Circuit bent keyboard. THE CASIO SK-1


Escapist Sample Shuttle

by Q. R. Ghazala

The glass within my workshop window is 70 years of age. Its thickness varies, and also the world outdoors goes by in fluid, undulating waves. Within the cracks of the glass, in which a forgotten autumn’s chore might have left its mark, is visible all of the colors from the rainbow, refracted splendidly for anybody provided to close inspection. Glued to some rippled pane, an excellent rubber skink watches a little cricket ascend the yellowed fringe of a classic skyharp postcard. With the Victorian very teardrops and hanging stained glass spheres, with the pinned-up templates and photos and chipped eco-friendly paint from the window’s dusty sash flows the orange evening sunlight, wavy after passing with the magic window-lens. Very simple comes now and lightly swings the antique glass balls, their forecasted optical flares rocking backwards and forwards upon circuit sketches, colored-light fairies on the rippled orange ocean.

The plans, today, where the fairies dance are individuals from the circuit-bent Casio SK-1. (“Circuit-bending” refers back to the procedure for creative short-circuiting through which standard audio electronics are significantly modified to create unique experimental instruments. An additional description of those techniques could be read in EMI Volume VIII #1, 1992.) Readers want to know , series have asked through the years concerning the viability of keyboard instruments like a focus for circuit-bending. While I am inclined to consider the finish consequence of the bending process is frequently more appropriate to less straight line seem machines, keyboards were an earlier target of mine, and also the circuit-bent SK-1 is definitely an exceptional illustration of deep-finish anti-theory application coupled with equal-tempered polyphony. Abstract seem fields thick and intriguing, complex voices, split keyboards, strange tone shaping and extended ADSR envelopes begin their email list of recent options. but more about may be in just a minute.

Casio’s SK-1 introduced digital sampling to more individuals than every other sampler up to now. The SK-1 started to look on store shelves in 1986. Because of its time, at its cost with its functions, there is little else enjoy it. Primary options that come with this 32-note mid-size keyboard include:

4-note polyphony, available live and in memory for digital record/playback functions of two sorts: 1) real-time 4-note polyphony, and a pair of) 3-funnel multi-track memory along with a “one key play” system allowing notes in memory to become by hand sequenced for editing purposes

5 PCM voices, 1 user-sampled voice, 3 harmonic synthesis voices and something user-adjustable harmonic synthesis voice (this nice feature supplies a tone by which the majority of the first 16 harmonics can be found and could be adjusted in strength, with as many as 14 amounts of accentuation for every)*

13 different preset ADSR envelopes which may be put on any voice being used-

Preset portamento and vibrato effects

8 bit PCM sampling at 9.38 kHz (sample time is roughly 1.4 seconds)

Built-in condenser microphone for inputting samples, in addition to two input jacks — line and exterior microphone

11 auto rhythms with chord accompaniment

. and finally, that button everybody dreads hitting accidentally. the Demo Tune (which circuit-bending reconstructs inside a wonderfully irresponsible manner).

*PCM (Pulse Code Modulation) is really a high-quality way of digital audio information systems. ASDR (Attack-Decay-Sustain-Release) describes the 4 primary parameters of seem envelope transients as generally addressed in electronic synthesis techniques.

No, it isn’t a hi-fi sampler. But lots of people found the SK-1’s audio quality sufficiently good to keep interest on high for a while.

Lots of SK-1s continue to be around today, with patience waiting to become reborn through circuit-bending. Because the resultant instrument is really exotic in the behavior, so intriguing in the sounds and thus attainable through standard rewiring techniques, I’ll devote this column towards the SK-1’s anti-theory transformation.

My first SK-1 was bought during its heyday in a cost close to $90. I rapidly made two modifications and, until recently, thought no further about altering it. These early changes led to two jacks being installed on the SK-1’s situation. One was wired in order that it would pay a remote sampling trigger to make use of along with an exterior microphone. Another jack was wired to simply accept programmed current pulses (for example individuals generated by drum machines) in order to trigger the “one key play” function therefore turning the SK-1’s note memory right into a nicely controlled sequencer. Push “start” around the drum machine and both it and also the SK-1 perform in tight synch. Fun.

