Re: [AH] Moog One selloff!: Deckards Dream, Midiboard, Digitakt, Digitone!

From Brian Willoughby
Sent Mon, Oct 8th 2018, 22:28

On Oct 8, 2018, at 2:50 PM, Scott Fox <xxxxxxxxx@xxxxx.xxx> wrote:
> Mode 4 allows you to pitchbend just one note of, say, 5 notes played? =
A stable low chord and pitch vibrato on a single high note without =
affecting the others? It's my understanding that mode 4 still shares a =
common pitchbend. If I'm wrong, please correct me.=20
>=20
> This is something I use constantly when working with MPE.

MIDI has 16 channels. That means you have 16 Pitch Bend messages. Things =
must be coordinated between the controller and the synth. If the =
controller assigns a different channel to each note, which is what both =
Mode 4 and MPE do, then you=E2=80=99ll have a unique Pitch Bend for each =
note.

The message that puts a receiver into Mode 4 is itself on a channel =
number, but that merely sets the Base Channel. Mode 4 can either specify =
the number of voices, up to 16, or it can specify =E2=80=9C0=E2=80=9D to =
ask for all of the voices of the receiver. Starting at the Base Channel, =
each next channel controls the next voice, and changes (including bend) =
for each note should have a different channel.

There is a Global Controller channel, which is one below the Mode 4 Base =
channel, that is used for controls that affect all notes. If you have =
one Pitch Bend wheel on a physical polyphonic expression controller, =
it=E2=80=99s most likely that moving the one bend wheel will be sent on =
the Global Controller channel and affect all notes, since there=E2=80=99s =
no way for the controller to know which individual note you intended it =
for. However, if you assign pitch to some movement of an individual key =
- such as pressure or X or Y position - then this control change message =
should be sent on the channel that is active for that note.

MPE is almost exactly the same, except that the Master Channel is the =
first channel, rather than one below that. In fact, MPE is limited to 15 =
polyphonic channels, since control changes on the 1st channel are =
defined as affecting all notes on all channels. Depending upon how an =
MPE controller is set up, it can still have a single Pitch Bend wheel =
that affects all notes in a chord if the Pitch Bend message is sent on =
the Master Channel.

So, yes, MIDI Mode 4 definitely supports a unique pitch bend for each =
note.

There=E2=80=99s basically no difference between Mode 4 and MPE here, =
except for the numbering of the Global versus Master channels. Actually, =
MPE is a little more explicit in pointing out the Master Channel, which =
unfortunately reduces it to support only 15 voices, where Mode 4 allows =
the Global Controller channel as a vague option, so you don=E2=80=99t =
really know whether you have 16 voices and no Global Controls, or 15 =
voices with Global Control.

I get the impression that since MIDI Mode 4 was created in the days when =
5, 6, or 8 voices was about the most we ever expected, they didn=E2=80=99t=
 really think about the importance of stating with certainty whether the =
Global Controller channel took away a voice. Strangely, given that MPE =
is supposed to improve MIDI by being much more explicit about things, I =
still get the impression that people don=E2=80=99t actually realize that =
MPE is limited to 15 Member Channels. In other words, with a 16-voice =
Moog One, you can=E2=80=99t actually have 16 independent pitch bends. =
You can have 15, but not 16. In contrast, Mode 4 can do 16, but not =
unless you set up both the controller and the synth to handle it. MPE =
simplifies this by forcing the limit of 15. Of course, MPE still manages =
to be vague by allowing an Upper Zone that reduces the limit of 15 to =
even lower channel counts.

Brian Willoughby