Custom Granular Synth Groc is Raspberry Pi Powered

Raspberry Pi
(Image credit: Oddment Audio)

The Raspberry Pi is no stranger to the world of music having become a popular choice for many artists looking to create digital synths. Today we’re taking a look at another cool synth project that uses a Raspberry Pi known as Groc. It’s shown using a Raspberry Pi Compute Module 4 (CM4) in the demo and was created by a team named Oddment Audio.

According to a recent post shared by the team to Reddit, Groc is still a work in progress. That may be the case but enough progress has been made to pull off a demo that we think is cool enough to share. It has all of the tools necessary to draft something from scratch including a display with an interface.

In the demo video, we get a good look at the module and how it operates. There are 18 center-lit knobs that glow with blue LEDs. These are used to alter and mix sound effects on the synth. The video shows a simple loop made from an audio sample of a guitar riff. The knobs allow you to adjust parameters like the attack, decay, release and sustain speeds.

These illuminated knobs are rotary encoders that can also be pressed as a button. They are mounted to a custom PCB that also sports a speaker and small screen. The PCB is connected to the GPIO of a CM4, specifically the GPIO breakout of the CM4 IO board. This means that a CM4 is not essential for the synth to operate. We could also use this board and code on a Raspberry Pi 4, or even a Raspberry Pi Zero 2 W.

As far as software goes, Groc is designed to use a custom graphic interface. This outputs a visual GUI to the display screen showing critical elements like an audio visualizer as well as indicators for what the knobs are changing and to what degree. You can get a good look at the GUI layout in the demo video.

If you want to get a closer look at this Raspberry Pi project, check out the original post shared to Reddit for more details. Be sure to follow Oddment Audio for future updates on this cool custom synth.

Ash Hill
Contributing Writer

Ash Hill is a contributing writer for Tom's Hardware with a wealth of experience in the hobby electronics, 3D printing and PCs. She manages the Pi projects of the month and much of our daily Raspberry Pi reporting while also finding the best coupons and deals on all tech.