September, 1957 I
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SEPTEMBER, 1957 I 1 The Recital TA-120, selected by American Society of Industrial Designers for official U.S. display at Milan Triennale — world's most important exhibition of industrial design Once the design of a high fidelity tuner or amplifier has been completed, the chief engineer is entirely depend- of solder. In this manner each element is locked into its ent on how well the factory can reproduce it. one best position. In a sensitive high fidelity instrument, the location of its This process has been perfected and proved in the U.S. component parts is extremely important. As little as 1/32 Guided Missile and Earth Satellite programs—and in the of an inch can make the difference between routine and production of radar and the nexv computers. Here, where emphasis is on precision, reliability and quality—and superb performance. This critical relationship can often where cost is not a factor—printed wiring is the produc- be compromised by the conventional production method tion choice. of hand wiring. Subtle wiring variations, unintentionally introduced by production people, can result in wide varia- Typical product of the marriage of creative engineering and tions in performance between sets produced on the same ideal production technique is the new Harman-Kardon Recital Model production line. TA-120. It combines a highly sensitive AM-FM tuner, a complete preamplifier and a 20 watt hum-free, distortion-free poweramplifier. Were it possible to place the chief engineer at each of If features; magnificent Armstrong FM with Automatic Frequency our forty final test positions, he could undoubtedly correct Control to insure accurate tuning automatically; sensitive AM with those compromises and make each instrument the perfect automatic volume control and built in ferrite antenna; dynamic translation of his design. loudness contour control to provide precise balance for your own Harman-Kardon has, in effect accomplished this objec- hearing characteristics; enormously effective bass and treble tone tive by the creative application of printed wiring. Its use controls to adjust for the acoustics of your room; selectable record in every Harman-Kardon tuner and amplifier has virtually equalization; remote speaker selector switch and rumble filter. eliminated human variables in production. In each instru- The Recital's "Controlled H" circuit operates so efficiently that it ment every part is in its one best position with respect to creates less heat than conventional instruments which deliver only every other part and all the interconnecting wires are of half its power output. The enclosure and control panel are finished in brushed copper, the knobs and control panel frame in matte precisely the correct length and in precisely the correct black. The Recital is 14-3/4" wide by 3-5/8" high by 10-15/16" place. This is one of the reasons why the Harman-Kardon deep. Simply plug in a suitable loudspeaker and record player tuner or amplifier you buy is certain to equal the perform- and a high fidelity system of incomparable performance and ance of the original engineering design. unique good looks is yours. The Recital Price is $1 89.95 Slightly higher in the West Printed wiring is the technique which can effect per- fect reproduction of the engineer s design every time. The FREE: Colorful, fully illustrated catalog. Describes complete Harman-Kardon line. Includes guides on how and where to buy high fidelity equipment. process literally prints the interconnecting wiring of the Send postcard to Harman-Kardon, Dept. A0^ 520 Main St., Westbury, N.Y instrument by etching it on a laminated phenolic sheet. Electrical components are fastened to the sheet by auto- kardon mation equipment and the sheet is then dipped into a bath THE BRITISH INDUSTRIES A new concept n speaker sys- tem design by G. A. Briggs NEW 3-SPEAKER SYSTEM Model SFB-3 IT is our pleasure to announce that we are now delivering the revolutionary }-way Wharfedale speaker system recently designed by G, A. Briggs, with a free-standing, sand- filled baffle. This advanced development elimi- nates cabinet resonance and produces the distinctive sound quality which experts have come to associate only with Wharfedale speak- ers. The SFB-3 is available to you now for your own home . the same 3-way speaker system with identical reproduction in a choice of two styles, ready to play. Prices are surpris- ingly moderate ... yet styling, materials and craftsmanship are unexcelled. And it is prob- ably true that you will only comprehend the outstanding performance of these new Wharfe- dale models when you A-B them against any other speaker systems at any price. (For details, please see other side.) SFB/3 Warwick Custom $J 99.00 Windsor Dduxa $249.00 NEW SFB 3 SPEAKER SYSTEM 12" low frequency driver 3" treble speaker 10" mid-range speaker • FREE-STANDING Sand-Filled