Not every MPE milestone comes from a big brand. Idle Foundry's CA-72, a free and open-source synthesizer, has reached version 0.3.0 and added MPE support, according to its KVR Audio product page. For players who want to try expressive controllers without buying a new plugin, it is an easy download.
A synth built to run on any system
CA-72 is licensed under GPL 3 or later, with no copy protection, and the source code is available on GitHub. Formats cover VST3, CLAP and Audio Unit (macOS), plus a standalone application. Platform support is unusually broad:
- macOS 11 or later, on Apple Silicon or Intel
- Windows 10 or 11, 64-bit
- Linux x86-64 (Ubuntu 22.04, Debian 12, Fedora 36 or later)
Linux support is the notable part. Expressive controllers are popular with hardware-minded players, and a CLAP-ready synth that runs on Linux fits well with open-source DAW setups. You can find the developer at idlefoundry.com.
What is new in 0.3.0
Beyond MPE, the 0.3.0 release adds several features that suit expressive playing:
- Arpeggiator for pattern-based performance
- Four LFOs and six macros for flexible modulation routing
- Velocity modulation, newly added
- Continuous oscillator waveforms with shape modulation
- Monophonic mode or 2 to 10 voices of polyphony
Then there are the more unusual controls. ENTROPY introduces component variation and drift, so voices never sound identical, a trait that makes chords feel more organic. SPREAD handles stereo voice placement. A FEEDBACK control and external audio input round out the sound-design toolkit, and there are 42 factory presets to start from, plus user preset storage and a resizable interface.
Why MPE and a drifting oscillator pair well
Per-note expression exposes everything an instrument does badly. A static, perfectly tuned voice sounds sterile once each finger can bend, press and slide separately. A design that already includes per-voice variation, like CA-72's ENTROPY, tends to reward that treatment, because every note starts from a slightly different place and then moves under your hand.
The 2 to 10 voice limit is also a practical advantage for MPE. Controllers usually send each note on its own MIDI channel, so a synth that lets you cap the voice count helps you match the polyphony your controller can actually deliver, and keeps CPU use predictable on older machines.
Getting started with an MPE controller
If you own a controller such as the LinnStrument, the Expressive E Osmose or the Exquis, a quick test routine helps:
- Load a preset in your DAW and make sure the track receives MPE (many hosts have a dedicated toggle).
- Set your controller's pitch bend range to match the synth's. Mismatched ranges are the most common reason notes sound out of tune.
- Play a held chord and bend a single note. If the others stay put, per-note pitch is working.
- Assign pressure or slide to a macro and listen for independent movement per voice.
Keep in mind that CA-72 is still a 0.x release, so expect rough edges and check the project page for notes on exactly which MPE dimensions are mapped. Free tools like this are a low-risk way to learn what each gesture does before you commit to a larger investment.
The bigger picture
Free, open-source synths supporting MPE lower the barrier for newcomers, students and tinkerers. As the ecosystem grows, a healthy mix of premium and community-built instruments gives expressive players more places to explore.
Sources: KVR Audio: CA-72, Idle Foundry, CA-72 on GitHub.