Crack ticking only when volume down

[bboris77]

You could get a tube shield and bayonet base and install them over the 12AU7 socket. It will be kind of a PITA to do on a built amp. An alternative is to wrap the tube in copper foil, solder a wire to the foil and attach the wire to the chassis.

Problem solved. The solution was a variation on this theme - I got a 3/4 inch diameter copper coupling at a local hardware store. It fits perfectly over the preamp tube. I noticed that it took care of the interference even before I soldered a wire to it and connected it to the chassis. I tested it with a multimeter and even without the extra wire, it was grounded since the bottom of the cylinder was in direct contact with the tube socket which is grounded. It actually looks cool too. I will post a pic later.

[bboris77]

As promised, here is a photo of my improvised tube shield.

[Karl5150]

And it looks good. Even the guys who fancy the hammered copper finishes now have an solution should the same trouble arise.