The SK1 Aleatron, based on the well-known Casio sampler, is one of the most outstanding examples of the circuit-bent alien music engine to exist. Its output is nothing short of stunning.

Excerpted from Reed's EMI article on the instrument:

Readers of this article series have inquired over the years about the viability of keyboard instruments as a focus for circuit-bending. While I'm inclined to think the end result of the bending process is often better suited to less linear sound machines, keyboards were an early target of mine, and the circuit-bent SK-1 is an exceptional example of deep-end anti-theory application combined with equal-tempered polyphony. Abstract sound fields thick and intriguing, complex voices, split keyboards, strange tone shaping and extended ADSR envelopes begin the list of new possibilities...

Following the usual process of circuit-bending, the instrument was expanded upon to the degree of now providing 28 new controls (switches, dials and body-contacts).

Once again, the creative short-circuit is on the loose, the repercussions of its catalytic anti-theory wreaking indeterminate digital havoc within the all-too-proper halls of previously strict program logic.

My SK-1 circuit-bending applications fell into (the following) sections. These are the IMAGE GROUP of 9 switches, the SKEW GROUP of 7 switches + 1 pot, the BODY CONTACT GROUP of 3 brass spheres, the PITCH control dial, the POLY control dial, the AXIS GROUP of 3 switches, the RESET GROUP of 2 switches, and, lastly, the SOUND ENVELOPE LED.


Turning these switches on singly or in combination will create up to 8-step sound envelopes, up to five keyboard split points (different sounds assigned to various key groups), oddly evolving tone clusters and extended decays lasting up to 30 seconds or more. The multi-step sound envelopes may combine voices from the SK-1's menu or create new voices, changing voices, strung end-to-end and finally settling upon an unusual sustained tone, or slowly fading away. Additionally, choosing a different voice from the menu may completely change the effect of a given IMAGE switch.


The intensity of the effect (of these seven switches) is governed with the SKEW pot, and the musician controls the duration of the effect with the two miniature actuation switches (one for momentary, one for hold). The SKEW effects are similar to the IMAGE effects with the addition of adding pulsings to final voice segments of multi-step sound envelopes. Assorted sustains, echoes, repeats, doublings, choruses and harmonic distortions also arise from the SKEW effect group.


Primarily pitch controls, bridging with a fingertip the gap between the center sphere and the one to its left will lower the frequency. Bridging the gap between center and right will raise the frequency. Actually, just touching either outside sphere will bend the frequency, but not as dramatically as when bridging the gaps as mentioned. Very nice real-time vibrato and pitch-bend are possible in this way. Beyond this application, a moistened fingertip pressed across all three contacts will bring on an assortment of deep-end audio calisthenics simply impossible to describe!


(adjusts) the overall pitch of the instrument.


This control is used to adjust the degree of polyphony, especially valuable when applied to the dense abstract sound fields generated through other circuit-bending controls.


Drastic voice changing in the form of distant ethereal sounds, rich tonal swells, seemingly chance music cycles, metallic percussive bursts and endless de-tuned sustains are a few of the effects created by the AXIS GROUP.


These two switches represent a choice of “HARD RESET” or “SOFT RESET”. As I've stated before, the unusual anti-theory design system of circuit-bending can create digital exasperation in logic routines, otherwise known as program crash. When the circuit-bent SK-1 crashes (and it will), four reset options are available. Casio's front panel “RESET” button might work. If not, turning the SK-1's main power switch off and back on might work. If both of these fail, my “SOFT RESET” miniature push-button on the left side of the case could solve the problem. The “HARD RESET” is a “push-on/push-off” switch situated next to the mini switch just mentioned. This is the deep crash remedy since it completely breaks the circuit between the power supply and the board. Therefore, it is also a MASTER POWER switch. This is the standard reset I include on many circuit-bent instruments prone to crash. Can you keep a secret? It does the same thing as the tiny reset switch you're instructed to push with a pencil tip in case of malfunction of your calculator, answering machine, musical keyboard and lots of other digital whatevers. Yep, the Big Guys' theory-true toys crash deep enough all by themselves to need as drastic a thing as battery disconnection to set them straight again too!


This clear, bright, red LED (2,000 mcd) fluctuates with the intensity of the sound.

Exploring the SK-1 circuit is fascinating. In the EFFECT GROUP discussions above I've only begun to describe the major effects available within the separate groupings. Not only can each group be depended upon to produce many more effects than those covered, when multi-group combinations are experimented with (e.g. IMAGE switches 1,3,7 + SKEW switches 2,3 + AXIS switch 1 while touching body-contacts or sweeping POLY dial), the surprising nature of circuit-bending's ability to always generate new audio behavior becomes evident. My initial examination of such switching combinations produced 30 strong variations using the PIANO voice alone.

On some deep-end settings the circuit-bent SK-1 becomes an aleatoric music box, evoking outlandish chance compositions. Other settings turn the keyboard into an alien sound field generator, inter combining curtains of relatively pitch-free noises. Peculiar mixtures of countless types emerge as one moves deeper into switching possibilities... and I now find myself in the position again of trying to describe the eccentric, many-nuanced voices of circuit-bending. Like trying to define a rare flavor or shifting color.


This instrument is a sonic treasure chest of mysterious pathways and literally endless soundforms to discover. Undoubtedly one of the most intriguing keyboard instruments on the planet. Price for the SK1 Aleatron Special Edition is $3,500 plus shipping.



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