P M i o a y $2 50 ELECTRONICS-MUSIC-HOME RECORDING A p ril 1983

i m m m

HH MOTION FILTER B & iA STOMP BOX EFFECTS An envelope follower/filter combination translates the normal dynamic properties of your axe into modulated timbral AT LOWER THAN 1980 PRICES changes as well, the effect is like a wah-wah pedal being used These new stomp boxes from PAIA are designed to give elec­ by someone with magic feet. The first time you get your tronic guitarists the highest quality effect at the lowest possible MOTION FILTER working you won’t believe that so much funk price. Cases are formed of heavy steel and covered with the and soul can be squeezed into such a tiny box. most scuff-resistant baked-on finish available. All feature Independent Initial Frequency and Sensitivity knobs give heavy duty switches for long life and electronic effect switching you the control you need to realize a wide range of effects for pop-free punch-in and punch-out. All are high input and allow the MOTION FILTER to be used with either electric impedance, low output impedance, non-inverting, low noise bass or guitar. No. 5720 MOTION Filter Kit.. $29.95 (3 lbs.) devices designed to meet all proposed FX standards. Each provides hour after hour of operation from a single 9 volt GATOR™ Noise Gate/Envelope Controller battery and provide automatic power switching; you'll never The almost un-noticeable “hiss or swish" that each unit have to worry about forgetting to turn them off. in a multiple-effects system adds to your music can sum to annoyingly noticeable background noise just when things HOT LYX SUSTAIN are supposed to be quiet. GATOR listens while you play, and when you stop, electronically isolates your effects from your Probably the most used effect by any electronic guitarist, amplifier, zapping noise completely. a sustain unit is essentially an amplifier that automatically And despite its low cost, GATOR has added features that increases its gain to compensate for a guitar’s normal decay let you do more than just make other effects sound good. characteristics. The result is the ability to hold notes and chords It's an important effect in its own right. much longer than would otherwise be possible. The ATTACK control lets you re-shape the normal percussive Hot Lyx gives you all the control you need, continuously envelope of your guitar for bowed string and organ effects variable sustain from just enough to make your Silvertone with attack times up to 1.5 sec. and an AUXILIARY TRIGGER sound like a Les Paul to “pedal to the metal” controlled feed-back settings that give rock-guitar its “all-out” quality. SIGNAL INPUT allows the dynamics of one instrument to be gated by another (drums, for example) to impart unique Level control allows for either lower or higher volume levels “synchro sonic” rhythmic characteristics to your sound. when you’re punched into the effect and can also be used as Other features include High Impedance In/Low Impedance an over-drive control to give you the sweetest fuzz/sustain Out, Electronic Footswitch for quiet punch in/out, wide range sounds you’ve ever heard. Threshold Control, Single 9v. battery supply (not included). No. 5710 HOT LYX Sustain...... $34.95 (3 lbs.) GATOR (tm) Cat. No. 5730...... $34.95...... 3 lbs. MIDRANGER™ Midrange Equalizer Sure, your amp has bass and treble controls — but what about the all important midrange? When you need more sound from your axe than most amps can give, but don't have the bucks for a fancy equalizer, the MID-RANGER is for you. Featured in Craig Anderton's June 1982 Guitar Player column, this special purpose equalizer gives more presence and “punch” by providing continuously variable boosts of up to 12 db. at switch selectable frequencies of 90, 200, 1000, 2000 or 4000 Hz. Designed for guitars, voice, rhythm boxes and keyboards, the MIDRANGER features High Input/Low Output Impedance, quiet electronic switching and single 9v. battery supply (not included). MIDRANGER (tm) Cat. No. 5740...... $32.95...... 3 lbs. 5750 — AXE GRINDER(tm) A classic fuzz to FX standards. The AXE GRINDER might be a pretty routine fuzz if it weren't for a couple of subtle but significant features. Like a Distortion Intensity Knob that provides smooth control of clipping from just a hint when you really get it on to pure square waves when you even think of picking. And the Distortion Tone, Distortion Level, and Clean Level controls are like having a built in mixer and E.Q., letting you precisely set the amount of distortion and its tone as well as the mix of clean and distorted signal. You probably never realized you could get so many sounds from a “simple” fuzz. The AXE-GRINDER also features totally pop-free electronic switching and adherence to uniform FX standards that allow any Effect to work with any other without concern for mismatch noises or phase incoherence. 9 volt battery power (not supplied). 5750 Axe Grinder(tm) Kit. . . $29.95...... 3 lbs. 5760 ROCKTAVE DIVIDER(tm) Whereas most effects that alter the harmonic content of a signal can only produce or accentuate frequencies higher than the fundamental frequency produced by the instrument, the ROCKTAVE DIVIDER fills out your sound by adding in wave­ forms that are sub-harmonics of those produced by your axe. Compandor stages are used to stabilize input for reliable triggering of the divider circuitry and to impress the original dynamics of your playing onto the newly created subharmonics. Independent level controls on the extracted fundamental and first and second sub-octaves allow you to produce just the mix you're after and master tone control lets you round the square wave sub-octaves off to near-sinusoidal purity. QUALITY The ROCKTAVE DIVIDER also features automatic power switching when in use, pop-free electronic cancel function EFFECTS and single 9 volt battery power source (battery not supplied). 5760 Rocktave Divider(tm)...... $39.95...... 3 lbs. AFFORDABLE ORDER TOLL FREE WITH VISA OR MASTERCARD PRICES 1- 8 0 0 - 654-8657 DIRECT MAIL ORDERS & INQUIRIES TO:

IB iA E lectronics, Inc. 1020 W. W ilshire , Oklahoma City, OK 73116 - (405)843-9626 STAFF ISSN: 0163-4534

PUBLISHER Polyphony John S. Simonton, Jr. VOLUME 8, NUMBER 3 EDITOR APRIL, 1983 Craig Anderton

MANAGING EDITOR Linda Kay Brumfield

TECHNICAL ILLLUSTRATOR Caroline Wood Build A Bass Pedal System ...... 17 CIRCULATION By: Stefan Hawk Ramona French Peggy Walker Dr. Rhythm Modification ...... 29 By: Craig Anderton BOOKEEPING Cathi Boggs Meet SID Sound Interface Device ...... 33 PRINT PRODUCTION By: James Lisowski Phuong Nguyen SEMCO Color Press Switched Capacitance/Transversal Filters ...... 12 By: George Quiroga POLYPHONY (ISSN 0163-4534) is published bimonthly at 1020 W. Wilshire Blvd., The Rockman Cometh! ...... 10 Oklahoma City, OK 73116, by Polyphony By: Kirk Austin Publishing Co. Entire contents copyright (c) 1982 by Polyphony Publishing Co. All rights reserved. No portion of this Voltage Controlled LFO ...... 36 publication may be reproduced in any By: Craig Anderton , manner without written permission frpm the publisher. Second Class postage is paid at Oklahoma City, OK 73125. Voyetra Eight Review ...... 8 „ By: Mark Styles ADVERTISING rate card and deadline schedule is available upon request. Contact Linda Brumfield at (405) Sources in Acoustics ...... 30 842-5480. By: David Doty DEALERS & DISTRIBUTORS bulk prices are available upon request. Contact Linda Brumfield at (405) 842-5480. SUBSCRIPTION rates: American 1 year $12.00 2 years $22.00 Foreign 1 year $14.00 2 years $26.00 DETAILS: The Audio Connection We now accept MasterCharge and Visa by: Dennis Bohn ...... 16 payment for subscriptions, back issues, and PolyMart items. Foreign payments must be by charge card, money order, or PRACTICAL CIRCUITRY: Transistor Circuits certified check in US funds drawn on a by: Thomas Henry...... 26 US bank. BACK ISSUES are available at $2.50 each Re-View: ppd. Send SASE and request our 'Back by: Robert Carlberg 6 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 code, and any numbers from the mailing label, as well as your new address. When you move, be sure to notify your post office that you DO want second Ad Index...... 38 class and controlled circulation ublications forwarded. This will save Current Events ...... 23 ?ost or returned issues. Polyphony is not responsible for replacement of lost or returned issues when we have not been Equipment Exchange ...... 38 supplied with change of address information. Letters ...... 4 TO POSTMASTER, send address changes to: POLYPHONY PO Box 20305 Oklahoma City, OK 73156 COVER PHOTOGRAPHY BY: Vesta Copestakes, CAVE Grafix HE Ph. (405) 842-5480

Polyphony A p ril 1983 3 WIND PLAYERS

You can use your own instrument or voice to control any standard synthesizer, with more expressiveness than a keyboard. modular synthesizer is an extreme- ly cost-effective system which CALLING ALL SYNTHS v5 <3 O O O ° allows experimenters to make <30 0 0 0 ® sounds they would never be able to I have been evaluating vari­ otherwise afford. It is also a V s M A M k I 1 ous synthesizer kits for about two quite versatile system (see David THE GENTLgELECTRIC years, and finally decided on the Vosh's letter below). I use PAIA PITCH AND ENVELOPE:, RMS ARIES. I estimate it will keyboards myself, but overall I FOLtm/ER take me two to three years and would say the 4700 series equip­ about $4,000 to complete the sys­ 1 n r - ment is not quite as sophisticated p A Y tem. as what you appear to be contem­ Write for our free detailed Recently, I called RMS and plating. brochu rep patch diagrams, unfortunately found out that no From the tone of your letter, I p new development is being done on and application notes. I feel you will be most satisfied the ARIES line and that all- orders by a synthesizer that you build P A 1 for ARIES modules are considered Also available as modules for Aries and yourself. It's not that hard, custom orders. I wonder if RMS Serge synthesizers, o r as Circuit boards especially if you take it one fo r cu sto m systems: Deckers Inquiries y will offer ARIES modules for the module at a time. The PAIA EKx " ’ W e lc o m e , next three months, let alone three series kits are excellent for years. I've noticed that RMS has providing the basic VC0-VCF-VCA- not advertised in Polyphony for qentle electric VCEG functions, .CES and SSM offer L s Dept P quite some time now, is that some evaluation boards for their music P .0 Box 132, Delta, CO 81416 indication of their stance in the (303) 374-7171 chips, and of course, both Poly­ synthesizer business^? phony and Electronotes (1 Pheasant I'm looking for alternatives. Lane, Ithaca, NY 14850) have I never gave PAIA modules much ELECTRONIC PROJECTS published many synthesizer cir­ consideration, I am ashamed to cuits (check out some of Thomas FOR MUSICIANS admit, because they don't seem to Henry's modules in recent issues, have that "professional" look that Project kits now available for example — they're pro-spec ARIES has. If you can give me a exclusively from RAiA and and inexpensive), as well as the good pep talk on the qualities of for a limited time at a special Barry Klein book advertised in a PAIA system, I'd really appre­ Polymart. Really, doing it your­ *10% off sale price Regular Sale ciate . Proj # Title Price Price self isn't that much harder than 1 Preamp (less XLR and VU) ^22.951 $20.65 building from a kit, and you'll 2 M etronom e 9.95/ $17.94 Allen Hoeltje end up with a synth which fits 3 Passive Tone Control $16,951 $15.25 Boulder, CO your needs exactly. 4 Headphone Amp. $ te.9 3 $17.95 5 M ini-A m p $29.9$ $26.95 So there's your pep talk. 6 Ultra-Fuzz $19.95 $17.95 Allan — Ah yes, we certainly Warm up your soldering iron and go Bass-Fuzz $21)95 $19.65 7 handle the tough questions around to it! 8 Compressor/Li miter $ 2 7 |5 $25.25 here! The Aries is more or less a 9 Ring Modulator $29,15 $26.95 10 Dual Filter Voicing Unit $25/96 $26.95 "dead issue"; the original company HISSAWAY 13 Bipolar AC Adapter $9fi.9S $31.45 went out of business, and Ron 14 Treble Booster IB12.9 3 $11.65 Rivera is essentially supporting 15 Electronic Footswitch $19.95 $17.95 Radio Shack is now stocking *39.95 $35.95 it as a service to existing own­ 16 Tuning Standard the NE572 compander chip, which is 17 Super Tone Control $¥9.1)5 $26.95 ers. I find it completely under­ 18 8 in, 1 out Mixer (less XLR) $\sh8 $26.06 standable that he's not going to described as being "intended for 20 Practice Play Along • $ y 95 $22.45 noise reduction in high quality $M .95 $49.45 put any more time and effort into 21 Phase Shifter 24 Tube Sound Fuzz spi95 $20.65 it than he is currently. audio systems". I have enjoyed 25 Envelope Follower $2(395 $24.25 As far as not advertising in your columns in Keyboard and Gui­ 26 Splutter (less optional parts) $14:95 $13.45 tar Player for several years, and 27 N oise Gate A 32 ^ $29.65 Polyphony, don't be too hard on ADD $3.00 POSTAGE AND HANDLING WITH YOUR ORDER. RMS. Occasionally, people who are I feel that a refined version of These are kits of parts and circuit board only, otherwise intelligent and aware the 572 circuit given with Radio to allow maximum flexibility in their application have unexplained lapses of judg­ Shack's parts data would greatly no cases or enclosure are included. Instructions serve the many readers of your for the assembly of each item are part of the ment, and fail to advertise in book Electronics Projects For Musicians ($14.95 Polyphony. Luckily, Linda Kay columns and books. If you know of plus $1.00 postage) and are not duplicated with (our managing editor) is doing her any applicable circuits, I would the kit. best to help these people so that greatly appreciate your sugges­ CHARGE TO VISA OR MC TOLL- FREE they may once more regain their tions . 1*800-654-8657 9AMto5PMcsT mon fri status as respected members of the DIRECT INQUIRIES TO: electro-musical community. Robert MacArthur m iA Electronics, Inc. Re PAIA, their 4700 series Iowa City, IA 1020 W. W ils h ire , O klahom a City, OK 73116 - (405)843-9626 \

4 Polyphony ------A p ril 1983 Robert — The 572 is still a any sort of regular or irregular Adopt This relatively recent chip and not pulse train. I've been using Mean Little Kit that many circuits including it these to clock analog sequencers, have been published. However, it sample and holds, and electronic does seem good for noise reduction switches. The tempo up/down, sin­ (among other things) and if I ever gle play, repeat play, and tape get any spare time, I definitely load/save pads have all provided want to check it out for several useful variations to the basic circuits I have in mind. In the idea. For example, tape load/save meantime, do any readers out there allows you to store your timing have any good noise reduction data on a cassette machine for circuits based on the 572? You future uses so as to not eat up tracks on your big machine for know where to send them. Take home this 24-piece kit of electronic tools storage. Using the single/repeat designed for engineers, scientists, technicians, mode gives easy flourishes or students. Includes 7 screwdrivers, adjustable INVOKING THE MUSE... ostinato effects. Of course, the wrench, 2 pair pliers, wire stripper, knife, align­ tempo up/down pads control the ment tool, stainless rule, hex key set, scissors, 2 flexible files, burnisher, soldering iron, solder I have two Muse binary se­ relative speed of the timing pulse aid, coil of solder, and desoldering braid. High­ quencers in need of repair. These data. One thing I haven't been est quality padded zipper case measures ap­ able to try is using it with a proximately 6 x 9 x 1-3/4” inside. Satisfaction were made by Triadex, which is guaranteed. Send check, company purchase long since out of business. Can programmable, syncable device a la order or charge VISA or Mastercharge. We pay any readers provide schematics or TR-808, TR-606, etc. as I do not the shipping charges to your door. troubleshooting tips? I really own any of these devices. Ad­ JTK-6T00I Kit...... $95.00 think they're great little devices mittedly, this approach isn't as elegant or versatile as the "Mas­ and would very much like to get Free Catalog! them fixed. ter Synchronizer" presented in the Page after page of hard- Keyboard articles, but I've had a to-find precision tools. Also contains complete Art Noel lot of fun with it and it has line of tool kits and tool cases. Send for your free Box 913 allowed me to exert more detailed copy today! Havertown, PA 19083 control over synchronized sounds in my recent experiments and pieces. jeisiseisi t o o l s in c . 7815 South 46th St., Phoenix, AZ 85040 MURPHY'S LAW CONFIRMED! The click and sync pads on Phone:602-968-6241 TWX:910-950-0115 the 8700 .(running SEQUE 1) are I have just attempted to also very useful as detailed by build Jacque Boileau's Analog De­ John Simonton in "Friendly Stories lay Clock Modulation project about Computer s/Synthesizers". (March/April '82). Upon closer One idea I haven't looked into Makeyour inspection I found the pinout of would be to add some code to SEQUE the TL084 does not match the pin 1 which would allow you to program designations for inverting and a variable click track rate. key- J 5 | non-inverting inputs for IC2, 3, Then, the 8700 could provide tim­ and 4. All four op amps are con­ ing pulse control data directly at figured in the non-inverting mode its cassette output (just as the according to the figure 2 diagram current fixed rate click track on page 27. does). Or, if the "metronome" Please pass this along to rate could be made variable it your readers so they don't get too might serve as well for the pur­ frustrated building the thing. pose. It’s ironic that while the electronics of your syn­ thesizer is capable of sublety of tone and color T. Figueiredo David Vosh that are unprecedented in the history of music, you would be better off playing a typewriter for San Francisco, CA Upper Marlboro, MD all the control of dynamics and expression you have from the keyboard. Now you can change that with PAIA’s new Veloci-Touch Controller. SOLO/MUTE UPDATE This simple to build and install retro-fit for most SYNC OR SWIM, CONTINUED electronic keyboards adds three important con­ trol parameters: I really enjoyed Craig's ar­ I've recently made a number ■ Second Touch Pressure — pitch bends and ticles in the 1/83 and 2/83 issues of improvements to the Solo/Mute vibrato the natural way. ■ Velocity — as you play harder, output signal of Keyboard magazine on synchroni­ circuit presented in the Sept/Oct level increases. zation, and here's a tip on doing 1982 issue of Polyphony, listed in ■ Velocity Transient — apply to filter or voltage sync with PAIA equipment. I'm the order of importance: controlled distortion device for dynamic timbral 1. I increased the cutoff changes. using a PAIA 8700 system (micro­ And best of all is the incredibly low cost. Retro­ computer, encoded keyboard, cas­ voltage at the control points by fit versions are available from less than $45.00. sette interface, linear D/A, 2X changing the Zener diodes from 7.5 Stand-alone package with case and power supp­ to 12V. I was having problems ly (shown in the photo) less than $70.00. Quash, dual digitizer) and have Get the full details from our latest catalog of been able to use the SEQUE 1 pro­ with the unit passing transients electronic kits for stage and studio. It’s yours gram to create timing pulse during loud musical passages, and FREE by calling: tracks. By entering "notes" (com­ this took care of the problem. 1- 800-654-8657 bination of a "pitch" CV and a 2. I dropped the resistor gate) using the score or event ...... continued on page 7 A iA Electronics, Inc. modes, it is possible to create 1020 W. W ilshire , Oklahom a City, OK 73116 - (405)843-9626

