recorder, it
is expected that they should give superb
service and they do so. A monitoring head
is provided in each, and the machines are
usually operated in pairs. Although they
will take larger reels of tape, the , B.B.C.
have adopted as a standard 2,400 ft. reels
and at the present time four different makes
of recording tape are used.
Ferrographs, which are semi-professional
tape recording and reproducing machines,
are installed in various studios so that they
can be operated by non-technical personnel
to check artistes' performances.
Dubbing from Tape to Disc
As mentioned previously, all recordings
which are to be kept over an extended
period are required on disc and consequently, there is quite a large amount of
re-recording fro m tape to disc. Although
the Recording Department maintain three
eight-hour shift s and work day and night,
it is realised that sometimes urgent stories
may be telephoned from abroad to th e N ews
Room and thus one machine is kept permanently threaded up and which can be operated instantaneously, by the News Editor
several floors above the floor in which the
majority of tape machines are located at
Broadcasting House.
In summing up the advantages and disadvantages of discs and tape, the following
comments were made to me by a B.B.C.
official.
Tape costs less because it can be used
again and again. It is not considered permanent enough for recordings to be kept
for archive purposes. Discs are much easier
to edit when sections of recordings are required for news transmissions or other
programmes. For outside recording, tape
equipment is generally much easier · and
simpler to use. On the other hand, when
tapes are brought back to the Broadcasting
Station, they are more difficult to identify
than discs particularly with news broadcasts where only extracts from recordings
may be required to be transmitted. Consequently, it is often more convenient to
immediately re-record the tape on to discs
before the recordings are· passed to the
News Editor. There is little to choose
between the cost of the recording equipment but high-quality tape reproducing
equipment, suitable for continuous use for
transmission purposes, is considerably more
expensive than disc reproducing equipment.
It will thus be realized that there is a
place for both disc and tape recording in
the B.B.C. Recording Department and the
general opinion is that eventually tape will
be the most used recording medium.
AUDIO
•
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"What to Do" and "How to Do" will guide your every move
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AUDIO
P. O. Box 629. Mineola. N. Y.
Enclosed Is D Check D Money Order for $ .. ... ....... . _. .... .. .
Please send a copy of each new issue of AUDIO for the next
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Subscription price. U.S.A •• Possessions, Canada and Mexico:
1 year $4.00; 2 years $7.00, all other countries $5.00 per year
- - - - - - _______________________ J
DECEMBER, 1954
59
www.americanradiohistory.com
AmericanRadioHistory.Com
LONDON LETTER
(from page 14)
dubbed ten times. The B.B.C prefer to for recording and/or reproducing. In the
make disc records of those programmes near future the static tape machines will be
which they wish to keep for posterity. With augmented by the installation of additional
characteristic thoroughness to be on the safe models to be used exclusively for reproside, they store the master records and the duction. There are 34 transportable mapres sings in separate locations. All discs chines which are large tape machines
or tape which have been recorded and are which can be taken from place to place and
not destined for the archives go into a 100 small battery tape machines.
The disc recording machines are made
current library for three months before they
are destroyed or, in the case of tape, are to the B.B.C.'s own design and incorporate
many novel features. Each motor is sprung
used again for a fresh recording.
It should be appreciated that the main ' and is balanced. The machines are comactivity of the B.B.C Recording Depart- pletely self-contained. and are always
ment is not to record programmes for operated in pairs. An ingenious scrolling
posterity but to record programmes for the motor is embodied so that the last few
converJience of the artistes and the pro- grooves of each disc are recorded quite wide
ducers. It is obvious that many artistes apart so that they can be indentified in
cannot appear in the evenings when the cueing when the records are reproduced
peak programmes are transmitted and it is and a change-over has to be made from one
therefore advantageous for the programmes record to another. This scrolling motor can
to be pre-recorded. The work of the De- be brought into operation during recording '
partment is, therefore, divided into pre- and causes the traversing carriage to move
recording programmes for transmission at about 15 times its normal speed. This
over the air and recording transmitted produces a very large opening out of the
programmes for subsequent transmission groove spacing. When a changeover is
and/or archive use. With disc machines being made from one machine to the other,
separate units are used for recording and 'the scrolling motors of both machines can
reproducing. There .are, for example, 96 be operated simultaneously from a single
static recording mcahines which 'will record button on the control desk and if this
78 r.p.m. or 33! r.p.m. and 31 mobile units. button is pressed for a fraction of a second
The Department is responsible for re- at the beginning and at the end of the overproducing 33! r.p.m. records but not the 78 lap period, the overlap portion can be
r.p.m. records. Consequently, Recording identified at a glance when discs are set up
Department engineers also operate 65 re- before transmission. The 16- and 17- in.
records at 33! r.p.m. provide about 15
producing units for 33! r.p.m.
minutes playing time. One disadvantage in
200,000 Discs per Annum
using 33! -r.p.m. instead of 78 r.p.m. is that
During last year more than 200,000 lac- it is much more difficult to cue the slower
quer discs were 'recorded but this year will speed records. It is considered that it is only
show a considerable decrease owing to the possible to cue these records to an accuracy
part change over from disc to tape. There of ± 1 second, whereas with 78's, ± 1 second
are only two manufacturers in Great Britain is comparatively easy.
The usual difficulty of dealing with
of lacquer coated discs and some of each of
these firms' products are used by the B.B.C. swarf is overcome by removing it pneuIn making the masters, however, the ser- matically. All recordings are monitored as
vices of 4 firms are available. The number they are made by placing a light-weight
of tape machines in use at present include pickup on the disc just behind the recording
head. For checking purposes, a switch is
118 static machines, which are used either
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AUDIO
58
www.americanradiohistory.com
AmericanRadioHistory.Com
•
DECEMBER, 1954
general (and very slight) rise in prices
generally outside of this field. Don't I
know-I've just had to up-date all the
prices in my book, which fir st appeared in
March of 1953, less than two years ago.
These new prices are still nominally net,
and the distribution, of course is still (in
the large) via the net-price dealerships.
But a big step in these two respects has
already been taken towards an eventual
new-ty'pe retail or "list" system. Just add
it all up and see for yourself.
It is therefore with considerable interest
that I note the first announcements to prospective ex hibitors at the Audio F air-Los
Angeles-the Audio F iesta- to come this
February, 1955. A very careful policy is
to be followed there that will exclude all
exhibition of w holes. The show is to be
a component show to the letter.
.
Exhibitors, as I understand it, will be
able to demonstrate assembled units, fo r
convenience and necessity, but with very
pointed restrictions, which, in my own
words, are about as follows:
1. They may demonstrate anything in
any assembled form they want, as long as
it is not for sale 'as a unit-a whole.
2. They may also demonstrate assembled
units that are for sale, but only when the
included components are also available
separately through regular audiophile (net) '
channels-as pa rts.
Now, if I have this right, it is a very
clear attempt to make a sha rp list-net
division, to separate the parts rigidly from
the wholes, while at the same time recognizing the inevi tability of the assembled
unit's appearance at the Fiesta. Yes, you
can have your assembled unit so long as it
is not a retail item.
No "hi- fi" phonographs of th e standard
retail brands will be on hand, of course.
Their insides aren't separately available.
GE's assembled machines are OK, though,
because they don't sell them that way, and
if they did it would be OK because the
insides are ava ilable as cOlJlponents, too.
( But GE can't sell them.)
But I wou ld hate to have to draw the
line between "yes" and "no" in th e case of
any one of dozens of new items I have
recently seen and heard, and I'm inclined
to offer aspirin to the harassed officials
who are going to have to decide. It would
almost be worth the transcontinental fare
just to see which items do get in and which
don't.
I offer not the slightest criticism of
the Fiesta management for this policy. I
can very well · understand, and so can you,
why it might be necessary as a precauti on
at this point. There is no reason at all
why an exposition management should be
expected to solve audio's major problems
for it in public-with thousands of the customers storming the joint! Establish a
temporary status quo, a truce, a moratorium, and let the fight between net and li st
resume after the show is over.
But the fact that this careful separation,
or attempted sepa ration, of parts and
wholes is necessary right now (and for
nex t spring ) shows how crucial has become
the burning question-
- j!lst w hat is a zCi/zole?
I'm willing to bet we'll know within
two year s.
AUDIO
•
BRUSH REDHEADS GIVE TOP PERFORMANCE
The high fidelity performance of Brush
Redheads has won them wide acceptance from makers of magnetic recording equipment. The record-reproduce
head, designed for dual-track recording on 7.t~inch tape, has unusually high
resolution, which provides an extended
frequency range. The Redhead is dimensionally stable, is unaffected by
moisture, a nd provides freedom from
mi crophonics. The companion erase
head has the same basic construction,
and is outstanding for efficient operation at very low power consumption .
For information on the complete line
of Brush magnetic heads-single and
multi-channel, write Brush Electronics
Company, Dept. ZZ·12, 3405 Perkins
Avenue, Cleveland 14, Ohio.
BRUSH ELECTRONICS
COMPANY
INDUSTRIAL AND RESEARCH INSTRUMENTS
PIEZO-ELECTRIC MATERIALS
ACOUSTIC DEVICES
MAGNETIC RECORDING EQUIPMENT
ULTRASONIC EQUIPMENT
formtrl,
The Brush Development C...
Brush Eltelronics Compa1l,
is an o"eratinc unit Df
Clevite Corpo r.olilm.
HYCOR
TYPE 4201
steps up to 12 db.
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~~d:ha, a maximum attenuation of 16 db.
has a maximum attenuation of 16 db.
el, slotted, 3 y," high . Maximum depth 7 y,".
impedance.
in-out.
8r idgt>iL:~",co'nstanl
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in 2 db steps, in·out key.
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DISTRIBUTOR
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11423 Vanowen St., No. Hollywood, Cal.
REPRESENTATIVES
Beebe Associates
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Harr:son J. Blind , 1616 Cord St.
Indianapolis 24, Ind iana
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EXPORT DIVISION
Morhan Exporting Corporation
458 Broadway, New Vork 13,
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DECEMBER, 1954
57
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discount that keeps the system as it is,
basically. For "net" prices can easily be
edged up until there is enough profit in
them to make possible "net" sales through
small dealers in small lots. That is now
happening, right and left, though the bigvolume sellers still predominate. What
keeps the net net is a remarkably rigid
business principle that applies to virtually
all fields of cons umer sales, far beyond the
tiny province of the hi-fi area-the principle
th at parts are one thing and tvho les another.
Net sales are, basically, parts sales. List
sales, retail, are basically wholes. Most of
our vast cons umer industry is split straight
through by this division. The large manufacturers have entirely separate parts divisions and wholes divisions, with huge separate dealership arrangements.
In these last few years what has happened
is that the entire development of the audio
home industry has been flying straight in
the face of this ' pri nciple-and now the
crisis is reached. Beginni ng with bona fide
parts, the net-price sellers have gradua lly
added services, sales rooms, consultation,
pre-wiring, package deals (all commented
upon and, indeed, recommended in this
department at length through the years, by
the way), until the erstwhile parts are now
so excruciatingly close to being grouped
the t;} _ __ ~___ J
into wholes that the di stin ction has almost
vanished I Yet it is still rigidly with us.
new~
There are "record players" with built-in
model 1811 full 12 watt
amplifier and controls, all but the speaker .
there are speaker systems including cabihigh fidelity amplifier
netry, there are chassis-type units with
everything but a beginning section and an
NOW, at moderate cost, you
end. The newer "package" off erings include
can own and enjoy a quality
so many lumped units with components
of musical re-creation virtually
built-in that in a blink of an eye they could
indistinguishable from the original
become compl ete wholes. They are- almost.
performance . Here is the ideal
but not quite.
" heart" for yo ur home music
And there is, ·this year, an almost omisystem, capable of reproducing the
nous number of actual, r eady-to-play, comfull musical range from vibrant
plete wholes made up of components. Omibass through thrilling treble with
nous only in the sense their suggestion of
the full emotional depth and
impending things of vast impo rtance to
meaning of the original music.
come in the home audio fi eld.
Here is the finest audio achievement,
For when does a collection of parts bedesigned to bring you the
come a whole? That is the incredibly tickultimate in enduring listening pleasure.
lish question that now ari ses! If it remains
with every desirable feature for a collection of parts, assembled, then it is,
according to present rigid standards, a
superb musical reproduction ••• net-price
item, saleable along wi th the parts
, • Full 12 watts output. Response, ± 0.5
themselves. But if it is suddenly to be
db, ;l0-20,OOO cps .• 3 Response Curves
judged a whole-then what?
to bring out the full fidelity in all types
You'll note the many developing contraand makes of records. Microphone input
dictions that a re now providing a multitude
for entertainment and recording. Separate
of eloquent straws in the wind, forecasting
Bass and Treble tone controls. Choice of
what is to come.
regular or "equal loudness" control
• Inputs for GE or Pickering cartridge,
The big companies, in varying· degrees,
tape, tuner, and microphone. Removable
are in the hi-fi market on both sides of the
panel for easy mounting ...
fence, retail (wholes) and net (parts)PLUS every other desirable feature
and, if you ask me, they're having a hto create a new d,mension .
of a time trying to figure out wh ~t'~ they
in sound for your home.·
stand, if they do stand! Some farm out the
parts end to parts makers and raise the
price of the resulting product to what
amounts to retail-yet sell it stric;tly on
the: net side of their own vast 'distribution
fence (so as to avoid competition with their
r etail lines). Others, GE, for example, big
Hear the
RAULAND 1811
makers who manufact ure many of their
Amplifier at your
own audio parts, find themselves in the odd
HI-Fi dealer, or write
for full details.
position of competing, or trying not to compete, with their own manufactured products.
RAULAND-BORG CORPORAIION GE~s parts division in the audio field, which
, 35,.15: W.~ddiso.n,.St., Dept. C, Chicago. 1 8, III~, . . · began , 0Jjler.a~ion~ aAew years ago with no
, \11I:{1 Y/
56
mure than a cartridge and a speaker or
two, now-thanks to its own enterprise
and success-has' branched out until it
offers the parts for a virtually complete
hi-fi system, even to the cabinetry, in which
the parts can go. Yet it can not take the
last step and assemble these parts into
wholes without conflicting with its sister
department that makes whole (retail) hom ~
instruments. What to do?
GE .exhibited its parts at the Fair nicely
assembled into wholes. 'But the whole>
were not for ' sale.
And meanwhile as a fiery goad-backed
by a huge public demand-many small com·
panies, especially the newer ones, a re strik·
ing straight out at this middle ground
where the big companies dare not tread.
with complete hi-fi phonographs that, nev·
ertheless, are basically assemblies of com·
ponents, separate units, often described in
de:tail. But at the same time, to add confusion, most of the strictly retail one-piece
whole "hi-fi" machines are also now being
described in similar terms-a 6-watt push·
pull amplifier, special ultra-hi-fi six-inch
speaker" and the like. The ad men leilrn
fast.
Thus the pactical dividing line between
retail-wholes and assembled-parts is in·
creasingly hard to pin down, even with
very careful investigation. Are these in·
between items to fall into the retail-whol ~
camp or the ' assembl ed-parts area? Are
they to rate as net (and sell through the
net deal ership) or r etail (and sell through
a wholly different dealershi p) ; or can they
sell in both ways at once and, if so, at one
price or two prices?
