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Designing 'Circuit-Bent' Instruments

REED GHAZALA: Designing 'Circuit-Bent' Instruments

In these days of sampling, DSP and physical modelling, you might think that building your own electronic instruments would be a daunting prospect. According to Reed Ghazala, however, it's a piece of cake — you don't even need to know how they work.

Sound On Sound's August 1999 feature on Damon Albarn's London studio attracted quite a few responses for its mention of "a mad guy in America" who had built a bizarre musical instrument from a Texas Instruments Speak & Spell toy. Among those responses was an email from the "mad guy" himself — whose name, it transpires, is Reed Ghazala. It also transpires that the Speak & Spell‑based device, designated by its creator the Trigon Incantor, is no one‑off but just one result of a well‑developed, and highly unusual, philosophy of instrument design. Unlike most instrument designers, moreover, Ghazala is only too happy to tell the world the secrets of his 'anti‑theoretical' technique. Over the last 30 years, he has created hundreds of unique instruments by applying the principles of what he calls 'circuit‑bending' — a process which, he insists, is straightforward, cheap, and open to anyone who can use a soldering iron.

"Circuit‑bending is the electronic art of the implementation of the creative audio short‑circuit," explains Ghazala. The process is beautiful in its simplicity: "In a nutshell, a battery‑powered, low‑voltage audio device (such as a toy or game) is opened to expose the circuitry. Using a wire, and while the device is making its original sounds, arbitrary short‑circuits are enacted upon the live circuit [ie. the wire is connected between randomly chosen points on the circuit board]. The results can be amazing, especially after cleaning, sharpening and expanding these eccentric voices with studio standards such as EQ and cautious reverb. Big, thick voices result — you'd never know you were listening to a 'toy'! These short‑circuits are then hard‑wired into the circuit through switches mounted on the unit's case. Circuit‑bending can get much deeper, but that's where it starts — it's a technique of chance, and no theoretical knowledge of electronics is needed whatsoever. It is, without a doubt, the easiest electronic audio design process in existence."

Starting Points

Ghazala's first 'circuit‑bent' instrument was created in 1967, as a result of an accident: "I had left a toy 9‑Volt transistor amplifier amidst the clutter of my desk drawer, with the back of its housing missing and the power turned on. When I closed the drawer, to my amazement, there suddenly came from within my desk miniature versions of the sounds I associated with the massive synthesizers of the day. While they're everywhere now, sound synthesizers at that time were still quite a mystery to most folks, and weren't that easy to come by. When I realised that the sounds I heard were the result of the toy amplifier's electronics accidentally shorting out against something metallic it was resting on, two ideas immediately struck: if these sounds are being created by accident, what could be done by purpose? And if this can be done to an amplifier, meant to amplify a sound but to make no sound itself, what would happen to sound‑making electronics when purposely shorted out in the same way?"

Financial constraints, the potential for inadvertently destroying equipment and — above all — safety considerations led Ghazala to experiment not with 'professional' gear, but cheap instruments and sound‑producing toys. "Frying a toy is much less upsetting than sizzling the oscillators in your vintage Moog," he acknowledges, adding: "Toys use relatively low operating voltages, usually 3 to 9 Volts, and are therefore unlikely to give you a jolt." He gives dire warnings about the dangers of attempting to circuit‑bend any instrument that runs from the mains, even via an AC adaptor; though he says that component failure as a result of circuit‑bending is rare, he also recommends that 'circuit‑benders' wear eye protection.

Chance: A Fine Thing

Even where Reed Ghazala designs instruments 'from the ground up', as with the Photon Clarinet shown, he puts them through the circuit‑bending procedure to discover new sounds and playing techniques.Even where Reed Ghazala designs instruments 'from the ground up', as with the Photon Clarinet shown, he puts them through the circuit‑bending procedure to discover new sounds and playing techniques.

What distinguishes circuit‑bending from conventional instrument design is the fundamental role played by chance. No attempt is made to discover how the toy or instrument being bent is 'supposed' to work; even those instruments which Ghazala designs from the ground up, such as his Vox Insecta and Photon Clarinet, are not spared: "After the theory‑true design drawings and after successful breadboarding and operation, I then circuit‑bent the Vox Insecta and Photon Clarinet also, blindly shorting them out everywhere to see what happened. With both of these instruments the circuit was then altered due to various circuit‑bending discoveries, which are now integrated into the final designs."

