The Raspberry Rainbow Synth is a DIY synthesizer that uses an onboard Raspberry Pi 4 microcomputer, Python 3, and Cycling 74’s RNBO software along with various potentiometers, buttons, and an LCD. The synth uses RNBO patches as the sound source and provides a menu on startup for a player to select which patch to load for performance. This is an upgraded version of an original synth I built in 2015 using a Raspberry Pi 2 computer and Pure Data.

I like that this is a relatively inexpensive instrument that makes us of open source technology and software. It is simple in its design and purpose. The lack of fancy controls and the inherent limitations that come from using a microcomputer are perks to me as a computer musician / improviser. The instrument’s limitations posit a sound world that is unique and different from a world using my MacBook Pro and a more CPU hungry sound patch. I like when there are limitations and fewer possibilities in scale considering the almost limitless sound possibilities available in most commercial software.

All of the components inside the box were soldered by hand and the circuits to transduce the knobs and buttons are very simple. Even so, the inside of the box is still a bit of a wired mess. If I ever find the time to continue down what I call the Pi Wormhole (TM) my thought is to print simple PCBs and make a basic kit. We’ll see . . .

Live performance of Atari Punk Pi-Synth Improvisation. In this performance the Rainbow Pi Synth processes the live input of a modified Atari Punk Console synthesizer that I built.

Here is a short improvisation using the synth and a recording of a harpsichord:

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Below is a more technical overview of the instrument that I prepared for the MoxSonic Music Festival.

Below is a basic overview of using RNBO and a brief demo of a RNBO granulator patch.

Pure Data Videos (older)

Photos