Glitchy goodness from an open-source granular synthesizer

A granular synthesizer — or more appropriately, a granular audio processor — is a device that chops audio samples into small “grains” that are just a few milliseconds long. It then manipulates them and rearranges them, before outputting the result. The auditory effect is interesting and appealing to experimental artists, but even low-end granular synthesizers are pricey. So, Sid Rockett used an Arduino Nano R4 to build his own open-source granular synthesizer called Arena Digitalis.

Granular synthesizers are expensive because they have to store audio samples, which takes memory, and then manipulate them in real-time, which requires processing power. Luckily, the Arduino Nano R4’s Renesas RA4M1 microcontroller has generous memory (32kB of RAM) and processing power (48MHz clock speed) at a low price. It also has analog input pins and a digital-to-analog converter (DAC).

Aside from the Nano R4, the only components required to build an Arena Digitalis are some audio jacks, potentiometers, buttons, LEDs, capacitors, and resistors. 

Those components provide input and output connections, plus the user interface. Musicians can adjust grain size and tweak tone, mix, and speed — or simply press the “random” button to make interesting sounds without any fuss. 

Because Arena Digitalis doesn’t generate audio on its own, the sound will depend entirely on the input. That can be anything from a CD to a synthesizer to an electric instrument. But no matter what you use for input, the glitching effect will add a layer of texture that you really can’t achieve in any other way and this is the most affordable way to get it.