Unison mode

[probonopd]

Looks like, e.g., the Korg opsix has a Unison mode, where you set up one voice, and then just enable Unison with three parameters:

• How many voices to use (2...8), --> We would want 1/off to 4 voices

• Spread (how much Stereo Pan to use), --> We would want from no Spread to hard left/hard right, but modified by (by adding) the per-TG Pan (clamped to hard left/hard right)

• Detune (how large the overall range for is for Detune across all voices) --> We would want it from 0 (no detune) to maximum = 1 semitone down/1 semitone up (based on the detune range of the Dexed plugin; to be verified if this matches the DX7 detune range)

• See the Unison, Detune, Spread sections in the Korg opsix manual.

WIth more powerful Raspberry Pis, maybe we can have more than just 8 voices in total? 8 TGs wich can have Unison would theoretically give us up to 64...

[probonopd]

"Additional Parameters (ACED Format)" in the Yamaha DX7 II D Supplement Booklet specifies the parameter the DXII uses for Unison, especially PMOD (unison off/on) and UDTN (unison detune depth). No way to set the number of unison voices and the amount of stereo panning?

This is how it worked in in the DX II D:

Source: Yamaha DX7II Owner's Manual page 60

Maybe this is too rigid for today's use?

[probonopd]

fwiw, the Korg opsix native VSTi also implements this as described in the original post. Makes a big difference for many sounds!

[probonopd]

I can think of two ways of achieving the outcome described in the original post.

Way 1: Per TG, have one or multiple additional Synth_Dexed instances for the unison effect. Each of the Synth_Dexed instances would run slightly detuned, and the stereo spread would be applied outside of Synth_Dexed.
Pros: Synth_Dexed stays unchanged.
Cons: We need many Synth_Dexed instances (e.g., 4 instances instead of 1 per TG if that TG should have 4 voices detune).
PoC: #892

Way 2: Per TG, have one instance of Synth_Dexed, which gets changed to play each note multiple times, slightly detuned and stereo panned. This would mean that Synth_Dexed would need to become Stereo.
Pros: We don't need more Synth_Dexed instances.
Cons: Every instance would play more notes in parallel, and would have to be in Stereo. Changes in Synth_Dexed needed.
PoC: #901

Thoughts?