Polyphony A p ril 1983 5 Robert Carlberg’s' ~i iniQi ic vm u happily presents its first installment of fine recordings. re-view FROM GERMANY: the Pilz. Ohr. & Cosmic Music Please note: The Sept/Oct '82 This 1982 reissue, after having reissues, with original cover art column listed Philip Perkins' been unavailable for several and labels. Neighborhood with a Sky incorrect­ years, is a crystal-clear digital­ ly as Neighborhood with a View. POPOL VUH - $9 ly remixed direct metal master In Den Garten Pharaos pressing. It ranks with Tangerine Hosianna Mantra Prince 1999 (Warner Bros. 23720- Dream's "Atem" as the apex of the Seligpreisung 1). Foregoing falsetto and many genre. Einsiager & Siebeniager of his other soul trappings, Aguirre Prince is making a strong bid for The The Uncertain Smile (Sire MANUEL GOTTSCHING - $9 a rock crossover. Keyboard syn­ 29878-0). A 3-song 12" EP with Inventions for Electric Guitar thesizers, toe-tapping grooves, all the parts (synthesizers, gui­ and unbridled hedonism are his tar, bass, drums, flute, sax, and WITTHUSER & WESTRUPP - $14 means. As a double record it's Live 68-73 vocals) by one guy, Matt Johnson. too long, but at least it's priced It's remarkably accomplished, with BROSELMASCHINE - $9 like a single LP. several nice touches. Live '68-73 EMTIDI - S9 DEVO Oh No! It's DEVO (Warner Roy Finch Fiction Music (POL 1 st Ip Bros. 23741-1). If fame is mea­ 0.11/2000). Pleasant electropop Saat sured by how many people steal featuring rhythm box, controlled your stuff, then DEVO must be one synthesis and Finch's restrained GURU GURU - $9 of the biggest. Because of that, Ufo singing. Lyrically and musically Hinten though, their trademarks are Finch doesn't seem to have any threatening to become anachron­ particular axes to grind, showing JAPANESE POLYDOR: isms, making it difficult to aban­ a refreshing lack of pretense. these long-out-of-print Ips don yourself to them. are available on superb Japanese Gen Ken Collaborations (cas­ press: they feature all original Steve Winwood Talkihg Back to the sette). Heavily-electronic ex­ artwork and lyric sheets and are plorations into uncharted dark on the original Polydor label. Night (Island 9777). Both Prince and Winwood use modern technology continents, using combinations of FAUST r $12.50 to record all the parts them­ rhythm box, white noise, basic 1 st Ip (black & white cover) selves, not for egocentric or synthesis, processed talking, and So Far (with pictures) economic reasons but because they tape manipulations. The mood is LATTE E MIELE- $12.50 can. This isn't his most inspired generally fearless, as on his Papillon writing, but there's always a time first tape (see May/August '82). (their best, fold-open for just good music. $6 from Ken Montgomery, 118 East with color insert) 4th Street #11, New York, NY ANTHONY MOORE Jean Piche Heliograms (Melbourne 10003. Pieces from the Cloudland Ballroom 4045). Digital synthesizer di­ (Rec. in Faust's studio with gitally recorded playing gorgeous David Ocker Two Pieces by David Faust members) drones, Reichian pointillism, and Ocker (cassette). One of the SLAPP HAPPY - $12.50 sweeping brushstrokes of tonal pieces is for Ocker's own over­ Sort Of color. It's very other-worldly, dubbed clarinet, the other is for (Original front and back cover, indicating there's a whole other solo viola played by Roland Kato. with Faust) culture in Canada besides Bob & Both seem essentially random and Doug. self-perpetuating. $9 postpaid from Fun Music, 2315 Jackson Electronic Art Ensemble Inquiet­ Street, San Francisco, CA 94155. ude (Gramavision 7003). By va­ Please write for a free catalog. rying the density and using some Scott Fraser Natural Histories TO ORDER: non-electronics such as voice, (cassette). Mostly long drones Please send money order, include organ, piano, guitar, and bass, meant to sound synthetic but ac­ $2.50 for 1st Ip and 50C each the E. A. E. is able to make this additional Ip. All orders sent via UPS tually made up of other sounds or 1st class mail. improvisational electronic cater­ processed. Some fascinating Phone orders are most welcome. wauling a fascinating experience. transformations. $8 postpaid from Lots of Zappa-esque tape speed Fun Music (see above). UNIQUE VINYL tricks. P.O. Box 23846 - Phoenix, AZ 85063 David Stout All Known Rivers 602-247-1778 Eberhard Schoener M e d i t a t i o n (cassette). Gentle, peaceful (Kuckuck 059). A ten-year-old soundscapes for synthesizer and classic of atmospheric synthesis. tape, perhaps best likened to

6 Polyphony------A p ril 1983 "Music for Films" Eno or Kitaro's the unique tonalities. 132 West "Ten Kai". Most of it is exceed­ 24th Street, New York, NY 10011. ingly subtle and accomplished. Direct from Stout at 114 NW 30th, The View In a Strange Land Corvallis, OR 97330. (Videoview 444; e.p.). John Craig Blaine, who wrote, produced, Robb Murray Classical Mosquito! sings, and plays guitar and syn­ (e.p.). 8 neo-baroque pieces of thesizer on these three tunes, is values on the positive side of organ-voiced synthesizer. Murray, a talented guy. Not only does he each control point from 100k to more at home on a typewriter key­ wear a lot of hats, but the quali­ 5.6k (!!). This runs both the board than the black and white ty of the writing is easily as Zener diodes and the 2N2222s in variety, has deftly programmed his good as any of the techno-pop you the switching part of the circuit compositions to play themselves hear on the radio. His bassist much closer to their recommended using an "Orchestra-80" program on and drummer are pretty hot too. operating limits. The result was a Radio Shack TRS-80. He's right 99 East Street, Easthampton, MA a much more stable cutoff voltage — "There's nothing eerie or eso­ 01027. at the control points, hence qui­ teric about these pieces of music" eter switching glitches. John Wiggins Tuned Space (cas­ — just delightful organ minia­ 3. I determined the optimum sette). More space than tunes, tures with a modern twist. $4 operating voltage for the entire Wiggins explores the underbelly of postpaid from Murray, 444 St. circuit to be 30V, and included an Serge and Moog synthesizers. He James Place, Chicago, IL 60414. on-board LM317 regulated power avoids the usual pitfalls of ab­ supply. This was necessitated by stract "art-music" by staying away 400 Blows Beat the Devil (Con­ the fact that I increased my phan­ from the obvious and emphasizing crete 002; single). The spirit of tom power to the industry standard his incredible variety — from of 48V, which pushed the circuit Throbbing Gristle lives on -- tape manipulations to gated mumbled talking, drone trumpet, over the edge as far as a few of rhythms to computer music to quiet pulsing bass, tapes, weird percus­ its design parameters were con­ drones. 15 Reservoir Avenue, sion. Nice job lads, but it's cerned . Northport, NY 11768. been done before. Concrete Pro­ I also have some comments ductions, 47 Oak Avenue, Shirley, about the last paragraph which was Bill Nelson The Love that Whirls Croyden CR0 8EP, Surrey, England. added to my original article. (Diary of a Thinking Heart) (PVC While FETs used as gate-controlled 101). The main disc is pop songs amplifiers are indeed prone to

Steve Meehleder The Collection dressed in electronic clothes. distortion, the situation here is (cassette). Recorded "after work Nelson's octave-jumping vocals a little different. The 0.01 uF and on weekends", this tape epito­ draw you in, and the solid produc­ cap between the source and gate of mizes the grass roots electronic tion holds you. A user-friendly the FET makes the thing almost music explosion. Intricate tex­ disc. The bonus disc of instru­ like a passive element throughout tures and deliberate mixing take mental incidental music to "Beauty most of the audio range. I've precedence over keyboard pyrotech­ and the Beast" probably loses checked this circuit out on a nics, although the pieces have something in translation — short 'scope and find it to be linear more than a passing classical synthesizer settings are razor-cut within the limits of my equipment, influence a la Synergy & Vangelis. together, giving a disjointed and, eyes, and ears up to about 20 dBm. 1610 J Avenue NE, Cedar Rapids, well, incidental overall impres­ In any event, I use it in a cue or IA. sion. monitor mixing circuit which doesn't require the utmost fideli­ Schaltkreis Wasserman Psychotron Peter Schafer Extension (cas­ ty. I don't really think you need

(Mercury 6367-042). Some sort of sette); Panta Rhei (cassette). to patch into the mixer system as central timing source is used to Co-founder with Rudiger Lorenz shown in figure 2, especially if synchronize synthesizers, elec­ (May/Aug '82, February '83) of you are not using the circuit in tronic percussion, and arpeggia- their SYNTAPE cassette label, this the main signal path, and the most tors. The result is tight-knit 20-year old West German shows what logical place for the circuit is tunes with frequent key changes can happen when a synthesizer as part of a cuing or monitoring and counter-melodies. Swiss-citi- falls into the hands of a skilled sys tem. zens Daniela and Peter Wasserman keyboardist. He's got a classic­ ally-trained musician's interest also include some cut-and-splice Lindsay Haisley tapework, a drone piece, and some in the way lines of notes inter­ Austin, TX singing (in German). There's more react, plus the synthesist's fas­ than enough variety and plenty of cination with the tonal and ex­ HELP! solid musical value. pressive possibilities of the syn­ thesizer. Carl-Ludwig-Schleich For a book on Thaddeus Cahill Port Said Eve of Departure (cas­ Strasse 5, 7518 Bretten, W. Ger­ and his Tel harmonium (1892 - sette). Like their previous sin­ many . 1911), the first electronic music gle (May/Aug '82) and cassette synthesizer, I would appreciate (February '83), this duo seems to Synarios Uncontrolled Voltage any information on letters, re­ delight in defying categorization. (cassette). A "live to tape" cordings, or other materials. Unusual percussion and their own collaboration between Lauri Pais­ ways of using synthesizers make ley and Don Slepian. A number of Reynold Weidenaar them sound unlike anyone else. electronic keyboards are employed 5 Jones St., Apt. 4 You won't be tempted to dance to to create a lot of variety for a New York, NY 10014 their music, but you'll marvel at ...... continued on page 11 ...... continued on page 31

PUfiyphony A p ril 1983 7 " ■'.. :: . ■ : ■ '.' ■ ^ ■ : '■ ■■ ■ ' : ^ ■■ v ■ ■ ■ . Voyetra Eight

Octave-Plateau's Voyetra Eight is a multi- same note, giving a big fat sound not unlike the old featured, eight voice polyphonic synthesizer. It niinimoog sound. comprises a modular approach, with a five octave On first glance, the front panel may appear keyboard and separate 19 inch rack mount mainframe confusing, but after a couple of sessions, creating (see photos); t

8 Polyphony A p ril 1983 source is selected using the number on the keypad Not all Wireless (only 0-7 will respond at this point). Each of these sources may be inverted if so desired. A destination is then selected with the appropriate Microphones button in the grey section (Q, filter center fre­ quency, VC01, or VCO 2). are Created Equal By advancing the Stepper forward to the prime state, you can then select the amount of modulation and a controller through which you may send the modulation. The controllers available are +X and -X (on the joystick), filter cutoff pedal, keyboard pressure, keyboard velocity, noise, and ADSR 1. The controllers are selected again by the grey section buttons, and the amount of modulation by touching the keypad. This will add or subtract a given amount and be displayed by the Step LEDs. In addition, you may also create patches using an Apple Computer which is connected either by the game paddle connector or a parallel port. In this mode, the Apple screen will reflect the Voyetra state and patches may be stored or called from the Apple's diskette and placed in the Voyetra memory (in any sequence). A future software package will allow an Apple/Voyetra system to compose and score music, as well as store sequences of notes. The Keyboard. The five octave keyboard fea­ tures a joystick controller and two stepper switches. These switches may step forward or back­ ward through the patches. The joystick provides-a pitch bend on the +Y and -Y parameters while the +X and -X are programmable for a number of functions. There is also a keyboard pressure and a pitch bend This One Is A adjustment. The keyboard connects to the main unit with a standard Cannon (3-pin) connector. Telex Two features of the Voyetra not normally found Recommendations by performers, as well as engineers, have in most systems are keyboard velocity and pressure. made Telex the fastest growing wireless mic system in At first, you might not realize the subtleties in­ the industry. volved with this system. Velocity is a voltage Performers tell us they prefer Telex wireless mics because of proportional to how quickly the key is depressed, the rich, full-bodied sound. And because the mics feel and look like conventional microphones. while pressure is a voltage proportional to how much To quote performers:...the Telex wireless mic sounds superior weight is applied to the keyboard. Once you ex­ to any I’ve used for vocals—wired or wireless... perience this, you quickly adapt your technique to ...the freedom it gave our group sold me on the concept, and make use of these features. For instance, by in­ the sound sold me on Telex... verting a DC source, using velocity as a controller, Audio and broadcast engineers stated that they prefer Telex and controlling the filter frequency, you can close because with just the addition of a second antenna, they have the filter by playing quickly and let it remain open the most reliable diversity* wireless mic receiver available, indoors or out. And because the compander circuitry provides by playing legato. You could just as easily set the dynamic range from a whisper to full fortissimo. pressure to trigger a vibrato, thus allowing you to To quote engineers:...the Telex wireless is the best we’ve emphasize different notes in different ways — with­ tested, and we've checked them all... out taking your hands off the keyboard. ...from a quarter mile, the signal was still crisp and clear... An optional expansion card, which plugs into an ...for the money Telex outperformed all others we tried... available slot in the mainframe, adds a number of When you're ready for wireless mics, Telex offers you a choice features to the instrument including a parallel port of three VHF frequency groups, hand held or belt-pack trans­ and 128K or EPROM; so, you can expect future soft­ mitters, dynamic or electret microphones and a host of accessories. Compare our specs against any others, and by all ware enhancements as they become available. Current means, compare the price. We’re quite certain you’ll also prefer software additions are: 100 patch storage capabili­ Telex. Made in USA. Please write for full details. ty; two additional LFOs (with selectable waveforms); *US Patent No. 4293955 Other patents applied for. velocity controlled attack; keyboard controlled Quality Products for the Audio Professional decay/release; more control over pulse width modula­ tion; and expanded arpeggiation features. Conclusion. The Voyetra combines the precision and "repeatability" of digital circuitry with the richness and economical advantages of analog cir­ cuitry. Since the operating system of the instru­ ment is in software, modifications and updates are made by changing EPROMs and not hardware. While not exactly inexpensive (the list is approximately $5,000), the Voyetra's design and craftsmanship will allow you to create sounds which are a notch above the competition.------• TELEX COMMUNICATIONS, INC. 9600 Aldrich Ave. So., Minneapolis, MN 55420 U.S.A. polyphony------Europe: Le Bonaparte—Office 711, Centre Affaires Paris-Nord, 93153 Le Blanc-Mesnil, France. 9 The Rockman provides four different sounds that can be se­ A Pnoduct Review lected with a four position slide switch. Two of these are"clean- sustain" type sounds that use designed to act as a system, the compression techniques to give the noise level is lower than when I guitar a ringing quality. It Bif: Kink Austin use my separate processors. This appears that the main difference also frees up a lot of my equip­ between these two sounds is the ment for other use (like process­ equalization, since one of the ing Thomas Henry's Snare+, which tones is bright, while the second I suppose that the premise of I'm also enjoying using). is more mellow in character. The this review will be hard to be­ Probably the most exciting remaining tone colors incorporate lieve for some of you, but I think thing about this .product is the the "tube-overdrive" simulator; that we are starting to see the tube-overdrive simulator. I have one of them is relatively mild and beginning of the end of big stacks always been a fan of tube ampli­ sounds a lot like my 1953 Fender of tube amplifiers. The Rockman, fiers for guitar, and none of the Deluxe, while the remaining timbre manufactured by Scholz R & D, solid-state circuits that I had can be compared to a Marshall represents a significant break­ heard really sounded like tube stack type sound. All four of the through with respect to equipment distortion to me. It seems that basic timbres use the chorusing for the professional guitarist. the critical portion of the sound and delay circuits, although there Running off of eight "AA" penlight is when it is decaying, since tube is a switch to cancel those ef­ cells or an AC adapter, the Rock- amps have a characteristic decay fects. The owner's manual indi­ man gives the musician more con­ that is pretty hard to get with cates that tuning should be done trol over that elusive tube-over- solid state devices. I was first with the chorusing turned off, so drive sound, combines this with a convinced that "the sound" could I can see why that switch is built-in effects chain, and de­ be implemented with solid state there. But, as soon as I cancel livers all these sounds in a pack­ devices when I heard Allan Holds- either one of those effects I age small enough to fit in a gui­ worth play through his new Hart- realize how important it is to tar case! As if that weren't ley-Thompson amplifier about a creating the total sound, and I enough, it also drives stereo year ago. Now it seems that Tom immediately switch it back in. headphones (provided with the Scholz, the Rockman's inventor, In talking to people about unit) for practicing without dis­ has figured out how to do it also. the Rockman, I have heard com­ turbing others. And when I say In my experience, the Rockman is plaints that there are not enough stereo, I mean STEREO — it's a the best tube-overdrive simulator controls on it to vary the ef­ very big sound. that I have ever heard. As the fects. However, I don't miss the Perhaps the deciding factor note fades away, it sounds just half dozen or so knobs that would in my decision to sell my Marshall like a tube amplifier to my ears. be necessary — four great sounds amp and buy the Rockman was the Combining this overdrive effect at the flip of a single switch is fact that the sound of the Rockman with the chorus/delay results in a much more desirable than a thou­ is excellent for recording. The pretty impressive sound. To get a sand mediocre sounds that take a amount of outboard sound process*- powerful sustaining tone — pre­ good deal of thought and effort to ing gear that the Rockman replaces viously only possible with a good achieve. In this sense, I think is pretty remarkable: compres­ deal of heavy, expensive, noisy that Scholz R & D has done a great sion, tube-simulation, equaliza­ equipment -- all I have to do is service to guitar players: Since tion, and chorus/delay. Since all patch the Rockman into my mixer. of this is in one package and I love it! ------