It's rapidly becoming impossible to say.
The divisions become more and more can·
fused. Indeed, there is such variety in pres·
ent offerings a lready, that the separation
simply does not exist in respect to the
equipment itself. The variants run all the
way from genuine assembl ed separate-part~
systems, each part identified and known.
by maker and model, through to the
straight retail "hi-fi" phonograp h, its in·
sides inextricably wired into one piece by
its own manufacturer; the intermediate
steps-the most significant of all for the
future-include many new machines with
some standard components and some "special" (i.e. not available also as a separate
unit) and this would seem to be the probable norm for the futur e development of
this new in-between area.
It's already happening in an indirect sort
of way; this trend to retail. Prices are still
net, but notice two significant things.
directly and profoundly related :
1. Component hi-fi is getting fancier,
with more trimmings, more service at- ·
tached. Better looks, more direct application to th e home and to home decor, more
plush advertising. All of this-on top of
the fancy-type show-rooms of the last few
years-is retail-type merchandising. It's
90 per cent retail already, if you take "net"
or wholesale selling for what it's supposed
to be, and is in other fields. Hi-fi components are going retail faster and faster in
these aspects.
2. For these better looks, for better performance, more trimmings, better service
and - sales-help-we are getting higher
prices. There has been a very marked rise
in the last year, beyond and above the
AUDIO
www.americanradiohistory.com
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• . DECEMBER, 1954
5. When are these Exhibitofs going to
get some com mon 'Horse Sense'? It's been
a long time since Barnum."
You may laugh this person off as a
crank if you will, but I would advise you
(a potentia l 1955 exhibitor) not to. As you
may read, he is both sharp-eyed and a
purposeful shopper, who has already bought
audio and intends to buy more. He is unlike
many another Fair visitor merely in that he
is brash enough to speak his mind-though
naturally this was not intended for print!
I have omitted a few other points he made,
mostly because I couldn't disguise them
and I, unlike him, have a responsibility
towards exhibitors as much as towards the
Fair visitor.
I wonder just how many people did think
the Fair was a Barnum circus, though? I
mean this entirely constructively. I am
dead sure that a lot of potential audio customers did-once again. There are hundreds
of thousands of them remember, all over
the country, and the few who reached the
Fair itself reported back to a vast number,
at home, exactly how they felt.
Isn't it time that th e Fairs and the audio
industry completed the growing-up process ?
Should we not, at this point, look further
forward and realize that, hi-fi boom or no,
in the long run audio cannot depend on
these short-lived crazes for mere sound,
but must build on the far deeper, more
permanent and more trustworthy values
ot real sound reproduction-the enduring
interest in the content of the sound ?
It seems to me that the various Fairs
must somehow come to reflect this interest
more than they now do. We're now attracting the lunatic fringe--a big fringe, but a
mighty un stable one. Don't lose the solid
citizens.
As I've said for many a yearThe Business of Audio is Music.
Yes, other kinds of content have made
big gains-Sounds of Our Times (which
are interesting in themselves, often), poetry
and prose, complete shows, plays, documenta ries, teachin g records, and so on. But
music is still 99 per cent of the content of
recorded sound. And so-we need th e
music-lovers. Amen.
3. Crisis-The Whole vs. The Parts
( Feb. 1955)
The great struggle of the net price vs.
the list price-and all the complex system
of manufacture and distribution that is represented by these two terms-is entering
a decisive and exciting phase in the fastniov ing history of hi-fi.
Hi-fi for the home (call it that for lack
of a better term) started, as we all know,
in the wholesale radio parts stores, where
the few gadgeteer amateu rs and side-lining
professionals who wanted separate amplifiers, cartridges, and the like were perforce required to go-there wasn't any
retail outlet for such "professional" items.
The subsequent history of this remarkable
and atypical business has been based, accordingly, on the net sales system, now
renamed audiophile net or similar comfortable term. It still is based on the net,
nominally, though the list price for separate
parts now scarcely exists at all, even in
advertising.
But it is not merely the supposed greater
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55
www.americanradiohistory.com
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Y
/
Hi-Fidelity
dynamic
microphone
ere.
only
Edward latnatl Canby
Fairly
Criti~al
eff ect so fa r I wi ll try a better scheme and
quote a sli~htly sobering letter I' ve just
to mend a dizzy error
r
eceived. It' s not the only one. F rankly,
in the September "Tapes fro m Tube"-though as a whole I thoroughly enj oyed
not in the description of the new means
the Fair and marveled at its complexity,
fo r playing tape but in my crediting my
source as a "part of a column by R. D . its wealth of interesting material and its
D arrell." It was part of a column all right. excellent organization, I was really shocked
at th e cr udeness of sound that some di sBut the author, Mr . Da rrell tells me, was
players persist in blas ting, fort~ for ?u r
Robert Oakes Jordan, writing in his S atsupposed
delectation. I don t mmd sayl11g
urday R eview "World of T ape" departth at I walked out of three or four rooms
ment. A ll credit to Mr. ]. as well as my
in a fury at the insultin g barrage of high
apologies to him and Mr. D .
powered noise inside.
Darrell (who has had extensive libra ry
Y es, the audio fans are possibly now the
experi ence and would never be caught withmain ta rget for the F air ; and definitely th e
out complete information at his fin ger-tips)
aud io fan s are the ones who demand louder
has sent me the original publi shed discusand louder music, who occupy all the fr ont
sion in E lectronics, October, 1953, with
rows and do all the kibitzing. But there
interesting pictures and diagrarps of the
a re hundreds and hundreds of musical peoplayback tube. Skellett's complete paper ,
ple who come to the F air to see what audio
from which this article was derived, was
can do for their music, and who go away
presented at an IRE meeting at San Anagain bewildered. I once called these
tonio, T exas F ebruary 7, 1953, and later
people "mousy"--they stay in the back and
printed in full in the IRE -PGA T mnsackeep their own coun sel and let the audio
tions, AU -2, #1, J an.-Feb. 1954, along
fa ns do the talking. But they think hard
with another paper on related experi ments.
thoughts about many an exhibitor and th e
The official authors of this material are
net eff ect, I assure you, is not good. But
Skellett Leveridge, and Gratian.
let my correspondent speak for me. I'll cenOddl; enough, M r. D arrell says, he did
sor names ; you can fill in with your own
write a description of this same electronchoice. Italics are my inserts.
beam playback tube fo r the same journal,
" ... I've j us t returned home fr om a visit
the S aturday R eview, a good many month s
t'l the New Y ork Audio Fair and must
before the J ordan description--the one that
state I'm fa r f1"01'11 impressed, and had I
I saw. Unfortunately, the Darrell item
vi sited one of these shows before I bought
wasn't published, due to space di ffic ulti es.
equipment I'd neve r have bought any . . .
It is his impression, I gather, that some
[the equipment was ] overdriven to a point
very tough matters of shielding will have
of a nnoyance and my ea rs are sti ll ringing."
to be solved before th e tube gets into gen( T all e that, m y friends!)
eral use. It operates at a dreadfully low
"A few notes on the Fair :
level. Its most immediately likely applica1. The
is a phony. ( These
tion, as already suggested, will be for
amate'ltrS are not as d~,mb as we thl:nk th ey
hi gh-speed tape duplication.
"aI'e.)
F ina lly, D arrell voices a hope that a lot
2. ---------'s speake r sys tem was "blastof us have had, on and off, that--someday
ing" too loud to pass on any merits one
--somebody will invent a practical grooveway or the other. (I have fl esh e~ r s, neither
scanning device, to play disc records withgo ld nor t in.)
out physical contact with th e g rooves. The
3. ' How can a master (disc) cut sound
principle would doubtless be similar to that
better than the original tape, especially
of the magnetic playback tube, with the
afte r so many plays? And the commercial
same advantages of inertia-less operation, copy, 2nd, 3rd, 4th printing ? The equal of
minus all mechanical motion and mi nus th e
the master ? Who' s kidding who? ( ThI s
generation of a cur(ent. P ossibly th e Skelwas the r esult of som e no t-too -well-calculett tube is the beginning of an answer.
lated shozvmanship, I'd say; the actua.l demonstration zvas in -itself reasonable, bllt
2. Barnum-again ? (October 195 4)
missed its aim. )
4. I really wanted to hear th e - - -- I suppose I could print again my remarks
tuner but they were "out fo r supper" fo r
of several previous years conce rning th e
quite a few hours. I want a new FM tuner
annual New York Audio Fair in its louder
to fit a certain cabinet; my [present one]
and tinnier aspects, for they still apply. But
is too wide. But I expect my mOTley' s
ra ther than repeat the same old record,
worth.
which hasn't seemed to have any great
1. Erratum
I
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AUDIO
54
www.americanradiohistory.com
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•
DECEMBER, 1954
• Cinema.Scope Recor d-Repr oduce Hea d s.
R ecently a dded to the Brush line of t a p e
record ing a c cessories are the Model B K 1544 -R reco rding h ead, a nd the c om pa n io n Mode l BK -1544 for r eprodu ction. Both
head s a r p. d esi g n ed to m eet th e s p eci fi cations of Ci nemaScope a pplicati on s, a nd
co nta in a numb er of f eatures w hic h h a v e
been developed by Brush en g in eer s. Both
h ead s in corp o r a te a b a la n ced m a gn etic
••
fantasticl
struc t u r e w i th g a ps a t fr ont an d b ack, a ll
ga ps bein g in pre cise a l ignm ent. H ead assemblies a re non-micro ph onic and i m pervio us to moi sture. Mu-m etal s hields isola t e indiv idua l ch a nnel s , an d the entire
unit is cas t in high -tempera ture resin.
De t a iled d escription of the Cine m aScope
hea d m ay b e obtain ed fr om Brush E le ctronics Compa ny, Component D ept. RT-3,
H4 05 P erkins Ave., Clevela nd 14, Ohi o.
NEW LITERATURE
(from page 8 )
• Minne s ota Mining and M a.nufacturing
C;:o., St. Pa ul, Minn. is n ow di s tributin g
Bu ll e tin No . 30 of t h eir " S ound T a lk"
seri es whi ch d e scribes p h ys ical a nd m a gnetic specifica tions of th e new "S cot ch"
bran d N o. 1 90 "E xtra Pla y" m a gnetic
tape, and is i llu str a t ed by two cha rts
s h ow ing compa rat ive fr equen cy r espon s e
c u rves and layer- to-layer s igna l tra n s f e r .
I n c l uded in t h e d a t a are optimum op e l'ating con ditions an d a com pari so n of o per ation a t both h ig h a nd low fr eque n c ies
for different bia s curr en t s . Copy will b e
s e n t on r eq u es t.
• The Dubbings Compa ny, 41-10 45th St.,
Lo ng Isla nd City 4, N. Y. has just iss u ed
Bu lletin C, a 12-page pamph le t de s cribing
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Copy i s ava ila b le f r ee u p on r e quest .
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Feb. 17-18- National Conference on Transistor Circuits. Irvine Auditorium, Univ.
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T rade Mark
53
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AmericanRadioHistory.Com
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AUDIO
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DECEMBER, 1954
, AMPEX 600
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Recording distortion is negligible . The Mod e l 600 is e xtremely easy to
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1955 HIGH FIDELITY CATALOG
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DECEMBER, 1954
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NEW PRODUCTS
• Tape Collector's Cabinet. Introduced as
the "Collector's Cabinet," this new item
recently announ ced by the makers of Irish
brand recording tape will be a welcome
gift to tape recording fans. The "Collector's Cabinet" solves two of the main
'problems of tape 'recorder users; (1) stor-
• Brociner Mark 12 Anlplifier. In an effort
to satisfy the need for a compact highfidelity, amplifier meeting professional operating standards, yet modest in cost, the
new Mark 12 recently introduced by BrocineI' makes liberal u se of printed circuitry. There is no chassis as s uch. The
printed-circuit technique is h ere applied
.'----.._..-
• "Tri-Fi" Beproducer. Althou gh small
onough to fit an average bookshelf and
only two feet In l ength, the new Teeco
" Symphonette" is a complete three-speaker
rEproducer system with built-in crossover
networks. Separate speakers are u sed for
.----..
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low, middle, and high frequencies. According to the manuFacturer, power handling capacity is 20 watts an d freq u ency
range is 20 to 14,000 cps. The Symphonette
is availa ble in three finishes; l eatherette
cover, blonde, and mahogany. Truton e
Electronics, Inc., 812- 14 N. Highlan d Ave ..
Los Angeles 38, Calif.
a ge, a nd (2) identification of recorded
reels. The cabinet holds six reels a nd
makes a h an dsome storage chest. It contains three 600 -ft. reels of Irish brand
profession a l tape, one roll of splicing tape,
one 1'50-ft. roll of leader stock, twenty
reel tabs, one empty 600-ft. reel an d one
empty ISO-ft . reel. ORRadio Indu stri es,
Inc., T-120 Marvyn Road, Opelika, Ala.
• Audio Oscillator. E ssentially flat output
over the r ange f r om 12 cps to 1 mc with
s ix overlapping scal es, m ak es the new
Beckman Model 301 Utility Audio Oscillator a n instrum ent of great versati lity
for la bora tory a nd maintenance applications. Distortion is un der 0.5 per cent at
the lower frequ e ncies. Ham level is d own
52 db f rom 1000 cps to 1 mc, a nd down 43
• AM-FM Tuner Kit. Bandwidth of 200 k c
on FM, tuned r -f stages, twp limiters,
a nd di scr iminator, are among the features of the new Imperial V FM-AM
Tuner Kit. FM sens itivity is 5 a nd 10
'microvolts for 20 an d 30 db quieting, respectiv.e ly. AM t uni ng r ange is 530 to
for the first t im e commercia lly to a com plete a u dio am plifi er, achi eving exceptional compactnes s , stability of p erformance, and economical prodjlction. Power
output is 12 watts with l ess than 0.1 per
cont distortion. Freq u ency r esponse is 20
to 20,000 cps within 1 db . Sepa rate tUrTIoyer and roll-off co ntrol s a r e s upplie d for
record compensation. Continuous b ass and
treb le controls permit 16 db of boost and
c ut. Dimensions are on ly 4'4," high X 10%"
long x 8" d ee p. Brociner E lectronics Labor a tory, 344 E. 32nd St., New York 16, N. Y.
• High-FideUty Headphones. Frequency
rr.sponse from 50 to 10,000 cps is afforded
by S. G. Brown T ype K precision headphones, manufactured in Great Britain
and distributed in the United States by
British Industries Corporation, 164 Duane
1650 I{c; FM tuning r ange is 88 to 108 mc .
Chassis dimensions are 9
long x 5" high
x 8" deep. The unit is supplied complete
wit h a ll parts, t u bes, and pictorial a nd
sch em atic diagrams. Further in formatio n
an d performance d ata are available from
Approved E lectronic Instrument Corporation, 928 Broadway, New York 10, N. Y.
