Db Magazine, 1120 Old Country $14,500

ES ti CO' '''45

THE SOUND ENGINEERING MAGAZINE FEBRUARY 1976 $1.00

IN THIS ISSUE: The Whites of their Eyes Dynamic Control Of Sibilant Sounds Psychoacoustics

+.a*£4:,:. : . . , ttr - Next best thing to a sound proof booth.

Shure's new headset microphones are coming through loud and clear. With their unique miniature dynamic element placed right at the end of the boom, Shure's broadcast team eliminates the harsh "telephone" sound and standing waves generated by hollow -tube microphones. The SM10 microphone and the SM12 microphone /receiver have a unidirectional pickup pattern that rejects unwanted background noise, too. In fact, this is the first practical headset microphone that offers a high quality frequency response, effective noise rejection, unobstructed vision design, and unobtrusive size. Shure Brothers Inc. 222 Hartrey Ave., Evanston, IL 60204 In Canada: A. C. Simmonds & Sons Limited WA SI-IUFRE Manufacturers of high fidelity components, microphones, sound systems and related circuitry.

Circle 10 on Reader Service Card month The coming of spring is tradi- 0 0 tionally celebrated in song. So, what is good enough for Mendelssohn is THE SOUND ENGINEERING MAGAZINE good enough for db music is our ... FEBRUARY 1976, VOLUME 10, NUMBER 2 March theme.

Inventor Harald Bode provides a richly detailed explanation of FRE- QUENCY SHIFTERS FOR PROFESSIONAL AFPt.ICAT1oNs. of special interest to those who arc into electronic music. 20 THE WHITES OF THEIR EYES Marc Saul discuses methods of Martin Dickstein testing for harmonic distortion in musical reproduction in UNDERSTANDING 25 PSYCHOACOUSTICS HARMONIC DtsroRTIoN. Daniel Queen

Another lesson in Feedback comes 28 SCIENTIFIC CALCULATORS from Norman Crowhurst, the third in Philip C. Erhorn a series. 33 THE DYNAMIC CONTROL March will also bring the first article OF SIBILANT SOUNDS in a valuable series by Patrick S. Fin- Sidney L. Silver negan of Broadcast Audio. Mr. Finne- gan has spent a long career in broadcast audio engineering and we're sure 2 INDEX TO ADVERTISERS you'll lind his expertise of interest. His first article will cover broadcast 4 LETTERS stereo separation. 6 FREE LITERATURE

8 THEORY AND PRACTICE Norman H. Crowhurst 12 THE SYNC TRACK John Woram 14 SOUND WITH IMAGES Martin Dickstein 16 NEW PRODUCTS AND SERVICES 17 CALENDAR 37 CLASSIFIED 40 PEOPLE, PLACES. HAPPENINGS

db is listed in Current Contents: Engineering and Technology

Robert Bach Larry Zide PUBLISHER EDITOR Bob Laurie John Woram ART DIRECTOR ASSOCIATE EDITOR Eloise Beach Hazel Krantz CIRCULATION MANAGER COPY EDITOR Lydia Anderson Ann Russell ASST. CIRCULATION MANAGER PRODUCTION GRAPHICS Crescent Art Service

Painstakingly researched figures db. the Sound Engineering Magazine is published monthly by Sagamore Publishing Company. In Enlirr bring history in the -media contents copyright r 1976 by Sagamore Publishing Co., Inc.. 1120 Old Country Road. Plainview, L.1., N.Y. to life multi 11503. Telephone (516) 433 6530. db is published for those individuals and firms in professional audio. presentation of "The Battle of Bunker recording, broadcast. audio -visual, sound reinforcement, consultants. video recording, film sound. etc. Appli- cation should be made on the subscription form in the rear of each issue. Subscriptions are $7.00 per year Hill" produced for the Bicentennial in ($14.00 per year outside U. 5. Possessions, Canada, and Mexico) in U. S. funds. Single copies are 51.00 each. Controlled Circulation postage paid at Harrisburg, Pa. 17105. Editorial. Publishing. and Sales Offices: Massachusetts. 1120 Old Country Road. Plainview. New York 11803. Postmaster: Form 3579 should be sent to a hove address. 1 =gets

Audico 13 Audiotechniques 11 B &K Instruments 31 Bose Corporation 23

Brigham Young University . 18 Broadcast Electronics . . . 10 California Switch & Signal 12 Communications Company 6

Crown International . . . 7 dbx, Inc 9 Electro -Voice Cover 3

Garner Industries . . 14, 19 Infonics 6 Interface Electronics 12 Lexicon 2 Modular Audio 19 R. A. Neilson Co 16 Ramko Research 3 Recording Supply Corporation 14

Shure Brothers . . . Cover 2 Sound Workshop 35 Sparta 15 Standard Tape 4 Willi Studer America . . 27

TEAC Corp. of America . Cover 4

Telex Communications . . 5 White Instruments 4 P Woram Audio 18 Our V Heinz Hall for the Performing Arts, sales offices second - Pittsburgh, o o a Delta -T THE SOUND ENGINEERING MAGAZINE generation installation. New York 1120 Old Country Rd. delay system is Plainview, N.Y. 11803 516- 433 -6530 first in sound reinforcement Roy McDonald Associates, Inc. Dallas Stemmons Tower West, Suite 714 Which should come as no surprise. After all, Lexicon pioneered the first Dallas, Texas 75207 214- 637 -2444 all- electronic audio delay system. Now our second -generation Delta -T 102 is the digital delay system most specified by acoustic consultants and Denver leading sound contractors. They find the Delta -T 102 System significantly 3540 South Poplar St. improves the intelligibility and naturalness of sound reinforcement installa- Denver, Colo. 80237 303 -758 -3325 tions by acoustically synchronizing sound from multiple speaker locations. in The modularity of the Delta -T 102 allows the ultimate system flexibility. Houston Proprietary digital techniques give such important advantages as 90 dB 3130 Southwest Freeway dynamic range and 0.2% total distortion. A five -position LED headroom Houston, Tex. 77006 713 -529 -6711 indicator with 40 dB range assures straightforward and simple level setting. These systems are easy to install and extremely reliable. Most important, Los Angeles they are the best performing digital delay units available today at any price. 500 S. Virgil, Suite 360 To get the full story, circle reader service number or write Lexicon, Los Angeles, Cal. 90020 213- 381 -6106 Inc, 60 Turner Street, Waltham, Massachusetts 02154. Or call 617- 891 -6790. Portland 2035 S. W. 58th Ave. Portland, Ore. 97221 503 -292 -8521 Write on your letterhead for free 14 -page application note. exicon AN -2. on sound reinforcement. San Francisco 60 Tur ner Street Suite 265, 5801 Christie Ave. Waltham, Massachusetts 02154 Emeryville, Cal. 94608 415 -653 -2122 N 1617) 891 -6790 Circle 12 on Reader Service Card Our new E series audio equipment will improve your sound and cut your costs ... or your money back!

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TURNTABLE PREAMPS power supply, metering & headphone Winders also come in higher speed models (ACL - Preamps costing almost 3 times more will not corn. monitor. Will accept up to 10 slide in 60 series). Same operation as above but winds at pare with these units. RIAA /NAB equalized ±1db, modules. Each module has 2 inputs 60 IPS. Accepts 14" pancakes. & B 0.5MV sensitivity at 1KHz for 4-4dbm out, balanced outputs. Individual output level ACL- 60T, "E (tone stop only) $266 outputs, controls & selectable meter switch. Up -75db s/n at 10mv in, 0.05% distortion, ACL -60B /E (Blank tape loader) 5331 21dbm max. out. Internal power supply. to 20 in /80 out. ACL- 60BT /E (for both prerecorded and MP -8E DA- 2080/E Main Frame $150 Mono 586 SP -8E Stereo 5137 blank tape) S375 DA- 2080/E Modules 2 in /8 out $135 ea.

MIC & LINE AMPLIFIERS STUDIO MONITOR AMPLIFIERS AUDIO CONSOLES Sr CONTROLLERS Dual function and superb performance. Inputs for Exceptional reproduction! Internal muting. ±2db Our new series 35 audio controller introduces a mic and line, +05db response 10Hz- 20KHz, 67db response from 20Hz- 40KHz. 25w music power, 20w gain on mie channel(s) -I 26db new concept in audio mixing. Allows separation of gain on line inputs. RMS into B ohms. Hum & noise 65db below rated ... controls from the audio functions. Controls can be Balanced inputs & outputs, 21dbm out max, 0.1% outputs. distortion. Internal power supply. placed in any convenient location in the studio, while electronics may be mounted anywhere for Distortion less than 0.25% at less than 20w out, MEA -1E Mono 598 easy maintenance & hookup. Remote DC control 1% or less at 20w. Works into 4- 16ohms. Balanced MLA -2E Dual Mono /Stereo $139 for completely unaffected audio. bridging inputs, variable bass contour, internal overload & short circuit protection. This versatility gives you a custom designed con- AUDIO DISTRIBUTION AMPLIFIERS sole at a standard production model cost. SMA -50 /E Table top (mono) 5125 Features include; B channels, mono, SMA -500,E Rack mount (mono) $142 from 1 in /6 out to 20 in,'80 out in one small pack- dual channel age. Whatever your distribution requirements we mono, stereo, dual channel stereo, or combina- SMA -1000 /E Rack mount (stereo -40w) 5196 have an answer. All units meet or exceed the fol- tions; paralleling 2 units for quad, fail safe power lowing specifications: Balanced bridging /matching supply & plug in interchangeable cards. REMOTE POWER CONTROLLERS (DUAL) inputs, balanced (r00ohm outputs, ±0.5db re- Performance specifications are; 0.3% or less dis- sponse 10Hz- 20KHz, ± 3db 5Hz- 40KHz, 26db gain, tortion, 124dbm equivalent noise on low level chan- Safe, transient free means of controlling 110V /AC. -21dbm out. max. capability, 0.1% or less distor- nels, approximately 25w power consumption, Turntables, on the air lights, etc. tion, outputs isolated by 80db, hum and noise 90db -70db crosstalk, balanced bridging /matching in- PR -2 (toggle switch on /off) $39 down referenced to -21dbm out. Internal power puts & response within 4-2db 20Hz- 20KHz. Series i PR -26 (momentary contact actuation) $54 supplies. 35 audio controllers start at $1200.

DA-6/ E Table top. 1 in /6 out. 5131 Give us a call or write today for further details. AUTOMATIC TAPE CARTRIDGE AND CASSETTE DA-6R/E Rack mount. I in /6 out. $149 You'll be and LOADERS money performance ahead. DA-6812/E Rack mount. 1 in /6 out. Individual to level controls for each output. 516; So easy use & accurate that our largest winder competitor has been using one of these to load CALL COLLECT (916) 392 -2100 DA -6RS 1 - /E Rack mount. in /6 out stereo or 2 their own carts. in /12 out WRITE 3516 -C LaGrande Boulevard mono. 5229 Eliminates guesswork. Set the dials to the length - Sacramento, DA- 16BR /E Rack mount. 1 in /8 out stereo or 2 desired. The exact amount of tape is fed onto the California 95823 in /16 out mono. Individual output cart or cassette hub and then shuts off automatical- level controls, selectable metering & ly. Also has exclusive torque control for proper headphone monitoring. 5287 tape pack on different size hubs. Winds at 30 IPS. RESEARCH DA- 2080 /E Rack mount main frame with protected ACL -25/E 5185 RAMKO

Circle 13 on Reader Service Card You're letters in THE EDITOR: Good Very good article on black boxes in the July issue -let's have more of them. I have a few comments which when you use may be helpful to others. Amen to always checking for d.c. Even though STL magnetic Test Tapes I knew about it and had run into it before. I still managed (by persistence STL magnetic test tapes are widely used by major recording and stupidity) to blow a power transformer instead of just fuses when my studios, equipment manufacturers, government and "handy shirtpocket tester was at the educational agencies throughout the world. The most bottom of my bag and I was in a comprehensive test tapes made they are offered in 1" and hurry. I have since modified all my 2" sizes as well as flutter tapes and all other formats. multi -outlet strips by prying the jewel off the neon lamps so both electrodes You know your is in system step with the rest of the are clearly visible and I always check industry, compatible and interchangeable, when you first to see that both light before plug- employ STL tapes, the most accurate reference available. ging anything in. (By the way, you say filaments in your article. Neon Write for a free brochure and the dealer in your area. lamps have no filaments. but rather, electrodes.) Distributed exclusively by Taber Manufacturing & Engineering Co. Thanks for clearing up what is inside of the cable tester boxes. I had seen one at a radio station and it UJFISTANDARD TAPE LABORATORY, Inc. seemed to be such a good idea, I built 208 Edison Avenue one when I got to the shop. Since I San Leandro, CA 94577 didn't know what should be in it and (415) 635 -3805 I had only had a quick look. I built my own (see figure) I used two AA

CABLE Circle 14 on Reader Service Card

3v R(L3)

NEW AUDIO SPECTRUM MONITOR! 11 1 .2 II S 1/3 OCTAVE REAL TIME ANALYSIS MODEL 142

PEAK READING TWO MEMORIES: CUMULATIVE OR SAMPLE 3 3 VARIABLE TIME CONSTANTS (0.1 - 2 SEC.) CALIBRATED IN HOME BREW CABLE TESTER to 16 1/3 FEATURES DBM 10 -20 -30 DB DISPLAY RANGE 40 HZ KHZ ON penlight cells and for L, and L, I OCTAVE ISO CENTERS 11 x 28 LED ARRAY BUILT -IN PINK used two "grab bag" leds. which gave NOISE SOURCE 31/2" x 8" DEEP RACK MOUNT. a good brightness, was somewhat com-

PROGRAM MATERIAL MONITORING RECORDING AND MIX - parable to current at line level, and DOWN ANALYSIS PORTABLE SYSTEM ADJUSTMENT TAPE resulted in an acceptable current when USES EQUALIZATION AND CALIBRATION TRANSMISSION LINE one led was shorted out by a had cable. EQUALIZATION BEFORE -AFTER COMPARISONS FREQUENCY I found that R could he replaced by TESTING RESPONSE L. a low current 3V bulb (nor a flash- light bulb). If a cable is good, both leds light (L., is too dim to see). If only one led lights or if none light and L., shines brightly. I know there is either a polarity reversal or short in the cable. (I could make up a table of what means what, but I made the box only for quick cable checks.) While I was at it, I also used another led rigged in a similar manner through L. and two -pin jacks to check out Suggested patch cords, speaker cables. etc. List Price $3200 Yes, always carry phase reversers, but don't buy them. They seem rather a short ALSO: Active and passive equalizers Other real time analyzer$ overpriced to me. Just make Dealer inquiries invited extension cable and reverse the wires between pins two and three. Even in- Call or write today: WHITE INSTRUMENTS, INC. cluding labor, it's half the price. R,4,6C, P.O. BOX 698 512/892 -0752 Austin, Texas 78767 DONALD WADE Jackson Heights, N.Y. Circle 15 on Reader Service Card quarter track configurations, has proof tape handling gentle fail safe differential brakes and enough for half mil tape. And Old-New accepts 8% inch reels. It also still new electronics, clean to 60 dB comes with three motors -but S/N at all speeds. Reel Time then, that's touching on the new. If you're looking for a real time, The New. A brushless d.c. servo reel recorder with old name reli- drive with a crystal oscillator con- ability but designed for today's Recorder trol reference so accurate it vir- demands, you'll find it in the tually eliminates program timing Telex /Magnecord series 1400. Telex /Magnecord series 1400 errors. New, three speeds: 33/4 - For complete infor- broadcast quality recorder /re- 7% - 15 ips. New catenary head mation please producer. An old name that spells block for straight tape loading, write: reliability. A new design for to- the convenience of one hand day's state of the art. cueing and the bi -level illumina- The Old. Telex /Magnecord tion of push button controls. products are still made in the New DTL logic controls USA so parts and service are eliminate EMI and always available. The series 1400 provide fast, is still built on a solid die cast spill aluminum main frame for reliable operation around the clock. It's still available in full, half and

TELEX.PRODUCTS OF SOUND RESEARCH I I ' C O M M U N C A T O N S . I N C . 9600 ALDRICH AVE. SO. MINNEAPOLIS. MINN. 55420 U.S.A. Europe: 22, rue de la Legion- d'Honneur. 93200 St. Denis. France Canada: Telak Electronics, Ltd., Scarborough, Ontario

Circle 22 on Reader Service Card FREE LITERATURE ELECTRIC POWER OUTLET STRIPS MEASURE Electric power outlet strips and REVERB TIME wheeled carts are described in a four - page catalog. Mfr: SOL Waber Elec- IN REAL TIME. NEW PRODUCT DIRECTORY tric. A directory of manufacturers of a Circle 86 on R.S. Card. Instantly! wide assortment of industrial equip- HEAT SINK WALL ment and musical instruments, some CHART of which are applicable to audio inter- A 25 x 38 in. chart contains a heat ests, covers 20 pages. Mfr: Katy In- sink selection guide, featuring over 50 dustries. extrusions. Information includes sur- Circle 82 on R.S. Card. face area, weight, and thermal resistance. Mfr: Thermalloy, Inc. MINIATURE COMMUNICATIONS Circle 87 on R.S. Card. EQUIPMENT ANALYZERS Two -way communications equip- SPECTRUM RT-60. ment, with accessories, are described Measurement of distortion, fre- This easy -to -use in a 4 -page brochure. Mfr: Unex Lab- quency response, wow and flutter, sig- instrument delivers pre- nal -to -noise ratio, and cross talk with cise reverb time measurement in instant real time digital read- oratories. out. No more chart recorder or time- consuming chart re- Circle 83 on R.S. Card. low- frequency wave and spectrum corder analysis. The RT -60's integrated circuitry incorpor- analyzers is discussed in this I6 -page ates a one -third octave band pass filter system with frequency centers on 250,500.10002.000. and 4.000 Hz. It HOCKEY PUK RECTIFIERS booklet. Detailed graphs and copy operates on self -contained ni -cad batteries. Mounted in a cover audio equipment of all kinds as rugged carrying case, the RT -60 weighs only 3.5 pounds. A new line of 650 amp fast recov- The dealer net FOB is well as the various harmonics. Mfr: cost. San Diego. just $395. ery Hockey Puk silicon rectifiers is Write for your free technical Hewlett- Packard Co. bulletin on the R7 -60 instantly! described in this sheet. - data Mfr: In- Circle 88 on R.S. Card. ternational Rectifier. communicnmons Circle 84 on R.S. Card. CHANNEL CIRCUITS comPnnY RECORD CARE The intricacies of using channel circuits in wiring breadboard compo- Int. This is a six leaflet -page describing nents are explored in a brochure and 3490 Noell Street ways to protect records from deterio- specification sheet. Step -by -step wiring San Diego. CA 92110 ration through the use of record clean- Telephone (714) 297 -3261 of the boards, as well as descriptions ers. Mfr: Uher of America, Inc. of the various configurations are in- Circle 85 on R.S. Card. Circle 17 on Reader Service Card cluded. Mfr: Chanex, Inc. Circle 89 on R.S. Card.

