Toppobrillo Cluster Eurorack Processing Toolbox Module (Silver)

Cluster is Toppobrillo's take on the workflow of the versatile Buchla 200 series control-voltage processor - model 257 - with some marked improvements and options. Missing is the cool equation, but they kept some arrows and replaced the variables with LEDs :) They've also added a voltage-controlled “polarizer” (four quadrant multiplier), an extra processing / mixing channel and routing options that make it an extremely flexible and more compact tool for the dense Eurorack environment.

Cluster is a precision 8HP processing toolbox that can sit anywhere in a system. It has three independent sections that can be used individually or taken as a whole. Up to four signals can be mixed and there is also a complementary sum output. Potentiometers are center-detented for easy tactile centering. Signal path is high bandwidth, low noise and low offset- and is well-suited for both audio and control signals.

Each section can be used independently vis-a-vis independent outputs and a subtractive normalization scheme - this means if you need to grab a crossfader (or just use it as a VCA/ ducker) it’s there, and you’ve still got the polarizer (XY) and another processing channel (Z) mix to work with.

XY (polarizer channel)
The top section is a voltage-controlled “polarizer” or more accurately, a four quadrant multiplier. It multiplies two signals, “X” and “Y” . The X(Y) output is the product of these two sources. Unpatched, the Y input is normalized to an offset voltage, and thus will act as a standard processing channel when unpatched, giving X*1 when fully CW and X*-1 fully CCW. Patching a source into the Y INPUT defeats this normalization, and the “Y AMT” knob will now scale (multiply) the source patched into Y, giving Y*1 when fully CW and Y*-1 fully CCW. This is useful in that it allows the top section to be easily patched as a standard VCA with a positive going CV. A bicolor LED indicates output amplitude and polarity.

A->B (crossfader channel)
The middle section is a linear crossfader. The knob and A->B CV input sum, and select A to B and anywhere in between.
The ‘REF’ toggle, when engaged, routes a selectable offset to INPUT A’s normalization- This allows you to use the crossfade channel as a voltage "mirror", for instance. LEDs indicate the relative crossfade position.

Z (attenuverter/ offsetter channel)
The bottom section is simply another processing channel with an offset normalled to it’s input, acting as a manual offset control when unpatched. Patching into Z defeats this normalization, and Z AMT knob will now multiply the Z input, giving Z*1 when fully CW and Z*-1 when fully CCW. A bicolor indicates output amplitude and polarity.

SUM OUTPUTS
There are two SUM outputs, “∑” and the complementary “-∑” . The SUMs are a summation of the three processing sections. Patching any of the three sections’ outputs independently removes them from the SUM outputs. This scheme allows for flexibility using the channels independently, for example, using Z as an offset voltage someplace in a patch- as well as prevents loopback issues when patching Cluster back into it's self- if, say, for instance you wanted to use XY as a ring-mod and send it to one of the crossfade inputs to have a VCA'd ring-mod, or vice-versa, you won't be adding XY to the SUM twice.