*"
• Audio Analyzer. Virtua ll y a ll of the
basic tests n ecessary for the evaluation
oi a u dio performance of amplifiers, oscillators, and simi lar devices, m ay be performe d by the Heathkit Model AA-1 Audio
st. , New York 13, N. Y. Built around modb from 60 to 1000 cps. Each instrument
is i·n divid ually calibrated and maintains
all accuracy of ± 2 per cent under normal
operating conditions. Output is 10 volts
into 600 ohms on all scales. Manufactured
by Shasta Division, B eckman Instruments,
Inc., P. O. Box 296, Station A, Richmond,
Calif.
tor assemblies of the moving-coil type,
the phones utilize Bakelized cone · diaphragms. Flux density is 6000 lines. WeIlsuited for critical professional monitoring,
the Brown headset is supplied complete
with foam rubber cushions and a onepiece rubber-covered connection cord with
molded rubber crotch.
Analyzer. The unit functions as three instruments in one, an a. c. VTVM, a wattmeter, and an intermodulation distortion
analyzer. Featu ring built-in loa d resistors
of 4, 8, 16, a nd 600 ohms, and built-in
low- an d high-frequency oscillators, the
AUDIO
50
www.americanradiohistory.com
AmericanRadioHistory.Com
•
DECEMBER, 1954
clSes I No more than are .!lach's "Well Tempered
Clavier" prelud es and fugues. These simple little
nursery-style tunes are captivatingly lovely if
you are sens itive to direct, simple, intuitive musicmaking, and the pla ying by Kozma is miraculously
beautiful. It t akes a big artist to play simple
music beauti fully. Lovely piano tone. too.
"" Bela Bartok (Allegro Barbaro, Rumanian
Folk Dances, 15 Hung. Peasant Songs, For
Children, Suite, op. 14.) Gyorgy Sandor,
Columbia ML 4868
Diano.
Twenty of the forty little pieces above also apvear in this recording. Sandor, however, is a
pianist of a very different sort, a big concert performer and dramatist with a dynamic, tense piano
personality splendid for the more involved works
but alien to the simple children's music, which
under his fing ers mistakenly tries to be "big
.tuff." Sandor brings out the vital barbarism in
the furious B artok temperament; but Kozma is
in tune wit h the equally t elling g entleness and
compassion in the great Bartok soul.
Sandor is excellent in the showy and short
Suite, the Allegro Barbaro, also short, and the
popular and "concert-genic" Rumanian Folk
Dances. The Peasant Song s, instrumenta l equivalents of the sung folk songs reviewed above, are
again on the hard, dynamic side, lacking in simplicity in the playing_ The piano recorded sound
IS hard, too, lacking in fullness, of the type current in Columbia's 30th Street studios in 1951
when these were made.
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Oddities in Brief
x: Wagner: Symphony in C Major; Polonia
Overture. Radio Berlin Symphony, Pflugerj
Guhl.
Urania URLP. 7116
Yes-Richard Wagner, of the operas I The
Iymphony wa s composed in his teens, after study
of Beethoven and Mozart ; the overture is from
the same period and the t wo were revived in
Wagner's last years (Wagner even re-composed
some parts that had been lost) and again shortly
after his dea th.
The sympbony is a preposterous but virile imitation of B eethoven, a caricature, rather J full of
pompous pronouncements in the style of the
Beethoven overtures, but also strongly influenced
b1 Weber. S illy stuff, but interesting-for it is
• miracle tha t such a calculating but utterly u n organized musical talent could have p erfected
Itself into the genius of fifty years later. The
Overture is even more absurdly pompous, but
also interesting for any Wa",ner-lover. Both
nicely played.
Shostakovitch: Symphony # 1 0 (1953).
Leningrad Philharmonic, Mravinsky.
Concert Hall CHS 1313
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1955 CATALOG
Hold on-for by the time this review is in
the Columbia-Mitropoulos version, made in
:-;rew York, will be out. But t h is one has the advantage of being conducted by the m an who led
the premiere ' of the new sym phony in Russia last
year (and presuma bly the same players) , which
gives it a stamp of authority as an officia l Russian
version.
As for the music-nothing at all s ensation a l,
alas. I like the 9th far better. This shows S.'s
usual propensity for running a good thing into
the ground ; of all our more gifted comp osers h e
is surely the most undisciplined when it comes
to conciseness. There are lovely t hings here, in detail, but much of it is more of the same old h ig htension m a rch stuff, and t oo much of it is
monotonou ~ly, obstinately unvaried, at len gth.
Russian recording is g etting good, except for
the t ell-ta le presence of drastic limiter action (or
monitoring?) that makes loud and soft pa rts about
the same volume. (Leeds-authorized. )
~rint
Write today for
ALLIED'S 308-page
1955 Catalog-your
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If it's anything in Hi-Fi,
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ALLIED RADIO CORP., Dept. 17-M-4
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49
DECEMBER, 1954
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.. . . . .
. . . . .' . .
Bartok: Concerto for Orchestra. Minneapolis Symphony, Dorati.
Mercury MG 50033
C
This makes a /ine companion hi-fi piece to go
with the above; it has similar qualities, ex.
aggerated. The recording is Mercury's most
stunning, with the characteristic close· up almost
dead sound-but for this very reason this is the
/irst version since the old R einer·Columbia on 78
and a n early LP that does justice to the special
kind of scoring in this now-familiar mus.ic, which
fea tures a constant play of orchestral detail-work,
pairs of trumpets, oboes, clarinets, small <"solo"
groups of instruments, all within the larger
orchestra. (That is why it is a concerto for
orchestra.) Over-all distant miking, fine fOI
Brahms and Wagner, is wholly wrong for thi.
music and so Mercury's cIose~ up job is, as a
recording, much preferable to the Angel and
London versions with their standard big-livene..
sound.
I can't say as much for the perform ance, which.
oddly, is entirely right style-wise, where othel
versions miss the whole flavor of the work, yet is
remarkably hard and unmusical. Nevertheless, this
makes excitin g hi·fi listening an d it's a marveioul
look inside an or chestra and inside a fabulously
we ll~m ade score.
You 'C an Enjoy
HIGH FIDELITY
al Lo"" Cosl ...
II<d Bartok: The_ Wooden Prince
(balletl .
New Symphony, ·S usskind.
Bartok BR 308 (2)
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Peter Bartok here continues his long-rang.
project of recording all of his father's music that
is unlikely to appear on other record labels. This
is a vast and unwieldy early ballet score (1914-16)
of positively enormous proportions and it was an
ambitious and idealistic task to put it on records.
Four long LP sides, an enormous orchestra.
The music, oddly enough, in spite of its dis·
sonance, seems t erribly dated and old-fashioned.
Old-fashioned, I ~hould add quickly, in a way
that may please man y list eners, for this is of th.
Fire Bird schooi-, out of late Richard Strauss, a
turgid, thick, highly-Romantic score for very large
orchestra, playing up the typical lat e-Romantic
preoccupation with elves and fairies and magic
and princes and princesses with an only too typical
lack of humor and lightness and conciseness, with
that characteristic overblown sound, those great.
gusty climaxes (with screeching strings and the
inevitable cymbal crash at each "peak") that go
with the tail-end of 19th century Romanticism. A,
you can by now guess, I don't like it much.
I would not deny that, as a score from one 01
our musical greats it has all sort s of special inter·
est, in its orchestration, in its dissonant harmonies
and powerful modern-type m otives. The work of
a big man-but it's unformed and fussy even so.
and much too big for its boots. The Second Piano
Concerto, above comes like a breath of sweet
spring after this I
Hi-fi? FTom Peter Bartok, of course. Pickuv
is evidently single-mike, at a considerable distance
and rather n arrow in liveness, but technically the
disc is top-rank. If you like modern-type big
Romantic scores , this is your sound.
S8 Bartok: Songs, Opus 16; Hungarian Folk
Songs. Magda Laszlo, sop., Franz Holetschek, pf.
Westminister WL 5283
The distinction between folk and Hart" songs
is neatly illustrated on the two sides of this disc.
The Hart" songs, modern of course, will be mostly
incomprehensible to the average listener, though
those who are grounded in the enjoyment of
German lieder and French song will understand
them and enjoy them. But the folk song settings
on the reverse, though just as dissonant and
modem in the piano part, are immediately en·
joyable to anybody who "likes a good time"or a good dance. Bartok is still the only major
composer I know who can set folk tunes with
dissonant accom paniment s that are entirely in
spirit and in harmony with the tunes :themselves.
Any listener can hear it.
The folk songs were also recorded by the tenor
Chabay, for Peter Bartok; this is a milder soprano performance though a lively one, and th,
pianist is excellent .
I
t* Bartok: For Children, vol.
Forty little pieces, graded, for children's piano
st u dy- I used to play some of the simple ones
myself-but don't think these are mere exer-
AUDIO
48
www.americanradiohistory.com
AmericanRadioHistory.Com
1. Tibor
Bartok BR 919
Kozma, piano.
•
DECEMBER, 1954
press ions of deta il, I was definitely aware of a
smoothness, an u npretentious natur alness of
sound, an u n-h urting q ua lity, that clearly signals
unus ua lly low distor tion com ponents, and this was
particularly noticeable in the louder passages,
where d istortion normally is at its worst. C larity
of detail work was a secondary product of this
over-all smoothness, as I heard it.
I was une..'Cpectedly pleased by C. G. McProud's
straigh tforward and honest accompany ing booklet, which sets forth the technical consideartions
for a hi-fi recording and descr ibes b i-fi listening
from the engineer's point of view. We've had so
much p urp le language concerning h i-fi bf lat e,
this little booklet is a pleasure to read and J
recommend it to music lovers who would like to
know how an engineer and c;on fessed non -mu sician
-really feels about listening. Not a trace of the
usual h i-fi publicity-type writing here_ There's a
:running stop-watch-timed. comment on the two
pieces that is rem arkably m usical, thanks to Mr.
McProud's extensive experim ents with score following d uring h is preparat ion of the not es.
H Tchaikowsky: Romeo and Juliet ; Marche
Slave; 1812 Overture. Lo ndon Symphony,
Sche rch e n .
Westminister WL 5282.
I 've reached capacity a lready on listening to
these scores; I'll let you do the listening, thanks ;
but I mention the record for a reason of COll-siderable interest, the fact that this recording (a).
is a st andard West m inster job with the same
musicians and conduct or as in the special "Lab"
record ing above, and ther efore a good m eans of
-comparing the regular and s pecial issues of the
·company; and (b) because in add it ion, an ex.eerpt fro m this same recording is ava ilab le on
tape (9 minutes) as the fi r st "Treasure Tape"
·.offering from the Encore tape peop le. ( SO¢ , returnab le when you buy a roll of blank Encor e
tape.) T he tape should be high quality 7Y.H
(half-track), for Ampex-Concertone playback
-equalizat ion _ A fine chance to compare a top
quality d isc w ith its recorded tape equivalent
.and I adv ice anyone who wonders about junking
his disc li brary for tape to make the test in
·person. Noth ing like first·hand experience, on
your own equipment.
(Not e that the fu ll-len g th R CA Vict or t apes
are also avai lab le on RCA Victor d iscs, t hou g h
.direct comparison will be pretty costly.)
ern tsmon
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Note a lso, by t h e way, th at though recorded
·tape seem ed to be booming at last fall's Audio
'Fair in New York 'a nd we are seeing a constant
series of new announcements, the actual tapes
.are mostl y still to corne; we've bad DO new new
·review t apes. Not even t h e RCA V ictors, which
are still officially "out on loan" to somebody
·else, according to t he com pany. (We' ll just have
t o wait our turn.) It will be some tim e before
recorded tapes begin act ua ll y t o compete with
·discs in a practical way.
:Hi-Fi Bartok
# 2, #3.
*0 Ba r tok: Piano Concerti
Ed ith
Vie nna
Sta te
Ope ra
O rch .,
'Farnadi ;
:Scherchen _
Westminster WL 5249.
I suggest that every hi-fi fan who a lso h appens
·to like the kind of brassy dissonance we get in
-much modern high-powered jazz and show music
should now lend his couple of ears t o Bartok as
..a hi·fi com poser. Bartok, of co urse, had no more
idea of hi-fi than did old Rimsy-Korsakoff and
Piotr I1yich Tchaikowsky, but all of them turn
o" t to be hi-Ii men for abo ut the s ame reason·their use of a big orchestra and lots of orchestral
color-stuff and power-s tuff.
Of these two the earlier, number 2, is the most
potent for hi-fi as well as the m ost dissonant. I
once sat in the midst of a live orchestra rehearsing
·this piece and I shall decided ly never forget it~uch brass and percussion you can scarcely imagme! The first movement is all-brass-percussion
·the second all-strings, the third- the works_
'
This is the first recOl'ding to approximate the
·overpowering potency of sound that the live work
conta ins and the louder you play it the more
true it will be to the _original. Not exactly an
·electric performance in the over-all and I've heard
better; but the stunning close-up record ing easily
m a kes up for this defic iency.
The Th ird Concerto, a later and much more
grateful (but not as exciting) work, is similarly
;miked and very nicely played, better, I'd say, than
-the Second. Hi-fi miking really suits this music
;musically.
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The C350 , t o g e t her with t he Cr aftsmen C375 filter syst em,
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DECEMBER, 19,54
Chicago 40, III .
41
www.americanradiohistory.com
AmericanRadioHistory.Com
men. It seems to me that Cook has found
a useful ill-between recording area not
quite mere sound-effect stuff ( thougil the
sounds are unusual endugh) yet not quite
a ltogether of purely material interest. It
suits him to a T and he does tIle job well
with imagination, as is proved by the s timu~
lating variety of subjects he has so far
tackled.
that the duplex record gives YOll only half a
record of monaural sound, but th at won't deter
fans who like exotic sou nds-rm one of themfor t h ese are gems.
The calliope plays so gorgeous Iy out of tune
that if you're a good musician you can only gasp
w ith pleasurable angu ish, especially in " J eannie
with the Light Brown Hair" and an excerpt from
"Carmen." The C arouse l is somewhat less rau cous-its bass is bizarrely out of order-but it,
too, has a ghoulish mechanical robot quality that
can hardly do less than titillate the trained ear!
Conversely, the Marimba recording (23·foot
jobs) features some of the most musical p laying
I've ever heard, though outwardly the instru·
ments aren't too far removed from the carousel
in tone quality. Just shows what the human
touch does for music.
* Calliope and Carousel.
Cook 5010hn
• Marimba Band. (otherwise known as ...
to Hell with High Fidelity.) Cook 5007 0n
These two super-hi-fi jobs are "duplex" records
which is a euphemism for "binaural" - that is'
you can play only the outside band on a standartl
single pickup; the inner half is for "binaural"
sound with a second pickup. It isn't mentioned
Tiroro (best drummer in Haiti
.).
Cook 5004.
YOU .CAN OWN THE HIGHEST QUALITY
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A one-man fiend of a drummer, who sings too
now and t hen. Not exactly hi·fi but the drum·
ming is very well recorded. Informal·style with
bits of interview, odds and ends of back~round
nOlse, etc.
American Storytellers vol. 3 (Of Whaling
and Shipwreck) .
Cook 5009.
(This is the only one of this series I've played
so far.) Two old gents, a fisherman and a very
elderly (89) whaling man, are interviewed, drawn
out, about their seafaring past. Pretty disorganized
and it takes a good while to pump up real interest
in t h e "stories," but if you have patience the
records are well wOl-thwhile. Interesting accents,
ways of speech.
