M a y-A u gu st 1982 POLUPHONU $2.50 ELECTRONIC MUSIC & HOME RECORDING ISSX: 0163-4534

ANATOMY OF A PRIVATE RECORD

recording

promotion

AN INTERVIEW A DIGITAL FILTER WITH DON SLEPIAN OPTICAL AUDIO CONTROL THE ULTIMATE KEYBOARD

The Prophet-10 is the most complete keyboard instrument available today. The Prophet is a true polyphonic programmable synthesizer with 10 complete voices and 2 manuals. Each 5 voice keyboard has its own programmer allowing two completely different sounds to be played simultaneously. All ten voices can also be played from one keyboard program. Each voice has 2 voltage controlled oscillators, a mixer, a four pole low pass filter, two ADSR envelope generators, a final VCA and independent modula­ tion capabilities. The Prophet-10’s total capabilities are too The Prophet-10 has an optional polyphonic numerous to mention here, but some of the sequencer that can be installed when the Prophet features include: is ordered, or at a later date in the field. It fits * Assignable voice modes (normal, single, completely within the main unit and operates on double, alternate) the lower manual. Various features of the * Stereo and mono balanced and unbalanced sequencer are: outputs * Simplicity; just play normally & record ex­ * Pitch bend and modulation wheels actly what you play. * Polyphonic modulation section * 2500 note capability, and 6 memory banks. * Voice defeat system * Built-in micro-cassette deck for both se­ * Two assignable & programmable control quence and program storage. voltage pedals which can act on each man­ * Extensive editing & overdubbing facilities. ual independently * Exact timing can be programmed, and an * Three-band programmable equalization external clock can be used. * Program increment footswitch * Ability to change programs automatically in * Programmable volume control and a master the sequence. volume control * Transpose facilities for instant pitch * Octave transposition switches changes. * Upper & lower manual balance control * A-440 reference tone The Prophet-10 comes complete with a high quality flight case, two voltage pedals and two foot- switches. It’s now available; see your local dealer. Play the Prophet-10 today —It’s your ULTIMATE KEYBOARD.

For more information write to: SEQUENTIAL CIRCUITS, INC. 3051 North First Street Dept. K San Jose, California 95134 STAFF CONTENTS ISSN: 0163-4534

PUBLISHER Volume 7, Number 6 John S. Simonton, Jr. May/August, 1982

EDITOR Craig Anderton

MANAGING EDITOR Linda Kay Brumfield Anatomy of a Private Record By: Robert Carlberg...... 8 Technical Illustrator Caroline Wood Component Profile: SSM2033 & SSM2044 By: Tom Helfrich...... 36 CIRCULATION Ramona French Electronic Sound Pistols Peggy Walker By Dr. Andrew Gelt...... 21

BOOKEEPING Interview: Don Slepian Cathi Diehl By: Don Schwartz...... 10

PRINT PRODUCTION Optical Audio Kay Schwartz By: James Lisowski...... 34 SEMCO Color Press The Phase Checker By: Craig Anderton...... 14 POLYPHONY (ISSN 0163-4534) is published bimonthly at 1020 W. Wilshire Blvd., The Realistic MG-1 Synthesizer -Review Oklahoma City, OK 73116, by Polyphony By: Chuck Pogan...... 31 Publishing Co. Entire contents copyright (c) 1982 by Polyphony Publishing Co. All Remote Switching for DOD 500 Series Processors rights reserved. No portion of this publication may be reproduced in any By: David DiFrancesco...... 41 manner without written permission frpm the publisher. Second Class postage is The Syn-Bow paid at Oklahoma City, OK 73125. By: Ron Minemar...... 18

ADVERTISING_ rate card and deadline Understanding Digital synthesizers: schedule is available upon request. Contact Linda Brumfield at (405) A Digital Filter 842-5480. By: Dave Wilson...... 26 DEALERS & DISTRIBUTORS bulk prices are available upon request. Contact Linda Brumfield at (405) 842-5480. SUBSCRIPTION rates: Applied Synthesis American 1 year $12.00 By: Bill Rhodes...... 6 2 years $22.00 Foreign 1 year $14.00 Details: 2 years $26.00 We now accept MasterCharge and Visa By: Dennis Bohn...... 39 payment for subscriptions, back issues, ana PolyMart items. Foreign payments Practical Circuitry must be by charge card, money order, or By: Tom Henry...... 16 certified check in US funds drawn on a US bank. Re-View BACK ISSUES are available at $2.50 each By: Robert Carlberg...... 15 ppd. Send SASE and request pur ’Back Issue List' for a complete index of issues and their features, or see the back issue ad in this issue. CHANGE OF ADDRESS notifications must include your former address and zip Ad Index...... 32 code, and any numbers from the mailing Current Events ...... 24 label, as well as your new address. When you move, be sure to notify your Editors Notes ...... 4 post office that you DO want second Equipment Exchange ...... 42 class and controlled circulation publications forwarded. This will save Letters ...... 5 lost or returned issues. Polyphony is Index to Volume 7 ...... 33 not responsible for replacement of lost or returned issues when we have not been supplied^ with change of address This is a special double issue. It spans the four information. Summer months from a time standpoint but counts as TO POSTMASTER, send address changes to: only one issue towards subscriptions. POLYPHONY PO Box 20305 Oklahoma City, OK 73156 Ph. (405) 842-5480

POUPHONU March/April 1982 3 "Unauthorized duplication is a violation of types of tape recording equipment. In fact, I re­ existing laws". Those eight words are creating cently received a letter from ASCAP urging me to reams of controversy, what with the matter of video support the bill being proposed in Congress to taping currently in court, and the record industry create this surcharge. claiming to lose vast sums of money from people who At one point I thought a surcharge would be a tape friend's records. good way to make sure that artists didn't get ripped Who's right in all this? Who's wrong? Well, off. But now I'm not so sure. neither side is completely without blame. For example, what about all the people who use First things first: If you like a record your cassettes for data storage in' computers? Will they friend has, and tape it for your own use, you are have to pay? What about the people who record their violating the law by committing theft - it's like own music and send out cassettes to friends - will shoplifting, where you enjoy the use of a product they have to pay a surcharge on cassettes over which but never pay for it. Some people are aware they're they will record their own music? What about cas­ doing something incorrect, and justify their actions settes used in answering or dictation machines...or by saying that "records are so expensive nowadays". motivational cassettes, religious cassettes, demo That's true - but cars are expensive nowadays as cassettes, and cassette letters? well. Does that mean it's all right to steal a car Admittedly I'm not your average audiophile if you can't afford one? consumer, but of the last eighty cassettes I've On the other hand, if you've bought a record bought, two taped someone else's pre-recorded music, and want to make a tape of it for your car, it seems while the other seventy-eight either were used for to me (I'm no lawyer, of course) that by buying the making copies of my own music, or for making "great­ record, you've brought the rights to listen to that est hits" tapes and car tapes from my record collec­ piece of music as many times as you like. If that tion. Oh, and before you say "see, he tapes stuff involves taping the music for your own private use, too", let me add that of those two records one was I don't see any problem. Besides, many pre-recorded out of print, and the other was impossible to find tapes are of dubious quality, so the careful home where I live. taper is going to be able to make a higher quality I know there are plenty of people out there who dub. buy cassettes strictly to tape their friend's It would be convenient if the record companies records, but I_ also know there are plenty of people were easily identifiable "good guys" in this matter. out there who have legitimate uses for cassettes But, the fact that a majority of albums (I've heard which do not involve any kind of dishonesty. The over 75%) fail to recoup their investment means that proposed surcharge would penalize these people - the the labels are definitely doing something wrong; so people who have done nothing wrong - as well as far, the answer has been to increase prices (not the those who blithely ignore the copyright laws. best of all possible solutions for a slumping indus­ What about a technological fix, such as putting try). And record companies have certainly been a supersonic tone on the disc which drives the bias known to rip off the consumer - with warped records, oscillator of the tape deck crazy? Possible, per­ terrible quality vinyl, repackaged greatest hits haps, but then someone will just market a filter to albums with one previously-unreleased single to snag get rid of it. I don't think a technological fix is all the "collectors" in the crowd - and to rip off the answer, because any electronic lock can be their own artists as well. Sure, they're crying the picked...just ask the computer software or pay-TV blues; home taping is a convenient scapegoat. How­ people. ever, the true root of the problem has more facets I'm hoping some Polyphony reader can come up than the record industry would care to admit, and with a simple, elegant, workable and above all FAIR involves more than just home taping. solution to the problem of home taping. Something Let me emphasize right now that I don't have which makes sure that people are justly compensated any solution to the problem. If all people were for the fruits of their work. Something which idealists who strived for honesty, we wouldn't have doesn't penalize the honest user. any problem...but I don't think the human race is The fundamental question goes much deeper, going to change overnight. So, we need some kind of though, and touches on much more than cassettes. We solution which will penalize those who are dishon­ create technologies which can save lives, take est, not penalize those who are honest, and make lives, make music, or steal music. The machines sure that people get paid what's due them for their have no sense of right or wrong - that's up to us. work. Granted, some rock musician may be making We have the intelligence to make incredible devices; millions and you might think he or she won't miss all we need now is the wisdom to use them correctly. the extra buck - but what about the 10 years of living on spaghetti and peanut butter sandwiches? Musicians (and yes, record companies too) pay their dues, and deserve to be paid for doing what they do. Some people think they have a solution, which is to add a surcharge to recording tape and certain Craig Anderton

4 POUPHONU M ay - August 1982 KB S # m Immamm

ATTENTION TAPE MAKERS! know one another. singer than instrumentalist, but The review service would also I'm uncomfortable with "scat" In Robert Carlberg's Review provide direct feedback; if the singing. Is there a box which column in the Sept/Oct 1981 issue, artist encloses a self-addressed, will follow my vocal line, pitch he restricted his reviews to tapes stamped envelope, I'll send a and amplitude wise, but produce with national distribution. Be­ detailed critique by mail if de­ the sound of a trumpet or sax (or cause I do not have my material sired. Also include your phone organ cr zither, for that matter)? handled by a national distributor, number so that I have the option My second question concerns I feel that I have been eliminated to give a phone critique. the Casio 202 keyboard I own. from an important phase of our Sound interesting? Here's I've seen articles on modifying craft: feedback. I shall not put how the service works. Casio's less expensive toys, but a hex on any of the national dis­ 1. We operate on a first in, nothing on making the 202 more tributors, for they provide a first out basis. useful. Is there a way to repro­ necessary function. I, however, 2. The number of listings gram some of the canned voices? am not yet ready for them. I also published will depend on the space Are they stored on ROMs, which feel that I am not alone in this available in Polyphony. could be replaced with other ROMs, respect. For each and every Don 3. Each listing will appear programmed for more interesting, Slepian (whom I consider to be a only once. realistic sounds? Although there real master) there exists at least 4. Tapes will only be re­ are 44 different voices, lots of a hundred of us who are still turned if you include return post­ them are either useless or redun­ trying to "make it". Our talents age. dant. If we could work out a way range from "squeeks and whistles" 5. To receive telephone con­ to make this inexpensive axe more to some "good complex music". If firmation and brief critique, you versatile, we'd have a world beat­ we must compete with the Slepians must include your DAYTIME phone er . of the craft for review space, number. Calls are restricted to there is no question who wins. the continental United States. George Western It may seem at this point 6. To receive a detailed Clovis, CA that I am suggesting that Mr. critique, include a self-addressed Carlberg "clean up his act". This stamped envelope. George - What you want is is not true - Mr. Carlberg pro­ 7. We will not distribute something like the Gentle Electric duces an excellent column. This your material. Selling your stuff Pitch to Voltage converter, which does, however, bring me to my is your business, not ours. provides pitch and amplitude ex­ point. The Pros should be re­ So...if you're interested, traction from a signal. Roland viewed by the Pro (currently being mail your material to: also makes a pitch-to-voltage con­ done by Mr. Carlberg), and the verter as part of their Roland Novices should be reviewed by some Marvin Peterson Rack series. While these devices other means. With this concept in Dragonbreath Music Systems are often used with guitar, you'll mind, I'm making the following 34 Winchester Drive find the performance is much less proposal to Polyphony and to the Wakefield, RI 02879 critical with voice, which has a many Novices who avidly read it. simpler waveform. I would like to provide a Marvin - This sounds like a In the meantime, try putting review service, with the results good way for those just getting your voice through a fuzz to con­ published in a simple one or two into home recording to hear some vert it into something with lots line format, and including a star valuable feedback on their work. of harmonics, follow that with a rating (similar to many of the What do you think, readers? If footpedal so that you can alter movie reviews published in local you'd like to see this becomes a the dynamics, and follow the pedal newspapers). The format would regular feature in Polyphony, send with a flanger, phaser, envelope include only the basic information your tapes to Marvin. If the followed filter, or whatever. such as name, type of material, response is sufficient, we'll go You'll probably be limited to address, purchase price, and a one with it. kazoo type sounds at first, but to five star rating. This format eventually, you'll get to the would allow the maximum quantity SING ALONG WITH... point where you'll have some m u ­ of artists to be covered in the sically valid effects. minimum amount of space. This I was hoping you'd be able to As far as the Casio 202 is type of format will also make help with my search for a device concerned...what about it, read­ available a large list of names of which would enable me to "play" my ers? Any good mods floating people who might want to get to solo lines vocally. I am a better around out there? Let us know. • POUPHONy- — May - August 1982 5 Applied Synthesis:

HARPSICHORD ELECTRONIC PIANO PIPE ORGAN BELLS

By: Bill Rhodes

In this installment of applied synthesis, we might want to duplicate the pop and click of the will approach the electronic keyboard as a pseudo string by adjusting your resonance control. "acoustic" keyboard instrument. As everyone knows, • Execution: Practice your Bach 2 Part Inven­ acoustic piano is probably one of the most difficult tions and clavichord pieces (i.e. French Suites and instruments to fully capture synthetically. Sax, Goldberg Variations). They will help with the arti­ voices, and guitar follow close behind, but piano is culation you will need in harpsichord performance. a stickler. The various overtone series, harmonics Listen to harpsichord players such as Anthony New­ and their anomalies, the shift of waveform according man, Rick Wakeman (a different genre), and the mas­ to registration, the velocity and/or tactile ters. Remember, the fingers act like tiny pistons sensitivity, and attack (filter and volume) of the driving down the keys, so the execution of the instrument are the criteria recognized for passages must be articulate and intentional. synthesis. In a future issue of Polyphony, we will deal with acoustic piano imitation in depth; in this Bells. For bell-like keyboard synthesis, try issue, we will deal with the electronic piano (e.g. the following: Fender Rhodes), harpsichord, pipe organ and bell • Registration: Keep oscillators tuned to sounds. unison at the same octave. Harpsichord. One of the best sounding synthe­ • Waveform: Use the triangle or square with tic imitations is the harpsichord. Some of the filter settings that are more rounded than harsh. various poly-synths out on the market (Korg Polysix Bells and bell-like instruments have fewer harmonics B7 program, OBX-SA, Moog Poly, Yamaha electric than brass or string instruments; however, chimes pianos, Roland electric piano, Prophet 5, and numer­ are a complex arrangement of many waveforms, regis­ ous others) have great sounding preset harpsichords. trations, and ring modulations (the sum and differ­ But to duplicate from scratch, let us look at the ence of two frequencies). most important parameters. • Envelope: Instant attack, sharp decay, • Registration: Octave and combination of lingering sustain, and long release are basic char­ octave voices is very important to give the depth acteristics of bells. A slight triangle or sine and punch we need. Combine a 16 foot and 8 foot wave modulation at a slow rate is very interesting oscillator in exact (if possible, use sync) tuning with this combination - so experiment. Because to create the proper sound. bells are usually struck by a hard mallet, try to • Waveform: Harpsichords are rather buzzy and imitate the attack characteristic by adjusting fil­ tinny sounding in the upper registration. Select a ter and VCA decay to approximate a percussive hit. combination of sawtooth and pulse waveforms in both Be careful not to overuse these sounds (unless you the 8 foot and 16 foot registrations. Don't bother write a bell and orchestra concerto!), but use them with triangle waveforms because they don't have the effectively in your performance. harmonic content of odd footages we need for the harpsichord. • Envelope: Instantaneous attack (VCF and Pipe organ. The following approximate the VCA), relatively short decay, full sustain, and sound of a pipe organ with all stops pulled. slightly reverberant (depending on the virtuosity or • Registration: Combine 2 foot, 4 foot, 8 velocity of the passage) release is needed for the foot, 16 foot, 32 foot, Big Foot, etc. to obtain the harpsisound. Punchiness of attack in the VCF is thunderous quality of a Bach Toccata. The footages very important; the low end punch should be felt as we use today were derived from the lengths of a pipe well as heard if you crank up your amplifier. organ pipe. The pipe organ used a myriad footage • Filter: Use a high pass filter and low pass combinations for both manuals as well as the foot filter in combination if you can. The high pass pedals. will give you the sibilance (brightness and "nasali­ • Waveform: Use square waves in different ty" if you will) and the low pass, the balls. A footage combinations to become more complex "saw­ variety of synthesizers sound too phony because the tooth" sonorities. Tune each oscillator almost to filter is too reedy or too bassy. Also, since a unison. Remember, the pipes and flues of the organ harpsichord string is plucked with a plectrum (pick) are never exactly in tune. You may want to demodu­ rather than hit with a hammer like a piano, you late or de-chorus the entire tuning. The old Arp

