Ieaskul F. Mobenthey Eurorack Modules From Ciat-Lonbarde's Peter Blasser

via Control

"Peter Blasser's - Ieaskul F. Mobenthey modules are now In-Stock. Couldn't be happier to have Peter's stuff in-stock, he's been pushing the limits of instrument design and the philosophy behind it for years with Ciat-Lonbarde and very much encompasses the ideals of what we find inspiring about synthesis, electronics and the makers who make them. Limited Qty available."

Details on each, captured for the MATRIXSYNTH archives, follow. You'll find a video of them previously posted here.

"Ieaskul F. Mobenthey - Denum

The Denum module is essentially a bounds/bounce oscillator. It has the “triangle core” circuitry used in many
oscillators, but it adds a correlated bounds modulation, according to the concept (see below). Here, bounds and
bounce are each given equal treatment, with separate linear and exponential controls and inputs. In addition,
this module has a fully featured bi-polar VCA with complimentary inputs, to get you quickly going sending
“bb-objets” out the left and right channels.

Denum is an 8HP Eurorack module that runs on +12 and -12 volts. Attach power connector positive to “+” and
negative to “-”. Failure to follow proper power polarity will result in instant destruction of unit.

Looking at the front panel of Denum, note that inputs are marked by copper fill. There are three main sections:
bounce, bounds, and the VCA. Bounce is above bounds to emphasize the numerator/denominator relationship
of the two. Each of the two has exactly the same inputs and knobs. The “basis” knob sets the base rate or
position for bounds. There is a linear control input, marked by a a caret. Linear modulation is an alternative
input for pre-enveloped audio, since it has no attenuverter. However, the exponential control input is tied to an
attenuverter, marked by a characteristic bow-tie. An attenuverter works like this: at noon the modulations are
nulled out, they have no effect; clockwise from there they increase in intensity, with positive input meaning
“more”; to the counter-clockwise direction, modulations increase as well, but with negative input meaning
“more”. This knob is essential to controlling how much, and in which direction, your modulations apply.
Between the bounds and bounce areas, there is a range switch. When in middle position, Denum runs at a
standard audio rate. Pointing downward is a low audio rate, and pointing upwards is a definite CV, lowest rate.

The triangle output speaks the position of the waveform in voltage, and square expresses the frequency in terms of
negative and positive 10 volts. The triangle output is bussed into the left and right audio inputs of the VCA,
at bottom. Either can be swapped out for external audio energies, via the “left, right signal inserts”. The “left,
right VCA inputs” are for controlling the amplitude of the signals, with either a linear or exponential mapping. If the
left input is greater than right, sound goes out the “left out”. If right is greater than left, sound goes out the
“right out”. The voltage amount of difference maps to loudness in these channels. The “linear, expo switch”
chooses linear when cocked up, as marked by a caret, and exponential when cocked down, as marked by a
rounded form. There is an optional mute when the switch is in the middle.

About Bounds/Bounce

In porting triangle oscillators to the digital realm, I noticed that it was just as easy to modulate their speed as
it“Sitting at the round metal cofee table, on the deck of my beach house, I cannot tel whether it wil come inland
or stay hovering over the waters; I know it is a storm cloud because of the lightning, extending to space and salt,
exchanging energies.” was to change their boundaries. This is because triangle oscillators are a simple
mechanism: go up until upper bound is reached, then go down until lower bound is reached, and repeat ad infinitum.
Meditating on this idea, it soon became apparent that the two modulations, bounds and bounce, are exactly complimentary
in their effect on pitch; as bounds gets “more” the frequency gets lower, and as bounce gets “more” the frequency gets higher.

Furthermore, pitches can thus be expressed in ratio form, like the musical tuning systems of just intonation;
bounce numerates and bounds denominate. On a computer it became an aesthetic imperative to program using
only the “int” number set, forming an alternative to the “float” number system. Porting the concept back to
analog electronics does not preserve the integers, of course, because here we are dealing with flows of gray
again, but it preserves intact the modal philosophy of “bounds/bounce”. Thus most triangle oscillators are only
“bounce modulating”, but here we have a new sort of “bounds modulation,” for the palette, that acts in a
different way from the typical. To illustrate, imagine modulating the speed of a triangle wave; you can change
it at any moment in time, in continuous intervals. Bounds, however, can only be modulated at the moment they
are tested, at top and bottom. Modulating bounds can sometimes have the sound of “sync lock” and the
associated undertone series heard in primitive electronic “555” circuits. However, the abstraction of bounds
modulation provides for more subtle, inharmonic possibilities and combination with traditional bounce
modulation gives the end user a confident stab into the realm of infinite possibilities.