10 Polyphony A p ril 1983

i This Heat This Heat (Piano THIS- 1; 1978). Turns rock inside out through extensive effects and pro­ it is now a simple matter to get re -v ie w cessing. Bowled me over when I good tone quality, we can concen­ first heard it; it still does. trate on the more important (in my opinion) aspects of playing that continued from page 7...... Robert Wyat,t Rock Bottom (Virgin come from the hands. two-piece, though the improvised 13-112; 1974). Commemorating his The other controls on the nature of the pieces limits the stay in the hospital, this remains one of the most effective mood Rockman are a three position vol­ amount of rhythmic and harmonic pieces ever released. ume switch, and an input attenua­ experimentation. $7.95 from Don & tor which is a screwdriver adjust­ Judy Records, PO Box 836, Edison, Darryl Way Concerto for Electric ment on the back of the unit. The NJ 08818. input attenuator is nice, because Violin (Island 9550; 1978). An it allows you to tailor the sensi­ original classical piece for clear plexiglas violin and "orchestra" tivity of the compression and Demo Records/Tapes overdrive to the particular pick­ — amazingly synthesized by Fran­ ups in your guitar. The volume The Incredible Sounds of The Syn— cis Monkman. switch lets you match the output clavier II (N.E.D. 1/2). A 12" Claude Perraudin Mutation 24 signal with the equipment that you LP of demonstration without narra­ are using. Most mixers like to tion. The sixty 20-second doodles (RCA 37070; 1979). One of the see a standard line level, but most strongly musical e.m. efforts are by Denny Jaeger, veteran of "semi-pro" equipment like TEAC ever released, with synthesizers, VISA, Levi, and Chevrolet commer­ tape decks are set up for a signal drums, bass, and guitar all played cials. He sticks mostly to the by Perraudin in his home studio. level that is a nominal -10 dB. standard strings, organ, bells and The Rockman comes with a pair harpsichord sounds with minor Wendy Carlos Walter Carlos' of lightweight headphones that are variations — and the record real­ Clockwork Orange (Columbia 31480; similar to those sold with per­ ly is blue. sonal stereos, and there are two 1972) . Not the movie soundtrack, but what Carlos would have done output jacks so you can monitor on Just Fairlight #3 (cassette). had she had the time to do it the phones at the same time you Side A narrates how great this properly. Contains Carlos' best are going into a tape machine. $30K synthesizer is and provides original writing to date (iron There is also a stereo auxiliary short musical examples — but lit­ input for playing along with re­ included). tle technical detail. Side B cords or with another Rockman. presents the same examples without Hatfield and the North Hatfield I was impressed to find out narration. Considering the almost and the North (Virgin 2008; that there is a two year parts and unlimited potential of this ins­ 1973) . Why can't all rock be this labor warranty that comes with the trument, the conservatism of the congenial? Rockman. I'm glad to see a com­ examples is somewhat disappoint­ pany that stands behind a product. ing. I think that this is a very good Weather Report Tale Spinnin' (Columbia 33417; 1975). Every piece of equipment, and, consider­ The Emulator Demonstration Record Weather Report- album seems to get ing the number of effects it re­ Five selections on an 8.5" flexi- better with familiarity, but this places, is certainly reasonably disc, four of them presenting the priced. It is not, as some people usual rock, jazz, and classical one looms largest for its innova­ tive mixing and synthesizer work. would suggest, just a headphone sounds. The fifth is an ostenta­ amplifier for guitar; it is a tious narrated demo produced by Harmonia Harmonia (Brain 1044; sophisticated piece of signal pro­ Australian composer Andrew Thomas 1974) . Perhaps the most single- cessing gear that happens to be Wilson which at least hints at the minded of the German hardcore able to drive headphones. tremendous potential of an exter­ electronics of the early '70s. At Now, I'm not saying that nal-sound-recording synthesizer. everyone from Foreigner to Judas least until their second record. Priest will be running to their Brian Eno Another Green World local music store to trade in (Editor's Note: I recently asked their Marshall stacks for a Rock­ (Island 9351; 1975). The perfect Robert to compile a list of elec­ blend of pure sound experimenta­ man. Things don't change that tronically-oriented records which tion with tune-writing. Both have fast in the music industry. But, have gotten better with age for I am convinced that slowly we will been expolored further elsewhere those who are looking for good but not together. see a change occur, and that in a music they may have missed. Here few years solid-state amps will are his choices.) dominate the marketplace. It's Neu! Neu! (Brain 1004; 1974) and Neu! 2 (Brain 1028; 1973). The going to be hard to convince some Quiet Sun Mainstream (Island ideas, effects, and tapework are people, and I'm sure that a few HELP-19; originally released in still tops in their field. I people will never be convinced 1975). Instrumental rock from that solid-state can hack it no guess we haven't come that far in veteran Phil Manzanera which qui­ matter what the circumstances may ten years. etly bores in on your conscious­ be. But progress is being made, ness. Subtle use of electronics and the Rockman makes a strong Happy the Man Happy the Man and effects. case for solid-state guitar pro­ (Arista 4120; 1977). Extreme cessing to replicate that "oldie but goodie" tube amp sound. — # ...... continued on nage 31

Polyphony A p ril 1983 11 Switched-Capcrcitance Transversal Filters Theory & Practice

By: George Quiroga

T h e o ry

Two of the most recent advances in active fil­ ter technology are the "switched-capacitance" and "charge coupled device" filters. Both of these types of filters offer high accuracy, extended ver­ satility, a minimum number of supporting hardware, and relatively low cost. This article examines and compares the principle of operation behind, and the application of, these new filter components. Switched-capacitor principles. The simplest form of a switched capacitance filter can be derived from a standard passive low pass RC (resistance/ca- pacitance) filter. In the RC filter, the cutoff frequency is determined by the equation f=l/RC. If we fix the value of the capacitance and vary the resistance, the frequency f can be controlled. Substituting the resistance R with a pair of Field Effect Transistors on either side of the capacitor creates the "switched capacitor" (see figure 1). To show how this works, consider applying two complementary clock pulses on the gates of the FETs. When the gate of Q1 goes low, Q2 is high and the capacitor charges to value VI. Since Q2 presents a high impedance, there is no voltage at its output. When the clock changes state, Q1 shuts off and Q2 goes to a low impedance, thus discharging the capa­ citor to provide voltage V2. The circuit in figure 1 now reduces to the circuit in figure 2. The charge on the capacitor is Q=C(V2-V1). If we divide both sides by the time it takes to flip the switch back and forth, the equation becomes Q/t=C(V2-Vl)/t. Knowing that Q/t=I and l/t=f, we can further reduce it to I=C(V2-Vl)f. Finally, applying Ohm's Law (R=V/l) we obtain R=l/Cf where f is the clocking frequency applied to the two transistors. In es­ sence we have a variable resistor whose value is dependent on the clock frequency. We can now use this basic switched capacitor stage to replace the resistors in an active filter. Figure 3 shows this idea implemented in a basic low pass integrator. When used in an Integrated Cir­ cuit, the circuit of figure 3 is expanded to include four or more FETs (usually MOSFETs). The extra

12 P o ly p h o n y A p ril 1983 components help to stabilize the integrator by re­ ducing the amount of stray or parasitic capacitance inherent in the silicon sunstrate. Since MOSFETs

take up very little space on the silicon, successful Signal multistage filters can be produced. The advantage of this kind of filter is that the switched capaci­ XTXL,rT T h rrT x i tor stage requires less area on the silicon than the __T T . X , _T equivalent resistor it is replacing. This fact is especially true for large resistance values. There­ fore, the only limiting factor is the size of the o------capacitor that may be implemented on the silicon. The switched-capacitor filter can be configured to provide multi-pole highpass, lowpass, bandpass, figure 4 and notch filter responses. The frequency range, however, is presently limited from 0.5 Hz to 25 kHz. But since the dynamic range is greater than 80 dB and distortion is less than 0.1%, a switched-capaci­ tor filter can be used in most audio applications 1. One problem common to any kind of clocked or sampled signal device is the appearance of the clock frequency at the output. In a switched-capacitance filter, this clock residue is about 6 mV. Another problem deals with the sampling frequency itself. To prevent any kind of aliasing distortion, the sampling frequency must be much greater than twice the input frequency. CCD transversal filters. A charge coupled device stage is similar to the switched capacitor stage, except that each FET has its own associated capacitor. This capacitor/FET combination makes up a storage cell or charge packet. By clocking a signal into this storage cell and clocking it out, figure 5 one is essentially sampling the input. If each packet is connected in series and clocked in _an onance (Q) and center frequency. An example of this alternating but sequential fashion, the initial feature is found in Reticon's R5620 Universal Active charge sample is transferred down the line. Figure Filter5. Programmable filters can be used in compu­ 4 shows a typical CCD configuration. Such a device ter controlled networks for applications including is sometimes called a "bucket brigade" because it is spectrum analyzers, modems, and voice recognition analogous to the transfer of water buckets down a sys terns. line of people2. To make a filter from a CCD device, samples are 1. Arthur Makosinski,"What's Inside Digital Fil­ tapped off of the delay line and each one is multi­ ters", Radio-Electronics (May 1982): pp. 67-70. plied by a weighting factor. All of the weighted samples are then summed. The result is a signal 2. A. G. Milnes, Semiconductor Devices and Inte­ which has been multiplied by a function and then grated Electronics, (New York: Van Nostrand Reinhold integrated (figure 5). This process is the basis Company: 1980): pp. 610-617. for Fourier and other transforms. By controlling the weighting functions electrically, a charge 3. Alan V. Oppenheim, ed., Applications of Digital transfer correlator can be produced. This correla­ Signal Processing, (New Jersey: Prentice Hall: tor is sometimes called a programmable transversal 1978): pp. 129-140. filter 3. A transversal filter may achieve lowpass and 4. Reference 1, p. 69. bandpass responses at frequencies from 1 kHz to 1 MHz, with a dynamic range better than 40 dB^-. Dis­ 5. "R5620 Universal Active Filter", EG&G Reticon tortion is equal to the switched capacitor filter. Prelim inary Data Sheet, (Massachusetts: EG&G Cor­ The main limitation of a transversal filter is its poration: 1982). inferior high frequency response. The cause of this poor response is due to the sampling frequency, which must be fast enough to refresh the capacitors in order to minimize leakage losses. Therefore, transversal filters are not especially suited for most general audio applications. Conclusion. Both switched-capacitor and trans­ versal filters allow the circuit designer to imple­ P ra c tic e ment a filter with an integrated circuit which re­ quires very few external components. The only re­ EG&G Reticon of Sunnyvale, California manufac­ quirement is a stable external clock. For audio ture several CCD and switched-capacitor filters. applications, the switched-capacitor has excellent One of these, the R5620 Universal Active Filter, is specifications, and is lower in cost, when compared especially suited for audio circuit design because to a transversal type. Some types of switched- of its low cost, accuracy, versatility, programma­ capacitor filters offer a digitally selectable res- bility, and simplicity in design implementation.

Folyphony------April 1983 13 Description. According to the data sheet, "the ta b le 1 Reticon R5620 is a double-poly NMOS switched capaci­ tor universal active filter. It will perforin all FILTER TYPE LPIN HP IN BPIN five filter types and a programmable oscillator without external components. Only an external clock LOWPASS V IN GND GND is required." The R5620 has three signal inputs (HP, LP, and BP) which can be wired in different HIGHPASS GND V IN GND combinations to provide several filter types, in­ cluding notch and phase equalization filters. As an BANDPASS GND GND V IN example, a notch filter can be created by applying NOTCH V IN V IN GND an input signal to both the LP and HP inputs. Fig­ ure 1 shows the pinouts for the R5620 and its basic ALL PASS V IN V IN V IN configuration while Table 1 shows the pin connec­ tions for implementing the five filter functions and OSCILLATOR * GND GND V OUT the oscillator. To control the center frequency and the Q, there are ten digital inputs (five for "Q" and five * Q MUST BE SET TO 11101 for "FC") which are compatible with TTL or micropro­ cessor levels. The five pins which are used to vary the center frequency will accept any five bit digi­ ta b le 2 tal word and translate it to a ratio F clock /FC from 50 to 200. Similarly, the Q can be made to

Q Q4 Q3 Q2 Q1 QO vary from 0.57 to 150 in 32 steps. The 32 steps for frequency are logarithmically spaced which makes it .57 0 0 0 0 0 suitable for audio applications. To calculate the 5 1.05 0 0 1 1 0 bit words needed to generate a particular response, 3.0 0 1 1 0 1 Reticon supplies a look-up table in their data 10.0 1 0 1 0 0 sheet. Tying all frequency control lines to ground 40.0 1 1 1 0 1 results in F clock/FC=200, while tying them high 150.0 1 1 1 1 1 results in F clock /FC=50. Tying the Q control lines low gives a Q of 0.57 and tying them high gives a Q of 150. Tablej 2 shows a partial listing FCLOCK/FC F4 F3 F2 FI FO of values and their corresponding control words. 200 0 0 0 0 0 Figure 2a shows a multipurpose filter for pro­ 146.2 0 0 1 1 1 cessing a guitar or synthesizer signal. When using 102.3 0 1 1 1 1 a guitar, the guitar's output must be brought up to 74.8 1 0 1 1 1 a level acceptable to the filter. The high gain 50.0 1 1 1 1 1 •preamp of figure 2b works very well for this pur­ pose. (I use this preamp as a module in my synthe­ sizer so that I can process any guitar signal through my synthesizer's mixer as well.)

14 When constructing the multipurpose filter, I used DIP switches to set the Q and F control lines, but one may use switches mounted on a front panel for easier accessibility. Pull up resistors are a must on the control lines so these lines will be in either of two states and not floating; DIP resistor packs are useful for this function. The switches FCLOCK FO RANGE for the LP, BP, and HP inputs must have one side ties to ground when that particular input is not 10KHZ 50HZ-200HZ used. The op amp on the output is just a buffer to 20KHZ 100HZ-400HZ isolate the filter's output. 30KHZ 150HZ-600HZ A simple clock oscillator made from a CMOS 40KHZ 200HZ—800HZ CD4011 quad NAND gate drives the filter's clock 50KHZ 250HZ-1000HZ input. The CMOS gate also allows a pair of nine 60KHZ 300HZ-1200HZ Volt batteries to power the entire circuit, making 70KHZ 350HZ—1400HZ it very portable. For more advanced projects, you 80KHZ 400HZ—1600HZ can use voltage controlled oscillators to provide the clock frequency. The frequency of the oscilla­ tor in figure 2a is determined by the 10k potentio­ meter and the 0.0033 uF capacitor. Table 3 gives possible filter ranges for particular clock frequen­ cies. One should experiment with the potentiometer ta b le 3 and capacitor values of the clock in order to come up with the right clock frequency for the desired range. The frequency of the clock is determined by excels. I am presently working on a programmable the formula Fc=l/RC. filter which uses a microprocessor to provide not Using R and C values of 10k and 0.0033 uF gives only frequency and Q selection, but also phase a clock frequency of approximately 30 kHz which shifting effects. I hope this to be the basis of a provides a filter range of 150 to 600 Hz. Care must future article. be taken to keep the clock frequency out of the Acknowledgement. I would especially like to audio range or else it will be heard at the output. thank Reticon Corporation for their tremendous help; Also, an input signal at greater than half the clock without it, this article would never have been pos­ frequency may cause the R5620 to oscillate. The sible. problem of having the clock frequency appear at the output can be minimized by using a lowpass filter with the corner frequency set slightly higher than the filter's highest passable frequency. Using the Multipurpose Filter. Using the Mul­ tipurpose Filter is easy, but requires an initial calibration in order for it to be accurate. By using an oscilloscope or frequency counter, adjust the oscillator to provide the desired frequency range. A switch with 1% resistors may be used instead of the potentiometer to provide exact clock frequencies for several ranges. Once calibrated, the filter is ready for use. Select which type of filter you want by setting the appropriate input switches. Now select the correct corner frequency and Q by setting the appropriate controls switches, and you're ready to go. Availability of the R5620, as of the time of this writing, is limited. A list of distributors may be obtained by writing to EG&G Reticon, 345 Potrero Ave., Sunnyvale, CA 94086. Although the retail price of the R5620 is a low $7.50, Reticon requires a minimum $100 purchase when ordering di­ rect. Maybe there are a few dealers out there who would like to stock the R5620 and make it available to Polyphony readers. Although I have limited this article to a rela­ tively simple application, this is by no means the end. The purpose of this article is only to intro­ duce you, the reader, to a low cost, state-of-the- art filter. The R5620 is a very versatile device and I'm sure many of you will be able to expand on the usefulness of this chip. Other applications include: synthesizer effects modules, equalizer and spectrum analysis stages, and speech synthesis sys­ tems. Finally, one must not overlook the idea of tying the R5620 to a microcomputer bus. This con­ cept of digital control is where the R5620 really

15 T IB frftT T ft The Rane Corporation wires its 3 and 5-pin connectors per IEC 268 as follows, and suggests that you do likewise in your projects:

3-Pin Connectors

Pin 1 Ground (shield, screen, etc.) Pin 2 Positive (signal, hot, The Audio Connection. etc.) Pin 3 Negative (return, common, etc.) 5-Pin Connectors toy* D e n n is B o lin Pin 1 Ground Pin 2 Left Positive VP. Engineering, The Bane Corp. Pin 3 Left Negative Pin 4 Right Positive Pin 5 Right Negative registered trademark of ITT-Cannon Quality engineering necessi­ and cannot be legally used to tates standards, so this issue's describe any other manufacturer's 1/4" phone jacks. On Rane "Details" describes connector version of this connector. And equipment outfitted with input/- standards which parallel interna­ since very few people use ITT- output phone jacks, the wiring tional standards where applicable, Cannon XLR connectors, violation convention for standard ring-tip- and accepted practices elsewhere. of their trademarked name is com­ sleeve (RTS) connectors is: After reading this, you need never monplace. Until something better be in the dark again regarding comes along, we will refer to this polarities or jack wiring. In type of jack as a "3-pin connec­ Stereo 1/4" Phone Jacks general, we are a left-to-right, tor" . front-to-back, top-to-bottom so­ Tip Positive ciety — which has absolutely 3-pin connectors. Much to Ring Negative nothing to do with this article; many people's surprise there i_£ a Sleeve Ground it's just interesting. a standard for wiring 3-pin con­ nectors -- not two, as commonly Connector conventions. The believed. The conflicting so- Mono 1/4" Jacks single biggest source of wiring called "European" and "American" confusion in the pro audio indus­ standards are myths. There is one Tip Positive try is 3-pin connectors. Even standard. It is IEC 268, (short Sleeve Ground their name is a source of confu­ for International Electrotechnical sion. Most commonly called "XLR" Commission Standard No. 268, part jacks, they are also known as 12), and is titled "Circular Con­ For 1/4" RTS output jacks "Cannon plugs", "3-pin connec­ nectors for Broadcast and Similar designed exclusively for headphone tors", "XLR-type" jacks, and "cir­ Use". Created in 1975, signers to use, the standard is: cular connectors". The name con­ this international standard in­ fusion makes sense, since this cluded Australia, Belgium, Canada, Headphone Jacks type of jack has never been given Denmark, Egypt, Hungary, Israel, a generic title. Other connectors Japan, the Netherlands, Norway, Tip Left Positive used in audio are commonly re­ Romania, South Africa, Sweden, Ring i Right Positive ferred to as "phono" (originally Switzerland, Turkey, the UK, and Sleeve Comnon Ground called RCA jacks), or "phone" USA. In addition, the same con­ (1/4" jacks, after headphones and vention was adopted separately in telephones — their original the UK as BS 5428 (British Stan­ usage), or "DIN" plugs (Deutsch dards Institution No. BS 5428, If you wire your connectors Industry Norm), a German standards part 5, Section 3, 1980/81). according to standards, and use a organization and European stan­ There should be no conflict in standard input/output structure dard. Nothing comparable has connectors. There obviously is, (see previous "Details" columns on caught on for 3-pin connectors, so and that is a sorry reflection of the Gozinda/Gozouta universal I/O they have become known by the how badly informed are many manu­ stage), you'll be able to plug original manufacturer's model num­ facturers of pro audio equipment various devices together without ber. The original manufacturer (another reason why they should having to worry about...details. was ITT-Cannon and the model num­ read Polyphony to find out about ber was "XLR". Today, "XLR" is a stuff like this -- ed.).

16 “April 1983 B u ild a ia s s Pedal System

By: Stefan Hawk

H e re's a cost-effective set monophonic tone generator chip, trigger output to interface with a of bass pedals. This pedalboard waveshaping circuitry, selectable synthesizer (the synth needs an setup will operate as a self-con­ footage, variable decay rate, per­ external audio input for this tained system and/or interface cussive or sustain mode select, application). with a synthesizer. It contains a plus "raw" squarewave, gate, and How it works. The heart of the system is the M-147B-1, a 13 bit latch pedal sustain IC made by SGS-ATES (an Italian-based manu­ facturer). It supplies 50% duty cycle squarewaves over five oc­ taves simultaneously along with gate/trigger outputs. The outputs remain on until a pedal is re­ leased, and it has a left-hand priority when more than one pedal is depressed. The circuit requires +15 Volts DC; you can supply power figure 1 from your synthesizer or if you want to operate the pedals as a self-contained unit, use the power supply shown in figure 1. Current drain is small, so this supply is more than adequate even without a l------' I TIIKiP ' S heatsink on the regulator. Besides pedal switch con­ tacts, a high frequency clock is needed to drive and tune the range of the M-147B-1. Figure 2 shows a CLOCK OUT CD4001 CMOS quad NOR gate acting — o to pin 17 IC2 as a high frequency clock with a pot to tune it to 500.06 kHz. The l IC1 squarewave output isn't perfect, but is fine for this purpose. If you want to tune the pedals to different pitch sources, Pi should figure 2 be a panel mount pot instead of a trimmer. ------

IVriyphoi^ A p ril 1983 17 Now on to figure 3. Pin 1 is power. Pin 2 delivers a trigger 14 F# pedal switch contact pulse at about +14V going to 15 G pedal switch contact ground when a pedal is depressed. 16 G# pedal switch contact Q1 inverts this for a positive 17 A pedal switch contact going pulse at the trigger output 18 A# pedal switch contact (Q2 performs a similar function 19 B pedal switch contact for the gate output). Pins 3-15 20 C (high) pedal switch contact are the pitch select inputs for the pedal switches. Each input 21 Ground here has a pedal switch contact 22 System +15V which connects to ground, along with a 0.01 uF capacitor to de­ a Trigger out bounce it. Pin 17 connects to the b Gate out high frequency clock from figure c 16' on-off 1. Pins 20-24 generate the d 8' on-off squarewave outputs, ranging from e 16' to 1'. f Decay pot Figure 4 is the sound shaping g 16' direct out circuit. The 16' and 8' outputs h 8' direct out from IC2 hook into filters which i 4' direct out are switched on and off by quad j 2' direct out a analog switch IC3. The signals k 1' direct out are mixed at pins 2 and 3 before 1 Main output the final output, P3. The LEDs are optional, as is IC3 and the Using the bass pedal system. synthesizer interface (Q1, Q2, and You need an amp and speaker capa­ direct outputs G-K). ble of reproducing some low bass, Construction. Let's try to since 16' low C is 32 Hz. The 16' R37-41 68k tie this all together. You'll and 8' switches select either or R38, 43 12k need some pedals, but what about both. The percussion/sustain R39 100k that set the keyboard player you switch alternates between an auto­ R44, 45 220k know pulled off his Hammond organ? matic decay, or decay only after All you need is SPST contacts, the pedal is released. PI 5k (see text) with one contact going to the Interfacing with a synthe­ P2 75k (decay) appropriate pedal output (pins 3- sizer is straightforward: gate P3 50k (volume) 15) and the other contact going to and trigger outs connect to an a ground buss. Connecting these envelope generator, ‘while you mix two contacts initiates the note. whatever squarewave footage you Capacitors I suggest building the cir­ want to process into the external cuit on a Radio'Shack breadboard audio input. Cl 47 pF #276-152 and a mating 22-44 pin Finally, take some time and C2 1000 uF edge connector. I use these for care in laying out this circuit; C3 4.7 uF most of my projects, as they're it can be fairly tricky. Good C4, 19-25 0.1 uF easy to construct on and trouble­ luck and I hope you enjoy your C5-17 0.01 uF shoot with. Be sure to use sock­ bass pedals. C18 10 uF ets for all the ICs. They're all MOS devices and you certainly can't afford to blow up too many Parts list Semiconductors of the M-147B-1 chips. Here's the suggested pinouts PARTS AVAILABILITY NOTE: The M- Dl-4 (1N4002 from the circuit board to the edge 147B-1 is available to Polyphony D5, 6 1N914 or equiv. connector: readers for $10.95 plus $1.50 for D7, 8 LED shipping. California residents IC1 4001 quad gate Pin # add tax. Send check or money IC2 M-147B-1 1 order to: Hawk Music Systems, IC3 4066 quad switch 2011 W. 11th St., Upland, CA 2 External +15V suppply IC4 7815 +15V reg. 91786. Ql-3 2N3406, 2N5138 PNP 3 Q4, 5 2N5138 PNP 4 Fine tune pot Q6, 7 2N5133 NPN Resistors and Potentiometers 5 6 Perc. sustain switch RI, 3, 29, Miscellaneous Parts 7 31 10k R2, 18-23, 45 22k SI SPDT footswitch 8 C (low) pedal switch contact R4, 24-28, 30, S2, 3 SPST footswitch 9 C# pedal switch contact 42, 46-48 lk Sx Set of bass pedals 10 D pedal switch contact R5, 17, 33, 34 270k FI 1/4 A fuse 11 D# pedal switch contact R32 8.2k T1 R. Shack #273-1385 12 E pedal switch contact R35 3.9k 12.6 VAC @ 300 mA 13 F pedal switch contact R36, 40 6.8k ------•

18 Polyphony A p ril 1983 P o ^ p h o i^ A p ril 1983 19 POLYMART ------BOOKS SCIENCE OF SOUND The physical and psycho-acoustical background to music is an important part of musical syn­ thesis. Helmholtz’s SENSATION OFTONE is, a century after its publication, still the standard text for the 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 Helmotz work, with a bit less detail and more con­ centration on psycho-acoustics. #PSYCH PHYCHOLOGY OF MUSIC $6.00 #SENS ON THE SENSATIONS OF TONE $8.95 #MSS MUSIC, SOUND AND SENSATION $4.50 #MPE MUSIC PHYSICS AND ENGINEERING $6.50

REFERENCE Often used reference materials to answer the many questions encountered in everyday synthesis. THE SOURCE Book of Patching and Programming from Polyphony has over 125 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 dawings and schematics to answer any question about ratio. Hardbound. ELECTRONIC MUSIC SYNTHESIZERS by Delton Horn devotes the first half to descriptions and functions of commercial electronic music synthesizers (Moog, Arp, PAIA, Oberheim, EML, and RMI); the second section provides schematics and projects for the ex­ perimenter. #SOURCE THE SOURCE $4.00 #CYCLO AUDIO CYCLOPEDIA (hardbound) $44.95 ELECTRONIC MUSIC SYNTHESIZERS $6.95

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. MULTITRACK PRIMER by TEAC is a step- by-step guide to building, outfitting and operating your home studio. The Byte Book of COM­ PUTER MUSIC describes computer control of electro-mechanical instruments, Fourier analysis, circuits and loads of software. HOME RECORDING FOR MUSICIANS is Craig Anderton’s original guide to outfitting and operating a budget studio for maximum results, includes mixer and other audio processing circuits and a sound sheet demo recordinq. #TEAC TEAC MULTITRACK PRIMER $4.95 #BYTE BYTE BOOK OF COMPUTER MUSIC $10.00 #HRFM HOME RECORDING FOR MUSICIANS $11.95

' HOWTO” GUIDES HOW TO BUILD A SMALL BUDGET RECORDING STUDIO FROM SCRATCH by F. Alton Everest covers twelve tested designs. HOW TO DESIGN TEST AND BUILD COMPLETE SPEAKER SYSTEMS BY David Weems is a do-it-yourself guide for the ultimate in sound quality. HOW TO MAKE AND SELL YOUR OWN RECORD — With the major lables having severe economic pro­ blems, many insiders feel that the future of the music industry may be in independent record pro­ duction. Learn the ropes with Diane Sward Rapaport’s indispensable handbook of how to get started. MAKING MONEY MAKING MUSIC by James Dearing — Everyong dreams of being at the top, but there’s an enormous amount of “ middle money” out there for the taking. This is not a book about how to become a Millionaire Rock Star, but the strategies revealed will give you the knowledge you need to keep afloat if you decide to pursue a recording contract. A fresh and prac­ tical approach to staying alive in the music business. From the publishers of Writer’s Digest. #BRS BUDGET RECORDING STUIDO $9.95 #MASR MAKE & SELL YOUR OWN RECORD $11.95 #CSS COMPLETE SPEAKER SYSTEMS $7.95 #MMM MAKING MONEY MAKING MUSIC $12.95 ORDER FROM: POLYMART, POBOX 2 0 3 0 5 , OKLAHOM USE THE ORDER FORM ON THE NEXT PAGE 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-AMP and Don Lancaster’s ACTIVE FILTER Cookbooks are self-explanatory — required reading for synthesists! AUDIO OP AMP APPLICATIONS is an edited version of the Op Amp Cookbook by Walter Jung, containing only audio applications. Lan­ caster’s CMOS book is much more than a digital reference — phase lock loops, top octave generators, touch switches, and other things you need. ELECTRONIC PROJECTS FOR MUSI­ CIANS by Craig Anderton is almost in a class by itself. It discusses electronic construction technique for the novice and provides 27 projects with printed circuit board patterns and a demo recording of the effects. Even if you’re an old hand at musical electronics, you’ll appreciate that all of these processors, from Tube sound Fuzz to Phase shifter are compatible and work together without creating noise, signal loss, bandwidth compression or any of the problems common to in­ terconnecting effects from different manufacturers. There’s even a complete chapter on how to modify and combine effects to produce your own custom pedalboard. ELECTRONIC MUSIC CIR­ CUITS by Barry Klein covers synthesizer system design, power supplies, control voltage generators, VCOs, Filters, analog multipliers and more. Lots of schematics and data sheets on the most popular music oriented ICs. An excellent technical reference. #OACB OP-AMP COOKBOOK $15 95 #EPFM ELECTRONIC PROJECTS FOR MUSICIANS $14.95 #AFCB ACTIVE FILTER COOKBOOK $14.95 #EMCR ELECTRONIC MUSIC CIRCUITS $16.95 #AUOA AUDIO OP-AMP APPLICATIONS $8 95 #CMCB CMOS COOKBOOK $12.95

EXCITING NEW BOOKS! MUSICAL APPLICATIONS OF MICRO-PROCESSORS by Hal Chamberlain — If you only have space in your library for one book on music synthesis, this is the book. The easily read text is entertaining and enlightening and teaches both basics and advanced theory without plowing through pages of equations. Liberal examples illustrate theory and practice of both digital and analog signal generation and processing. #MAM MUSICAL APPLICATIONS OF MICRO PROCESSORS $19 95

THE COMPLETE GUIDE TO SYNTHESIZERS by Devarahi — An extraordinarily thorough treat­ ment of the subject of analog synthesizers. Covers everything clearly, and the suggested ex­ periments are excellent. Well organized and leaves nothing out #CGS THE COMPLETE GUIDE TO SYNTHESIZERS $15.95

PRACTICAL GUIDE FOR CONCERT SOUND by Bob Heil — Finally, a manual that explains in very simple language those many “ magic terms’’ you’ve heard for years and never really understood. It’s the first book written especially for musicians, roadies, and sound technicians who want to KNOW and UNDERSTAND what their sound system is all about. #PGC PRACTICAL GUIDE FOR CONCERT SOUND $10.00

