FM synth patch inspired by Yamaha’s classic YM2413-based PortaSound keyboards of the 80’s.
A while ago I bought a used PSS-270 and thought it would be nice to have access to some of the sounds on the Organelle I hacked together a simple patch based on some code I found for emulating the YM2413 sound chip. TBH, it’s a bit rough around the edges, but seems to be doing its job! (I had originally intended to clean up the code and add some more features—maybe even “proper” editing of sounds—but I’ve been too busy lately and maybe someone will find this useful.)
Like the keyboards that inspired this patch, it only allows you to choose between a number of preset sounds. They can be found in the “patches.txt” file.
Each preset sound is a separate line: “Name\Â of\Â Sound” followed by 8 numeric values and a semicolon at the end (not necessary for the last sound).
As an example, the PSS-140 patches found in https://www.nesdev.org/wiki/User:Ben_Boldt/YM2413_Patches would be converted into https://gist.github.com/chrka/26d52153306e82400de62163314fb996 . Note that these are potentially copyrighted sounds and are only provided as an example of the format.
(I recently found out that there is an excellent emulation by Plogue of this class of devices already which I recommend taking a look at, especially if you’re interested in the drum synth capabilities of the YM2413, or just want really accurate emulation: https://www.plogue.com/products/chipsynth-portafm.html )
Controls:
Knob 1: Select preset sound.
Knob 2: Transposition.
Knob 3: Stereo widening.
Knob 4: Cutoff frequency. (The YM2413 has a _very_ “crunchy” sound, the reference schematics have a 3Â kHz lo-pass filter which sounds about right to my ears.)
The “standard” Organelle sequencer can be found in the Aux-menu, as well as an option to turn on Sustain for the envelopes (usually it increases the release, but for some sounds it can actually decrease it instead.)
Acknowledgements:
• The YM2413 emulation is based on Mitsutaka Okazaki’s emu2413 emulator.
• The included presets are based on the work of David Viens and Hubert Lamontagne (https://github.com/plgDavid/misc/wiki/Copyright-free-OPLL(x)-ROM-patches)
• C&G:s library is used for managing shortcuts etc.
Thanks for this! I had a similar or maybe the same Yamaha many years ago. Perfect dungeon synth fuel!