LinnStrument Support Page

What is MPE?

MPE stands for "Multidimensional Polyphonic Expression" and is a new MIDI standard created by us, ROLI, Apple, Moog, Haken Audio, Bitwig and others for communicating over MIDI between MPE controllers (like LinnStrument, Roli Seaboard, Continuum, SoundPlane or Eigenharp) and MPE sound generators (like these).

The principal reason for MPE is to get around a limitation of MIDI: Pitch Bend and Control Change messages must apply to all notes on the channel. This prevents polyphonic pitch bends and polyphonic Y-axis control (which uses Control Change messages) over a single MIDI channel. MPE solves this problem by sending each note's messages on a separate MIDI channel, rotating through a defined block of channels. Here's a brief summary of MPE:

Each note's messages are sent on a unique MIDI channel, rotating through a defined contiguous block of channels called Per-Note channels. The per-note messages are limited to Note On, Note Off, Channel Pressure (for finger pressure), Pitch Bend (for X-axis movement) and CC74 (for Y-axis movement).  All other messages (like Program Change, CC7/volume, CC64/Sustain, etc.) apply to all voices and are sent over a separate "Common" channel, though some MPE synths do not implement a Common channel, instead receiving these Common messages redundantly over the Per-Note channels.

In LinnStrument, MPE is called "Channel Per Note" mode, and the Common channel is called the "Main" channel.

Roger Linn Design  •  Berkeley, CA, USA

Roger Linn Design  •  Berkeley, CA, USA