Pulsing Amp Noise

[canadiandream12]

Ok, I have a Peavey Special 212 and a Peavey Vypyr, both solid state. I run an A B pedal through both to switch between amps because I like to use the 212 for rythem and the vypyr for leads. When the I'm using the the 212 and the vypyr is idle on a clean channel, there is no hum. But when the vypyr is idle on a distortion channel while I'm using the 212 there is a pulsing hum that is coming from the vypyr this is really annoying...any help please?

 

[ranjam]

I could be wrong (and I often am), but I'll guess that the input to the Special is left 'open' when using the Vypyr. You may have to redesign your A/B box with at least a DPDT footswitch. I don't know your A/B box, but if it is just a SPDT with no LED's, use a DPDT and have the other input 'grounded'. Your problem should go away. If you have a DPDT footswitch and some LED indicator switching, use a 3PDT switch. Wait, I may be smart enough to know how a DPDT switch could work, activate LED's, and ground the input to the amp you aren't playing through. Or not.