Swedish engineer Johan Von Konow has developed an open source synth that can be built for as little as $6. The project, dubbed LEET, started out as an idea to develop a synth using a 3DPCB – where wires are arranged in 3D-printed channels – but he quickly realized that it would be better to create a modular system instead.
His device, or rather family of devices, consists of a keyboard, drum pad, chord keyboard, arpeggiator, and step sequencer. Each key (button) has a corresponding RGB LED to enable playback visualization, and modules use the MIDI protocol for communication. This allows them to be used as inputs or outputs, interfacing with digital audio workstations (DAWs) like Ableton or GarageBand. LEET is compatible with Windows, macOS, and Linux (including Raspberry Pi), and can even be connected to Android and iOS phones for a fully portable setup.
Control of each unit is via an Arduino Pro Micro board, which accounts for the bulk of the keyboard’s low BOM cost. The sequencer will require a bit more cash for the LED matrices used, as well as a microSD card reader, tacking on another $19. Full documentation for the LEET keyboard can be found here, and Von Konow plans to publish the same sort of info on his other devices in the coming weeks!