The Oddmusic web site at, which has a large area devoted to Ghazala and circuit‑bending, includes detailed instructions for modifying Casio's SK1 budget 8‑bit sampler. However, mass production of most circuit‑bent instruments would be almost impossible, as the results are so unpredictable: "It's very difficult to publish safe schematics; the original designs from the manufacturers changed often over differing production runs, so same‑named units may not 'bend' the same — even to the point where my charts can fry other people's models. However, I do publish or distribute everything else possible where I can."

Instructions for turning Casio's SK1 budget sampler into an 'escapist sample shuttle' can be found online.Instructions for turning Casio's SK1 budget sampler into an 'escapist sample shuttle' can be found online.

Developing Worlds

Given that electronic music was in its infancy in 1967, and has since developed enormously, one might wonder whether the same techniques that apply to the modification of toys and instruments from that era are still applicable today — but a part of the beauty of circuit‑bending, Ghazala insists, is that its methods and philosophy are largely independent of changes in instrument design. "Due to the very standard process of circuit‑bending, the changing technology of target circuits alters things very little as far as the actual approach goes," he explains. "An occasional drawback I run into might be the 'epoxy dot'‑style ICs found now and then, offering little for the experimenter to explore. But this event is far outweighed by the other electronic advancements resulting in more and more complex circuits appearing at lower and lower prices in the second‑hand marketplace."

Developments in electronic technology have, however, opened up a greater range of possibilities for the circuit‑bender in terms of designing new control interfaces: "The changes to my approach over the years have centered around advancing the technical infrastructure of the added electronics. Various body contact materials, for conducting electricity through the player for sound modulation, have been discovered. Lighting devices within instruments have evolved from tungsten to LEDs to ultra‑miniature backlight tubes to lasers to cold light strips pulsing with the sounds. I'm about to undertake an instrument design containing a plasma display too. Also, miniaturization of available design components now allows me to place sensors (humidity, solar cells, photo resistors, and so on) where I certainly couldn't have earlier."

Surface Noise

Just as Ghazala's circuit‑bent instruments are constructed by deliberately ignoring the way in which their original designers intended them to work, so too he constructs new user interfaces which ignore, and often obscure, the ways in which the original instruments were supposed to be played. Front‑panel legending is obliterated with spraypaint; new controls, often based on optical or touch‑sensitive components, are added in strange, quasi‑organic housings. "The personality of a circuit‑bent instrument, as all users discover, is very animal‑like," explains Ghazala. "The eccentricities of voice and behavior feel organic. In truth, the often unstable nature of bent circuits does more parallel the behaviour of creatures of choice than the prescribed behaviour dictated by the vast majority of electronic designs. At any rate, the personality of the electronics of circuit‑bending surely asks to be extended into the visual aspect of the instrument.

"Along with many complex surface‑finishing techniques — layers of reactive paints, fluorescent dusts, laser‑etched flake, tinted final glosses, and so on — I often embed eyes into the instruments, the case material bulged out as though the eye were a real growth. These might be actual blown‑glass prosthetic human eyes, backlit by pulsating multi‑colored LEDs and serving as envelope peak pilots, or they might be accurate glass animal eyes with light sensors behind them, to be covered by the hands for playing."

Rather than taming the inherent instability and unpredictability of his circuit‑bent creations, Ghazala's control surfaces often seem designed to emphasise these qualities. A key role for circuit‑bent instruments is in the production of 'aleatoric' (chance‑based) music, and for adding such elements to more traditional forms. The radical user interfaces help the player achieve this, both by diverting him or her from applying conventional instrument‑playing techniques, and by providing new ways of triggering and modifying the chance‑based sounds.

As an example, Ghazala explains the design of the Trigon Incantor, based on a heavily modified Touch & Tell toy, which is spray‑painted, adorned with switches, and — most remarkably — on which rest a number of enormous steel ball‑bearings: "The Trigon Incantor's playing stage requires pressure to trigger a sound sequence; a continuous sound requires continual pressure. This continuous pressure is needed when creating aleatoric music to keep things going. While a player can use a fingertip to initiate a sound, and use constant pressure to keep the sound going, the steel balls rolled about make this continuous pressure (and sound production) much easier. But they're round, and unless the Trigon Incantor is sitting perfectly level, a round steel ball won't stay in place on the original smooth stage. This suggested a textured surface; the stage material was researched. In turn, a new playing technique was established.