Difference from Swoop

In all bounds/bounce modules, oscillation has a place in space, through positive feedback, as well as place in
time, with negative feedback. It is the relationship of the two that determines its frequency. Swoop and Denum
both manifest this concept, but you could say that Swoop is more for controlling, enveloping events, and Denum
is more for continuous waveforms, although Ieaskul incites you to think differently from this modus.

The main thing to remember with Denum is that modulations are mapped entirely symmetrically across bounds
and bounce. Both have a linear input and exponential input. We all know what exponential bounce is; the
source of one volts per octave scaling achieved by adjusting the attenuverter just so. But because it goes from
top down, how can exponential bounds control “work”? Well, it turns out to be just as robust; no frequency
band is over-played across all input voltages. To describe it: low voltages result in infinitely high frequencies,
and going down you need to go slowly because it is transitioning from “very high” down to a normal range, and
there are a lot of frequencies to cross! And then the transfer function can start going faster because the effect on
frequency is less in lower frequencies. It's hard to understand in analog, so let's try thinking about it in
numbers, as an emulation. Imagine using just intonation, with ratios to specify frequency. 1 to 2 is an octave
up. 1 to ½ is an octave down: big changes. But 2 to 3 is the same distance as ½ to 1/3: a musical fifth. Extend
this system out and you see that everything gets tighter whether going from 32 to 33 or 1/32 to 1/33. That is
why exponential control can and “should” be applied to both bounds and bounce.

Noting that the Swoop module allows you to control the top and bottom bounds separately, Denum does not
take raw inputs for them, but converts control voltages in a manner complimentary to bounce; it is the tonal
effect of this complementarity that distinguishes it from Swoop. Turning the “bounce basis” knob up, as would
be expected, brings the pitch up. Turning the “bounds basis” knob up, on the other hand, brings pitch down. It
also manifests a change in the amplitude of the triangle wave, such that high sounds are quieter and low sounds
are louder, thus mimicking the primitive effect of a low-pass filter and the general aesthetic concern for loud
bass and un-ear-piercing highs. Rest assured, however, that this is not an “aesthetic” design dongle, but a strict
adherence to the new-materialism dictum of letting the circuit speak.

Technical Details

» Eurorack Format
» 8HP Panel Width
» Skiff Friendly

The Denum User Manual can be downloaded HERE.

Ieaskul F. Mobenthey Headquarters can be found HERE."

"Ieaskul F. Mobenthey - Fourses

The Fourses module consists of four bounds/bounce oscillators, stacked on top of each other so that their
bounds are mutual. Imagine four bouncy balls in a greased perspex tube only wide enough to permit them to
travel along it. They bounce off of each other in the tube, and generate intricate but inter-related chaotic
outputs. Each bouncy ball has the requisite basis and attenuverter knobs, and bounds inserts, control input, and
triangular output.

Fourses is a 12HP Eurorack module that runs on +12 and -12 volts. Attach power connector positive to “+” and
negative to “-”. Failure to follow proper power polarity will result in instant destruction of unit.

Looking at the front panel of Fourses, note that inputs are marked by copper fill. The four operators are exactly
the same in appearance. The bounds of any operator are dictated by the ones immediately above and below,
except for the very top and bottom operators; the top upper bound is set to eight volts, and the bottom lower
bound to negative eight volts. The bounds of any operator, however, have inserts that you can use to manually
set a boundary to whatever voltage you wish. This may introduce Ieaskul's masthead, the paradox wave, that
comes about when a lower bound is greater than an upper bound, causing the oscillator to go into hyper
oscillation since it cannot rest in any stable zone.

Connected to the bounds inserts area, there is a rate knob that acts in a special, Fourses-like way: knob in
middle causes the up- and down- slopes to be equally fast, and the operator will bounce easily; turn the knob
clockwise and it will have a very slow down-slope and a fast up-slope, counter-clockwise is the opposite. The
philosophical reasons for such a knob came about when testing the original fourses; control of slope symmetry
is just as important as, or perhaps more important than, control of frequency in Fourses. The control input, with
associated attenuverter also controls frequency and symmetry in the same way. An attenuverter works like this:
at noon the modulations are nulled out, they have no effect; clockwise from there they increase in intensity, with
positive input meaning “more”; to the counter-clockwise direction, modulations increase as well, but with negative
input meaning “more”. This knob is essential to controlling how much, and in which direction, your modulations apply.
The “position out” can hardly be called “triangle out” anymore, but it is the same electronically
as would a triangle output- a reading of the current position of each bouncy ball.