EQUALIZER MICROPHONE E Qualidyne T`t a microphone that COMMERCIAL DUPLICATING SYSTEMS includes equalization and feedback control, is described in a four page booklet. Mfr: Shure Bros. INSTALLATION AND PREVENTIVE Circle 90 on R.S. Card. MAINTENANCE TRAINING AMPLIFIER OVERLOAD A two -page application note dis- INCLUDED IN PRICING cusses amplifier overload and recovery time. In addition to general informa- Mid Atlantic Service Center tion, the application note illustrates CASSETTE SYSTEMS typical problems with a block diagram and waveform sketches. 199 Davis Avenue Circle 91 on R.S. Card. Woodstock, Md. 21163 TABLE TALK NO. 8 Phone: (301) 922 -8865 What Happens to Your Film at the Lab, part 3 - The Optical Sound Track, is the title of a brochure which AL di explains in narrative form and with extensive detail exactly what happens to a movie film when it is processed. The article contains valuable tips for getting the most out of film. Mfr: Motion Picture Laboratories, Inc. Circle 92 on R.S. Card.

DISCOTHEQUE SYSTEMS A A series of brochures details a com- PHOENIX plete line of equipment needed for ENTERPRISE discotheque audio production. Mfr: COMPANY DISCOtheque Time Service. Circle 93 on R.S. Card. Circle 18 on Reader Service Card ßäc a

If there's one thing you need in commercial sound components, it's reliability.

Consider this. We believe the Crown DC -300A amplifier to be so care- 8 ohms.* You can drive a 70 -volt balanced line directly fully crafted, so well- designed, and so thoroughly in- without installing a matching transformer. spected, that for three years after purchase, if it doesn't Another good reason to specify the DC -300A is the al- work as specified, we will replace any defective part at most absolute purity of its sound. When Crown intro- no cost to you. We will also pay U.S. round -trip shipping duced the DC -300A some years ago, the audio world costs (the DC 55 -300A weighs pounds) on units requiring recognized it as a significant improvement in low service. distortion and noise levels in a commercially practicable It should be obvious that we can offer such a warranty amplifier. At its rated output, IM and harmonic distortion only because we have convinced ourselves that you are less than .05 %, 1 Hz to 20 kHz, and hum and noise probably won't need it. Crown builds the DC -300A to are 110 dB below rated output. Frequency response is work - and to keep on working. It is reliable. ±.01 dB, 1 Hz -20 kHz @ 1 watt into 8t2. Consider further the output protection built into the Reliability, power and high -fidelity are three good rea- DC -300A. Shorts, mismatches, open loads, all have no sons the DC -300A should be in your next sound system. effect on the DC -300A. even drive The amplifier will There is one other reason. totally reactive loads without damaging itself. Massive black- anodized heat sinks are thermally joined with the The Crown name. chassis to utilize the entire amplifier for efficient heat Crown people believe, as an article of their faith, that dissipation. manufacturers have a responsibility to tell the exact truth The Crown DC -300A could easily be the most reliable, about their product so far as it can be determined. As a service -free major component in any sound system. result, any well- equipped laboratory should be able to test any Crown amplifier, and report test figures that are But there are other good reasons for specifying the DC- as good -or better -than the figures reported by Crown 300A. in its advertising and specifications. One is the large amount of power available. The DC -300A That's reliability. Crown reliability. is rated at 155 watts per channel (both channels operating) into 8 ohms. Or 310 watts per channel into 4 For detailed specs on the DC -300A, write us or call ohms.* or 500 watts per channel into 2.5 ohms.* 219/294 -5571. In the mono mode, which involves only one simple wiring *Single channel operating; sine wave test signal into resistive load; DC extended operation or restricted air flow may require forced air change, the -300A will produce up to 600 watts into cooling to maintain levels described.

When listening becomes an art, crown Box 1000, Elkhart IN 46514 Circle /9 on Reader Service Card Presumably another reason for going through all that theory was so that you would note the various places where certain parameters were assumed to be small enough to be negligible and thus realize that when they are not, the conclusion derived from that assumption is no longer true. But

Recently I have been receiving and college level, for showing students if you are going the memory route, more than the usual number of letters how to do something, like solving that is an awful lot to remember. It from readers, asking how, or where, equations, without bothering whether is so much better if you can really they can get courses in audio that will they understand it, or perhaps not understand the basics. prepare them for a creative career in even letting them understand it? The The trouble is, it is extremely diffi- audio work. Some, realizing the short- same goes for this approach into solid cult even to get at the basics, much age, ask how the "college of their state theory. less to understand them, when you choice" could be induced to start So, after taking the course, the stu- have to plod through all that suppos- something that would provide such a dent can write down the relevant for- edly basic theory. So, maybe you ac- program. mulas for every solid state device in cept all that material, merely because a given schematic. For some of these it is required, but you find it of no WHAT ARE THE BASIC i.c. chips, that would be an encyclo- real use to you because it is impos- REQUIREMENTS? pedia full of formulas! But having sible for you to apply it. So you con- The very asking of this question, at written all that down, does he know centrate your real learning effort on the least in a college campus context, is how the chip works, or even know practical side -working at consoles, apt to entrap us into the wrong kind how to go about finding out how it making recordings, finding out through of answer. For in a university setting, works? trial and error what you do wrong, the words "basic requirements" carry I could give you some more exam- and so forth. a connotation of "what courses should ples of the same kind of thing, but I I take ?" So one starts looking down think that example is enough to make HOW TO GET THE REAL BASICS the catalog in question, to see what my point. What the audio man really I don't want to knock hands -on courses look appropriate. needs is the kind of know -how that experience of this type. It can be valu- As I am writing this, I happen to will enable him to go after precisely able. But what for? Are you learning have a fairly severe cold, an event that the information about solid state de- "how it is done ?" Or are you merely happens to me rather rarely. This con- vices he will need for the audio job getting the feel of how one particular dition occasions the need for fairly he may have in hand. Knowing all console does its job, or how certain frequent blowing of my nose. As I do that other stuff will be no help to him. specific effects are achieved? not have to do this very often, at least unless he can apply it to something a with the severity occasioned by a practical. There is considerable appeal to heavy cold, I get to wondering whether Of course, you also need back- student who wants to become a re- his I ever learned how to blow my nose ground on acoustics, transducers, mag- cording man and has never had properly? netic materials, electronics. and so hands on a console in the offer of "hands -on" as part the I was almost afraid to write that, forth. But, taking the first of these. experience, of for fear the next thing that appears must you always start with the course offering. And, of course, if that on college catalogs, all over the coun- D'Alembertian wave equation? If all is the basis for the students' choice, they feel the more hands -on the better. try, will be courses on correct nose - you ever learned about calculus was blowing technique! I still have vague how to do it. you don't really know What they tend to become, going recollections of kindergarten, or early what all those little incremental signs this route, is good "audio mechanics," grade teachers, showing small fry how mean, and can only copy down what rather after the style of the mechan- to blow their noses properly, and hap- the course -work showed you about ap- ics at many neighborhood service sta- pen to think that is the proper age to plying the equation through various tions. If they know precisely what they teach that kind of thing. "boundary conditions" to specific sit- have to do, they can do it, with vary- Let me take an item I see listed as uations that, at best, only approximate ing degrees of proficiency, according an ingredient in a proposed "audio the devices you are working with. to how good their hands -on experi- package" -solid state theory. Now, All that may be very impressive, to ence was. But give them something my bookshelf has about three feet of someone who doesn't "know all that they have not been shown, and they books on that topic. So I look through stuff." But does it really help you to are lost. them, to see which, if any, would give do a better job? What you need, far This weakness can apply either to a the best preparation for an audio man. more, is a feel or a way of visualizing, new type of console or to the produc- Most of them start out with the theory what happens to sound waves in the tion of a different type of program. of atomic particles and energy levels, kind of practical situation with which Unfortunately, while it may be much and plenty of equations that I am sure you will be working. more fun, in other respects, the hands - no audio man will ever get to use. Or perhaps you followed all through on approach, without the needed back- And yet I can see, and would my- that stuff for the purpose of memoriz- ground to go with it, is very much self insist, that a good audio man ing the conclusions derived at the end, like rote learning. You learn only needs to know how various solid state relating wavelengths to various acous- what you are shown how to do. devices can be used, in both analog tic effects, so you could apply the in- Perhaps it is relevant here, to com- (perhaps you know that best as linear) formation to your practical situations. pare this field with the one in which and digital circuitry, unless he planned The problem there is that relying on I have spent much more of my life, to have nothing to do with synthe- memorized conclusions can often (and engineering. I have always been de- sizers and electronic organs. usually does) overlook any limitations signing, or developing, something new, Remember how I have criticized beyond which those conclusions no that nobody has made before. Often co current math programs, at both school longer apply. I get the question, "Where did you ABC Recordin r -J2 W . Studios A.... :tir `W enjoy* 'Pr:IW t, noise -free recording with 88 channels dbx noise eliininatioq

Howard Gale at the Studio B console during session for the three Dog Night album Cumin' Down Your Way, A BCD 888. d6X Incorporated 296 Newton Street Waltham, MA 02154 Circle 20 un Reader Service Card theory & practice (cont.) a means of getting there. Some of the better ideas that have been incorporated into audio systems have origin- learn how to do that ?" Of course, I ated in the heads of men whose real had an engineering education, but the interest was in producing a different way the questioner asks it, makes it kind of sound. Maybe they put some- similar to asking Thomas Edison thing together themselves that the where he learned to invent the light hardware people later copied. More bulb (or any other of his numerous often, they had a good idea of what CONSOLE inventions). they wanted, and went to the hard- VERSA People who invent things are always ware people and said, "Can you make making "firsts " -something that no- me up a unit that will ..." and after body has done before -and thus there some back and forth, a new idea be- is nobody around to show them how. came fact. Can you imagine Edison going to the Are you getting a picture of what Compact rack-mount single channel mixer ideal for CATV, CCTV, local bookstall, to find a book, How creativity is, and more importantly, film studios and remote broad- to Invent the Electric Light? Had how it happens? So how do you go casts. Transformer coupled inputs with externally switchable levels. there been such a book, obviously about acquiring creativity? Line and PA outputs. someone else must have already in- It is a big help to try to simulate vented it, and Edison would have the creative activity of the past. In- 50 SERIES MONO been too late! stead of merely examining what some- Although the successful audio man body creative has already done-by may not be an inventor, in quite the then, it seems so obvious, so how come same sense, there is one respect in nobody has left you anything obvious which what he does, or should be able to do like that? -try to put yourself to do, is quite similar: he must be cre- in the creator's shoes. Supposing you Complete small console for production. on-air, educational or ative. He needs to be able to dream had not seen it done, how do you CATV use. 8 switch selectable in- up, and thus execute, "firsts." This think he would have come across the puts to four sealed mixers with cue detents. Built in muting re- means he is not copying what some- idea? For me to attempt to answer lay and monitor amps. Rack one else has shown him. that would destroy your effort. But in mount available. a classroom session, tossing ideas like 100/200 SERIES HOW TO ACQUIRE CREATIVITY this around can be helpful. MONO & STEREO Because a creative person is doing One thing is on our side; human be- what has not been done before, and ings are naturally creative, although because he never copies what some- sometimes that is difficult to believe one else has done, you might imagine because creativity has been so success- he works best alone, in isolation. While fully stifled by our educational sys- he must be capable of thinking alone, tem. But because this is so, a session Full dual channel consoles with beyond the lines of thought he has in which creativity is sparked is al- 5 or 8 mixers. Pushbutton se- already been shown, he also needs to ways an exciting experience -it turns lected inputs available to high or on. low level (switchable) plug -in pre - be vitally aware of what others are people amps. FET switching for quiet doing. As I am beginning to look at how operation. Dual channel outputs at over +18 dBm peak. Complete In the fiield of engineering, had much space is left this month, I want internal monitoring and muting someone working in isolation devel- to pass on to you some of the advice functions. Stereo models provide that Bill Putnam gave to last year's in -phase stereo from mono oped a Moog synthesizer, say a year or sources. two after Bob Moog did, would that BYU Workshop participants. He told SLIDE TYPE do him any good? Bob has all the pat- them how necessary the kind of basics ents on his way of doing it. The fact that we were giving them were, that CONSOLES that this second comer had done it as far as "hands -on" experience is con- independently, without actually copy- cerned, any good studio would rather ing Moog, would not make it original, have a man with little or no hands-on would it? Not in the patent sense, experience but long on creativity and anyway. do what training might be necessary Now that synthesizers have made it in the "mechanics" department, them- Available mono or stereo with into the world, via the brains of in- selves. plug -in mixers for expansion after purchase. Conductive plastic lin- ventors like Bob Moog, how is the Somewhere about the time you read ear faders with cue switch. Built best way for someone else to get into this, advance notices about this year's in muting, monitor and intercom/ talkback provision. the synthesizer business? Take a good workshop should be appearing. There look at various synthesizers on the will be prerequisite material available, market, and I think you'll get the idea. so you can come on campus, armed ALSO TAPE CARTRIDGE That relates to creativity in devel- with what you should know, to make MACHINES AND STUDIO oping hardware. Some of you are the very best of your time there. We ACCESSORIES more concerned with software -mak- are still working on how to get an ef- ing various kinds of records. But the fective program that will give more BROADCAST same principle applies. If you work in than is possible in a summer work- ELECTRONICS, isolation, you are apt to find yourself shop. But meanwhile, lots of past INC. the wheel." workshop participants have -A FILM WAYS COMPANY - "re- inventing summer - very they got a 8810 BROOKVILLE ROAD Just because your primary concern stretched what there be with software want to way, to become highly success- SILVER SPRING, MD. 20910 may -you long are slow PHONE 301 -588 -4983 produce some gold records -do not ful in the field. And they not O rule out any interest in hardware, as to give credit where it's due. Circle 21 on Reader Service Card Our system is hard to beat The all time favorite monitor system in U. S. recording studios is the Altec 604. Add our Mastering Lab frequency divider with its improved mid -range, distortion -free crossover and extended bass and you have a system that is truly hard to beat. We have packaged 604s and M/L dividers in a bass reflex enclosure and named them Big Reds. For super bass response and increased sound pressure level, we add an extra 15" woofer, plus a low frequency crossover and call them Super Reds. Use our M/L dividers to perk up your present 604s or go all the way with either of our Red systems and join the list of studios that benefit from monitoring with the Mastering Lab system. techniques,inc. 142 Hamilton Avenue, Stamford. CT 06902 Telephone: 203 359 2312

