Aleatrons are circuit-bent keyboard instruments.
Their behavior is often erratic and unpredictable. They crash. But they
are also capable of exquisite aleatoric, or chance, musical forays.
The original instrument, a Casio mini-keyboard sounding about as good
as these small keyboards get, sounds quite beyond its class with the
new line output feeding an EQ, reverb and a hi-fi amp or recording system.
In addition, while it would be difficult to make the SA-2 sound like
a full-blown professional synthesizer, the circuit-bending process does
widen the frequency response and some very powerful voices do result.
While I'm still able to locate the no-longer-produced SA-2 keyboard
I will continue to offer a top-end version of this Aleatron.
The Deep SA-2 Aleatron's four chance triggers, each a special push-button
switch coupled with a threshold dial, are used to throw the instrument's
digital logic systems off track. This results in either odd tonal production
or chance musical composition, or both. These aleatoric passages may
be short or long in length, again decided by chance. The effect is often
that of a small, live improv group... piano and drums, perhaps bass,
with an odd accompaniment instrument appearing here and there. Alien
forms of jazz emerge, abstract tone clusters rise and fall... a valid
music mind, though insane, is released.
As is often the case with aleatrons, the behavior of the musical keyboard
is unpredictable. Often there is no response from the keyboard at all.
At other times pressing the keys will alter the music/tones in progress
in various ways. Tones may be pulsed, the key of the music in play might
be shifted, aleatoric production might be modified in numerous unforeseen
ways.
Four body-contacts are wired to the Deep SA-2 circuit. These connect
the player electronically to the instrument. Electricity is then conducted
through the player's body just as it is through any other component
on the circuit board.
Three of these contacts are bridged by the fingers to introduce strange
oscillator tones into the music, raising or falling in pitch depending
upon which contacts are held. Within this alien scheme of music production
these oscillations can be used in real-time for expression, thought
of in the same way as a volume pedal or pitch-bend wheel. Or, if touched
while the instrument is silent, these contacts can be played by themselves
providing theremin-like sweeps of frequencies. Routing this signal through
volume pedal, EQ and reverb will create a dramatic lead voice on its
own.
The other body-contact serves as another chance trigger, like the switches
described before. Here, however, simply touching this small brass ball
while one of the oscillation contacts is touched will advance the aleatoric
patterns in progress. This is a nice way to advance the aleatoric passages
in small and delicate increments.
Other of the nineteen new additions include a reset switch since the
SA-2 crashes often, a speaker switch, a gold-plated RCA line output,
an antique white milk-glass pilot lens with a blue LED inside for a
power indicator, and a red LED flashing inside a small glass animal
eye bulging from the distorted case and serving as a peak indicator.
The instrument is finished with a multi-coat process involving fluorescent
and metallic pigments in combination with laser-etched prismatic dust
and final gloss. New controls designations are hand-inked.
More from Reed's EMI article on the SA2 Aleatron:
"All fields have their hallmarks. My experience with circuit-bending
has, over a period of thirty years, resulted in the development of several
distinct technical categories born of the process, each best represented
by a specific instrument or two. These main categories would include
body-contact control, human voice synthesis, digital samples, the equal-tempered
scale and, lastly, aleatoric instruments. That is, chance composition
devices. I've come to call instruments that produce aleatoric music
through the electronic process of circuit-bending aleatronic instruments,
or the result of aleatronics.
"But how about an instrument that stretched beyond single category and
represented the entire scope of circuit-bending's possibilities? An
instrument that involves body-contacts, human voice synthesis, digital
sampling, the equal-tempered scale and automatic chance composition.
All present and in fine example. That would be a true hallmark instrument.
"Such an instrument exists. This instrument is the Casio SA-2, a small
32-note keyboard with a large set of built-in sounds to work with. There
are thirty-two accompaniment patterns for circuit-bending to reshape.
These include seemingly sampled percussion instruments whose high-quality
recording really shines through, adding a sparkle of live performance
to the countless (re)arrangements now obtainable. A bank of sixteen
instrument voices is also provided. These may or may not be sampled.
They are, however, high-quality voices, most with rich overtones. While
the keyboard is described as only 2-note polyphonic, circuit-bending
seems to change all this. In fact, very complex pitch clusters and orchestrations
result from the new anti-theory electronics.
"A single push-button trigger switch and body-contact are sufficient
to nudge the SA-2's programs into wondrous disarray, resulting in original
composition sequences looking to the five categories above...
