Hey there!
I am trying to set up a duophonic patch, and I would like one oscillator to always play the highest, and another one to always play the lowest pressed note.
I think there is a module that puts out highest and lowest pitch from a polyphonic signal, but I can’t find it and don’t remember what it was..
If you’re playing it from a keyboard or other MIDI input source, I would advice just using 2 monophonic MIDI modules, one with high and the other with low note priority. If not, indeed you might need some sorting module or other. Can’t think of one off the top either.
Perhaps this?
This old thread might help:
Oh that was quick, thank you!
Count Modula Polyphonic Min/Max seems to be what I was looking for, but using two MIDI-CVs seems like a really good solution, too.
Both work, the solution with two MIDI-CVs is the better choice for me right now, since it plays like a 2-voice paraphonic synth and falls back to one pitch if only one note is pressed, which is what I wanted to do.
My Poly Prune can sort polyphonic signals. Just set the desired sort order (can sort input, select, or output - doesn’t matter which), keep the knobs at defaults, patch poly IN input, and get sorted result at OUT.
It can also select a subset of the channels (prune away unwanted channels). So you could have N incoming, and you only want the lowest and highest values. Set the Sort to input ascending, the Start to 1, and the Count to -2, and you would get two channels of output with the lowest on channel 1 and the highest on channel 2.
If you wanted the two lowest and two highest values, then change the Start to 2, the Count to -4, and you would then get 4 channels of output in the following order: [2nd lowest, lowest, highest, 2nd highest].
But like you say, I don’t know if this helps your use case.
I am thinking about creating an expander that would preserve corresponding channels from auxiliary poly inputs (with the same number of starting channels), sorted based on the sorted output of the main Poly Prune output. It seems like an interesting idea, but I struggle to see an actual use case.
Nice, glad it helped. Duophonic playing is super fun right? 
Yeah it got it’s advantages for sure, very nice for 2-voice leads or pads, and if you use one of the 2 oscillators for modulating the filter or fm you get some nice intermodulations.