Years pass. the SK-1 is overshadowed by industry changes and pressed to the rear of the shelf (go remove individuals batteries!). Couple of things have a tendency to encourage a circuit-bending experiment greater than locating a promising target device in a bargain cost. Particularly if the system is a replica of the item you already own and take care of, and it is one you want to bend but they are reluctant for anxiety about damaging it along the way. And So I was happy to lately look for a SK-1 (having a key missing) for just $1.50 in a thrift shop. Oddly, a few days later I discovered another SK-1, this time around fit and costing $5.00 in a different second-hands shop. The main one using the missing key grew to become my prototype, the $5.00 unit grew to become the finished instrument and my original SK-1 continues to be it had been before.

Following a usual procedure for circuit-bending, the instrument was expanded upon as far as of now supplying 28 new controls (switches, dials and the body-contacts), 7 micro eco-friendly & red Brought logic pilots as well as an ultra-vibrant seem envelope Brought. 36 modifications. With the added controls switched off, the SK-1 operates normally. The adjustments are simple to find and therefore are available to anybody familiar by using a soldering pencil (small, low-wattage soldering iron).

Once more, the creative short-circuit is around the loose, the repercussions of their catalytic anti-theory wreaking indeterminate digital havoc inside the all-too-proper halls of formerly strict program logic. The brand new controls were found 1 of 2 ways. Either by hearing the instrument’s voices while 1) utilizing a wire to momentarily connect arbitrary circuit board suggests one another (this giving rise to twenty from the 22 circuit-bending switches, their intention being to apply and mix the creative short-circuits just discovered), or 2) using fingertips for connecting arbitrary circuit suggests one another (the three body-contacts and a pair of from the 3 dials [potentiometers or containers, variable resistors] put together in a way).

This last activity, touching an energetic circuit-board using the fingers to listen to what changes exist in the seem, ought to be done just with low-current, battery-powered circuitry. Circuits that contains large capacitors or step-up transformers should be prevented. These are really simple to recognize search for a beginner’s electronic Project book if unfamiliar. These elements usually come in various lighting circuits, practically never within the audio electronics suitable for circuit-bending. Anyway, the concept is the fact that interesting sounds as a result of finger contact can be difficult-wired into existence by soldering a pot (variable resistor) backward and forward points so discovered. The center solder lug from the pot is wired to 1 circuit point, an outdoors lug from the pot to another circuit point. In the end, that is what bodies are doing within the same situation. Because the electrical power is carried out using your flesh its potential changes while you vary the resistance presented it by modifying pressure of the fingertips around the circuit-board. You’ve become, essentially, a flexible human resistor (aren’t all of us?). Conductivity will vary from person to person, so there’s no exact recommendation I’m able to give regarding the resistance rating from the pot. Experiments having a 500K will give you a great beginning point.

My SK-1 circuit-bending applications fell into 9 sections. Fundamental essentials IMAGE Number of 9 switches, the SKEW Number of 7 switches + 1 pot, your body CONTACT Number of 3 brass spheres, the PITCH control dial, the POLY control dial, the AXIS Number of 3 switches, the RESET Number of 2 switches, the LOGIC PILOTS Number of 7 LEDs + on/off switch and, lastly, the Seem ENVELOPE Brought. None of those expansions from the SK-1 were difficult to find. Following are brief explanations of those new circuit-bending breakthroughs, in addition to guidelines for applying the alterations yourself.

Circuit bent keyboard. THE CASIO SK-1 backwards and

1) Although it appears I’ve not injured any normal functions of my 3 SK-1s, there is no be certain that an association I did not try exists that may damage or destroy the circuit. Different color leaves, manufacturer’s design changes can produce a situation where a formerly reliable circuit-bending connection becomes either inoperative or destructive on the later model. Therefore, while my instructions are valid in relating to my SK-1s, they are certainly not advisable for yours.

2) The bending procedure requires a lot of soldering small wires to very carefully spaced IC pins protruding with the bottom from the board. Careful connections are necessary to prevent creating solder bridges between your pins. Quick connections will also be advisable so they won’t overheat the interior IC electronics attached to the pin. I personally use a 30-watt grounded soldering station with lengthy, tapered, 1/16″ wide chisel-tip around the soldering pencil. For point-to-point connections I personally use insulated bought-in-quantity 30-gauge “wire-wrap” wire, the wilder color the greater, and lead-free silver electronic solder.


