gRainbow, new free, open-source, cross-platform granular Synthesizer plugin

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gRainbow is a new free, open-source, cross-platform Synthesizer that uses pitch detection to choose candidates for granular synthesis or sampling.

Granular synthesis is one of my favorite forms because you can use it to generate very unusual sounds and beautiful, dense textures from simple sounds. You can’t have too many granular synths. And if it’s free, that’s even better.

gRainbow is a new free granular Synthesizer plugin for macOS, Linux, and Windows from Brady Boettchers. It’s open-source and not just another “more of the same” granular synth.



gRainbow is  a novel granular synth that tries to fix problems related to pitch information in classic granular synths. The developer summarizes the issues/limitations in three points:

  1. Pitch variations in the input clip can produce inharmonic tones, which isn’t always wanted. This leads users to use short single-pitch clips often, restricting the synth to a single timbre.
  2. Manual pitch matching to the input clip is often required to produce the correct notes with MIDI input, which can be difficult and repetitive.
  3. Pitch shifting is commonly done with time-stretching, which can create unwanted artifacts when shifting multiple octaves in either direction.

According to Brady Boettcher, it prefers longer, pitch-diverse audio clips that automatically produce harmonics matched for MIDI inputs. So avoid too much time-stretching by generating harmonics already near their target pitch.

How Does It Work?

Brady Boettchers’s new granular synth depends on audio material, i.e., samples that can be loaded. Once imported, a pitch detection analysis is run to segment the clip into discrete pitches over time.

Next, it finds up to 6 pitch-matched position candidates for each note, guaranteeing harmonically agreeable grains. Finally, the user customizes each note and its generators (i.e., changing parameters and candidates) to their liking and can save everything into a preset to avoid processing things again next time.

First Impression

I would have loved to tell you more about how it sounds and how easy it all works. Unfortunately, the plugin crashes on my Apple Silicon Computer in Ableton Live. I hope the developer fixes the problem. But at first sight a welcome free granular plugin with an interesting approach with a very colorful design.

gRainbow is available now as a free download from GitHub. It runs as a VST3, AU, and LV2 plugin on macOS (native Apple Silicon and Intel), Linux, and Windows.

More information here: GitHub 

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  1. Tom, it’s the macOS safeguards kicking in, because the plugin is not authorized.

    Run the following in Terminal, e.g. for VST3:
    “sudo xattr -r -d /Library/Audio/Plug-Ins/VST3/gRainbow.vst3”

    And don’t forget to tell your DAW to re-enable the plugin; I have to do this with Reason and Cubase.

  2. Hallo Tom!

    Vielen, vielen Dank für diese Seite! Toller Humor, und Mut Probleme aufzuzeigen oder eben Sachen, die nicht “passen”.
    Seit ca. 1-2Monaten kann ich keine Pics mehr sehen. Kleine Thumbnails schon umd videos auch aber sonst nichts. Hast du etwas am Layout verändert und mein 2Jahre altes iPhone ist “zu alt?! 🤣

    • Danke 🙂 Hab meinen Hoster vor 2+ Monaten zirka gewechselt. Hab bisher keine Probleme bemerkt. Mache es auf einem älteren iPhone auf mit Bilder usw. Kann dir aktuell nicht weiterhelfen sorry :S

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