For each operator there is a range switch. When in middle position, the operator runs at a standard audio rate.
Pointing downward is a low audio rate, and pointing upwards is a definite CV, lowest rate.

History of Fourses

Fourses was originally released by Ciat-Lonbarde in kit format, around the time of the Bush-years. It had two
of the “greased perspex tube” formations, plus some interstitial circuitry called the “intersexon”. Ieaskul is
considering putting out an expansion module to create this intersexon between two Fourses modules, but you
could probably cook up a recipe that would be very similar with stock Eurorack sample-and-hold modules;
simply trigger a sample of one Fourses by another Fourses, and make these step-like signals available again for
modulation. The thing that is hard for a Eurorack system to mimic, is how the intersexon used current mirrors
on the outputs; outputs thus would mix in a unique, non-ohmic melange of competing current sources.

Eurorack, and the modular philosophy in general, does not condone modulation by current vector, only
preferring outputs to be voltage in series with a 10k resistor. Actually current mixing could be an interesting
route to explore for modulator-masters, but it is a subtle region. It was only brought about because the Fourses
was a touchable instrument, having about 156 brass nodes sticking up out of a wooden case, that could be
patched by both wire or flesh, or even a living worm. It was part of a general exploration of mixing signals to
use current as one source of output electrons.

Another inspiration was the circuit-bending movement, and the use of innards of circuits, exposed to musical
touch. Thus, Fourses was an instrument designed to be bent, and it did this by bringing the interior, “soft-like”
parts of each oscillator out. The two most important would be called the “capacitor tank,” and the “hysteresis
node,” which correspond directly to the bounce/bounds dialectic as well as that of the triangle/square. You see
any triangle oscillator has an accumulator of analog slope, using a capacitor to make angled segments; and a
bounds tester, comparing against a fixed (or not so fixed) measure. Since the capacitor tank deals mostly in
current anyway, this was a good tip-off to make current-nodes in the overall design.

In bringing back the Fourses, ten years later, all these touch-operable features were explored in numerous
prototype paper-circuits, and they worked as in the original. However, the Fourses modular does not include
such extended touch-features, because it is a redundancy on top of the central concept; Fourses itself is a
modeling of a sort of inter-related touch web, by having each oscillator “touch” the other. It is a morphic
resonance to put a “touch” oscillator inside a “touch” case, but perhaps the use of the Fourses primitive as
source of chaos could be distilled down into a small form factor with complete voltage control and range
switches, to interface and scramble all sorts of other modules with its manifold outputs.

Perhaps in the future we could bring back the touch-Fourses, but Ieaskul is confident that fitting it into the
Eurorack standard is a happy compromise to bring its unique sounds and gestures to “Europe”.

Trying to keep with original idea:

» A sound of closely tuned oscillators bouncing off of each other, chaotic fuzz. If the operators share a
similar frequency then they become indistinguishable, like bosons.
» Far tuned oscillators including low frequency ones brings out grains, striations, or beats in the texture.
This is why tuning symmetry and frequency at the same time is important: slopes pointing away from
each other create harder boundaries.
» Intersexon provides a counterpoint, or better yet “motif b” for the instrument. Now this is out sourced to
the Eurorack consortium.
» Sandrodes are nodes that are highly touchable. they are hard to implement because they represent both
input and output: the instrument has to be tied up, but have a highly sweet “ground state”... it is the
action of crossing all these nodes that changes its state, ties it up more, making touch sensitivity,
wireability…
» "goal based design” --- tansas city station --- transmitter > noise > receiver

Technical Details

» Eurorack Format
» 12HP Panel Width
» Skiff Friendly

The Fourses Manual can be downloaded HERE."

"Ieaskul F. Mobenthey

The Swoop module is essentially a bound/bounce control voltage processor, in the lineage of such multi-purpose
tools as the “Serge Dual Universal Slope Generator”. Like that module, Swoop responds to:

» Input voltages that set target boundaries in voltage
» Control voltages for angle of both the down and up segments of the waveform
» Trigger voltages that perform a single “swoop” up or down.

It differs, however from the DUSG, in that it truly is a free-running oscillator, that will bounce between any
given boundaries; bounds take a more correlative role in deciding the frequency. In fact, it is already running
when given zero input, bouncing infinitesimally at a very high resultant frequency.

