Build your own synthesizer with keypad note inputs and knobs for parameter controls! At the heart of this instrument is the DSP-G1 MIDI synthesizer voice chip — an analog modeling synth by Jan Ostman that can read in MIDI data for notes and control change (CC) messages, and outputs sound to play over any powered speakers, headphones, or amplifier system!
The DSP-G1 makes beautiful, classic paraphonic synth sounds, similar to the famous 1980s Roland Juno-6. You can play up to five notes at once, each with three oscillators, and you can dial in multiple wave shapes, detuning, LFO, 24db filter, ADSR envelopes for the amplifier and filter, and more!
The Feather M0 Express can read your Trellis keypad buttons and potentiometer knobs and then send these commands to the synth chip as MIDI messages.
The Trellis Feather DSP-G1 synthesizer code is configured to play eight note scales in three octaves, in both momentary and held (latching) modes, with the bottom row of eight keypads reserved for input functions. But, there’s nothing to stop you from turning it into a step sequencer, random note generator, chording machine, or who knows what!
You can watch the build from the livestream here:
In addition to the parts above, you'll also want a cardboard box, roughly 9"x6"x3" in size to use as an enclosure.
Tools required are a soldering iron with solder, box cutter or hobby knife, diagonal cutters, and a pair of wire strippers. You may already have these, but if not, here are some suggested tools: