[sdiy] MIDI, note off or note on with zero velocity?

[Colin f]

> I don't think you can generalise from an obvious bug in a 
> synth that's nearly thirty years old now.

The MIDI spec doesn't define what a synth should do with multiple note ons.
It says, "it is up to the receiver as to whether the same voice or another
voice will be sounded, or if the messages will be ignored".
It says nothing at all about the handling of note-offs.
There are other synths that will misbehave with stacked note ons, just none
that I own.
I implemented code to prevent stacking of note ons after reports of hanging
notes from users of my sequencers.
IIRC there were issues on the Access Virus, or some other modern synth, but
problems are not uncommon.
 
> Musically, it's pretty damn useful to have multiple voices 
> playing an identical line on the same channel. E.g. it's an 
> easy way to fake a unison mode on synths that don't have one.

If you want to control voice allocation directly, you can use omni off, mono
mode (4).
That is exactly what it's meant for.
It has the added advantage of no confusion about which note off goes with
which note on, and unambiguous targetting of other MIDI messages which link
to specific note messages, such as poly aftertouch and portamento control
(PTC).
 
Cheers,
Colin f