&MORE FROM POLYPHONY 4/8TRACK STUDIO LOG BOOK designed by Craig Anderton provides a place to keep all the impor­ tant 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 indes counter. Craig Anderton's CONTEMPORARY KEYBOARD ARTICLES is a collected 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 con­ struction projects. Sold in complete set, individual issues not available. Limited number available. CRAIG ANDERTON MUSIC TAPE — Delightful listening plus a booklet explaining how the effects were achieved. #SLB STUDIO LOG BOOK $4.95 #AA CRAIG ANDERTON’S CONTEMPORARY KEYBOARD ARTICLES $5.95 #DEVICE COMPLETE SET (12) DEVICE BACK ISSUES $18.00 #CAMT CRAIG ANDERTON MUSIC TAPE $5.95 l CITY, OK 73156 (405) 842-5480 3ACK ISSUES $ 2.50 each ppd #0604: January/February 81: Special Construction Edition; Build: Audio Circuit Breaker, Pulse Width Multiplier. Magnetic □ Harp, 50 Watt/Channel Stereo Power Amp, Quad Sequential Switch, Find out what you’ve missed! DOD Mods, patches. ■ #0204: 4/76: music notation - timing, external inputs for #0605: March/April 81: Portable Music Issue, reviews of JGnome, Programmable Drums, Equally Tempered D/A, low cost AR Remco s FX, E-H Mini-synthesizer, Casio's VL-Tone, plus mods for project, digitally encoding keyboards, patches, Volume 1 & 2 □ the M-10. GR-500, mini-amp, and the Korg X-911. Introducing; index. Practical Circuitry and On Location, new columns. #0301: 7/77: frequency divider project, random tone generator project, normalizing synthesizer controls, eliminating #0606: May/June 81: Synthesizer: Hardware Mods and □patch cords, computer control of analog modules, Chord Egg Software. Modular Synthesizer Effects, Environmental music. modification, adding pitch bending, patches. □ Keyboard assignment for the 8700, new columns; Details, Practical #0302: 11/77: The Sensuous Envelope Follower, digital Circuitry, and On Location. Volume 6 index. ■•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, #0701: July/August: Guitar Electronics: Modify; Fender .— patches. □ Amp, MXR Phase 100, GR-500. Input/Output Structures, §5 Analog Programmer, Sample and ^Hold technique, Modular Synthesizer 1 1 . #0303: 2/78: computer controled Gnome, using joysticks, Effects, new column: Applied Synthesis, Marketing Your Records. build a bionic trumpet, ultra-VCO modifications, voltage control __the Mu-Tron Bi-Phase, oral joystick, patches. #0702: Sept./Oct.'81: Harald Bode Interview, Live Plus Tape New Technique, Xenharmonics, Kraftwerk Live - Review, L, J #0304: April/May 78: Minimoog modifications, non-keyboard □ Psycho-Acoustic Experiments, Practical Circuitry - Super module use, phasing and flanging (theory and circuits), memory Controller, Applied synthesis - Brass, Construction Tips For expansion for programmable drunfs, digitally addressed transposer Beginners. project, polyphonic software (with software transient generators), patches, Volume 3 index. #0703: Nov./Dec.'81: Dave Rossum interview, Applied #0402: Sept/Oct 78: electronic music notation, notes on Synthesis: Strings,Details: Series-parallel/Sum-Difference. The □the recording of "Cords" by Larry Fast, sequencer sqftware - part □ Sound Gizmo and Pro-One Reviews, Practical Circuitry: VCO Deluxe. one, rhythmic control of analog sequencers, touch switch projects, #0704 Jan./Feb.'82: Bob Moog interview, Chip Power - modular vocoder techniques, PET as a music controller, patches. ^ STK-050/070, Simple Square Wave Shaper, Tape Timer Ruler, #0404: January/March 79: add-ons for vocal F and V Practical Circuitry: VCAs made simple. Details: Gozinda & Gozouta Q,converter, shorthand patch notation, more on note to frequency Revisited, Korg Trident & Casiotone 202 Reviews. conversion, graphic monitor project, George Russell, super VCA circuit, echo software, Vol. 4 index. #0705 Mar./Apr.'82: Electronic Music Math, Analog Delay Clock / Modulation; Frequency Domain Modifiers; Screen-Wave for #0502: July/August 79: hex VCA/mixer project, electronic □ the TRS-80; Touch Switches Revisited; Practical Circuitry: ADSR □Imusic schools and studios, modify the Oberheim Expander Module, profile of Ernest Garthwaite, budget microphones, digitizer the Easy Way; Getting the most out of a Cheapo (Guitar). projects and software, bar graph ICs. #0706 .May/August '82: Anatomy of a Private record, Don Slepian Interview, Understanding Digital Synthesizers: A Digital #0505: January/February 80: Joseph Byrd, Mort Garson, □ Filter, Syn-Bow Review, Optical Audio, Profiles of SSM 2033 & □Larry Fast on 'Games', composing fpr 'live plus tape', using the CA3280, recording vocals, ADSR circuits. 2044, The PAL Filter, Bill Rhodes Applied synthesis: Bells, Pipe Organ, Harpsichord, Electronic piano; The Realistic MG-1 Reviewed. #0506: March/April 80: Computers in Music: real time audio □processing hardware, Powell sequencer system. Max Mathews, advanced STG software, PortaStudio, phase modulation, Volume 5 #0801 Sept/Oct.'82: Ambience in Electronic Music,Tone index. Bypass for Fender Amps, 8 Track Reviews, Parametric EQ Tips, □ #0601: May/June 80: Gary Numan, Microcomputers in Real Solo/Cut Circuit for TASCAM Model 3, The SSM 2011, Tube Preamp, Time Audio, Build a Digital Audio Delay Line, writing Snare + Drum Voice Circuit, Triple Pick-up Switcher, Simulated □ Documentation, Richard Hayman Composer/Performer Home Recording: Stereo, When Quality Reocrd Mfg. Counts, Independent Record Mfg. Applying Harmonizing and Pitch Transposing Techniques by: Craig Convention report. Anderton. #0602: July/August 80: Peter Gabriel, digital VCO #0802 February '83: AMS-100 Gate Output, Bus Distribution project, dream modules, optimum level settings, dynamic phrasing, Modules for Modular Synthesizers, Dynamic Touch Controller, □ patches. □ Expanding Envelopes, MXR Limiter Review, New Age Music, An #0603: Sept/Oct combined with Nov/Dec 80: alternate Overview, Synsonics Drum Review, Interface, Practical Circuitry: A controllers, add voices to Casio M-10, voltage controlled Patch Over Scheme for Small Synthesizers, Lab Notes: Shepard □ quadrature oscillator project, cordless patch bay, recording Functions. rules, patches. CASIO M -10 OWNERS...... RACK PANEL SPECIAL! Did you realize that your pride and joy has unseen powers? That there are voices And effects that you can add for the Easily machined 1/8 inch unfinished aluminum rack panels as cost of a switch and a piece of wire? This latest booklet low as $3.95 each in quantities of 3 or more, (you may mix from POLYPHONY gives you the info that you need to transform sizes for discount prices) your mini-axe and gives details on adding a "stunt box", computer interfacing and much,,much more. Quantity T 3 or more No. CMOD 16 pages ...... $3.50 single size - 1-3/4" .$5.25 $3.95 each double size - 3-1/2" .$9.25 $7.95 each SSM 2011 CHIPS triple size - 5-1/4" $12.95 $11.95 each As a special service to readers interested in evaluating this exciting new chip, for a limited time POLYMART offers the SSM 2011 Microphone Preamp/Level Detector IC. No. 2011 .... $5.75 each plus postage ($1.00) ORDER FORM------Quantity Item price ea. amount J We cannot invoice; payment must be enclosed with your order. J there is a flat $.50 handling fee per order plus postage costs. I MasterCharge and Visa are -welcome, ($10.00 minimum charge ). Foreign orders must be paid by certified check or • money order in U.S. $ drawn on a U S. bank (or by charge c a rd ). Phone orders welcomed for charge card orders. SHIP TO: Name: ______Address: ______

City ______S ta te ______Z ip ______0 - —n SUBSCRIPTION u.s. $ia/YR . f o r e ig n s -i c / y r . subtotal ■ U.S.:add 10°/o of Sublotal handling .50 | Card #__ o r $5.°°m axim um I MasterCharge Bank # ______Expiration Date Foreign: 20°/oof SubTotal shipping or SB10P°rnaximum ■ Signature ______total enclosed MAIL t o : POLYMART, PO BOX 20305, OKLAHOMA CITY, OK 73156 ( g M B I M K n r i w e m n r § Tell Them You Saw It In Polyphony ’

CMOS 6502. Rockwell Interna­ tional (4311 Jamboree Road, New­ port Beach, CA 92660) has an­ nounced the R65C02, a CMOS version of the 6502 microprocessor that accepts clock speeds up to 4 MHz, includes 12 new instructions, and draws about 5% as much current as its NMOS equivalent.

Calling all musicians. M ak­ ing Money Making Music, by James Dearing, is a sympathetic, fact- filled, 320 page book which looks ^ New spring reverb, compres- cassette players, practice amps, at how musicians can make a living sor/limiter, lower price. Fostex monitors, etc. It includes bass, by concentrating on good-paying, (15431 Blackburn Ave., Norwalk, CA treble, and volume controls. local jobs (orthodox and unortho­ 90650) has announced the 3180 2 dox) rather than the elusive pot channel reverb (list $400). It of gold of national stardom. His features built-in pre-delay and words are to the point, and show limiter, LED overload indicator, the compassion and humor of some­ and paralleled front/back panel body who's "been there". Delivers input/output jacks. what the title promises. Pub­ The 3070 gated compressor/- lished by Writer's Digest Books, limiter uses high frequency pulse- 9933 Alliance Road, Cincinnati, OH width modulation techniques and 45242. Available from Polymart includes a noise gate function, for $12.95. LED gain reduction display, dual Another book, "Index to Alco­ mono/stereo mode, attack/decay hol, Drugs, and Intoxicants in controls, and VCA detector jack. Music", has been published by $400 list. Polyphony author Dr. Andrew Gelt. The A-8 1/4" eight track 471 entries, 59 page typescript, recorder has been reduced in price statistical data, vinyl cover. to $1995; a new model, the A-8LR, $15.50 ppd from Dr. Gelt at 10919 can record 8 channels simultane­ Fairbanks Rd. NE, Albuquerque, NM ously (the A-8 is limited to four 87112. simultaneous tracks) and lists for $2500. More monolithic filters. Na­ tional Semiconductor (2900 Semi­ Color Computer, meet music. conductor Dr., Santa Clara, CA DANS (13 Cedar St. Rm 130, 95051) has announced three inex­ Martinsburg, WV 25401) has an­ NED meets GR. The GR System pensive CMOS filters: the MF4, a nounced software on cassette for interface (developed for and used CMOS fourth-order Butterworth low the Radio Shack Color Computer in Roland's guitar synthesizers) pass filter; the MF5, a second (16K memory minimum) which gives has been accepted as the standard order universal (low pass, high it single-voice synthesizer capa­ by the New England Digital Cor­ pass, all pass, notch, bandpass) bilities. Notes are played on the poration. This means that NED filter; and the MF6, a sixth order upper two rows of keys; attack, will be using Roland GR series low pass filter. decay, sustain, and release are guitars to interface to their adjustable. The program supports Synclavier Digital Synthesizer, Reticon (345 Potrero Ave., pitch bending in both directions, thus opening up digital synthesis Sunnyvale, CA 94086) has an­ as well as vibrato and a "pitch- techniques to the guitarist. nounced the R5621, which contains bend-on-attack" feature for twang In other Roland news, the two second order filters in one effects. Jupiter-6 (retailing for $2,995) package; it creates a number of is a six-voice version of the useful filters, including ellipti­ New "Producer Series" pro­ Jupiter-8 (which recently has been cal and biquad types (it may also ducts. Yamaha has introduced the reduced in price from $6,495 to serve as a sine wave oscillator). MS10 powered monitor speaker (20 $4,995). It includes the MIDI The R5622 contains four second Watts RMS, 6.75" X 6.5" X 11"). interface. order filters in a 20 pin package. Suggested uses are for portable ------— ------* Po^phofly A p ril 1983 23 IEMA update. Don Slepian submitted the following: "The International Electronic Music Association held its 3rd annual convention on 11/13/82 at the Appel Farm Arts and Music Center in Elmer, NJ. In a beautiful, secluded theatre there were 6 hours of live electronic music featuring performances by the Atomic Thinkers, the Nightcrawl- ers, Doug Walker and the NYC Elec­ tronic Music Collective, Tom Mas- sapollo, and Lauri Paisley. Off­ stage records and tapes were ex­ changed and sold, technical se­ crets revealed, software traded, music debated, and many friend­ ships renewed. "Membership in the IEMA is open to anyone who plays or enjoys electronic music. The $12 annual fee brings the irregularly pub­ lished journal, SYNE, and connects Effect Switcher. JL Cooper New Lead Synth. The Syrinx

Electronics (2800 South Washington you to other synthesists in your lead synth from Synton (Box 83, area and around the world. Send Blvd., Marina Del Rey, CA 90291) 3620 AB Breukelen, Holland) offers name, address, and membership fee has introduced an Effect Switcher several unique features. The fil­ to Jim Finch, PO Box 456, Salaman­ capable of switching 14 effects ter section includes not only the ca, NY 14779." anywhere in the signal path. 64 usual 24 dB/octave LPF but also patches may be stored in memory, two resonant peak filters. A Software. Notable Software along with eight control voltages special "Touch 'N Bend" control (PO Box 1556, Philadelphia, PA and three switch closures, and makes for natural modulation con­ 19105) has released "Musical dumped to tape via cassette inter­ trol, and there are many modula­ Match-Up", an instructional music face. $2000; customized units tion options. Other features in­ game for the Apple II. No addi­ available. clude a ring modulator, noise tional hardware is required. Re­ generator, independent VCF and VCA quires DOS 3.3, Applesoft BASIC, SSM evaluation/voice board. envelope generators, two VCOs, and 48K RAM, one disk drive. $25 Solid State Micro Technology for a 3.5 octave keyboard! (educational discounts available). Music (2076-B Walsh Avenue, Santa Clara, CA 95050) has introduced the 5010 Synthesizer Board. It includes the board, two SSM2033 VCOs, SSM2022 dual VCAs, SSM2044 lowpass filter, SSM2022 state variable filter, two SSM2056 en­ velope generators, and two hard- to-find 1% resistors. There are also provisions for on-board LFO, noise source, and on-board regula­ tion. All controls, inputs, and outputs pin out separately to a standard 100 pin edge connection. More than one board can be used for polyphonic applications. Con­ tact the factory for pricing and availability.

Hear, hear! I never run a New linear IC process. Texas drill press, chain saw, or the Instruments has developed LinCMOS, like without ear protection — and which combines the low voltage, I think it really has helped pre­ low power, and high input impe­ serve my hearing. Some of the dance of CMOS circuits with low best ear protectors I've run offset and wide voltage swings. across are made by EAR Corpora­ The first two op amps of this tion, 7911 Zionsville Road, In­ series are the TLC251 and TLC271, dianapolis, IN 46268 (telephone which run off 1 to 6V supplies 317-293-1111). They can tell you (batteries, anyone?), have a slew the address of your local distri­ rate of 4.5V per microsecond, and butor . ------>

24 PtilyptttMiv April 198v3 background. quency generator. "Actually", This project took three said Curt, "this started out as a a noise figure of around 30 years, including an intensive col­ VCA. But we couldn't figure out nV/root Hz. While this spec is laboration between Douglas and Don how to compensate it, so what the not exactly low noise, the company Row, president of The Solid State hey" . anticipates lower noise figures as Semiconductor Company with the The DES/SSCLTEPEEG 3203 is the process is perfected. Longest Title on the Entire Planet packaged in a 48 pin dip with or Even the Entire Galaxy (SSCLTE- external cooling fins and a small The following press releases were PEEG). "Neither of us had suffi­ on-board nuclear reactor. Contact all received April 1st: cient resources to develop this either factory for details on New Recorders. TAEC (3377 chip independently", said Don. pricing and availability. Oersted Lane, Anaheim, CA) has "But the results are so encourag­ Homosapiens Electronics in­ introduced the 712, the first 12 ing we will be doing more together troduces Programmable Musician. track recorder which uses 3/4" in the future". HE,, manufacturers of numerous tape. "We saw a gap between 8 The multi-function chip in­ programmable instruments, has in­ track 1/2" and 16 track 1", so we cludes : troduced the TR-HS android. "We filled it" said Gimball Sprocket, • Programmable black noise noticed that real musicians get Director of Engineering. List generator, which provides a relia­ pretty bored just programming price is unavailable at press ble source of non-signals. stuff, pushing a button, and let­ time, as is 3/4" audio tape. • Clock generator. This is ting the machines play. After Fosstech (213 Capstan Drive, for when you want to know how much seeing an electropop concert where Otari, CA) has announced the Model time is left until the gig is the musicians fell asleep on stage C-9 nine track cassette recorder. over . while programmable instruments and Physically configured like a four • Micro processor. Shreds, tape tracks played on, we decided track, Fosstech squeezes out nine cuts, slices, and dices micros. there must be a solution. The TR- tracks by making one track carry • Uncommitted transistor HS is that solution", said Arthur sync information, while the re­ array. We asked if they were NPN Deetoo, director of Android Devel­ maining tracks have sounds multi­ or PNP, but they wouldn't commit opment. The android is also pro­ plexed on to them (3 sounds per themselves. grammed to call DJs incessently track) "at a real, real fast • Delay line. Unfortunate­ until a particular record gets rate". On playback, the sync ly, the introduction of this fea­ played, has road-worthy bionic track de-multiplexes the sounds. ture has been delayed, but both arms, speaks five languages in­ The recorder lists for $50; how­ Curt and Don claim the Rev 2 ver­ cluding Hip and Jive, and has a ever, the optional anti-aliasing sions will include this important limited warranty of three score filter network costs $2,750. feature. and ten years.------. "Musicians for Electronic • Uncontrollable radio fre­ Projects". Craig Anderton's first book written for electronic pro­ jects demystifies how musicians BY PROFESSIONAL DEMAND work. Effects learn how to beg DDC OFFERS FREE ADVICE, PERSONAL SERVICE for alkaline batteries, what to do AND ONE-DAY SHIPPING OF THE FINEST MUSIC if they're stuck with an owner who AND SOUND EQUIPMENT AVAILABLE ANYWHERE: uses acid core solder, and why they are sometimes kicked or ©CfOULin Lraynor hurled across the room. Includes K0RG pol^pcision illustrations and psychological profiles of 27 different types of KELSEY, j | | \ m m musicians. $10.95 from Android Press (40 Widget Street, Cincin­ ___ _ ( m x p ) iiv r nati, OH). New delay line. The ME-2 delay line from ME-2 Electronics ( f t ) © (1024 Photocopy Road, Similar- ville, MO) has a maximum delay of —! l|l REMO 1024 milliseconds, an output T O P C D M O YAMAHA balance control, a triangle wave C R UMA R

Polyphony A p ril 1983 25 Practical Circuitry through the switch to ground. The output is thus at ground as well. It used to be that there were Looking back at figure 1, lots of oldtimers who could do the with no voltage at the input of RI most marvelous things with vacuum the transistor is off and no cur­ tubes, but were totally out to sea rent flows. However, apply a My Favorite when it came to transistors. This voltage to RI and current will was simply a case of not keeping flow through the base-emitter up with the advances in technolo­ junction. By transistor action Transistor Circuits gy. But how about the reverse? this will cause current to flow Lots of people today seem to be from the power supply through the able to design all sorts of neat collector straight through to the things with solid state parts, but emitter and ground. The output is are lost when it comes to vacuum pulled to ground. Thus you can By: Thomas Henry tubes. And finally, let's carry see that the switch is inverting. this to the extreme. What about You may wonder how such a the person who grew up with inte­ simple circuit can be used. Well, grated circuits but can't design one of the most important uses is with either tubes or transistors? level conversion. Suppose the +15V I'm that way! I learned electron­ input voltage is TTL level (0 to ics by building things with ICs + 5V) and you want to interface to and somehow seemed to miss all of another circuit using a +15V power the basics of semiconductor supply. This circuit will do the theory. trick, since for a transistor with I suspect that there are lots a fairly high DC current gain (say of people who are in the same of 100 or so), the +5V signal will boat, especially among the younger be enough to turn the switch on. Polyphony readers. A couple of Hence, a +5V swing can trigger a years ago I decided to do some­ + 15V swing. thing about this gap in my know­ Another typical use is as a ledge, so I bought a number of simple inverter. Suppose in your self-study books on the subject. design you've used up all of the At the end of the article I men­ logic gates you had available, but >R2 tion some of these books if you S10K you need one more inverter. You want to do likewise. But for 1_____ o OUTPUT don't want to open up a new hex right now let's look at four of my inverter package and waste the favorite transistor circuits that five unused units. This is a 1 have found along the way. perfect time to use a transistor! I should probably mention And by the way, you can use just that in your own design work, most about any NPN transistor. I like ^ \ of the time you will want to use to keep a big stock of 2N3904s on integrated circuits. They are Fig.2 hand for this sort of application. usually very easy to use, make Figure 3 shows a non-invert­ + 15V circuit board design simple, and ing switch and figure 4 shows its will save you money. However, mechanical equivalent. Consider there are times when a transistor figure 4 first. When the switch circuit will fill the bill more is open, no current flows through closely. Cases of this might be the switch and therefore the out­ where you have only a single po­ put is at ground. However, close larity supply (most linear ICs the switch and current flows require a bipolar supply), need a through the contacts. The output heftier drive current than the IC then swings to full supply. , can supply, or need to use some By analogy, in figure 3 if no unusual characteristic of the voltage is applied to RI then the transistor (perhaps for exponen­ transistor is not conducting and tial or logarithmic conversion). the output is at ground. However, With this in mind, let's look at apply a voltage to RI and current four circuits where transistors flowing through the base circuit are ideally suited. will cause collector current to Figure 1 shows about the flow. A voltage drop will be simplest circuit you can design developed across R2 and this is with a transistor: an inverting the output. As you can see, this switch. It's hard to beat this is a non-inverting switch. A for simplicity and versatility. positive voltage on the input Figure 2 shows that when the causes a voltage to appear at the switch is open the output is at output. +15V, and no current flow through What's the use of such a the switch contacts. However, circuit? Once again, level con­ close the switch and current flows version comes to mind. But per-