MASTERING LAB CROSSOVER USERS

A & M Recording Dawnbreaker Studio Graham Nash Springfield Sound American Recording Disney World Nimbus Nine Productions Sundance Recording Applewood Studios Dynamic Sounds Ochoa Recording Studio Sunset Sound A & R Recording Earth Audio ODO Recording Sunswept Studio Artists Recording Studio Falcon Records Original Sound Howard Schwartz Recording Atlantic Recording Studio Fanshawe College P & P Recording Sunchron Studios Audio Arts Good Times Studio Richard Perry TDF, Florida Autumn Sound Great Lakes Audio Pinellas Music The Guess Who Randy Bachman Hallmark Studios Producer's Workshop Toronto Sound Berklee College of Music Wally Heider, Los Angeles RCA, N.Y.C. United Artists Studios Black Crack Studios House of Music RCA, Los Angeles University of Mass, Boston Blue Rock Studios Intercontinental Absurdities Roade West Recording Valentine Recording Caribou Ranch John Kay Rockland Recording Vantone Studios Catholic University Kendun Recorders Salty Dog Studio Venture Sound Chariot Studio David Kershenbaurn Sigma Sound Village Recorder Cherokee Recording Mama Jo's Sound Exchange Western Recording Conway Recording Manta Sound Sound Factory Whitney Recording Dallasonic Recording Minot Sound Sound Ideas Davlen Sound MZH Studios Sound Labs

Circle 16 on Reader Service Card STAGE a:0 the sync JOHN M.W MONITORS

Every time I hear about a new gobo, bus, retentivity, quad. foldback audio book, I get a little sweaty, since and such. my own opus is just about ready to be You are in luck though if you were launched. To all those who have in- wondering about: quired, "When, where, how much, quack why ?," I'm delighted by your interest. -.short. loud, harsh, throaty sound such But, as they say in the publishing biz, as that made by a duck, or any similar sound. the book is "in production." At the (Duck is not moment, it depends on an assorted defined.) bunch of shady characters, such as Sneeze, yap, bray, bleat are similarly typesetters, proof readers, commercial covered, along with the rest of the artists, editors, and book binders. barnyard. After all, it is a dictionary When -and only when -these folks of sound. are done with work, their foul the In all. 3.556 terms are defined in book will be ready. My astrologer English (and numbered). Each defini- tells me this will be about the time of tion is followed by the translation of the spring thaw. I means suppose that the term (but not of the definition it- sometime in May, 1976, who but self) in Dutch, French. German, Ital- knows -it could be earlier or later. As ian, Portugese, Russian, and Spanish. for the price, it will have to be suffi- The definitions take up about two to all ciently outrageous take care of thirds of the book. The final third con- these hangers -on, and their insatiable tains alphabetical listings of each term INTERFACE ELECTRONICS appetites. 10WESTHEIMER HOUSTON. TESeS 77027 17131 626.1190 in the seven languages just listed. In the meantime, I suggested to our Here, each term is keyed to the ap- esteemed editor that he review those propriate definition number. For ex- Circle 23 on Reader Service Card other books and write scathing re- ample, the Russian speaking engineer views. You'd think that would be the may look up OCHOBRA and find that least he could do. Well, he liked the it is definition #0355. Turning quickly basic concept, but seemed to have to 0355, he finds the English defini- some of reservations law- STOP sort about tion of base. Now he's got to under- suits and other types of unpleasant- stand English to get anything out of ness. So, I shall have to do it myself. it. But, if he understands English, why How typical. 1"' CABLE look in the foreign language section in the first place? Of course, it would be THIEVES INTERNATIONAL DICTIONARIES /l unreasonable to expect a complete OF SCIENCE AND TECHNOLOGY: definition in each of the seven lan- IDENTIFY SOUND -R. W. B. Stephens, editor. guages, and I realize the cross refer- //// Halsted Press, div. of John Wiley & ence will be valuable for the bi- or /j YOUR CABLES Sons. 853 pages ($37.50). multi -lingual who be brio engineer may not "Coverage includes ... an exhaus- familiar with the English equivalent of tive treatment of topics like architec- a particular term in his native lan- tural acoustics, audio circuits. disc, guage. Or, he may wish a cross refer- magnetic, and optical recording, sound ence of terms from one language to editing...." (from the flyleaf). another. Thirty seven bucks,!!? for a BOOK? But, this is a lot of space to devote As Ed McMahon would say, "Isn't it to the needs of such a small percent- amazing that for a mere $37.50, age (I think) of readers. Perhaps this they've given you everything you need should have been a two volume set: to know about all those subjects ?" Volume One a more thorough diction- Well, it would be impressive indeed ary- Volume Two a multi -lingual if it had lived up to its promise. Just PRO SOUND I.D. collars protect your cross reference available for those sound cables against theft, allow you to think of a book that would define the who require such a tool. color code cable lengths and quickly iden- gauss and the oersted, and clarify the tify your property. Hot stamped with two lines of copy also advertises your business meaning of the dBm, dBV, and the or group. Available for 3/8" and 1/4" VU. Or is it vu? V.U.? Maybe v.u. FREE -WHEELING DEFINITIONS cable in five colors: blue, red, yellow, white and black. Write for data or call: Bad news, folks. Gauss is listed, As to the terms that are defined, oersted isn't, although the latter term many leave something to be desired. is found within the definition of the For example, there are definitions of former! Decibel is briefly defined, but free -field conditions, free -field correc- bUflb" there is no mention of dBm, dBv, etc. tion, f-f current response, and so on, P.O. Box 91798, Los Angeles, CA 90009 Sel -Sync and overdub are not to be but no definition of free -field itself. If 1213) 776 -5445 found. Neither are inertance, fluxivity, you think to look up free -field room, Circle 24 on Reader Service Card it says, See atechoic room. There, it the reader can understand what is says, Room lined with sound absorber, being said, and why. having sufficient absorption to enable a In Chapter 8, Equalizing the Sound .sound field free from objectionable System, we learn what sound system LOAD UP reflections to he produced, enabling equalization is and what it is not. Ap- free -field measurements to be made. parently Mr. Davis takes a dim view Reading between the lines, one gets of those who think of it as a means the idea that a free -field is an area in of covering up all the little atrocities which there are no interference-pro - that have been misdesigned into the AND SAYE ducing reflections around. system. Directional characteristic. Charac- If the equalizer in out switch makes teristic of a microphone, expressing the unlikely change from total unintel- the degree by which the sensitivity is ligibility to startling clarity, one may at 135 ips ,greater in n particular direction. Huh? safely have second thoughts about, a) What does degree mean, angle or the design of the sound system, b) the amount? And what about the direc- design of the room, or c) both. tional characteristic of a loudspeaker? That can he found under Directivity MATERIAL FOR BEGINNERS Pattern. Subsequent chapters cover Instru- On the other hand. anatomical terms mentation, Sample Design Applica- are clearly defined. ( Incus, mallets, tions, and Specifications. This latter stapes, et al). There are also good de- chapter should he of particular inter- finitions of some musical instruments. est to the beginning sound system spe- (Drum and base drum are in, though cialist who needs some guidance in snare drum and tom -toni aren't.) getting his act together. Load your own and save ... with bulk tape, C -O cassettes and the Audico In short, this hook is not for every- The book concludes with eleven ap- Cassette Loader. No waste tape, no one. Some of the definitions will sail pendices. There's an excellent section post -tailoring, less handling of tapes. right over the heads of many readers. on Recommended Installation Tech- Cut materials cost and inventories in Others take a hit of detective work to niques, showing both how to, and how half. figure The hook is not to wrap, out. itself elegantly tie, terminate and solder. 751 Cassette Loader produced, well hound, clearly printed, And just to make sure you've been Loads a C60 in 25 seconds and with excellent illustrations. I hope paying attention, the last two appen- Extremely accurate: Absolute repeatabil- there will eventually he a second edi- dices are a series of test questions and ity to ± 2" tion, with the necessary revisions. We answers. Safely handles C120 stock could certainly use it. In the mean- All in all, this is a welcome addi- Digital Lock 0 Tone available time. I'd suggest looking the book over tion to the attdio man's bookshelf. carefully before buying it. MUSICAL ENGINEERING SOUND SYSTEMS ENGINEERING For odd jobs try this by Don and Carolyn Davis. Howard However, if you want a little some- Sams & Co. 295 pages ($19.95). thing more than a book or two, how about a four -year degree granting versatile utility winder Now here's a hook of a different course in Musical Engineering? The color (yellow, as a matter of fact). curriculum would include courses in Author Don Davis is well known for music his work in sound systems engineering, theory and practice, electronics. acoustics, and recording techniques. and I believe this book is used as a And when you graduate you do) text in his Sm -Aud -Con lecture series. (if The book addresses itself to the you'll know a little something about what theory, design and installation of happens on both sides of the microphones. sound systems, specifically reinforce- this is ment systems, large and small. Al- No, not the April Fool column for real. though it should he required reading -it's The University of Miami is setting up such a ModeI741 S455 for anyone who meddles in p.a. work, program, so run -don't walk -to the nearest Fast ... 700 ips. Versatile ... C. W., there is much information here that wind, reversible. Simple mailbox for more information. The C. C. W. con- will be useful to just about anyone in trols, easy to operate. Hard- Pak /Sof- address is Mr. Bill Porter, Director the audio business. There are some of Center wind, with no pullout crinkle, Recording twenty pages on the decibel notation Services, School of Music, assures perfect product. Heavy duty University of Miami. Coral Gables, systems, within which the various ref- construction throughout . . . virtually Florida 33124. erence systems are explained, as well no maintenance. as the difference between the dBm and the vu. The following three chapters cover Loudspeaker Directivity and Coverage, The Acoustic Environment, and Designing for Acoustic Gain. CORRECTIONS These will he of most interest to the The following errors appeared in p.a. specialist. The Signal Pat /t, by Walter Jung, in 11 Later, the chapter on Installing the our December issue. On p. 34, "2n -1" audico Sound System will prove valuable to should read 2 " -1. On p. 35, Figure anyone who has suffered through 7A, RI is a 10k resistor. On p. 35, Send for free literature ground loops and impedance mis- Figure 7B. the IN914 diode is re- 219 Crossen Avenue matches. Grounding and shielding versed. On p. 37. Figure 8E, +15V Elk Grove, Illinois 60007 techniques are clearly described, and goes to pin 7 of Al, not 1. To order direct call 312 -640 -1030 w Circle 25 on Reader Service Card MARTIN DICKSTEIN Dub faster o o sound im

In a talk given just a few months lights, but out goes the audience. So ago, Mr. Hubert Wilke, President of for presentations. we most always rec- Hubert Wilke Associates, New York ommend rear projection." City, described some of the most mod- The room itself consisted of a nor- em audio -video facilities his company mal front -projection system from a designed recently. The topic Design booth, using both 16mm projector and and Engineering of Tomorow's AV 2 x 2 slides. To use the same set of Facilities fits nicely into the overall equipment for rear projection, the Dub easier subject of the state of the art of audio- audience turns around to face the pro- Garner Model 1056 updates visual -video systems covered at the jection booth, and out of the ceiling your dubbing operation. Five IGC conference in Boston. comes a recessed flexible rear projec- 1200' professional copies in Mr. Wilke mentioned a marriage tion screen, spaced twelve feet from four minutes. Threads fast. Re- that took place in the recent past be- the booth. "With a push from the re- winds in 60 seconds. Single tween communications and electron- mote control. the screen lowers to a

capstan drive and solid state ics. He called it "communitronics." fixed point, framing the alcove . . . electronics guarantee unvary- He said that "we are only in the We have dual image rear projection ing high quality. Priced low honeymoon stages of this marriage and enough for quick payout. Write the birth of offspring in the develop- In RCA's corporate Board Room in for brochure and names of ment and implementation during the Rockefeller Center, New York, there users. years ahead will test the best techno- were several problems. The light from logical minds for generations to come." windows fell on the screen (rear pro- He showed slides of some of the in- jection), the first ceiling light by the stallations his firm designed in which screen had to he turned out to prevent GARNER INDUSTRIES the screens, the lecterns with built -in it from hitting the screen, and the 4200 North 48th St. remote control consoles, the sliding screen was to he hidden until the last Lincoln. NE 68504 walls, the equipment, the lighting in moment before presentation. The pro- Phone 402-464-5911 the room, and the curtains at the win- jectors were also to he left off until Circle 26 on Reader Service Card dows were all considered in the oper- time for showing. The "environment ating plans made before the construc- button" was incorporated into the de- tion had even begun. It's the only way. sign of the remote control panel on For example, in the New York the lectern. One push and the window headquarters building of Time Maga- curtains closed, the overhead light over zine, the client desired a multi -use the screen went off, the panel doors presentation. training, and screening in front of the screen opened auto- room. Mr. Wilke said that "the client matically, and the projectors went on. was interested in utilizing both front The lights over the audience stayed on and rear projection. Normally, when for eye contact and note taking. (The a client says they want front and rear buttons on the panel are lit or off de- o. projection, it is because they really pending on the state of the total sys- don't know which they want and they tem.) Side -by -side slide images, center are trying to hedge their Nets. In this film, and random access slides are all instance, however, Time had a good controlled at the lectern. reason for both. Since the room was Similar designs created for Kodak, to serve not only a variety of presen- Exxon, Xerox, and others all permit @o t t plQgQ tation needs. but would also be used multiple image showings with controls _ SDSTM.TO aDT as a screening room for the viewing of different types engineered for the of t.v. commercials and p.r. films, we user's desires and all tend to make for reel to reel indeed had a multi -use room that creative presentations. The one ingre- serves two separate functions not mu- dient no design can build into any sys- audio recording tally compatible." tem is the presenter. This is a case of AMPEX and Scotch Mr. Wilke continued with the an on- the-job problem. No matter TAPE all professional grades how great flexible the to on reels or on hubs thought that a rear projection arrange- and design ment is usually preferable for presen- keep the show moving, if the pre- EMPTY all sizes, widths tations of any type so "that you can senter sounds (and looks) like he's REELS and hub types maintain good room lighting and yet falling asleep, don't expect the audi- BOXES for all reels, in various colors not wash out the image on the screen. ence to do anything different. The LEADER -,TIMING- &SPLICING TAPES The speaker and audience can main- material being shown may be of great tain eye contact and as anything interest to the speaker, but if he can't Top Quality Competitive Pricing get it all of the crea- Immediate Shipment worthy of note is communicated, the across, any and Call or Write for our Catalog audience will he able to see well tive ingenuity is down the drain. enough to take notes .. . Perish the Then there's the other side of the recording supply corp. closed eyelids during a presentation story, the fellow who loves to click 1291 RAND RD -DES IL PLAINES. 60016 that a heavy lunch with a 312/297 -0955 follows away at slides, and talk, and talk. He martini or two. Not only out go the loses sight of the fact that some time Circle 27 on Reader Service Card must he permitted to allow some of the help. Maybe a lectern mie is the rea- to lose as little (in the translation to material to sink in. Perhaps he com- son for a stiff presentation. The plans) as possible. If you are the con- pares pauses, no matter how slight, speaker has to stay "on" to he heard. tractor, using your head will get you with sin. He's afraid to stop even to Here the lavalier conies in handy. points for the future. There are al- breathe. Systems are designed according to ways a few things that require on -the- Other people who are forced to pre- the desires of the end user, the client. job coordination and maybe some sent because of the nature of their He (or she) discusses the needs, the suggestions. If you sell special equip- business. sometimes feel that any ways the room is to he used, the type ment, see how it will fill a need, technical visual aids will get in their of presentations that will go on in the maybe not even known yet to the way. They become so nervous that room, but there are usually variations client. If you are a prospective client. they forget what they have to say he- betwixt the original lip and the final you, too, can help yourself. Think cause they are thrown by the apparent flip. Not always, but many times, at- ahead. What will you need in the fu- complexity of the controls. They're tempts are made to involve the user ture that you should put in now and deathly afraid of electronic devices of directly. It always helps. If you are save money later? The communitronics any kind. the presenter, you know some of your marriage is moving right along. We're There are many more examples own problems or should get to know all part of it, somehow, believe it or with which you may have come into them. See if you can get the designer not. You too! association during your school days: recording sessions, audio -visual installations, etc. If your business is installing a v, each of these may turn out to he a money maker for you if you can handle it. As an example. out to Front you find a place that has video for playing cassettes of commercials the Our Western heritage company has made so they can he taught demonstrated for their executives. us it's the only place to be. o o Maybe you can put in a system like And today that's where we this. You meet the nian who will he are ... out in front with responsible for showing the cassettes. Qg000 A nice person, but a lot on the nervous audio console CHOICE and

side . . . hands and arms flying. big PERFORMANCE! smoker ... whatever. You sec an op- subject of portunity to introduce the The choice of eleven models leads the industry. a closed circuit, inexpensive, recording set up. Maybe even black- and -white Choose from four to twenty -four mixers. Four to 1" "i l 1 1 to start with. Here's a chance for this seventy -two inputs. Choose mono, stereo, 44QQ0 man to see for himself what he looks quad -capable ... for radio, TV, recording and like when he presents. He might even get points with his superior if the special applications. upper boss has the fall- asleep approach to speaking. The situations may not he And performance? State -of- the -art O:fi Iwo real. but the need for a simple system performance above industry standards. just to have the presenters train them- ®©OQOQQ Q selves is worth the cost many times Performance so outstanding that we over when the improvement is no- GUARANTEE YOUR SATISFACTION. ticed. The number of executives who may have hacked into viewing them- Put your IN selves on little systems bought to train station OUT FRONT lower echelon personnel is legion. with a Sparta console. Many industrial firms have set up video studios for the purpose of hav- Call us now. ing top men get a look at themselves with a speech they have to make to the hoard, or to the West Coast office. or to the big man, or ... It may seem simple and old -hat to you, hut then you're in the business. They're not! The remote control lectern also has the ability to tie a speaker down to a single position during his whole talk because he has to push buttons to keep the show going. He has to look at his script, then at the controls and sometimes at the audience, too, if he is to keep eye- contact. Here's another way you can he of help. You help yourself, too, if you can cone up with job -site recommendations to keep the speaker from freezing. Sometimes, a XPARTA remote control box with some of the e remote controls of the lectern are a 5851 f Yxn PerYw RINK,. Sacrament(' C., `n4l]t1 11e .IÖJ '..I'+.1 telex :1))488 Cade SPARTA LP Circle 28 on Reader Service Card 1139 new producls&services

