@rbxbx I don’t want to share the code. Not because I consider it a secret but rather because it would mean that I need to clean up the code, which is quite disorganized at this point. Hope you understand.
The synthesis is very simple, though. The short notes are all sine or saw waves that are folded at moving thresholds. The sustained notes are pure frequency modulation, partly with very high indices. At some points I’m applying ring modulation on the main mix.
I’m using changing harmonic grids on the buttons all based on intervals in just intonation. For example stacked pure thirds on the horizontal rows and stacked pure fifths on the vertical rows. Each lit led causes a pitch. It’s the rather big density of pitches which causes the somewhat special timbre, not so much the synthesis.