26 Polyphony A p ril 1983 haps more importantly is the fact + 15 V + 15V that the circuit is really a buf­ fer. The input impedance of the circuit, as shown, is about 100k so that this shouldn't load down the driving circuit appreciably. However, the output impedance is about lk which can drive another, say, 100k source, with only 1 % loading. So you can see that the output drive current is quite good. And this is the purpose of a buffer! Figure 5 shows how we can take two of the inverting switches described above and cross-connect them to form an R-S flip-flop or latch. Can you see how Q 1, RI, and R2 form one of the switches we talked about above? And likewise, Q2, R3, and R4 form another Figure 5 also shows the truth Let's leave the digital world switch. The output of Q1 couples table for this circuit and you can and move on to the analog. Figure to the input of Q2 and the output see that this is the standard 6 shows one of my all time favor­ of Q2 couples to the input of Ql. table for an R-S flip-flop. Most ite transistor circuits: the (Symmetry like this always gives of the time you will want to use triangle-to-sine converter. Read­ me goosebumps!) Let's analyze the standard cross-coupled NOR gates ers of Practical Circuitry will operation. for this circuit. But as men­ remember this from the VCO Deluxe circuit presented some months Suppose that output Q is low. tioned above, occasionally you This implies that transistor Ql is just don't want to crack open a back. I'm going to get technical off and therefore Q bar (Q) is new set of gates to only use a for a moment so you can skip ahead to the next paragraph if you want; high. Q bar is in turn coupled to couple of them. Or perhaps the Q2, turning it on. Therefore Q is power supply is + 24V. CMOS or TTL but if you've had a smattering of low, confirming our original as­ won't work here;, but it's easy to calculus, the theory of operation

sumption. Now apply a brief logic find transistors that will work at is quite simple. Ql and Q2 form a one to the set input. This turns this supply voltage. Conclusion: differential pair. Normally for transistor Ql on and pulls Q bar sometimes it pays to think dis­ approximate linear operation the to ground. This in turn switches crete!

Q2 off and causes the Q output to + 15V OUTPUT OFFSET TRIM go high. Hence the outputs have R12 100K switched states. Note also that + 15V they will remain in this condition until a pulse is applied to the reset input. You can prove this to yourself by going through an analysis similar to the one given above for the set input.

SINE OUTPUT

TRIANGLE INPUT Q. i 5V

input to the pair (at the base of Ql) is kept quite low, say below 10 mV peak. However, for this application we will deliberately drive the input quite high. For a 5V peak input, R13 and R3 attenu­ Triangle to Sine Converter ate the signal to about 100 mV. Designer: Thomas Henry This is very high for a differen­ tial pair, and will cause distor­ All resistors in ohms tion. However, this kind of dis­ tortion is just what we want! Fig. 6 -15V

Polyphony A p ril 1983 27 Practical Circuitry..... R13 adjusts the drive voltage. of transistors too. More impor­ RIO soaks up some of the inaccura­ tantly, if you're like me and feel cies caused by mismatching of the uneasy working with them, I hope Consider the circuit to be a transistors. The output is a dif­ this will inspire you to learn transformation device. For a ferential type and so must be more. When I decided to correct triangle wave input (over a cer­ converted back to a single-ended my "deficient" background in tran­ tain range) it can be demonstrated operation for standard audio work. sistors I dug up two books and that the output will be a modified The differential output is taken conducted a self-study course of hyperbolic tangent (abbreviated off of the two collectors and is my own. These are Electronic tanh). You study these sorts of sent to op amp IC1. The op amp Circuits by D. Casasent (New York: functions in the calculus, but converts the signal to a single- Quantum Publishers, 1973) and what's important to us here is ended output with an amplitude of Electronics: A Self-Teaching Guide that the hyperbolic tangent is a 10V p-p. R12 adjusts the offset by H. Kybett (New York: John very close approximation to our so that the signal is symmetric Wiley and Sons, 1979). I have ordinary sine wave (over specific with respect to ground. never regretted looking into these ranges). This is all more techni­ You can trim this circuit up books; they're both recommended, cal than I want to get here, but quite easily with an oscilloscope, but Kybett is especially good, if you Vant to see the full mathe­ but don't neglect your ears! The since it is written for transistor matical derivation of this, refer human ear is an excellent distor­ tyros who know a little bit about to the excellent article by Bernie tion measuring instrument, so be electronics. And it's self-paced Hutchins ("Mathematical Analysis sure to listen to the signal while as well. The other book is an of Differential Amplifier: Trian- you tweak the circuit, even if you excellent "one-stop" reference for gle-to-Sine Converters", Electro- are using an oscilloscope. First anything transistor but is more notes, volume 9, number 82, Octo­ adjust R13 while watching the technical. Do yourself a favor, ber, 1977 , pp. 5-17). waveform for smooth transitions at read a good book this month! If you skipped the last para­ the peaks. Next trim RIO for graph let me summarize what was basic symmetry. You want the said there in one sentence: the positive excursions to look essen­ input to the device is a triangle tially like the negative excur­ I Q Q T T p , wave and the output is a curve sions. Finally, tweak up R12 for l h /% ..! JL*« which resembles the ordinary sine zero center. That's all there is wave very closely. Let's look at to it! A one chip A I)SR some of the circuit details. Writing this article was a The input should be a trian­ lot of fun for me, and I hope you gle wave with a 10V p-p amplitude. Poly-61 review enjoyed this trip into the realm & m ore— ... Musitech® - two special offers Memorymoog® Until June 15th, Moog® is offering a $100 rebate with the purchase of the Memorymoog. Musitech has set special pricing for this offer. Call for our best price.1 Soundchaser II® with Syscom® computer system A special package: the Passport Designs Soundchaser II® with Turbo Traks® 16 Track soft­ ware and Demo Disk included; the Syscom Apple® — compatible computer with Rana® Drive and interface card, NEC 1260 green phosphor monitor, a box of Elephant® diskettes, and a diskette storage file. This system is complete and ready to configure, at the very low price of $2550.00,2 shipping included. (This system is shipped UPS.)

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28 Polyphony A p ril 1983 Xhe Boss DR-55 is a versatile little drum box which resembles the PAIA Programmable Drum. How­ ever, one thing I didn't like is that the "rim shot" sound resem­ D r. Rh y th m bles a clave more than anything else. This may be fine for all the Bossa Nova fans in the audi­ ence, but chances are if you like to rock out a bit more some other sound would be more useful. This mod alters the clave to more of a tom sound. Begin by removing the bat­ teries (note that you'll lose any patches you've stored unless you can complete this modification in less than a few minutes, which is doubtful). Next, remove the four Phillips head screws located on the front panel, and pull off all five knobs. Then, unscrew the four Phillips head screws located on the front and rear lips of the case. Remove the front panel to expose the circuitry; note that the circuit board will fold back easily to allow access to the foil side of the board. Locate the parts in the im- mediate vicinity of the Accent control on the component side of the board, as shown in figure 1. This is where the action Modification is going to occur. The capacitors labelled "1" and "2" in the diagram are 0.0015 uF units. Replace them with 0.01 By: Craig Anderton uF mylar capacitors. Capacitor "3" is a 0.0022 uF unit and should also be replaced with a 0.01 uF mylar cap. Capacitor "4" (0.0022 uF) should be changed to 0.05 uF; finally, the capacitor marked "X" (a 0.0027 uF unit) should be re­ placed with a wire jumper (or, solder a short on the foil side of the board in parallel with this capacitor). Resistor "6" sets the overall level of the tom sound. 330k seems just about right, but feel free to experiment. Resistor "5" sets the resonance; I added a 1.8k resistor in parallel with "6" to increase the resonance somewhat. After you double-check your work, re-assemble the DR-55 in the reverse order of which you disas­ sembled it. Snap the batteries in place, patch to your amp, turn it on, and you're ready to go. ------• figure 1

P olyp h on y A p ril 1983 29 SOURCES IN By: David B. Doty Fundamentals of Musical Acoustics Arthur H. Benade New York: Oxford University Press, 1976. The study of acoustics and psychoacoustics is a pursuit which Benade, an Indian-born physicist and flute I strongly recommend to anyone in­ player, provides what I regard as the best and most volved in electronic- music. My comprehensive study of musical acoustics currently own experiences in this area, available to the layman. This book progresses in a while somewhat atypical, illus­ logical fashion from the simple to the complex, trate the value that knowledge of giving careful attention to details all along the the physics of sound can have for way. Equations appear only when necessary, and an an electronic musician. For a elementary knowledge of algebra should suffice for number of years prior to becoming the understanding of everything presented here. The involved with synthesizers, my material examined includes room acoustics, the human musical activities included, in voice, and all..of the major families of acoustic addition to composing and per­ instruments. Each chapter concludes with a number forming, the design, construction, of experiments that may be conducted with simple and modification of acoustic ins­ equipment, many of which can be quite revealing. truments for use in alternative tuning systems. In pursuit of these activities, I found it ne­ cessary to devote considerable

time and energy to studying the Horns, Strings, and Harmony A. H. Benade production, transmission, and per­ New York: Anchor Books, 1960. ception of sound. As a result, when I turned my attention to This book gets my recommendation as the best synthesizers, I readily understood and most easily understood introduction to the the functions of the various mod­ science of music. The subject matter covered in­ ules and had little difficulty in cludes the basic behavior of vibrating systems, the constructing effective patches. nature of the human ear and its effect on the per­ The vocabularies of acoustics and ception of music, and a simplified exposition of the electronic music are essentially law governing string and wind instruments. The the same. Since I was already style is conversational and non-technical, and no accustomed to thinking of sound in math is involved. terms of frequency, amplitude, envelope, and waveform, using a synthesizer to control these musi­ cal parameters presented little difficulty. I thought of writing about On the Sensation of Tone Herman Helmholtz one or more aspects of acoustics (English translation! New York: Dover, 1954.* for Polyphony, but it soon became Helmholtz, in addition to his work in optics evident that a thorough examina­ and physiology, played a major role in the creation tion of even one topic in this of the science of musical acoustics. He is espe­ field would require more space cially known for his work on combination tones and than this magazine could provide, his attempts to establish a scientific basis for and that I would, at best, be consonance and dissonance. In addition to his con­ duplicating information which was clusions in these areas, this book contains informa­ already available elsewhere. As a tion on the physiology of the ear, vowel sounds, and result, I decided that the best tones generated by pipes and strings. approach would be to share with The appendices in the English translation, by you some of the sources that I Helmholtz's British contemporary, Alexander J. El­ have found most valuable in my lis, run to nearly 200 pages, containing extensive studies of acoustics and psycho­ information on tuning and temperament and on the acoustics. If you are new to experimental keyboards of the 19th century. Taken synthesis, reading some of this as a whole, this book is like a great dusty attic. material can help to ease your way It contains many valuable treasures, hidden among through a maze of unfamiliar equally many historical curiosities; a patient and ideas. Even if you have had ex­ discerning investigation is required to distinguish tensive experience in electronic between them. music, you may find that it sheds new light on familiar phenomena.

30 Potyphony A p ril 1983 re -v ie w

continued from page 11 ..... technical proficiency often seems ACOUSTICS to get in the way of the joy of music, but somehow this group managed both. Music, Physics, and Engineering Harry F. Olson Cluster Sowiesoso (Sky 005; New York: Dover, 1967.* 1976). My continuing favorite among their series of lazy summer This is a dense and presumably comprehensive afternoon music. work, touching on every aspect of sound generation and reproduction. Full of charts, tables, and equa­ Jack Ni t ? s che "Performance" tions, it is more valuable as a reference work than Soundtrack (Warner Bros. 2554; for cover to cover reading; just the thing if one needs to know, for instance, the relative frequen­ 1970). Oh I know, it's spotty -- cies of the modes of vibration of a clamped circular in places quite bad. But I love plate. The chapters on electronic music and record­ the movie and for 1970 the synthe­ ing are quite dated, with a considerable section sis is killer. being devoted to the RCA synthesizer. Peter Baumann Trans-Harmonic Nights (Virgin 2124; 1979). Genesis of a Music Harry Partch Everything about this album gets New York: Da Capo, 1974. classier every year. It cuts a clean profile — sonically, musi­ Although this is not, strictly speaking, an cally, graphically, artistically. acoustics text, I include it here for several rea­ sons. First, it does include detailed information Vangelis China (Polydor; 1979). on the history of tuning systems and on the age-old I still like his, oriental impres­ debate as to the nature of consonance, from the sions better than his sound track ancient Greeks and Chinese to the mid-twentieth work. Good sonics too. century. Beyond this, Genesis of a Music is the musical autobiography of a highly individualistic Syrinx Long Lost Relatives (True American composer, musician, and instrument builder North 5; 1971). Canada's claim to whose work should be familiar to every D. I. Y. electronic fame. The sound was musician. This book has been a major influence on theirs alone, the tunes memorable my musical life. and the audience...silent.

Steve Tibbetts Yr (Frammis 1522- Introduction to the Physics and Psychophysics of 25; 1979). Everyone who is con­ templating releasing their own Music Juan G. Roederer record should get this one first New York: Springer Verlag, 1975. — if only to see how it's done. This book, unlike the others cited above, con­ centrates primarily on psychoacoustics. That is, it is concerned with the way sound is processed by the ear and the brain, as opposed to the physical phe­ nomena that are its origin. This is a very detailed little book, dealing extensively with the physiology of the ear and the central nervous system and their continued from page 11 roles in the perception of music. Topics include discrimination of pitch and loudness, perception of SUBSTITUTION PROBLEMS simple and complex tones, and the relative impor­ tance of spatial and temporal cues in current I recently built your key­ theories of consonance. board preamp (see page 8 of "Craig Anderton's Keyboard Articles" -- ed.) and used an LM324 instead of Those books marked with an asterisk (*) are the 4136. Even at low amplifica­ available through Polymart, but you may have some tion, the output signal is heavily difficulty in finding the other books mentioned distorted, and the LED does not above. Do not despair; large public libraries and flash with this clipping. I am college music and physics libraries are good sources also interested in using this to investigate. If your local libraries don't have preamp to drive headphones. What what you need, they can probably obtain it for you. modifications should I make? Ask your reference librarian about the possibility of an inter-library loan Terrance Stewart Houston, TX ...... continued on page 38

Fotyphofty A p ril 1983 31 Meet S ID 6581 Sound Interface Device SYNC/RM

TONE OSCILLATOR/ WAVEFORM GEN.1 By: Janies Lisowski ENVELOPE GENERATOR 1

SYNC/RM

D TONE A OSCILLATOR/ T A WAVEFORM GEN. 2 Mleet the new kid on the ly-tempered music scale. With block, SID. SID (also known as proper use of the LO Frequency F F the Commodore MOS Technology 6581 Register, most any micro-tonal E ENVELOPE R Sound Interface Device) is an value in this range may also be S 3 GENERATOR 2 amazingly powerful, microproces­ obtained. (The frequency resolu­ sor-compatible single chip sound tion is limited by the amount of SYNC RM generator/processor. While de­ frequency change per single bit TONE signed to be interfaced with mini­ change in the control value. How­ 3 OSCILLATOR/ mum additional hardware to MOS ever, by changing the clock rate WAVEFORM GEN. 3 Technology's 6500 line of micro­ AND the register value, any fre­ processors (such as the 6502 found quency in this 4 KHz range could in Apple, Atari, etc. computers), be created. Even if the clock is ENVELOPE the SID should also be easy to not altered, though, the 16 bit GENERATOR 3 connect to any other 8 bit micro­ dynamic range allows frequency processor. The simplest way to sweeps or portamento without dis­ meet SID would be to obtain the cernible steps.) That's not bad Commodore 64 computer, which uses latitude, even if these three SID as its audio effects center. voices were just the ordinary Whatever your interest — good square wave you might expect from computer sound effects or a dedi­ a digital circuit; but they're not cated audio synthesizer — SID has just square waves!

