yawetaG wrote on 2020-07-22, 15:08:Even when using vintage Yamaha FM modules from the same family, patches cannot always be moved from one synth to another without changing some settings.
Yamaha had two "main" families of FM chips - OPM\OPN and OPL. All OPN chips have the same set of FM parameters and their patches are compatible with each other. OPM FM parameters are mostly same as OPN, only differs by some rarely used parameters and its patches can be easily converted to OPN and vice-versa.
OPL was initially a low-cost FM chip with only two operators and less precise FM parameters. In OPL2 the ability to use other waveforms than sine was added. OPL3 added new waveforms and 4OP mode. All OPL patches are backwards-compatible.
There are also MA family of soundchips used in cellphones. If i recall correctly, they have OPL3-like FM parameters. So, in theory, the OPL3 patches can be converted for this line of soundchips.
cyclone3d wrote on 2020-07-22, 15:43:And why do you need it to be a DIY build?
I do not know any commercially produced GM-compatible FM synths. Even if such thing exist, in will cost too much.
cyclone3d wrote on 2020-07-22, 15:43:What exact Yamaha chip are you wanting this synth to have?
YMU762 (MA-3) would be ideal, but there are very little information about it, because of that, there almost no projects, that use it. There are one project based on YMU762 (the page in Russian, but you can use the machine translation), but it don't have MIDI in and can only play SMAF or MIDI file from microcontroller memory. The author of this project said me, that, in theory, the MIDI in can be added. But my programming skills sucks, and i can't do that. Also, the instrument bank loading for MIDI is also needs to be added, otherwise MIDI will be playing only with built-in (2OP and not very good sounding) instrument bank.
More realistic option is YMF825 (SD-1). But only project i was able to found is this. But it's only a sample code, not a full-fledged synthesizer project, as i earlier said, i'm afraid, that its MIDI implementation would be too "quick and dirty". Also, i don't know, if there any instrument editor for this.
Most realistic option would be dual YMF262 (OPL3).
cyclone3d wrote on 2020-07-23, 04:44:So like a MIDIbox FM except with at least 3x YMF262 chips instead of just one? That would be one crazy setup.
http://www.ucapps.de/index.html?page=midibox_fm.html
I thought, that MIDIbox FM support only one OPL3 chip. I'm a litte confused, it's possible to connect more than 1 OPL3 chip to MIDIbox?