STEREO MOVING -COIL LIGHTWEIGHT PORTABLE BI -POLAR POWER SUPPLY CARTRIDGE CONSOLE

Adjustable d.c. voltages from i- 14 to ± 16 V at 4 amps are provided by Trouper III console contains mod- model 7000 power supply. The unit ules weighing 20 pounds apiece and operates off 115 VAC, 60 Hz input measuring 151 _ x 19 in. Three mod- EMT XSD -I5 hand -made stereo power and includes crowbar over- ules create a 28 -input hoard. Each moving -coil cartridge is built into its voltage protection (limiting the output input contains a level control. solo own shell which fits tonearms using to 18 volts), foldback type current switch. 3 -band equalizer, monitor and the international plug -in configuration. limiting, and inter -locked output pro- echo send. led peak indicator, mic A magnifying lens in the shell sim- tection. Other features include remote pads, and group assign switches. Out- plifies cueing. Each cartridge comes sensing, resettable power line circuit puts include subgroup level controls. with its own B &K chart showing its breaker, an overload indicator, and with solo switch and equalizers; house. frequency response curve from 20 Hz front panel voltage adjusting controls. echo receive, and monitor control. to 20 kHz. FIM distortion, output Mir: Modular Audio Products The console also contains a preview voltage, and channel separation. Circle 53 on Reader Service Card system with switchable meter and Mfr: Gotham Audio (Distributor) peak indicator, headphone jack, head- Price: $300.00. phone level control, and preview se- Circle 50 on Reader Service Card lector switch; announce level controls, as well as two auxiliary receive controls for line inputs. Mfr: Uni -Smnc, Inc. / TI4F r'r1MPI FTF IiFFFRFN(`F The Circle 51 on Reader Service Card Sound System R.A.Neilson PASSIVE EQUALIZER Engineering JUST PUBLISHED -EVERYTHING YOU NEED TO KNOW TO TAILOR Company. SOUND SYSTEMS TO SPECIFIC REQUIREMENTS. MARKETING SERVICES FOR Includes: Audio Systems THE PROFESSIONAL AUDIO Decibel Notation AND System VIDEO INDUSTRY. Loudspeaker Consultation Advertising Directivity and Coverage Sales Promotion Research The Acoustic Industrial Design Technical Environment Designing for Acoustic Writing Personnel Search. Gain As a passive device, no noise is Interfacing Electrical introduced by model 4004 one -third and Acoustical A technically oriented Systems ocativc audio equalizer. All filter sec- Installation, Full- Service Agency. tions are designed for low distortion; Equalization, the manufacturer claims an absence of Instrumentation, hard clipping at high level. Each filter Specifications 3378 Oak Glen Drive 295 pages is a double -tuned constant -K section Los Angeles, Ca. 90068 with two precision lc pairs. The adjust- db The Sound Engineering Magazine SAGS:Aoki, Pek1LMNIS.; (V). (213) 851-6855 ment range is zero through -15 dB by 1120 old Country Road calibrated front panel controls. High - Plainview, New York 11803 Please send me copies of cut and low -cut adjustable filters are SOUND SYSTEM ENGINEERING (21156). I have enclosed $19.95 + .50 used for spectrum finishing. A socket postage and handling. Add sales tax is provided for plugging in a crossover where applicable. network to give a hi -amp output. Name Mfr: White Instruments, Inc. Street Price: $760. City State Zip / TCO Circle 52 on Reader Service Card Circle 29 on Reader Service Card ACOUSTIC CONTACT PICKUP VARIABLE PITCH CONTROL CALENDAR

MARCH 2 -5 Audio Engineering Society, 53rd Convention. Hotel Inter- national, Zurich, Switzerland. 7 -12 Audio -Visual Institute for Ef- fective Communications. Indi- ana University, Bloomington, Increased flexibility in recording Indiana. Contact: Audio -Visu- speed is made possible with A700 va- al Institute, 3150 Spring St., Lightweight acoustic pickup Iner- riable pitch control. The device fa- Fairfax, Virginia 22030. (703) tial Accelerometer D642 easily at- cilitates the continuous sweep variation 273 -7200. taches to any instrument, including of tape speed over ±7 musical half 21 -24 National Association of Broad- guitars, basses, violins, banjos, drums, tones. Therefore, together with the casters Convention. Chicago, and pianos. The device is claimed to three standard speeds. the complete Illinois. Contact: NAB, 1771 reproduce true tone quality without range of 2.5 to 5.6 in /sec.: 5 to 11.2 N St., N.W., Washington, D.C. distortion even when an amp is used in /sec.: and 10 to 22.5 in /sec can 20036. (202) 293 -3500. at full power. is built in. Fre- Gain he achieved. A built in sync light quency response is 5, more than 15.000 indicates "On Speed" at all whole, and Hz. The pickup comes with four extra fraction of a whole, speed selections. APRIL adhesive seals, foam protective pads, Mir: Revox Corp. 5 -9 Acoustical Society of Amer- extension cord and a dome that lets Price: $85.00. ica. Washington, D.C. with musician vary the response curve. Circle 56 on Reader Service Card Mir: Duna Magnetic Devices 22 Acoustical Conference. Hun- Price: $39.95. garian Society for Optics, Circle 54 on Reader Service Card SOUND FILM SYNCHRONIZATION Acoustics, and Cenematog- raphy. Budapest. Hungary. T; Fa 26 -27 Acoustical Problems of Light - - se - Structure Construction of Build- < tj id'VIII ings. Acoustical Commission SEARCH AND CUE COMPUTER of the Hungarian Academy of Sciences. Budapest. Hungary.

MAY

::*411116> I Midwest Acoustics Conference. One -day meeting covering sig- The Digital Interlock synchroniza- nal processing and data reduction system incorporates sound along tion technology for solvingtech- with a silent film through the use of nical and legal problems in Tape can he automatically re- a step drive motor driven from a acoustics. Norris Center, North- turned to one 16 any of locations power unit within an electronic con- western University. Evanston. stored in - the memory of model 400 sole which generates pulses or signals. Ill. Contact: H. O. Saunders, RSM computer. Using an all digital The step drive motor is fitted within Rm. 24A. 225 W. Randolph technique, the computer continually the casing of any standard 16mm or St., Chicago. III. 60606. (312) calculates the velocity optimum tape 35mm projector to undertake the func- 727 -4331. and prevents the recorder from over- tion of the existing drive motor. (The 4 -7 AES Show. 1.os Angeles, Cal. shooting its destination. All input data projector can also be used conven- 28-31 Sound and Vision '76. Bir- is single obtained from a optical pick- tionally when so modified.) The sys- mingham. England. up mounted under the tape deck. Out- tem can also be used with sprocketed put signals to are fed the tape trans- sound tapes, using two standard film Copies of all issues of db -The port remote input socket. Applications projectors, one for sound and the include -track and Sound Engineering Magazine start- multi overdubbing other for film projection. If the syn- mixdowns, live recording, duplicating, ing with the November 1967 issue chronization signal is derived from as well as on-the-air radio program- are now available on 35 mm. micro- one track of a tape recorder, the film film. For further information ming. or to projector will he held in exact syn- place your order please write di- Mir: Oliver Audio Engineering chronization with the moving tape. rectly to. Microfilm, Inc. Price: a $1.495. Using a multi -track tape, several lan- 300 North Zeeb Road v Circle 55 on Reader Service Card guages can be applied. Where two or Ann Arbor, Michigan 48106 more projectors are synchronized, the film speed can be varied up to 50 frames per second in forward or re- GIVE... verse. Lip synchronization can be obtained, using a cassette tape recorder, HEART without putting a magnetic stripe on a savenergy m silent film. FUND Mir: Elf Audio- Visual, Ltd. Circle 57 on Reader Seruice Card -4 products & services (cont.) two -channel switchable record or playback system combines 30 dB of broad- band noise reduction with a 10 dB SWITCHING AMPLIFIER increase in tape recorder headroom. It requires no level matching. Mfr: dbx Price: $600.00 Circle 60 on Reader Service Card

MIC SNAKES

"Class D" amplification, using transistors which turn on and off a half -million times every second, is produced by the DSP (Digital Signal Processing) switching amplifier. The ING unit delivers 250 rms watts per chan- TECHNpLO OP nel under any line conditions. a.c. or June 21-july 9,1976 d.c., from 96 to 240 volts, with no thermal degradation. The elimination These portable multiconductor ca- WRITE: of large heat sinks has made it pos- bling mie snakes feature tinned cop- Brigham Young University sible to reduce the size of the ampli- Special per conductors and color -coded poly- Courses &Conferences fier to 183/4 x 4" x 12 inches; it 242 HRCB propylene insulation. They are cabled Provo, Utah 84602 weighs 35 lbs. in pairs, with Switchcraft A3M and Mfr: Infinity Systems, Inc. D3F connectors. Concentric wire mesh Price: $1.850. strain relief with rubber clamp down Circle 58 ow Reader Service Card collar eliminates crimping or twisting. Shield (drain wire) integrity is main- COMPRESSION DRIVER tained throughout as well as foil shield continuation to within one inch of the terminating conductor. Mfr: Audio Transport Systems Circle 61 on Reader Service Card Circle 31 on Reader Service Card AUTOMATED BROADCAST SYSTEM

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A COMPLETE CONSULATION ADD -ON NOISE REDUCTION SERVICE FOR STUDIO PLANNING AND Completely computer -controlled CONSTRUCTION broadcast system 3000 uses the computer as a decision making device as d6: FREE -LANCE RECORDING .aa well as for memory. The system can SERVICE IN THE be used for programming, instant re- formatting. as well as other applica- NEW YORK AREA tions, such as billing. It automatically The shift in tape hiss and degrada- provides print -outs of verified logging. 212 673 -9110 tion in program quality which may has an automatic re -start in case of 64 University Place accompany the change from studio power failure and a memory storage recordings to those made in the New York, N.Y. 10003 field capability of up to seven days of is diminished by the use of model 192 operation. It has 16 source channels, bolt -on noise reduction system de- featuring solid state operation. signed to be used with the Nagra IV -S Mfr: Spectra Automation portable stereo tape recorder. The Circle 62 on Reader Service Card CUSTOM CONSOLES THREE -WAY LOUDSPEAKER Erase faster r Erase cleaner

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are making beautiful music together. When Richard Alderson of Rosebud Recording Studios, New York saw and heard our Model 3000 Variable Parameter Equalizer he was impressed! So impressed that he asked what other console modules we had for the board he was building. So we showed him. The final result, proudly shown here is Rosebud's new 20 input 16 track console. They built it themselves using MAP's Model 8422 series plug -in modules and Models 3000 and 3100 Equalizers. So if you're thinking about a new console, do what Richard Alderson did ... take a look at Modular's complete line of nine great console modules. (listed below.) Whether you choose one module or all of them, you'll be impressed too. Call or write Rick Belmont or Martin Gittleman for technical assistance on putting together your next console. MODEL 8422 -1 8422 Module less mixing amplifier MODEL E8422 Echo /Delay- Send /Receive Module MODEL C8422 Control Room Monitor Module MODEL S8422 Studio Monitor Module MODEL T8422 Communications and Cue Module MODEL MB8422 Input Module Mother Board MODEL 3000 Variable Parameter Equalizer MODEL 3100 Graphic /Shelf Equalizer MODEL CL-20 MODULARCompressor- Limiter AUDIO PRODUCTS, Inc. A UNIT OF MODULAR DEVICES, INC. I`.1tRP 1385 Lakeland Ave., Airport International Plaza- Bohemia, New Yo-k 11716 516-567-9620 CD Circle 33 on Reader Service Card Bunker Hill Pavilion at Charleston, Mass.

MARTIN DICKSTEIN

The Whites Of Their Eyes

The Battle of Bunker Hill, brought to life in an ingenious multi -media presentation, is an educational experience for the kids and a technical feast for engineers.

WELCOME to the Bicentennial Year, 1976 -the 200th anniversary of the United States. On July 4th. the country will celebrate the official date of its birth, but a great deal took place before the historical day arrived to make the event hap- All photographs have been supplied through the courtesy pen at all. Most of the events leading up to the Declara- of the Raytheon Co.. White Oak Design Co. and tion of Independence took place in New York, New Jer- A. V. Services. sey, and Pennsylvania, but it all began in Massachusetts, A manikin of British lieutenant Colin Townsend is one Jay O'Stine of White Oak Design puts finishing touches of 22 life -size figures. on a model of the "all around" auditorium where the presentation is housed.

in the vicinity of Boston. It is in this same location, not move by the British, they moved toward a small spit of far from the monument set up to commemorate the high land jutting out into Boston harbor. The town of Battle of Bunker Hill, that the first major audio/visual Charlestown was on this small place of land. as was display has been set, up on a permanent basis, to depict Bunker Hill. Leaving men along the way, including 900 one of the most important incidents in the story of the soldiers up the hilly ground, the colonists dug in where struggling colonies to free themselves from foreign rule. they stood -on Breed's Hill, not Bunker Hill which they There are others, just completed or nearly so, in other had just passed -and started to build a fortress. This was major cities where it all took place, but it is this one in on the night of June 16, 1775. The British on hoard the Boston they will have to heat for historic accuracy, tech- ships did not know of the work. Although the troops in nical ingenuity, and sheer dramatic impact. the city of Boston heard the sound of building. they de- cided to wait until morning before doing anything. In the morning, the British on the warships saw the wall HISTORICAL BACKGROUND and began a cannonade. One of the colonists went for In order to understand the audio /visual undertaking it- water during a lull in the bombardment. A shell caught self, some of the background of the depicted event is a him before he could go far. He was buried on the spot. must. The Boston Massacre in 1770, the Boston Tea the first American casualty of the battle. Along the beach. Party in 1773 and the closing of the Port of Boston led up a small fortification protected by a low stone wall was to the desire of the colonists to resist any such further hastily erected. activity by the British. In August, 1774, the stores of The British soldiers started their move uphill, with crack guns and ammunition accumulated by the local farmers troops moving along the beach. It was early afternoon - were raided by the Redcoats, and the first battle of re- the temperature was about 90 degrees. In the town, people sistance almost took place at that time, but the gathering took high places to watch the battle. The British moved of 10,000 farmers at Cambridge Common disbanded with- along the beach. When they reached a stake stuck in the out incident. It was learned that the British had plans to ground about forty feet in front of the wall. the crack go after the stores of arms in Lexington and Concord. The shot marksmen of the colonists, hiding behind the wall. British had two choices of where to strike first -either opened fire. march first and then cross the water, or go by boat first The trick here was that the colonists had formed three and then march. The two lanterns in the Old North Church line;, one above the other, to he able to fire steady vol- tower told of the decision to move by water first, but Paul leys: first, the kneeling soldiers in front, then the next Revere had already rowed across the river right under the row crouching, then the third row standing. The British cover of the British ships so he did not even need the now ran. They tried twice, charging up the main hill, but famous signal. He alerted the local people, and when the with full uniform and 100 pounds of pack on their backs. British, after failing to find the stores, started to retreat, they didn't make it. On the third try, with coats and the colonists took a position and each side fired on the packs on the ground, they finally got the colonists to run. other. The "shot heard 'round the world" started the war. The decision behind the fortress wall to make every shot This was April, 1775. count and not to fire "until you see the whites of their The British were determined to make up for their ig- eyes," cost the British over 200 of their top fighting men. nominious routing by the colonists. The gathered forces and over 800 wounded. The colonists lost over a hundred of the colonists added up to 15.000. Aiming to prevent a men, with more than 300 wounded. The Americans lost up to 150 standing people. At a height of about 15 feet off the floor, the projection booth is suspended independently of the building roof to eliminate the effect of roof deflection on the precise registration of the show projectors when the roof is loaded with snow. The booth protrudes from the rear wall over the audience arca. The architects were Anderson. Beckwith. Haible & Reeve and the general contractors were A. J. Martini Co.

