Expression gives discrete steps on Source Audio

I was trying to implement a Wah on the Source Audio Spectrum, by sending expression messages via the MC8 to control the filter frequency on the Spectrum.

It kind of works, but the action is not smooth, and one hears discrete steps when the filter opens up. I can see also that the control LED of the Spectrum blinks repeatedly when I rock the expression pedal, and each blink corresponds to a noticeable step. Has anyone had this issue?

It could be that the spectrum is not designed to have its parameters controlled so quickly and continuously by MIDI. However, I believe there is a solution to this. Set up the Spectrum so that filter frequency is controlled by an expression pedal connected directly to it, then use CC #100 (which mimics direct exp pedal control via MIDI) to control it with your exp pedal connected to your MC8.

Thanks for the tip. Actually I tried both controlling directly the filter or the expression via CC#100, and unfortunately the same behavior occurs. Using CC#100 is also the best idea to have a single expression message defined on the MC8.

I will try reducing the range of CC values to see if that’s the quick ramping of MIDI signal that causes the problem, as you suggest, although this will limit the wah effect.