So here's a cheap trick, which might not be all that useful, but it does a thing on the 49-key Hydrasynth. One oscillator goes to the low octave, C to C, one oscillator goes to the high octave, C to C, and a third covers the middle. The main trick is using keytracking to play with the level of a quantized envelope, and that takes care of the upper and lower octaves. The more boring middle section leverages keytracking and silence in the wavescan. Because the oscillators are split it's a little easier to have separate weird sounds, and you can adjust the range of the upper and lower octaves down to nothing, but it's not really the ideal way to split anything and it's really only for people who stay up too late. The file's in the Facebook official group if you want it.