These are not rea l story tellers, in the folk·tale
trad ition. They are simp ly men recalling their
adventuresome pasts. We have not yet heard from
the story . tellers themselves, the ones who ten
stories, not those who write them down.
(The Cook "Road Recordings," semi-informal
tapings, are limited-edition discs, non ·returnable.
Better get the detailed catalogue, before you buy.
Cook Lab., 101 Second S t ., Stamford, Conn.)
"'d Christmas Carols on the Organ. Virgi~
Fox.
RCA Victor LM 1845.
",r, Christmas In High Fidelity. George
Melachrino & arch. ; RCA Victor LM 1045
Got to hand it to RCA for coming up very fast
in pure hi-fi sound technique. I approached the
organ item above with unmixed diffidence, being
an old anti-Xmas carol-on-the-organ man, but
I'll have to admit that it sounds remarkably good,
the arrangements, bells and all, aren't bad, and'
the organ itself is superb, and beautifully recorded.
(Aeolian-Skinner, Riverside Church, N. Y .) Oneof the best and most natural big·organ record·
ings I've heard.
When RCA's people get hold of a thing they
surely plug away relentlessly. Now it's Xmas it>
High Fidelity, with the expected cascades of
jingle·bells . triangles, brass and all the rest. But
-again I'll admit g lad ly-the recorded sound is
penectly gOl'geous, and I am thankful for RCA's
big-liveness, mellow effect, where so many hi-fi
records are close as a closet and as edgy and r aw
as-well, a steam .calliope. (See above.)
I enjoyed sever-al of these Melachrino pot·
pourris of mixed Xmas music in a semi-pops
vein. Sixteen, though, is too much for me. You
try 'em.
':'C Rimsky-Korsakoff: Capriccio Espagnol.
Tchaikowsky: Capriccio Italien. London
Symphony, Scherchen . Westminister Laboratory Series W-Lab 7002.
MOTEK TRANSPORT MECHANISM
Driven by three individual AC motors.
Speed 7% I .P.S., dual tracks.
All electrical push button switching and
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Hi-Fi r ecord/playback and erase heads.
Frequency response better than SO - 10,000
C.P.S.
WOW and FLUTTER less than :3%
Accommodates 7" reels (1200').
]in.tone
•
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.. Separate power pack for remote installation
to a void HUM.
• Record frequency 'range 50 - 10 000 C.P.S.
Erase .and 'Bias frequency 45 kc/s.
• Controls record. play-back a~d amplifier selector switch, tone, volume, phono,
maste r volume.
• 'Input - for m icrophone, phono, radio and
telephone pick-up with provision 'for mix.. ,
jng, ' also, input for feeding into your'
present amplifier.
preset tone compe nsation on record, to
provide correct equalization.
• . MOllitoring Magic Eye R ecord IndicatOf, .witp. provision , for ' he~dphone· moni ..
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The only truly automatic. and foolproof
changer (patented), pla'y ing ten inte rmixed ,r e'cords, 'without pre-setting, in.
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AutoDlatic muting switch4 Automatic shut:.
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'
'Price include; . famous PEB . dual cartridge
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You can play PE R ex independently wi~h·
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+
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FENTON COMPANY
lS."MOORE STREET
•
NEW YORK 4, N. Y.
46
For long weeks after the Audio Fair I could
not bring myself to open the all-plastic zipper
bag that contains this special high·quality labo·
ratory-standard disc, because of the incredibletreatment it received in umpteen dozen rooms at
the Fair where it was b las ted forth at hideous.
horrible, ear-rending, searing, painful h igh volumes. Does hi·fi have to be boiler-factory style?
But, at last, I've just played it through in
my own living room-at a plea.s ingly low, sweet,
lovely, lyrical, velvety·soft level-loud enough
merely to drown out my speaking voice and certainly a bit louder than I have h eard the samesounds from a good balcony seat in Carnegie Hall.
Delightful! This is the real thing.
There are serious points made here, though
my own musical tolerJ nce for capriccios, Italien
or Espagnol, was exhausted long before hi·fi was
thought of. For good sales, the record is dolled
up with a very fancy packaging, hut it represents
a new and quite legitimate attempt to reach ultra·
high standards of d.isc processing, incidentally
setting standards for future "ordinary" releases
to a im at, and in this it is akin to the special
auto models lately popular, those research experiments that are sold to the public as, in a
sense, a part of the research itself.
The basic claims are for very low disc distort ion of a ll sorts (in addition to top· quality recording and miking to begin with), particularly in
respect to the "echo" effect · of groove deformation that prints a loud passage faintly through
close groove walls. Such distortion is eliminated
here by wider groove spacing, and a generous
center space a llowance removes the distortions
that come from grooves cut too near the centera ll of this, of course, at a sacrifice of exterme long
play. (15- 16 mins. per side).
On the basis of listening, I'd say Westmil1ster
proves its claims handily. Above all other im·
AUDIO
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AmericanRadioHistory.Com
•
DECEMBER, 1954
·e'}
ILOTUNER
"
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tubes including Rectifler. Cathode Follower
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The Ultimate h; engineering skill · ciri~;t~.'lIilivilty
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AUDIO
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DECEMBER, 1954
45
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AmericanRadioHistory.Com
EDWARD TATNALL CANBY*
The Hi-Fi Horrors
B
I REVIEW a single hi-fi record
more I've got to stop and blow off a
bit of strictly low-fi steam about the
current craze for high fidelity on discs. To
whit: I'm thoroughly and completely tired
flf it.
That's personal, I admit. I've been a
champion for good recording since 'way
back and I'm one of those musicians who
hails the recorded medium as a mature and
important thing in itself-I'll jump quickly
into any argument which suggests that records are a mere substitute for the "real
thing" and I'll insist that a recording is
the real thing, in one of its alternative
torms. I will never look down on recordings, or on the business of recording, or on
the engineering of records, as something
beneath the true artist's consideration I But
f'm still sick of hi-fi records.
r feel strongly that the sound of recorded
music, moreover, has its own special
aesthetic-acoustic laws. I do not believe, as
many do, that the ultimate aim of hi-fi is
to re-create an illusion of the concert hall.
[ will stand up vehemently for all experiments and all developments in hi-fi recording technique .that explore these special
laws, for all engineering tricks, hi-fi or
otherwise, that bring better sense and
clarity and beauty to the recorded material
-whether it sounds like a concert hall or
not. Mostly it won't and I'll love it. But
['m still sick of hi-fi records. My ears are
~ore with them.
[ am delighted, for example, at the new
tt!chniques for recording opera that bring
the singers up close and loud, in a big, live
background, surrounded by the orchestral
sound. No "live" opera ever sounded remotely like this, by the wildest stretch of
imagination. But on records (and via broadcast) a vast range of operatic music has
now been effectively projected, straight
from the music to the listener, by these new
recording methods. Opera on records is a
vast success in terms of sheer direct communication and there isn't an opera recording in a carload that has an operahouse sound.
So, too, with many a concerto, many a
symphony, many a string quartet, lieder
recital; all of these can benefit ~y the spe"FORE
cial tricks of microphoning that have been
worked out exclusively and deliberately for
listening via the loudspeaker. Without
these new hi-fi techniques (and the hi-fi
engineering that necessarily goes with them
all along the line) we would miss a vast
range of listening pleasure, musical and
otherwise. Without special recording techniques, records really would be a poor
substitute for the omnipotent original.
KEY
• Outstanding recorded sound
for the type of materia I.
Unusually fine performance.
bb Bass end is rather thin.
bn "Binaural," for two pickups.
C Close-to, sharp-edged. but in
big liveness.
d Distant, over-all miking; good
liveness.
EI Extreme
"hi-fi"
technique;
played-up drums, triangles,
ultra-close pickuJ) in big liveness.
I Intimate, close-to recording in
good liveness.
I Limiter (monitor) action: dynamic range restricted.
L Big, blown-up liveness.
• Solo part close-up and loud .
•• Accompaniment is· in background.
x Distortion in louder passages.
[ndeed, it is recording know-how, recording technique, that makes a record not a
mere substitute but a power in itself with
its own values. Hi-fi recording? It is recording-good recording.
But I still don't like hi-fi records and
I'll tell you why.
1. Because recording technique is a
means to an end, which is the most effective projecting of the material on the record. The hi-fi records that I don't like are
the ones that-intentionally or not-reverse
this principle. They don't project the material, they project the recording technique.
It's not merely the cart before the horse;
it's the catsup without the hamburger, the
shaving crt!am without the whiskers; OJ
more to the point, alas, it's the sound with
out the music.
2. Because recording technique is a
means to an end, which is the most effec
tive proj ecting of the material on the ree
ord-and many of the new hi-fi records dl o
serious damage to the sense of that mate·
rial. Over-playing the engineering hand
may fascinate the fanatics but it does a lot
of harm to recording itself, for it puts the
entire field of recording into bad repute
with those who love music. It obscures thr
plain fact that good hi-fi recording tech·
nique is good for music.
3. Because recording technique is ~
means to an end, which is the most effec·
tive projecting of the material on the rec·
ord, and much of the material itself on
recent hi-fi records is dull, repetitiou~ .
stupid, in bad taste, raucously over-orches·
trated; many of the most sensational records bring us the same old war-horse piece~
of music we've been hearing already for
too many years. They are still dull whether
hi-fi or low-fi, for some ears. No amounl
of technical ingenuity can make them ap·
preciably more interesting. (Though some·
times an unusually good musical performance can bring them back to life.) This.
take it from me. is the music lover's view
point.
A good hi-fi record, I always say (and
will say again and again . . .), combine~
good material, good performance and opti·
mum recording technique for the material
It is the over-all balance that counts.
With that said. let's look at some hi-Ii
records.
Cook's Tour
Emory Cook has found his metier. Or
his latest metier, anyhow. D- it, he's
scooped me on at least two pet projects of
mine that I've never had a chance to play
around with and he's found plenty more, as
well, for his roving tape recorder. The
Sounds of Our Times records, at first plain
hi-fi sound-effects, have gradually spread
out into wider fields of interest-content,
material-and now, with the new "Road
Recordings" (on-the-spot jobs) we have
everything from calliopes to pedal harpsichords, Haitian drums to whale fisher-
AUDIO
44
www.americanradiohistory.com
AmericanRadioHistory.Com
•
DECEMBER, 1954
More Disc
;, R,~cordings '
Are Made TodaV
.•• THAN
EYER
BEFORE!
Fig. 8. Turntable drive mechanism and the
pickup arm follow high-quality phollo design.
a selector button for the record of his
choice, some indication of his having
expended a portion of his credit must be
given him. As the customer deposits his
money, then depresses the selector buttons one by one, a credit take-off knocker
gives a good audible knock each time,
so there is no doubt that the record has
been selected and that one less credit is
available. In these instruments, the
credit mechanism normally gives one
play for five cents, two plays for ten
cents, and five plays for a quarter. However, the operator can change the crediting so that the instrument will give six
plays for a quarter, if that is the prevailing custom in a community; or for highclass patronage, the machine may be adjusted to give one play for ten cents and
either three or four plays for a quarter.
The slug rej ector is. a necessitypeople bei ng people-and the locked cash
box is desirable. All the components of
the mechanism are connected by means
of plu'g s and receptacles so as to eliminate trailing wires as the individual
parts are removed for servicing.
The mechanism is thoroughly proven
in years of service. Screw adjustments
permit setting the stopping switches for
accurate record selection, and when
power is restored after a temporary
fail ure, the mechanism will not jam, but
will continue its cycling. Placement of
contacts and relays eliminates the possibility of dust or grease causing erratic
AAeration, and the entire instrument is
iii:~(ctically foolproof.
Conclusian
. AMI's new Model F juke boxes signal the end of an era of poor sound in
coin-operated music machines. Combining a high-quality pickup and amplifier
with a two-way speaker system so placed
as to overcome the disadvantages of
many locations in which these instruments are required to work will serve
to raise the public acceptarice of these
instruments. One need only hear one of
these new models to be convinced that
high fidelity has come to the juke box.
AUDIO
•
the
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REK.O.K~
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PRO FE S S ION A L 0 I S C R E COR 0 E R
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and
The outstanding advantage of a permanent disc recording is that it
can be played on any phonograph. Most tapes, in fact, ultimately end up
on discs.
Naturally, the quality of the results greatly depends upon the quality
of the equipment used. The Rek-O-Kul Challenger is the only portable disc
recorder designed expressly for professional recordists, musicians, educators, and recording enthusiasts, who desire the kind of quality normally
associated with costly professional installations. The Rek-O-Kut Challenger
is, in fact, the only portable, 12-inch recorder capable of handling professional 13 %" masters.
Every feature has been embodied 10 assure the highest quality of
recorded sound. It is the only portable, 12-inch recorder driven by a constant speed, hysteresis synchronou~ motor. This means recordings with virtually no noise, wow, or flutter. Moreover, it is the only portable recorder
with a professional overhead recording lathe and with interchangeable
leadscrews for standard as well as microgroove recordings, whether at 78
or 33% rpm (an accessory idler is available for 45 rpm).
The Challenger amplifier was designed for the utmost fidelity. It has
a frequency resp~nse ± 1 db from 30 to 20,000 cycles, with independent
equalizer controls for bass and treble response. Recordings can be made
from microphones, from radio tuners, tape recorders, and other signal
sources. Recording level is visually indicated by means of a meter.
For playback,the Challenger is a complete high fidelity phonograph
with dual-stylus magnetic pickup, and a wide range 10-inch PM loud.
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Rek-O-Kut Challenger for 78 and 33% rpm, with Standard
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DECEMBER, 1954
43
www.americanradiohistory.com
AmericanRadioHistory.Com
I- RESPONSE
EQUALIZATION
RANGE
+l0
+1 0
~
-
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.co
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RONETTE TO-284P
PICKUP CARTRIDCE
OF AMPL. FOR SPEAKER :-
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Interest in phonograph pickups has never
~0 ~H-H±~.~~~~~~~~~~~~~r-~
abated, and with the introduction of each.
-10
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new one there is speculation as to the performance and its various characteristics.
~=t-i"*l'l1~""',j ~~:-~~~OUENCY
-20
CURVE
RIAA
Tests recently made with the Ronette
FREQUENCY
TO-284P crystal cartridge indicate that it
OROOP
would serve well for high-quality phono
,.
eycus
reproduction, and to all indications this
unit seems to offer some definite advantages.
