User's Manual

8. CONTROLLING EXTERNAL SYNTHS
8.1. Control Mode
In Chord mode, the KeyStep 37 knobs send note values and triggers over MIDI to external
synths. The Chord button has a second function that, when activated, turns the knobs into
CC controllers. In this mode, they can transmit control change messages to external devices
that are connected to the MIDI Out port (5-pin DIN). The same data will be sent to your
computer via the USB port.
Each of the four knobs can control a parameter on an external device. But there's more: you
can switch between four banks and each bank can hold four values. Changing banks will
enable you to control another group of four external parameters.
On startup, the chord button lights up in a dimmed orange colour. To activate CC mode,
press the Chord button; the button will turn white to confirm that you've indeed selected CC
mode. Hold Shift and press the Chord button repeatedly to cycle through the four banks.
The changing colours will indicate what bank you have selected. The Chord button acts as
a toggle, it will switch between chord mode and the last selected CC bank.
8.1.1. What are CC# messages?
When you draw notes in the MIDI editor of your DAW, you create MIDI data. With each
note you add, you create a note-on message, a note-off message and a velocity value, all
associated with a particular MIDI note number. Note number and velocity values (like most
values in MIDI) are in the range 0-127. The velocity value imitates how fast a key is struck on
a MIDI keyboard. When you create a note with a high-velocity value (> 100) in your DAW,
the associated note will sound fairly loud on the synth you send it to.
When you connect an external synth such as the Arturia MatrixBrute or MicroFreak to your
DAW and press 'play', the DAW starts sending a stream of messages to the synth over MIDI.
The MatrixBrute or MicroFreak interpret these messages and play your DAW sequence the
way you intended it to sound.
In addition to note-on and note-off messages, there's another kind of MIDI data that allows
you to control parameters on external synths, modular systems and virtual instruments
loaded in DAW tracks. These Control Change (CC) messages are different from, and
independent of, the note-related MIDI messages. They are referred to as CC# messages:
strings of numerical data that are specifically designed to control parameters on an external
MIDI-compatible hardware or software device; for example, a hardware synth, a Eurorack
modular system or a software modular system such as VCV Rack.
A CC message consists of a Controller number (CC#) and a value. The controller number
determines what parameter on the external synth must be controlled, the value determines
the amount of control that must be applied.
Arturia - User Manual KeyStep 37 - Controlling external synths 66