The budget M-VAVE FM-1 keeps attracting interesting firmware. The latest is Shrub, a free wavetable synthesizer firmware from Steve Duda of Xfer Records, the creator of Serum. Synth Anatomy reported on October 24, 2026 that Shrub is in private testing, with Duda looking for experienced testers.
What Shrub is
Shrub is described as a "mini Serum" port. It is synth-only, with no groovebox features, which sets it apart from community projects such as Groove OS. According to the report it includes:
- a wavetable oscillator with 3D wavetables
- a filter section based on Serum 2, with several modes
- two ADSR envelopes and two multi-wave LFOs
- a multi-effects section with distortion, chorus, delay, OTT and reverb
- an algorithmic arpeggiator, an 8-lane motion sequencer and built-in scales
The firmware will be free to download. It is still in alpha or beta, and the report warns that flashing custom firmware can brick a device. If you try it, accept that risk and follow the developer's instructions carefully.
The MPE angle
The report does not mention MPE or other expression features, so we cannot say whether Shrub will handle per-note pitch bend, pressure or slide. We are covering it because it is part of a wider trend: small, inexpensive hardware is becoming a platform that developers can reshape, and expressive players benefit when that happens.
We looked at this shift when M-VAVE opened the unit to developers; see our piece on M-VAVE FM-1 Open and the expressive future. The key idea is that once firmware is open, someone can add features the manufacturer never planned, including multichannel MIDI handling.
Serum itself matters here. The desktop plugin has supported expression for some time, and we explained its controls in Serum 2 MPE controls. A hardware descendant could, in principle, borrow that thinking. That is speculation, and nothing in the report promises it.
What a mini wavetable synth is good for
Even without MPE, a wavetable engine with motion sequencing is useful on stage. You can pair it with a controller that sends a single channel of aftertouch, or use it as a drone and texture layer under a main expressive instrument. If you are building a small rig, our touring rig guide covers how to combine sound sources.
Questions worth asking Duda
Testers and early users can help shape the project by requesting a few things: polyphonic voice handling that is aware of MIDI channels, assignable pressure and slide sources in the modulation setup, and a documented pitch bend range. These are the three ingredients an MPE controller needs to feel natural.
How to follow along
Keep an eye on Xfer Records and the community forums for the release. Because Shrub is not yet public, details may change before launch.
Key takeaways: Shrub is a free, upcoming wavetable firmware for the M-VAVE FM-1 from Serum's creator. It is in private testing, and MPE support has not been mentioned, so treat it as a promising sound source rather than an expressive instrument for now.