Hum / noise in 2204 build

[StingRay85]

Development a noise problem in a recent 2204 build. It does a few things that make me scratch my head.

The hum is present even when the power tubes are not conducting yet (although not so loud).

The noise is amplified by both the preamp and master volume. With the treble on 12 o clock, it's the most silent. Cutting all treble amplifies the hum greatly.

Also, the master volume pot (new ALPHA pot) is scratchy, as if there's DC on it.

I replaced all tubes by new 7025 GE to rule out any problem there. The filter caps are also new and cannot be the problem.

It's a problem that developed at a certain point, before it was quiet. So any thoughts on what it can be, and which component failure could cause this problem? The 470 pF in the treble part of the tone stack perhaps?

 

[Phoenix1]

I had a hum in a super lead build and everything was right until one guy in here said it is good and looked good and told me to just be careful and just poke around a little with something non conductive. Here is what I found, what looked like a great solder joint wasnt ! So I just heated it back up and all good !