When changing the voices on the cp 4, connected to a fc7 foot pedal there is a sudden significant jump in volume until I move the fc7( increase or decrease the volume). Any fixes?
The CP4 Stage will recall the Stored Volume for each Performance. This can differ from your pedal position. That is why this is happening. The position of your pedal is not applied to the next Program until you activate (move) it. The volume that is stored in the program is automatically recalled.
If you want a "live" Volume pedal, you'll need to get one that is applied to the main Left/Right outputs (like an organ or guitar player would use). You'll want to get a stereo volume pedal through which you run the entire output of the instrument.