octoTron

Polyphonic Teensy 3.6 Synthesizer with MIDI Control

This project implement a Teensy 3.6 based Synthesizer with two MIDI inputs.

The Synthesizer has the following characteristics:

• eight voices
• two LFO (sine,sawtooth,square,triangle) per voice
• two VCO (sine,sawtooth,square,triangle) with multiplier per voice
• one 12dB VCF (lowpass,highpass,bandpass) per voice
• one AHDSR generator per voice
• keyboard velocity
• glissando effect
• arpeggiator effect (three tone chord, major/minor, up/down, variable speed)
• one MIDI input for a MIDI keyboard
• one MIDI input for a MIDI controller like https://github.com/ErikDorstel/midiKnobs

The project uses the Teensy Audio Library to implement the synthesizer components like VCO, LFO ... . This graphic shows the connections of the components used.

The octoTron source code uses a new feature in the audio library. To restart an LFO with an absolute phase angle, the file synth_waveform.h must be changed. This pull request contains the changes needed PaulStoffregen/Audio#275 .

The hardware used is very similar to https://github.com/ErikDorstel/stringFlow . The only difference is the use of a second MIDI In port. The octoTron Synthesizer use this second MIDI In port to connect a MIDI controller. The assigned MIDI controller numbers and the schematic are part of the documentation.

Example Video