This oscillator was conceived as a sort of triangular answer to the operation of filters, that take an input and resonate damp.
Damping, in Swoop, results in an ever higher and higher frequency, thus fulfilling the bounds/bounce concept.
Inspired by the idea of polarity, there are actually two triggers, for upward swoop and downward swoop, or
even both ways consecutively.

Swoop is an 8HP Eurorack module that runs on +12 and -12 volts. Attach power connector positive to “+” and
negative to “-”. Failure to follow proper power polarity will result in instant destruction of unit.

Looking at the front panel of Swoop, note that inputs are marked by copper fill. The two bounds inputs each
control both upper and lower boundaries. They do this by rectification. With no connections, they are set at
zero, and thus as mentioned already, oscillator is squeezed into this infinitesimal space. If one connection is
made, the oscillator will bounce up and down between zero and the voltage, whether it be positive or negative.

Likewise, with two inputs, the oscillator bounces between whichever is highest and whichever is lowest.
Up in the bounds zone, there is a range switch. When in middle position, Swoop runs at a standard audio rate.
Pointing downward is a low audio rate, and pointing upwards is a definite CV, lowest rate.

The triangular output is the position of the wave, and square is the mechanical signal to go up or down, a good way to
hear its frequency. The bounce section is a very standard sort of analog math block. There is a bounce “basis” knob
for both down and up slopes, to set the base rate. Above it, there is an attenuverter, marked by a bow-tie, to process
the modulation inputs, at top. In addition to the downand up inputs, there is a “both” input,Sitting at the round metal
cofee table, on the deck of my beach house, I cannot tel whether it wil come inland or stay hovering over the waters;
I know it is a storm cloud because of the lightning, extending to space and salt, exchanging energies.”
in the middle for convenience.

That input feeds into both the down and up inputs, which have separate attenuverters. An attenuverter works like this:
at noon the modulations are nulled out, they have no effect; clockwise from there they increase in intensity, with positive
input meaning “more”; to the counter-clockwise direction, modulations increase as well, but with negative input meaning
“more”. This knob is essential to controlling how much, and in which direction, your modulations apply.

At the very bottom of the module is the triggered swoop section. As mentioned above, there are two swoops,
negative-going and positive going. The trigger responds to a positive transition, crossing one diode drop above
ground (one volt). This should work with pretty much any gate signal but also analog signals larger than two
volts peak to peak. The outputs here are gate signals, from zero to twelve volts, indicating that the swoop has
finished its duty cycle. These can be used to trigger the other swoop to make a chain of different polarity
swoops, or connected in “x” formation, generating a continuous oscillation. To make a recirculating positive
swoop, you can connect its output to its input, likewise for a recirculating negative swoop. The analog swoop
voltage is “read” at the triangular output, up top. They cause the signal to travel once to the eight (or negative
eight) volt mark.

Lineage of Swoop

I guess I first worked on swoop in the Dogslit, and the associated Conrad Papers. These were all paper circuits,
originally designed for controlling the light boxes of Dan Conrad. Each swoop was like a unit cell, creating this
triangular event, and then triggering another swoop; montages of loops and other topographies could be
constructed from multiple swoops. These then controlled a Dogvoice (to be released by Ieaskul in Eurorack
form); the multiple overlapping events resulted in unpredictable growls and barks, like how a dog wants to think
nomadically.

There were swoops and anti-swoops, meaning some went up and some went down. Physically the circuits were
separate. Around this time I realized how much they paralleled the DUSG, and how Serge musicians will use
that module as well to create montages of cellular units that trigger each other.

Fast forward about six years, at the development of the Shnth device, a digital synthesizer. It used an internal
language to process, and indeed emulate analog functions. The opcode “swoop” was designed to enable
granular synthesis with triangular events, but it also happened to emulate the primitive piezo flex gesture: press
down and release result in an upward swoop immediately followed by a downward swoop. It worked this way
in the default “dirac” mode, or using signed math. But it also had an “arab” mode wherein swoop operated with
just one positive going triangle. It so happened that signed math generated this unique “double bubble” sound
from the positive swoop to negative swoop crossing zero.

There was one more purposing of the term “swoop” in code, as a synthetic response function for enemy chubes
in the game “Mikey Walker”. Chubes respond to punches by wobbling and then falling if punched in time with
their resonance: that's the aim of the game. So I was seeking to provide another type of response than the
standard (but totally wonderful) resonant filter. In a separate chapter I can describe how I used Anthony
Braxton's tri-centric logics as a brainstorm for the idea of using a triangle wave as a resonant filter. Essentially
it needs to have an input, not a modulation input but an input as like a filter, and it needs to damp energy down
by oscillating it. Of course, when a triangle wave gets bigger and smaller its frequency changes, according to
the bounds/bounce concept; this helped enrich gameplay with a new resonant strategy for enemies.