THE SHOW Once the show was conceived. John Jacobsen, Steve Rich. Tim Curnen and O'lay Stine, all of White Oak De- sign, set about getting the script written, the special ef- fcts worked out, the lighting and sound figured out, and the details of the production in working form. The consulting firm of Hubert Wilke, Inc. of New York, was asked to design the audio -visual aspects of the show. They worked very closely with the show creators to set up plans and specifications that would portray the material of the program to the best advantage. Audio Visual Services, Inc., New York, engineered and supplied the sound and projection, as well as the control systems of the program. Recording and mixing was done at Intermedia Sound, Boston. John Jacobsen of White Oak Design checks up The presentation was designed to include the audience on the 7- channel Ampex 440 -8. used for digital audio in the action. were to almost the way cues. Sets arranged go all around the standing visitors -a part of the show even takes place behind the people. With the enclosed projection booth overhead, there is no distraction caused by changing lights and the operation of projectors. The main portion of the viewing area consists of a total of fourteen the battle, but they had proved to themselves -and the screens, of different sizes and shapes, in irregular groups, British -that they could flight. The British won, but what? one cluster having perhaps threce screens, another with Only a small hill. for which they paid heavily in casualties. two, another with only one. There is a total of six group- So, a diversionary tactic became a full fledged battle ings in all, at differing levels and positions. The space be- fought on a spot for which it was not named nor where tween the screens is filled with paintings and settings of it was originally intended to be fought. This, then, is the pertinent people and places, and a total of 22 life -size fig- story of Breed's (not Bunker) Hill. ures in groups and positions relating to the story. The detail of the figures, the clothes, the guns, the incidents depicted are historically accurate and made with great pre- THE BUILDING cision. Much of the history -rich Boston area could have served When the audience enters from the rear, the room is as the focal point of the audio -visual display conceived by dark except for a diffused light from above, illuminating White Oak Design, Inc., of Boston, but the decision was the audience floor area. On a single large screen there is a to portray this most important battle. The idea was pre- projection of a proclamation of martial law in Boston. A sented to the Raytheon Corp. of Lexington, and they general background sound is heard of horses, children, agreed to fund the undertaking. A non -profit foundation people -the audience has the sensation of being in the image on the was set up and the Bunker Hill Pavilion was built at a midst of the town. The lights fade, the cost of $1,500.000. Research of old documents turned screen disappears, the .sounds stop. and a voice begins with up reports by people who saw the battle, letters by partici- the background. leading up to the events to be seen. The a side who is pants, and a tremendous amount of detail regarding cloth- story is continued by seated figure on one side ing worn, the plans, the armaments used, and the people reading a letter he just wrote. As he tells his of the involved. This material was gathered under the super- story, as a Briti =h soldier, the faces of the generals men- vision of former M.I.T. Professor Douglas P. Adams of tioned come up on screens. Cambridge and Thomas L. Davis. Every detail necessary The narration moves to a Yankee soldier on the other to create the most authentic program possible was used. In side of the diorama and again, images help tell the story fact, almost every spoken word in the show comes from As the events unfold, the show is all around the audience, documented evidence. both visually and aurally, on screens and figures. and be- The construction of the 10,000 square foot building hind as well, recreating the burning of the city of Charles- took exactly one year from beginning to end. The brick town by the British before the battle. The effect of move- structure has some special features which take into ac- ment is created by varying dissolves on screens and timing count modern day problems, not even thought about in of projection. Authenticity of detail is enhanced by the colonial times. Reinforced concrete with insulation is used dramatic images and life -size figures illuminated as dimly to soundproof the interior against the sound of the ex- or intensely as required. Strobe lights and effects of gun- pressway which runs just outside the walls and the roar of fire and flames are cleverly intermixed to simulate realism aircraft coming and going at Logan International Airport, effectively. A specially written ballad is sung and played just across the river. (Today, in a similar maneuver, the through the program to help keep the fast pace and the British Men of War would have to pass the airport to get narration moving. Although the show is less than twenty to their positions for the battle.) minutes long, it seems to cover a tremendous amount of N N The audience area is about 40 feet square and can hold history quickly and excitingly. THE TECHNICAL ASPECTS used for sound. voice, music, and effects throughout the The ingenuity of the audio -visual system design and its program. execution arc what make the program as effective as it is. The audio is fed from the tape deck preamps to The projectors are Kodak Carousels mounted on six Op- Soundcraftsman equalizers through Crown D150 dual am- tical Radiation Xenographic 5I2C units. Each unit con- plifiers to Altec 604E speakers in utility housings. The sisting of a xenon light source with two slide projectors equalizers are dual 10- frequency units. Since speakers are the mounted on the front of the housing, covers a single screen mounted around the periphery of the audience, within configuration. The light output of each unit is 5,500 lu- sets at the screen locations and, over the heads of the mens at a nominal color temperature of 5,400° K. A people. on the ceiling under the protruding projection mechanical dissolve system is incorporated within the light room, the room had to he tuned very carefully to elimi- source housing, since the xenon lamp cannot be turned on nate ringing and standing waves. Each equalizer /amplifier and off as needed. With the sanie light used on both pro- combination was set up together for each of the speakers jectors, the light housing of the projectors is modified to (each amp feeds its own speaker, hard -wired, with no permit straight- through illumination of the outside source. switching) according to location. There are a total of ten An advantage of using one light source for the two pro- speakers, six around the show area, and four above. Each the six jectors in the system is that the illumination remains con- of units is fed by a single amp, the cluster by two stant when the dissolve is activated, instead of having the amplifiers. (Dolby noise reduction is used between tape variation that can occur with each projector having its preamps and equalizers.) No attempt is made to locate the speakers screens own lamp. The horizontally- mounted xenon bulbs have a near or the life -size figures. Separation of rated life of 2,000 hours. The projection room is specially speakers is sufficient to bring the attention of the audience cooled and ventilated to assure proper operation of the to the active area and realism is maintained without any equipment. attempts at specific "speaking" figures or screens. Inasmuch as the screens have different shapes and are clustered in unique configurations, the slides also had to CONTROL SYSTEM he made specially for the presentation. A total of over The control signals for activating lights and projectors 500 slides is used in the 12 drums. Since dissolve action cone from track 5 of the I inch tape. These trigger the must be accurate, the registration of slides in paired pro- FS -255 Audio Digital System, developed by A. V. Ser- jectors must he precise. Slides could not be used in the vices. Inc., N.Y., the a/v system installer. Of the total standard horizontal format. so special masks were made for capability 255 channels, 37 are utilized. each slide. The mask shape depends on the screen configu- of only of them Each projection unit requires six signals (cut. dissolve tim- ration to he covered. In the single screen, the slide takes ings of 2, 4. 6, or 8 seconds, and shutter block the the shape of the screen. Where two screens are used, the -to on the to be or vice One masking permits openings to correspond. In three-screen light projector darkened versa). application. the mask again matches. Yet another innovation was required in making the slides. With the angles of projection varying and steep (91/4 degree, oft' the horizontal in one case), the keyston- ing at the throw distance used would he unacceptable. The masking was also shaped to eliminate the keystone effect Judge by the sound, and to ensure that the image fills the screen accurately. The effect of having the screens slightly tilted downward toward the audience was also taken into account. The not by the pound. dissolve rates of the Xenographic are from one to six In the past, you could often judge the quality of a seconds, with quick cuts also possible. The control system speaker system by its size and weight. But we've for the dissolve units extends this capability to permit fades changed all that. With the BOSE 800 Professional in 2, 4, 6, or 8 second intervals. With the single light Loudspeaker System. source, and accuracy of slide registration, the varying rates of dissolves during the show are very effective. The 800 gives you the kind of sound you couldn't The artwork created for the slides to depict scenes or get before... natural. Crisp and clear, with no troop movement toward or away from the audience is mud, honk or boom. exceptional: the facial expressions up close are amazingly And it's incredibly portable. So you can attend to real. In order to he able to replace slides as needed, the your business of making sound, not muscles. original masters are not used, even in duplication. A Get the quality pro- separate set of masters has been set up for duplication fessional speaker purposes. The originals will he used only when the proc- .,< essing masters need replacement. system that won't weigh you down: the BOSE 800. SOUND EQUIPMENT The sounds of the background city originate on a 1/4-in. cartridge tape played on an International Tapetronics deck. This permits continuing the preliminary sounds as long as _41917SF15/00 - needed for the audience to enter the theater. The tape begins automatically when the show is over, and stops play- Please send information on BOSE Pro Products to: ing when the attendant outside the room, in the audience entrance area, has allowed the next group of people in. Name The sounds are fed to all speakers to avoid any real di- Address /State rection to the effect. With the activation of the show from City /Zip Telephone t the control panel, the I -in. show begins. An Ampex tape Return to: Dept. SE, BOSE, The Mountain, Framingham, MA 01701 440 -8 is used for this tape. All channels but number 5 are a paper tape again, the audio signals can he fed hack to punch another paper tape. Making duplicate punched tapes is also po;,ihl.2 with the automatic punch. (The speed of the total control system is 100 closures per second.) In order to he sure of the precision of all cues. sounds, balance, and synchronization, the producers made up long running sheets for the entire program. Sound signals were indicated by channel and time. A master sheet showed cues, sound., lights, and effects by times so that every signal was exactly matched to every other. Long hours were spent to make the show work as it would have to in order to he effective. The result is obvious in its accuracy to the smallest detail and technical ingenuity.

AUTOMATION Precautions were also built in should any operating problem come up. The show is automatic once it is started. That is, the program tape starts, the background cartridge stops, and the action continues until conclusion. At the end, a quarter-inch of oxide is scraped from the Audio digital control and Synch System automatically audio tape. This is sensed by a light -sensitive device, which monitor every step of the program. automatically starts the background tape and switches it into all channels, turns on the lights, signals the slide trays to move until a microswitch on each projector is activated by a raised piece mounted On the side of the drum in the zero position, opens the shutter on projector 4 to show the first slide seen when the audience enters, and starts the audio /control tape to rewind. At the beginning of the tape, another blank space is channel is used for lighting cues to activate a completely Nei-aped to stop the tape. This is also a unique setup separate system provided by Capron Lighting of Boston. -the speed of the tape would cause damage if the brakes were The control system consists of an Audio Digital Con- suddenly applied. Instead, the speed is slowed down troller, programmer, automatic punch, and accessory edit gradually as the supply reel becomes close to full. When controller. The control console for originating the signals the brakes are finally applied, the tape is travelling rather resembles a button system on a pushbutton telephone. By slowly. Since the tape now has to get over the scraped pressing the desired combinations, an eight -level binary code stop position during the starting procedure, a delay relay is sent to the punch, which puts the signal on a paper tapa. is used to cut out the light- sensitive device until after the The console also has readouts to indicate the tape posi- open spot has passed and the oxide is in progress. tion, by step number, and the cue channel. When the An automatic emergency system is also installed. If tape is played back, the signals of the punched holes are someone is working on the system during the holding fed through the controller, first for test only if desired, period, a switch is thrown on the control panel in the then to put the audio signals on the control track. (The control room which illuminates a warning amber light on controller can he operated directly by the programmer if the control room panel and on the one near the audience desired.) Once it is determined that the show is all set, area. This indicates to the starter that a hold is in progress. the paper tape can he discarded. (The edit controller is When the work is completed, the switch is returned to used for timing changes by use of a keyboard.) If it is normal, and the show light (green) goes on again. In the desired to change the cues on the tape, or to re- establish event of trouble, the system can he stopped, a red light goes on, all lights go on, and the show is automatically reset to the beginning, A similar situation can occur if the emergency announcement microphone (one in the office and one in the control room) are activated. An operator in the control room has a monitor system which. permits him to hear all audio channels during a show, and the background material during hold period, The system can he checked quickly this way and troubles corrected quickly. The building (which opened on the 200th anniversary of the Battle of Bunker Hill) has been leased for 20 years. This means the show will go on, and on. It is the largest of any audio-.visual programs for the Bicentennial in the Northeast and certainly deserves serious consideration during a trip in that area, It is located just 200 yards from the ship Cons/hot/on, another sight to see in the same area..) A nominal fee is charged at the Whites Oj Their Eyes presentation to cover operating costs; the operating foundation is non -profit. it is the first to open in the celebration year. and will definitely he the most out -. standing for some time to come, No trip to visit the places where the Bicentennial began can be made without first Punch -tape control units provide audio cues for seeing where the history of the independence of this recording on the one -inch show tape. country started, DANIEL QUEEN

Psychoacoustics

There's a beautiful symmetry between hearing and all our other senses.

OST READERS of this magazine will be familiar as the Hass, or prece- R with such concepts nn o dence a /Jeer in the application of time delay to sound systems or in methods to fool the ñ IOR semis into thinking that something is originating as a "vir- tual source. Yet, how many of us have thought about the similarity, of these psychoacoustic phenomena -that is. a phenomena associated with our hearing sense -to peculi- arities of our other senses? Figure 1. The electrical analog of a sensory receptor I have always been curious about the ubiquitous factor membrane. of sixteen that we find in the minimum frequency discernible as a tone, the minimum flickerless frame rate for motion pictures, and (as a reciprocal) the maximum fusion time for echoes. Similarly, there seems to he a short time -about a millisecond -coincident in the maximum separation of impulses from separated sources before localiza- to tho.m, identical o tion moves the first of and the almost CMP visual phenomenon of distraction due to flashes and of o backward masking. Even more curious is the fact that the lowest discernible sound frequency perceived by our cars as tone-not pulses-is the sanie as the lowest discernible vibration frequency perceived by our sense of touch. Figure 2. The electrical analog of a sensory- neural Many of us had been exposed to the concept of critical junction. flicker frequency as applied to film and had always sus- pected that this phenomenon somehow related to the other senses. Yet, as if as a testimonial to continuing education, the answer turned up in a recently introduced undergradu- In general, the data says that our hearing sense will place ate general biology text. All fond hopes that the phenom- the location of a sound which originates from two sources enon was due to some sophisticated programming of our (such as two separated loudspeakers) somewhere between higher brain centers disappeared as the text pointed out the sources. The exact location depends on the relative that the phenomenon is common to all vertebrates down intensities of the sounds from each source and their rela- to the lowliest fish -as Well as to all our senses. tive times of arrival. However, when the sounds from the Let us review the transient behavior of human hearing. sources are separated in time by more than approximately The precedence effect has been described by many observ- one millisecond, localization will always be at the first ers, usually in terms of localization and echo perception. source.

ECHO FUSION Daniel Queen is head of Daniel Queen Associates, The second phenomenon is that of echo fusion, This ef- N consultants. of Chicago, Illinois. fect causes an echo arriving at the listener Within about 63 ut TIME THRESHOLD POTENTIAL -1 INPUT RIGHT EAR 1 111111111 1

LEFT OUTPUT I E 1 i IJL1111JIllllll1l1lJll111J 1 i i EAR 1 11111111111

Figure 3. A time record of sensory excitation. Stimulus Figure 5. A nerve pulse trains for a real or simulated causes a rise of receptor "generator potential" right -side sound stimulus. until it exceeds threshold potential, whereupon it creates pulses of "action potential" in a nerve.

TECTORIAL MEMBRANE ality, the stimulus is carried along the nerve fibres to the brain as a pulse train. The intensity of the stimulus is ac- utally a function of the number of pulses in that train - BASILAR MEMBRANE disgustingly similar to the operation of an analogue -to- digital converter. The input pulse to the circuit is the result of sonic change in a sensor. In the case of hearing, it is a change in stress upon the hairs of the hair cells lo- Figure 4. A schematic representation of the hearing cated along the basilar membrane in the cochlea. receptor mechanism. Relative motion between the FIGURE 4 shows a diagram of the human hearing sensor. basilar membrane (which is excited) and the tectorial At the point where the sound coupled from the ear drum membrane produces stress on the hair cells (the into the cochlea enters. the basilar membrane is thick. It sensor- neural transducers). becomes thinner and lighter as one moves further out upon it. For this reason. th. thick part will resonate sym- pathetically with low frequencies and the thin part with high frequencies. Thus. hair cells located along the basilar membrane will he stressed only by the frequency to which the adjacent portion of the membrane is sensitive. From milliseconds of the direct sound (or the first sound heard) each hair cell, a nerve fiber enters the auditory nerve bun- to fuse with the first sound. reinforcing it in loudness, but dle and is connected into the hearing center in the brain. not changing its information content in terms of locali- Thus, each nerve fiber transmits pulses only associated zation. Sounds arriving after about 63 milliseconds are with a particular band of frequencies. usually heard as discrete echoes. The exact fusion time It is easy to see from this that if the capacitor is charged seems to vary somewhat with the frequency content of the by pulses at a certain frequency and other pulses enter original sound, and the physiological condition of the before the capacitor discharges below the trigger point of listener. the negative resistance device. rather than there being a If someone wanted to build an electrical analogue of sensation of a separate stimulus. there will be. instead, a this sensory pattern. he could use the simple circuit shown sensation of greater intensity. Since a reflection can con- in FIGURE 1. The capacitor shown can charge rapidly up sist of only those frequencies that were in the direct sound. to the limit determined by the zener diode but must dis- it is obvious that the direct sound arriving first will provide charge slowly. Any pulse coming in during the charge the intiation of the stimulus; reflections arriving before the time will contribute to the charging. but any pulse coming capacitor discharge will only intensify the stimulus. in after the zener voltage is reached will only extend the How then does localization occur? In FIGURE 5, we have time before discharging. plotted the potentials associated with the two ears. Each. of Now, if we take out the zenor diode and put in, in- course. has its own nerve fibers and its own entry into the stead. a negative resistance device followed by a compara- hearing centers in the brain. Pulses must come in to tor. we have the circuit of FIGURE 2. What happens now charge the capacitor up to initiate output pulses from the is shown in FIGURE 3. As the charging pulses come in. comparator. Since the pulse arrives first at one ear nothing comes out of the comparator until enough charg- and then the other. when the pulses are of equal intensity, ing pulses of sufficient intensity have come in to bring the output pulses will he initiated from the car closest to the voltage on the capacitor up to the breakover point of sound source first. The brain will receive signals indicating the negative resistance device. At this point, a sufficient the difference in distance from the sound source. voltage will be produced to cause the device to tire, out- Now what happens if we initiate the same stimulus from putting an impulse. If pulses continue to come in, the out- the two separated sources? As shown in FIGURE 5. the put device will continue to produce these impulses. As long pulses will now arrive in a manner which modifies the as the input pulses continue to maintain the potential time of initiation of output pulses. The amount of modi- across the capacitor. output pulses will he produced by the fication will depend on the relative intensity of the sources comparator. However, once the input pulses stop, the and their relative time of arrival. However, the sources, in capacitor will discharge, stopping output pulses until a new order to interact in this way, must both provide pulses to set of input pulses causes the capacitor to charge again. the ear during the "charge" time.