6 POUPHONU------M ay - August 1982 string unit (Solina) had this feature, as do some (AM). This can be realized by twisting a volume Korg instruments (called "ensemble defeat"). control back and forth while holding down a note on • Envelope: No attack, no decay, full sustain the keyboard. In the Rhodes, the circuit which - but you may want to lengthen the release somewhat creates the shifting of sound between speakers is for a more reverberant sound. called the tremolo circuit. Square wave modulation • Filter: Low pass filter set at a very set at the proper depth on the LFO circuit will bright, "non-wow" (keep resonance tone low) posi­ duplicate the on-off effect. tion. The full pipe sound is very loud and bright. A neat trick to create an echo effect with • Execution: Listen to Wakeman's "Six Wives varying repeats is using the square wave modulation. of Henry VIII", Keith Emerson's "The Three Fates" Get the desired on-off effect which is in tune with (first ELP album), E. Power Biggs and Virgil Fox's itself (meaning that the LFO is "synched" with the interpretation of Bach's "Toccata and Fugue in D audio oscillator and not changing the pitch) and add minor", etc. Try to get access to a real pipe organ some VCA release. The Crumar Orchestrator brass can so that you can experiment with the various stops be echoed by increasing the sustain fader and play­ and footages. Drag your synth into church with you ing very articulately on the keys. You will experi­ and try to duplicate the sounds (God and preacher ence an interesting echoed brass effect if you mix willing). the strings slightly with the polyphonic instrument. For a mellow, flute like pipe organ sound, use In this installment, I've touched on the basic the same envelope as above, change registration to keyboard instrument sounds which we all use. Ac­ one footage (4' or 8'), lower filter setting to cording to your synth and sound reinforcement sys­ "mellow", change waveform to square or triangle tem, certain parameters may have to be varied to a only, lighten up on volume, try to establish a different degree of intensity. Please experiment "breathing" type effect (use a slight bit of white and realize you have a good foundation to start noise). Use a sound like a recorder, but put it to creating the sounds you need. polyphonic use. Just think, by imitating keyboards with your synth, consider the weight you won't have to carry Rhodes-like sound. We won't attempt to dupli­ around: all those pianos, pipes, wind chests, mal­ cate the pianistic qualities (the mechanical and lets, bars, effects boxes, road cases, candelabra, dynamic nuances) of this instrument exactly, but try tuning hammers, pedals, Rhodes piano legs, covers, a good approximation. Use the envelope of a piano- etc. etc... type instrument, that being instantaneous attack, sharp filter decay, slightly less than full VCA Next time around, we cover synthetic choir sustain and release depending on the passage you are voices. Stay tuned, everfriends. playing. If you have provisions for a damper con­ trol pedal (such as the Korg Trident), use it like a piano's sustain pedal. The waveform for a Rhodes- type sound would be in the bellish square wave category. A Rhodes has a characteristic bell-like timbre if equalized with a high top end. On some Rhodes set-ups, you can hear the sound of the "hammer" striking the key tine. Vary the filter resonance control on the filter to simulate this pop or click sound. • Effects: That rolling stereo "vibrato" sound we all like and recognize on the Rhodes can be duplicated by the modulation circuit on your synth. With the LFO modulating the VCO with a sine or triangle wave (set at a slow rate and shallow depth) you can to some degree imitate that "tremulated" effect. Please note there is a distinct difference, though, between vibrato and tremolo, so let's clear up any confusion: Vibrato is frequency modulation (FM) or a dynamic change in pitch. With rotating speaker organ cabinets, the full effect created by the spinning rotors and horns results from a change in pitch, not volume. The change in pitch is a Doppler effect created by the sounds being thrown out of the cabinet and moving around the room. A good analogy of the Doppler phenomenon is this: A car approaches as you stand by the side of the road. In order not to hit you and cause bodily injury, the driver blows his horn at you. As he passes you while sustaining his volume with the horn, you will hear a dramatic change in pitch. The ear perceives one pitch or pitches before he passes you and then hears another pitch after he passes you; hence, a modulation of the basic pitch or frequency. Tremolo is simply an on-off alteration of sound. This is called amplitude (volume) modulation

POUPHONy M a y - August 1982 7 Anatomy of a Private Record

n — by Robert Carlberg

Craig Anderton's comments in possible were all highly recom­ independent releases number in the the November/December issue re­ mended. As Leon Lowman put it, hundreds. With addresses, the garding independent releases got "You'd better be a go-getter or list would take up too much space me thinking. Do all independent you might as well forget it!" to print here. Perhaps if there releases break even? Is there a There were some distributors is sufficient interest, Polyphony network of distributors available? who were frequently mentioned, but could devote a couple pages in the Does the artistic freedom outweigh the message in the questionnaires near future to listing them. the financial gamble? was that no record will sell it­ Write Polyphony if you think this To answer these and other self. The distributors mainly do information would be useful to questions, I distributed a ques­ that - distribute the record to you. (Here's my vote! - Editor) tionnaire to a number of artists interested buyers. Getting the Besides Polyphony, the other who had recently released private potential buyers interested is publications which have yielded electronic music albums. Their your job. advertising results for private responses provided verification The distributors most often releases are: for most of Craig's comments, with mentioned were: plenty of warm encouragement and a Keyboard magazine few small surprises. 20605 Lanzaneo First and foremost, almost New Music Distribution Service Cupertino, CA 95014 all respondents recommended pri­ Division J. C. 0. A. vate releases as a good way to get 500 Broadway Eurock magazine your name around. Nearly everyone New York, NY 10012 PO Box 4181 broke even on the deal and a few Torrance, CA 90510 even made money. However, in the Aeon Import Records words of Marc Barreca, "If strict­ 604 Princeton OP (division of Lost Music ly commercial success is looked Fort Collins, CO 80525 Network) for, a private release should be PO Box 2391 mainly for promo". Or again, from Greenworld Records, Ltd. Olympia, WA 98507 Jasun Martz, "The goal of an inde­ 23703 Madison St. pendent release should be artis­ Torrance, CA 90505 Advertising outside of the tic. It seems very few 'indies' electronic/experimental periodi­ make money and thus the project Square Deal Records cals is very iffy, according to a should not be undertaken with San Luis Obispo, CA couple of respondents, since your (making money) in mind". chances of reaching the right The artists who made a pro­ Systematic Record Distribution person do not necessarily go up fit with their records are the Berkeley Industrial Court, with larger-circulation magazines ones who worked hardest to sell Space 1 - but your advertising costs most them. For independents especial­ 729 Heinz Avenue certainly do. Cost consciousness ly, writing, recording, and making Berkeley, CA 94710 is essential to the financial the record is only the beginning. success of an independent release. From there on, the artist must Most of the problems people As a matter of fact, this is promote him or herself tirelessly. had with distributors was cash one area where the electronic The independent market is, accord­ flow. With the possible exception musician has a huge advantage over ing to Gilbert Trythall, "the of the N. M. D. S., all of these almost any other musician. Be­ equivalent of the small specialty distributors are shoestring opera­ cause a home recording studio is press, and the largest problem is tions, and they are not in a posi­ almost a prerequisite for the reaching people who are interested tion to pay in advance for large electronic musician, he or she can in what you're doing". Taking out shipments. But patience and per- afford to spend whatever time is ads in publications which special­ severence pay off, and the artists necessary to perfect the record­ ize in electronic music, sending almost always got paid eventually. ing. The questionnaire answers promo copies and letters (or bet­ There were one or two other dis­ ranged from 60 hours to over a ter yet, visiting) radio stations tributors who reportedly "regular­ year in the studio, which would be who play progressive music, and ly ripped-off independents", how­ extremely expensive under commer­ contacting as many distributors ever, so caution is the byword. cial studio rates. Many commer­ who handle independent releases as The radio stations which play cial recording studios offer pack-

8 POUPHONU May - August 1982 aged deals where a vocalist can Alright, everyone loves the long time to come. come in and sing over pre-recorded tape. How do you get it on to From there, you simply sign backing tracks for a set fee. vinyl? The first step is to off the test pressings and you're Luckily, electronic music has not choose a record presser. There underway. You will shortly have a been limited by such cost restric­ are numerous choices, but three basement full of assets to get rid tions, and the result is that most names kept coming up in the ques­ of. Since all of this pressing independent releases rival, if not tionnaires. All three are highly business is cash-in-advance (or improve on, the major studio pro­ regarded by those who used them, half-on-delivery), the return on ductions . so geographical nearness is pro­ your investment will be staring Certainly, the freedom to bably the determining factor: you in the face every time you do "get it right" is important to laundry (or whatever it is you do independents. "The best thing QCA Custom Pressing, Inc. in the basement). If that isn't about doing it yourself", says our 2832 Spring Grove Avenue motivation enough to get out and own Craig Anderton, "is that you Cincinnati, OH 45225 sell a few records, nothing is. make the music you want to make. Does the artistic freedom You never have the situation where Wakefield Manufacturing, Inc. outweigh the artistic gamble? I you have to compromise, the album PO Box 6037 can only report that every ques­ flops, and you wonder, '...if only Phoenix, AZ 85005 tionnaire says yes on this point. I'd insisted on doing it my way, Perhaps Leon Lowman summed it up maybe it would have sold.' Con­ Location Recording Service, Inc. best: "Putting out your own re­ versely, if the album does well, 2201 West Burbank Blvd. cord is not for the lazy, not for you can pat yourself on the back Burbank, CA 91506 the timid - you gotta work. But without any doubts." Self-expres­ if you don't try it how will you sion should be your motivation, Beware of "bargain" deals - ever find out where you stand in says Don Slepian, "and you will they usually end up costing more the world of music? Go for it!" allow no person or obstacle to than expected. These pressing stand between you and your self- plants may charge a bit more ini­ expression" . tially, but everyone agrees they So let's say you've got your are still the least expensive A NEW LOOK FOR master tape all finished - what's overall. next? Don Slepian offers some The next step is to have your very sound advice: "Gain access tape mastered, which means a pro­ P b fy p h o r$ ) to a high quality cassette record­ fessional, usually associated with er and make 20 copies of your the pressing plant, sets the dyna­ prospective master tape, then sell mic range, the timings, and the COMING IN OCTOBER all 20 copies.- If you can't sell equalization so that your music all 20 copies (and not to dear will translate on to vinyl in the GIL TRYTHALL'S friends), then you should re­ best possible way. This is no LUXIKON II / ECHOSPACE examine your master tape before easy feat, and no compromises pressing it into a record". Lis­ should be allowed. The masterer MULTI-TEXTURED AND UNIQUL. " ten to the advice offered to you will provide you with an acetate, Robert (arlhurg in POL YPHONY by the buyers of your tapes (and a wax-like pressing for you to IJGHTNING QUICK KEY BOARD IMPROVISATIONS" everyone's a critic when you ask evaluate. Three or four tries James E. Einch in SYNE "SYNTHESISE TO KELP AN EAR OUT TOR. " them). Remember, a total stranger before you're both satisfied is /.on Vern Pyles in SYNEX may not appreciate your rendition not unusual, since the mastering "REALLY BEAUTIIUL SEGMENTS" of Klaus Schulze's "Moondawn" if technician probably has never Jim Aik in in CONTEMPORAR Y KEYBOARD he or she has never heard "Moon- heard music like yours before, and dawn". The stranger also might you've never mastered a record NOW Gil's "SWITCHED ON NASHVILLE" not wish to sit through 22 minutes before. But if you choose care­ is back! Twelve fully synthesized classics. of intense jamming if you had to fully, the technician will be a be there to appreciate it. Make professional with good advice and .rauiHTnv inaaG the record you want to make, but an honest desire to please your I. lM 'n ,l i. bear in mind that you still have ear. to sell it. Next you have a test pressing Some advice from respondents made. This is your first oppor­ about the cover: If you're not an tunity to hear yourself on a "real artist (or strangers think you're record", a thrill that never seems not), find someone who is to help to wear off. Assuming the final you out. The cover is the first check (changes here cause a new impression anyone gets of your mastering charge!) comes out okay, album, and if you make it as far you're ready to press. You're "HIGHLY RECOMMENDED" as the record store, the only basically checking the quality of Tom Rhea in CONTEMPORARY KEYBOARD impression. Don Slepian, whose the vinyl, the trackability of the record is very professional except lathing, and the final check of LUXIKON II / ECHOSPACE $7.95 postpaid for a cover which is a bit silly, the EQ, stereo balance, and dy­ COUNTRY MOOG $7.95 postpaid admits "Next time I would spend namics. Don't be afraid to make BOTH ALBUMS FOR ONLY $12.96 postpaid. more time and care in packaging. changes if you aren't happy - PANDORA Next time I wouldn't be so naive." you'll have to live with it for a P. 0 . BOX 2281 WESTOVER, WV 26505

