I made a polyphonic MIDI interface for Eurorack using Arduino and 3D-printing. I was inspired by CVpal and MIDI Thing, but I implemented a feature-set more focused on my needs.
It has two different polyphonic allocation modes, and two split-keyboard modes with a monophonic algorithm on one side. I also added an additional “logic OR” gate output (useful for single-filter setups) and the ability to “lock” held voices using a button.
But at the end, the main challenge was building it using only 6HP!
Thanks for the feedback @ldezem@sakul If you’ll build this or “In CV”, share the result or send me a message, I’m curious about your takes!!!
Here’s a quick demo of MIDI 4+1 I uploaded today, where I use it together with my alternative firmware for Stages in a 52 HP simple polyphonic setup:
Patch notes, from left to right:
MIDI 4+1 interface allocates notes polyphonically from the keyboard into four channels of CV/gate. The additional top-most gate output is the combined OR.
CVs are sent to Chord v2 in Unison Poly Mode: each oscillator is controlled independently by its own 1V/oct input.
Gates are sent to Stages, which runs a custom firmware (link above) that generates five identical envelopes.
Veils uses four of these envelopes to drive one VCA for each of the four voices coming from Chord’s individual outputs.
WMD SSF Pole-Zero filters the final mix from Veils; its cutoff is modulated using the fifth envelope from Stages, the one triggered by the OR-gate signal.