Fig. 8. Performance curves f.or the Ronette
The cartridge has relatively low output
TO-284P crystal cartridge.
for a crystal-using the Dubbings D-100
test record the measured output with a
corded with 100 and 7000 cps and at . two
I-megohm load on the 3000-cps band is 80 different levels. This was to be expected,
my-but the other characteristics of the considering the exceptionally "clean" quality
pickup more than make up for this. When
of reproduction on listening tests. No measworking into a lo~d of I megohn, the
urements were made on th~ 78-rpm side
frequency response of the pickup from the of the cartridge, but it is to be expected
test bands of the D-IOO test record show that the performance would be equivalent.
a response which is down 4 db at 30 cps,
The construction of the cartridge is such
and fiat within ± 1 db from 1000 to 5000
that the idle stylus is not actuated by the
cps, and with a gradual rolloff from 5000
playing stylus, and consequently does not
to 10,000 cps of 5 db. Thus, when working
introduce the usual dip in the response
into a fiat amplifier, this pickup would re- curve which is the result of the resonance
produce the RIAA curve correctly with a of the free stylus waving in the air.
roll off of approximately 8 db at 10,000 cps
The cartridge can be mounted in any
and a boost of 3 db at SO cps- both of which desired arm. Styli are readily changeable,
would 'be easy to obtain with typical tone and the pickup is neat and attractive in
control circuits.
appearance. The arm and cartridge track
If the cartridge is worked into a load
the four lowest-level tracking-test grooves
of 0.12 megs, the low-frequency curve folof the Dubbings record with a stylus force
lows almost exactly the bass-boost charac- of 6 grams; an increase to 7 grams is reteristic of the RIAA curve, and the perquired' for perfect tracking on the "+ 15"
formance above 1000 cps remains the same band, which corresponds to a stylus velocity
as with the higher load. This means that
of over 25 cm/sec. Thus fo r almost any
the cartridge performs almost exactly as a 'LP record, satisfactory tracking would reconstant-velocity device, and would work sult from a stylus force of 6 grams.
correctly with most preamplifiers if the
Since the Ronette cartridge is a crystal,
input resistor were chanped to 0.12 megs.
it is not susceptible to hum pickup from
Curves of these measurements are shown in magnetic fields-an advantage when used
Fig. 8. The dashed line is the response into
with some of the lower-priced turntables
a I-meg load; the dot-dash line is the rewhich have this trouble. This would make
sponse into a 0.12-meg load; and the dotted it especially suitable for use with the small
line is the response when feeding into a 0.5
45-rpm changers, which are infamous for
meg load. The solid line is the RIAA char- their strong hum 'field.
acteristic-drawn so as to permit direct
In direct listening comparison, this pickup
comparison. Thus it is seen that the low- proves that it is not necessary for a crystal
frequency performance can be controlled pickup to have the typical "crystal" sound
quite readily by choice of the load resistor. often referred to by Mr. Canby in his
AUDIO ETC column, and it is probable
The Cook inter modulation test record
that most listeners would comment on the
shows no measurable distortion on either
"clean" reproduction obtained.
of the two bands, both of which were reHIGH~
-10
-lO
"UQUIlNCV IN
.
..
...
-
. ..
. ..
I'lIEOUIlHCY IN eYCUS Nft SI:(;OHO
I
-
.
.
I
I
I
I
AMPEX
:
620
I-
I
I
0
. :
00
r
.
-
.
-
/'
"
POWER OUTPUT
.0
~
WATTS
Fig. 7. Performance curves for the Ampex 620.
bend. Below 10 watts, the 1M distortion is
less than 2.5 per cent, reaching 1 per cent
at the 2-watt level, which is more than
sufficient level for the built7in speaker. This
distortion is considered low for an ampli fier
using 6V6's.
On listening tests, it was noted that
constancy of acoustic output was apparent
from 60 to 12,000 cps at normal levels. As
the volume was increased, the speaker
seemed to "breathe" at the lower frequencies, the point at which the breathing
started increasing in frequency as the level
was raised. For normally usable levels,
however, acoustic output was comparable
to may larger speakers, and the whole idea
of compensating the amplifier to match the
speaker seems to work out to provide an
exceptionally successful unit.
The 620 is housed in a Samsonite case
which matches in size and appearance the
Model 600 recorder, which was reported
here in the July issue.
JUKE BOX
(from page 38)
groove records wi ll reproduce quite
satisfactoril;, with one equali zation
curve.
How well the amplifier and speaker
system live up to the claims made for
them can only be determined by listening
to the instrument with high-quality records. There is no boominess, but a full
rich bass, and the treble response is
equal to that in any properly adjusted
home system.
Phonograph Equipment
No amplifier and speaker system can
perform properly unless the signal fed
into it is of good quality. Standard GE
variable reluctance pickups are use in
these instruments, being mounted in a
cast aluminum tone arm pivoted on
needle bearings. The turntable drive
mechanism and the pickup arm are
shown in Fig. 8, and it will be observed
that the type of drive is similar to the
best of the turntables in home systems.
In fact, the bearing surfaces are considerably larger and better finished than
the average to ensure long life and
reproduction free from wow and flutter.
The conical center spindle provides easy
location of the record from the lifter
Changer Mechanism
Fig~tre 7 shows the changer mechanism. The turntable chassis moves longitudinally along the record rack, being
stopped at the desired record by magnetactuated selector fingers. The drive
mechanism for the turntable chassis
consists of a roller chain which is driven
by the silent gear motor. As the turntable stops adjacent to the selected record, the gripper bow picks the record
out of the rack, lifts it up, turns it to the
horizontal position, and places it gently
on the turntable-the direction of the
turn being dependent upon which direction the carriage was moving. After the
record is played, the gripper bow lifts
it off the turntable, rotates it to the
vertical position, and places it back in
the rack, after wh ich the carriage moves
to the next position and the operation
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AmericanRadioHistory.Com
_II SCCOt.IO
,-
arms, and the heavy cast turntable is
felt padded with the record supported-'
and consequently driven-at the rim to
eliminate slippage vibration, and chatter.
Tire pickup arm lifts up to a vertical
position to faci litate cleaning or stylus
changing .
repeats. Like all record changers, the
entire action looks like a Rube Goldberg, but the same type of mechanism
has been in 'use dependably for years.
A n indicator on the carriage shows the
number of the record being played, and
under the indicator plate is a popularity
counter which shows how many times
each record in the rack has been played.
This is not visible to the customer, but
is of considerable value to the operator.
The Business Department
The important aspect of any coinoperated machine is the ability to accept
the money, reject slugs, tally the receipts
accurately, and, allot the correct amount
of "merchandise" to the customer. In
the case of the coin-operated phonograph, this merchandise is a given number of plays and as the customer depresses
. . AUDIO
42
-
•
DECEMB~R.
1954
Thi8 photograph 8Ughay more than :If., actual 8ize.
A Little Fellow with a 15 Watt Wallop
BOGEN DBISG AMPLIFIER
Now you can own custom audio components which combine
superb quality with a mechanical design so compact that
they provide the solution to almost any installation problem.
This DB15 amplifier, for instance, gives you a full 15 watts
with distortion of less than 0.5 % at full power. As for flexibility: the DB15 features a two-section record equalizer
allowing a choice of 20 combinations of low frequency compensation and high-frequency roll-off, separate continuouslyvariable tone controls, exclusive Bogen Loudness Contour
Selector, separate equalized inputs, and tape recorder output
jack. DBl5G-Amplifier in Handsome Cage. Only 18 lh" x
9" x 6%,". No installation problems. $99.00. DBI5-Same
unit without cage. 12 l ,i" x 8%" x 8%,". $89.95.
BOGEN R640G FM-AM TUNER
Perfect companion for highperformance amplifiers, this
tuner is especially designed to
avoid duplication of controls
and to fit neatly into close
quarters. Features high sensitivity (5 microvolts), high
selectivity, negligible distortion and flat frequency response (within 1 db from 50 to 15,000 cycles on FM). A
special, controllable AFC circuit prevents drift and simplifies tuning. R640G-Tuner in Cage. Matohes DB15G. Only
18%" x 9" x 61,i". $112.95. R640-Same tuner without cage.
The ideal mate for DB20, DB15 or DB10A amplifiers when
installed in cabinetry. 18%," x 7%," x 5%". $105.50.
BOGEN DB I OA AMPLIFIER
Here's Bogen's famous
DB10A, priced to fit any
budget. This compact marvel
of tone delivers 10 watts of
power at less than 3% distortion and has a flat frequency
response (plus or minus 1 db)
from 30 to 18,000 cycles. In addition to a built-in phono preamplifier, the DBI0A features a special tape recorder output
jack and a 3-position equalizer for LP, 78, and Pop. $54.45.
Note: All prices slightly higher in the West.
SECOND PRINTING:
"Understanding High Fidelity" is fast becoming a standard manual of hi-fi theory and application. Clearly and concisely. this new enlarged
56 page edition presents invaluable practical
information to help yOU get more out of any
sound system. Send 25¢ for your copy.
BOGEN DB20 AMPLIFIER
The magnificent DB20 is rated
the "Best Overall Quality" by
a leading consumer organization as well as by thousands
of audiophiles all over the
world. The DB20 combines 20
l..l. S~="" watts of undistorted power
with remarkable flexibility of
control. Even at full rated
output distortion is only 0.3 % ! Other features include the
exclusive 5-position Loudness Contour Selector, a 10-position
input selector-phono-equalizer, output jack for tape recorders, and extremely effective non-resonant separate tone
controls. $99.00.
DB20DF. The DB20 is now available with the new exclusive Bogen Variable Damping Factor. This built-in control
provides cleaner bass response by reducing speaker distortion and "tuning out" resonant peaks. $108.00.
AUDIO
•
SOUNDS BETTER
- -David
- - ---Bogen
- - ---BECAUSE
--- -- -IT----- --- ---- --- --- ----Co.. Inc.
Dept. VL
29 Ninth Ave.. New York 14. N. Y.
Send "Unde1'standing High Fidelity" (25¢ enclosed) and
free catalog.
Narne' ____________________________
~-----------
Address _______________________________________
City
o
Zon<>-State'___________
Send free catalog only.
DECEMBER, 1954
41
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V-M MODEL 700'TAPE-O-MATIC
TAPE RECORDER
Reporting on the performance of tape
recorders for high-quality home music
installations becomes rather difficult when
the type of equalization employed in the
I\1strument does not make it possible to
acc~mmodat~ standard tapes satisfactorily.
While practically any of the machines on
the market provide reasonably good fidelity
from microphone or tuner input to tape
output, relatively few of them provide the
type of equalization that permits playing
,tandard professional-type tapes with a
;atisfactory response. For this reas-on: we
~ave used the Ampex Alignment Tape No.
)563 as a standard, since any machine which
will play this tape satisfactorily will play
most (pre) recorded tapes in a manner
that will be pleasing to the user.
The V-M Tape-O-Matic Model 700 has
equalization controls which can be adjusted
to reproduce the Ampex tape within ± 3 db
of flat from 50 to 8000 cps, which is adequate in our opinion. Response from radio
input to playback out is slightly better than
this on the high end, and about the same
on the low end at optimum adjustment of
the controls.
T his recorder has several features which
make it attractive to the serious user. It
is the only non-professional machine we
have observed so far that has a stop switch
which turns off the mechanism I when the
tape runs out or breaks. Furthermore. it
is equipped with a PAUSE control, which
,tops the tape without disengaging the
drive mechanism, a feature that is desirable
1\1 transcribing or for specialized types of
recording. A separate switch permits monitoring the incoming signal during recording
-either from radio or phono or microphone
-and this, too, is unusual on home-type
machines.
Figure 5 shows the response curves from
the Ampex tape, with the range covered
by the tone controls shaded. For those who
wish to "dub" from phonograph records,
the built-in preamplifier provides equalization which is quite close to the RIAA curve
when a slight amount of high-frequency
boost is added. Full recording level is
obtained at maximum volume control setting with an input of only .0003 volts from
the pickup and from only .0013 volts at the
AMPEX MODEL 620
AMPLIFI ER-SPEAKER
This is a rather surprising little "box
of tricks," for one familiar with audio
equipment is likely to be skeptical of a
loudspeaker mounted in a cabinet about
one half cubic foot in content. But the
specifications claim that the unit as a whole
gives an acoustic output which is essentially
flat and free from dips and peaks from 65
to 10,000 cps, and performance lives up to
the specs quite well. The loudspeaker mechanism is a heavy-duty 8-in. model with an
unusually large magnet assembly mounted
on a cast frame. It is enclosed in a compartment about 12 in. square by 5 in. deep,
with rock wool acoustic treatment inside.
The over-all dimensions of the entire unit
are 13 x 16 x 8 in., which includes the
amplifier.
The trick- if we may call it that-in
obtaining good low- and high-frequency
performance from such a small enclosure
lies in equalizing the amplifier to complement the na.t ural characteristic of the
speaker and enclosure. This is done in the
feedback circuit when the built-in loudspeaker is being used, but when an external
Fig. 4. The V-M
Tape-O-Matic tape
recorder, with builtin two-way speaker
5Y5t!;!m
radio invul. 1M distortion at full recording
level is approximately 6 per cent from input
to playback, reducing to 4 per cent at 15
db below maximum level. This is satisfactory for home use, 'since most professional
machines will measure from 2 to 3 per cent
through record and playback amplifiers
and the tape. Fast forward measures 125
seconds for a 1200-foot reel, with rewind
at 95 seconds. T he bias frequency is approximately 70 kc.
The machine is attractively housed, and
offers a two-way speaker built into the
cabinet, with audible response down to 60
cps, and up to over 10,000 cps. Low-frequencies are apparently increased by the use
of a circuit known as "syntheti!; bass," an
arrangement which provides some positive
feedback from the output-stage cathode to
the driver cathode.
The keyboard operating controls are easy
to use, and with the pause control provide
complete facility of operation. A very precise tape index counter is provided which
permits locating any previously recorded
selections with accuracy. On the whole,
this machine would be a convenient addition
to the home system where portability and
ease of operation are important.
I---'I+H-f+tl-- b PHONOGRAPH
EQUALIZ~~I~~I
I--
+201~~~.~~}-/~~~~}-~4-~~r-~
1"",-:-.HI+H+m--H~H+m---j
+10Hl+lffm..
'.
""IOUII:NC'f IN
,-
eyc u s
~
SECOND
I I
I 11111111
RESPONSE FROM -RADIO-
+20
IN TO PLAYBACK
out
+1 0
-1 0
,
-20
.
. .. ,.
. .. ,e .. e ....
I'1I1001"'ICV 'N
I"Cft HCONO
. ..
-
Fig. 5. Performance of t he V-M Model 700.
speaker is plugged in, the equalizing network is replaced by a flat network- a resistor- which makes the amplifier flat
within less than 1 db from 20 to 20,000
cps. However, when used with the internal
speaker, the response of the ampl ifier-with
the equalizing control set at 0 or flat-is
modified to that of the dotted curve in
Fig. 7.
-~-he";'amplifier
consists of three stages:
a 5879, which is preceded by the volume
and equalization controls, a 12AU7 "Iongtailed pair" phase inverter and driver which
is direct connected to the plate of the
5879, and a pair of 6V6's in push pull.
F eedback is returned to the cathode of
the first stage. I-watt output is obtained
from an input of 0.22 volts at the flat setting of the equalization control, with about
4 db less input being required at either
maximum of the equalization control. This
latter is not comparable to a tone control,
for it has an over-all range only 11 db on
the low 'end and about 7 db on the high end,
and should be used only for minor corrections to suit acoustic conditions. The amplifier has a rated output of 10 watts, but
delivers up to 13 watts before the 1M distortion curve reaches its sharp upward
40
Fig. 6. The Ampex Model 620 AmplifierSpeaker unit in its Samsonite portable ca rrying
case. The cove r houses th e connecting cords.
