The last few months have been unusually good for MPE players watching the plugin market. Ultra 1.1 added full MPE to its five-engine flagship in late August. DiscoDSP brought per-note expression to both Vertigo and Corona. Smaller developers keep shipping updates with "MPE" in the changelog.
The trouble is that "MPE support" is not a certification. There is no compliance badge, no test suite a developer must pass, and no agreed minimum. The phrase in a changelog can mean anything from a complete per-note modulation architecture to "we no longer collapse incoming channels". Both are technically improvements. Only one of them will hold up in a performance.
Here is how to work out which one you have bought — before you build a set around it.
Step 1: Check the Pitch Bend Range
Load the plugin, engage MPE mode, and look for a per-note pitch bend range setting. The MPE specification uses ±48 semitones as the default for member channels, and virtually every controller ships configured that way.
If the plugin offers no separate per-note bend range, or applies your global ±2 setting to member channels, glides will be wildly out of proportion — a small finger movement will produce a huge interval, or none at all. A plugin that cannot set member-channel bend range independently is not properly MPE-aware, whatever the changelog says.
Step 2: Find Out Where the Three Dimensions Land
MPE gives you three continuous per-note streams: pitch bend (slide left and right), channel pressure (press), and CC74 (slide up and down, usually called timbre or Y). The question is what each one is wired to.
Play a sustained note and move each dimension in isolation. Then ask:
- Does pressure reach anything other than volume? Hard-wiring pressure to amplitude alone is the most common shortcut. It sounds responsive for about a minute.
- Is CC74 received at all? Many plugins implement pitch and pressure and quietly drop the timbre axis.
- Can you route these three to arbitrary destinations in the modulation matrix, per note, or are they fixed?
The last point is the real dividing line. A synth where pressure and timbre appear as first-class modulation sources — assignable to filter cutoff, oscillator morph, FM index, resonator damping — is a synth you can design MPE patches in. A synth where they are hard-wired to two parameters chosen by the developer is a synth you can only play someone else's MPE patches in.
Step 3: Test Voice Behaviour Under Load
Play a five-note chord, hold it, and add a sixth note while bending the first. Two failure modes show up here.
Voice stealing that ignores channel assignment will cut a held note when the new one arrives, breaking the per-channel mapping and leaving a stuck bend behind. Channel rotation errors appear when the plugin reassigns a member channel that is still sounding — you will hear one note suddenly inherit another note's expression.
Both are much more likely in plugins where MPE was retrofitted onto a voice allocator that was never designed for it. Ten seconds of chord work will tell you more than any spec sheet.
Step 4: Check Release Velocity and Note-Off
Release velocity is part of expressive playing on controllers that measure it, and it is routinely ignored. Lift a note slowly, then sharply, and listen for any difference. Plenty of otherwise capable synths treat every note-off identically.
Step 5: Look at the Factory Presets
This is the fastest proxy for developer commitment. If an update adds MPE but ships no MPE-specific presets, the existing patch library was almost certainly not revisited, and you will be doing the sound design yourself. Conversely, a dedicated MPE bank is a strong signal that someone at the company actually played the thing with a controller.
Step 6: Confirm Your DAW Is Not the Problem
If a plugin behaves oddly, rule out the host before blaming the developer. MPE has to be enabled explicitly per-track or per-plugin in most DAWs, and the settings live in different places in Bitwig, Ableton Live, Logic Pro and Cubase. A plugin that works standalone and fails in a session is usually a host configuration issue.
The Short Version
Real MPE support means: an independent per-note bend range, all three dimensions received, all three freely routable, a voice allocator that respects channel assignment, and preferably presets that use it. Anything less is per-note pitch bend with good marketing.
None of this requires special tools — a controller, a blank project and ten minutes will answer every question above. Run the test during a trial period rather than after.