The Trigon Incantor, based on Texas Instruments' classic Speak & Spell toy.The Trigon Incantor, based on Texas Instruments' classic Speak & Spell toy.

"This instrument also looks to a single body contact for pitch‑bend: a tiny brass ball is simply touched with the fingertip to impart a nice vibrato in rhythm with the finger pressure — the way a violinist rocks a finger on the string. But the randomness of the Trigon's output is furthered by the eclipsing of the original graphics over the 36‑zone stage, extending the alien nature of the whole instrument and asking the musician to rely upon a sense of spontaneity within the musical scheme at hand. However, it's not hard to visualise the matrix of zones if repeatability is of the essence during other of the Trigon Incantor's operations.

"Standard Incantors, made from the now‑extinct Speak & Spell series, are more straightforward. With the exception of body contacts, pitch dial and hand‑shadow loop incrementing, the instrument is still primarily actuated as usual by pressing the 'keys' of the membrane keyboard. Unlike the Trigon, the design of the membrane keyboard presented no problems and is still used with original graphics evident. True, waving a hand over the instrument to step through different loops is an odd user interface, and is a much finer loop‑control system than the alternate push‑button switch, also installed in the bending process.

Ghazala's Video Octavox atop a television set.Ghazala's Video Octavox atop a television set."On the topic of unusual player interfaces, my Video Octavox serves as a pretty good example. It's a multi‑channel instrument that is attached to a video screen for activation. Each channel consists of a string oscillator (violin, viola or cello) whose pitch is governed by a light sensor. The sensors suction‑cup to the screen, and any video programme results in an other‑worldly string ensemble performance. A Photon Clarinet is also built in as a lead voice to play amidst the drifting chord clusters of the string section. As you've guessed, a video tape suddenly becomes a programme medium here, like the perforated paper rolls of a player piano. It gets stranger...

"Imagine a video camera is aimed at a well‑lit stage upon which dancers stand, draped in black before a black curtain. Each person, standing on their mark, holds a reflective shield. The monitor screen, with the Video Octavox sensors attached, transforms the dancer's shield movements into music — the dancers know which voice is theirs and where to hold (and angle) the shields so as to control the voice's pitch (via their shield appearing upon the monitor under one of the instrument's light sensors). To the greater confusion of all, dance choreography as well as stage lighting effects are now the controlling agents in playing this instrument. So, yes, the player interface can get pretty extreme with such an unusual instrument."

Making Music

Circuit‑bent instruments, then, are unpredictable, unstable, often show no regard for standard Western scales, and can demand wholly novel playing techniques. You might therefore be forgiven for wondering exactly what sort of music can be made using circuit‑bent instruments, or would benefit from their addition. According to Ghazala, their applications are surprisingly varied: "Circuit‑bending is creating its own style of music, and this will be its strength, its identifier as time passes and compositions are recognised. As to fitting into present musical styles, not too long ago I would have been reluctant to suggest these instruments might be accepted anywhere outside of deep experimental circles. But musicians are using them in all kinds of compositions, from rock tracks to jazz improvisation to rap and hip‑hop to, believe it or not, acoustic slide guitar Delta blues. And, of course, all kinds of experimental work everywhere.

"I see circuit‑bending's offering to the world of music as a new voice‑system to be added to the old list, a separate subcategory of electronic, since it embraces its own specialised techniques, voices and aesthetic, and since the art is exploding internationally and can't be ignored. To my mind it accompanies rather than challenges things musically. Perhaps I should mention that I have several hundred traditional electronic and acoustic world instruments at hand in my collection; I admire these very much. And the vast majority of music albums in the collection are more traditional than experimental.

"But, not surprisingly, circuit‑bending's voices along with the layers of aesthetic anti‑theory and 'clear illogic' techniques attract many persons who are tired of the musical fodder of popular sub‑culture as well as that of the mainstream, and who want to make a strong musical statement in response. Until the saucer lands in your backyard, circuit‑bent instruments are about as close as you can come to getting your hands on truly alien music engines today."

Thanks to John Pascuzzi for permission to quote from the Oddmusic web site.