AUDIO
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•
DECEMBER, 1954
1M'i,-+-1I-+I-H
II-Il-II-+PHO~ EQUAlIZATION
+201""1
Equipment Report
r--
-EUR
leAR
n
-to
"'-,
RIAA
Craftsmen C350 Equalizer-Preamplifier-V-M Model 700 Tape-O.
Matic Recorder-Ampex Model 620 Amplifier-Speaker-Ronette
TO-284P ·Pickup Cartridge.
r;-H~~~-+-+-1+H~~-+-+-1+H~~~
ROVIDING a complete centralized control
unit sufficiently flexible enough to
meet the most demanding require- .
ments, and with features which give the
user an exact knowledge of what he ;s
doing, the Craftsmen Model C350 equalizerpreamplifier is one of the newest to enter
the market_ This unit is housed in a metal
cabinet 3-7/32 in. high, 12-1/2 in. long,
and ·7 1/32 in. dee,[>, and is self powered,
drawing approximately 21 watts from the
117-volt line. The circuit consists of a
2-729· low-noise- pentode as the preamplifier
stage, connected as a triode, followed by
a 12AX7 with the equalization furnished
by feedback around the first section, and
with the second section serving as a cathode
follower to drive the first section of the
volume control-which is designed to serve
as a loudness control when the compensating networks are switched into the circuit.
(The second section of the volume control
is in the grid circuit of the cathode follower
output stage so as to reduce hum to a
minimum for low-level reproduction). The
first section feeds the one half of another
12AX7, which in turn drives the treble
P
+l0r;-H+H-H--+ TONE~TROL t-I-+tttttt--i
P'''IOUlDICl' ,,. c"t"CUS P'DII "COHO
~
~ • -
~;4
-
I
I
CRAFTSMEN
C350
gl
/
~i3 t---+---/----l--+---J,...-~
g7
I
~
t~H-moo:::::....-::::r. .;::;;-""tV"-I~
.
I ,·I:+tH'-t-H-:b-,H"-f--+----if--+--I
~ °L.J....U..
I-'-t· I. . I- ~J. .-.I:':~+--!----+--!
0
~
4
OUTPUT - VOLTS
Fig. 1 (above) . Performance curves for
the Craftsmen C350.
Fig. 2 (left). External
appearance. Fig. 3
( below). Over-all
schematic.
AUDIO
•
DECEMBER, 1954
tone control, while the second half drives
the bass tone control. The two sections of
the third 12AX7 serve as a voltage amplifier and the cathode-follower output stage,
respectively, and provide a nominal output
of 1.5 volts.
Seven separate equalization curves are
available on the selector switch, with individual level-setting controls on each of
the four inputS-TAPE, TV, TU NER, and
PHONO. An output for feeding a tape recorder appears at the cathode of the first
12AX7, just ahead of the volume control,
and at a l.5-volt output provides a signal
of 0.28 volts.
The equalization is based on a fixed droop
of 4 db at 10,000 cps, which is introduced
by selection of the proper load' resistor at
the input. Thus when measuring this amplifier, the curves will not appear to match
those in the instruction sheet unless allowance is made for this difference. With suitable load resistors for the pickup, however,
the curves match the specified characteristics quite closely, as shown in Fig. l.
Figure 1 also shows the range of the
tone controls, as well as the e.ffect of the
loudness compensation at 20 and 40 db
below maximum settings of the control.
Intermodulation distortion measured from
the tuner input to the output is less than
1 per cent at the nominal output, and
reaches only 4 per cent at four times the
rated output. With the average power amplifier, distortion i's likely to be less than
0.1 per cent at operating levels.
The two tone control circuits are somewhat different from the usual type, as will
be noted from the schematic, Fig. 3. The
boost end of both controls are driven
directly from the plate, while the taps on
the controls are driven from a voltage
divider in the plate-load circuit. This permits shaping the curves more carefully,
and in listening tests the controls provide
good musical quality.
The power supply is fairly conventional,
although the use of a neon indicator light
is unusual and practical, since it shows
that the equipment is ready to operate,
rather than just that it is "on." In the
off position, a bleeder resistor discharges
the plate supply filter capacitors, extinguishing the pilot light immediately. Two
unfused power receptacles are provided,
but the unit itself is fused. A hum adjusting
potentiometer is connected across the heater
supply, and heaters are biased positively
by 55 volts.
For rated output, l.5 volts, an input signal of .0072 volts is required at the phono
jack, and of 0.26 ' volts at TUNER, TV, and
TAPE inputs. Hum and noise measure approximately 60 db below rated output at
the maximum volume, on the phono positions, with tone controls flat; at the highlevel inputs, hum and noise measure 73 db
below rated output with normal settings of
the volume control for average use, the hum
and noise measure 20 to 25 db less than
these figures.
Construction is readily accessible, with
low-noise resistors being used in critical
circuits. Extreme low-frequency response
can be reduced if turntable rumble is objectionable-simply by removing the short
. from across eG
o.
39
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PROFESSIONAL
DIRE C:::TORY
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RY 1-8171
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to Completed Cu stom Audio Equipment
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February 10-11-12, -1955
The West's leading audio show
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AUDIO
•
Satie once wrote down a report on "A Day
in the L ife of a Musician" whi ch is worth
quoting :
"An artist must regulate his life.
"H ere is a tim e-table of my daily acts.
I ri se at 7: 18 ; am inspired fro m 10 : 23 to
to 11 ;,47. I lunch at 12: 11 and leave the
table at 12: 14. A healthy r ide on horseback round my domain follows from 1: 19
p.m. to 2 : 53 p.m. A nother bout of inspiration from 3: 12 to 4 : 07 p.m. F rom 5 to
6: 47 p.m. va rious occupations (fencing.
immobility, visits, contemplation, dexterity.
natation, etc.)
"Dinner is' served at 7 : 16 and fini shed
at 7 : 20 p.m. From 8: 09 to 9: 59 p.m.
symphonic readings (out loud ). I go to
bed regularly at 10: 37 p.m. Once a week
(on Tuesdays) r awake with a sta rt at
3 : 14 a.m."
Satie's . marginal comments and nonsensical titles have done mllch to spread
the impression that he was a "farceur." a
sort of musical clown, who wrote for the
most part rather innocuous-sounding pieces
in pale, impressionistic hues. The pictu re is
false on both counts. F irst, Satie's titles
represented a musical philosophy whi ch ridiculed the preciousness of so many contempora ry designations. Second, the simplicity of Satie's harmonic and melodic
inspiration was plainly a rejection of the
deliberate vagueness so fondly cultivated
in th e name of impressionism.
Sati e's advanced ideas did not explode
like Bastille D ay fi reworks on the hori zon
of th e Parisian musical world. I n view of
his pe rsonality, that would have been impossible. F or Satie was a gentl e, retiring
sort who abhorred "movements" and preferred the quiet life of a P aris suburb to
the lively atmosphere of the heart of the
city. H e moved from Montmartre to the
dingy banlieue of Arcueil when he was 32
and rema ined there until his death. W hil e in
A rcueil, he devoted much of his time to
the poor children of the quartier and took
part in local community activities. But he
still traveled to Montmartre every day to
see hi s friends. During one of these visi ts
he fell ill and was urged to stay ill town
until he regained his health. H e never r('covered. On July 1st, 1925 the "solita ry old
man of A rcueil" di ed, his body 'na rrowly
avoiding a pauper's grave.
Until r ecently, Satie's music has been
recorded in dribs and drabs, with the notable exceptions of Socrate and Mass for the
Po or (Esoteric) ; Parade and Three Pieces
in the S hape of a P ear ( Columbia) . A t
last, thanks to the imaginative planning of
MGM's Classical A & R head, Edward
Cole, the first LP devoted exclusively to
the piano music of "Ie bon maitre" will be
relea sed in about a month. The pianist is
William Masselos, who did such a fi ne j ob
on Columbia's recording of the Ives Sonata.
By now, it should be clear that, although
there are obvious similarities in approach
between Satie and Berners-each was essentially a " miniaturist" with a piquant
sense of humor-their paths more often
diverged than met. There is no "Satie of
England" (as Berners has been called) fo r
the simple reason that Satie is unique. The
two men, howeve r, have one thing in common : bound up in their small forms is
definitely more than meets the ea r.
20-20
PLUS!
S-226-Q
Output
Transformer
63
DECEMBER, 1954
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RADIO MAGAZINES, INC.
P. O. Box 629, Mineola, N. Y.
Richards W. Cotton, whose impressive
background embraces virtually every
phase of the electronics industry, has
been appointed assistant to the president
of Nationa l Company, Inc.- formerly
served in same capacity for Philco Corporation , .. Arnold Deutschmann has been
elected to newly-created post of execu- tive vice-president and Morris M. Newma n
has been upped to a v ice-presidency of
Radio I'1hack Corporation, Boston. Newm.a.n
will continue his duties as general m an ager. . . . Forrest J. Beard, a newcomer
to the recording field, has been named
assistant advertising manager of the Ampex Corporation.
Eoward G. Eaas, director of advertising
and sales promotion for The Mitchell Manufacturing Company, Chicago, was voted
a vice-presidency at a recent meeting of
the company's board of directors . . .
David A. Remper is the n ew director of
engineering for Stancil-Hoffman Corporation- will handle design of a ll magnetic
recording and reproducing equipment for
the firm; among projects under way is a
new Minltape recorder.
Personnel changes at Fairchild Record- '
ing Equipment Corporation find Bouben E.
Carlson appointed coordinator of hlghfidelity products, C. J. Bachman n amed
theater eq uipm ent products manager,
Robert J. Marshall p r omoted from chief
engineer to head the recently-established
new product development group, and
Frank G. MullI:ns, Jr., joining the company
as manager of engin eering . . . John G.
Frayne i s newly-elected president of the
Society of Motion Picture a nd T elevision
Engineers. Other new officers include:
Barton Xreuzer, execut.i ve vice-president;
Norwood L. Simmons, editorial vice-presiden t ; Byron Roudabush, con vention vicepresident, a nd Edward S. Seeley, secretary.
Regional governors are: Gordon A. Chambers and George Lewin, East Coast area;
Malcolm G. Townsley and W. Wallace
LoZier, Central area, and Lloyd T. Goldsmith and John W. Duval, West Coast
area.
E. Alvin Rich has joined Permofi ux
Corporation as Industrial s a les representative for the New England terri tory . . .
Carroll W. Eoshour, formerly with R a ytheon, has ' been named products m a nager
for Magnecord, Inc. He will b e in charge
of sales engineering, quality con trol, product service, a nd technical sal es promotion
for all divisions of the company.
Newly-added to the sound sales staff of
New York's Hudson R a dio & T elevision
Corpora tion are Robert Ste,i ndler and Edmond Arlessohn. Both were formerly eng a ged as Independent high-fidelity conSUltants . . . Dr. X. C. Black is new head of
Raytheon Manufa cturing Company's communications engineering department . . .
Dr. V. X. Zworykin, tel evision pioneer and
inventor, was g u est of honor at a dinner
given by RCA markin g his r e tirement as
vice-president of RCA Laboratories and
his a ppointment at the first honorary vicepresident in the company's history; Brig.
General David S arnoff was principal
speaker . . . Paul XUpsch, inventor-designer of v a rious corner speaker systems
bearing his name, chose the week followIng the New York Audio Fall' for a press
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•
DECEMBER, 1954
AUDIO 1954
SUBJECT 'I NDEX
Accurate design of phono equalizers;
Charles F. Hempstead and Hamilton
Barhydt. I , Aug, 22; II, Sept, 24.
ACOUSTICS
Sound diffusion in rooms; M. Rettinger.
Aug', 19.
Adventures with a bass reflex; Milton S.
Snitzer. Jan, 26.
Allen orga n, The; Richard H . Dorf. July,
20.
AMPLIFIEUS
Bandwidth ; AUDIOLOGY, Feb, 12.
Control unit for the Williamson, A '
Charles R. Miller. Sept, 19.
Dual-channel control amplifier for
stereophonic systems; Wayne B .
Denny. }Iay, 17.
Juke Box goes hi-fi, The ; C. G. McProud. Dec, 33.
Medium power tetrode amplifier with
stabilized screen supply; Cullen H .
Macpherson. Feb, 30.
New Golden E a r amplifier; Joseph Marshall. I , Jan, 17; II, Feb, 22.
Low dis tortion tone-control amplifier;
W. B. B ernar.d. Aug, 17.
New amplifier has bridge-circuit output; D. J. Tomcik and A. M. Wiggins.
Nov, 17.
Simple high-quality phono amplifier;
R. D . Middlebrook. Aug, 20.
Simplexing a standard amplifier; .R. S.
Houston. Nov, 86.
Some experiments with miniature power
tubes ; Geoffrey H. Grey., Apr, 19.
Transformerless 25-watt amplifier fo!'
conve ntional loudspea kers; D. P .
Dickie, Jr. and A. Macovski. June, 22.
Transient response of audio amplifiers;
AUDIOLOGY. Mar, 10.
'.rransistor phono preamp for magnetic
pickups; Basil T. Barber. Oct, :lS.
Transistor remote amplifier, A; Paul
Penfield, Jr. Sept, 26.
Variable
damping
fa ctor
control;
Charles A. Wilkins. Sept, 81.
At H ome with AUDIO, Lewis C. Stone.
I, Apr, 2S; II, May, 22; III, June, 24;
IV, July, 2S; V, Dec, 26. _
ATTENUATOUS
Chart of resistor values for L - pads, H .
Petel' Meisinger. Nov, 25.
AUDIO AUDITIES, Saul J .White. I, May,
55; II, June, 27; III, July, 12; IV, Aug,
74.
AUDIOLOGY, W. R. Ayres
Amplifier bandwidth. Feb; 12.
Feedback from output transformer t ertiary: Jan. 10.
T r ansient response of audio amplifiers,
Mar, 10.
~y.DIO ·
•
D~eEMBER,
Better audio specs needed; Nathan Grossman. Sept. 86.
BOOK UEVIEWS
Data and Circuits of Modern R eceiving
and Amplifying Valves, Supplement
2; N . S. Markus and J. Otte. Feb, 14.
Electronic Musical Ins trument Manua l,
The; Alan Douglas. 1\ug', 7S.
Electronic Organs; Robert L . Eby. Feb,
65.
Harmonics, Sidebands ,and T ransients
in Communication Engineering; C.
Louis Cuccia. Nov, 62.
Low-Frequency Amplification; N. A. J.
Voorhoeve. }Iar, 5S.
Principles of Transistor Circuits; Rich ,
ard F. Shea. Jan, 59.
Radio D a ta Ch a rts ; R. T . Beatty. }Iar,
5S.
Vacuum Tube Oscillators; William A .
Edson. :Feb, 14.
BUOADCAS'l'ING
Broa dcast con solette for the an n ouncer ;
L eo F . Goellel', Jr. June, 19.
Simplexing a standard amplifier; R. S.
Houston. Nov, 36.
Building your own hi-fi furniture; Irving
Greene and J a m es R. Radcliffe. I, }Iay
24; II, June, 2S; III, July, 32.
Chart of resistor values for L-pa ds; H.