a lot to offer. Each SID voice may be one of 6581 SID BLOCK DIAGRAM Oscillator capabilities. SID four different waveforms, as se­ has three independently controlla­ lected by the bits placed in the ble Oscillators (also called Control Register. Triangle, saw­ Voices). Since SID is a digitally tooth, pulse (or squarewave), and controlled device, the frequency noise waveforms are available. If afforded by combining the HI and ranges of the oscillators are you choose more than one waveform, LO Pulse Width registers (creating determined by the microprocessor's the result will be the logical AND a value similar to that of the clock speed and the value of the of the selected waveform, creating Frequency registers), a desired Oscillator Frequency Control Re­ a waveform of even greater com­ pulse width or duty cycle may be gisters. For each Voice, SID has plexity. As discussed previously, defined for the pulse waveform. A two 8 bit wide Frequency Regis­ the frequency of each waveform may linear range of duty cycle values, ters, HI and LO, each of which may be controlled via the Frequency from constant DC to squarewave hold a decimal number in the range Registers, with higher values giv­ (including all values between 0 of zero to 255. The HI and LO ing higher pitches. The noise and 50% duty cycle), will give the Registers respectively act as waveform is a random signal. pulse wave a "thinner" or "thick­ coarse and fine frequency con­ Changing the "frequency range" of er" character. The pulse width trols, with 256 steps of the LO the noise waveform alters the range may be swept without dis­ register being equal to 1 step of proportion of its high and low cernible steps. the HI register. With their com­ frequency components, yielding any ADSR capabilities. While a bined values, these registers pro­ noise character from the rumble of good command of frequency and vide a 16 bit digital oscillator thunder to the hiss of steam. noise content is essential to frequency control range. At the In addition to a basic fre­ realistic sound synthesis, overall suggested 1 MHz clock speed, this quency change, there are some timbre is even more important. oscillator range is zero to 4 KHz, other options for the pulse wave­ And, would you believe that this or 8 octaves of the normal equal­ form. With the 12 bits of control chip has full ADSR capabilities to

32 PofyplHmy •April 1983 a few more features that help it A4A3 A2 A1 AOC5RW02 RES leave the others far behind. For instance, the Control Registers have a Sync bit that, when set, A yglyvU ?- synchronizes the fundamental fre­ quencies of any two oscillators Chip Access Control for the much desired harmonic Hard Sync effect found in modern syn­ thesizers. A similar Control bit is the Test bit, which, when re­ set, causes the selected waveform to start from its zero level. Not only is this an exact method of synchronization, but, under the guidance of proper real time soft­ ware, enables the subtle influ­ ences of complex phase or frequen­ cy modulation. Such abilities could re-create the fine charac­ teristic changes found in the first few waveform cycles of some natural musical instruments; these changes are exceedingly difficult to synthesize with any other meth­ od. Another Control bit causes one oscillator to be ring modu­ lated by the frequency of another oscillator. This technique can produce non-harmonic, gong-type sounds. Like ring modulation, two of SID's register level features also mimic their analog synthesiz­ er counterparts in digital format. The Osc 3/Random and Env 3 Registers are byte sized windows into Oscillator 3's world of pass­ ing numbers. By reading the val­ ues in these registers, the com­ puter (or human) is able to follow the rise and fall of the third Oscillator waveform or envelope. If the Osc 3 Waveform was, for example, a low frequency triangle wave, the Random Register would present a series of slowly in­ creasing, then decreasing, numbers POT Y POT X EXT IN (representing the instantaneous amplitude of the triangle waveform as it cycles). If the computer took this value and placed it into handle that! the Frequency Register of some SID's Attack/Decay and Sus- may be held indefinitely at the other oscillator, the effect would tain/Release Registers provide an sustain level if desired, and be frequency modulation (or exponential response (the kind our multiple Gate changes will cause sweeps) of that Oscillator by the ears react to), in the way that a attack and release sequences that waveform and frequency of Oscilla­ sound effect's loudness builds up can create very complex amplitude tor 3 — just like the LFO modula­ to a maximum level (attack), falls envelopes. An additional 4 bit tion in an analog synthesizer. If from that level (decay), sustains (16 values) Volume register may Oscillator 3 was set to the Pulse at some lesser level, and then is also change the total audio output waveform of varying duty cycle, released so that it fades away. volume (the combination of all the result would be pulse width Four bits (16 possible values) for three voices) from mute to full modulation (PWM). If a noise each parameter allow a range of 2 volume. Altering the volume can waveform is used, the effect will milliseconds to 8 seconds for A/D, modify the magnitude of the ADSR be that of random sample-and-hold. and 6 milliseconds to 24 seconds levels or provide amplitude domain Likewise, the Env 3 Register will for S/R times. Each of the three effects, such as tremolo. represent the values of Oscillator voices may have its own unique SID's accessories. With all 3's ADSR cycle. Applying this ADSR values. Each voice's ADSR of these possible combinations of information to some other voice cycle may be initiated (triggered) voice and timbre, SID is more than would simulate an analog envelope or terminated via a Gate bit that an even match for some of the follower. is located in that voice's Control other sound chips in terms of Register. Musical notes or sounds versatility. Even so, SID boasts >

Fotyphony A p ril 1983 33 TYPICAL SID CIRCUIT

SID's filter. Some audio pass or 12 dB/octave high pass. tered, then sent to a single audio

integrated circuits are sound Any combination of the filter output (which is governed by a sources, some are sound processors modes can be used; for example, master volume control). The but SID is both. Two Regis­ combining LP and HP responses ability to take an external audio ters, FC HI and LO, wh'en combined, produces a notch response. Of signal, then filter and/or alter produce an 11 bit number that course, sweeping the resonance or the timbre (via the volume regis­ defines the linear range of cutoff center frequency values through ter) under real time computer or center frequency values for a their ranges with a sound source control has great potential for digitally programmable audio fil­ present will give the expected some astounding sound or scienti­ ter. Using the suggested 2000 pF "swoosh" or wa-wa effects. fic uses. capacitor results in a cutoff Which sound sources can be Speaking of control, there frequency range from 30 Hz to 10 filtered? Three bits in the Res/- are two more SID control points of KHz. The 4 bit Res/Filt register Filt Register select any of the note, especially if you don't like may take one of 16 values to de­ aforementioned voices, but best of to push buttons! These are the termine the amount of resonance or all, a 4th bit selects an external POTX and POTY pins, which act as "peaking" of frequencies at the audio input. This option is what analog to digital converter (A/D) filter cutoff frequency. The bits really gives SID the edge over its inputs. With +5V DC, a capacitor, in the Mode/Vol Register determine brethren. Any combination of gen­ and resistor (potentiometer) con­ the type of filter mode: 12 dB/- erated sound voices and external nected to POTX and/or POTY, a octave low pass, 6 dB/octave band­ control may be combined and fil­ register value (0 to 255) propor-

34 Pofyphoret' A p ril 1983 SID CONTROL REGISTERS

There are 29 eight-bit registers in SID which control the generation of sound. These registers are either WRITE-only or READ-only and are listed below in-Table 1.

ADDRESS REG # DATA REG REG AA A3 A2 A1 AO (HEX) D7 D6 D5 DA D3 D2 D1 DO NAME TYPE VOICE 1 0 0 0 0 0 0 00 F7 ^ 5 ~n— "TO---- FREQ L0 WRITE-ONLY 1 0 0 0 0 1 01 F15 F1A F1 3 F12 F1 1 F10 1-9 F8 FREQ HI WRITE-ONLY 2 0 0 0 1 0 02 PV/7 PW6 PWq PWA PWq Ttf2 Twi PWo PW L0 WRITE-ONLY 3 0 0 0 1 1 03 - - - - PWl 1 ’Win PWq pwp, PW HI WRITE-ONLY k 0 0 1 0 0 0A NOISE TEST w SYNC GATE CONTROL REG WRITE-ONLY 5 0 0 1 0 1 05 ATKq ATK2 ATKl ATKo DCYq DCY2 DCY1 DCYo ATTAC-K/DECAY WRITE-ONLY 6 0 0 1 1 0 06 STN3 STN2 STN1 STNq RLS3 RLS2 RLS1 RLSq SUSTAIN/RELEASE WRITE-ONLY VOICE 2 7 0 0 1 1 1 07 F7 F6 F5 fa Ft F 2 M “To— FREQ L0 WRITE-ONLY 8 0 1 0 0 0 08 F1 5 F1A F n F1 2 F11 F10 F9 “T 8- FREQ HI WRITE-ONLY 9 0 1 0 0 1 09 PV/7 PW6 PWq PWA PWq PV'2 PWi PWo PW L0 WRITE-ONLY 10 0 1 0 1 0 0A - - - - PWl 1 PW10 PWq PWp, PW HI WRITE-ONLY 11 0 1 0 1 1 0B MG I S E TEST m b SYNC GATE CONTROL REG WRITE-ONLY 12 0 1 1 0 0 OC ATK3 ATK2 ATK1 ATKO DCY q DCY2 DCY 1 DCYo ATTACK/DECAY WRITE-ONLY 13 0 1 1 0 1 0D STN3 STN2 STN1 STNo RLSq RLS2 RLS 1 RLSq SUSTAIN/RELEASE WRITE-ONLY VOICE 3 WRITE-ONLY 1A 0 1 1 1 0 0E F7 F6 __F 5 FA F 7 F2 F1 F0 FREQ LO WRITE-ONLY 15 0 1 1 1 1 OF F1 5 F1 A F1 3 F12 F11 F10 F9 F8 FREQ HI 16 1 0 0 c 0 10 PV'7 PU6 PWq PWA PWq PV.'2 PWi PWo PW L0 WRITE-ONLY 17 1 00 0 0 1 1 1 - - " - PWi i PW10 PWg PWg PW HI WRITE-ONLY 18 1 0 0 1 0 12 NOISE TEST SYNC GATE CONTROL REG WRITE-ONLY 19 1 0 0 1 1 13 atk3 ATK2 ATK1 ATKo DCYq DCY2 DCY1 DCYo ATTACK/DECAY WRITE-ONLY 20 1 0 1 0 0 1A STN3 STN2 STN 1 STNo RLS 3 RLS2 RLS i RLSo SUSTAIN/RELEASE WRITE-ONLY FILTER 21 1 0 1 0 1 15 - - - - - FC2 FC, FC L0 WRITE-ONLY 22 1 0 1 1 0 16 FC1 o FCc FCp fc7 FC6 FCq FCA FC 3 FC HI ! WRITE-ONLY 23 1 0 1 1 1 17 RESq RES2 RES 1 RES0 FILTex FILTq F I LT 2 FI LT 1 RES/FILT WRITE-ONLY 2A 1 1 0 0 0 18 3 OFF HP BP LP VOL3 V0L2 V0L1 V0L0 MODE/VOL WRITE-ONLY MISC X 25 1 LT, ftxi; ~TXq------"FX — PXo P0TX READ-ONLY 1 0 0 1 19 ~ ^ 7 ~ "T*T .... T * 2 1 26 1 1 0 1 0 1A PY7 PY6 PY5 PYA PY3 PY2 PY1 PYo P0TY READ-ONLY 0SC/RAND0M READ-ONLY 27 1 1 0 1 1 1 B 07 06 0 5 0 A 03 02 01 00 28 1 1 1 0 0 IC E7 F6 f 5 EA F3 ^2 h to ENV3 READ-ONLY

TABLE 1 - SID REGISTER MAP

tional to the resistance setting (The 64K of RAM memory, great VIC great 6 string guitar synthesizer. of the potentiometer may be read video graphics, joystick, and Need I mention the straightforward by the computer, and subsequently other irtterface ports are useful digital mono/poly/portable key­ used as control or data informa­ too!) But you don't have to use board synths? Did I hear someone tion. Since the value from this the Commodore 64K; by now, I'm say "speech synthesizer"? input is updated every 512 clock sure you'll agree that a SID and SID, I think you made some cycles, it may not be fast enough any computer would make beautiful new friends! for speech processing, but should music together. be more than adequate for use with As raw material, the 6581 a synthesizer front panel control Sound Interface Device combines Parts Availability knob or 2 axis joystick input the best in additive (oscillator) control. and subtractive (filter) synthesis The Commodore MOS 6581 SID Another thing to note is that with digital control value. It's (Sound Interface Device) is avail­ the SID External Input and Audio not an understatement if I say able from Falk Baker Associates, Output should be capacitor cou­ that when using the SID as a com­ 382 Franklin, Nutley, NJ 07110 pled, and that the signals are 3V ponent in a larger audio system, (telephone 201-661-2430). Price p-p maximum and ride on a 6V DC your imagination will be chal­ is $17.50 plus $1.50 postage. For bias level. lenged by Commodore MOS Technolo­ data, try MOS Technology Inc., 950 As a Commodore 64 computer gy's design. As some examples, Rittenhouse Rd., Norristown, PA owner, I am delighted that its just consider the filter applica­ 19103. design includes a plug connection tions for guitar effects, digital for SID's direct audio output and recording front ends, or vocoders. external input so that I can get And I'm sure more than one person Legal corner: Apple, Atari, Com­ out high quality sound (and pro­ came up with this equation: (3 modore, and MOS Technology are all cess an audio input), without voice oscillator ADSR) + (3 voice trademarks of their respective having to modify the computer. oscillator ADSR) + computer = 1 companies. 0

POtyphoi^ A p ril 1983 35 shifting for the triangle wave output. Q3 accepts a synchro-sonic reset trigger to reset the LFO, which is a very powerful feature. The VC LFO accepts a standard +15V power sup­ ply. Note that the 2209 is treated like a single- supply device running from +15V. This is important, since the device cannot accept 30 Volts across its supply terminals. You can use just about any kind of op amp for IC2-IC4. A FET input type would probably be more precise, but we're aiming for low cost so you might as well use a 741 or whatever else is handy. The one concession to accuracy is C4 and C5. I would suggest using tantalum (rather than more easily obtainable electrolytic) capacitors for best fre­ quency stability.

Calibration. Calibrating the VC LFO can be easily done with a VOM or 'scope. First, ground the control voltage inputs, then hook your meter or 'scope probe to pin 8 of IC1, and make sure that SI is in ,the triangle wave position. Next, adjust R18 so that the circuit just kicks into oscillation. This will be a very slow frequency, so watch your meter or scope trace carefully for signs that the LFO is coming to life. Now feed a +10V control voltage into the CV Log Response input, and adjust R14 for the highest possible fre­ quency. Note that when you get past a certain point, the frequency will actually decrease, or perhaps become erratic. Voltage Controlled LFO You want the highest frequency short of this erratic point. Finally, clip your probe to IC4's output. If you're using a VOM, the following calibration will By: Craig Anderton be somewhat difficult since you'll have to set the LFO for a low frequency to minimize meter "over­

W e all know about the advantages of voltage shoot". A 'scope is a better choice for this part of the calibration. In any event, adjust R19 for a controlled, exponential response VCOs. What is less 10V peak-to-peak output, then adjust Rll so that the well known are the advantages of voltage controlled, bottom tip of the triangle wave touches ground, and exponential response LFOs — especially when dealing the peak reaches +10V. The VC LFO is now calibrat­ with wide-range LFOs. Exponential response LFOs have a smoother sweep than the linear variety, and ed . are more "natural-sounding" from a musical stand­ Using the VC LFO. There's not much too it — point . choose either the triangle or sawtooth output with The "Hyperflange + Chorus" takes one approach SI (note that the square wave output is available to an*exponential response VC LFO. That application simultaneously), apply a suitable voltage to the CV called for a wide-range, voltage controllable LFO, input to set the operating frequency, and you're capable of producing unusual waveforms specifically ready to go. The sync input, compatible with the suited to delay line applications; the CEM3340 was a "Master Synchronizer" PAIA module I described in the perfect chip for this circuit. However, what if you February 1983 issue of Keyboard magazine, resets the only need a "utility" log response LFO? For less LFO upon receiving a sync pulse in the range of +5 critical applications, a super-precision, expensive to +10V. This is handy for synchro-sonic tech­ chip like the CEM3340 would be overkill. niques, such as rhythmic vibrato. This article covers an exponential response VC LFO based on Exar's inexpensive, and widely avail­ That's all there is to the VC LFO. It's inex­ able, XR2209. It generates square and either trian­ pensive, useful, simple to build, and most of all, gle or sawtooth waveforms, accepts a standard 0 to it has a smooth exponential response which is mu­ +10V control voltage input, and delivers a standard sically useful. 0 to + 10V output. Acknowledgement. I'd like to thank Ron Dow for How it works. Figure 1 shows the schematic. turning me on to the XR2209, and for showing me the IC1 provides the basic waveform generation function; exponential control cell built around IC2. IC2 provides the exponential control response; IC3 is a control voltage mixer; and IC4 provides level

36 Polyphony A p ril 1983 C2

figure 1

VC LFO Opamp power supply connections assumed Power supply =-15v. © = 15 V. Q1 -Q3 : 2N3904

Parts List

Resistors (5% or 10%, 1/4 Watt) Capacitors Semiconductors RI, R2 470 Ohms Cl 100 pF D1 1N914 or equiv R3, R4 lk C2 0.01 uF IC1 XR2209 VC0 R5 4.7k C3 1 uF electrolytic IC2 - IC4 741 (see text) R6 - RIO 10k C4, C5 2 uF tantalum Q3 2N3904 RI 1 10k trimpot Q1 - R12, R13 22k Mechanical parts R14 50k trimpot R15 - R17 100k SI SPDT switch R18, R19 100k trimpot Misc. Jacks, circuit board, etc. R20 120k

Polyphony A p ril 1983 37 EOUIPfTEnT EXCHRDGE

continued from page 31 PUT POLYPHONY TO WORK FOR YOU. List equipment for sale or trade, Terrance — If you're going job openings, positions wanted, etc. Equipment exchange to substitute op amps, you have to classified rates for individuals offering goods or services for be careful. First, the pinout of sale or trade: 25c per work, 20 word ($5.00) minumum charge; the two parts is different; if you Commercial establishments: 50c per word. Prices, zip, phone didn't take this into account, numbers count as one word each. DISPLAY CLASSFIED: $15.00 per inch, one inch minimum, camera ready art to be supplied by there could be problems. Also, advertiser. All classified advertising must be prepaid. the 324 is designed for single Advertisers using a post office Box number for responses must supply operation, while the 4136 furnish Polyphony Publishing Co. with a complete street address works off bipolar supplies. Power and phone number. Readers should respond directly to advertiser. supply hookups are also different Polyphony is not responsible for claims made in ads, or for the for the two chips. Always use the results of any transactions. Polyphony reserves the right to edit or refuse any ads submitted. parts specified for a project unless you really know what you're doing. As far as driving head­ phones, most op amps will drive high-sensitivity headphones, but the volume level will not be over­ music equipment B Recordings whelming.

