exmpealft4Ify6te abl6ae4ydet4./ La' AmericanRadioHistory.Com "The lowest noise figure and highest sensitivity permitted by the present state of the art" harman kardon For High - Fidelity FM Tuners. HARMAN - For Television Tuners. RCA -6CW4 nuvistor KARDON, nationally recognized as a manu- triode in VHF TV Tuners makes possible satis- facturer of stereo and hi -fi components of the factory reception in fringe areas and other loca- highest quality, has designed the front end of its tions where signal levels are extremely weak. This Citation III FM Tuner to take advantage of the tiny tube with giant performance gives RCA exceptional performance capability of the RCA - Victor's New Vista tuner up to 45',1 more picture 6CW4 nuvistor triode. Why :' Because in the words pulling power in weak signal areas than the best of Harman -Kardon, "The revolutionary nuvistor tuner previously available. It has proved so suc- furnishes the lowest noise figure and highest sen- cessful that RCA Victor has introduced 12 new sitivity permitted by the present state of the art." color -TV receivers with the nuvistorized tuner. Nuvistors can make extraordinary contributions to industrial and military as well as entertainment electronics. Discuss them soon with your RCA Field Representative or write Commercial Engineering, RCA Electron Tube Division, Harrison, N. J. The Most Trusted Name in Electronics RADIO CORPORATION OF AMERICA RCA FIELD OFFICES: EAST: 744 Boad Street. Newark 2, New Jersey, HUmboldt 5-3900 MIDWEST: Suite 1154. Merchandise Mart Plaza, Chicago 54. Illinois, WHitehall 4.2900 WEST: 6355 E. Washington Blvd.. Los Angeles 22, California, RAyrrsond 3 -8361 1838 El Camino Real, Burlingame. California, OXford 7.1620. AmericanRadioHistory.Com MAY, 1961 VOL. 45, No. 5 Successor to RADIO. Est. 1911 C. G. McPROUD Editor and Publisher DAVID SASLAW SHERWOOD uDI0 Managing Editor JANET M. DURGIN Production Manager HENRY A. SCHOBER Representatives Contributing Editors Business Manager Bill Pattis & Associates, EDWARD TATNALL 6316 N. Lincoln Ave., CANBY SANFORD L. CAHN JOSEPH GIOVANELLI Advertising Director Chicago 45, Ill. James C. Galloway, HAROLD LAWRENCE EDGAR E. NEWMAN 6535 Wilshire Blvd., CHARLES A. ROBERTSON Circulation Director Los Angeles 48, Calif. CHESTER SANTON Intraducs AUDIO Articles .'' Feedback Techniques in Low -Level Amplifiers 19 Donald L. Shirer .: Confessions of a High Fidelity Widow 24 Christopher Faye {' Tape Guide -Questions and Answers 30 Herman Burstein The Indispensable Engineer 36 Norman H. Crowhurst How High is Fi? 40 George Fletcher Cooper New S]UUU AUDIO Reviews Light Listening 8 Chester Santon Stereo FM/AM Record Revue 55 Edward Tatnall Canby Jazz and All That 60 Charles A. Robertson Receiver AUDIO Profiles 50 watts '299" Fisher FM -200 FM Tuner 46 Garrard Type "A" Turntable 48 only for those who want the ultimate.. FICO ST-40 Stereo Amplifier 50 Goodmans "Alpha" Speaker System 52 Audio Dynamics ADC -1 Stereo Cartridge 52 ... a triumph in combined components, AUDIO in General the S -7000 brings together in one unit the incomparable features of Audioclinic 2 Joseph Giovane /li Sherwood's FM and AM tuner circuitry Letters 6 along with two 25 -watt amplifiers, two pre -amplifiers and stereo controls. AUDIO ETC 10 Edward Tatnall Canby The S -7000 needs only the addition of Editor's Review 16 speakers to complete a basic stereo IHFM Page system. Overall size, just 16 x 4 x 14 28 inches deep. New Products 66 New Literature 69 ... a dramatic new furniture concept - Sherwood Correlaire Modules About Music 70 Harold Lawrence - styled with a contemporary flair in This Month's Cover 81 hand -rubbed Walnut and Pecan woods. Industry Notes 83 Sixteen interchangeable modules for truly flexible room arrangements, Advertising Index 84 the perfect setting for your Sherwood components. Sherwood Electronic Laboratories, Inc., 4300 N. California AUDIO (title registered U. B. Pat. OR.) is published monthly by Radio Maga- Ave., Chicago 18, Illinois. zines, Inc., Henry A. Schober, President; C. 17. McProud, Secretary. Executive and Editorial Offices, 204 Front St., Mineola, N. Y. Subscription ratas -U. B., Possessions. Canada, and Mexico, $4.00 for one year, for two years; all $7.00 FOR COMPLETE TECHNICAL DETAILS WRITE DEPT. A -5 other countries $5.00 per year. Single copies 5o e. Printed in U.B.A. at 10 -1 McGovern Ave., Lancaster. Pa. All rights reserved. Entire contents copyrighted 1961 by Radio Magazines, Inc. Second Clase postage paid at Lancaster, Pa. RADIO MAGAZINES, INC., P. O. Box 629, MINEOLA, N. Y. Postmaster: Send Form 3579 to AUDIO, P. O. Box 629, Mineola, N. Y. AUDIO MAY, 1961 1 AmericanRadioHistory.Com 20, JOSEPH GIOVANELLI The compatible record? However, some studies indicate that some stereo information is carried by the Q. Stereo records have been with us for bass component in the music. This would quite some time now, and yet I have heard indicate that removing the lows from the recently of a disc which is called a com- vertical component of the record would 000 patible stereo disc. I thought that the discs lead to sonic degradation of quality in we are already using are compatible with terms of special realism. monophonic requirements. What is this new This, then, is the design philosophy be- disc? Nario Brenes, New York, N. Y. hind the compatible disc. It seems to me D OLLARS A. You are, of course quite correct in that we should really call this recording saying that the present stereo disc is com- technique the "more compatible" record. patible with monophonic discs, at least After all, we already were talking about in that the stereo cartridge can, merely by compatiblity, and this system brings us, strapping its two outputs together, re- so some say, more compatibility than merely produce a monophonic recording as well as compatible. It is something like the idea the standard monophonic cartridge. of high fidelity, and as Edward Tatnall Of course, record dealers and manufac- Canby often writes. "How high the fie" 14° turers would like to make a record which could be played equally well with standard Solid -State Tube Replacement monophonic or stereo cartridges. This should be done with no degradation to the Q. I have read recently about solid -state sound quality or of record life, regardless of tube replacements. Are these units transis- which cartridge is being used. As I have tors? Arthur Darrow, Albany, New York. stated previously, the monophonic disc can A. I believe that what you have in mind e be successfully reproduced by a stereo car- is the replacement for standard tubes. What is merely some diodes placed in an The NEUMANN PA2a tridge, however the stereo record cannot this is be reproduced so satisfactorly by a mono- ordinary octal base. These are silicon diodes AUTOMATIC INTEGRATED TURNTABLE, phonic cartridge because the monophonic so wired that the unit is directly inter- ...built to satisfy the playback re- unit is likely to have poor vertical compli- changeable with the tube it replaces. quirements of the $20,000 *Neu- ance. Further, the poor vertical compliance The purpose of such a unit is to improve mann- Teldec AM -32b lathe and of monophonic cartridge leads to reduced voltage regulation of the power supply and stereo cutting system, is now avail- record life. to permit cooler operation of the equip- able in limited number for home use. After considerable experimentation, De- ment with which it is associated. You see, Frankly, the PA2a was never meant to sign- Records came to the conclusion that it silicon diodes have a considerably lower be sold on a mass basis, because the was the vertical signal at low frequencies forward resistance than vacuum tubes have, engineering and precision that goes which caused most of the wear. They and this means that the voltage drop within into its manufacture, unavoidably further believed that it would not make the solid -state tube replacement rectifier raises the cost of the PA2a above the much difference to directionality or spa- will be less than that for the standard range of most ordinary turntables. But ciousness if the lows were removed from vacuum tube. I measured the difference in the audiophile who seeks rumble free the vertical component of the stereo disc. performance myself, using an amplifier operation, wow and flutter at less than The bass would still appear in the lateral with a pair of 6í.6's in the output. The 0.06% RMS, the realism achieved component which represents the sum of the circuit called for a 5Y3 and I measured through the incomparable Neumann two channels, and hence, would be repro- the voltage appearing on the cathode of DST Stereo Cartridge and the auto- duced as well as on the conventional stereo this rectifier. When I substituted the solid - matic integrated tonearm, and who disc. (Remember that the vertical infor- state tube replacement, I found that the places perfection above everything, mation represents the stereo information, voltage was higher by some 50 volts. will recognize the economy in this equal to the difference between the signals This fact should indicate caution in sub- once -in -a- lifetime investment. To see, of each channel. This is the same sort of stituting these units in a circuit. Suppose hear, and compare the PA2a is an ex- thing which is encountered in multiplex that you have an amplifier which has a perience no one should miss ... but broadcasting where the stereo information capacitor input filter and which has 425 the next best thing is detailed litera- is represented by the difference subchannel volts appearing between the cathode of ture available on request. and the monophonic component is repre- the rectifier and ground. If you substitute sented by the main carrier signal.) Re- the solid -state device, this voltage can rise exclusively imported by Gotham Audio Corporation cordings have been made using this prin- to 475 volts or higher, depending upon the write to sole U.S.