Peter Meisinger. Nov, 25.
Cinerama Awards. Nov, 34.
Concre te Monster, The; J a m es Ferguson ,
July, 17.
Conductors a nd r ecord buyers; Rudo S.
Globus. Feb, 32.
Control unit for the Williamson ; Charles
R. Miller. Sept. 19.
Corner hprn design ed for the sm a ll room ;
Wayne B. Denny. Feb, 21.
Damping of loudspea ker cabinet pa n els ;
M. Rettinger. Sept, 34.
Damping factor control, Variable; Charles
A. Wilkins. Sept, 31.
De-emphasis networks in FM tun er s;
H erma n Burs tein. June, 21.
.Design of a continuously variable lowpass filter using feedback techniques;
Basil T. Barber. Mar, 26.
Design of a profess iona l t a pe recorder ;
William F. Boylan a nd William E . Goldstandt. Jan, 20.
Dual-channel control amplifier for stereophonic systems; Wayne B. Denny. }Iay,
17.
ELECTUONIC MUSICAL
INSTUUMEN'fS
Alla~ organ, The; Richard H . Dorf.
July, 20.
Employer's rights in employee's invention; Albert Woodruff Gray. Oct, 37.
EQUALIZEUS
Accurate design of phono equalizer;
Charles F. Hempstead and Hamilton
Barhydt. I, Aug, 22; II, Sept, 24.
Simulated r esonant circuits ; Glen
Southworth. Nov, 20.
EQUIPMENT UEPOUTS
Acoustical Quad II ; May, 2S.
Ampex 600 tape recorder; July, 38.
Ampex 620 amplifier-loudspeaker; Dec,
40.
Bogen DB15G amplifier and R640 tuner;
Aug, 59.
Brociner UL -l amplifier, A-lOO preamplifier, CA-2 control unit; Nov, 42.
Crestwood 401 tape recorder and 402
a mplifier; Oct, 50.
Fairchild 215 series phonog r a ph pickups and 280 s eries pickup arms; Oct,
52.
F is her 50-F filter; May, 30.
Freed-Eisemann P-717 receiver; lIay,
80.
Garrard RC-90 record changer; June, 38.
Gen eral Electric line, The: June, 34. ,
H a rmon-Kardon A-lOO AM-FM tuner;
}Iay, 30.
L a bora tory for Electronic Engineering
loudspea ker; Oct, 54.
Leak TL/ IO amplifier; July, 34.
Miracord XA-lOO Magic-Wa nd r ecord
c h a ngel'; Aug, 60.
National Criterion AM-FM tuner , Horizon 20 amplifier, Horizon 5 preamplifi e I' ; Sept, 46.
Pilot FM-607 Pilotuner; Mar, 32.
Pilot AF-860 AM-FM tuner; Oct, 54.
Pilot AA-903 amplifier; Mar, 32.
Radio Craftsmen C-350 preamplifierc ontrol unit ; Dec, 39.
R a dio Craftsmen C-500 amplier; Apr,
32.
Radio Craftsmen C-800 tuner; Apr, 32.
Rauland 1811 amplifier; Nov, 46.
Ronette TO-284-P crystal cartridge;
Dec, 42.
Shure 333 cardioid microphone ; Nov,
40.
University "Companion" loudspeaker;
July, 36.
UTC linear standard amplifier , model
MLF; June,3S.
V -M tape recorder, model 700; Dec, 40.
,Vha rfedale R-J speaker; Nov, 42.
FANTASY AND FICTION
Hi-Fi Manship at the Fair; Charles R.
Sinclair. Oct, 29.
From High Fidelity to Music; Zygmunt
Hof. Sept, 30.
Theory and practice of'ID-Fi-Manship;
Charles R. Sinclair. May, 20.
65
1954
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FEEDBACK
- - - from output tra n s former t ertia ry ; AUDIOLOGY. Jan. 10.
- -- channel sepa l'ators ; N . H . Cr owhurst. Oct, 32.
Design of a continuously v a ria ble lowp ass filter using feedbac k t echniqu es;
Bas il T . Barber. Mar, 26.
FILTERS
Des ig n of a continuous ly varia ble lowpa s s filter u s ing feedbac l{ techniques;
Basil T . Barber. }Iar, 26.
F~I TUNERS
De-emphasis networks in - --; H er\ m a n Burstein. June, 21.
Selectin g and improving - - - ; Cha rles
Erwin Cohn. Sept, 42.
Frequency and tra nSient r esp onse in
audio equipment; Charles P . Boegll.
Feb, 19.
F r om hig h fide lity t o mu s ic ; Zy gmunt
Hof . Sept, 30.
.HANDBOOK OF SOUND REPRODUCTION, Edga r M , Villchur.
Picku ps a nd t one arm s, Cha p . 16 : Feb,
33.
P ower Supply, Hum, Noise, Cha p. 15,
part 2; Jan, 27.
System assembly, Cha p. 17 ; Mar, 30.
Testing a nd m easureme nt, Cha p. 18;
Apr, 26.
Hi - Fi-Ma nship at the F a ir ; Ch a rles R .
Sincla ir. Oct, 29.
Hi-Fi sets of yesteryear; Cha l'les N . F a illieI', J r. Feb, 2B.
HOME ~IUSIC SYSTEMS
At H om e w ith AUDIO ; Lewis C. St on e.
I , Apr, 2B; II, May, 22; III, June 24 ;
IV, July 2B; V, Dec, 26.
Building y our own hi-1i furniture.
Irving Green e a nd J ames R. R a dcliffe . I, May, 24; II, .June, 2B; III,
July, '32.
Phones for fidelity; P et er W . Ta ppa n.
Nov, 22.
Place your mus ic decora tively; Irving
Greene. Feb, 24.
Planning your home mus ic insta lla tion ; Irving Greene a nd J a m es R .
R a dcliffe. I , Mar, 22; II, Apr, 22.
Horn, Th e; Edwa rd V. K e tcha m , J r. Dec,
23.
'
Hum a nd Nois e , Cha p. 15, pa rt 2, H a ndbook of Sound Reproduction ; Edgar M.
Villc hur. Jan, 27.
Improv ed' phonogra ph compen sation circuits ; R . H . Brown. Nov, 2B.
Improv ing
loudsp eal{er
perform a nce ;
D a vid B. Weems. Sept, 22.
INDUSTRIAL SYSTEMS
Security sound system ; Ala n P . Ches ney. July, 24.
Inventions, Employ er s' rig hts in employees' - - - ; Albert Woodruff Gray,
Oct, 37.
Juke box goes hi-fi, The; C. G . McProud.
Dec, 33.
LOUDSPEAKERS
Adve ntures with a ba ss r e flex ; Milton
S. Snitzer. Jan, 26.
Concrete monster, The ; Jame s Ferguson. Jnly, 17.
Chart of resistor values for L-pads; H.
Peter Meisinger. Nov, 25.
Corner h orn designed for the sma ll
room; W a yne B. D enny. Feb, 21.
Da mping of loudspeaker ca binet pa nels ; M. R ettinger. Sept, 34.
Horn , Th e; Edwa rd V . Ketcham, Jr.
Dec, 23.
Improv ing loudspeak er performa n ce ;
D a vid B. W eems. Sept, 22.·
Juke b ox goes hi-fi, Th e; C. G. Mc PrOUd. Dec, 38.
Labor a t or y s tandard loudspeaker system; D a niel J. Plach a nd Ph (lip B .
Willia m s. Oct, 84.
Loudsp ea ker s a nd Enclosures (a section); Aug, 27.
Nomograph for r e fl ex loudspeaker enclosures ; J oseph F. Soda ro. May, 31.
My philosophy on the loudspeak er m ys tery ; L eung Cho Yuk. .Jan, 5B.
R ev olutiona r y loudspea k er a nd en cloSUl'e ; Edgar M. Vill chur. Oct, 25.
Low distortion ton e-con t r ol a mplifi er ;
W . B . Berna rd. Aug', 17.
jU EASUREMENTS
T echniqu es of micr ophone calibra tion ;
Alexis Badma ieff. Dec, 30.
T es ting a nd measu rem en t , H a ndbook
of Sound R eprodu ction , Ch a p. 18 ;
Edgar M. Villchur. Apr, 26.
Tra n s ie nt a nd freque n cy. r espon se in
a udio equipm e n t; Ch a rles P. Boegli.
Feb, 19.
White sound tes tin g ; Rich a rd C. Hitch cock, Oct, 41.
Medium power t etrode a m plifier with s ta bilized s creen supply ; CulIen H . McPherson . Feb, 30.
Micr ophon e, T echniqu es of - - - ca li br a tion ; Alexis Badma ie ff. Dec, 80.
Mot or r umble r eduction in w ide -ra nge
phon ograph s ; J ohn R. Ca t er . N o~' , 32.
N ETWORKS
D e -emphasis - - - in FM t u n ers ; Hel' man Burstein. June, 21.
F eedbacl;: ch a nnel s epa rator s ; N. H.
Crow hurst. Oct, 32.
New a m plifi er has brid ge -circuit ou t pu t ;
D. J. T om cik a nd A. M. W iggins . Nov,
17.
New Golden Ear a m pli fier , The; J ose ph
Marsha ll. I , Jan, 17; II, F eb, 22.
Nom ogra ph for re flex lou dspeak er e n clos u res; J oseph F . Soda r o. }I ay, 31.
N otes on " preamp with presen ce"; C. G.
McProud. May, 52.
Phones fo r fi delity; Peter W. T a ppa n.
Nov, 22.
PHONOGRAPH R~PRODU C TION
Accurate des ign of phono equalizer s;
Charles F. H emps t ead a nd H a milton
Ba rhy dt. I , Aug, 22; II, Sept, 24.
I mproved ph onograph compe nsati on
circuits; R . H . Brown. Nov, 28.
Mot or rumble r eduction in wide-ra nge
phonographs; John R. Ca t er. Nov,
32.
Pickup loading and its e ffect on fre quen cy r esponse ; W . A. FitzMaurice
a nd W . Joseph. July, 19.
Pickups and tone a rms , H a ndbook of
Sound Reproduction, Cha p , 16; Edgar
M. Villchur. Feb, 83.
Tra nsistor phono preamp for magnetic
pickups ; Ba sil T . Barber. Oct, 3B.
Place your music decora tively ; Irving
Greene. Feb, 24.
Planning your home music installa tion ;
Irv ing Gr eene a nd James R . R a dcliffe.
I, Mar, 22; II, Apr, 22.
Powel' Supply, hum, noise , Handbook of
Sound Reproduction, Cha p. 15, pa rt 2;
Edgar M . Villchur. Jan, 27.
PREA}IPLIFIERS
New Golden E a r a mplifier ; J oseph Mars ha ll. Feb, 22.
Preamp w it h presen ce ; C. G. McProud.
Jan, 23.
Notes on the " preamp with presen ce" ;
C. G. McProud. May, 52.
Tra n s istor phono preamp f or m a gnet ic
pic kups; Ba sil T. B a rbe r . Oct, 38.
]~E C ORDING, MAGNETIC
P r oble m s involv ed in m agn e tic tape recording ; Norma n E . Gibbs. ~Iar, 19.
D esig n of a professional ta pe r ecorder;
Willia m F. Boy la n a nd Willi a m E.
G olds tandt. Jan, 20.
RECORDS
Condu c tors a nd r ecord bu ye l's ; Rudo
S. G lob us. F eb, 82.
R ecord revoluti on a nd m us ic, The;
Rudo S. G lobus. IUar, 29.
R ig h t ear for mu s ic, The ; R udo S.
Globus. Apr, 25.
Security sound syst em ; A la n P. Ch es ney.
July, 24.
Selecting a nd improving F M r eceiver s ;
Cha rles Erwin Cohn. Sept, 42.
Simple hig h-qua lity phono amplifier, A;
R. D. Middlebrook. Aug, 20.
Simplexing a s ta nda rd a mplifie l' ; R . S.
Hous t on. Nov, 36.
Simula t ed r esona nt circuits; Gle n Sou thw orth. Nov, 20.
Som e exp eriments with miniature p ower
tu bes ; Geoffrey H. Gr ey. Apr, 19.
Sound diffus ion in r ooms; M. R ettinger.
Aug, 19.
STEREOPHONIC REPRODUCTION
Dua l- channel control a mplifier for - -;
Way ne B . D enny. May, 17.
Ster eophonic lis t en er tests ; J a m es Cunning h a m a nd R obert Oa k es J ordan.
Aug, 56.
Ster eophoni c n om en cla tu re;
N . M.
H a y n es. Jan, 19.
Ster eophonic r eprodu ction ; R. Ver m eule n. Apr, 21.
System assembly , H a ndbool;: of Sou nd
R eprod Uc tion, Cha p. 17 ; Edgar M. V ilI chur. May, 30.
Techniqu es of microphone ca libration ;
A lex is Badma ie ff. D ec, 30.
Theor y a nd practice of Hi- F i-Manship,
Th e; Cha l'les R. Sincla ir. ~Iay, 20.
Transformerless 25-watt amplifier for
loudspea k er s ;
D. P.
conventiona l
Dickie, Jr. a nd A. Ma covs ki. June, 22.
T RANSIE NT RESPONSE
Tra n sient a nd frequency r esponse in
a udio equipm ent ; Cha rles P . Boegli .
F eb, 19.
- -- of a udio a mplifiers; A UDIOLOGY. Mar, 10.
TRANSISTORS
Tra n s is t or ph ono prea mn for m a gne tic
pickups; Basil T. Barber. Oct, 38.
Transis tor remote amplifier, A ; P a ul
Penfield, Jr. Sept, 26.
Variable da mping factor contr ol ; Cha rles
A. Wilkins. Sept, 31.
White sound testing ; Richard C. Hitchcock. Oct, 41.
AUDIO
66
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AmericanRadioHistory.Com
•
DECEMBER, 1954
AUTHOR INDEX
Ayres, W. R.
AUDIOLOGY : Amplifier ba ndwidth ;
Feb, ]2.
Feedback from output transformer
tertiary; Jan, 10.
Transient response of audio a mplifiers;
Mar, 10.
Badmaieff, Alexis
Techniques of microphone ca libration;
Dec, 30.
Barber, BaslI T.
Design of a continuously variable lowpass filter u s ing feedback techniques;
ilIay, 26.
Transistor phono preamp 'for magnetic
pickups; Oct, 38.
Barhydt, Hamllton, a nd Cha rles F. Hempstead
Accu rate design of phono equa lizers ;
I, Aug, 22; II, Sept, 24.
Bernard, W. B.
~ow distortion tone-control amplifier,
A; Aug, 17.
Boeg'IJ, Charles P.
Tra ns ient and frequency r esponse in
a udio equipment; Feb, 19.
Boylan, WIlHam F., and William E . Goldstandt
Design of a professional tape r ecorder;
Jan, 20.
Brown, R. H.
Improved phonograph compensation
cir cuits; Nov, '28.
Burstein, Herman
De-emphasis n etworks in FM tuners;
June, 21.
Cater, John R.
Motor rumble r eduction in w ide-ra nge
phonographs ; Nov, 32.
Chesney, Alan P.
Security sound system; July, 24.