Synthi-AKS with velocity KEY ESSENTIALS cassette by Bill GUITAR WIRING TIP sensitive keyboard (DK-1) and Rhodes. Polys, Piano, and Pipe sequencer keyboard. In excellent Organ in a "Symphonic" Genre. I'm a radio announcer as well condition with extensive manuals $6.00 to Jazzical Records, Suite as being an active musician and and schematics. A rare and "A", 1392 N. Killian Dr., Lake Park, FL 33403 recordist. Something that guitar versatile instrument $1,250. Electro-Harmonix Vocoder - Rack companies ought to pick up from mount, sounds great, $300. the radio and recording industry is the use of two-lead shielded Walter Whitney (314) 429-2858. 1,000,000 SOUNDTRACK/CAST LPs! cable as the audio run inside Catalogue — $1.00. RTSP, Box bodies. You've seen the stuff; 10687, Costa Mesa, CA 92627. it's commonly used for low impe­ ROLAND TR-808 programmable drum soundtrack Value Guide — $5.50. dance audio line, and is great for machine. Excellent condition, Original Cast/TV Value Guide — guitar electronics. With that complete with manuals. Cost $5.50. Personalities too! cable, loss is minimal, adding a $1,100, sell for $600. David phase switch is a breeze without Shumate, 4267 N.E. 124th St. messing around soldering tiny Seattle,, WA 98125 (206) wires to shield jackets, and with 362-3239. a little ingenuity, you could add I I • ■ a dual ganged pot (hot and ground £ ★ ★ ★ n o w ...... leads reversed with respect to ON C60 CASSCTTt: each other) to create a classy ROAD KEYBOARD, Phianger, and many ELECT RON I C MUSIC little phase mixer. Next time you PAIA 2720 series modules. Some ■ ■ If you like the ityle of Larry § need to re-wire a guitar, take a work, some don't. Write for g ■ Fast and Pat rick G lee s o n ; g crack at this stuff. I'm having a details: Tom Marohn, 329 LaVeta g ball with it. J Try the tty 1 * ofl : Pass St., Golden, CO 80401 SYNTHETIC FOUR g ■ S $4.95 (o------g g A1 Peterson Steve Meeh 1 e d e r g Huntington, MA • g : i 6 i o J Ave NE g g g * Cedar Rap id s, 1A 52402 g

JnA-nJ J ITivrrpir I N L)IhJ\.

Dickstein Distributing Co...... 25 PGS Electronics ...... • 39 Gentle Electric ..... PAIA Electronics * * • 2* 4, 5j 40 on oi oo Jensen Tools ...... 5 POLYMART ...... 20, 21, 22 g Larson Music Co...... 15 Telex ...... Musitech ...... 28 Unique Vinyl ...... b

—

3 8 Polyphony A p ril 1983 LINEARS RESISTORS 5 % , 1/4 watt SIGNAL DIODE T L 0 6 1 ...... B iF e t...... 72 All EIA values available from 2.0 ohm to 5.1 Meg. 601-60... 1N914 (1N4148) signal diode . 5/.35 T L 0 6 2 ...... Dual BiFet...... 99 Also availble is 10 Meg. T L 0 6 4 ...... Quad BiFet...... 1.95 TRANSISTORS T L 0 7 1 ...... B iF e t...... 65 100 each of sam e v a lu e ...... $1.50 2N 3 9 0 4 .... 2N3904 NPN Transistor...... 25 T L 0 7 2 ...... Dual BiFet...... 1.15 50 each of sam e v a lu e ...... 98 2N 3 9 0 6 .... 2N2906 PNP Transistor...... 25 T L 0 7 4 ...... Quad BiFet...... 1.95 25 each o f sam e v a lu e ...... 75 N E 555...... T im e r...... 39 10 each o f sam e v a lu e ...... 40 POTENTIOMETERS N E 570...... Compander...... 3.80 5 each o f sam e v a lu e ...... 25 (3 /8 long shaft, 5 /1 6 mounting hole) N E 571...... Compander...... 2.95 8 5 4 -4 0 1 ...... 10K Linear taper ...... 1.09 N E 572...... Compander...... 4.95 ASSORTMENTS 8 5 4 -5 0 1 ... 100K Linear taper ...... 1.09 U A 741...... Comp. OpAmp ...... 29 10 each o f 10 values (1 0 0 )...... 3.00 8 5 4 - 5 0 5 ...500K Linear taper ...... 1.09 M C 1456.... .Low Noise OpAmp ...... 90 25 each of 10 values (250) ...... 6.50 o .... 1.48 8 5 5 - 4 0 1 ...10K Audio taper...... 1.09 R C 1556..... Low Noise O p A m p ...... 50 each of 20 values (1000)...... 16.00 C A 3 0 8 0 ...... OTA ...... 94 8 5 5 -5 0 1 ...... 100K Audio taper ...... 1.09 C A 3 2 8 0 ...... Dual O T A ...... 1.98 8 5 5 - 5 0 5 ...500K A u d io ta p e r ...... 1.09 CHORUS/DELAY KIT R C 4136...... Quad O p A m p ...... 1.10 8 5 6 - 4 0 1 . 10K Audio taper with This chorus/delay unit, designed by Craig Anderton Q. R C 4739...... Dual Low Noise ...... 1.19 pn/off switch ...... 1.25 N E 5532..... Dual High P ert ...... 3.70 and featured in Guitar Player magazine, provides flanging, slapback echo, and automatic double N E 5534...... High Performance ...... 2.65 tracking effects. The delay range is from 2 ms to 80 TRIM POTS (vertical mount) ms. Due to the use of compression and expansion 8 0 2 -2 5 1 ...... 250 ohm trimmer...... 40 SPECIAL PURPOSE techniques, the unit has dead-quiet operation up to 8 0 2 -1 0 3 ...... 10K trim m er ...... 40 □ □ S A D -1024...... A n alog D e la y ...... 17.50 about 50 ms and only m inim al noise out the full 80 ms. S A D -4096...... A nalog D e la y ...... 37.50 This project kit consists of all electronics, pots, jacks, MINI TOGGLE SWITCHES etc. Also included are the two circuit boards (etched, M K50240...... Top O ctave D iv...... 5.95 403-20....SPDT (on/on) sub-mini (3A).... 1.20 SN 76477...... S ound G e n e ra to r...... 3.45 drilled, and legended) needed for the project. Not included is wire, solder, case, knobs, etc. The 403-40....DPDT (on/on) sub-mini (3A)__ 1.50 Chorus/Delay unit also needs a well regulated 405-10....SPST (on/off) bat handle (6A). 1.85 SANYO HYBRID POWER AMPS bi-polar 15 volt power supply (not included). (A S T K 0 5 0 ...... 50 Watt Power Am p ...... 19.40 punched and legended rack mount panel will soon be LEDs S T K 0 7 0 ...... 70 Watt Power Am p ...... 24.20 available for this project.) Please note that the typical DC forward current (l-fwd) Order KT-CD777...... $78.00 SSM- SOLID STATE of these LED's is less than those offered elsewhere MICRO-TECHNOLOGY making these LED’s ideal for battery circuits or others “SNARE + " DRUM VOICE KIT where current consumption is a factor. SSM 2 0 1 0 .....V C A ...... 7.50 This percussion synthesizer was designed by SSM 2 0 1 1 ...... P re A m p ...... 5.75 Thomas Henry and appeared in POLYPHONY 305-201.....Red T-1% jumbo diffused (20 ma.)...... 30 SSM 2 01 2.....V C A ...... 9.50 magazine. Here's what Craig Anderton had to say 305-202.....Green T-1% jumbo diffused (30 ma).. .40 SSM 2 02 0.....V C A ...... 7.50 about the "SNARE + ” . "At last - an inexpensive drum 305-203.....Dual T-1% jumbo diffused (50 ma)...... 90 SSM 2 02 2.....V C A ...... 7.50 voice that has a punchy, full sound...... All in all, the SSM 2 0 3 0 ...... VCO ...... 7.50 Snare + delivers a lot of drum sounds, and I would 305-204.....Tri T-1% jumbo diffused (20 ma)...... 1.50 SSM 2 0 3 3 ...... V C O ...... 10.00 unhesitatingly recommend it to anybody who’s tired Note: 305-204 is a three lead, tri-color (green, red, SSM 2 0 4 0 .....V C F ...... 7.50 of the thin sound found in most electronic drum yellow) device. It is essentially two separate LED’s in SSM 2 0 4 4 .....V C F ...... 7.50 units.” one package. (The yellow is obtained by turning on We offer the kit with or without a panel. Kit 3770 both green and yellow.) SSM 2 05 0...... V C T G ...... 7.50 contains all electronic parts, switches, jacks, pots, SSM 2 05 6...... V C T G ...... 5.75 etc, as well well as etched, drilled, and legended a circuit board. Kit 3772 includes all this plus a punched JACKS and PLUGS and legended rack mount panel (standard 1 3/4 by 19 1 /4 In. PHONE JACKS u THERMISTER (Temp. Sensing Resistor) inches) available in black or blue (both with white legends). 901-101...Mono standard phone jack ...... 45 T S R -Q 81....Tel Labs Q81 1k ...... $3.50 Not included with either kit is wire, solder, mounting 901-103...Mono with n/closed contact...... 52 hardware, etc. The SNARE + also needs a bi-polar 15 901- 105...Mono end. jack (open back)...55 OPTO-ISOLATOR volt power supply (not supplied). 902- 211...Stereo standard phone ja ck ...... 70 CLM6000....Clairex CLM6000 ...... $2.85 KIT 3770 Basic SNARE + kit...... $33.95 902- 213...Stereo end. jack (open back).. .77 CAPACITORS (25 volt) KIT 3772 SNARE + with rack panel... $44.94 1 / 8 In. MINI JACKS 7 0 1 -1 0 0 ...... 100 pf p o ly s ty re n e ...... 25 903- 351...Mono with n/closed contact...32 7 0 1 -1 8 0 ...... 180 pf p o ly s ty re n e ...... 25 THE “ CLARIFIER" GUITAR 701 -1 0 0 0 ...... 1000 pf polystyrene ...... 25 EQ/PREAMP 903-353...Mono end. (open back)...... 26 7 0 1 -2 2 0 0 ...... 2200 pf polystyrene ...... 25 The “CLARIFIER” is an onboard preamp/EQ 903-355...Mono enclosed with contact...... 35 7 0 1 -2 2 0 0 ...... 3300 pf polystyrene ...... 25 module for guitar. This design, by Craig Anderton, RCA JAC K S 701 - 3 9 0 0 . 3900 pf polystyrene ...... 25 was first seen in the pages of GUITAR PLAYER magazine. Here’s what the CLARIFIER will do: 921-100...RCA jack, chassis m ount...... 34 702 - 0 0 5 ...005 uf mylar...... 12 Replace the guitar’s standard passive tone control 921-200...RCA jack on phenolic mount... .25 with a two control, active circuit which provides over 7 0 2 -0 1 ...... 01 uf m y la r...... 12 921-300...Dual RCA on phenolic mount... .43 7 0 2 -0 5 ...... 05 uf mylar...... 16 12 db of bass and treble boost and up to 6 db cut. .. Buffer your pickups from external loading, giving 1 /4 In. PHONE PLUGS 7 0 2 -1 ...... 1 uf m y la r...... 21 additional output and improve high freq response. .. 9 1 1 -2 0 1 ...M ono, black phone p lu g ...... 48 70 2 -2 2 ...... 22 uf mylar...... 33 Add a nominal 6 db of gain to give your signal a bit 9 1 1 -2 0 3 ...M ono, red phone p lu g ...... 48 7 0 3 -1 .0 ...... 1.0 uf tantalum .39 more punch, as well as improve the signal/noise ratio in multiple effects systems... make your guitar 911-205...Mono, chrome (metal) plug... .1.20 7 0 3 -3 .3 ...... 3.3 uf tantalum .49 immune to the high freq loss caused by long cable 911-211...Stereo, black phone plug ...... 65 runs. 1 /8 In. MINI PLUGS 7 0 4 -2 .2 ...... 2.2 uf e le c tro ly tic ...... 21 The CLARIFIER kit is available in two options, both of which include a high quality drilled, legended, and 7 0 4 -4 .7 ...... 4.7 uf e le c tro ly tic ...... 21 913-251...Mono, black mini plug ...... 38 masked circuit board, as well as complete step by 7 0 4 -1 0 ...... 10 uf e le c tro ly tic ...... 21 913-253...Mono, red mini plug ...... 38 step instructions. Kit 2450 contains everything 704-100...... 100 uf e le c tro ly tic ...... 31 needed for a complete unit.. Kit 2455 contains 913-255...Mono, chrome (metal) plug ...... 56 everything execpt the pots (for those who prefer a 7 0 5 -1 0 ...... 10 pf ce ra m ic d is k ...... 15 SWITCHING JACKS particluar brand of potentiometer). Batteries are not 7 0 5 -.0 1 ...... 01 uf ce ra m ic d is k ...... 12 included with either kit. These are stereo phone jacks that contain an u 7 0 5 -.1 ...... 1 uf ceram ic d is k ...... 17 KIT 2450....Complete CLARIFIER k it. $18.95 independent switching sywtem that is controlled by the insertion of the plug. Jack 905-301 contains the KIT 2 4 5 5 ..... CLARIFIER less controls ..$14.95 IC SO CKETS (soldertail) equivalent of a DPST normally on switch. Jack IC -S -0 8 ...... 8 pin high quality socket...... 27 905-302 contains the equivent of a DPDT on/on TERMS: (Check, Money Order, Cashiers Check - IC -S -1 4 ...... 14 pin high quality socket... .30 switch making it ideal for switching bi-polar power Add .75 if under $10.00)— ($10.00 minimum on IC -S -1 6 ...... 16 pin high quality socket... .34 supplies on and off in effects boxes, etc. C.O.D. (UPS only) add $1.50)— (Mastercard and IC -S -1 8 ...... 18 pin high quality socket... .40 905-301...Stereo jack with SPST switch.. .90 Visa: $10.00 minimum. You must supply exp. IC -S -2 8 ...... 28 pin hgih quality socket... .60 date.)— (Indiana residents add sales tax.) 905-302...Stereo jack with DPDT sw ...... 1.00 IC -C -0 8 ...... 8 pin economy socket...... 13 SHIPPING AND HANDLING: $1.00 plus 5% of IC -C -1 4 ...... 14 pin economy socket...... 15 purchase. We will credit any amount over our PGS ELECTRONICS IC -C -1 6 ...... 16 pin economy socket...... 17 standard rate. Route 25 - Box 304 IC -C -1 8 ...... 18 pin economy socket...... 20 SA TISFACTION GUARANTEED! IC -C -2 8 ...... 28 pin economy socket...... 40 Terre Haute, IN 47802 PROGRAMMABLE PRESET LEAD SYNTHESIZER

We had a lot of ambitious goals in mind when we use optional footswitches to control preset func­ began designing the Proteus I synthesizer. tions. Or respond tomorrow to needs that you can’t We wanted, first of all, to provide a quality piece of even imagine today. equipment that would offer wide range precision and We wanted Proteus to have a computer port that quiet, pure performance. So we designed Proteus would set the standard for versatility and ease of around the world recognized Curtis Electromusic use. While the interfacing provisions of some syn­ Chip Set to realize Oscillators and Filter with 12 oc­ thesizers are “tacked on” , forcing you to choose bet­ tave range, transient generator segments out to 30 ween keyboard or computer control (but not both) seconds long, exceptionally low noise and clean and forget about front panel controls completely. sound. Qualities you need for serious production The Proteus interface doesn’t put the computer bet­ work. ween you and your music. It puts the computer We wanted it to be easy to use on stage or in the where it belongs, at your side to help when you want studio. A keyboard that would let you get just the it to store or retrieve presets or keyboard sequences sound you wanted RIGHT NOW, without a lot of and completely out of the way when you don’t want knob twiddling and switch throwing. So we gave Pro­ it. There aren’t even any switches to throw, to use teus 16 presets and simple controls that let you the computer, just plug it in. quickly and easily step from one preset to another or We wanted to design a piece of equipment that instantly switch between presets. despite its high-tech complexity would be easy to We knew you wouldn’t want you to be locked into assemble and service, so we broke assembly down factory canned presets so we added an easy pro­ into small easily digested chunks with simple tests gramming facility that let’s you play with the sound along the way that lets you monitor your progress and develope just the tone color, texture and feeling and go from step to step with complete confidence. that you’re after before saving the setting of every To get the full details on the power and versatility of knob and switch with the push of a single button. PROTEUS, send for your PROTEUS Using/Assembly And Proteus’s internal memory keep-alive battery Manual today and you’ll also receive Craig Anderton’s means that the preset will still be there even after 20 minute demonstration cassette, (the cassette alone months of power-down storage. is worth the price) $10 refundable on kit purchase. We knew that any normalization plan, no matter how clever and well planned, must in subtle ways ORDER TOLL FREE WITH VISA OR MASTERCARD define and restrict the kinds of sounds that a syn­ thesizer can make. So after spending months 1- 8 0 0 - 654-8657 developing and refining an exceptionally versatile normalization plan, we added the most liberal collec­ 1-8750 PROTEUS MANUAL...... $10 postpaid tion of patch over hardwire points that you’ll find on 8750 PROTEUS I KIT was $ 2 ^ now $399 (26lbs.l any synthesizer. The patch bay lets you integrate ex­ Direct mail orders & inquiries to: ternal processing elements into Proteus’s signal path. Or interface to a wide variety of analog con­ m iA Electronics, Inc. trollers like sequencers and function generators. Or 1020 W. Wilshire , Oklahoma City, OK 73116 - (405)843-9626