For persons thinking about experimenting by themselves SK-1s, my descriptions below assume the significant orientation of circuit is really the bottom from the board faces the experimenter which the parallel grouping of three large (28 pin) ICs would be to the underside left (on reverse of board). Within this position a medium-sized electrolytic capacitor can be found at the very top right corner from the circuit-board. This must be relocated elsewhere inside the situation (on insulated wire extensions) to spread out up room behind it for brand new controls to become mounted.

Image Group
These 9 switches right from the keyboard are interconnected between various pins around the farthest left from the three ICs pointed out earlier. Experiment to locate these connections yet others. Turning these switches on singly or perhaps in combination can create as much as 8-step seem envelopes, as much as five keyboard split points (different sounds allotted to various key groups), oddly evolving tone clusters and extended decays lasting as much as thirty seconds or even more. The multi-step seem envelopes may combine voices in the SK-1’s menu or create new voices, altering voices, put up finish-to-finish and lastly settling upon a unique sustained tone, or gradually disappearing. Furthermore, selecting another voice in the menu may completely change the consequence of given IMAGE switch.

Skew Group
These seven switches and 10K pot make connections between various pins of the identical large IC along with a common point at the base right-hands side from the board, that being to some pin around the 14-pin nick just left of the board mounting screw. Again, experiment. Basically, the 5 primary SKEW switches connect five pins from the large IC towards the smaller sized IC by running through among the other two smaller sized switches within the group. This signal also goes through the 10K pot. The pot adjusts the effectiveness of the signal passing backward and forward chips, and also the smaller sized push-button and toggle switches allow the option of either intermittent or continual utilisation of the selected SKEW effect while playing. Therefore if, say, SKEW switch 1 is switched on, an association is created from a pin around the large IC and also the pin around the smaller sized one. The concentration of the result is governed using the SKEW pot, and also the music performer controls the time period of the result using the two miniature actuation switches. The SKEW effects are the same IMAGE effects with the help of adding pulsings to final voice segments of multi-step seem envelopes. Assorted sustains, echoes, repeats, doublings, choruses and harmonic distortions also arise in the SKEW effect group.

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Body Contact Group
These 3 brass balls are wired to 3 circuit traces just left from the master tuning trim pot soldered in place in the heart of the board. Mainly pitch controls, bridging having a finger the space between your center sphere and also the someone to its left will lower the regularity. Bridging the space between center and right will heighten the frequency. Really, just touching either outdoors sphere will bend the regularity, although not as dramatically as when bridging the gaps as pointed out. Excellent real-time vibrato and pitch-bend are possible in this manner. Beyond this application, a moistened finger pressed across the 3 contacts brings on a variety of deep-finish audio calisthenics simply impossible to explain! Tech Note: On the crowded circuit board it’s not easy to inform just which traces your fingers are touching to produce the audio changes heard in this procedure for exploration. Holding metallic jeweler’s screwdriver in every hands will help you to touch apparent and particular traces around the board. Electricity will flow into one screwdriver, using your body and the other screwdriver into the circuit. Different hands pressure around the screwdrivers will help you to take notice of the aftereffect of altering resistance backward and forward potential body-contact points.

Pitch Dial
This is just a 500K pot wired backward and forward outdoors body contacts. Reducing the resistance enhances the overall pitch from the instrument.

Poly Dial
Another 500K pot, that one is connected between your right-hands lug from the SK-1’s on-board master tuning trim pot and then any of numerous potential traces around the board. Try traces one inch approximately below center mounting screw. Once the resistance is decreased, an email or two polyphony will gradually diminish. This control can be used to regulate the quality of polyphony, especially valuable when put on the dense abstract seem fields generated through other circuit-bending controls.

Axis Group
These 3 switches connect a pin around the large left-hands 28-pin nick (again) to 3 pins around the two 28-pin chips to the right. Many options here. experiment! Drastic voice altering by means of distant ethereal sounds, wealthy tonal swells, apparently chance music cycles, metallic percussive bursts and endless de-tuned sustains really are a couple of from the effects produced through the AXIS GROUP.

