GForce Oberheim Matrix 12 has two distinct global modes, called Single and Multi. The mode Matrix 12 is in determines much of its operation and the features available.
Switch between these modes using the large Mode button in the centre of the upper panel.

In single mode, Matrix 12 operates like a fairly normal 12 voice polyphonic synthesiser. A single control set in the voice panel serves all 12 voices; and while the analogue oscillators and filters show slight differences, each voice sounds effectively identical.
In the upper panel of Single mode you’ll find a screen to set the number of voices Matrix 12 uses from 1 to 12.

Voices in Matrix 12 single mode rotate. Always using the next available for voice for each new note received.
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There is no traditional mono or mono legato mode in Matrix 12, set voices to 1 for this. Retriggering (or not) is handled in the envelope/LFO modules.
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Enable Unison and all enabled voices will play at once.
Detune and Spread are available in both modes, however they are more important in single mode as one of the only ways to introduce deliberate variations between the voices.
More: Master Section

In multi mode, Matrix 12 becomes twelve independent semi-modular mono synthesisers. Or two 6 voices ones, or 4 three voice… you get the idea.
Multi mode has a range of additional features that we’ll link to here: