Using Quad Cortex to control Voodoo Labs GCX

Hey, all!

I’ve racked my brain (over the last week) programming the Quad cortex (via CC message) to communicate with a Voodoo Labs GCX.

  • I’ve tried connecting both QC midi ports to the GCX ‘midi out’ (as recommended by Voodoo Labs) to no avail.
  • I’ve tried multiple midi cables both store-bought and custom-made (myself)
  • The Voodoo Labs GCX power cycles then goes black

Any insight? Thank you! :slight_smile:

Hi @JD13 and welcome to the community. If you are unable to get anyone to respond that uses the VL GCX midi controller, give NDSP a shout at and they will get you sorted quickly.


I used to have a GCX way back so can try to help.

I’m a bit confused by your first statement “I’ve tried connecting both QC midi ports to the GCX ‘midi out’”

Maybe I’m not understanding your comment but the MIDI OUT socket on the GCX is an out/thru which replicates anything coming from the GCX Pedal In/Midi in socket on the GCX. If you are trying to control the GCX from the QC then you only need the following connection.

QC Midi Out socket > GCX Pedal In socket

Obviously, make sure the midi cable is DIS (disconnected) on the required PINS 1 and 3 (as per the GCX manual). Completely remove any other connections from QC midi IN and GCX midi out sockets.

If not already done, check the QC is set to send on Channel 16.

Then, check the following tests sending CC messages 80 - 87 (change the midi channels as required for the respective devices. Also, test CC’s 79 and 88):

  • QC to other midi device (that isn’t the GCX) that can respond to CC messages

  • 2 devices that aren’t the QC or GCX

  • Connect QC Midi Out to an audio interface (if owned) that has midi input and monitor midi messages sent (via DAW or download ‘midi monitor’ app on PC/Mac and check what is sending ).

If all is well/expected then you can be fairly confident that the cable is good and also that the QC is sending out the midi CC messages correctly. This would, of course point to the GCX as being the issue.

You could then test another controller type device or try sending messages out of an audio interface (via Daw) to the GCX on Channel 16 and see if results are the same.

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