CRITICAL BANDS THE HUMAN COMPUTER It is interesting to note that this phenomenon also can m N According to this representation, which is close to actu- explain the manner in which masking takes place in so- called critical bands. If the capacitor associated with a par- and the discharge resistor are actually the sank membrane, ticular frequency hand is already charged, another stimu- hut, because this type of membrane is differential, ions lus at the sanie frequency will only contribute to an ad- flow through it in one direction more readily than in the dition of intensity, whereas a stimulus of a different fre- other direction. Thus, the rapid charge and slow discharge quency will excite a different capacitor and give the sen- associated with the phenomenon is explained. sation of additional stimulus, causing the new stimulus to It is also readily seen how such a membrane can act as he audible. the negative resistance device we have described. One A similar situation exists in vision, except that instead membrane exists, in effect, at the input to the receptor of hair cells, the receptors are the rods and cones in the cell. allowing the input stimulus to charge the cell and retina in the eye -each of which also is connected to a another membrane exists at the interface of the receptor single nerve fiber pressing in the optic nerve bundle to the cell and the nerve cell. causing the production of nerve visual center in the brain. Similarly, the receptors of the pulses. These receptor cells and their associated membranes sense of touch are connected by their own individual are remarkably similar for all the senses and explain the nerve libers hack to the brain. It should he noted that the also remarkable similarity in the characteristic stimulus brain has an "addressable buffer" called the thalamus. times. to which enables the brain to sort and select in its effort It is also clear that anything that will affect the electro- concentrate. lytic balance of the body fluids will affect these characteristic times. Many well -known substances are known to affect the OUR INTERNAL ELECTRICITY chemical balance (or homeostasis) of the body -among them, alcohol and drugs. The chemical balance Now that we have described the circuit in FIGURE 2, is also known to he affected by the time of day. the can we actually show that it exists in the human body amount of sleep that one has had, and by diet. It is easy and particularly around its sensory receptors? The fact is to see why observed times can vary over a fairly wide that the body actually does have a complex set of solid range among individuals. It is also clear that, without care- state rectification negative resistance devices. They and ful physiological controls, many of our psychoacoustic ex- are electrochemical in nature and their carriers arc ions periments will be subject to great error and contradictory and than electrons. The (sodium potassium) rather junc- results. tions of these devices are permeable membranes which separate fluid- hearing tissues. The sensory receptors func- A little imagination would suggest also that artificial tion by stressing these membranes in a manner which acoustical effects, particularly involving a stereo or quad changes their permeability, therefore allowing positive reproduction, might be sensed differently by persons with ions to flow from one fluid to another- resulting in a different life styles, thus contributing to the communica- change of charge in the fluid. tions problems which we know exist in the entertainment In the schematic of FIGURE 2. both the charge resistor and recording industries.

Complete information on STUDER Professional Audio Equipment and the name of the sales/ service representative in your area is available from, Willi STUDER America, Inc. Our new U.S. address is 1819 Broadway, Nashville, Tennessee 37203. In Canada, Willi Studer Canada, Ltd. Phone 416 -423 -2381.

Circle 34 on Reader Service Card PHILIP C. ERHORN

Scientific Calculators

Can't make up your mind which calculator to buy? Here are the facts, the whys and the wherefores, to help you make a wise choice.

SECONO- GENERATION hand -held scientific calculators, tesy of MOS Technology. Inc.. a prime supplier of a full now appearing on the market in increasing num- line of logic chips to the calculator industry. These key- bers, far outshine older "electronic slide rule" types. boards, utilizing forty single -purpose keys, illustrate iden- Most original versions lacked either scientific no- tical calculating facilities for each of the two logic sys- tation. parentheses keys, or both, seriously limiting calcu- tems. A single logic chip provide; all functions. with a lating power and readout capability. They are being 200 decade calculating and readout range. Included are dumped at low prices, but are in no way a bargain com- all the basic trig, log. and convenience keys to tackle pared to the full scientific models. Actually, prices on all almost any problem with comparative case and without scientifics have dropped impressively several times this past reference to a hook of tables. year, with many new models priced well below $100. Fur- The algorithms necessary for developing the equiva- ther price reductions may he imminent, as will he seen lents of such tables are built right into the calculator logic. further along. In the course of solving problems, the display may blank A word of warning in this respect. If you are consider- out for a second or two while the logic pursues some diffi- ing purchasing one of these intriguing, diminutive gems cult algorithm. Note that the RPN keyboard is distin- of technology, you will get just what you pay for. There guished by its ENTER key and stack roll key. The AES i; no substitute for quality. The cost of repairs to a bot- keyboard includes nested parentheses keys and an tom- line model may make it feasible to throw it away and EQUALS key. buy another. Reputable manufacturers are not interested in this kind of market, although they are making every at- The 4- register operating stack peculiar to RPN calcu- tempt to appeal to the vast student market, while still of- lators affords access to accumulated data or intermediate fering a reliable product at an affordable price. results, for either review or register exchange purposes. The stack roll key ] facilitates the operation. AES cal- BASIC TYPES culators offer only a register exchange key XHY which - here are two basic types of hand -held scientifics. The allows interchange of the entry (display) and prior result predominent one uses an algebraic entry system (AES), registers. not to be confused with our professional society of the Certainly most audio engineers should find these basic same initials! The other employs reverse Polish notation scientific features quite adequate for their problem -solving (RPN) as introduced and popularized by Hewlett -Pack- needs. Of course, calculating power and convenience will ard in all their scientifics, and now being adopted by a few be increased (price too!) as more features, such as con- other manufacturers. version, statistical, combinatorial, probability, and pro- Pictures speak more loudly than words, so two typical gramming keys, are added to the basics. Nevertheless, keyboard layouts arc reproduced here. through the cour- there are many more considerations before you can make a decision properly. For example, just what is RPN and how does it work?

HOW THEY WORK Philip C. Erhorn is a technical writer and consultant RPN is a parenthesis -free method of notation perfected Ñ from Stony Brook, N.Y. in relatively recent years by Polish logician Jan Lukasie- SCIENTIFIC NOTATION: Although data may be To change the sign of the mantissa, press the -I./ --j entered and displayed in standard notation with a key (change sign) before pressing EEX If the full floating decimal point, scientific notation (pow- - key is used after pressing EEX , the ex- ers of 10) is most convenient for handling very large ponent sign will he changed. To enter the decimal or very small numbers. The calculator will compute number 0.0000462 in scientific notation, move the and display numbers over a 200 decade range from decimal point 5 places to the right, and multiply by ±1.0000000 X 10- "" to ±9.9999999 X 10 The ". 105 (4.62 X 10-5): diagram shows the display format for scientific notation: Mantissa Exponent Enter Press Display - 1.2345678 --05I 4.62 EEX 4.62 00 5 I - 4.62 05 L- Decimal - I-- Exponent Sign Decimal Point - Integer If the equals key is now pressed. you will see the Mantissa Sign number revert to standard notation, 0.0000462.

The last two digits on the right end of the display You can mix data in scientific notation with data in are used for powers of 10 (exponents). To illumi- standard notation, including memory operations. The nate them, press the Enter Exponent. EEX key: calculator will convert for proper calculation: To enter the number 35.000,000 in scientific notation, move the decimal point 7 places to the left, and 12345 I 8.76 X 10"== 8772345 multiply by 107 (3.5 X 107) : Enter Press Display Important: Do not confuse ordinary exponents with 3.5 EEX 3.5 00 powers of 10:

7 3.5 07 25 - 32. 2 X l05 = 200,000.

wicz. As it is applied to hand -held calculators, the arith- keys) hierarchy must he observed between the paren- metic operations are entered after two or more operands thetical expressions, and so the answer 8.4 is correct. (numbers or parenthetical expressions) have been entered. Not surprisingly, the AES calculator will come up with the wrong answer (20.4) if the problem is entered as For example: (2 X 3) -4 (4 ± 5) X (5 - 2) = ? stated. To arrive at the correct answer (8.4) on either cal- Press Display culator, the problem should be stated as: (2 X 3) -I f(4 ± 5) X (5 2)) - 8.4 Ans.

2 ¡ Enter 3 6. ri ALGEBRA -WITH- HIERARCHY 4 [ Enter I 5 0.8 1 here are a few scientitics available which include built - 6.8 in algebraic hierarchy. These include the Canon F -7, of- 5 Enter 12 3. fering seven nested levels of parentheses plus hierarchy; all the Novus scientifics, offering hierarchy with RPN; and X 20.4 Ans. the Texas Instruments SR -50(A) and SR -51(A) which OR Press Display

2 I Enter 13 6. 4 I Enter 5_ 0.8 ALGEBRA or RPN` 5 I Enter 3. X 2.4 8.4 Ans.

Notice that intermediate answers are displayed each time you press a function key and no equals key is needed. Only numbers and results are stored. The first answer is incor- rect because the problem was entered without regard for the algebraic rule of hierarchy. This states that exponenti- Algebraic Entry Reverse Polish Notation Two Parenthesis Levels 4 High Operational Stack ation must he done before multiplication and division, Both With Full Scientific Functions Full Scientific Notations Full Feature Memory Twelve Digit Display which in turn must he done before addition and subtrac- tion. Parentheses must he employed where any part of this rule is excepted. While it is not necessary to enter paren- The two types of keyboards used in the theses with an RPN calculator (there are no parentheses calculators discussed in this article. The Melcor 635. Note the forty -key The Kingspoint SC -60. All basic The Hewlett-Packard 25. The smallest layout utilizing all single -purpose keys. scientific functions are directly of the calculators shown, this unit This unit can display exponents even available with the forty keys used. nevertheless performs all functions and though they are not shown on the The shift key must be used to utilize is additionally fully programmable even readout. supplementary convenience functions. though it has only thirty keys- almost all of which are triple purpose. Two shift keys (f and g) must be used to make basic scientific functions accessible. offer internally programmed sum -of- products capability AES with hierarchy, but no parentheses keys. in an effort to Press Display compete directly with RPN. This approach can often backfire. Without the option of [(2 ; + 3) El 5. parentheses keys, the internal hierarchy can work against (7 1 - 4) 3. you: (2 + 3) X 4 20. but the TI scientifics will treat 15. the problem as if it were written: 2 -i- (3 X 4) = 14, which is, of course, another problem. Additionally, the in- I(5 8) 13. ternal storage very registers of the popular SR -50(A) are 7. (9 - I 2) limited, and tackling a product -of -sums, or many other types of fairly complex problems will often entail using 91. paper and pencil, along with the memory, for recording X¡ 9.539392 intermediate answers. The otherwise very thorough instruction booklet fails to point out the real extent of such Log x 0.9795207 limitations. =1 15.979521 Ans. Ordinary algebraic logic with nested parentheses is far more obvious to use in any kind of problem, and eliminates the nasty tendency for mental laxity which I fell into with the programmed, hierarchal logic calculators, fre- With the RPN calculator, no parentheses need be en- quently leading me into some very wrong answers! I'm tered (remember, there are no parentheses keys) although happy to note that the new, magnetically programmable you must keep track of them in your head. This is suc- TI SR -52 includes keys for nine nested levels of paren- cinctly demonstrated by the final keystroke I + entered theses, along with its internal hierarchy. many keystrokes after its actual position in the problem. ENTER VS EQUALS Borrowing an example from a now obsolete H -P pub- You will notice a striking similarity in keystrokes be- lication entitled Enter vs Equals, we can observe a very tween the AES calculator and the RPN calculator. As a interesting comparison of keystrokes between an RPN matter of fact, the necessity for pressing the V-R-1 and I scientific, such as the most diminutive HP -21, and an Log x keys following the entry of the operands is ac- as AES scientific such the Melcor 635: tually RPN! It is also clear for both entry systems, des- [(2 + 3) X (7 - 4)] + [log V(5 + 8) X (9 - 2)] pite advertising claims to the contrary, that when trans- = 15.979521 cendental functions are involved in a problem, you cannot enter the problem from left to right, just as it reads. The RPN last batch of keystrokes certainly points this up. Press Display

2 3 5. With this two CO Enter 0 type of AES calculator, any -variable func- rn tion key ( +, -, X. =, Yx) during chain calculations, 7 I Enter' 4 3. completes any previous function instructions, the same as 15. EQUALS, as well as instructing the calculator what the C6 5 Enter 8 13. next function will be. With this fact in mind, the problem may be mentally a 9 2 7. Ené simplified as follows, reducing the total number of key- a Ix] 91. strokes from 30 to 24: R_ 9.539392 Lo x 0.9795207 2 +3 X(7 -4) + log J[5 +8X(9 -2)]_ m0 15.979521 Ans. 15.979521 Press Display scientifics. However, the addition of conversion and or statistical, etc. convenience keys means that some of the 2 3 177 5. keys now become dual -purpose. The second function is (7 ^ 4) 3. reached via a shift key. Recently, 10 addressable memories 15. and /or five or more levels of parentheses have been included in a few models, in particular the Kingspoint 6010, I5 R X 13. Melcor 655 and Melcor SCP -700. The chip affording 19 - 2) 7. these goodies interfaces readily with the basic logic chip, as does the just now being 91. ultimate programmer chip, offered. \X: 9.539392 Bear in mind while making a choice, that any calculator log 0.9795207 which uses multi -purpose keys to hold down costs, or to make it very compact physically, or because it offers in- 15.979521 Ans. creased convenience functions, will actually be less con- Learning this type of procedure is no more unorthodox venient to us. If you are fumble- fingered, use eyeglasses, than absorbing the methods of RPN. With a few evenings or need to use the extra features only occasionally, remem- of practice, you will become proficient with either type of ber that a 35 or 40 key, essentially single -purpose layout calculator, and its instruction booklet. is hard to beat. Within the practical limitations of the 4 -level operational The recent trend by Hewlett- Packard towards minia- stack in RPN scientifics, and two- nested levels of paren- turized scientifics such as the HP -21 and HP -25, demands theses plus operational storage registers for four numbers a keyboard using both dual -and triple -purpose keys. This and three functions in most AES scientifics, problems in- definitely increases chances for errors in entering data. volving multi- levels of parentheses usually must be tackled Operations will be slowed because you must look carefully from the inside out, in sections, just as we were taught in in order to press the correct keys. One or more shift keys high school algebra and trig classes. Of course those few must also be pressed in order to get at all the many fea- calculators, such as the Canon F -7, offering more than two tures offered on these multi -purpose keyboards. Get your levels of parentheses can be very convenient in avoiding eyeglass prescription updated or you will have trouble this sectionalizing mode of attack. However, even they reading the light blue designations on the sloping front do not guarantee that the problem may be entered from surfaces of the H -P compacts. Not to mention the tiny left to right, just as it reads. decimal points on the miniature LED red display. They are almost invisible in bright ambient light. MULTI -PURPOSE KEYS Solving problems of a far more complex nature than READOUT DISPLAYS those used here to demonstrate similarities and differences Speaking of readouts, you will find that the larger, between AES and RPN calculators will not faze the basic brighter fluorescent displays are showing up in some of

All 1/3 Octave Levels Are Not Recreated Equal!!! That is why professionals equalize recording studios, auditoria and special masking installations. But the job of equalization must not be left to your ears alone for they are neither calibrated nor qualified for sensing frequency -amplitude unbalance. Therefore, precision acoustic instrumentation must be used. Equalizing procedures require portable instruments which can be pow- ered internally. In addition, the equipment must be ruggedly con- structed to withstand the abuse of 1616 field environments. Who has the Third Octave 2306 equipment with a proven track record Filter Portable in the portability field? B & K has and Graphic Level we're waiting to prove it to you with Recorder our 2209 Precision Sound Level Meter, 1616 Third Octave Filter Set, and 2306 Level Recorder for hard copy proof of equalizing. Call or write 2209 today for complete details, at 5111 Precision West 164th Street, Cleveland, OH Sound Level Meter 44142 (216) 267 -4800. B &K Instruments, Inc &uel & Pn a on Instruments %61 4)

