Any budding musician looking for a do-it-yourself project would do well to take a look at ElectroTechnique's TSynth — a freshly-launched, open source programmable, and polyphonic synthesizer built around a Teensy 3.6 microcontroller.
"TSynth is a low cost, highly capable, six note polyphonic synthesiser that you build yourself," ElectroTechnique explains of its latest design. "It can store and recall patches, and is controllable via the front panel or MIDI (CC, patch recall, pitch bend and modulation wheel.) It can accept MIDI via a USB Host port (plug your MIDI Class Compliant keyboard directly in), USB Client (appears as a MIDI device on a computer for your DAW) and classic MIDI 5 pin DIN."
"You will be surprised at the range of sounds and the capabilities of TSynth! It is all running from one Arm Cortex-M4F MCU running at 180MHz (or overclocked) and in use, you will find it works reliably with the firmware supplied by ElectroTechnique. It's features rival many more expensive desktop synths, but remember it is supposed to be a fun build using just one microcontroller and not an alternative."
In kit form, the TSynth comes with a front-panel circuit board, finished in eye-catching red, a main PCB with the surface-mount components already soldered into place, and a 3D-printed stand-off for the display. Those looking to build it up will need to supply the other components in the bill of materials (BOM) themselves: A Teensy 3.6 microcontroller board, audio board add-on, 33 potentiometers, a rotary encoder, seven buttons, a display, and various connectors, plus any parts desired for an optional housing.
More information on the TSynth itself can be found on the ElectroTechnique website, while its source code and mechanical design files are available on GitHub; the kit itself can be purchased from Tindie for $33, with the total cost of the parts for a finished build estimated at around $99. A version of the kit compatible with the newly-launched Teensy 4.1 is planned for later this year.