POUPHONU M ay - August 1982 9 DON SLEP1AN Don Slepian is a familiar name to many Poly­ outside surroundings to be conducive to a musical phony readers. His self-produced, imaginative cas­ state of consciousness, because I really do not sit settes and records have earned excellent reviews and plan exactly what is going to happen on tape. from those critics interested in non-mainstream Improvisation has been the way I've worked for 20 music. years...it has always been my path. The following interview is excerpted from a I'll entirely improvise the first layer, and do lengthier interview conducted by Don Schwartz, and far more than I need. Usually another day or two focusses specifically on Don Slepian's compositional will pass, and then I will come back and do exten­ techniques. But don't think you have to be a pro­ sive tape editing and tape manipulation. I'll have, fessional musician to get something out of this say, an hour of music which has been improvised, and interview - Don has something to say to the frus­ I will take that and cut it down into maybe half an trated music maker and amateur as well. hour of the best parts, in a way that they flow By the way, "D" refers to Don Schwartz, while imperceptibly, one into another. The most important "DS" refers to Don Slepian. tool in my whole craft has been the razor blade and tape splicer. I have put a lot of time and care into developing the art of splicing, and of editing. That's the editing process for me; next is to D: I want to begin the interview by saying that I learn the improvisation I've done on the first layer love your music. Can you talk a bit about your to prepare for recording the nd and rd layers. composing process, because I hear a very thoughtful 2 3 These subsequent layers respond to what is consideration in your work. The many layers and already on tape. I'm still free; in other words, I levels sound as if you have spent hours upon hours still simply give myself the sonic materials, and choosing how to integrate these sounds you make. create in response to what I hear. However, on the second and third layers I will stop myself, go back, DS: One representative piece, the Sea of Bliss, has and maintain a certain standard of exactly what I three levels to it and is made in three layers. want. It's a different sort of process to do over­ Most of my work is done on a four-channel tape dubs than it is to create the original source of the recorder, or less. I start out first from a techni­ music. The first track is the foundation, and that cal aspect. I get a repertoire of sounds which I only gets edited and put together - if it's worthy, feel are going to work for me, and once I've found and a firm foundation, I'll proceed to the next those sounds, then I think of an idea or concept. layers. Once I have both the technical end and the concept, then I enter an area of improvisation, in "Improvization, ,*..## has always which, say, I'll have a clock, and a beginning time, and an ending time, and I'll adjust the lights and been my path ” 10 POUPHCNy------M ay - August 1982 D: You said earlier that you get a "concept". Can in a very specialized way. I certainly do work. My you talk about that? two years in the music business of producing cas­ settes and the like have yet to bring in a total of DS: 360 degrees of freedom is overwhelming in mu­ one month's rent. As far as income, it actually has sic, and you need not truly begin to find freedom been quite a loss. So, I teach one day a week at until you put yourself under extremely narrow con­ Fairleigh Dickinson University, which is a private straints - particularly in the composition process. university close to me. I teach electronic music You want to look at one small area, and develop and a lot of private piano ins true t ion...teaching within that area. people Bruce Springsteen songs, Tom Petty, whatever For example, there are two pieces of mine - they want to learn. I enjoy teaching, learning, and "Sea of Bliss" and "Awakening" - in which I look at playing the instrument; one of my strongest back­ developing long notes, far longer notes than are grounds is in classical piano. common in Western music. I was coming from the eight second melody notes used in gamelan music in D: You're classically trained? the Javanese tradition, since I was a member of the Gamelan for a year and was influenced by that. DS: Yes. I also do a great deal of custom elec­ There, in the slow gamelan, the saron melody can be tronic work for a clientele that often includes New as long as eight seconds for each note. I was York studio musicians. I'm mostly involved in modi- working with a synthetic tone, which can swell up fying commercially devices or building devices which like a violin, and then have a very long sustain, are not available commercially. That's an interest­ with one note blending into the other. So in that ing craft. I've always been involved with elec­ case, the concept was an unusual type of note, an tronics and I've always had this duality of elec­ unusual sound. tronics and music. I have had both interests, and of course I have had to do a great deal of custom "The most important tool in my work on my own equipment in order to be able to produce the sounds I want. On an extremely limited whole craft has been the razor blade budget, I have had to become quite adept at modi­ and tape splicer. ” fying and expanding synthesizers and tape recording equipment. A concept can be first of all a technical concept, such as a certain type of permutation or D: So what you're doing with teaching and working different computer algorithm, or it can be an aes­ on instruments feeds into your compositional re­ thetic concept, such as working with tape-trans­ cording work. formed acoustical instruments and having a certain thing to say. No matter what the concept really is, DS: I'm not so sure about the teaching. I'm doing just the idea of narrowing your scope is important, it now, but if things pick up, then I will probably so that what you are doing has some focus. take some time away from teaching. Electronics and music go together quite well, and I just have to D: What kinds of music would you like to explore? balance those sides of what I do. I do so much Where do you see yourself heading? electronics I get frustrated, and I want to be able to put down my soldering iron and do the music. DS: Well, it's not so much types of music, it's effects or emotions. I’m interested in working with "Electronics and music go together some more challenging types of feelings than simply that of blissfulness and serenity. There are other quite well ....I just have to balance emotions out there which are equally powerful, such as sadness, tragedy, elation. I think of the bar­ what Ido.... I want to be able to oque composers in the doctrine of the twenty af­ put down my soltiering iron and do fects, back a few hundred years ago; they had cata­ logued certain emotions, and the composers were the music.” trained by being able to actually produce those emotions in people, to share them, to elicit back reactions from an audience without lyric, with music D: Do you have any interest in video composition? only. That’s what I'm looking for in a direction - to take abstract sound, and find those elements DS: I' m interested in analog video synthesis, which which will touch upon the feelings of people, and in - at its most mundane level - looks somewhat like doing that, I would produce an emotional catharsis, electronic wallpaper. Whereas I do music which or some uplifting of the spirit. evokes emotion and yet is without language, I am interested in doing television visual images, on a "...J have had to become quite more abstract level, without the concreteness of consistently recognizable objects, without keying adept at modifying and expanding people into saying "this is a chair", or "this is a synthesizers and tape recording human face". And yet, visually, I have the same sort of compositional goals as I do with the music. equipment." In other words, I am looking for communication to link directly with the feelings, emotions, and D: What do you do in addition to recording and thoughts of people. I want to do that with as releasing tapes? little cultural definition as possible. I'm very interested in reaching out to the DS: At this point, I haven't been performing for people of South America, Africa, China...an enormous some time, although I'd like to get back into that quantity of people have been completely ignored by, ro u rH Q N y------M ay - August 1982 -\-\ say, certainly the art I'm in, and a great deal of Of course, you also have to judge that inspira­ Western music and art. There are huge areas of the tion; a composer has to be his or her most stringent planet which have been ignored because it's diffi­ critic. Striking a balance between the critic and cult, if not impossible, to commercially exploit composer impulses is the key: years went by without them. One of the keys to reaching these people is me producing a thing because the critic impulse was to move away from the constrictions of the English too strong - that is, you edit and edit until you language, the straight-jacket of my language, my end up with about an inch of tape! There has to be thinking, of my conceptualization. a certain letting go, a certain willingness to be I see this idea of music without words, and wrong. I hear the mistakes and errors in my mu­ television without concrete images, as a sort of sic...! hear the things that aren't right. And, ideal symbiosis - they can feed upon each other. it's essential, as part of that balance, to look Well, maybe that's not saying it quite right, let's overall at a piece of music and say, "the music in just say it's an ideal symbiosis of two forms which it is here...is worthy...considered as a whole. It will support each other. is okay with me to let this out". There's always the tension between excitation 111 record as much as possible and inhibition. For instance, in playing classical piano, much of classical performance is balanced at hom e" between these two forces - if there is no excita­ tion, the pianist sits there and looks at the key­ D: I'm interested in the recording aspect of your board and plays nothing. If there is no inhibition, music, particularly your recording at home. the pianist starts the piece at double tempo, plays like a maniac, and often ends up on the floor in a DS: I record as much as possible at home. There tangle! In music composition, you must first have are times when I will record at home and then take the inspiration and then, from the inspiration, you these tracks to a recording studio, transfer them to have the craft, the tools, the technique, the train­ a multi-track, and overdub additional parts. Or ing, the aesthetic maturity, to be able to look over there are times when I will record things on loca­ your inspiration and create something focussed. tion and then bring them back home and transfer them to what I have at home. For me, a large part of it D: Here's a question...how can somebody find your has been getting the most I can out of four-channel, music? and doing the best job I can with hi-fi and semi-pro equipment. I consider myself very fortunate to have DS: Well, one way is to write me at PO Box 836, a four-channel, and to have the tools that I do use, Edison, NJ 08818; Don and Judy Records - our com­ and I see over and over again that you can make a pany - will always carry and service our music to at great deal of use out of what is at hand. Before I least some small degree. The other sources are had a four-channel I had a two-channel, and I was Ethan Edgecombe, Fortuna Records, PO Box 1116, Nova­ able to make a great deal of music with that. to, CA 94947, which services the San Francisco Bay With the music that I'm doing right now, it's Area; Plumeria Productions Hawaii, PO Box 54, becoming more and more necessary to get more of the Kailua, HI 96734; and Eurock Mailorder, PO Box tools that are in the mainstream of recording art, 4181, Torrance, CA 90510, who sells the music all such as an 8 or 16 track tape recorder, a synchroni­ around the world. zer between that and my video tape recorder, and other such things. As far as recording, I don't have any unique “I see too many people playing philosophy or even particularly unique style. I records and not enough people guess the only thing that I do now is use very little equalization. Whenever possible, I put playing instruments,** exactly the sound I want on the master tape, and I believe in passing through the minimum amount of electronics in order to get the sound. And I have D: Is there anything that you want to say in the no regard for standards, other than results - if I way of a conclusion? hear good musical results from tape saturation or non-linear distortion, I'll use it. I will not DS: This may be contradictory, but I enjoy live fight the equipment in my studio, I work harmonious­ music far more than I enjoy anything coming from a ly with it. It's virtually an unconscious process loudspeaker. I seek out concerts of live musicians. because when I do create my music, I am not in a I'm concerned about recorded music taking over for normal state of consciousness. I'll often do an some people, or for many people, the role that live hour of taping, in isolation, late at night; then music has played. I believe that everybody has I'll listen back to see what I've done. musical ability, and that we are all musicians. A large part of my work is preparing myself and And, I see a tremendous decline in the number of the tools of my craft to be the proper recipient for amateur musicians - the number of people who will inspiration. The technical skills that I polish, my pick up an instrument - compared to the number of work on all my instruments, my electronic work, people who will put a cassette in the machine or a everything that I do would be useless, would be record on the record player. I see too many people totally meaningless if, at that moment when the red playing records and not enough people playing ins­ light is on the tape recorder and the reels are truments. I think if one were to look for music, spinning, the inspiration is not there. All that I your first choice would be to pick up an instrument do is preparation for that moment...in that respect, and play it yourself; and, if that weren't right for although it's a cliche, I really do think of myself you, your second choice would be to find a musician as more of a channel for the music than anything next door or down the street, and listen to him or else. her; the third choice would be loudspeaker music. 12 POLUPHONU ------May - August 1982 D: That's certainly provocative, considering that some of the greatest minds of the century are at work creating the best possible reproduction systems MANUFACTURER’S CLOSE-OUT SALE to reproduce live music as accurately as possible. Huge savings on prime parts! CD4007UBE CMOS Transistor Array $4.95/25 DS: That's true. The loudspeaker music is CD4016BE Quad Analog Sw. $4.95/20 excellent, I don't doubt that...I'm just saying CD4041BE Quad Complementary Buffer $$11.95/25 (for driving BBD's) there's a spiritual aspect of music that is lost CD4046BE CMOS PLLi $17.25/25 without the presence of the musician, and that CD4047BE CMOS ASTABLE/OSC. $13.95/25 CD4049AE Hex Inverter $4.75/25 quality is lost when music is reproduced rather than CD4040BE 14 Stage Ripple Counter $8.75/25 created at the moment. Because, in the presence of SCL4416BE Like 4016 but 2 switches $8.75/25 the creation of music, it is a different experience are N.C. (for DPDT Sw.) than to be present at the recreation of music. I MC1458N Dual OP AMP 8-pin DIP $14.50/50 TL044CN Quad Low Power OP AMP $15.95/20 hope people wouldn't hear ray music and say "I could 16-pin DIP never do that", and feel discouraged from playing LM78L15 15V Reg. lOOma TO-92 $3.95/10 the music themselves. LM78M15 15V Reg. 500ma TO-220 $4.95/10 TL4 87 5-step LOG LED Meter $9.95/10 8-pin DIP D: It sounds as if you would like to inspire them MN3005 BBD 4096-Stage 8-pin DIP $75/4 to play from your music. MN3010 BBD Dual 512-Stage $49/6 14-pin DIP MN3011 BBD 3385-Stage w/6 Taps $39/2 DS: I want them to pick up the instrument. I would (Reverb) like to see a resurgence of amateur musicians. I SAD-1024 BBD Dual 512-Stage $36/5 would like to see more people play piano, guitar, 16-pin DIP 2N4393 N-Channel FET $12/100 flute, whatever instrument is right for them. 2N3369 N-Channel FET $15/100 2N5830 NPN $10/100 D: I agree totally. I think a lot of the problems 14-pin Socket AMP Low Profile $12/100 of our times come from people being passive reci­ 16-pin Socket AUGAT Low Profile $13/100 18-pin Socket AMP Low Profile $1.75/12 pients of life rather than active participants and L.E.D. Red .118"(3mm)Dia. Diffused $10/100 creators. L.E.D. Green .118"(3mm)Dia. Diffused $10/100 A L.E.D. Red Triangular .200" $10/100 3-wire AC Line Cord SPT-2 Type $6.95/10 DS: You put your finger on it! Everyone has a need B Switchcraft Stereo Cord, 18" V-Phone Plugs $39/20 for self-expression, that's part of health. And C Switchcraft 712A COAX Power Jack $2.49/5 what I see so little of is people picking up the Pin I.D. =.100" D POT(Japan) 17mm w/6mm Knurled Shaft 50K $17.50/50 paint brush or the pencil to write. I want to Linear PC Mount, Washer Nut Incl. encourage people to do what I do...I want to say E Transformer PRI:115VAC SEC:DUAL 10V $39.95/6 that, in certain ways, who I am and what I do is 250ma PC Mount nothing special, that everybody out there can be a F Transformer PRI:115/220VAC SEC:20V $29.95/6 45ma PC Mount (very small) channel if they are open to it. Everyone has a G Transformer PRI:115VAC SEC:40V 300ma $34.95/6 creative force they can use, and everyone can Wire Leads w/Channel Mount create. And, I'd just like to see people find a H Fuse Holder Chassis Mount, Solder Lug $3.95/10 medium for creation and express themselves at what­ 15mm Hole Size J Trimpots 10mm Type 50K, 100K, 20K $5/50 ever level. That's all the conclusion I have.

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POUPHONU M a y - August 1982 13 the receiver, is powered by a 9V battery and comes The Phase Checker with cannon, phone, and phono jacks. The receiver has an internal electret micro­ phone to test acoustic transducers (speakers etc.), A Review or you can feed a 10 mV to 10V signal into the mic input, or a IV to 100V signal into the line input. By: Craig Anderton You use the combination by feeding the trans­ mitter into the device under test, and feeding the Every now and then you run across a useful output from the device into the receiver. A light piece of equipment that ingeniously solves a parti­ on the pulse generator indicates when a pulse is going into the system. When the units are in phase, cular problem. The Phase Checker, from Sounder Electronics (21 Madrona St., Mill Valley, CA 94941) a bright green light on the phase detector flashes is just such a piece of equipment. at the same rate as the light on the pulse genera­ Why check phase? When signals are out-of- tor. When they're out of phase, a bright red light phase, they cancel (or portions of them cancel). on the phase detector flashes instead of the green Therefore, when recording it's important to be able one. For limited testing purposes, Sounder also to check the phase of microphones, speakers, the makes a pulse generating cassette that replaces the elements within a speaker, special effects, connec­ pulse generator when testing cassette deck/hi-fi/- tors, transformers, and the like. speaker combinations. You might think it's simple to make sure speak­ Construction. The Phase Checker is built ex­ ers are in phase; after all, they all have a little tremely well, and is compact and lightweight (3 label that specifies which lead is positive and lbs.). About the only improvement I could think of which is negative...but those labels can be wrong. would be recessing the controls, jacks, and lights.

Still, it is clearly built to "rock and roll specs", What really turned me on to the Phase Checker was an and would probably survive life on the road better incident in my own studio, where I couldn't figure than the humans running it. out why I had such poor bass response out of my Overall Evaluation. The Phase Checker has one spiffy new speakers, while my headphones sounded large drawback: the two units list for about $450. just great. I checked and rechecked the wiring, and Still, even at that price it's well worth the ex­ it all looked OK. I then checked the speakers with pense to sound companies, speaker manufacturers, the Phase Checker, and wouldn't you know it, the broadcasters, recording studios, and so on. It is speaker was wired out-of-phase at the factory! I unfortunate, though, that the Phase Checker's price was surprised, but according to the engineers at is prohibitive for people with home studios or other Sounder, this kind of thing happens all the time. small-scale setups. Hopefully, Sounder will be able How it works. The Phase Checker includes two to make another, low-cost version for the low end units, the Pulse Generator (transmitter) and Phase market before too long. Polarity Detector (receiver). The transmitter puts In any event, the Phase Checker does what it out a positive-going reference pulse, either at mic says it will do and performs an important test level (0 to 150 mV) or line level (0 to 17V into 4 routine easily and painlessly; probably the last Ohms). It also comes with an internal speaker to word is that it ain't cheap, but you certainly get simplify microphone testing. The transmitter, like what you pay for.------^ 14 POUPHONy — ------—— M a y - August 1982 Robert Carlberg’s ^ WIND PLAYERS VOCALISTS

You can use your own re-view instrument or voice to control any standard synthesizer, Mnemonists Horde (DYS 03). The Weather Report Weather Report with more expressiveness than Mnemonists, a group of eight au- (CBS 37616). Weather Report al­ dio/visual artists with up to bums (this is their twelfth) al­ W a keyboarder eight guests, tend to cause strong ways take a while to sink in. reactions. Heavily cultural yet Zawinul (not Joe or Josef, perhaps hardly traditional, their music is he got tired of people misspelling a heady goulash of five centuries it) provides the motive force, M \ I of musical history with modern writing all but one tune and al­ tape coilaging and electronic mu­ most all of the evocative musical THE GENTLE ELECTRIC sic techniques. It's either a new moments on keyboard synthesizers. PITCH AND ENVELO form of music or not music at all, I'll probably grow to love this FOLLOWERS depending on your viewpoint. Mod­ one too. ern and Medieval wind instruments, o cello, doublebass, electric guitar Charles Brown Bull in a China W rite fo r free detailed and tape manipulations interweave Cabinet (Fracture 101). Elec­ brochure, diagrar in noisy, brash collages that tronic-orchestra rock complete an d app on notes. I p would take a PhD dissertation to with sweeping chords, growling T unravel. See also the Jan/Feb basslines and exploding star- ivies fekfor Aries andI review of their 2nd album. bursts. If you like Larry Fast irc

POUPHONU M ay - August 1982 15 PRACTICAL CIRCUITRY tees that there won't be any weird DC level shifts as you pan the pot. At the same time, notice By: THOMAS HENRY that this lets us preserve DC coupling from the output of the filter. What, another filter? Yes, voltage, which is done to inter­ The wiper of the blend con­ and there's a good reason for it. face more easily with the CMOS trol feeds A2, which is set up to When it came time to design a circuits we'll encounter later. undo the biasing mentioned above. filter for my synthesizer, I was Note that the output of A1 feeds R43 shifts the DC back down to 0V struck by how many exotic designs both the filter proper and also and R35, the output offset trim, already existed - phase filters, R40, the output blend control. lets us trim this precisely. Many polygonal filters, multimode fil­ And as long as we're talking about of you are probably wondering why ters, and filters which did every­ the blend control, let's note that I went to all this trouble, first thing but clean the sink. On the the other side of R40 is at a half shifting the bias up and then back i other end of the scale there were supply bias as well. This guaran- down again. Well, besides the noisy filters, trashy filters, worthless filters, and filters R31 which hardly filtered at all! 1V/Octave 100K What I wanted was a good quality, R13 R14 middle of the road filter - and 50K J1I^ ) 82K V/Oct Trim this design is the result. Envelope In Now, don't get me wrong; I ,hJV W ^ v V - like fancy filters too. But I J2 _6 don't want to play synthesizer in the poor house. The filter I came up with is very clean, but won't cost you an arm and a leg. The good quality at a low price comes from using the CEM-3320 integrated circuit made by Curtis Electro­ music. I think you'll find the unit is very versatile and yet easy to understand. How it works. The name PAL came about because depending on how you adjust the controls, you can have a Phase shifter, All pass Fine filter, or Low pass filter. In Tune addition to the usual voltage R38 controlled options, this unit also 100 features voltage controlled reson­ ance . Referring to the schematic, the heart of the filter is the R19 100K CEM-3320, which does all the hard L - <7> ~ ® ------(4> work for us. In fact, all we really have to do is supply it Audio Input with the correct voltages. For IV example, look at the resonance controls going to pin 9...two 100k resistors is all it takes! R42 is an initial resonance control, and J5 is the voltage controlled in­ put. R28 and R29 convert the input voltages to currents which are then summed into pin 9 of the CEM-3320. (For the purists in the crowd, pin 9 is not quite at vir­ tual ground, but is close enough to pull the summed current trick. Since resonance doesn't require the precision that frequency does, a two resistor summer works quite well.) J3 is the audio input. A1 is - 1 5 V set up in such a way that the audio signal is shifted up to about half of the positive supply

16 POUPHONU M ay - August 1982 CMOS considerations that we'll be low corner frequency. Volt per octave input, and would touching on shortly, the net re­ A4 and its associated compon­ typically be driven by the key­ sult of all this is that we get to ents provides voltage control of board . keep the filter DC coupled from the corner frequency. R37 and R38 R13 is the Volts per octave input to output. In general, I provide coarse and fine tuning trimmer. R30 and R5 drop the like all of my synthesizer cir­ respectively. J2 is an envelope voltage to an appropriate level cuits to be DC coupled if at all input with attenuator, and pro­ before applying it to pin 12 of possible, since this means I never vides a gain of about three. The the CEM-3320. Note that the chip have to differentiate between gain is there so that you can has been temperature compensated audio or control signals. Granted sweep the filter over its entire for all second order effects, you'll probably use the filter for range with a standard 5V output however a first order, or linear, audio processing most of the time, envelope generator. J1 is the one temperature dependence still but there may also be times when exists. If you feel that this is you want to put a jagged control going to be a problem, you may signal into the filter and smooth substitute a 1.8k thermistor for it down by setting a relatively VC Resonance R5, and this will null out all R28 temperature dependence. It has 100K © R41 been my experience, however, that -AAA/— 100 K filters generally don't need the r precision of something like a VCO.

Continued on page 30

Phaser - All Pass" Low Pass Filter Notes AS1-AS4 :% 4 0 6 6 = IC 3 A S5-AS8 - \ 4066= IC 4 Power Supply Connections Assumed: IC2 : pin 7 = —V pin 11= +v IC3, IC4: pin 7= GND p in 14:+ V |= +15V | = “ 15V

OlCircle) Keys the schematic to circuit board

Audio Output THE

R9 R4L 10K FILTER PQUPHONU M a y - August 1982 17 The A REVIEW C V K I . D i oYN d< Y Y By: Ron M inem ier

Unlike other portable synths, Blacet Music Research's "Syn-Bow" offers a radical departure in design by eliminating the key­ board. Just carrying the unit around will attract a great deal of attention with the inevitable first question, "what's that"? General description. The Syn-Bow comes with a redwood case, which must be epoxied together. A nicely stenciled top plate fits on to the case. All controls (save the power switch) mount on the PC board, which in turn mounts to the top panel. This eliminates much point to point wiring and gives easy access to the battery com­ partment and the component side of the circuit board. The total size is 27 long x 2" wide x 1" deep; weight with batteries is a mere 1.5 lbs. Personally, I like the redwood case as it can be finished to taste for a very appealing look, but for heavy-handed types the overall mechanical strength will be intolerant of abuse. The parts (85 in all) are neatly packaged and of good quali­ ty. All pots come with two hex nuts so that you can tighten the pot from the back of the panel, thus preventing scratching or mar­ ring of the front panel. The knobs have two Allen type set screws, and the 7 pin Amphenol interface connector jack is keyed to the panel end not only to achieve proper orientation, but also to insure as torque is ap­ plied to the locking collar the jack will not rotate in its mounting hole. The instruction booklet starts out by saying the kit is not difficult to assemble, and that patience is the key. I would underline that section, for while the board and traces are of high quality, the board is not legended and most of the components mount in rather dense areas. Also some of the smaller capacitors are not marked in any conventional sense

18 POUPHONU M a y - August 1982 Block Diagram of the Syn-Bow

and may confuse the beginner as to There are no strap pegs but these takes the place of conventional what value they really are. Func­ could be added easily, and even filtering; this scheme accounts tional assembly should take about without a strap the unit can be for the organic quality of the two light evenings of work. hand-held quite nicely. Syn-Bow and is what Mr. Blacet has What it does. At the right Circuit description. The trademarked as a "natural filter end of the case is the frequency Syn-Bow's sound source is the patch". As in many acoustic ins­ bow. This is a pot whose knob has ubiquitous Texas Instruments truments, playing harder yields a been tapped into which a 7" plas­ SN76477. While the chip was never brighter tone. tic bar is glued. Moving the bar intended for serious instrumental I cannot emphasize enough the in a circular fashion selects use, with subtle and clever mani­ cleverness with which this some­ pitch. The arc described is about pulation of relatively simply out­ times toy sounding chip is being 40", thus lending good control board chips this design achieves used. For example, the tap off even thought the scale is compres­ sounds which belie the limitations the final buffer feeds a portion sed towards the high end. Total of the 76477. of the audio signal back to a frequency range is 2 to 3 octaves The block diagram (fig. 1) is nominally digitally programmed pin (long time subscribers to Electro­ straight forward. Pushing on the on the TI chip. This in essence notes may remember Craig Ander- sensor drives trigger circuits multiplexes the normal square wave ton's dial controller which des­ which provide several different output with a suboctave of itself. cribes this basic technique). pulses to start the on-chip AD The Syn-Bow may be powered Moving to the left down the amplitude generator, PW sweep sync from two 9V batteries or a M 5 V case you find the power switch, (sweep starts at the same point supply (even if the batteries are then comes the four major sonic with each new trigger), and set still in place). A small external modifier groups. A Decay pot sets the one-shot on the 76477. Trig­ PC board, meant to be housed in the amplitude decay rate, and a ger and gate pulses are also your custom _+15V enclosure, brings Suboctave Mix pot adds a fattening brought out so that you can con­ the gate and trigger pulses up to suboctave. Next is the FM section trol outboard equipment. The sen­ higher levels (nominal output where a balanced triangle wave is sor voltage is also available as a levels are +5V for the gate, trig­ applied to the VCO through Rate control voltage out, although its ger pulses, and CV out). Audio and Depth controls for smooth principle use is to control the output is approximately 2V p-p vibrato. There is also a pulse box marked VCA. The diode VCA and max; there is no volume control. width section with Sweep Rate, 3080 are not mislabelled - the VCA The sound. How does it Depth, and Initial Width controls, is a "diode VCA". With the aid of sound? In one word - good! The which greatly affect the timbre of an RC circuit the ON resistance of range of the timbre produced by the instrument. A foam octagon the diodes is changed via the the initial pulse width control pad at the far left of the unit sensor voltage, thus varying varies the base wave from thin covers a piezoceramic sensor which amounts of signal are presented to nasal to thick and gritty. Adding allows the performer to initiate a fixed gain 3080. You may recall in the suboctave yields a more the note, as well as control tim­ seeing a similar trick used in expansive grit. One limitation of bre and amplitude. The unit can Craig's VC distortion module for the way the suboctave is derived be played on a flat surface or his AMS-100 system. This idea is is that its contribution to the held somewhat like a guitar. a form of timbre enhancement and sound will die away before the POUPHONy- — M ay - August 1982 -jg main wave at longer decay set­ discrete pitch nature and the Overall, I'd have to give a tings. This normally does not triggered source effects, makes lot of credit to John Blacet for detract from the instrument. Al­ for an interesting challenge. As creating a unique, portable ins­ so, at narrow pulse width settings in other intuitive instruments trument which is accessible to the suboctave circuit won't trig­ (trombone, violin, etc.) pitch anyone wanting to express them­ ger properly and does more harm acuity will definitely help. But selves musically. The price (less than good by nearly muting all the this shouldn't scare anybody off shipping) of $124 is pretty acces­ signal. Personally I don't see as you can pick up the device and sible as well. The instrument has this as a problem as I use the get effects right away - doing real character and is fun to play, thin pulse settings for their more formal numbers comes with plus because the SN76477 is being unique voicing qualities, and experience. I think that the bow used, there are a number of mods wouldn't want to muddy it up with idea is basically Jeffersonian in which can give not only the Syn- a suboctave anyway. Sweeping concept, which relates well to Bow sound but also some special pulse width patches have always Craig's editorial statements about effects. Add to that the easy appealed to me and in a circuit portable electronic music; I mean interfacing to other synthesis without any conventional filtering anybody can have a good go at the gear and processors, and you get a blocks this feature is necessary Syn-Bow, but if you wish to really good value for your money. and well done. The LFO that con­ sing with the thing you'll have to trols PW sweep is the TI chip's accept significant responsibility SLF triangle wave. The sync fea­ as well. ture gives predictable effects, but for those who may not want this feature an SPST switch could tions of his minimalist "Anti- be added to defeat this function. re -v ie w Frantic" series of keyboard LPs. The instructions mention that Exotic percussion, more elaborate there is some interaction between CONTINUED FROM PAGE 15 productions, and total reliance on the PW depth and initial controls; Port Said Indian Ocean, Voyage the Prophet 5 make this the most this is not obvious, however at 2/Trail of the Sphinx (Port Said ambitious and therefore strongest long decay times and slow to me­ 001, single). New York duo Stefan Halpern I've heard. Contact Hal­ dium sweep rates you will notice Tischler and Keith K. Walsh play pern Sounds, 620 Taylor Way #14, that not only is the pulse width Egyptian-seasoned synthesizers Belmont, CA 94002. $8.98 plus being modulated, but also ampli­ somewhat reminiscent of Agitation postage. tude. I don't mind this greatly Free's "Malesch". It's an en­ as I like the effect, but if you grossing blend of large synthe­ Gen Ken Montgomery Gen Ken & patch the Syn-Bow into a Pro-One sizers with small (Casio), elec­ Equipment. A musical dadaist in or something like PAIA's envelope tronic percussion with maracas, the fine old tradition of Throb­ trigger + gate extractor this and ancient ethnic influences with bing Gristle, New Yorker Mont­ amplitude modulation is going to the latest E.M.isms. gomery recorded these noisy, wall- produce multiple triggers which of-sound pop songs at home on a may or may not be desired. CASSETTE REVIEWS TEAC Portastudio. Additional The FM section1is perhaps the copies are available for $6 plus weakest link. The modulation DEVO Easy Listening Muzak Cas­ postage from Aeon Import Records, speed only hits the vibrato range sette. No one has been more aware 604 Princeton, Ft. Collins, CO (7 to 10 Hz or so), and the max of the parodies of DEVO (such as 80525. depth is so shallow that any PW the album "Devotees") than DEVO sweep or suboctave mix at the same themselves. It seems only appro­ Rudiger Lorenz Queen of Saba. time will tend to mask the vibrato priate, therefore, that they With a variety of instruments completely. (A simple SPST switch should lead the charge with their including a large self-build modu­ connect the SLF to pin 22, thus own corn-ball combo organ versions lar synthesizer, Lorenz is able to modulating the VCO directly and of their ersatz "hits". Available successfully pull off recording giving your typical phaser gun through the DEVO Fan Club, 9120 these eight tunes direct to tape, sweep sound. While this sound Sunset Boulevard, Los Angeles, CA live without overdubs. That's isn't really in keeping with the 90069, $4.50 plus postage. amazing considering how much is Syn-Bow's original character, it going on in them - and no flubs is available for the price of a David Byrne The Complete Score anywhere. Send $10 (includes pos­ switch.) from the Catherine Wheel. The tage) to Transmitter-Cassetten, Playing the Syn-Bow. It is complete score contains twice the c/o Werner Pieper, D-6941 Lohr- fairly easy to trigger the sensor numbers and maintains a much more bach, West Germany. consistently; there's a trim ad­ coherent flow than the LP of se­ justment for sensitivity. Changes lected highlights (reviewed Jan/- Jimmy Layton Stranger in a in the force applied do yield a Feb issue). The decision to re­ Strange Land. Sample-and-hold noticeable change in tone color lease a cassette rather than one synthi, usually self-triggered and and amplitude. One thing that's double album probably reflects the abstract, with the occasional re­ awkward is that you have to accept skittishness of the industry. lief of a tune or tape collage. the Syn-Bow as a triggered source; $8.98 list at your local record He's at his best when he's having there is no sustain other than store. fun being humorous. Available cranking out the Decay control and direct from the artist at ZYX this is true for the action of the Steven Halpern Hear to Eternity. Productions, 494 29th Avenue #1, sensor parameters as well. The cassette format allows Halpern San Francisco, CA 94121. Playing a melodic line, be­ to stretch out past the restric- cause of the bow rotation's non­

20 POLUPHONU - M ay - August 1982 ELECTRONIC SOUND PISTOLS

An “Almost" Detective Story By: Dr. Andrew L.Gelt

these electronic toys are brought into the country without paying tariffs or perhaps without even going through customs. This gave rise to thoughts such as an inter­ national toy black market that actually smuggles toys into the I recently took along a cou­ US. One distributor said that ple of Electronic Sound Pistols to most of these products were sold a "new wave" gig I was playing, to flea marketers, as well as to and more people asked about the people who sell them to cruise ray guns and their sounds than ship tourists in island countries anything else concerning the band. such as Jamaica, Haiti, and Cura­ These devices emit incredible cao . noises, and the low price reaf­ There even appears to be a firms the importance of technology "knock-off" of the Galaxy Gun 12, as it relates to electronic syn­ the "2100 Space Gun" which retails thesis . for $ 10.99 and also has twelve The "Sonic Fazer" (by Kusan, sounds. Most of the functions rely Inc.) has five sounds, is much on square wave modulation of a VCO larger than competing pistols, and but its extended tessitura is an has the most attention to cosmetic improvement. detail (or should that be"cosmic detail"?). Its red light is in the back, inside the sight and also pulsates with the modulation of certain sounds. Two of the niques as inverted envelope gen­ gun's sounds are "Amplify" (rapid erator modulation and modified LFO sine wave modulation of the square wave width. Unfortunately, VCO and possibly the VCF; the its availability is questionable. small speakers used in such de­ I acquired mine in a local bar for vices might cause equalization $7, but neither the Galaxy Gun 12 changes), and "Radiate" (sawtooth nor its brightly colored box dis­ wave VCO modulated by a sine wave plays a company name, trademark, LFO at .11 Hz (!). I especially patent number, or copyright mark. liked the "Mass Invert" sound Although I obtained the name of a (apparently both audio and sub­ local retailer, he would not allow audio modulation of the VCO). The me to list his company name or other two sounds are labelled address since he didn't want to "Anti-Gravity" and "Ion Trans­ receive inquiries and orders after port" . the product had been discontinued. Parents might be thankful for However, with various other the rather soft volume, but it pieces of information, some inter­ might not be sufficient to drive a esting facts came to light. For­ microphone in a loud rock band eign manufacturers (predominantly without creating feedback. The located in the Far East) often "Sonic Fazer" is the most attrac­ produce forgeries of existing pro­ tive and readily available sound ducts (known as "knock-offs"), and pistol, however. then flood the American market. A At any rate, the Galaxy Gun The "Galaxy Gun 12" has story was told to me about a ship 12 gets my prize for electronic twelve wonderful unnamed sounds, in the Port of Miami with 36,000 sound toy of the year. If you including some sophisticated programmable robots from Korea. I ever see one, grab it! You won't "patches" which use such tech­ got the impression that many of believe the sounds.

PO UPHO Ny- - M ay - August 1982 21 POLVMART SCIENCE The physical and psycho-acoustical background to music is an important part of musical synthesis. Helmhotz’s Sensations of Tone is, a century after its publication, still the standard text for physiological acoustics. Psychology of Music by Carl Seashore, developer of the Seashore Music Test, provides an in-depth analysis of musical style and performance characteristics of many instruments. Music, Physics, and Engineering by Harry Olson, who worked on the first RCA synthesizer, is a thorough discussion of the physical properties and design of traditional musical instruments (plus a chapter on electronic music). Music, Sound and Sensation by Winckel is much like the Helmholtz work, with a bit less detail and more concentration on psycho-acoustics.

# S E N S On The Sensation Of Tone #P S Y C H Psychology of Music # M P E Music, Physics S. Engineering # M S S Music, Sound and Sensation

TECHNIQUE Synthesists must be well versed in a number of techniques and principles. “ How to" and project oriented books are a great way to pick up these skills easily. How to Make Electronic Music by Drake, Herder and Modugno is a standard introductory text for music systhesis classes, with chapters on equipment, tape technique, composition projects, and more. Multitrack Primer by Teac is a step-by-step guide to building, outfitting, and operating your home studio. The Byte book of Computer Music describes computer control of electro-mechanical instruments, Fourier analysis, circuits and loads of software. Home Recording For Musicians is the original guide to outfitting and operating a budget studio for maximum results, including mixer and audio processing circuits and a demo recording.

# H M E M How to Make Electronic Music $ 3 .9 5 #TEAC Multi-Track Primer $ 4 .9 5 #BYTE Byte Book of Computer Music $ 1 0 .0 0 # H R F M Home Recording * 9 .9 5 ELECTRONICS Electronic cookbooks are a great way to stock your library with materials that are not only heavy on theory, definitions, and educational material, but chock full of practical applications as well! These books can easily replace stacks of manufacturers data sheets and applications notes all in an easy to use reference. Walt Jung's Op-Am p and Don Lancaster's Active Filter books are self-explanatory — required reading for synthesists! Audio Op-Amp is an edited version of OACB, containing only audio applications. Lancaster’s C M O S book is much more than a digital reference — phase lock loops, top octave generators, touch switches, and other things you need! Electronic Projects discusses electronic construction technique for the novice and provides 27 projects with PC patterns and a demo recording of the effects NEW Electronic Music Circuits by Barry Klien - Mix or match these circuits to design your own equipment. #O A C b up-Amp Cookbook #C M C B CMOS Cookbook $ 12.95 #AFCB Active Filter Cookbook # E P F M Electronic Proiects2ndedition $ 1 4 .9 5 #AU O A Audio Op-Amp Applications #EM CR Electronic Music Circuits $ 16 .95

REFERENCE Often used reference materials to answer the many questions encountered in everyday synthesis!?)... The Source is over 1 25 pages of patches in universal flow chart notation; the largest publication of its type. Audio Cyclopedia has 1760 pages with 3650 entries and hundreds of drawings and schematics to answer any questions about audio. Polyphony Binders hold up to 1 2 issues of any BV2" x 11" publication without punching holes; keeps issues like new for unending service. Electronic Music Synthesizers devotes the first half of features and functions of commercial equipment (Moog, Arp, Paia, Oberheim, EML, and RMI); the second section provides schematics and projects for the experimenter. #SOURCE The Source $ 4 .0 0 #E I Music Synthesizers $ 6 .9 5 #CYCLO Audio Cyclopedia $ 4 4 .9 5 #BI Binders $ 4 .9 5

HOWTO, NEW ~— How to Build a Small Budget Recording Studio From Scratch by F. Alton Everest - Twelve tested designs How to Design Build & Test Complete Speaker Systems byDavidWeems - A do-it-yourself guide forthe ultimate in sound quality. HowtoMakeSSellYourOwnRecord by Diane Sward Rapaport - The complete guide to independent recording. =$BRS Budget Recording Studio $ 9.9 5 Kl T C S S Complete Speaker Systems $ 7 .9 5 =#MASR MakeSSell Your Own Record $11.95 S k l\/lO R E 4 /8 Track Studio Log Book provides a place to keep aM the important information on your tape library. Log in timing, type of tape used, record patches, make notes and use the expanded track sheet to list sequential changes in tape tracks relating to the settings of the index counter Craig Anderton’s Contemporary Keyboard Articles is a reprint of all the articles from June 1977 through February 1981, covers tips, technique, theory, maintenance, and numerous construction projects. Device Back Issues — during the year that this newsletter was published, it featured almost 200 pages of technical information for the guitarist/musician. A wealth of articles on; design, product reviews, and modification and construction projects. Sold in complete set, individual issues not available, Limited number available, order yours now. Studio Log Book $4.95 Craig Anderton's Keyboard Articles $5.95 “The Craig Complete set (121 Device Back Issues $18.00 A n d e rto n Music Tape" RECORDINGS / V f c ttCORDS Cords - Synergy #ERRO Electronic Realizations - Synergy #SEQU Sequencer - Synergy #GAMES Games - Synergy #ARPT Music For A irp orts - Brian Eno #DELTA Rainbow Delta - Pat Gleeson #CAMT Craig Anderton Music Tape

22 POLUPHONU M ay - August 1982 I------BACK ISSUES I

■ The wide variety of practical applications and construction projects in past issues make a binder full of Polyphonys a V^CASIO M-10 OWNERS , frequently, used reference to keep near your synthesizer, home studio, or workbench. Most back issues are still available for , $2.50 each ppd. Check the issues desired on this coupon and add Did you realize that your pride and joy has ; the total to your PolyMart order (other side), or order by volume and issue number (0304, 0402, etc.) on the PolyMart form. unseen powers? That there are voices and effects that you can add for the cost of a switch and a piece of wire? #0204: 4/76: music notation - timing, external inputs for Gnome, Programmable Drums, Equally Tempered D/A, low cost AR project, digitally encoding keyboards, patches, Volume 1 & 2 This latest booklet from Polyphony gives you the □index. info that you need to transform your mini-axe #0301: _ 7/77: frequency divider project, random tone and gives details on adding a "STUNT BOX", generator project, normalizing synthesizer controls, eliminating patch cords, computer control of analog modules, Chord Egg computer interfacing and much, much, more. □modification, adding pitch bending, patches. #0302: 11/77: The Sensuous Envelope Follower, digital No. CMOD 16 pages ...... $3.50 gates, LED wall art, build a bionic sax, data to music peripheral project, Apple II as a music controller, using the NE566 as a VCO, □patches. #0303: 2/78: computer controled Gnome, using joysticks, build a bionic trumpet, ultra-VCO modifications, voltage control BLANK RACK RANELS □the Mu-Tron Bi-Phase, oral joystick, patches. These easily machined, '/s inch aluminum standard #0304: April/May 78: Minimoog modifications, non-keyboard ■— •module use, phasing and flanging (theory and circuits), memory length rack mount panels are now available from expansion for programmable drums, digitally addressed transposer POLYMART for projects of your own design. project, polyphonic software (with software transient generators), patches, Volume 3 index.