Circle 35 on Reader Service Card the new scientifics. Obtained primarily from the Orient, often contain mistakes and much oriental English. On the they have not been promoted aggressively, and have been whole, such booklets do a serious injustice to the calcu- in short supply. They usually come in shades of blue - lators which they describe. green, far more pleasing than the eye- fatiguing red of the Others, although inexpensively produced, are far better. usual small LED displays. They have been written by someone who not only knew Leds are solid state devices, while fluorescents are ther- math, but who was also psychologically in touch with the mionic, with a finite life, and subject to mechanical shock possible problems of the end consumer. Fortunately, a few such as dropping. So far, liquid crystal displays (lcds) of the larger manufacturers not only make a high quality have not been satisfactory for calculators. Most recently, calculator, (for which you will naturally pay a higher two new technologies, electrochromic and electrophoretic price) but also produce a high quality instruction manual, displays, are being urgently worked out by several manu- definitely not shirt -pocket size! Hewlett- Packard and Texas facturers, and could be a factor in hand -held calculators Instruments manuals are outstanding. They also offer sup- in the next two years. Meanwhile, if you have any eye plemental books filled with typical calculating examples. problems. stick with the fluorescents. WARRANTY PROGRAMMABLES Be sure to read the warranty. It tells you just what to do The final step up from the basic scientific calculator is (and sometimes what not to do) in the unlikely event that actually in two steps. Both steps lead to programmable you find a problem or two in the operation of your new units, but the ultimate product is the relatively expensive, calculator. Virtually all foreign -made as well as domestic magnetically programmed scientific represented by the scientifics have adequate stateside service facilities to back HP -65 and the newer, less expensive SR -52 from Texas up their warranties. You will find the construction of Instruments. The SR -52 promises even more features and most models to be quite exemplary, despite the trend to convenience than the HP -65. While these calculators may ever lower prices. This is a bonus of solid state technology. be programmed step -by -step, they both offer the rather in- credible facility (for a hand -held unit) of being able to TEST BEFORE YOU BUY program instantly by the insertion of a simple magnetic Before your buy, try to borrow a scientific so that you card. A selection of cards is part of the package, although can work out some of the problems in the instruction you can make your own. In addition, H -P offers a very booklet. Or visit the calculator counter in a convenient extensive library of cards to choose from. TI will no doubt store where you may stand a good chance of being al- quickly follow suit. lowed to play with several calculators and their instruc- As you read this. Melcor will be introducing their new tions long enough to firm up your decision. Unfortu- SCP -700, a manually programmable scientific to compete nately, most sales people do not have the background in with the HP -55 and 25, and the Novus 4525. At a break- math to offer much practical help. through price of $79.95, there will be serious repercus- After you buy, treat your new calculator as a valuable sions throughout the industry, and another round of price tool. Don't leave it lying around your lab or office, They reductions will have to take place. This substantial cal- are highly volatile, and will disappear almost instantly! culator is highly serviceable, and uses a 3 -chip set offering You might like a very inexpensive and handy calculator algebraic logic with five levels of parentheses. 10 inde- desk stand, the Cummins CalConvertor, found at most cal- pendent addressable memories, and 72 programming steps culator counters. Unfortunately the HP -21, 25, and 65 with direct and conditional branching. While it does not can't be fully used with any such desk stand. include some of the convenience features of the HP -25 Following is a brief listing of proven calculators in the and HP -55, it does offer a 40 key layout for maximum various categories, to he found at most calculator counters ease of operation. right now: Note that in all these calculators which can only be programmed step -by -step, the program is lost when the BASIC SCIENTIFICS calculator is turned off. This seems a small price to pay Melcor 635 for the great convenience offered. Kingspoint SC -20 Kingspoint SC -44(F) POWER SUPPLY H -P 21 (RPN) Be sure that your new scientific uses a rechargeable Rockwell 63R NiCd battery pack, preferably field- replaceable, such as TI SR -50 (A) those used in all TI and HP models, or in a plug -in cas- Novus 4520 (RPN) sette pack as in the Canon F -7. The cost of throw -away alkalines can be very significant over a period of time. STEP -BY -STEP PROGRAMMABLES NiCd's can be recharged hundreds of times, and a spare Melcor SCP -700 pack is indispensible when you are travelling. HP -25 (RPN) The a.c. adaptor charger supplied will let you use your HP -55 (RPN) calculator on a.c. However, some manufacturers advise Novus 4525 (RPN) minimizing a.c. usage in order to avoid shortening of the battery life through possible overcharging. Be guided by SCIENTIFICS PLUS CONVENIENCE the particular instructions provided in the instruction FEATURES booklet. Canon F -7 H -P 45 (RPN) INSTRUCTION MANUALS Melcor 650 and 655 You will find that there is a tremendous difference in the Kingspoint SC -60 and SC -6010 quality of the instruction booklets or manuals packed with TI-SR-51(A) scientific calculators. Most manufacturers seem to feel Corvus 500 (RPN) that they should be shirt pocket size, and the average book- PROGRAMMABLES let of this type is very basic, leaving entirely too much to MAGNETICALLY your imagination. Many are readable only with a magni- TI SR-52 N co fying glass, particularly the calculating examples. They HP-65 (RPN) SIDNEY L. SILVER

The Dynamic Control Of Sibilant Sounds

De- essing techniques require awareness of the nature of speech, careful timing, and exact control.

ODERN, SOIIISTICATED sibilant control devices perform a useful function in automatically controlling sibilant voice levels in film, tape and disc recording operations. Performance specifications have greatly improved, so many of the diffi- culties associated with older units, such as gain "pumping," breathing effects, and audio holes have been virtually elim- inated in the new designs. These anti -sibilance devices, or de- essers, were first introduced in the motion picture industry to handle an annoying problem -the inherent susceptibility of optical sound tracks to sibilant distortion. Cinema sound engineers found that the use of volume compressors to solve dynamic range problems would tend to accentuate sibilant sounds and up- set the normal spectral balance between high- and low - frequency speech components. This phenomenon, which has been termed "spectral energy distortion," manifests 100 200 500 1000 2000 5000 10 000 itself as an unpleasant harshness accompanying the sibilant FREQUENCY (Hz) consonants. At times, these sibilant levels are strong enough to severely overload the audio system, producing intoler- Figure 1. The spectral energy distribution curve for able spitting sounds across most of the voice- frequency speech. hand. In order to deal with this problem, frequency- depen- dent program conditioners have been developed to de -ess or dynamically control high -level sibilant peaks so that the compressed output the system most the natur- of retains of In recording operations, the difficulty arises because of alness of the voice. past years, de- essers original During the large amount of volume compression often applied to have not been utilized tape and disc extensively by the vocal tracks to raise the apparent loudness of the finished recording industries because of their failure to meet the record. Also, the practice of using presence equalization high standards set by quality- studios. conscious recording to enhance the listening value of many recorded singing But now that de- essing devices are available without the voices tends to boost sibilant levels excessively. There is no undesirable side -effects that plagued the earlier versions. doubt that these speech processing methods could be uti- there appears to he no valid reason why large quantities lized to maximum advantage by incorporating some form of recorded vocal material are still being with released of dynamic sibilance control into the system. raspy sibilant sounds. But even in situations where uncompressed speech sounds are recorded and vocal dynamics retained, over- empha- sized sibilance is often observed, especially during close - Sidney L. Silver is on the supervisory staff of the miking work. Some voices, for example, have whistling Telecommunications Section of the United Nations, where tones which generate sibilance distortion when using cer- he is in charge of sound and recording. tain microphones, while others do not sound sibilant at all. SIBILANT DE- ESSED VOICE IN VOICE OUT 10

CURVE FOLLOWED BY O, LOW-FREQUENCY SIGNAL

I I VARIABLE

CURVE FOLLOWED BY HIGH FREQUENCY - ';,/ - SIGNAL THRESHOLD GAIN CONTROL CONTROLLING 4 ELEMENT -6 -2 0 2 4 6 8 10 12 14 16 18 20 Figure 2. A simplified b lock diagram of a de -esser INPUT LEVEL (dB) system using control-path equalization.

Figure 3. The compression characteristic of a de -esser indicates threshold sensitivity as related to various frequencies.

Subjective experiments have confirmed that a more natural and pleasing reproduction of the speaking voice and singing voice can be achieved if the tendency toward exaggerated sibilance is minimized. Before discussing in detail the various de- essing techniques available to the recording engi- SPECTRUM LEVELS IN SPEECH neer, it would be useful to review some of the acoustical As a basis for understanding the fundamental aspects of properties of sibilant sounds. sibilance control, it is important to have a knowledge of the spectral energy distribution of speech signals. Speech THE NATURE OF SIBILANCE is staccato in nature, the amplitudes and frequencies vary- From the standpoint of acoustics, speech may be re- ing continuously, with pauses between syllables, words and garded as a continuously changing sequence of complex sentences. Moreover, there are characteristic differences waves that vary widely in spectral composition and over- between the speech sounds of men and women, as well as all level as a function of time. The vowel sounds carry individual variations in voice patterns. The problem of de- most of the energy of the voice, while the sibilants (as termining the relative energy content must therefore be well as other consonants) provide most of the information approached statistically by performing sampling measure- needed for high intelligibility. To generate a sibilant sound, ments of the voice in specific frequency bands covering an air stream is forced through a narrow constriction the entire speech spectrum. formed by the articulators at some point along the vocal On this basis, Dunn and White' accumulated data on tract. When the air column reaches a sufficiently high the rms pressure patterns of normal conversational speech, velocity, the resultant friction causes the air to become indicative of the power or energy levels. From this data, a turbulent and a high- frequency hissing sound is created. smoothed -over curve was derived (FIGURE 1), representing For example, the sibilant consonant s, as in the word see, the average spectral energy distribution of the measured is characterized by a harsh, rushing sound formed by the rms pressures reduced to a one -hertz band. It can be tongue against the upper gum ridge. If while this sound clearly observed that most of the speech energy is concen- is being produced, the tongue is lowered slightly and the trated in the low- frequency range below 1000 Hz. For the vocal cords brought into play, the acoustic output becomes average individual, it can be assumed that the ratio of a voiced z, as in the word zoo. A lower -pitched hiss re- strong vowel sounds to weak consonant sounds is about sults when the tongue is placed against the hard palate to 20 dB. This is an important consideration because the form the unvoiced sh sound, as in the word she. Then if equalization characteristics of de- essing devices take into the air outlet is adjusted for a less restricted opening in account this speech energy curve in the suppression of the vocal tract and the vocal cords actuated, the sibilant sibilants (This will be discussed in a later section). output becomes a voiced zh, as in the word azure. De- The foregoing data deals with the objective aspects of pending upon the size, shape, and positioning of the statistical voice signals but provides no direct information articulators during the production of speech sounds, there as to the manner in which the hearing mechanism evaluates will be some individuals with pronounced sibilant voices the loudness of speech. Experience has shown that the and others with only moderately sibilant vocal character- ear integrates speech sounds over a period of time, so that istics. loudness perception is proportional to the rms value, or There are other speech sounds which have similar reson- actual energy level, rather than the peak levels of the ant conditions as the sibilants, differing only in duration voice. As far as the listener is concerned, the frequency and intensity. These are the unvoiced stop consonants pro- response of the auditory system is characterized by a produced by making a complete closure in the vocal tract, nounced peak in the 3500 Hz range at moderate listening building up pressure, and then abruptly releasing the air. levels. This increased sensitivity of the ear in the sibilant The resultant explosive sounds, exemplified by all of the region means that speech intelligibility will not be im- consonants in the word pitch, are sharp transients which, paired even though the information -bearing consonant unlike the sibilants, cannot be sustained. All of these vocal energy level is appreciably below that of the vowel energy. sounds described above, whether sibilant consonants or Because of this compensating effect, however. high -fre- unvoiced stop consonants, are a constant source of annoy- quency vocal sounds are particularly bothersome to the el ance to recording engineers. listener in situations where sibilance is grossly exaggerated. ANTI -SIBILANCE TECHNIQUES an octave above and below that range. Under these con- In vocal -pickup arrangements, there are certain correc- ditions, attempting to suppress high -level sibilant peaks tive measures that can be taken with regard to microphone by acoustical or electrical filtering would lead to colora- selection and orientation, so as to reduce the audible ef- tion of the voice signals. The best approach is to control fects of excessive sibilance and explosive sounds. One point automatically sibilant levels by frequency- sensitive com- where is applied to consider is the action of the air stream from the mouth pressor action, gain reduction selectively (and nose) on the generating element and casing of the to the entire range of speech components without any ap- microphone, producing unwanted breath noises accom- parent roll -off of high -frequency response. panying the speech sounds. GENERALIZED DE -ESSER SYSTEMS For close talking and close -singing work, therefore, om- Let us first consider how sibilants are affected when a nidirectional microphones may be preferred because of conventional volume compressor is used to reduce the their inherently low sensitivity to breath puffs and ac- dynamic range of voice signals. Recall that sibilant con- centuated sibilance, as compared to their cardioid counter- sonants are composed of high -frequency components with parts. Here an advantage is gained from the fact that the low -level energy, while the vowels are predominantly low - undesirable components of the air velocity are consider- frequency components with high -level energy. Conse- ably more directional than the speech sounds being trans- quently, there is a good probability that the high- frequency mitted with them. By having the soloist performer work sibilants will not be powerful enough to trigger compressor across the microphone into it, omni rather than directly action to the same extent as the low frequencies. say, 45 degrees off -axis, the effects of breath noise can As an example, suppose that a speech sound is initiated thus be diminished. This can easily be accomplished with- with a sibilant consonant and followed by a vowel. In out taking too much "edge" off re- the high- frequency accordance with the voice energy curve shown in FIGURE sponse of the pickup. Breath noises also be suppressed can I. the compressor will not be actuated by the initial con- by covering the with a entire microphone suitable acous- sonant but rather by the subsequent vowel. The resultant tically transparent shield. Such a breath screen will pro- effect is that the relative spectral energy distribution will duce a high degree of attenuation to breath- excited pres- be altered so that the amplitude of some sibilant sounds is sure variations, while only slightly affecting the speech substantially higher than that of the vowels. sounds arriving at the microphone. Over -emphasis of these sibilants will occur during the In general, these procedures are effective in reducing time the compressor happens to be in a state of equilibrium many explosive vocal sounds, but do not always work suc- due to relatively long pauses or widely fluctuating levels. cessfully when the "essiness" of strong sibilant sounds is In the most extreme cases, the sibilant overload will give perceptually dominant. Although the sibilants are concen- rise to a form of frequency -selective amplitude distortion trated in the high- frequency vocal region (about 3500 Hz), which the ear perceives as an unnatural splatter of sibilant there are secondary component peaks extending more than sounds. Once recorded, this condition cannot be corrected ONE EQUALS TWO With the Sound Workshop Model 220 VOCAL top rated 882M, at $1500, is a full studio or PA DOUBLER, one piano, one voice, one drum set. console, with 8 inputs and 2 outputs (plus direct become two. Or five sounds become ten. Or mono outputs on every channel for multitrack recording), signals expand into stereo. The Sound Workshop EQ, panning, echo and monitor sends, first stage 220 is the tool; your creativity is the means. trim control, line /mic switching, output meters, complete monitoring facilities, and our unique C found Wprtihop > transformerless mic input circuit that provides exceptional transient response and ultra -low distortion. For $1200, the 882 provides the same features and performance, but without the meter/ monitor panel. Our new model 840 is a four out The Sound Workshop Model 220 VOCAL version, offering the same studio performance for DOUBLER is an analog electronic delay line, which just $850. uses the latest charge coupled integrated circuits. We also build electronic crossovers, disco mixers, The delay time is continuously variable from 5 and a host of other useful studio accessories, all milliseconds to 40 milliseconds. Internal mixing is with the Sound Workshop philosophy of high quality, provided to allow its use with any system, from a with a not so high price. simple tape deck or PA system,to the most complete Sound Workshop Professional Audio Products studio set -up. At $500, it just might be the best carry a two year parts and labor warranty, and are bargain on the pro-audio scene. available from a growing number of qualified audio And speaking of bargains, the Sound Workshop dealers. 242 Stereo Reverberation System has become the For complete information about our products, new standard for inexpensive reverb units. A lot of circle the number below on the reader service card, great sound for just $375. drop us a line, or give us a call. All Sound Workshop products reflect our philosophy of designing and manufacturing studio quality products at less than studio prices. .>SoundoUlörkshop For example, our line of recording /PA mixing consoles provides unprecedented performance. Our bringing the technology within everyones reach w Audio by Zimet , 1038 Northern Blvd., Roslyn, Long Island, N.Y. 11576-(516) 621 -0138 Circle 36 on Reader Service Card reduction action may produce waveform distortion. Fur- thermore, in situations where the operating levels are apt to fluctuate widely, e.g., cinema dialogue, stage presentations, etc., a proportionately greater amount of de- essing would be perceived on loud sibilant sounds than on weak ones. To offset these limitations, a commercially available dynamic sibilance controller has been developed (FIGURE 4) which automatically adjusts its threshold level in propor- tion to the peak level of the program material. In effect, Figure 4. The Orban /Parasound model 516EC Dynamic the control threshold is able to track the high- frequency Sibilance Controller provides three independent peaks where de- essing starts to occur, so that the de- channels for de- essing. essing action remains essentially constant with changes in program level. Depending upon the setting of the threshold control, this relationship is maintained for input levels varying over a range of 15 dB. The device is equipped with three independent de- essing channels, allowing the by any fom of signal processing during reproduction. It can operating parameters of each unit to he optimized to the he avoided if the compressor is made to follow a fre- individual vocal source. quency- versus-level curve that matches the spectral characteristics of the vocal sounds. TIMING CHARACTERISTICS Various schemes have evolved over a period of years De- essing devices are characterized by a fairly rapid re- for de-essing speech signals for recording. At the present duction of gain at the onset of high- frequency sibilant time. it is common practice to introduce compact -size com- peaks and a relatively slow restoration of gain after the pressor limiter combinations into separate vocal micro- peaks have subsided. Ideally, these units should provide phone channels ahead of the main audio mixing console. frequency- sensitive compressor action with negligible spec- Included in each unit is a built -in facility for switching a tral energy distortion and have attack and release times de -ess equalizer into the control circuit. allowing the mixer that ensure a smooth inaudible transition between the gain - to select what he considers to he the proper amount of de- reducing state and the constant -gain condition. The attack essing for each microphone. time should be fast enough so that compressor action is FIGURE 2 shows a simplified block diagram of a sibi- effective on the leading edge of transient sibilant peaks lance control system using level compression and peak without the danger of overshoot. limiting to provide frequency-selective gain reduction in If the transients persist over a sustained period, serious the de- essing mode. Here the speech imput is channelled waveform distortion will result during the brief intervals through a preamplifier, a variable -gain stage (vgs), and an before gain reducticn takes place. However, it has been output amplifier. both amplifiers providing the necessary observed experimentally that the average listener will not operating levels and isolation for the vgs. In operation, a be able to detect such distortion if it lasts for less than sample of the output signal is passed to a de -ess equalizer IO ms. On the other hand, too long an attack time will to emphasize the high -frequency components. The equal- permit the steep wavefront of short sibilant bursts and ized audio is then applied to a gain- controlling vgs derived explosive sounds to be overemphasized at the beginning of from the program material. Circuit parameters of the gain words and syllables, with system gain being subsequently controller determine the timing characteristics of the con- lowered on succeeding portions of the voice signals. For trol signal and its effect on the threshold level. proper de- essing action, an attack time on the order of In effect. the system is a closed loop type of control one millisecond will allow sufficient time for sibilant tran- which. being degenerative, acts to reduce system gain as sients to decay without any adverse effects being perceived. the frequency- dependent program level is increased above The problem of release time is a more complex one a certain threshold. Since de -ess equalization is used in the governed by the type of program material involved, i.e., closed loop, there will he a progressive rise in gain with speech or singing, and also the subjective judgment of the increasing frequency above the verge of compression. As operator. For these reasons, de- essers sometimes provide shown in FIGURE 3. each frequency component follows a a choice of recovery time values. With an extremely short different compression characteristic. so that gain reduction release time, the rise in system gain between words and is made relatively greater for high- frequency sounds. syllables tends to exaggerate breath noises on certain sibi- Hence, normal energy distribution of the voice signals is lant consonants prior to the resumption of vocal signals. restored at the output. This holds true because the de -ess Also. gain recovery may occur during a sibilant peak equalizer characteristic is based on a complementary ver- rather than after it, so that the final portion of the transient sion of the speech energy curve given in FIGURE 1. is accentuated. should In practice, it has been found that much better results To avoid this type of distortion, recovery time be postponed all of the sibilant peak has can be obtained by using a steep- rising curve in the high - until practically experienced gain with too slow a re- frequency vocal region with a slope of say, 18 or 24 dB reduction. Operating the material to undergo per octave. This configuration enables the de -esser to dif- covery time will cause program ferentiate between the sibilants and high -level low -fre- prolonged gain reduction following some isolated sibilant quency components, thereby eliminating the possibility of peak, with gain restoration taking place too late to be ef- spurious triggering by low- frequency information. fective against immediately occurring peaks. In general, can be the new gain. It should be noted that the appropriate timing charac- satisfactory de- essing achieved if is held 15 ms teristics and compression slopes for de- essing and normal and hence release time, for approximately before is volume compression are not the same. Therefore, merely it allowed to recover. connecting a high -pass equalizer in the control circuit of a standard compressor does not mean necessarily that the REFERENCE de- essing function will be performed satisfactorily. Unless I. Dunn, H. K. and White, S. D. Statistical Measurements in the available attack and release times and compression ra- Conversational Speech. Journal of the Acoustical Society of tios can be adjusted for optimum sibilance control, gain America. vol. 11, Jan. 1940. pp. 278 -288. ONE STOP .'Ja{assIeY FOR ALL YOUR PROFESSIONAL AUDIO REQUIREMENTS BOTTOM LINE ORIENTED Closing date is the fifteenth of the second month preceding the date of issue. Send copy to: Classified Ad Dept. F. T. C. BREWER CO. P.O. Pensacola. db THE SOUND ENGINEERING MAGAZINE Box 8057, Fla. 32505 1120 Old Counry Road, Plainview, New York 11803

