Mono Synth

Experimental Monophonic FM Synthesizer




  • 8 different sound for each preset
  • 6 presets
  • 1 carrier oscillator with pitch tuned in semitones
  • 3 modulation oscillators with adjustable harmonic multiple of carrier frequency, detune and amount of modulation
  • 8 algorithms of oscillator configuration
  • 3 wavetables for all oscillators (sine, saw, white noise)
  • LFO with adjustable rate, resolution, amount, destination on different parameters and 8 different shapes
  • exchange sounds between more Mono FM Synths by SysEx message
  • MIDI native by side connectors, note, CC support, thru
  • MIDI by side connectors – MIDI connector by connecting MIDI Bastl by the side

See Trinity page for more information

Technical details

  • dimensions: 75 x 75 x 55 mm
  • powered by 9V battery, 9V DC center positive power supply or side pins
  • user manual pdf
  • Algorithm and LFO routing infochart pdf
  • latest source code at gitHub in the examples folder of the bastlTrinity repository
  • MIDI implementation table
  • assembly instructions instructable pdf


Václav Peloušek about MONO FM

"This is the first firmware I have written for the first Trinity prototype. It sort of went out of control. From the original idea of having a nice sounding FM synth, it came a long way. I was adding more oscillators and algorithms and it ended up in a lot of overflows, so the CPU was not able to handle it anymore and this limitation is basically affecting the sound. The result is extremely unique glitchy sounds, where the limited computing power is the key factor. You cannot hear clean wavetables anymore, but the ways they interact with each other is really something special. I dont know if people would appreciate that kind of hardcore digital FM synth (maybe I go back and write a clean one, too), BUT I am fucking proud of this one and wanted to release and share it! Its really deep!"