Circuit‑Bending In More Detail...

Found a cheap audio toy or instrument, and fancy trying your hand at circuit‑bending? Here are some tips on what to do and how to do it from Reed Ghazala's more detailed guide, available in its fullest form from the Oddmusic web site at The tools of the trade are simple and inexpensive: a small soldering iron, a set of small, non‑insulated screwdrivers, alligator clips, some leads, a selection of cheap electrical components which can form the controls of your new instrument, and a drill to mount them in its case. Again, it should be emphasised that the techique is suitable only for battery‑powered instruments.

"First, clip the smallest two screwdrivers in the alligator clips at the ends of a lead to give you a wire with a probe at each end. This is your most important circuit‑bending tool. (Obviously, a custom test lead with a permanent probe at each end can be made for this job). Remove the back from the game or toy to expose the circuitry. Turn the device on and activate the sounds (press keys/buttons, or tape/wedge them in place to sustain sound production).

"With the device making a noise, press the tip of one of the test lead's screwdrivers to a printed circuit trace, component lead or integrated circuit pin. Keep this screwdriver tip in place for the next step. Now, with the other screwdriver at the opposite end of the test lead, begin touching various parts of the circuitry while listening for interesting changes in sound. Electricity will follow the new course you've provided with the lead. This may have no effect on the sound at all. On the other hand, the audio effect may be outrageous. Each time an interesting sound is created, note with a marker directly on the circuit board the pair of points that were connected to each other to create the sound.

"Once the travelling end of the test lead has explored the circuit's corners and all interesting connections have been noted, place the stationary screwdriver tip on a new circuit point. Again, the travelling end of the test lead explores the rest of the circuit; interesting sound‑changing connections are marked. This process is repeated until the entire circuit has been searched in such a manner. Given a bit of luck, the circuit will soon be marked with a number of potential connections discovered with the test lead.

"At this point, various choices face the explorer in implementing the creative short‑circuits discovered:

  • Direct Wiring

"Wires can be soldered directly between the points marked as pairs on the circuit board. In the middle of these wires would be soldered toggle switches so that these new sound‑activating connections can be turned on and off at will. The wiring procedure begins with counting how many pairs of connections you'll need switches for. Next, decide how the switches will be mounted on the device's case (remember to check for internal clearances so that the backs of the new switches don't hit the device's internal parts when the unit is reassembled). Holes are drilled, the switches are mounted, the pairs of circuit‑bending connections are then soldered through their respective switches and the device is reassembled.

  • Potentiometers

"Instead of switches, potentiometers (variable resistors) can be soldered in the middle of the pairs of connections. In many cases this will allow the adjusting of the new effect with the turn of a dial. Switches can be used along with potentiometers between the pair of circuit‑bending connections as well. In this way, effects can be preset with the potentiometer's knob and turned on and off with the switch. A wire would be soldered to one of the points in a circuit‑bending pair, through the toggle switch, then through the potentiometer and back into the circuit‑board to the other point of the pair. This switched‑component wiring may be used with any components, including the following:

  • Capacitors

"Capacitors, again available in a wide range of values, can be wired between the pairs of points. These may change the tone of the effect produced or pulse the sound in differing ways.

  • Photo Resistors

"These are light‑sensitive potentiometers (sometimes called 'cadmium sulphide cells'): instead of turning a dial to vary the resistance and thereby the sound, hand shadows are allowed to fall upon the photo‑resistors.

  • Solar Cells

"These are light‑sensitive wafers that convert light into electrical energy. They can be used to inject their small voltage (or resistance in some situations) into the circuit between the paired bending points and thereby change the sound.

  • LEDs

"Light‑emitting diodes are usually, for the sake of circuit‑bending, used to provide low‑voltage light sources. You may find points on the circuit you're bending between which LEDs will glow or pulse. These can serve as function indicators or pilot lights. An LED wired to the speaker leads may work as an envelope light also, flashing with the intensity of the sound waves.

  • Humidity Sensors

"These are sensors that convert airborne moisture into electrical resistance. This can give a breath‑control function to an instrument — changing pitch, perhaps, as the sensor is blown upon.

"There are many other components that can be wired into the path of the pairs of circuit‑bending points, but the above will launch hundreds of possibilities as well as pave the way towards the understanding of wider concepts."