Recording MPE is the easy part. Editing it is where most players get stuck. A standard MIDI take gives you notes with a start, an end and a velocity — four numbers you can nudge without much thought. An MPE take gives you all of that plus three continuous streams per note: pitch bend, pressure and slide, each running for the note's whole duration. Drag a note two beats later and those curves have to come with it. Quantise a chord and the curves need to stay aligned to the notes that produced them.
Here is a practical approach to cleaning MPE performances that keeps the playing intact.
First: Record More Than You Need
The single biggest editing mistake is trying to repair a take that was never good. Expression curves encode physical gesture, and gesture is hard to fabricate after the fact. It is almost always faster to play another take than to draw the pressure curve you wish you had played.
Record several passes, keep them all, and comp. Which brings us to the first real problem.
Comping MPE Takes
Comping across MPE takes is more fragile than comping audio, because most DAWs treat expression data as note-attached rather than track-attached. When you cut between takes mid-phrase, you can end up with a note whose pressure curve begins mid-value — the note enters at a pressure the player never applied, and the result is an audible jump.
Two rules keep this clean:
- Cut at note boundaries, not inside notes. Find a gap in the phrase, however short. If there is no gap, cut on the attack of a note rather than in its sustain.
- Check the first note of every spliced region. If the curve starts at a non-zero value, either shorten the region so the note starts fresh or manually taper the opening milliseconds.
Bitwig Studio makes this least painful because expression data lives in dedicated per-note lanes in the detail editor, so you can see exactly what you are cutting. Ableton Live shows MPE curves in the note expression view; Logic Pro exposes them through its MIDI Draw lanes; Cubase handles them in the Key Editor's note expression display.
Quantising Without Destroying Expression
Quantising MPE is safe as long as your DAW moves the expression data with the note. All four DAWs above do this correctly for their own note quantise functions. The risk is with third-party MIDI utilities and older scripts, which may quantise note events while leaving controller data in place — producing curves that no longer line up with the notes they belong to.
Two habits worth adopting:
- Quantise with strength, not 100%. MPE playing is usually rhythmically expressive by design. Snapping to the grid at full strength removes exactly the timing nuance you played the controller to get. 50–70% strength typically tightens a part without flattening it.
- Quantise before you edit curves, never after. Any manual curve work you do will need redoing if the notes move underneath it.
Repairing Common Problems
Pitch bend that does not return to zero. Very common on ribbon and surface controllers, where a finger lifts slightly off-centre. The note ends fractionally sharp or flat. Fix by editing the tail of the pitch curve back to zero over the final 50–100 ms rather than flattening the whole curve.
Pressure spikes on attack. Some controllers register a pressure transient at note-on that the player did not intend. If your synth maps pressure to filter cutoff, this reads as a click. Smooth the first few milliseconds of the pressure curve, or add a short attack ramp on the pressure destination inside the instrument instead — often the better fix, since it applies to every note automatically.
Slide drift on held chords. Fingers migrate during long chords. If slide is mapped to something audible, held pads slowly change timbre. Either flatten slide on sustained notes, or reduce the slide modulation depth in the instrument.
Know When to Stop
The temptation with visible expression lanes is to tidy every curve until it looks neat. Resist it. Curves that look messy usually sound alive. The micro-variation you would smooth out is the difference between an MPE part and a MIDI part played on an MPE controller.
A useful test: mute your edits and A/B against the raw take. If the raw take sounds better despite its flaws, you have over-edited. Keep the fixes that solve audible problems — the pitch that never resolves, the click on attack — and leave everything else alone.
A Note on Archiving
Whatever DAW you work in, export finished MPE parts as MIDI files as well as keeping the project. Expression data survives the export, and it makes a take portable if you later move projects, change instruments, or want to reuse a performance under a different sound. Given how much effort a good expressive take represents, it is worth the extra thirty seconds.