#0402: Sept/Oct 78: electronic music notation, notes on Single size — 13/4 inches in height $6.95(1.50) •“ •the recording of "Cords" by Larry Fast, sequencer software - part one, rhythmic control of analog sequencers, touch switch projects, Double — 3V2 inches in height $11.95(1.50) modular vocoder techniques, PET as a music controller, patches. Triple — 5 inches in height $15.95 (1.50) #0404: January/March 79: add-ons for vocal F and V converter, shorthand patch notation, more on note to frequency cqnversion, graphic monitor project, George Russell, super VCA TO ORDER: — — — — — — — — — — — — — — □circuit, echo software, Vol. 4 index. #0502: July/August 79: hex VCA/mixer project, electronic music schools and studios, modify the Oberheim Expander Module, Tear out this half page order blank. We cannot invoice; payment profile of Ernest Garthwaite, budget microphones, digitizer must be enclosed with your order. To help defray shipping and □projects and software, bar graph ICs. packaging costs, there is a flat $.50 handling fee per order plus j j #0505: January/February 80: Joseph Byrd, Mort Garson, payment of postage costs. MasterCharge and Visa are Tarry Fast on 'Games', composing for 'live plus tape', using the CA3280, recording vocals, ADSR circuits. welcome, but there is a $10.00 minimum on charge orders. Foreign orders must be paid by certified check or money order #0506: March/April 80: Computers in Music: real time audio processing hardware, Powell sequencer system, Max Mathews, in U.S. $ drawn on a U.S. bank (or by charge c a rd ). Phone orders advanced STG software, PortaStudio, phase modulation, Volume 5 □ index. are welcomed for charge card orders only. #0601: May/June 80: Gary Numan, Microcomputers in Real Name: _ Q , Audio, Build a Digital Audio Delay Line, writing Documentation, Richard Hayman Composer/Performer Home Recording: Address: Applying Harmonizing and Pitch Transposing Techniques by: Craig Anderton. #0602: July/August 80: Peter Gabriel, digital VCO City ______S ta te ______Z ip ______Q roject, dream modules, optimum level settings, dynamic phrasing, patches. Card #.______#0603: Sept/Oct combined with Nov/Dec 80: alternate MasterCharge Bank # ______Expiration D a te ______Q ontrollers, add voices to Casio M-10, voltage controlled quadrature oscillator project, cordless patch bay, recording Signature______. rules, patches. Quantity Item Price #0604: January/February 81: Special Construction Edition; uild: Audio Circuit Breaker, Pulse Width Multiplier. Magnetic Harp, 50 Watt/Channel Stereo Power Amp, Quad Sequential Switch, aDOD Mods, patches. #0605: March/April 81: Portable Music Issue, reviews of □ r s FX, E-H Mini-synthesizer, Casio's VL-Tone, plus mods for the M7 IO, GR-500, mini-amp, and the Korg X-911. Introducing; Practical Circuitry and On Location, new columns.

#0606: May/June 81: Synthesizer: Hardware Mods and □ .Software. Mqdular Synthesizer Effects, Environmental music, Keyboard] assignment for the 8700, new columns; Details, Practical Circuitry,I and On Location. Volume 6 index. #0701: July/August: Guitar Electronics: Modify: Fender lAmp, MXR Phase 100, GR-500. Input/Output Structures, $5 Analog .# of items Sub Total Programmer, Sample and Hold technique, Modular Synthesizer Effects, new column: Applied Synthesis, Marketing Your Records. ------S hipping C h a rg e s ------Handling 5 0 . #0702: Sept./Oct.'81: Harald Bode Interview, Live Plus Tape U.S.: add 10a/oof SubldCal □ New Technique, Xenharmonics, Kraftwerk Live - Review, or $5.00maximum Psycho-Acoustic Experiments, Practical Circuitry - Super Controller, Applied synthesis - Brass, Construction Tips For Foreign: 20°/o of Sublotal Beginners. Shipping ___ or $10P°maxinnum #0703: Nov./Dec.|81: Dave Rossum interview, Applied Synthesis: Strings,Details: Series-parallel/Sum-Difference. The SUBSCRIPTION □Sound Gizmo and Pro-One Reviews, Practical Circuitry: VCO Deluxe. u.s. sia/YP. saa/SYRS. #0704 Jan./Feb.'82: Bob Moog interview, Chip Power - F O R E I G N S14/YR. S26/YR. ISTK-050/070, Simple Square Wave Shaper, Tape Timer Ruler, □ SUBSCRPTDN Practical Circuitry: VCAs made simple. Details: Gozinda & Gozouta Revisited, Korg Trident & Casiotone 202 Reviews. Back Issues (from other

#0705 Mar./Apr.'82: Electronic Music Math, Analog Delay Total Enclosed Clock / Modulation; Frequency Domain Modifiers; Screen-Wave for $ □the TRS-80; Touch Switches Revisited; Practical Circuitry: ADSR Return This Half Page the Easy Way; Getting the most out of a Cheapo (Guitar). To: POLYMART P.O. Box 2 0 3 0 5 L J Oklahoma City, OK 73156 POUPHCNL) M ay - August 1982 23 -Tell Them You Saw It In Polyphony-

fers several services for upgrad­ have announced the MA-344 single ing TEAC's Model 2A. Claimed "Qui-FET" op amp and MA-345 dual advantages include improved slew op amp. The company quotes noise rate, lower noise, better drive specs of 8 nV/root Hz at 1 kHz capability, etc. ARCAS will per­ (lower than that of standard bi- form the complete modification for FET type op amps), slew rate of $115, or you can do it yourself lOV/microsecond, and unity-gain with a $65 kit of parts and ins­ bandwidth of 2 MHz. tructions. Optional, high-perfor­ mance outboard mic preamps are also available for $15. A manual describing all modifications is available for $5 (refundable with New from Roland. The Juno-6 parts order). is a 6 voice poly synth with ar- peggiator, digital key transpose Company Update. Electro- (so all tunes can be played in C Harmonix, one of the first effects if you want), chorus generator, manufacturers, nas filed for bank­ and other features; it lists for ruptcy. Those of us who were $1295. The RM-1200B and RM-1600B raised on their humorously named, are 12 and 16 input mixers re­ cheap, sometimes frustrating, but spectively designed for sound re­ musically valid devices are sorry inforcement applications and in­ to see them go. But we wouldn't Switcher. PNP Manufacturing clude features such 4 band EQ for be at all suprised if E-H resur­ (PO Box I, Brooklyn, NY 11204) each channel, two "master" 9 band faces in some form or another in has announced Digipatch, an elec­ graphic EQs, fluorescent bar graph the near future. tronic effect switching center displays for the program-cue-moni­ Imaginearing Audio, origina­ which allows up to three different tor-effects output, and flexible tors of the Alphatone tuners and effects devices to be switched or input structures. The RM-1200B Echo/Digital Recorder, have ceased series mixed for a total of eight retails for $2195, the RM-1600B production of their devices. How­ different combinations. Three footswitches optionally bypass the for $2795. ever, the company still handles all warranty work and will back up effects, with LEDs indicating sta­ any units requiring service. tus . And finally, some good news: Head Games. TEAC's QP-001 rumor had it that Heet Sound Prod­ head cleaner kit ($7.95 list) is a ucts, makers of the "E-Bow", had "universal" cleaner which takes gone out of business. We con­ care of heads, capstan shafts, and tacted Greg Heet to check out pinch rollers. those rumors, and we're happy to report that the E-Bow is indeed alive and well. E-Bows may be ordered direct for $75 postpaid from Greg Heet, 611 Ducommun St., Los Angeles, CA 90012.

Record News. Gramavision New Synth Chip. The MOS Records (260 W. Broadway, New Technology 6581, included with York, NY 10013) has introduced some new Commodore computer pro­ the "New Directions" series, ducts, provides three separate starting with the work "Rainforest voices. Each voice has a 9 octave IV" by David Tudor. Future re­ range, choice of sawtooth, vari­ Power Amp. Who cares about leases will include works by Lukas able pulse, triangle and noise one more power amp? Well, AMP's Foss, Vladimir Ussachevsky, Lou waveforms, and programmable at­ Model 8000 delivers 200 Watts into Harrison, and others. For more tack, decay, and sustain times. 8 Ohms or 350 Watts into 4 Ohms - information, write Gramavision or The 6581 output can be sent dir­ but without a noise producing fan, call (212) 226-7057. ectly into an amplifier without making it well suited to recording any further conditioning. studio applications. Contact AMP, TEAC Model 2A Mods. ARCAS 8440 Paso Robles Ave., Northridge, Engineering (RFD 3, Burt Hill Quiet Op Amp. Analog Systems CA 91325 (tel. 213-701-0249). Road, Winchester, NH 03470) of­ (Box 35879, Tucson, AZ 85740)

24 POUPHCNU — M ay - August 1982 p Audio Modules MOSFET Power Amplifiers N ew EQ. Loft (91 Elm St., Claimed S/N ratio is 84 dB with •BUILT-IN HEATSINKS ‘ ONLY 5 CONNECTIONS Manchester, CT 06040) has an­ 0.2% THD; the chip also features REQUIRED * 5 YEAR WARRANTY nounced the Model 401 parametric summing node signal inputs, linear Choose ILP MOSFET power amps when you need the ut­ most in performance without spending big money. They EQ with four overlapping frequency and exponential gain control, and provide the fastest possible slew rate, low distortion at bands, continuously adjustable high frequencies, -i better thermal stability MOSFET low control voltage feedthrough. power amps work with complex loads without difficulty frequency, adjustable bandwidth, and without crossover distortion. Three models are Contact SSM at 2076B Walsh Ave., available, with integral heatsink to mount on your own and selectable boost/cut. Mount­ Santa Clara, CA 95050 (tel. 408- chassis (optional rack mount cabinet available). Con nection is simple — via 5 pins. MOSFETs can be com­ ing in a 1.75" rack mount, the 401 727-0917). bined with other ILP modules to create almost any audio system, whatever your age or experience. claims THD of 0.01% and a noise Ultra-fi specifications: Slew rate 20Vus. Rise time 3 us. S/N ratio 100 db. Frequency response ( 3 db) 15 Hz • 100 level of -92 dB ("A" weighted). kHz. THD (Typical at 1kHz) < 0.005%. IMD (50Hz/7kHz 4:1) <0 .00 6 % . Korg Trident Update. Korg MOS120 60W/4-8U (requires ± 45V) $79.95 MOS200 120W/4-8S1 (requires ± 55V) $129.95 New from SSM. The SSM2100 is (89 Frost St., Westbury, NY MOS400 240W/4S1 (requires ± 55V) $199 95 11590) has introduced the Trident a complete monolithic subsystem to WRITE FOR FREE CATALOGUE LISTING Mark II, which retains the fea­ •BIPOLAR POWER AMPLIFIERS ‘ HI FI PREAMPS realize logarithmic and exponen­ •MIXERS • POWER SUPPLY UNITS ‘ CABINETS tial transfer characteristics. It tures of its predecessor but also . ‘GUITAR PREAMP and more includes two precision op amps, a adds advanced programming capa­ high conformance transistor pair, bilities, with double the program storage and full Edit and Tape GLaOSTOHE and a precision bandgap reference. Electronics 901 Fuhrmann Blvd., Buffalo, NY, 14203 Interface capabilities. The all- CALL (716) 849-0735 to order. Have your Applications include log sweep VISA or MasterCard ready. For information generators, linear to dB conver­ new synthesizer section includes call (416) 787-1448 or circle reader number. two full ADSR envelope generators Dealer/OEM enquiries (416) 787-1488. In sion, and analog compression/ex­ Canada: Gladstone Electronics. Toronto. pans ion. per voice, programmable attenuator and auto damping, plus an improved The SSM2022 is a low cost, 24 dB/octave filter and better THE PERFECT high performance dual VCA. noise specs. COUPLE TRS-8 0 and PA I A* Your *TRS—SO will PLAY ENTIRE COMPOSITIONS back through ANY SYNTHESIZER with the help of a D/A converter and some *PAIA 8781 QUASHS.Below are some of the added features. > PLAY at up to 256 SPEEDS > The FEWER CHANNELS you use the LESS MEMORY YOU USE. (runs on a 16k TRS-80 model 1) > THROW AWAY YOUR SPLICING BLOCK because you will be able to MOVE WHOLE SECTIONS OF A TUNE FROM ONE PLACE TO ANOTHER > INSERT ,DELETE or EDIT parts of your compositions. > Choose whether you want HARDWARE ADSRS or SOFTWARE TRANSIENTS. If you choose SOFTWARE ADSRS you will be able to DRAW THEM on your video display using a $20.00 LIGHT PEN. For more information PHONE or WRITE to: When writing to change the address ATTACH OLD LABEL HERE on your POLYPHONY subscription SEE-THRU ENT. 933 Frank Ave. it is important that you enclose the Windsor,Ontari o. mailing label. Our computer cannot Canada N8S 3P4. locate your name on the subscription NEW ADDRESS 24 HOUR PHONE DEMO LINE list without it. 1-519-735-2995 Name______mail to: POUPHONa Address______*TRS-80 is a trademark of Tandy Corporation. PO BOX 20305 City------State------Zip. *PA1A is a trademark of PAIA Oklahoma City,OK 73156 ELECTRONICS. POUPHONU M a y - August 1982 25 Understanding Digital Synthesizers:

By Dave Wilson

A while back I started think­ ing about building a digital syn­ 10 REP ##******^#********4**************************************************** thesizer, because I have a micro­ 1 * ORIGINAL PROGRAM FEB-'32, THIS VERSION 3/3/32. * 1 * DIGITAL MULTIMODAL 6 db/OCTAVE FILTER CPAiA 4738, EML 101, ETC.) * computer (OSI Challenger-IP) and 1 # PROGRAMMED BY DAVE WILSON OF LLAMA SOFTWARE, A DIVISION OF THE * because my knowledge of hardware 1 * CHEERLEADERS CORPORATION, 1102 MERRITT ST., FAIRFIELD, CT 06432 * * is dwarfed by my knowledge of 1 * LINES 360-440 ARE A DIGITAL OSCILLATOR FOR DRIVING THE FILTER. * software - the one thing I can LINES 460-430 ARE THE FILTER ITSELF (JUST FOUR LINES! SIMPLICITY!)# always do without guessing (like I LINES 510-630 ARE A PRINTOUT ROUTINE THAT PRINTS H'S FOR THE # HIGH PASS CURVE, L'S FOR THE LOW PASS CURVE, B'S FOR THE BAND PASS# sometimes do when I wire op amps). CURVE, N'S FOR THE NOTCH CURVE, AND I'9 FOR THE INPUT CURVE. * One of the problems with digital THIS PROCRAM WAS TRANSLATED INTO FORTRAN TO RUN AN ANADEX PRINTER/* PLOTTER FOR NICER OUTPUT. THE COMPUTER USED IN EITHER CASE IS A * synthesizers is the implementation PDF-11/34 BY DEC WITH THE RSX U M OPERATING SYSTEM, * of standard filters (low pass, * band pass, etc.) with digital 160 REM #**♦**##******#*##**#*******#********###*#*#»#*****##******##*#»♦♦*#** circuits/programs. After playing 200 P*Q 2 1 0 L-0 with a little calculus and the 220 B=0 schematic to PAIA's 4730 multimode 230 PRINT ’FREQUENCY (0 TO l ) AND Q 0*0) 240 INPUT P,Q filter, I came up with these four 250 IF F<0 equations for the four outputs of F> 1 the filter: <0 THEN ___ “INPUT~WAVEFORM: 1=RAMP, 2=PULSE/SGUARE, 3=TRIANGLE, Highpass 232 IF W * 1'THEN 270 235 IF W>4 THEN 270 290 IF WOINT(W) THEN 270 1 300 IF W<>2 THEN 340 ' X BPass - LPass - Input 310 PRINT "PULSE WIDTH CO TO. 1001) 320 INPUT P 1 + Q .330 IF P<0 THEN 310 *335 IF P>100 THEN 310 340 REM COMPUTATIONS START *«**#***«*♦#*#******************##**«** 350 FOR K«t TO 100 Bandpass = -fc X \Highpass dt 360 ON W 00 TO 370,390,420,440 P§ 370 I--K/100-.3 380 CO TO 450 390 I*-.5 Lowpass = -fc X ^\Bandpass dt 400 IF K<*(100-P) THEN 450 ■405 I = .5 410 CO TO 450 420 1“ABSC50-K >/50-> 5 Notch = (Lowpass + Bandpass)/ 2 GO TO 450 IN<1*.06283) . : REM FILTER STARTS HERE ************************************************** These equations seem correct in that they behave exactly like 4/0 B=B~F*H 480 L=L-F*B the filters they were designed to 490 N*(L,H)/2 replace. If you approximate the 500 REM THAT'S THE WHOLE FILTER! ******************************************** integrals (yes, those funny look­ S10 A$=“ 520 P1 *!i,5+L)*40 ing squiggly lines are intended to 530 P2= C1,5+B)*40 be integral signs - pardon my word 540 P3= C1,5+H)*40 processing!) over time by just 550 P4= f1.5+N)*40 560 P5=<1,5+1!*40 adding (the other name for inte­ 570 A*=SEC* ! A*, 1, P1 - 1 ) •+" L" +SEGS < A*, PI +1, LENS A*) S gral calculus is SUMatory calcu­ ■ AS*SEG* < A*, 1,P2- 1) + "B"+SEG*(A*,P2+1,LEN(A*)) lus), then if the sampled rate is A4=SEG*(A*,1,PS-i>+"H-+SEGS!A*,P3+1,LEN(A*)> high enough to be inaudible, the *vu A*=SEG*(A*.l,P4-i>+"N“+SEG*) l,P5-i)+"I“+SEG*) error introduced by the discrete REM USE A*=LEFT* + *’L"+RIGHT* < A*, PI + 1 ) summations will also be inaudible. A* Now picture the digital syn­ thesizer. To make it simple, we'll look at the processing of an The analog to digital (A/D) string on the guitar, and the external signal: and digital to analog (D/A) con­ sound is sampled 50,000 times. verters merely allow the signal to Each little sample is fed to the Guitar---A/D Converter---Digital exist in a form which the digital synthesizer where the four equa­ Synth-- D/A Converter---Amp synthesizer can use. You play a tions are applied (in the order 26 POUPHONy- M a y - August 1982 given) and one of the output vari­ And there you have it - a contains the following software ables - let's say bandpass - is look inside an (oversimplified) modules: fed out through the DAC to the amp Digital Synthesizer showing what and speakers. If we use a high it does. To provide more detail, 1. A software "VCO" with (greater than 5) value for Q and I have written a small program in five available waveforms. change fc from 0 to 1 and back to BASIC which will run on most home 2. The filter. 0 over a few seconds, the result computers. It doesn't work in 3. A software oscilloscope is the classic "wa" sound. The real time; that is, you can't with five beams - eat your heart digital synthesizer is nothing actually filter sound with it, but out, Tektronix! more than a computer solving the you can plot with it and then It should be noted that two same four equations over and over compare the output it produces to running totals are kept by the again for new values of INPUT, fc, the output of an analog filter as program given in listing 1; the and Q. displayed on a scope. The program values of L and B (lowpass and

