Audio-1952-09 电路图.pdf

,. .- . . . . . -.,; +. . . .fi., 4., . I 11 . , . .1-;. .:.,:v., 1 E.a,- - , ;r-r , <Z IZ I I -$ . Ii p RadioFans.CN 收音机爱 好者资料库 FULL DIMENSIONAL SOUND Lifts HI-FI to a new HIGH - thanks to the finest In modern sound recording methods and equipment FUL DIMENSIONAL SOUND is an apt descrip. tion of the tonal perspective that gives these fine records the true balance, depth and full tonal range of the original live performance. To achieve these outstanding results, Capi. tols sound recording methods and equipment include all of the latest technical advances in the audio field. Recording materials - both discs and tape - must measure up to the highest professional standards in every respect. And Capitol- like leading phonograph re-cord manufacturers the country over - has found that Audiodiscs and Audiotape are the ideal com bination for meeting these exacting requirements. Remember - Audiodiscs and Audiotape are made by audio engineers, lor audio engineers. Their consistent uniform quality is the result of more than a decade of experience by the only company in America devoted solely to the manufacture of fine sound recording media - both discs and tape. AUDIO DEVICES, Inc. 444 MADISON AVE NEW YORK 22, N. Y. Export Dept.: 13 East 40th St., New York 16, N. Y., Cables ARLAB I. . including Glldiatape* for the original sound _ .I!-.-I! _ * . and for the master recording . . . * Trade Mark . . RadioFans.CN 收音机爱 好者资料库 Successor to !RADIOI - Established 1917 J INCLUDINC C. G. McProud, Editor and Publisher Harrie K. Richardson, Associate Editor Luci Turner, Production Manager Lucille Carty, Circulation Manager Edgar M. Villchur, Contributing Editor S. L. Cahn, Advertising Director ,H. N. Reizes, Advertising Manager Editorial Advisory Board Representatives Howard A. Chinn John D. Colvin H. Thorpe Covington, Special Representative 677 N. Michigan Ave., Chicago II, III. C. J. LeBel Sanford R. Cowan, Mid-West Representative 67 W. 44th St., New York 18, N. Y. James C. Galloway. Pacific Coast Sales 816 W. 5th St., Los Angeles 17, Calif. J. P. Maxfield George M. Nixon Technical Book C. O. McProud, Secretary. Executive and Editorial Offices: 204 ront St., Mineola, N. Y. Subscription rates-United States, U. S. Possessions and Canada, $3.00 lor 1 year, $5.00 lor 2 years; elsewhere $4.00 per year. Single copies 35c. Printed tn U. S. A. All rights reserved. Entire contents copyright 1952 by Radio Magazines, Inc. Entered as Second Class Matter February 9, 1950, at the Post Omce, Lan- caster, Pa. under the Act of Mnrch 3, 1819. AUDIO ENGINEERING SEPTEMBER, 1952 AUDIO ATTENUAIOR Matched! Ladder aHenuators Bridged as a re- sult, sine-wave oscillations are produced. The two stages and the feedback paths are symmetrical, the frequency being con- trolled by the values of C and C., and R, * 255 W. 84th St., New Y ork 24, N. Y . r-OB+ RS Fig, and RG. The patent gives formulas by which the values of the frequency-controlling ele- ments may be approximated, but a little experimentation ,will giv!,! precise results without difficulty. This is preferable be- cause stray capacitance in tube inputs and wiring render the formulas less than exact. Fgttn 2 gives a practical circuit (sorry, the II1ventor gave no values) for a 2000-cps oscillator. The components are coded the sarJlle as in Fig. 1,. but there are more of them. The positive bias for the grids is ob- tained from a voltage divider RJI-R across the power supply and R, is added between the cathodes for max imum stability adjust- ment (equalization of cathode voltages, probably). R, and R8 have been added in the feedback paths and C, and C have been added in shunt with the grid resistors. C, is an output coupling capacitor. The impres- sive addition is R10, a variable resistor whose function, according to the inventor is to vary the B-plus voltage as a conven ient method of varying oscillation ampli- tude. A stable oscillator indeed! A strictly practIcal approach to design- ing one of these oscillators ought to. work Fig. 2 very well. Beginning with a duo-triode such as the 6SN7-GT and offhand values for plate and cathode resistors-perhaps 0.1 megohms for all four, select random values for R C, and their opposite numbers, Place variable resistors in the cathode cir- c.uits and replace RJ1 and R,. with a poten- tIOmeter of perhaps 0.1 megohms. A little knob-twiddling should quickly determine fi- nal values and frequency can be adjusted later on a ratio basis, starting with the ex- isting values and frequency. C.