Sending MIDI CC to multiple midi Channel
A single CC message applies to a single channel. If you want to affect multiple channels, you have to send multiple messages:



usbMIDI.sendControlChange(controllerAx, nx, 0);
usbMIDI.sendControlChange(controllerAx, nx, 1);
usbMIDI.sendControlChange(controllerAx, nx, 2);
usbMIDI.sendControlChange(controllerAx, nx, 3);
...


And this should of course be done in a loop:

for (int c = 0; c &lt; 16; c++)
    if (c != 10)
        usbMIDI.sendControlChange(controllerAx, nx, c);