(Modulate This) Contollerism MIDI Sound Design

CME Xkey Tip: Latching Sustain for Drones and Arps

I use my Xkey 25 Air pretty much every day in the studio. No matter what state my studio wiring is in, I can just turn this bad boy on and I’ve got velocity, pressure, mod wheel, pitch bend and octave shifts at my fingertips.

Because it’s so compact with no knobs to snap off – I also throw it in my pack for experimental ensemble sessions and performance where I don’t want to bring a lot of gear. In these situations I don’t want to have use a finger to hold the sustain button for drones and/or holding notes for synths that don’t support arp latch (U-He synths for example).

The good news is you can configure the button to toggle the sustain pedal on and off. Open the Xkey editor then:


  1. Press “Read Selected from Xkey” button in the interface to load the current settings of the Xkey into the editor.
  2. Click the sustain button in the editor’s interface
  3. Change mode from “Push” to “Switch”
  4. Make sure the CC Number is set to “CC64: Hold Pedal On/Off”
  5. Press the “Save modified to Xkey” to save changes back to Xkey

That’s it! Now when you press the sustain button, it will toggle on as if you were holding the button down (or your foot on a sustain pedal). Press it again, and the sustain releases.

Drone on!

Mark Mosher
Sound Designer and Teacher of Synth Tech & Technique

3 replies on “CME Xkey Tip: Latching Sustain for Drones and Arps”

Additional settings in the Xkey app Mod Wheel and Pitch when they are in the default “control” mode are are below. You can completely change their function as well (ex. PW can be program change).

Mod Wheel:
Mod Wheel by default snaps back to 0 by default
– Mode: Push (default), switch
– Initial value as either Min or Max (so you could snap to 127)
– And you can adjust the velocity curve of the push

Pitch Wheel:
Snaps to 64
– Pitch +
– Pitch –
I’m assuming to invert the pitch.

Note, I’m working on a Max for Live Midi device with Mod, Pitch, Breath, Aftertouch, Sustain Latch, and 4 x/y so I can latch from Xkey, then manipulate these params from a generic MIDI controller, Novation Launch control, or mouse. Handy for sound design work when you don’t have a controller plugged in.


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