Voodoo Lab

Hi
I use the GCP/GCX to control a mesa triple rectifier head, 3 pedals and 2 line6 racks (midi AND audio). I'd like to add a sequencer live, that would send a clic track to the drummer and arrangements tracks to the PA.
I'd like to know how I could start/stop a sequencer with the Ground Control Pro + GCX. My sequencer is hosted by a Macbook pro. I've read the manual through and through but this part is not very clear. Does the GCP send a Jack signal via a GCX loop to start the sequencer or is it via a midi channel?
Could you help me there?

Sequencer Start/Stop is a MIDI command sent by the Ground Control Pro from one of the Instant Access buttons. Connect your sequencer to the rig via MIDI, no GCX loops will be required for this.

Thanks for your answer.
Any midi channel or midi devices? Cause I already tried that.

In this case your computer is the MIDI device so you will need a MIDI interface if you do not already have one.