Demonstration of the Erthenvar Patch Chord Eurorack module

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Demonstration of the Erthenvar Patch Chord Eurorack module available at erthenvar.com. Functionally, the module is somewhere between an oscillator and a waveshaper – and also can be described as a bank of two octaves of oscillator controlled oscillators

The Erthenvar Patch Chord is a bank of 25 “Oscillator Controlled Oscillators”, which can be used to generate chords in a Eurorack system.

The Patch Chord continously samples the cycle duration and duty cycle of the input waveform. It outputs 12 semitone steps above the input note, 12 semitone steps below the input note, and the root note itself (available from two output jacks). All outputs are pulse waveforms with continuously variable pulse width.

An oversized tri-color LED spans the color spectrum in each octave, so each note has a unique color! The input jack is passively multipled to an output jack so the visual effects of the LED can be had even if the module is not part of the current patch.

There four modulation types available, each with an input jack and a three-position switch. The switch can turn off the modulation, allow the CV value to control the parameter, or turn on the modulation. The modulation jacks are all DC coupled and respond to audio rate signals, though the tracked waveform has a lower limit of around 20 seconds per cycle.

1. The SQR modulation forces the tracked duty cycle to 50%, making all of the 25 outputs into square waves
2. The INT modulation changes the relationship between each output from a semitone step to an integer or harmonic step
3. The ZERO modulation resets all of the output counters to 0, similar to a sync function
4. The HOLD modulation stops tracking the input and keeps the last counted cycle duration and duty cycle values

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