High Pass

Notch

POUPHONL) M a y - August 1982 27 bandpass) from the previous solu­ output will depend on the values Deanza Image Processor used to tion of the equations are used in of these variables, i.e., what store the images before printing. generating the next solution. state the filter is in when the To drive the Deanza, the whole There are the "running totals" inputs are received. program had to be translated into that serve as our integrators. In looking at the sample RUNs FORTRAN and modified somewhat - Their analog counterparts are the of the program (figures 1-5), one the bottom line is that your out­ capacitors in the VCF, and if point should be made: the BASIC put will resemble what's shown you've ever wondered why the fil­ program is intended to run on any here, but it will be cruder (un­ ter is called "state variable", home computer and plot by printing less you own a graphics program well, these two variables ARE the letters on the paper or screen. and beef up the program a little). state variables, because for the For demonstration, however, the Line 620 shows how to translate same instantaneous values of IN­ outputs shown were made on an the SEG$'s used in lines 570-610 PUT, fc, and Q, the values of the Anadex printer/plotter, with a into the more standard LEFT$ and

3. SQUARE WAVE FILTERED WITH FC= 0.8, Q=10

28 POUPHONy M a y - August 1982 RIGHT$. Line 510 is simply 132 overlapping all five waves (the of their VCF manual entitled (or thereabouts), spaces being four outputs plus the input). 'Scope Art, showing some of the store in A$, and the output is 132 This is the style of output of the fun pictures analog filters can columns wide. To run on 80, 64, BASIC program. make. or 40 columns, change the *40s in Figure 4 shows the same wave­ Sine and triangle inputs look lines 520-560 to a lower number forms as in figure 3 (square wave, rather boring, so there aren't any (like *20 for 80 column). Don't fc = 0.8, Q = 10) but separated examples of these. The reason is change the 1.5+s, as they seem to out so that they are separately that there just aren't that many work fine just the way they are. visible. harmonics in a triangle wave (and Figure 1 is a Ramp wave fil­ Figure 5 shows the phase none in a sine wave) to filter tered at a relatively low fc, with relationships of the lowpass and out. Q = 0. bandpass outputs by plotting one Many things happen inside a Figure 2 is a narrow pulse vs. the other. This picture (when digital synthesizer, but filters filtered at a higher fc, with a Q drawn on a scope by an analog are probably the most complex. I of 5. Note the ringing and the synthesizer filter) appears in hope my digital filter has helped relative phase of the LP, BP, and much synthesizer literature - ARP others understand digital synthe­ HP outputs. user manuals, older CFR cata­ sizers; .it has sure helped me a Figure 3 shows the phase logues, Aries data sheets, and lot. _ relationships of the outputs by PAIA even has a section at the end

POUPHONU M ay - August 1982 29 1 REM THESE ARE THE CHANGES 2 REM NEEDED TO RUN THE 3 REM FILTER PROGRAM ON AN 4 REM APPLE II COMPUTER REM 170 DIM A*<40> 585 REM A*=40 BLANK CHARACTERS 510 A * = tl

520 PI = <1.5 + L> * 13.3 530 P2 = <1.5 + B> * 13.3 540 P3 = <1.5 + H) X 13.3 550 P4 = <1.5 + N> X 13.3 560 P5 = <1.5 + I) * 13.3 570 A* = LEFT* < A* , P 1 - 1> + ii l ** + RIGHT* - p 1> 580 A* = LEFT* - P 2) 590 A* = LEFT* < A* , P3 - 1) + “H" + RIGHT* - P 3) 600 A* = LEFT* < A* , P4 - 1) + "N" + RIGHT* < A* , LEN < A*) - P 4> 610 A* = LEFT* < A* , P5 - 1) + " I *' + RIGHT*

PRACTICAL CIRCUITRY comparing accuracy at different Continued from page 17 Calibrating the PAL. Follow octaves. So far, we have examined the this procedure exactly: Applications. First, set SI standard features which you might 1. Turn R39, R41, and R42 to the low pass mode and turn expect to see with ^ny filter; now down completely. Turn R37 and R38 blend control R40 to full strength let's look at the single most to the center of their rotations. filter output. The filter is now unusual feature of this circuit. Monitor the output at J4 with an acting like a standard low pass AS1-AS8 are analog switches (each oscilloscope or multitester (the filter. is 1/4 of a CD4066), and have been higher the impedance, the better). Next, put SI in the all pass set up pairwise to form single 2. Turn the blend control, mode and keep the blend control on pole, double throw switches. Es­ R 4 0 , for full filter out put. Ad- full strength filter output. sentially each one of these SPDT just R34 until the output reads Sweep the coarse frequency con­ affairs will switch the tuning OV. trol, R37, and notice the pitch capacitors either between ground 3. Turn the blend control, shift characteristic of all pass or the input resistors of the gain R40, for full straight signal at filters. cells. With the capacitors hooked the output. Adjust R35 until the Now keep SI in the all pass to ground, you have a low pass output reads 0V. mode, but blend in some straight filter; when they're swung to the 4. Repeat steps 2 and 3 signal. Sweep the coarse control gain cell input resistors, you get until the output reads 0V no mat­ and notice the typical "swooshing" an all pass filter. I used elec­ ter position R40 is in. sound of a phase shifter. tronic switching for several rea­ 5. Now turn R39 up full and As I mentioned in the opening sons: first, who wants to solder apply a 1 Hz signal to J2 (use the paragraph, there are lots of fil­ all those wires! Besides, a cou­ LFO from your synthesizer for this ters around and some of them are ple of 4066s are less expensive if you want). The signal should hard to use. I think you'll find than a ganged, rotary switch (one be about 10 V peak-to-peak in this one is exceptionally easy to ordinary SPST switch, SI, does the amplitude. Now while monitoring use, yet has enough novel features job now). the output, adjust R4 for minimum to make its inclusion in any syn­ A3 is set up as an inverter control voltage feedthrough. thesizer system worthwhile. And so that when one side of the 4066 6. Finally adjust R13, the by the way, in my original proto­ switch is enabled, the other side Volts per octave trim. This is type I had some front panel space is disabled. Since I used a quad best done with your keyboard left over, so I included the ADSR op amp for this project, and had hooked up to Jl. Set the filter circuit I presented here several one op amp left over anyway, it into oscillation by turning re­ months ago. Let me tell you, an was convenient to do things in sonance control R42 full up. Now ADSR and VCF combination makes for this manner. tune the filter like any VCO by a great pair! Happy building! ■

30 POUPHONU - M ay - August 1982 The Realistic MG-1 Synthesizer A R eview

by: Chuck Pogan ____

I doubt there is anyone read­ "sync" switch and a "detune" sli­ The "Poly" section is most ing this publication who has never der. Two tuning knobs on the curious. With the mono section been to Radio Shack; this store upper left hand of the instrument silent (mix sliders down), turning has done for electronic hobbyists control the master tune (all os­ up the "Poly" slider generates a what McDonald's has done for ham­ cillators), while the "Polyphony" fully polyphonic organ-like tone. burgers (and there are more Radio control determines the frequency Add the mono section sliders and Shacks than McDonald's - ed.). span between the two TGs. bingo, you hear a lush multi­ This is not to imply that The 24 dB/octave low pass layered orchestral sound, and the small semiconductors and related filter has three sliders control­ mono section takes on a polyphonic items are their only strong suit - ling the cutoff frequency, peak playing characteristic. the "Shack" has recently proven emphasis, and the response to the Pros of the MG-1. The MG-1 stiff competition to all major envelope (contour) generator. A can be easily patched for the many stereo and computer specialty com­ three position fi1 ter/tracking musically useful sounds in the panies . switch selects full keyboard mono section. The filter sounds In the course of their expan­ tracking, half keyboard tracking, okay, and the oscillator stability sion into other fields, the Shack and no tracking. seems fine. The "Poly" sound, has gotten together with the Nor- The contour generator is an when mixed with the mono section lin Co./Moog brainiacs and pro­ attack/release type envelope trig­ (set for no sustain), affords a duced a polyphonic synthesizer ger. You can bypass it using the rich, textured'tone that is pro­ which they claim is the best buy, "in-out" sustain switch and have bably the best patch on the unit feature for feature, of any synth it "repeat" the envelope at the and sounds as good or better than around. Well, let's put their LFO clock rate. The LFO section a lot of more expensive organs. "Concertmate MG-1" through its offers sine, square, and sample- The Shack also had the foresight paces and see for ourselves. and-hold modulation. Two sliders to include an aux input plug for Overview. The unit itself control the amount of designated future computer control and the appears to be solidly built. The modulation sent to the oscillators like. face panel, at first glance, seems (both simultaneously) and/or the One of the major advantages almost over-simplified , with filter. to buying a synth like the MG-1 is plenty of room between all con­ The mixer section has separ­ the expected speed of service trols. All control functions are ate volume output levels for the should the need arise. Radio color-coded and laid out in the two oscillators, a noise level Shack prides itself with respect now expected performance synthe­ output, and a "Bell-Tone" slider to service, and if you're a syn­ sizer arrangement of LFO, OSCs, which seems to be an additional thesizer owner who has had to have filter, env. generator, and mix tone with a complex waveform. The repair work done, I'm sure you output. latter is a much more harmonic will agree that fast service The instruction manual uses sound than its name would imply, should be a "top-three" priority the "welcome to the wonderful and is a nice, if not unusual, when buying a synth. Considering world of the electronic music addition. the "name-brand" manufacturer and synthesizer" type of approach So far, the unit has met all the widespread Radio Shack repair which may ruffle the feathers of a of the basic mono synth require­ services, you should have minimal more conventionally schooled syn- ments. But the inclusion of the problems in this regard. thesist. Terms like oscillator "Poly" slider is what interested Cons of the MG-1. The "Poly" are renamed (for simplicity's me the most. feature could have a lot more sake) "Tone Generator" and the envelope generator is called "Con­ tour". Since the new terms are still self-explanatory, there should be no confusion as to their functions. The two Tone Generators (TG for short) each have a three- position octave select switch. TG #1 can transpose one or two oc­ taves down while TG #2 transposes up one, down one. Choice of wave­ forms on #1 is sawtooth or square and on #2, sawtooth or pulse. TG #2 also includes an oscillator

PO UPHO Ny- M ay - August 1982 31 ADVERTISER INDEX

Analog/Digital Associates ...... 13 Dickstein Distributing Co...... 32 Digital Multi-Media control ...... 15 Eternal American Productions ...... 38 Gentle Electric Co...... 15 Gladstone ...... 25 Larson Music Co...... 7 PAIA Electronics, Inc...... 32 & 44 Pandora ...... 9 PGS Electronics ...... 41 Polymart ...... 22 & 23 Polyphony ...... 13 See-Thru Enterprises ...... 25 Sequential Circuits ...... 2 SMS ...... 43

potential if the poly tone could This is the Shack's first be controlled by the contour gen­ contribution to the synthesizer erator. As it stands now when market, and they are approaching using the mono section in conjunc­ this area gingerly. But perhaps tion with the poly section, the because of the market they are poly tone will decay the moment trying to appeal to, they have your finger leaves the key (like kept the unit overly simple and The first thing you'll notice about Craig Anderton's an organ), leaving the mono sound overlooked some minor modifica­ latest PAIA kit is what careful design and input/output compansion does for noise levels. This is an incredibly (if any decay is used) to linger tions which would have make the quiet effect useful both in the studio and live process­ on. This also causes a noticeable unit instantly recommendable. ing. amount of false triggering and Whether or not the MG-1 is But continuing the PAIA trend to quiet quality isn’t the only thing that makes the Hyperflange & Chorus an ex­ "glitching". The mono source will for you, I really can't say. It ceptional value. The Hypertriangular control oscillator dart to whatever key is released has enough appealing features to based on a Curtis 3340 VCO chip allows both linear time sweeps (the way everybody else does it) and the ex­ last. As mentioned before, when at least warrant a "test drive" ponential sweeps (whjch is the way your ears really the mono section is set for no VCA (as the Shack would say). You may prefer) both over a 72:1 range. And an exclusive decay, the poly sound is real even find the unit's strong points Resonance Lock Circuit lets you hang regeneration “ on the edge” without having to worry about breaking into good. But try to get cute with are worth the suggested price. feed-back howls. the VCA on the mono section and But in the meantime, I'm More? OK, how about control features like a pan pot for hoping they will have Norlin modi­ dry and processed signal, + or - flanging, clipping in­ mix it with the poly tone, and dicator LED for precise setting of optimum input signal you're in for a tough time. fy this unit to compete head-to- level, separate external control inputs for both LFO and head with the big-name brands. time delay...even a sync input for the control oscillator. The Hyperflange & Chorus comes in a standard 1 % inch General evaluation. I don't What I'd like to see is a unit rack mount configuration compatible with other pro­ expect Norlin to put the same with the extras I mentioned be­ ducts in the 6700 series of equipment and requires ± 12 fore, even if it costs a bit more. to 15 volt 200 ma. power supply. keyboard triggering system in the Then Radio Shack would be able to No. 6750 HYPERFLANGE & CHORUS KIT MG-1 as the Polymoog, but it would have made for a much more playable compete with other synthesizer $149.95...... 3 lbs. instrument if a more reliable manufacturers as equally as they ORDER TOLL-FREE WITH multiple trigger were included. do with the stereo and computer VISA OR MASTER CARD And if the poly tone could be companies. treated by all the synth's func­ Still, try it out for your­ 1- 800 - 654-8657 tions (LFO + VCA) and triggered self. Knowing the type of people Direct mail orders & inquiries to: simultaneously with the mono sec­ who read this magazine, I'm sure tion, this would create a superior you'll find yourself near a Radio BMA Electronics, Inc. unit. Shack in the near future anyway 9 1020 W W ils h ire , O kla ho m a C ity , O K 73116 ■ (405)843 9626

32 POUPHONy M a y - August 1982 FEATURES Vol,Iss:Pg. Analog Delay Clock/Modulation, Boileau 0705 26 Anatomy of a Private Record, Carlberg 0706 8 Casiotone 202 Review, Styles 0704 28 Chip Power, Orman 0704 8 Component Profile SSM 2033 & 2044, Helfrich 0706 36 Electronic Music Math, Anderton 0705 6 Electronic sound Pistols, Gelt 0706 21 Frequency Domain Modifiers, Beigel 0705 12 Getting the Most out of a Cheapo (Guitar), Legg 0705 25 GR-500 Modifications, Loney 0701 28 Interview: Harald Bode, Lee 0702 14 Interview: Robert Moog, Lee 0704 10 •I Interview: Dave Rossum, Lee 0703 23 Interview: Don Slepian, Schwartz 0706 10 Kraftwerk Live, Pogan 0702 27 Korg Trident Review, Rhodes 0704 30 Live Plus Tape (technique), Meyer 0702 18 Modular Synthesizer Effects, Aikin 0701 30 Optical Audio, Lisowski 0706 34 Phase Checker Review, Anderton 0706 14 Pro-One Review, Pogan 0703 32 Psycho-Acoustic Experiments, Lauria 0702 36 Realistic Mg-1 Review, Pogan 0706 31 Sample & hold composition Technique, Collier 0701 13 Screen Wave for the TRS-80, Lisowski 0705 8 Sound Gizmo, Gelt 0703 22 Synbow Review, Minemar 0706 18 Taking Control of Your MXR Phase 100, Richards 0701 25 Touch Switches Revisitied, St. Pierre 0705 16 Understanding Digital Synth’s,A Digital Filter, Wilson 0706 26 Xenharmonics, Two Essays, Darreg 0702 23