Baffle • RESONANCE-FREE • OMNI-DIRECTIONAL • FULL FREQUENCY RANGE 30 cps to 20,000 cps • MODERATE PRICE Speakers: Specially built, 12" low frequency, 10" mid- range and 3" treble, tuned and integrated for optimum reproduction. Bass Resonance: 30-35 cps. Impedance: System impedance 15 ohms. Weight: Approximately 75 lbs. Size: Custom: 34" w., 31" h., 12" deep. Deluxe: 351/2" w., 311/2" h., 13" deep. Finishes: Mahogany, Walnut and Blond. SFB/3 / V 20 30 50 100 500 IK 5K lOK 70« FIEOUENCY IN CPS Impedance Curve: Note the unusually level impedance which typi- fies the wide frequency response. Note: Because the speakers are specially built and matched together with the sand-filled baffle for optimum results, neither speakers nor baffles are available separately. A quality endorsed product of the BIC Group: Garrard • Leak • Wharfedale R-J • River Edge • Genalex • S. G. Brown • Multicore. To: British Industries Corp. Dept. WM17 Port Washington, N. Y. Please send information on these and other Wharfedale speakers and systems. Name Address City State what kind of SEPTEMBER, 1957 VOL. 41, No. 9 microphone do you need ? Successor to RADIO, Est. 1917. a hand-held microphone? Hift SlWfyiiei "555 ENGINEERING MUSIC SOUND REPRODUCTION <!. G. McProud, Editor an<l Publisher Henry A. Schober. Business Manager llarrie K. Richardson. Associate Editor a lavaller Joan Dioguardi, Assistant Editor microphone? Janet M. Durgin. Production Manager Edgar E. Newman, Circulation Director TI'A SfWixjuA 535 Sanford L. Calm, Advertising Director •MEMBER- , Special Representative - Msniufi o* 11. Thorpe Covington, a desk or 814 Lincoln St., Evanston, III.. DA vis 8-8874 floor stand Mid West Representative— microphone? Sanford R. Cowan, 300 W, 43rd St., ^■INC-h New York 36, N. Y. TiiPy 535 W est Coast Representatives - James C. Gallotvay 0535 W ilshire Boulei ard. I.os Angeles 48, Calif. CONTENTS Audioclinic—Joseph GiovanelH 2 dual-impedance Coming Events 4 microphone? Lotlciv (i About Music—Harold Lawrence 8 TltA .^IWijuc/ 535 New Literature 9 Editor's Review M The Violin and Its Hi-Fi Analogies—Antony Doschek—Part 1 ... 17 A Transistor Playback Amplifier—/•'. K. Wyman 20 The Third Dimension in Sound—The Engineering Department of Uadio a microphone Craftsmen 22 Auditorium Acoustics and Control Facilities for Reproductions in Auditory with on-off Perspective—H. Bedell 24 switch? Transistor Tone Control Circuits—F. U. Waldhauer 27 Equalizer Design—Norman H. Crowhurst—Part 11 34 liift 535 Two-Channel Transistor Remote Amplifier—Donald K. Haahr 46 Equipment Review 52 —Miracord phono equipment—Acoustic licsean h .I R-X sjieakcr—(irado magnetic pickup—Audette Sr. loudspeaker Record Revue—Edward Tatnall Canby ... 58 The Slendyne "535" is an • The Slendyne omnidirectional dynamic Audio ETC—Edward Tatnall Canhy 68 can be trans- probe microphone with a Jazz and All That—Charles A. Hohertson 72 ferred from one frequency range of 60 to New Products 78 application to 1 3,000 cps. Industry Notes and People 95 another — in It is a rugged unit, designed to provide fine-quality per- Advertising Index 96 seconds — with- formance for years—without out disconnect- deviation from its original Cover photo from Antony Doschek ing the cable. critical standards. List Price $70.00 AUDIO (title registered U. 8. Tat. Olf.) is published monthly by Radio Magazines, Inc., ilenry A. Schober, President; C. G. McProud, Secretary. Executive and Editorial Offices. 204 Front St., Mineola, N. Y. Subscription rates—U. S. Possessions, Canada and Mexico, $4.00 for one year, $7.00 for two years, all other countries, $5.00 per year. Single copies 500. Printed in U. S. A. at Lancaster, Pa. All rights reserved. Entire contents copyright 1957 by Radio Magazines, Inc. Entered as Second Class Matter February 9, 1950 at the Post Office, Lancaster, Pa. under the Act of March 3, 1879. am'/ ■ )iia/dii RADIO MAGAZINES, INC., P. O. Box 629, MINEOLA, N. Y. SHURE BROTHERS, INC Microphones Electronic Components AUDIOCLINIC?? DEPENDABLE JOSEPH CIOVANELLI VERSATILE! Conversion to Stereo the tape recorder's own amplifier, while the other channel is fed into the transistorized Q. I am a musician and as such wish to preamplifier. Of course, their respective PRICED hear music reproduced as realistically as outputs are channeled into proper speakers possible. I should like to convert viy pres- and/or amplifiers. ent tape machine to stereo in a way which The head unit itself is designed to mount RIGHT! will be simple and easy, as I am not a good to the case in which the tape machine is technician. Please explain the steps neces- housed. In normal operation, threading pro- sary for such a conversion. Douglas B. ceeds through the stereo head, through the Hagen, N.Y.C. capstan-pressure roller combination, to the A. Before describing the conversion pro- take-up reel, completely by passing the ma- cedure, I shall briefly review the operation chine's own head(s).