Reset Group
Both of these switches represent a range of “HARD RESET” or “SOFT RESET”. As I have mentioned before, the bizarre anti-theory design system of circuit-bending can make digital exasperation in logic routines, also known as program crash. Once the circuit-bent SK-1 crashes (and it’ll), four reset choices are available. Casio’s front panel “RESET” button might work. Otherwise, turning the SK-1’s primary on / off switch off and back on might work. If these two fail, my “SOFT RESET” miniature push-button around the left side from the situation could solve the issue. This will make exactly the same connection as IMAGE switch 2. During initial prototyping I observed this connection could reset certain crashes without powering-lower the system. Yes, I possibly could just switch IMAGE switch 2 on and back away, however the small push-button is simpler, faster, and much more taken care of while playing. The “HARD RESET” is really a “push-on/push-off” switch situated near the small switch just pointed out. This is actually the deep crash remedy because it completely breaks the circuit between your power and also the board. Therefore, it’s also an expert On / off switch. This is actually the standard reset I include on the majority of circuit-bent instruments vulnerable to crash. Are you able to have a secret? It will exactly the same factor because the small reset switch you are expected to push having a pencil tip in situation of malfunction of the calculator, answering machine, musical keyboard and a lot of other digital whatevers. Yep, the large Guys’ theory-true toys crash deep enough simply by themselves to want as drastic a factor as battery disconnection to create them straight again too!

Logic Pilot Group
This number of seven miniature red or eco-friendly LEDs is implemented by connecting the anodes (+ leads) from the LEDs to numerous pins from the large right-hands 28-pin nick. All Brought cathodes (- leads) then connect via a LOGIC PILOTS on / off switch (on back of situation) towards the gloomy from the power. The change to turn them off is required for 2 reasons. First, if left on they still drain power unless of course my added master on / off switch (HARD RESET) is switched off. Second, certain IMAGE switches overdrive the LEDs when switched on, risking eventual burnout. These LEDs flash mysteriously as logic levels (voltages) go low or high because the instrument functions. These may also be considered STATUS LEDs, and could be quite informative when become accustomed to about this along with other circuit-bent instruments. I have drilled holes of these along the top SK-1’s situation having a couple of also mounted below, amongst the control buttons. Circuit connections of these are discovered exactly the same way as switch connections. Simply employ LEDs with alligator clip test lead extensions instead of the typical short-circuit exploration wire. Keep in mind that LEDs are polarized semiconductors: if the Brought will not light, try reversing its leads and reconnecting it towards the circuit. If the Brought glows too brightly or will get hot, try connecting a resistor (experiment around 100 ohm) between your LED’s anode and also the circuit.

Seem Envelop Brought
This obvious, vibrant, red Brought (2,000 mcd) is connected over the speaker terminals and fluctuates using the concentration of the seem without disturbing seem volume or clearness (which isn’t always the situation with this particular parallel wiring plan). LEDs may also be connected in series having a speaker if more energy is required to bring them. Seem envelope Brought connection points can be found by attaching one Brought result in a speaker terminal after which touching extra time from the other Brought result in parts from the active circuit. Actually, such envelope LEDs could be driven by points discovered around the board getting no direct link with the speaker whatsoever.

As noted before, circuit-bending the SK-1 does require a large amount of careful work since tolerances of both soldering and component placement are tight. A lot more can be done than I have done. Still, you may wish to add, say, merely a body-contact and then leave all of those other SK-1 untouched.

Any recently bent instrument presenting significant seem forms needs a visual transformation too. When the holes were drilled to simply accept the brand new switches, containers, LEDs and the body-contacts, I colored the situation of my circuit-bent SK-1 a hi-gloss fire engine red. Over that went a set black crackle coat. This is a kind of paint that contracts and cracks apart because it dries, departing a natural-searching and somewhat fractalized pattern. From far beyond the situation a sweep in mid-air of holographic micro glitter (several specks could easily fit in the us dot of the letter i) was rained lower to the housing, falling just like a star field over the scarlet veins within the black crackle field. These small particles reflect an excellent spectrum of sunshine, shifting hue in symphony as viewing angles change.

A higher-solids obvious gloss final coating ended up being applied. This deepens colors, works as a sealant and offers a surface where an additional-fine-tip opaque paint marker may be used to label the brand new controls, and re-label that old, their getting been colored in the refinishing process. New controls will be mounted, unit is reassembled and wiring is begun. Using the SK-1 I made the decision to not refinish either the situation bottom or even the strip over the keys which contains envelope symbols.