Cohn, Charles Erwin
Selecting a nd improv ing FM receivers;
Sept, 42.
Crowhurst, N . H.
Feedback channel separators; Oct, 82.
Cunningham, James, and Robert Oakes
Jorda n
Stereophonic listener t ests;. Aug, 56.
Denny, Wayne B.
Corner horn designed for the small
room, A; Feb, 21.
D ual-cha nnel control a mplifier for
stereophonic Systems', A,; May, 17.
Dickie, D. P., Jr., a nd A. Macovski
Transformerless 25 -watt amplifier for
conventional loudspeakers ; June, 22.
Dod, Ricllard H.
Allen organ, The; July, 20.
FallJer, Charles N., Jr.
Hi-Fi sets of yesteryear; Feb, 28.
Ferguson, James
Concrete monster, The; July, 17.
FitzMaurice, W. A. and W. Joseph
PickUp loading and its effect on frequency res ponse; July, 19.
AUDIO
•
Gibbs, N orman E.
Problems involved in magnetic tape
r ecording ; illar, 19.
Globus, Rudo S.
Conductors a nd record buyers; Feb, 32:
Record revolution and mus ic, The; illar,
29.
Right ear for music, The; Apr, 25.
Goeller, Leo F., Jr.
Broadcast consolette for t he a nnouncer ;
June, 19.
Goldstandt, WlIIJam E., and William F .
Boylan.
Design of a professional tape r ecorder;
Jan, 20.
Gray, Albert Woodruff
Employer's rig hts in employee's inventions; Oct, 37.
Greene, Irving
Place your music decoratively; Feb,2-1.
- - - and J a m es R. Radcliffe
Planning your home music installation;
I, Mar, 22; II, Apr, 22.
Building your own hi-fi furniture ; I ,
illay, 24; II, June, 28; III, .July, 32.
Grey, Goeffrey H.
Some experiments with
miniature
power tubes; Apr, 19.
Grossman, Nathan
Better a udio s pecs needed; Sept, 36.
Haynes, N. ill.
Stereophonic nomenclature; Jan, 19.
Hempstead, Charles F., a nd Hamilton
Barhydt
Accurate design of phono equa lizers; I ,
Aug, 22; II, Sept, 24.
Hitchcock, Richard C.
White sound testing; Oct, 41.
Hoi, Zygmunt
From hig h fidelity to music; Sept, 80.
Hou ston, R. S.
Simplexing a standard amplifier; Nov,
36.
Jordan, Robert Oakes, a nd James Cunning ham
Stereophonic listener tests; Aug, 56.
Joseph, W ., a nd W. A. FitzMaurice
Pickup loadin g and its effect on fre quency response; July, 19.
I{etclram, Edward V., .Jr.
Horn, The; D ec, 23.
Leung, ClIO Yuk
My philosophy on the loudspeaker myst ery; Jan, 58.
Macovski, A., and D . P. Dickie, Jr.
T ransformerless 25-watt amplifier for
conventional loudspeakers; Jnne, 22.
Macpherson, Cullen H.
Medium power tetrode a mplifier with
stabilized s creen supply; Feb, 30.
Marshall, Joseph
,
New Golden E a r amplifier; I, Jan, 17;
II, Feb, 22.
McProud, C. G.
Juke-box goes hi-fi, The; Dec, 33.
Preamp with presence; Jan, 23.
lIeislnger, H. Peter
Chart of resistor values for L-pads;
,
Nov, 25.
Middlebrook, R. D.
Simple high-qua lity phono a mplifier, A;
Aug', 20.
Miller, Charles R.
Control unit for the Williamson, A;
Sept. 19.
Penfield, Paul, Jr.
Transistor r emote a mplifier, A; Se}lt,
26.
Plach, Daniel J., a nd Philip B. Willia ms
Labora tory standard loudspeaker sys·
tem; Oct, 34.
Radcllffe, James R., and Irving Green
Planning your h ome music installation ;
I, Mar, 22; II, Apr, 22.
Build your own hi-fi furniture; I, ilIay,
24; II, June, 28; Ill;, July, 32.
Rettlng'er, M.
Sound di ff us ion in rooms; Aug, 19.
Damping of louds peaker cabinet panels ;
Sept, 34.
Sinclair, Charles R.
Hi-Fi-Ma n s hip at the F a ir ; Oct, 29.
Theory a nd Practice of Hi-Fi-Manship ;
May, 20.
Snitzer, ilIllton S.
Adventures with a ba ss reflex; Jan, 26.
Sodaro, Joseph F.
Nomog r aph for reflex louds peaker en ·
clos ures; ilIa.y, 31.
Southworth, Glen
Simulated r esonant circuits; Nov, 20.
Stone, Lewis C.
At Home with AUDIO; I, Apr, 28; II,
May 22; III, June, 24; IV, July, 28;
V, Dec, 26.
Tappan, Peter W.
Phones for fidelity; Nov, 22.
Tomclk, D. J., a nd A. M. Wiggins
New a mplifier has bridge -circ uit ou tput ; Nov, 17.
Vermeulen, R.
Stereophonic r eproduction; Apr, 21.
Villchur, Edg'ar M.
Handbook of Sound R eproduction:
Power supply, hum, n oise, Chap. 15,
part 2, Jan, 27; System assembly,
Chap. 17, Mar, 30; Pickups a nd tone
arms, Chap. 16, Feb, 33; Testing a nd
measurement, Chap. 18, Apr, 26.
Revolutionary loudspea k er a nd enclos ure; Oct, 25.
Weems. DavId B.
Improving loudspeaker performance;
Sept, 22.
White, Saul J.
AUDIO AUDITIES: I , May, 55; II,
June, 27; III, July, 12; IV, Aug', H.
WIggIns, A. ill., and D. J. Tomcil{
New amplifier has bridge-circuit output ; Nov, 17.
Wilkins, Charles A.
Variable damping factor control; Sept,
31.
WllIJams, Philip B., and Daniel J. Plach
Laboratory standard loudspeaker system ; Oct, 34.
67
DECEMBER, 1954
www.americanradiohistory.com
AmericanRadioHistory.Com
ADVERTISING
IN DE X
•
FOR YOUR OWN
HIGH FIDELITY
SOUND SYSTEM
The New Wright & Weaire Tape Deck
This fine example of English mechanical precision and high quality performance has
THREE DISTINCTIVE FEATURES
Recordings can be heard while they are being made. In addition to Record Playback and Erase heads, there is a Third Head for Simultaneous Monitoring.
Reels of 8 1/2 " diameter can be used, with 1750 feet of tape, giving 45 minutes
of recorded music on each of the Two Tracks.
Allied Radio Corp. . .. . .. . ... . . ..... 49
Altec La nsing Corporation . . ..... . . . . 6
Ampex Corporation ..... ... . ... . .... . 5
Audak Co . .. . . . ... .. ... .. .. . . . •. •. . 64
Aud io Devices, Inc. • . ... . .. , . . .. Cover 2
Audio Fair-Los Angeles . . ......... . . 68
Aud ioge rsh Corporatio n . ....... .. . . . • 37
Bel de n Mfg. Co. . . . .. ... . . .. . . . .....
Bell Sound Systems, Inc. . . . .. .... . . . .
Bell Tele phone Laboratories . ...... . . . •
Bogen, David Co. , Inc. . . .... .
British Industries Corp. •. .... ... . ... •
Brush Electronics Company .. ... . . .. ..
0
•
•
•
•
•
•
13
60
22
41
3
57
Carter Motor Co. ... . ... . . • .. . .. . . .. 58
Cinema Engineering Co. . .....
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Classified Advertisements .. . . . • . . . 62, 64
0
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There are Three Motors. Capstan motor is synchronous.
The High Fidelity enthusiast can easily add this unit to his
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Response 50 to 12,000 cps at 7V2". WOW and flutter less than 0 .2 %
Speeds 3%" and 7 V2 ". Longterm speed stability better than 0.5%
Compl e~~a;~s~i~a;g:c.i~ l. ~~~.~o.n.e.n.t~ .f.O~ . . . . . . . . . . . . ..
Tape deck alone
. . . .... . . . .•. . .. . . . . ... .. . . . ....
$225.
$195.
Electro-Voice , Inc . ••.•.... .... . I, 34, 35
Electro-Voice Sound Systems ..... .... . 63
Fenton Company ... . . .. . . . . . .. .... . .
16
G & H Wood Products Co . ...
Good mans Industries, Ltd. • . ..
53
11
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AUDIO ·F AIR LOS ANGELES*
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THE ALEXANDRIA HOTEL / FEBRUARY 10, 11, 12, 13, 1955
•
PLAN NOW TO ATTEND
0
•
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ADMISSION FREE TO ALL EXHIBITS
.. In the Interests of the consum er as well as
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space has bee n limited to Aud io
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•
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Hartley. H. A., Co., Inc. . .. .
Harvey Radio Co., Inc. .. . ..... . . .. . •
Heath Co . . . .. .... .... . .. .. . .. ..... •
Hi gh-Fidel ity House . . . .. . .. . ...... ..
Hollywood Electronics • • .. .. ... . . . ...
Hughes Resea rch and Development
Laboratories ...... . . . . . . .. ... . .. . .
Hycor Co., Inc.
................
0
6 2 1 Ea
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Intere lectronics
••••
••
•
68
51
59
63
63
2
57
. . . . . . .. .. ... ... .. 16
I K M Incorporated .. . . .. . .. . . •... . . . 64
Kierulff Sound Corporation ....... . .. . . 63
Kingdom Prod ucts, Ltd. . . . ... . .
62
0
•
•
•
•
•
•
Leonard Radio, Inc . ... ... : . ........... S5
Marantz, S. B. .. . . .. .. . ....• • . . .•. • . 52
Mercury Scientific Products Corp. ..••.. 62
National Company
. ... .. .•.. . . • ... . .
Omega Electronics .. . ..
0
•
•
•
•
•
•
•
•
•
•
•
•
9
49
•
Partridge Transformers, Ltd . . . • .. .. . . .
Peerless Electronic Products •.. . ... . ..•
Permoflux Corp. . •..•
Pickering & Company, Inc . • ..... . .. ...
Pil'ot Radio Corp.
Presto Recording Corporation .. .... . . . •
Professional Directory •
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61
63
14
19
45
17
63
Radio Craftsmen. Inc. , The . .. . . .. . .. 47
Rauland-Borg Corporation ... ... . .. . .. 56
Reeves Soundcraft Corporation ... ... •.. 21
Rek-O-Kut Company
43
Rockbar Corporation
Cover 3
Ronette Acoustical Corporation 0. . . . . . . 7
0
0
0
0
••
•••
••
••••••
•
0
•
•
•
•
•
••
•
Shure Brothers, Inc. 0. . ..... . . . . . ..
Sonotone Corporation . . ••.••••
0
0
•
0
•
•
..
•
••
Tannoy (Canada) Limited . . . .. .. .....
Tech-Master Products Co. . .... . . .
Triad Transformer Corp. ... .• . . . . . ...
Tung-Sol Electric, Inc ... . ... .• 0. . .. . ..
Turner Company, The
0
••••••
••
•
0
•••
0
•
•
•
4
12
8
48
20
1S
54
United Tra nsformer Co . . . . .. . .. . . Cover 4
U. S. Recording Co . . .. .. . . .... . ... ... 63
•
FOR INFORMATION , WRITE : WILL.IAM L. . C ARA , FA I R MANAGER. 358 S . BENTL.E Y AVE . , L O S ANGELES 49 • RI 7. 46 50
68
AUDIO
www.americanradiohistory.com
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•
DECEMBER,
195~
\
the NE\N
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W
e had always considered the expression - high
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M Q S e a'ies
Compact Her m e tic
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. too
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T o rnld Indu ctors
I
Q
The MQ permalloy dust toroids
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is excellent under varying volt·
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affords shielding of approximately
80 db.
a
~
OJ
I
"
I)
to
MQA
19 stock values
f rom 7 Mhy.
t o 22 Hy.
20 2:'303)4(1
MQE
15 stock values
from 7 Mhy.
t o 2.8 Hy.
15"
""
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MOS-5
100
11
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(; 2$.., .75 I
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"
7
.......
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MQB
12 stock values
from 10 Mhy.
to 25 By.
1fT'"
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MQA- lO
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1"-
""-
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I.'
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I.'
.
i..t
,.
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..
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.
VO HAOI
.u
,
so
"
1000 ( 1'CU'
Q ' lO
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VI C case struct ure
Length
Height
Width
1·1/ 4
1·11 / 32
1-7/ 16
.'"
'00
....
'''~UUjC '.( l' n u
l OW'. Am"..
...
VIC·1
VIC·2
VIC·3
VIC-4
VIC·5
VIC·S
IVIC·7
VIC·8
VII!·g
VIC·10
VIC·11
CaL Low P_qu enClf High Q Col'a
"
i··t----t-- ---+----I
Variable Inductors
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A step forward . from our long
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~, 1== ==l=====I====I
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S P E C IAL UNITS
TO YOUR NEEDS
Send you ..
spec ific a t i o ns
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.......
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".('
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.053
•084
.13
•21
.34
.54
.85
The VIC Inductors have repre·
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problem ' of tuned audio circ_uits.
A set screw in the side of the
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inductance from + 85% to - 45%
of th e mean value. Setting is
positive.
Curves shown indicate effective
and L with varyi ng frequency
and appl ied AC voltage .
1 . ~.
2.2
3.4
5.4
8.5
13 •
21.
33 .
52.
83.
130.
a
DI Indu ctance Dec,o des
a.
These decades set new standards of
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laboratory adjusted to beUer than 1%. Units housed
in 3 compact die cast case with sloping panel ideal
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VI C V a riabl e I n ductors
Meall
Hys.
Type
VIC·12
VIC·13
VIC·14
VIC·15
VIC·16
VIC·17
ViC·18
VIC·19
VIC·20
VIC·21
VIC·22
10,000
:-rile Mat. series of high Q coils employ special
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Q at low ~ elluencies with excepti(mal stability (or
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Two identical windings permit series, parallel, or
transformer type connections.
H V C Herm e tic
Mean
Hys.
Type
'\.
r--...
-
U NI T ED
/1 1
Jj-
/
Type
No.
. " .... STt·
II
Min.
Hys.
.OQ2
:005
HVC·1
HYC·2
HVC·3
.011
HYC-4
.03
HYC-S
.07
HVC·6
.2
NVC-7
.5
HVC·8
1.1
HYC·9
3.0
HYC·10
7.0
HVC·11 . 20
HVC·12 · 50
~
"
0 1·1 Ten 10 Mhy. steps.
0 1·2 Ten 100 Mhy. steps.
01 ·3
Ten 1 Hy. steps.
0 1·4
Ten 10 Hy. steps.
Mean
H1s,
.006
.015
.040
.1
.25 . .
Max.
Hys.
.02
.05
.6
2
1.5
4 .0
10
25
60
150
' 01 DECADE
Length .........................41/, "
Wi dth ....................._ .....4% "
Height ......."..._ ....__ 2%"
.11
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30
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200
500
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EXPO RT DIV IS IO N: 13 E: 40th 51., N ew York 16, N . Y. CAB LES: "A RlAB"
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