SERIES / SM77 SM78 cardioid dynamic microphones a new look for the 80's There's so much new about these professional micro- phones we can only touch the highlights. Exclusive "pic- ture perfect" SUEDECOATTM Tan or Ebony matte finish looks great -permanently. Significantly smaller, exceptionally light in weight; yet so extraordinar- ily rugged and reliable we call them the "Light Heavyweights" They feature the crisp sound that makes Shure the world's most widely used professional performer microphones. GENUINE For more information write: Shure Brothers Inc., 222 Hartrey Ave., SHUR Evanston, IL 60204 In Canada: A. C. Simmonds & Sons Limited Manufacturers of high fidelity components, microphones, sound systems and related circuitry. Circle 10 on Reader Service Card Larry Zide Publisher John M. Woram Editor Mark B. Waldstein Associate Editor Kathy Lee Advertising Production & Layout Carol Vitelli Classified Advertising THE SOUND ENGINEERING MAGAZINE Lydia Calogrides JULY 1981 VOLUME 15, NO. 7 Book Sales Eloise Beach Circulation Manager Bob Laude Art Director K &S Graphics Graphics Spartan Phototype Co. 28 Typography EDITORIAL THE AUDIO CONTROL OF LASER DISPLAYS 30 Lowell Cross DYNAMIC PROCESSING 42 Nigel Branwell sales offices THE CHANGING ART OF 47 Roy McDonald Associates, Inc. COMPOSING AND RECORDING Dallas, Texas 75237 Tom Lubin First Continental Bank Bldg. 5801 Marvin D. Love Freeway A db APPLICATION NOTE: 50 Suite 303 GETTING THOSE EFFECTS BOXES TO BEHAVE (214) 941 -4461 Joel Silverman Denver, Colorado Area Englewood, Colorado 80112 THE MATHEMATICS OF THE MICROPHONE, PART II 52 14 Inverness Dr. East, Bldg. 1- Penthouse John M. Woram (303) 771 -8181 Houston, Texas 77036 6901 Corporate Drive, Suite 210 (713) 988-5005 LETTERS 6 Los Angeles Area Glendale, California 91204 CALENDAR 14 424 West Colorado Street, Suite 201 (213) 244-8176 THEORY AND PRACTICE 18 Portland Area Norman H. Crowhurst Hillsboro, Oregon 97123 510 South First DIGITAL AUDIO 22 P.O. Box 696 Barry Blesser (503) 640-2011 San Francisco Area NEW PRODUCTS AND SERVICES 55 Emeryville, California 94608 265 Baybridge Office Plaza NEW LITERATURE 57 5801 Christie Avenue 58 (415) 653-2122 CLASSIFIED Sagamore Publishing Co., Inc. PEOPLE, PLACES, HAPPENINGS 60 New York Plainview, NY 11803 1120 Old Country Rd (516) 433 -6530 S is listed in Current Contents: Engineering and Technology ABOUT THE COVER In case you don't immediately recog- nize it, our cover illustrates a real -time. kinetic X -Y plot of the delay interval of db. the Sound Engineering 1l ago/ nc (ISSN 0011 -71451 is published monthly bs Sagamore Publishing Company. Inc. Entire con- tents cups right 1981 Is) Sagamore Publishing Co.. 1120 Old Country Road. Plain, ieu. L.I.. N.Y. 11803. l èlcphone15I61433 6530. a slowly swept sine wave. thanks to Our db is published for those indi, id uals and firms in professional audio- recording. broadcast. audio -, isual. sound reinforcement. con - Lowell Cross for the photo. and for his sultants.,idei, recording. Iiim sound. etc. Application should be made on the subscription form in the rear of each issue. Subscrip- feature story on The Audio Control of tions are $15.00 per year 1528.00 per year outside L.S. Possessions: $16.00 per year Canada) in C.S. funds. Single copies are 51.95 each. Editorial. Publishing and Sales Offices: 1 120 Old Country Road. Plain, icu. Neu York 1 18113. Controlled circulation postage Laser Displays, in this issue of db. paid at Plain, icu. \Y 11803 and an additional mailing ollicc. Ut Index of Novi you Letters Advertisers ear it... Altec 25 Ampex 35 MORE FEEDBACK ON THE Audio & Design Recording 29 DIGITAL QUESTION Audio -Technica 7 Bose 13 To THE EDITOR: Cetec Gauss 22 Re: The digital/ analog controversy. In Crown 11 the past 25 years, each major new elec- Electro -Voice 19 tronic development to be utilized by the ESE 51 audio industry was accompanied first Garner 6 by a setback in sound quality. and then ICC Business Research 17 by gradual improvement. After approxi- Inovonics 26 mately IO years of improvement, the new JBL 21 development eventually gained wide- Klark -Teknik 16 spread acceptance, even by the "golden Knowles 14 ears." Mike Shop 10 For example, in the 1960s one of the Model 105 M flab 20 first companies to convert to (discrete) Orban 27 transistor technology was Langevin. Otari Cover IV That company's first transistor products Pioneer 23 were very harsh sounding and prone to Polyline 57 failure as well. In their rush to be the Pro Audio System 12 é audio industry "firsts," Langevin did Roland Corp. 31 not survive the transistor revolution. liThe Garner Audio Tape De- Sescom 57 Between 1960 and 1970 (and beyond), Shure Cover II are truly the most gaussers the quality of transistors and transistor Sound Technology 36 37 flexible and thorough audio circuits improved enough so that the Soundcraftsmen 27 tape erasers available. With them, subjective "sound" of the mixing boards Standard Tape Lab 53 you can erase cassettes, reels, of that era eventually became quite good. Telex 15 and cartridges in just four The "tube" holdouts were fewer and Telex Turner 8 seconds. And, we guarantee fewer as the years went on. 3M Cover Ill that your erasure will meet the In 1969 approximately, Melcor came TOA 32 33 most stringent recording out with the first (discrete yet modular) Ursa Major 16 plug -in opamp. RCA, Automated Proc- Valley People 9 standards. It really is a case of esses, and Aengus, among others, were Yale Radio 18 "Now you hear it... the first to use these opamp modules Now you don't." exclusively in their consoles. The sound of these opamps was not bad, yet to my ears they were harsh to the extent that high- frequency brass instruments (espe- cially muted trumpets) came out sound- ing edgy and fatiguing. (Shades of Dr. Diamond ?) Note that Melcor and Aengus are no more, and Automated Processes exists in a highly -altered state (somewhere in Georgia, perhaps ?). GARNER INDUSTRIES, INC. Anyway, today, Deane Jensen has 4200 No. 48th St.. Lincoln. Nebraska 68504 designed retrofit plug -in Opamp modules Phone (402) 464 -5911 for the Melcor and Automated Processes products whose sound literally runs rings around the old sound. In ten years again, a fabulous improvement has taken There's more place. Another development, also around Coming 1969, was the integrated circuit opamp. to hear... Everyone rushed to put 301s and 741s Next Just write Garner Industries for into their consoles. Today those same Month more information: people are considering replacing the old ICs with high -speed Bifet replace- NAME - -- ments- because they too sound much In August, our featured topic is loud- better. speakers. For readers who are not satis- TITLE /POSITION - -- Similar events occurred with the fied with store -bought systems. author advent of the VCA and recently trans - John Hoge goes through the mathe- COMPANY formerless input (and output) amplifiers. matics of do- it- yourself design. And It is noteworthy that one British manu- URE1's Dean Austin describes some re- ADDRESS facturer of consoles, highly respected design problems (and their solutions. of for their sound quality, continues to course) the company faced as it updated CITY STATE ZIP avoid integrated circuits. opamps. its 800 series of studio monitors. And. VCAs. and FET or CMOS switches in as a change of pace. Sidney Silver re- L ----------J their console audio chain. turns to tell us about digital filtering. Circle 24 on Reader Service Card Pick a number from ATM11F 9 to 52! You've just chosen the ideal DC voltage to phantom -power these new ATM electret microphones. ATM91R AT8501 Introducing four "universal" phantom -powered electret microphones. Designed to work from external power, internal regulation automatically handles any voltage from 9 to 52 VDC without adapters. switches, or rewiring. Just plug in and enjoy. With current drain a mere 0.3 mA at 9 volts (4 mA at 12 -52V) a 9V battery lasts thousands of hours, not just the 60 or 70 hours typical of other mikes. When your power supply isn't available, or isn't enough, use ours. The new AT8501 Dual Battery Supply holds two 9V batteries. One to use, and one in reserve. Instant switchover and test LED eliminates guesswork. And spares are as near as the closest shopping center. Neat! But convenience and versatility are just two of the advantages of the new ATM models. All -new electronics provide plenty of headroom inside the microphone with no more than 1 rk THD even when used in a:oustic fields of 141 dB SPL. Which sets new standards for clean sound even close -up to big brass of inside a powerful drum kit. And the sound you hear is wide -range and musical. Presence without peaks. Highs to 20,000 Hz but without a raspy "edge" Yet despite their responsiveness, these new ATM microphones have the "Road Tough" reliability proved so often on stage and in the studio. audio-technicay. Before you add another microphone, compare our sou-ld, our convenience, our reliability, and our cost. Write for literature and list of nearby ATM microphone specialists. Get great sound...right from the start! AUDIO -TECHNICA U.S., INC., 1221 Commerce Drive, Stow, Ohio 44224. (216) 686 -2600. Circle 30 on Reader Service Card All of these devices are undergoing constant development and improvement. Is it not going to be the same with digital Desk Paging? audio? For example, at present, no digital recording system can meet the slew rate and power bandwidth specifica- tions of an NE5534 opamp. Slew rate ic4 and power bandwidth go hand -in -hand. with, in my opinion, audio quality. The same golden ears who kept us with tubes until the late '60s, and discrete transistors until just about now (when the quality of IC opamps is almost uni- versally accepted), will hopefully keep an eye (and an ear) open to the sound of digital.