So in Ieaskul's swoop, we have several threads of analog, emulation, and conceptual coming together in one
module. There is biphasic support, swoop and anti-swoop are not separated anymore; but along with signed
math also comes unsigned math. There is the emulation of gestural flex, in Newton's own “equal and opposite
reactions”. And there is the possibility of a “resonant triangle” and what happens when it is damped: Ieaskul's
masthead, the paradox wave.

Swoop User Manual can be downloaded HERE.

Ieaskul F. Mobenthey Headquarters can be found HERE."

"Ieaskul F. Mobenthey - Sprott

The Sprott module is a model of chaotic jerk system with standardized voltage control of all parameters. Thus, the chaotic attractor can be shrank down to distill the module into a resonant filter that is the dynamical sub- circuit underlying most jerk systems. It is named after J.C. Sprott who has published numerous papers, articles and books on chaos and chaotic circuits, from a rigorous physical view-point. This module is of course for musical purposes; although the voltage control feature has limited import in physics experiments, it is crucial to aesthetic purposes.

Sprott is an 8HP Eurorack module that runs on +12 and -12 volts. Attach power connector positive to “+” and negative to “-”. Failure to follow proper power polarity will result in instant destruction of unit.

Sprott has three integrators and one “signum” non-linearity, according to the simple differential equation, “0 = ax''' + bx'' + cSGN(x) – dx”. In re-structuring the circuit to fit voltage control guidelines, the use of transconductance amplifiers offers an experimental input to change the subtle dynamics of this system: by modulating their linearizing diodes, paradoxically adding to non-linearities available. The module is thus for experimentation, but it can always boil down to a simple resonant filter, perhaps this is its power, in going out and coming back to a basic regime. Since any differential jerk equation is highly dependent on “initial parameters,” Sprott has a dedicated VCA on the input.

Use of this VCA can help inform use of the other three sections. Looking at the front panel of Sprott, note that inputs are marked by copper fill. For any section there is an “in” and a “diode”. The in inserts signal energy directly into that portion of the differential equation, with the VCA inserting directly into the high-pass. It should be mentioned, however, that inputting into one section will affect all; they are not separate filters but all inter-connected as per the equation. The diode is the least explainable of all inputs, but just note that a higher voltage here will in general bring the frequency down, but it should also bring it into a more linear mode of operation. As Ieaskul said, it is experimental. The VCA has a basis knob, on the left, which sets a basic amplitude for its input. It then has the VCA control input and associated attenuverter which modulate it furthermore.

An attenuverter works like this: at noon the modulations are nulled out, they have no effect; clockwise from there they increase in intensity, with positive input meaning “more”; to the counter-clockwise direction, modulations increase as well, but with negative input meaning “more”. This knob is essential to controlling how much, and in which direction, your modulations apply.

For each section, there is an output that reflects one part of the differential equation, in the natural order it is built in circuitry. So, from top-down, there are high-pass, band-pass, low- pass, and finally, chaos-pass outputs. Each section has it's own range switch. When in middle position, the section runs at a standard audio rate. Pointing downward is a low audio rate, and pointing upwards is a definite CV, lowest rate. They are separated for experimentation purposes, however standard operation is to have them set at the same range- all up, all mid, or all down.

The next section is labeled, “Q,” meaning voltage control of quality, or resonance. It has a similar “in,” “diode,” “control,” and knobbage structure. The “Q” is highest when this knob is down, and that can cause saturation of the waveform allowing experiments in distorted filtering. For sweet filtering purposes, turn “Q” up later than noon.

The next section down is labeled “FR” for “frequency”. Here is where the general time-dependance is modulated, also known as “cutoff” in filterland. It too has a similar knobbage/jackage structure.

Finally the bottom section is devoted to chaos, through control of the “third integral”. It has a similar jack structure, and it should be pointed out that the knobs control how much chaos is inserted back into the dynamic. With its basis knob all the way down, Sprott should return happily to filterland.
To read more about Jerk Equations, please consult J.C. Sprott's massive corpus of publications at:
http://sprott.physics.wisc.edu/pubs.htm

The Sprott Manual can be downloaded HERE.

Ieaskull F Mobenthey headquarters can be found HERE."