PF500 Clicking noise
 

Just hooked up my 2nd 115HE cab to my PF500. Sounds awesome, but seems when I turn up the highs on my guitar I hear a very low steady clicking noise. As soon as I back off the treble a liitle on the guitar, it's gone. This happens with my both basses. Less with my Fodera and more with my Fender jazz. Anyone ever experience this with the PF500? Weird, doesn't happen with the treble turned up on the amp?

Watch near the pickup? Cell phone near amp or pickup? I've run across both causes before.