PROJECTS

Build a $5 Analog Programmer, Austin 0701: 9 Cable Test Fixture, Fuglewicz 0704:15 Construction Tips for Beginners, Jones 0702:26 Fender Amp Modifications, Powell 0701:22 Remote Switching for DOD 500 Processors, DiFrancesco 0705:41 Repair Tips, Sloan 0704:15 Simple Square Wave Shaper, Beausoleil 0704:24 Tape Timer Cut-Out, Anderton 0704:34 Tube Tip, Michaud 0701:12

COLUMNS

Applied synthesis, Rhodes Marketing your Records 0701:21 The Brass Family 0702:12 Electronic Keyboard Sounds 0706: 6 Strings 0703:18

Details, Bohn Basic Training 0706:39 Earth, Dirt, Rocks and Ground 0702:33 The Story of Gozinda & Gozouta 0701:26 Gozinda & Gozouta Revisited 0704:22 Series Parallel/Sum-Difference 0703:14

Practical Circuitry, Henry ADSR the Easy Way 0705:22 The PAL Filter 0706:16 Super Controller 0702:26 Tricks with the SN76477 Pt. II 0701:16 VCAs Made Simple 0704:16 VCO Deluxe 0703:28

On Location NYC 70th AES Convention, Petersen 0703:26 1981 Computer Music Conference,Wilson 0704:14

Current Events 0701:10; 0702:10; 0704:20; 0705:20; 0706:24

RE-VIEW, Carlberg 0701:8; 0702:6; 0703:10; 0704:21; 0705:28; 0706:15

PCUPHONy M ay - August 1982 33 Conventional audio synthesizers are really A guitar could also use light beams instead of special purpose analog computers; dedicated cir­ strings, in fact, such a device was described at the cuitry (filters, level shifters, and so on) process 1981 AES show in New York. Interrupting or reflect­ a basic audio waveform to produce some desired (mu­ ing the beam as it travels to various sensors could sical) result. Traditionally, most musical instru­ allow for chords, notes, and different styles of ments (and computers) have been mechanical and elec­ "picking or plucking". trical in nature. However, optical analogs of these Optical cable. Fiber optic cable can also devices are possible, which opens up the possibility replace the usual metal shielded wire cords that of optical synthesis devices. transfer audio signals from instruments to mixing Optical devices are not unknown to audio. boards or amplifiers. Not only are fiber optic You've probably seen optics used in existing audio "wires" smaller and lighter, unlike standard cords equipment, such as wa-wa pedals and end-of-tape they will not act as antennas capable of picking up sensors. Also, opto-isolators have been applied to 60 Hz hum or power switching spikes. Off- the- audio signal control and processing since the 50s. shelf fiber optic "Y" and multiple connectors can But, these are examples of rather low level optical provide patching and splicing. Of course, it is methods and are primarily electrical in effect. also possible to completely do without cords and An optical keyboard. Figure 1 shows something transmit light beams through the air; there would be that is more purely optical, namely, an optical a "transmitter" at the instrument which would modu­ keyboard. It consists of a light source and an late an infra-red LED, and a photo-sensitive "re­ array of beam splitter prisms, each of which divert ceiver" at the amplifier. However instead of infra­ a portion of the source light beam in an outward red beams, perhaps beams in the visible range could direction. Adding matching light detectors creates be used to give a combination of light show and a set of simple "switches", since a finger touching audio event. As long as the ambient light isn't a OPTICAL AUDIO By: James Lisowski

the prism surface reflects light back on to the problem, the modulation scheme could even shift the detector, thus closing the "switch". Besides its frequency (color) of the beams, thus giving a "color novelty, there are several real benefits: organ" effect. • "Solid state" operation means no moving parts. Creating a keyboard out of thin air. Imagine • With suitable depth of field, an optical this: instead of a physical keyboard, consider a keyboard can sense velocity and attack. hologram of a keyboard (or other instrument) pro­ • The keyboard is optically isolated, thereby jected into the air. Anyone looking at the scene minimizing any possible shock hazard. sees a keyboard, where none actually exists; there

Fig. 1 Keyboard Elements

34 POUPHONU M a y - August 1982 is only an image in the air. But interaction with common electronic synthesizers. Not only that, the this optical image can be sensed by noting the materials used in optical audio are easy to manufac­ interference the player's fingers make within the ture. For instance, a solid crystal block can dy­ "space" of the image (this could be realized with namically alter the frequency or phase of light optical/electronic computers or video pattern recog­ passing through it by a property known as bifur- nition equipment). Thus, you could "play" the note gence. Doing such things as "pitch bending through associated with a key on the holographic keyboard - touch", that is, stressing the optics to change the and could even move the image of the key down in frequency, could give the conventional type of human space, making the key apparently respond as if it control over an optical oscillator. Devices such as were a "real" key. pulse mode-locked lasers (devices which give off This idea opens up a whole realm of possibili­ pulses at equally spaced intervals) could act as ties...for starters, how about multiple keyboards in frequency sources or synchronization references small regions of space at any angle or three dimen­ (metronomes or click tracks). Again, using reflec­ sional location arrangement, instant instrument tive or other optical techniques, it's possible to redefinition, patch call-up, or change in micro­ make frequency multipliers/dividers (just like the tonicity? Keyboard images could be switched in and electronic ones) by shifting the light frequencies out from under your hands faster than it would take up or down. You could also alter the amplitude to move physically from one "solid" keyboard to (brightness) of the light to create low frequency another. Key and control layouts would not be oscillator effects. Naturally, like conventional limited by physical construction design limitations, synthesizer components, these devices can be used and as a bonus, setup time would be reduced (there for control purposes as well as being sound sources. would be fewer bulky boxes to stack and lug around). An optical bandpass filter. Ordinary colored I'm sure you can think of other new tricks to be optical filters can be used in the same manner as done with a "virtual keyboard". fixed electronic filters (high/low cut or bandpass The optical synthesizer. Up to this point, filtering). The components shown in figure 2 might I've been discussing optical input and output de­ be found in a photospectrometer. In this example, a vices that are not that far removed from conven­ beam of white light (many different wavelengths) is tional end-of-tape switching. Let us now make a refracted (spread into its component wavelengths) by leap to the optical computer/processor/synthesizer. a rotatable prism. The refracted rays pass through As you may remember from high school physics, a narrow slit in an otherwise opaque material, which the electromagnetic spectrum covers a long, continu­ allows you to choose various frequency ranges at the ous range of frequencies. The audio signals we output end. Known as a monochrbmator, this is an normally encounter in synthesis are in the lower adjustable optical bandpass filter. Like the elec­ regions; as we move progressively higher in the tronic audio bandpass filter, this one can be swept, scale of energy events, we find radio waves, IR/- held fixed, or have its pass bandwidth changed since visible/UV light, X rays, and Gamma rays. The main you can pick and choose which frequencies to trans­ point is what we can do to waves in one part of the mit by rotating the prism. These signals could be EM spectrum, we can do to waves in other parts of simple audio encoded frequencies, or they might be the spectrum. entire channels of information (several audio or For example, we could construct an optical control signals modulating a "carrier" frequency). oscillator with the use of lasers, lenses, optical This gives you the equivalent of a channel selector- filters, mirrors, and other optical components. /mixer in one device. Several could be cascaded for Although the output is far removed from audio fre­ more complex filtering or routing. Now, start ad­ quencies, we can translate it downward with familiar ding lenses, mirrors, modulators, inverters, ampli­ techniques such as heterodyning. When you mix two fiers, splitters, multiplexers, delay lines, mixers, very close frequencies together (even optical fre­ and you get an idea of how similar optical synthesis quencies), a beat or sum and difference frequency processing is to conventional electronic synthesis develops; once you've done that, you've changed processing. Remember too that these are mostly optical into audio. Because of the very high fre­ analog methods - you can have digital optical con- quency ratios involved, the range or bandwidth of trol/processing as well. The world is wide, and not the optically produced audio far exceeds that of all electronic...so see the light! — ______

F ig .2 Optical Adjustable Bandpass Filter

r o u p t m M ay - August 1982 35 All active components for the linear/exponential controls are located on chip. Discrete com­ ponents may offer improved accur­ Component Profile: acy, but the 0.05% typical, 0.2% maximum exponential error is more than adequate for reliable poly­ phonic performance. A solid-state SSM 2 0 3 3 heater/sensor combination for tem­ perature compensation keeps drift to a maximum of +_ 100 ppm/ocenti- and grade. Referring to fig. 1, resistor ratios (R2 + Tl)/R3 and R22/(R23 + S S M 2 0 4 4 R24) establish one Volt per octave tuning. The ratio of R23/R24 sets high frequency tracking, where R23 + R24 must equal Ik. Thus, a lk by: Tom Helf rich trimpot, T3, may substitute for R23 + R24. If frequencies above 5 kHz are not needed (which is often While several manufacturers The SSM2033. The SSM2033 is make ICs suitable for electronic a sawtooth based oscillator with the case), you may replace R24 music, there are only two compan­ hard and soft sync capabilities, with a jumper and make R23 equal to lk. The remaining trimpot, T2, ies specializing in the field, triangle converter, pulse width trims out frequency offsets of Solid State Music and Curtis Elec­ comparator, and full linear/expo- multiple oscillators when using tromusic Specialties. This arti­ nential converter. Requiring only several SSM2033s in polyphonic cle will examine two relatively passive components, all inputs new chips from SSM, the SSM2044 accept industry standard voltages applications. dedicated low pass filter and and present standard impedance Since the SSM2033 derives its negative voltage from an on chip SSM2033 temperature compensated levels. Outputs are short circuit VCO. protected. Zener regulating diode, its out-

36 POUPHONU M ay - August 1982 puts are clamped to about zero Referring to fig. 2, scaling the resonant frequency of the Volts on negative transitions. resistors Rl/R3a and R2/R3b allow filter, feed the control voltage External circuitry has been pro­ the differential signal inputs to into VC-1 and ground R9c or R9d. vided to level shift and amplify accept input levels up to the Since pin 2 of IC2a is a summing these signals to _+ 5V standards. power supply limits. If using two junction, adding more 100k resis­ Thus, IC2a outputs a + 5V trian­ oscillators in a voice, the output tors to this point allows multiple gle. of one voice should go to one control voltage mixing. For a IC3 smoothes this triangle input, and the output of the sec­ response where negative control into a sine wave, buffered by ond voice should go to the oppo­ voltages decrease the resonant IC2b. To optimize sine wave char­ site input with a 3 dB level dif­ frequency of the filter, feed the acteristics, observe the sine sym­ ference (values shown assume this control voltage into VC-2. This metry at IC2b's output while test­ type of application). Filter tun­ stage can also accommodate both ing the assembled module. If the ing capacitors Cl - C4 should be positive and negative going con­ positive peak is more rounded, 1% tolerance, low temperature co­ trol voltages by feeding them into connect R19 to -15V; if the nega­ efficient parts for best results VC-1 and VC-2 respectively. tive peak is more rounded, connect and precise response. IC2b along Scaling resistors R9/(R7 + R19 to +15V. Use a potentiometer with R10 and C5 convert the output T2) and-R5/R6 give a lV/octave to determine the optimum value for current to a voltage. response, where R6 may be selected R19. After establishing correct On the evaluation boards for a +3600 ppm/oc response if symmetry, adjust for lowest dis­ manufactured by Global, op amp extreme temperature stability is tortion by selecting R17 in the IC2a provides for differential required. range of 50k to 100k. summing. There are provisions for Since the on-chip resonance Sawtooth-1 is a 0 to 10V up to eight CV input resistors, control has a reverse audio res­ output; IC4b converts this to a + which terminate in one PC board ponse, a CA3080 was selected to 5V standard. IC4a's output is a trace that bridges pins 2 and 3 of sum the resonance control voltages jtl2.5V pulse whose width may be IC2. This trace may be broken and approximate the proper taper varied from 0% to 100% by voltages anywhere along its length to split for electronic music applications. applied to R29 (PWM-2). the eight resistors between the Maximum attainable resonance is The SSM2033's main pulse out­ inverting and non-inverting inputs set by Rll, and break-point for put has been purposely inverted by of IC2a. The circled x between the non-linear function is set by Q1 for the following reasons. IC2a pins 2 and 3 represents where R14/R13. Note also that IC3 is Note that the hard and soft sync you would break the trace. set up in a manner similar to inputs trigger on falling edges. To configure this stage so IC2a, and can accept both positive The falling pulse edge observed at that a positive voltage increases and negative going control volt- pin 8 is fixed to the discharge of the sawtooth, while the leading pulse edge varies with the PWM-1 control. If the pulse is inverted and applied to the sync input of another VCO, then the oscillators will be frequency locked at a phase angle determined by the PWM- 1 control voltage. Thus, PWM-1 may be considered to be a voltage controlled phase shifter in a mu11i-osci11 ator voice. This might also be useful in an LFO system employed in location modu­ lators . The SSM2044. Unlike the SSM2040 and CEM3320 (filter ICs which allow a variety of complex responses), the 2044 is a dedi­ cated 24 dB/octave low pass fil­ ter. Its accuracy, low parts count, and ease of application should attract many musicians in­ terested in developing their own performance systems. Filter input signals are accepted and processed differentially, canceling some offset and linearity errors. The on-chip resonance circuitry also uses differential techniques. Output signals are quiet, "pop- free", and stable within the audio spectrum. Applications include electronic music low pass filters, tracking filters for analog delay lines, stable sine wave genera­ tion, and the like.

nouPHONy M ay - August 1982 37 ages; again, the input resistors R12, R13, connect to one trace which may be R26, R27, SSM2044 Low Pass Filter broken to assign different resis­ R29 100k tors to IC3's two inputs. R14, R28 300k RI 68k Optional "Q rejection" and RI 5 200k R2, R14 100k initial frequency trims are avail­ R16 47k R3a, b 200 Ohms able as T1 and T3 respectively. R17 62k R4 470k Evaluation boards available. R18a., b lk R5 150k* Global offers experimenter's/- R19 see text R6 lk* evaluation boards for the SSM2044 R20 220k R7 270k* and SSM2033 for $6 each ($5.25 R21 39k R8 150k* each in quantities of 10-up). The R22 54.9k* R9 100k* SSM2033 IC itself is available for R23 lk; see text R10 47k $10, the SSM2044 for $5.75. Terms R24 see text RI 1 56k are $2 shipping/handling on all R25 36k R12 22k orders, and 6% sales tax for Penn­ R30 15k R13 lk sylvania residents. Address all R31 4.7k inquiries and orders to Global, Cl 820 pF* 541 East Market St., Marietta, PA Cl, C5, C2-C4 0.01 uF* 17547. C6 1000 pF C5 15 pF C2, C3 0.1 uF C4 300 pF T 1 50k trimpot Parts List C7 0.22 uF T2 50k trimpot* T3 50k trimpot SSM2033 Oscillator T 1 20k trimpot T2 100k trimpot IC1 SSM2044 RI 620 Ohms T3 lk trimpot IC2 TL072 R2, R3 100k* IC3 CA3080 R4 470k* IC1 SSM2033 R5 3.3k* IC2, IC4 TL072 R6 3.01M* IC3 CA3080 *1%, low tempco for bes stability R7 47 Ohms Q1 2N3904 R8 1.5M R9 27k RIO., RI 1 22k ELVIS—ALIVE? READ THIS STARTLING BOOK THAT RAISES QUESTIONS THAT MUST BE ANSWERED. CLUES ELVIS LEFT THAT UNDERSCORE THE FACT “ELVIS” MIGHT STILL BE ALIVE. DID ELVIS FAKE HIS OWN DEATH?

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38 POUPHONy May - August 1982 f c y IW TO TTft Dennis Bohn BASIC TRAINING