Be forewarned that if you choose to dismantle the whole device to refinish the situation as I have done, the laptop keyboard “trees” need special handling. All of the keys, in separate sets for white-colored and black, are linked to a typical tree and take away as single units. It’s the junction of key-to-tree that’s very fragile and should be handled with real care. It requires little pressure to bend a vital from alignment or snap them back completely.

Going through the SK-1 circuit is fascinating. Within the EFFECT GROUP discussions above I have only started to describe the main effects available inside the separate groupings. Although each group be depended upon to create a lot more effects than individuals covered, when multi-group combinations are attempted (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 capability to always generate new audio behavior becomes apparent. My primary study of such switching combinations created 30 strong variations while using PIANO voice alone.

On a-finish settings the circuit-bent SK-1 becomes an aleatoric music box, evoking outlandish chance compositions. Other settings turn the laptop keyboard into an alien seem field generator, intercombining curtains of relatively pitch-free noises. Peculiar mixtures of numerous types emerge as you moves much deeper into switching options. and that i now find myself able again of attempting to explain the eccentric, many-nuanced voices of circuit-bending. Like attempting to define an uncommon flavor or shifting color.

Because it frequently is by using circuit-bending, these more extreme settings impose a control/non-control balance which takes getting accustomed to. Program crash is frequently inevitable under these conditions. Charting patch settings and sequences goes a lengthy method to establish reliable interactions, however the temptation to visit one step further and find out ultimately ever present. I accept, even benefit from the non-control facets of circuit-bending, feeling they increase the mystery, and knowing that they’re a fundamental element of the entire fascinating procedure that I have grown to savor a lot. I am advised from the orange evening light through my wavy glass, and also the prismatic fairy-flares dancing along its crests upon my SK-1 plans when i sitting lower to start penning this article.

I’ll admit I figured as it were of activating the overhead drawing lamp, chasing the sunshine fairies away and so i could better see my notes. However, you know, I did not.

CASIO SK-1 “Modded Retro-SK” circuit bending

  • Steven Clements: LOL
  • RetroSound: 😉
  • syzygywell: haha I was thinking.. holy crap! there is no way a circuit mod sounds like that on this thing. (I mean I know you get great sounds out of your gear but this was ridiculous) and then I thought he’s got to be running something else through this.. but I don’t think it takes audio.. and then I saw the quotations (Ha.. well it’s late so I was a bit slow, but my ears weren’t)
  • Nik Neuy: i share your thoughts about circuit bending. There are only a few that make decent mods.. the others just circuitrape and playing garbage
  • rg7120: You could sample a Minimoog, but then it would be a lofi 8 bit Minimoog.
  • tannerin: Guys, they’re not rare. *Has one on the shelf next to him*
  • René Christensen: :O neat!
  • Kurt Woloch: So… it is not possible to have the keyboard sound like this by sampling this sound?
  • Chaise Rouge: hahaha this is a big big joke! fun…
  • wavebox2011: you can mod my pocket calculator to sound like a jupiter-8. i totally trust you. 🙂
    hehe, cool video!
  • robstoj69: dude u can use it as a synthsied bass cuz it sounds so bassy
  • Il Cuor di Leone: Which presets was used?
  • R.L. Bogdanović: and i thought finally someone made circuit bending sound more than just *hssss and *ftzzzzziiiaarks
  • Lachlant1984: The synth samples you used in this video and the piece of music you were playing remind me of Sexy Boy by Air, were you inspired by Air when you recorded this?
  • Bryan West: Nice one!!!!
  • Lachlant1984: Hey great April Fools gag. So I take it the keyboard hasn’t been Circuit Bent at all, I didn’t see any case mods in the video. I’ve never owned an SK-1 so please excuse my ignorance. were those awesome synth sounds used in this video actually part of the keyboard’s synth set? I really like those sounds. I know I’m in the very small minority here but personally I really don’t like Circuit Bending at all, and there are a few reasons for this.
  • Gant-Man Garrard: I had an Sk-1 when I was 6 years old! LOL! This was back in 1986! Good keyboard sounds and it had a sampler!! All it needed was midi.
  • vanhalter: I was joking! I know that these sounds are recorded with the sampling… Regards from Italy CIAO
  • Raunchola: And you still won’t have them! 😉
    Check the uploading-date
  • vanhalter: I have casio sk1, but I don’t have these sounds!
  • futureimage: Check the date 😉
  • Tara Busch: Very nice!!! ; )