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This page is read from MIDI Instrument Definitions, a Python library used in the author's other projects, in which every number is traced to a document its maker published. Its source is on GitHub.

Akai Professional MPC Key 37 MIDI implementation

The MIDI implementation of the Akai Professional MPC Key 37: what it answers to, and the 3 controls it offers, on firmware 3.9.1.

At a glance

Firmware
This page describes firmware 3.9.1.
MIDI channel
Any one of 1 to 16.
Voices
Not recorded.
Note range
Not recorded.
Velocity
Sent and received.
Aftertouch
Channel pressure and polyphonic, each answered. It sends aftertouch too.
Pitch bend
How far it bends is not recorded, and the range can be changed.
Program change
Received and sent.
MIDI clock
Sent and received.
Start and stop
Not recorded.
Control change
Assigned by the player, apart from the 3 controls below.
NRPN
Not recorded.
System exclusive
Not recorded.

Controls

In the order the definition gives them, by group. Under each control is the name a program calls it by, once pymidiinstrumentdefs.load("akai/mpc_key_37") has loaded them.

Wheels

Control CC Values
Mod Wheel
modulation		 1 0-127
Sent, never received; The factory's number, which the player can change

Without a group

Control CC Values
Mod Wheel
modulation_wheel		 1 0-127
Received, never sent
Expression
expression		 11 0-127
Received, never sent

Where these facts come from

Source documents

How they were read

THREE DOCUMENTS, ALL THREE SHARED WITH TWO OTHER DEFINITIONS, AND NONE OF THEM IS ABOUT THIS MACHINE. The MPC Standalone OS user guide describes an operating system running on fourteen machines; the two sets of release notes name all fourteen in their compatibility lines. So the work here was scoping rather than transcription: deciding which of 530 sheets' statements are about an MPC Key 37.

akai/mpc_live reads the same guide and sets out how it tells its machines apart - in five places, of which only one can be searched for. That account is not repeated here, and a reader of this definition should read it, because it is the reason to doubt any statement in this document that does not name a machine.

WHAT IS NEW HERE IS THE KEYBED. Two sheets, 102 and 103, are headed Keyboard Control and open by naming the three machines they cover, this one among them. They give the aftertouch, the note-on velocity, the keyboard's own MIDI channel, the pitch wheel's and modulation wheel's assignments, and a local-off setting - none of which the two definitions before this one had any reason to read, because neither of their machines has keys.

AND THE KEYBED'S SHEETS PUBLISH ONE CONTROLLER NUMBER, the wheel's factory 1. The two the instrument answers to, 1 and 11, come from the pages the MPC Live reads: the arpeggiator's modifiers "enable Expression messages (MIDI CC #11) from external MIDI controllers to modify the arpeggiator" (guide p. 85), and the same for "Modulation messages (MIDI CC #1) from external MIDI controllers" (guide p. 85). See the comment above the definition.

WHAT THE PROGRAM CHANGE FIELD CANNOT SEND. A track's outgoing program change takes "a value from 1-127" (guide p. 54), so this machine cannot send one of the 128 numbers a program change can carry - which is a fact about the field rather than about the format, and is recorded here because nothing below holds it.

NOT RECORDED: the note range and the polyphony, neither given for this machine anywhere in the guide or its specification table. NRPN and system exclusive, neither word anywhere in 530 sheets or in either set of release notes - which is the silence the MPC Live's definition established and this one inherits rather than re-proving. And program_change.presets, for the reason that definition gives: what a program change selects here is a sequence or a track rather than a preset.