Back to basics. not available to you and you happen to know, or can The gain of the inverting amp shown in fig. 1A find out, the unity gain frequency of the device, is -R1/R2. Big deal! Okay, I never promised a lot then you can use this information to calculate the of excitement, but, what is the gain from point 1 to open loop gain at any frequency. This is the con­ the output? And what is the input resistance at cept of Gain Bandwidth Product (GBW) and is most point 1? And the output resistance of the ampli­ useful. The unity gain frequency of any op amp is fier? the frequency where the open loop frequency response The answers that will get you into trouble are is unity (how's that for double talk?). The GBW is "one", "zero", and "zero", respectively. therefore this same number, since it is the produce How about figure IB? What is the input resis­ of one times this frequency. For example, an LF351 tance at point 1? And the output resistance? has a unity gain frequency response equal to 4 MHz, To answer these questions, we need to back up a hence, GBW = 4 MHz. Now, to find out how much open bit and review the concept of "loop gain". Loop loop gain there is at, say, 10 kHz, all you do is gain is the difference between the closed loop ivide the GBW by 10 kHz. The answer is 400 V/V or (feedback in place) gain of a circuit and the open 52 dB; therefore, an LF351 has an open loop gain of loop (no feedback) gain expressed in dB. For exam­ 52 dB at 10 kHz. And operated at a closed loop gain ple, a circuit with a closed loop gain of 20 dB and of, say, 20 dB (times 10) then it has a loop gain, an open loop gain of 80 dB has a loop gain of 60 dB. T, equal to 32 dB (52 dB - 20 dB = 32 dB). This, Loop gain is commonly given the symbol T, and it is then, is how much "stuff" is available to fix dis­ the magic stuff which makes feedback amplifiers a tortion, impedances, etc. wonderment. Now, back to the original questions: The gain It is loop gain that reduces distortion and from point 1 to the output for the inverting con­ output impedance and either increases or decreases figuration of fig. 1A is the available open loop input impedance. Loop gain is the glue which keeps gain at the frequency of interest. If not totally feedback amplifiers from coming apart when hit by understood, this can come as a big shock in using complex audio waveforms. And it is loop gain, or inverting amplifiers. Even though the closed loop rather, lack of loop gain, that will sneak up and gain from Vi to Vo may be unity, the gain from the bite you on the ankle just when you think that your input pins is always whatever open loop gain is circuit is working perfectly. available, times the differential voltage present The problem comes about from the frequency between the plus and minus inputs. dependent nature of loop gain, i.e., it is not A practical example of where this can be a real constant over frequency; it falls off at a 6 dB/oc- problem is in mixer designs. Point 1 becomes the tave (20 dB/decade) rate for well designed, stable main summing node for all of the mixer inputs and op amps. Each type of op amp has a different open because of the real world truths of mixers, it is loop characteristic and the data sheet must be con­ generally a long piece of bus wire strung between sulted in order to know how much loop gain is avail­ each input module, sometimes reaching a length of able for a particular frequency. If a data sheet is several feet! Now, anything unwanted induced into

rourHONy M a y - August 1982 39 this node (hum, spikes, noise, RFI, etc.) gets am­ very complex subject, and is not well behaved at plified by the open loop gain...which is why many all. Rarely does it follow a nice 6 dB/octave designers pull their (already gray) hair out in curve, but is usually stays low enough at all gains trying to produce really quiet mixing nodes. and frequencies so as not to be a problem. If So, how can you ever live with this char­ output impedance is of critical interest to your acteristic? This brings us to the second question circuit's behavior, then the exact data sheet must of what the input impedance is at point 1. It is be consulted very carefully.) very low, but it is not zero, and it is frequency Our last unanswered question concerns the input dependent. For practical purposes, ijt .is the feed­ impedance of point 1 of the non-inverting configura­ back resistor, RI, divided by the open loop gain, T. tion of fig. IB: It is resistor R3 in parallel with So at DC, it can be very low, but it rises at the the input impedance of the op amp. The input imped­ same 6 dB/octave that the open loop response falls ance of the op amp is the open loop input impedance off. Back to our example of the LF351 operating times 1 + T. So, it starts out very large and drops with a closed loop gain of 20 dB: Assume RI equals at the 6 dB/octave rate. For Bi-Fet op amps such as 100k Ohms, then the input impedance at 100 kHz is the LF351, it never drops to a level of real concern 100k Ohms divided by T. T for 100 Hz equals a unless you are using extremely large values for R3 factor of 4000 (72 dB), so the input impedance is 25 (like 10 MegOhms, for instance). However, for bi­ Ohms - not a big problem. But, at 10 kHz this polar input op amps, like the super quiet NE5534, impedance rises to 2500 Ohms, since T is now only 40 you must keep an eye on things, or surprises may be (32 dB) - a much bigger problem. And if RI was in order - particularly at higher gains. The open large, say 1 Meg, then the impedance at 10 kHz would loop input impedance of an NE5534 is only 100k Ohms equal 25k Ohms - definitely a problem! Of course, (typically, guaranteed is only 30k!) compared to going the other way can save your bacon. Let RI = 10^2 Ohms for Bi-Fets. So, for closed loop gains of 10k Ohms, then the impedance at 10 kHz is only 250 40 dB, the input impedance at 100 Hz is 100 Meg, but Ohms. drops to 1-Meg at 10 kHz. What about output impedance? For both config­ Figure 2 gives a summary of feedback amplifier urations of fig. 1, ij: ijs the open loop output parameters and how they affect certain operating impedance divided by + T. So again, it is very characteristics. Figure 3 compares three popular op low, but has a rising frequency dependent character­ amps for your reference. istic. For the LF351 it starts out at around 20 There, you ate your spinach. Now you may have milliOhms for 100 Hz and rises to about 2 Ohms at 10 dessert! kHz. (Output impedance of op amps turns out to be a

— | | s i M g i i S ■MM — ( j fi HI Fig.2 Summary of Feedback Amplifier Parameters

Amplifier Input Output Harmonic Noise Bandwidth Type Impedance Impedance Distortion Gain (closed-loop I

Ro THD A VCL GBW Non - Invert ing 11 + T I Rin 1 + T 1 + T a v c l

Rf Ro THD A VCL+ 1 GBW Inverting T 1 + T 1 + T A V C L+ 1

Av c l : closed- loop gain R0 :open-loop output impedance ' GBW :gain bandwidth product; unity-gain frequency T : loop gain Rf : feedback resistor THD : open-loop total harmonic distortion I % I Rj„ : open-loop differential input impedance

' : Fig. 3 I! Op Amp Comparison

Voltage Gain idBI Input Output i4 5l Loop Gain Rin l5 '6 ' Rout !5i Device DC 10kHz Res lohm sl Res lohm sl 11 + T , V / V I (closed I (closed!

5534 l3! 100 67 100 22 72 7.2 0.3

LF351 100 52 1012 75 14 14 X t 0 t2 5.4

i0 12 TL071 106 50 200 11 11 X 10 12 18

N otes: 4. See te xt. 1 Commercial grade, plastic pkg, TA -25° 5. Closed loop gain * 30dB . Frequency = 10 kHz 2 All data is open loop and typical values unless otherwise specified. 6. Op Amp input resistance; in parallel with network resistor effects. 3. Compensated for unity gain (22 pF)

40 POUPHONU M a y - August 1982 Remote Switching for DOD 500 Series Processors

By: David Di Francesco, DOD ELECTRONICS CO.

Remote switching is useful in Figure 1 shows the circuitry That's all there is to adding several applications. One is located on the switch board, which remote operation. But while we're pedalboard systems, where you is underneath the main circuit at it, here's one more tip for 500 might want to have the effect at board. You can add J1 by drilling Series devices: if you already arm level (for ease of adjusting a hole opposite the LED position have a DOD 200 power supply, you the controls) while having the on the side of the chassis, and can use it to power several 500 status footswitch located on the run a wire from the tip of the Series effects by simply the re­ floor. Another is for electronic jack to the junction of SI and RI placing the DOD 200's LM78L10 switching systems, where you might on the switch circuit board. regulator with an LM78L15 regula­ want to control an effect's status tor with logic signals. added wire It's easy to add remote switching to all DOD 500 series products, since each one uses a momentary, normally open switch to change the status of the effect. Simply putting another momentary switch in parallel with this ori­ ginal switch gives remote opera­ tion. Because the footswitch only switches a DC control line, there are no hum problems with adding the remote switch.

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SPST (on/on) Mini-Toggle IC Sockets (soldertail) We also have CMOS, books, jacks, plugs, LED’s, & More!- Send For Our Flyer! Switch (3 amp) $1.20 (High quality tin wipe) TERMS: CHECK, MONEY ORDER, MASTERCARD, VISA. No minimum on check or money orders, but if less than $10, ADD .75 PROCESSING CHARGE. 10 K pot (linear).....$1.09 8 pin - .27 14 pin - .30 $10 MINIMUM on charge orders (Mastercard and Visa). Give card number and exp dale Indiana residents add state sales tax 16 pin • .34 28 pin - .60 SHIPPING and Handling: $1,00 plus 5% ot purchase. We will credit any amount over our standard rate. 10 K pot (log)...... $1.09 10 K pot w / switch Transistor 2N3906 - .25 SATISFACTION GUARANTEED! MONEY BACK IF NOT SATISFIED! Prices and availability subiecl to change wilhout notice Not responsible for typos. (audio taper)...... $1.25 24 Hr Order/Message Phone Diodes 1N914 - 5/.35 250 ohm trim pot...... 40 M0REI-GET FLIER! 812 894-2839 JO K ohm trim pot...... 40

POUPHONU A lay - August 1982 41 EOUIPfTEnT EXCHflOGG

PUT POLYPHONY TO WORK FOR YOU. List equipment for sale or trade, job openings, positions wanted etc. Equipment exchange classified rates for individuals offering goods or services for sale or trade: 25c per word, 20 word ($5.00) minimum charge; Commercial establishments: 50c per work. Prices, zip, phone numbers count as one word each. DISPLAY CLASSIFIED; $15.00/inch, one inch minimum, camera ready art to be supplied by advertiser. All classified advertising must be prepaid. Advertisers using a Post Office Box for responses must furnish Polyphony Publishing Co. with a complete street address and phone number. Readers should respond directly^ to advertiser. Polyphony is not responsible for claims made in ads, or the result of any transactions. Polyphony reserves the right to edit or refuse any ads submitted.

ROLAND JUPITER 4 Poly synth very good condition with Anvil case, music equipment used mainly in studio $1400. (213) W a n te d 652-6964. PROPHET 10 Synthesizer with We want to hear your original sequencer, stand, Anvil Case. FOR SALE: 4700/S Assembled and copyrighted electronic music for $6500. Douglas Desander, 234 working, plus 2-4761 cabinets, our upcoming nationally syndicated Beechwood Ave., Norfolk, VA 23505 4720 VCO, 4730 VCF, 2-pre-amps, radio program. This program has a Phone (804) 423-7491. 2720-7 power supply, front cover, way for listeners to order your and Synthespin MK-II. $500 plus cassettes or records through a shipping, or best offer. A. toll free number. To submit or PAIA 4700/S including D/A, 2720-11 for information, write Creative envelope follower, patch cords, Stahley, 8 Donovan Dr., Coplay, PA 18037 (215) 261-0176. Call after Rediffusions, 7019 Big Daddy Dr., all manuals. Must Sell. $350 or Panama City Beach, FL 32407. offer. Jeff Jacobsen. Box 64, 5:30 PM EST. Logan, Utah, 84321 (801) 752-8819

POLYFUSION SERIES 2000 Modular Synth.- 2 VCO, 4 Mixers, 4 octave R ecordings Recording equip. keyboard, LFO, Filters, Full warranty, More. $4320 List BEACON STAR - Ken Moore calls it PIONEER RT-2044, 10-1/2 inch reel $1800 or best offer. Call or "Enchanting and not without a to reel with sync. 1/4 track head write for further info. Michael touch of science fiction stack, 1/2 track head stack, Krewitsky, 3089 54th St. San appreshension." Chris Meyer service manual, cables, tapes, Diego, Ca 92105 (714) 583-7851. describes it as "both mystical road cases, shipped in original and reassuring, open spaced and cartons. Pro deck - $875. Dale, 5263 Skeeswood Drive, Salt Lake COMPLETE PAIA P4700/J complete, interesting and Computer-Controlled Synthesizer beautiful." Beacon star is City, UT 84118 (801) 967-0419. system. Factory calibrated. synthesizer/space music on Includes all manuals and cables, cassette tape. $5.00 postpaid cassette programs. ( $500. SOUND check or money order only to CITY electronic piano with Bass, Chuck Larrieu, Box 294, Corte P a rt/ Harpsicord and split keyboard. Madera, CA 94925. Includes sustain footswitch, case SSM 2030 VCO, 2040 VCF chips. 100% and stand. $350. Rick Cohen, 15 rime. Originally $10 each, now BILL RHODES and EVERFRIENDS "Key 2.50 each or 5 for $10. Add 60c Bechstein Dr., Matawan, NJ 07747 Essentials" album on cassette. (201) 566-6664. for shipping, spec sheets. ERSKINE Features Pipe organ, Korg Poly SIZERS, P. 0. Box 2671, Houston, Six, and Trident Synthi, also two TX 77252. PAIA P-4700/J soon to be released movie Computer/Synthesizer; 4782 Road soundtrack excerpts. $5.00 from keyboard with glide; EK-2 Computer Jazzical Records, 845 #2 Drums. Professionally assembled. Foresteria Dr., Lake park, FL Softuuore 33403. Asking $650. Mark Augustine, 1823 E. Kenmore PI. Shorewood, WI 53211 SELL OR TRADE 8700 software: ELECTRONIC MUSIC, Dreams and Polychorus offers both MUSI POLY (414) 962-8991 Evenings. Nightmares, a C-90 Dolby Cass. By and Polychorus type assignment J. P. Lamar. Diverse selections to algorithms with STGs in either stretch your mind. $7.50 check or mode and more. Relayer is a E-MU 4060, 16 voice microprocessor M.O. , JPL Sound Box 215, polyphonic synthesizer controller monophonic entry, polyphonic Caldwell, NJ 07006. playback, four voice layering with 2000 note memory and custom sequencer, requires memory to software - $3500. Dave Bradley, $07FF. For complete list send SASE 5111 Colerain #2, Cincinnati, OH to Jack Deckard, 1877 Tamarack 45223, (513) 541-7290. R e r/o n a l/ Circle S Apt. C, Columbus, OH 43229.

P-4700/J SYNTHESIZER - New, Looking for Hobby Electron. completely assembled only some Musician/Recordist (anywhere) to Help wanted bugs with D/A converter. $800, or exchange tapes, ideas and musical will take best offer received in concepts with. Write: Rick ADVERTISING SALES POSITION - Part next 30 days after ad breaks. Joe Burgmeier, 103 Brookline Rd., Montesi, P. o. Box 11057, Memphis, Syracuse, New York 13208 time. Commission & expenses. TN 38111 (901) 683-4991, evenings. Contact Polyphony Managing Editor (405) 842-5480.

42 POUPHONy — M ay - August 1982 # 252 Memory System Give Your Analog Synthesizer New Life With Precise Digital Control

Instantly set your pitches, filters or any other voltage controlled Junctions.

The 252 Memory System is designed to provide in­ stant presetting of music synthesizers. It will dramatically increase the usefulness o f your modular (or custom) music system by turning it into a program­ mable system with performance capabilities. There are 32 independent control voltage outputs and 32 presets o f these 32 voltages (expandable to 64 presets). These outputs are user programmable and ac­ curately repeatable for pitch grade applications. The user may write his programs in groups of 4 voltages at a time or singly address any one parameter. Memory is retained without power being applied by a self-contained user-replacable battery. Advance and reset jacks are provided to enable counting through the resets with an external clock source. Many systems may not have all voltage-controlled functions so some auxiliary modules may be required. For example, to implement programming of an LFO mod depth a VC A would be required between the LFO output and the input to be modulated (VCA cv in would come from the programmer and thus control the depth o f modulation). The 215 Quad VCA and 256 VC Dual ADSR’s are well suited for use with the 252 Memory System. Vz ACTUAL SIZE

SPECIFICATIONS

Outputs: 32 control voltage outputs, fully buffered Advance: Counts 1-16 only, will not count through for systems use, output range is ±5.3V (0 - 10 available bank 1/2. at higher cost, but is usually not necessary), quantiza­ Power Requirements: Either ±18 or ±15V(specify if tion level is .041V or M step resolution over 10 octaves you are supplying power, ± 18 is to power optional on- at lV/oct. module regulators) AND ±12(nominal) unregulated.

P.O. Box 40267 San Francisco Ca., 94140 Tel (415) 824-4837 East Coast Office: 8 Tyler, Norwell Ma., 02061 (617) 659-2618 HOW DO I INSTALL IT Installation of the transducer is surprisingly Veloci-Touch' straight forward. In most cases it is simply a matter of removing or loosening the screws that hold down the front edge of the keyboard, slipping the bender Controller under the frame and re-tightening the screws. Both stand-alone and modular packaging is available for the electronics. The 8786 package il­ lustrated includes a line-operated power supply, trim contemporary case and provides standard V4" jacks for control voltage outputs. Also available is the 4786 configuration which is mechanically and electrically consistent with PAIA 4700 series modular equipment. In some instances, the front panel supplied with the 4786 may be used as a bezel or discarded and the 4" x 4V2 " circuit board containing the Veloci-Touch processing electronics mounted inside the instru­ ment with the ± 9v. to ±15v. power required by the V-T tapped from the keyboard’s own supply.

CAN I USE IT WITH MY (your axe here) One of the most over-worked lines in advertising is “ limited only by your imagination” . It should come as no surprise that it is most often used when the person writing the copy has no idea how you use it. WHAT DOES IT DO In this case, though, it may be a valid observation The new Veloci-Touch controller from PAIA adds because while the V-T’s uses with synthesizer ar fair­ what may be the two most important parameters that ly obvious, many people will find creative ways to any electronic keyboard can have — velocity and se­ use it with combo organs, electric pianos and other cond touch pressure sensitivity. instruments. Even when an instrument already has Velocity is a control voltage proportional to how velocity sensitivity capabilities, second touch for hard you play. Pianissimo and the voltage is low. For­ tremolo or vibrato can be very handy. tissimo and it’s high. Use this parameter with a VCA and presto . .. output level changes that follow your ARE THERE ANY “YEAH....BUT’s” playing. Not really, but remember that you are installing But, since “ loud” and “ soft” mean more in human the V-T equipment to produce a more expressive in­ terms than just level changes, the Veloci-Touch con­ strument and this implies the development of a troller also prpvides a velocity sensitive transient technique that realizes that potential. While you can generator with variable decay time and an output get really extraordinary “ effects” the first time play a control that’s continuously variable from normal to V-T’d keyboard, the technique required for real con­ inverted transients. Use as a filter parameter control trol only comes with practice. for the most natural timbral changes ever. For example, it is more difficult than you would Even that’s not all. The Veloci-Touch controller first guess using the second touch pressure for also provides an output proportional to the pressure pitch bends that precisely hold a note, partially you apply to the key after it’s down (second touch). because the controller circuitry does not hold a con­ Imagine — tremolo the natural way. stant output for constant pressure but rather decays The best part of this minor miracle from PAIA is away with time. But with a little practice you quickly that it’s non-denominational. You can retro-fit it to develop a feel for how much you must increase essentially any synthesizer from any manufacturer. pressure to hold a bend. For most, a little construc­ HOW DOES IT WORK tive play will yield extremely gratifying results. The secret of the Veloci-Touch controller is a thin No. 8786 VELOCI-TOUCHtm CONTROLLER KIT piezo-electric transducer (called a bender) which (Shown in photograph)...... $69.95...3 lbs. slips under the keyboard and in effect “ listens” to how hard you play and how much second touch No. 4786 VELOCI-TOUCHtm CONTROLLER MODULE pressure you apply. The electronic processing of the KIT (PAIA 4700 Series Compatible). . . . $44.95...1 lb. controller uses the synthesizer’s gate signal and INSTRUCTION MANUAL ONLY $5.00 postpaid other cues to separate the velocity transient from (REFUNDABLE WITH KIT PURCHASE I the second touch pressure and provides indepen­ dent outputs for both. ORDER TOLL FREE WITH VISA OR MASTERCARD IS IT POLYPHONIC The Veloci-Touch controller does not provide an 1-800-654-8657 individual output for each key in a polyphonic 9AM & 5 PM CST MONDAY THRU FRIDAY system, but is still useful in this application. Even a DIRECT INQUIRIES TO single output for velocity and pressure is a major im­ provement over no touch sensitivity at all. BKA Electronics, Inc. 1020 W. Wilshire Blvd., Oklahoma City, OK 73116 - (405)843-9626