-C and R,R. mayor may not be necessary, de- pending on frequency . Low-Distortion Cathode-Follower Cathode-followers have found wide use as impedance-transforming circuits because of low frequency distortion, high input im- pedance, and low cost. They are, however little less subj ect to nonlinear distortio than standard stages especially ;when the C01ltintt,ed on page 6. AUDIO ENGINEERING SEPTEMBER, 1952 HEAVY DRIVE SHAn: A unique feature! Exclusive with Garrard! Dri ve shaft for 33113 rpm and 45 rpm Is heavy, obtaining more sistent quality critical low speeds. Wows and wavers eliminated. TRIPLE SPEED SWITCH: Speed changes are clearly marked, eas ily made. The RC80 plays 331/3, 45 and 78 rpm. Records are placed on the play. er and simple set- tings made. Action is then completely automatic, Includ- ing automatic shut. off after last record of any size. CONVENIENT START STOP-REJECT LEVER: RC80 turntable is heavily weighted to give flywheel action so that any varia tions in the drive motor are not re- flected In record reproduction. No turntable rumble. MAIL COUPON TODAY for Garrard Fact Sheet and addresses of dealers, PUSHER TYPE PLATFORM: Adjusts simply to 71012 records regardless of diam. eter or size of spindle hole. No record changing mechanism has been developed to equal the performance of the precision pusher platform. For records with standard center holes, the pusher platform Is the only method that gives positive gentle record operation. Speed maintained throughout a wide variation In line voltage. There is no appreciable speed variation operating unit cold with a full load or hot with one record, re- gardless of weight, thickness or diam- eter of records. IMPORTANT! Only a 4-pole motor can assure no hum when used with sensitive magnetic pickups. TWO INTERCHANGEABLE SPINDLES: Easily Inserted, the two Garrard Spindles accommodate all records as they were made to be played. (If user prefers one spindle can be. useil throughout simply by plugging center hole of 45 rpm records.) a: Typical Garrard spindle for standard center holes. b: Easily inserted wide spindle, for 45 rpm records, remains stationary when record is played. Only a small collar revolves, assuring longer center hole and record wear. Send literature to Name . . to Garrard Sales Corp., Depi. AE-9 164 Duane Street Address . . City . Zone . State . . New York U, N. Y. PULLAWAY IDLER WHEEL Avoids flattening 01 drive wheel when changer is not op erating. AUTOMATIC STOP: Insures positive and unfailing action at end of any type rec ord. BALAHCEMOUHTED TONE ARM: Parallel 11ft tone arm construction guarantees true tangent tracking. Disturbing reso nance eliminated. INTERCHANGEABLE PLUG-IN HEADS: Carefullyengi- neered to accommo- date users choice of crystal or mag- netic cartridges for standard and micro- groove reproduc- tion, such as Asta- tic, Pickering, Au- dak and GE twist 00(1 6-;JI WORLDS FINEST RECORD CHANGER GEARS Perfectly meshed to insure constant smooth action and years of service. No sound while changer operates on rUQ-in or run-off grooves. Continuity of music undis- turbed IlY noises. WATCHL1KE CONSTRUCTION All parts are preCision made, fas- tidiously assembled and simple to adjust. A complete stock of replacement parts is readil available to all Garrard owners. For an excellent description of what to look for In a record changer, we recommend the section devoted to changers in the new book HighFidelity Sim- plified, published by John F. Rider. We print this page in order to show you the superb engineering which has caused thousands upon thousands of discriminating people, who enjoy records, to insist upon the Garrard Triumph, Worlds Finest 3-Speed Record Changer. Take this advertisement to your favorite sound department, and judge for yourself! $42.30 net, less cartridges TaE EASY WAY the BC-2B Consolette han- dles is due in great measure to the careful ,attention RCA engineers have given to construction details-and to a number of unique operating features (not found in theirntirety in any standard consolette), Someqf these advantages are pictured on these pages, For e;x:ample, see how easy it.is to get at the amplifiers and components. Note how every inch of wiring can be reached with- out disrurbing the installation. See how the consolette fits snugly into the control room-unobtrusively. See how the styling matches other RCA audio and video equipments. Based on more than 25 years of experi- ence in building studio consolettes, type BC-2B is in our opinion a high point in consolette design. The instrument includes all essential elements needed by most AM- FM aQ.d TV stations. And every feature has been operation-proved-many in RCA de- luxe custom-built equipment. Type BC-2B is available at a package price! For details, call your RCA Broadcast Sales Representative. 