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Gately ton Bridge. Professional Audio Video Electronics, 57 W. Hillcrest, Havertown, Corporation, 342 Main St., Paterson, Pa. 19083. (215) 449 -6400. N.J. 07505. (201) 523.3333.

WANTED

USED CASSETTE DUPLICATORS. Many Neumann recording console, 18 input, WILL TRADE SYNTHESIZERS for pro- brands and models to choose from. All $14,000 (originally $35,000). Scully 8- fessional audio and video equipment. rebuilt and warranted. Infonics, Re- track with remote control, can be ex- New Electron Farm -CBS Buchla syn- cordex, and Pentagon. Write for list and panded to 12 tracks, $7,000. Neumann thesizers for: multi -track decks and specs. Tape and Production Equipment lathe with Westrex 2 -B mono system electronics, amplifiers, monitors, mic- Company, 2080 Peachtree Industrial plus accessories, reasonable. Pentagon rophones, mixing consoles, etc.. video Court, Atlanta, Georgia 30341. cassette duplicator, reel /cassette, cassette /cassette, $1,000. Ampex AG -500 decks. cameras. monitors, etc. Gregory stereo, $1,250. Ampex PR 10 stereo, $600. Kramer, Electron Farm, 135 W. Broad- Paul. (312) 225 -2110. way, New York, N.Y. 10013. (212) 349 -0098. Los Angeles (213) 396 -6339. $2 MILLION USED RECORDING EQUIP- MENT. Send $1.00 for list, refundable, to The Equipment locator, P.O. Box 99569, WANTED: ECM -22 ECM -377 DECOURSEY ELECTRONIC SONY and San Francisco, Ca. 94109. microphones. Blue Diamond Co., Box CROSSOVERS 94109. 102C Chubbic Rd., R.D. 1., Canons- Complete with plug -in Butterworth filters burg, Pa. 15317. (412) 746 -2540. of your specified frequencies and with 6, 12, or 18 dB /octave attentuation; regulated power supply; bi -amp or triamp for monaural, stereo, or quadriphonic INTERESTED IN BUYING complete stu- MONITOR EQUALIZERS for your Altecs systems. Other options: electronic sum- dio. Contact Bradley Recording Com- mer for woofer VLF noise & J.B.L.s are a steal at $75 /channel single stereo; pany, 531 N. Howard St., Baltimore, filters. For OEM and home builders: Maryland 21202. 500 and 600 Hi -pass and Low - FREE ROOM EQUALIZATION with pur- Series chase of th octave filters. This is not pass filter pairs. Also regulated power supplies. Write for brochure. DeCoursey a misprint. Music It Sound, Ltd., 1P/2%2 WANTED, J.B.L. pro dealers to handle Engineering Laboratory, 11828 Jeffer- Old York Rd., Willow Grove, Pa. 19090. high end multi -channel consoles on ex- son Blvd., Culver City, Ca. 90230. (215) 659 -9251. clusive basis. Designed to augment J.B.L. S.M.E. Damping Mods -$30.00 pro line of speakers and amplifiers. Theatre Sound, Inc. P.O. Box A.Q., New Haven, Conn. 06525. MCI input modules, $550.00 each. Test- ed and Guaranteed. Paul. (312) 225- 2110. MCI . . . DOLBY. Two great names! WANTED: Studer model A -80. Para- Two great products! For authorized fac- mount Recording Studios. (213) 461- tory representation in the progressive 3717. Midwest, contact: Jerry Milam, Milam Audio Co., 1504 N. 8th St., Pekin, Ill. ALTEC /H -P 8050A 1/3 octave band CRT 61554. (309) 346 -3161. display audio analyzer. Ideal for room equalization, $2,800. Lewis S. Goodfriend 8 Associates, 7 Saddle Rd., Cedar Knolls, N.J. 07927. (201) 540 -8811.

AUDIO BEEPER, new low cost model for all audio -visual systems. Call or EMPLOYMENT write C- TRONICS, P.O. Box 84, East Brunswick, N.J. 08816, (201) 254 -9487. 16 x 16 CUSTOM CONSOLE, Spectra - sonic components, $12,500. Four Shure EXPERIENCED MUSIC MIXER M67s, four M63s, one M68, one M688 stereo mixed with four pan pots assem- For major N.Y.C. studio, expand- bled as four -track console, $800. Fifth ing staff. Send resume to Box 11, 3/M 16 -track tape recorder, M -56, Floor Studios, 517 W. Third, Cincinnati, db Magazine, 1120 Old Country $14,500. Perfect. Paul. (312) 225 -2110. Ohio 45202. (513) 651 -1871. Rd., Plainview, N.Y. 11803. 0 o peop/pces/happenings

of vice president of industrial relations. Ms. Keller's responsibilities will focus on labor relations. She was previously associated with Transconti- nental Music Corp.

Juan C. Gregorio has joined Mc- Martin Industries, Inc. of Omaha. Ne- braska. Mr. Gregorio will be involved in the development and design of new a.m. and f.m. broadcast transmitters. MARTIN BURNETT ROBINSON BETHUNE He comes to McMartin from Sparta Electronic Corp.

A number of personnel changes Regent Industrial Center in Elk Grove Frank Rush has been appointed as have made news at the Koss Corpora- Village. Illinois. The new facility will senior field sales engineer in broad- tion. of Milwaukee. Wisconsin. Ced- house corporate offices, training and cast video sales for the Ampex Cor- ric R. Bastiaans has been promoted showroom facilities. as well as serve poration. Based in Bethesda. Mary- to vice president. engineering. Mr. as a distribution hub. land. Mr. Rush will handle the terri- Bastiaans. who was formerly chief en- tory of Pennsylvania, Maryland. Dis- Two appointments have been an- gineer at the company. came to Koss trict of Columbia. Virginia. and West nounced by James B. Lansing Sound, from Westinghouse. Jeffrey T. Martin Virginia. Rollin Stanford, based in Inc. of Los Angeles. Bill Robinson has been named regional sales man- Hackensack. New Jersey. will succeed has assumed the position of national ager for the company's stereo head- Mr. Rush as sales engineer for dis- sales manager. consumer division. and phone products. Michael A. Makowski tributor products. and Russell Wells have joined Koss Dick May is filling the newly estab- as consumer products salesmen in the lished position of product manager. A new head office and laboratory midwest territory. Dan Reep, coming Mr. May will he responsible for new has been opened by Dolby Labora- from the Milwaukee Gear Co.. has as- product development. tories, Inc. in San Francisco at 731 sumed the position of director of in- Sansome St. The new telephone num- dustrial relations. Joseph J. Chladil, The recent appointment of Ed Beth- ber is (415) 391 -8892. This facility Sr., previously manager of new prod- une as vice president of engineering has will replace the New York office. uct development. has been promoted been announced by Infonics, Inc. of which has closed out, and also en- to the position of manager of new Michigan City. Indiana. Mr. Bethune compass some of the functions of the product development and engineering. comes from Aleph Industries. Infonics London office. The new office will has appointed Cassette Systems, of handle research and development. new Woodstock. Robert F. Burnett has been named Maryland. as the mid - market development. licensing and sales manager. retail market, for the Atlantic regional service center for U.S. sales. San Francisco executives Magnetic Audio Video division of the Infonics tape duplicator equipment. will comprise Dr. Ray Dolby, pres- 3M Company, St. Paul, Minn. Mr. ident; David Robinson, vice president. Trundling through the Colorado Burnett has been with 3M since 1961. engineering: loan Allen, vice presi- Rockies is a truck, hearing a complete dent. marketing: Ian Hardcastle, vice mobile recording studio. an affiliate Rev ox Corporation and Lamb Lab- of president. licensing: and John Gladys - oratories of Syosset. N.Y. have put Road Runner Recordings, based at iewicz, vice president. finance and ad- together mobile recording studios Evergreen. Colorado. The mobile unit ministration. George Schowerer, oper- which can he rented through Revox is available for 4 -16 -track recordings ating from New York. will supervise on location. dealers. Two sizes are available, a East Coast Dolby projects. mini studio which contains the basics. Joseph S. Tushinsky of Superscope, and a maxi studio. comprising a more A ranch -ype building in the lush Inc. was honored recently at the sec- complex assortment of equipment. The Mother Lode country of Northern ond Audio Hall of Fame awards din- combination can also he purchased. California serves as the new head- ner held in Los Angeles. Sponsors of quarters for the Herold Broadcasting the were A patent for a new process. "Tran- dinner Time, Audio Times, Company (KVML 'KROG). of So- scan." has been awarded to Goldmark and Stereo Review magazines. Pro- nora. Ca. The station beams to terri- went Communications Corp. of Stamford ceeds of the dinner to the City tory made famous in Gold Rush days. Conn. Transcan optically transforms of Hope. fabled Tuolumne. Calaveras, and parts picture images recorded on wide - Richard P. Goodwin has been ap- of other adjacent counties. screen motion picture film without dis- pointed plant manager of National torting them to fit viewing windows PSI Industries of Rye. N.Y., a Tape Service in W. Caldwell, N.J. Na- of home television sets. The process new corporation owned prinicipally tional Tape Service is a subsidiary of uses a special "Panamorphic" lens de- by S.A. Nastro, has purchased Pre- RKO General of New York. Mr. veloped in conjunction with Pana- ferred Sounds, Inc. from Longine -Witt- Goodwin was formerly project engi- vision. Inc., of Hollywood. nauer. Jerry H. McPherson will serve neer for Mastro Industries. as president of Preferred Sounds. Vice - A new national American head- Audio Magnetics Corp., of Gar- president of marketing is John W. quarters for Danish -based Bang & dena, Ca.. has announced the promo- Barry, coming from the Infodex Cas- ° Olufsen has been established at the tion of Mary A. Keller to the position sette Corp. Handling all this is a lot easier. When you can take this for granted.

The new Electro -Voice DS35 Cleaner highs, wider response: abuse -even remotes and Single -D Cardioid. The exclusive dia- road tours. The pneumatic The performance mike phragm design assures lin- shock mount absorbs hand that makes your job go a lot ear motion to reproduce and cable noise. The integral more smoothly, no matter more accurately, especially blast filter squelches "P -pop- how big a job you've got to at frequency extremes. And ping:' And it's protected by handle. state of the art port design the famous E-V professional Greater gain before feedback: means the best off -axis re- warranty. Check it out yourself. sponse of any single -D mi- Work your system with a crophone. DS35...$90.00 Suggested Re- DS35. Compare the level you More boost to the bass: sale Net. Slightly Higher in West- ern States. can get before feedback with Used close up, the DS35 that of any competitive mike. supplies lots of the bass One big reason is the flat re- boost (proximity effect) some Electrol/oice sponse provided by our entertainers want. uniqueVolumetric1M laminated Stronger and quieter: a.sultan company diaphragm- designed with The rugged steel case Dept. 261 BD, 686 Cecil Street the aid of laser holography. withstands the toughest Buchanan, Michigan 49107 circle I ! can Reader .Service Card The Model 5, less than $1500.00*

For recording or reinforcement, at home or on the road, wherever the music is, the Models can help you make it better. Eight inputs. Each with attenuation controls, LED overload indication, two foldback sends - one before and one after the EQ and fader - two bands of EQ -4 selectable frequencies, i-15 dB of boost or cut - solo, direct out, channel assign & pan. The mic inputs are low impedance, balanced, transformer isolated. Four Submasters. Each with buss /tape monitor, tape cue, monitor pan and gain for an independent stereo monitor mix, and echo receive gain which can be assigned to the monitor buss only, or to the program buss as well. 'Actual resale prices are determined individually and at the sole discretion Multiple patch points. 3 provisions of authorized TEAC Tascam Series dealers. for headphone feeds; switchable output levels; accessory send /receive on each input; buss in on each output; plus cascade facilities for interconnecting two Model 5's. Fully modular, portable, and quiet (the equivalent input noise is 125 dB). So if you have more talent than money, check out the Model 5 at your nearest TEAC Tascam Series dealer. Just call toll free (800) 447 4700 ** for the name and location of the one nearest you. **In Illinois, call (800) 322 -4400. T EAC® TASCAM SERIES