"Here the body-contact, rather than implementing pitch-bend or other
frequency shaping as is its function in many other circuit-bent instruments,
is used to advance the aleatoric musical structures. A delicate touch
upon the brass contact increments the rhythmic and tonal frameworks
at the heart of the chance compositions, continually pushing them forward
into new combinations of indeterminate events.
"In the realm of human voice synthesis ... no, the SA-2 does not come
supplied with such capabilities. Still, on a number of occasions, startling
human-like vocalizations arise. Murmurs, chants, shouts and odd singing
might materialize and disappear as the music evolves. The emotive effect
of these shadowy utterances can be powerful and revealing ... a Rorschach
image in sound.
"Digital samples are fascinating to dissect under the diffracted light
of circuit-bending. As mentioned before, the SA-2's percussion sounds
seem sampled, and all voices involve a digital capture scheme that has
them nicely rendered in accessible sound files (probably Pulse Code
Modulation).
"Whereas analog signals tend to deteriorate into static-like decay when
exposed to certain circuit-bending applications, digital signals break-down
into distorted routines rather than distorted tones. The tones can therefore
remain sharp while their harmonic content, envelope and assembly behavior
is altered. Likewise, just as it is with the musical notes, digital
percussion sequences are similarly transformed. Cymbals become backward
gongs, kick-drums blend into bass lines, snare drum decays are frozen
into crystalline seas of sizzling metallic hiss.
"Generally, keyboard instrument = equal tempered scale. The very nature
of circuit-bending places it in the opposite corner of this scheme of
order, from conceptual foundation to vocalizations. Perhaps this is
why the combination of the two conflicting sensibilities can be so catalytic.
Here, within the circuit-bent SA-2, there is created a riveting interface
between these two disparate worlds, elements of the familiar bound together
by an invasive disorienting matrix.
"As mentioned, central to prompting the SA-2's electronics into unique
tonal synthesis and aleatoric music production is a push-button triggering
switch, the most important circuit-bending addition. This switch disrupts
the instrument's program routines. Several choices exist as to where
to connect the switch to the circuit. Any of these will initiate aleatoric
composition. In use, with or without keyboard keys being held down,
and with or without a rhythmic accompaniment playing, the musician quickly
and lightly taps this push-button switch while listening to the results.
"Any number of things may happen. The entire circuit may crash. Silence.
No response anywhere until the main power switch is turned off and back
on. More than likely, the keyboard will become inoperative while the
sound circuit, cautious of the strange knock, decides whether or not
to answer the door. Many knocks might go unanswered. But when this obscure
door does open to the world of anti-theory electronics, I've learned
that anything might appear.
"It could be a haunting voice, a single note of beguiling texture perfect
for capturing as a sample and flying into a full polyphonic keyboard
system. Abstract sounds might come forth ... tangles of sustained noise
and pitch with evolving tonal clusters buried within.
"Pushing the switch might cause a loop to begin. This loop could be
percussion instruments revolving in odd rhythm, abstract sound cycles,
musical notes repeating a melody, or combinations from dense to sparse
of all elements working together. These repeating sound-forms may slowly
fade away, hold steady or accelerate to crescendo.
"Pushing this digital trip-wire will also, every so often, launch an
aleatoric episode such as those described before. This chance composition,
like certain loops, may also slowly accelerate to crescendo ending in
any number of resolutions including tone clusters, silence, loops, pre-programmed
rhythms or, occasionally, a new aleatoric sequence possibly again increasing
in tempo through another complete cycle. The keyboard may or may not
be active during loops and aleatoric passages. If so, it may or may
not behave as usual, sometimes pulsing disassociated notes, producing
sound effects or even modifying accompaniments in progress. c "Pushing
the same triggering switch during aleatoric progressions can shift elements
within the music, altering perhaps the percussion pattern, the choice
of lead instrument, the accompaniment scheme or a number of other sonic
aspects effecting the flow of indeterminate composition. Again, pushing
the button represents a certain degree of risk, not at all unfamiliar
to circuit-bending, that could result in program crash. While it's true
that the lost sound-form is probably gone forever, impossible to achieve
in exactly the same way again, the bending process balances this out
here and in many other instruments by providing a bottomless well of
possibility for yet unheard musics, a chance to give life to new and
unique sonic creations every time the circuit is turned on."
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