A multi-timbral instrument
A multi-timbral instrument can produce sounds on multiple channels at once. A multi-timbral instrument is often used to perform several instruments simultaneously, such as on a workstation keyboard which plays ensemble arrangements. For example, Channel 1 might be a piano, Channel 2 a guitar, Channel 3 a bass, etc.
A mono-timbral instrument
A mono-timbral instrument produces one timbre on a single channel only. Playing the Seaboard through a mono-timbral instrument means that the conflicting pitch bend and aftertouch data intended for individual notes would instead be applied equally to all notes.
Why does the Seaboard need a multi-timbral instrument?
Channel-wide messages like pitch bend or MIDI CCs are applied equally to all notes on that channel. The Seaboard uses the multiple channels of a multi-timbral instrument by assigning each new note to an individual channel so that each can have its own pitch bend and CC messages. See more details here.
Equator is a multi-timbral instrument which has been designed for the Seaboard. Instead of containing different instruments on each MIDI channel, it contains identical instruments on each channel but allows complete polyphonic expression of pitch bend and other controllers.
Is multi-timbral the same as polyphonic?
It’s easy to confuse ‘multi-timbral’ with ‘polyphonic’. Polyphonic instruments play several notes on a single channel. The Seaboard uses a multi-timbral instrument to play single notes on each channel, across multiple channels. This means that the Seaboard's polyphony is decided by the number of channels it uses, which can be set in ROLI Dashboard.