100UCtS (OIP. AUOO -and cut cores1 square or rectangular cores-are manufactured to meet your individual requirements. RANGE OF TYPES In each of the magnetic materials named, Arnold Tape-Wound Cores are produced in the following standard tape thicknesses: .012, .008, .004, .002, .00-1, .0005, or .00025, as required. AUDIO ENGINEERING SEPTEMBER; 1952 MAGNETIC AMPLIFIERS PULSE TRANSFORMERS CURRENT TRANSFORMERS WIDE.BAND TRANSFORMERS NON.LlNEAR RETARD COILS PEAKING STRIPS REACTORS. waD 38 to assure peak efficiency and maximum uniformity. Youll find -this tube has the stuff to take the whole range of audio service require ments from protracted standby periods to repeated heavy over loads. So, if absolute reliability is essential in your audio circuits,- the Tung-Sol 5881 is a must. Order it from your regular supplier._, Write for characteristics and performance data TUNC-SOL ELECTRIC INC., NEWARK 4, N. J. Sales Offices: Atlanta Chicago Culver City (Calif.) Dallas Denver Detroit Newark T,ang-Sol makes All-Glass Seald Beam L , amps, Mlnlat . amps, Signal Fla.hers. Plctu . Tubes, Radio. TV and - -Speclal-Purpose Electron Tub . LETTERS Ungilding the Lily Sir: In your July issue you make use of the expression Gilding the Lily. I hope you will not take it amiss if I point out that this is actually a misquotation. I think the original observation about improving the lily was made by Shakespeare, in King J olm, Act IV, Scene 2, in the following words: To gild refined gold, to paint* the lily, To throw a perfume on the violet, To smooth the ice, or add another hue Unto the rainbow. I am not suggesting that because Shakespeare said something in the 16th century we must forever use the same thing; but I do think that a perusal of these lines shows that the expression To paint the lily has some meaning, whereas to talk about gilding the lily has none . G. A. Briggs, Wharfedale W ireless Works, Idle, Bradford, Yorkshire, England. (* Italics ou.rs.-An wgilded lily to Mr. Briggs for his com- ment. Since the misquotation is better known thalt the quota- tion, 111e followed poplla, r belief. ED.) Sir: We note with interest the article Gilding the Lily by Sarser and Sprinkle in the July issue of lE. Since the important por- tion of the article deals with the Ultra-Linear conversion, a circuit arrangement which we have designed, we feel privileged to comment. The authors mention that the original Ultra-Linear circuit has a tap at approximately 43 per cent of the primary winding, and that they use a tap at 50 per cent which is not too far from 43 per cent. What they fail to mention is that in our own circuit arrangement the screen load is 1220 ohms, and in their arrangement it is 2500 ohms. We know that 2500 ohms is too far from 1220 to give comparable results and that the per- formance of the circuit is degraded through misuse, although there is measureable improvement in their arrangement over the conventional triode connection. Our - patent claims cover the use of any primary tap in this circuit arrangement. However, we have restricted the use of the term Vltla Linear to the condition where the dynamic plate characteristic curves are 1/l,OSt linear. This occurs with tubes of the 6L6 and the 807 type with a primary impedance of 6600 ohms, screen impedance of 1220 ohms, a,nd a bias equal to 10 per cent of the plate-to-cathode voltage. Only this last condition has been met by Sarser and Sprinkle and it is thel-efore incorrect to refer to the Gilded Lily as Ultra-Linear. David Hafler . compared with the I%,/1 diameter of standard 7/1 reels. /J L J.! 50 D;. J1 !J.: IIL,.It,h OJ:lln Ltn Thus it has approximately the same ratio of lMfs litt1tVfOfS 0 Na(.(Ct6 PUct1 c)ru outside diameter to hub diameter as the stanC!- ard NARTB 10Yz/l metal reel. Another feature of this new reel is the single small threading slot, which minimizes mechanical distortion of Its the new Scotch brand dry. the layers of tape nearest the hub. . - -tf a /tm . tIU6 ttW/i#1pJWVep!x ioud- new Altec Lasmgd d thls week . . t mtro uce speakers, JUS ditional factoly gualan- have an uncon. f 30 to 22 000 teed freq:,en.cy lragAIec state that no cycles. Prmcla sathe market bave thJ other speakels on great a frequency ralngspeakelS, Tbese two new ou 1 . ch 60lA and the fifteen twe ve m . ns of 602A are improved versH1 J f us 604 Dup ex amo The new Altee . . LOUDSPEAKERS 60lA Net Price with network, $89.00 TtCHNICAl DATA 60lA 602A Diameter: 12P 15* Power Capacity: 20 watts 20 watls Impedance: 8 ohms 8 ohms Weight: 151bs. 251bs. rOR YEARS the Altec 604 Duplex has repre sented the highest quality attainable in a loud speaker. Now two new speakers join the 604 to provide you with an even higher standard for quality sound reproduction. These two new Duplex speakers, the twelve.inch, 60lA and the fifteeninch 602A, are the finest in the wotld. Hear and compare these guaranteeli quality speakers at your Altec dealer toddy. the Symbol of Quality GUARANTEED QUALITY: When you buy an Altec 60lA or 602A Loudspeaker, the quality of your purchase is protected with this guarantee: The Allec Lansing C?r. poration unconditionally guarantees that, when