I am having trouble with a number of volume pedals, ranging from el cheapos to Ernie Ball and Boss high quality units. The problem is, I plug the keyboard output into the volume pedal, then volume pedal output to powered speaker. All is good, except as the volume pedal is moved (up or down) there is static noise coming through the speaker. Once it is set and not moved, there is no noise. I thought it was the cheap volume pedal I was using, so I bought a second-hand Ernie Ball unit. Same result. Then I bought a new Boss unit. Same issue. I have searched forums and hear mention of pots that need cleaning, but can this possibly be the issue with so many pedals and even a brand new one? Please help! Thanks.