Mutable Instruments' Beads, the granular processor that was Emilie Gillet's last module before she left the Eurorack market in December 2022, has been released as open source. According to Synth Anatomy's report, both the hardware design and the firmware are now public under the MIT license, and the code lives in the pichenettes/eurorack repository on GitHub.
Beads is not an MPE device, and nothing in the announcement claims otherwise. But for anyone interested in expressive music technology, the release is worth a closer look.
What Beads is
Beads is a live granular processor for incoming stereo audio, positioned as a reinvention of the much-loved Clouds module. It can behave as a delay or reverb, as a granular processor, or as a granular synth working on eight internal wavetable banks. In other words, it turns sound into a malleable texture that you shape in real time.
That "shape it in real time" idea is exactly where expressive performance lives. Whether the gesture comes from a knob, a CV signal, or a pressure-sensitive surface, granular engines reward continuous, nuanced control: grain size, density, position and pitch all respond beautifully to a moving hand.
Why open source matters for expressive tools
Mutable Instruments modules have a long history of being studied, forked and reimplemented. Much of what the community knows about compact digital synthesis and effects was learned by reading Gillet's code. Having Beads in the same public repository means:
- Learning material: developers can see how a modern granular engine is structured, from buffer handling to grain scheduling.
- Preservation: the design no longer depends on a single company or person to stay alive.
- Adaptation: developers can port the algorithms to plugins, standalone apps or other hardware, subject to the MIT license terms.
That third point is where the MPE world could benefit. The expressive community often finds itself with fantastic controllers and a shortage of engines that make full use of per-note slide, pressure and pitch. Open, well-documented DSP is a starting point for people who want to build instruments around per-voice expression rather than bolt it on afterwards.
What it does not tell us
It is important to stay grounded. The announcement does not mention MPE, polyphonic expression, or any expressive controller support, so there is no indication that Beads responds to MPE data in its current form. It is a Eurorack module, driven by whatever CV and audio you patch into it.
If you want to bring a pressure-sensitive controller into a modular setup, you will typically need a MIDI-to-CV interface that can handle multiple channels or per-note data. Readers exploring that route may want to look at Polyend's MIDI-to-CV tools, and to check each product's documentation for exactly how it treats MPE channels.
A reminder about licensing
The MIT license is permissive: it allows reuse and modification, including in commercial projects, provided the original copyright and license notice are kept. If you plan to build on the code, read the license text and the repository documentation yourself, and credit the original author appropriately.
Why this is good news
Even without MPE in the picture, Beads becoming open source is a positive signal for the broader ecosystem of expressive instruments. Open code lowers the barrier for small developers, students and hobbyists to experiment with ideas like per-grain control, spectral processing or gesture-driven textures. Some of those experiments will end up in plugins and hardware that are designed for MPE from day one.
For now, if you are a Eurorack user, Beads remains a rewarding module to explore. And if you are a developer, the repository is an excellent place to spend an evening.
Key takeaways: Beads is now open source (MIT), it is a granular processor and synth for Eurorack, it is not announced as MPE-capable, and its real value for the expressive community is as a learning resource and a foundation for future instruments.
Sources: Synth Anatomy, GitHub repository.