Dexy is a 10HP Eurorack module that does FM synthesis using a Raspberry Pi Pico. It is not a Yamaha DX7 clone, but it uses similar operators and algorithms to create a single FM voice.

It has pitch and timbre modulation, onboard patch storage, and a USB connection that talks to custom patch editing software.

Dexy is part of my homebrew Eurorack synthesizer. Hardware and software are open source. GitHub repository is here.

Features

• Single FM voice loosely based on the Yamaha DX7’s 6-operator voice architecture
• Inputs:
  • Gate
  • Pitch (1V/octave)
  • Pitch modulation
  • Timbre modulation
• Gate and 1V/oct inputs can be normalled from the Eurorack bus (jumper-selectable) – more info here
• Attenutators on the modulation inputs
• Timbre control knob
• Rotary encoder and OLED display for patch selection and note animations
• RP2040-based microcontroller module (similar to Raspberry Pi Pico)
• USB connection to download patches and firmware
• Computer software for patch editing, with live updating to the module over USB

Hardware

Firmware

Software

Patches

There are some patchbank files here. A patchbank can be downloaded to the Dexy module using the DexyPatch software.

License

The Dexy module is open source hardware. The hardware design is published under the Creative Commons Attribution license. Firmware and software are published under the MIT license.