Volume fluctuations on tube amp

[nateman76]

Hello,
I had built a 50 watt tube amp from Metro Amps about 5 years ago. I really hadn't started to use it till recently. When I started to play through it recently I noticed that after I warm the amp up for about 15 min, the volume is real low. I noticed this as I had turned the volume to 2 and played through it for about 20 min then all of the sudden the volume spiked dramaticlly and was twice as loud. After a bit the volume would go back down then up again. After the volume would stop fluctuating I turned it to standby and when I went to play through it again the same thing would happen. The amp is a kit modeled after the Marshall Plexi amps. It is %0 Watts, I have two Mesa EL34's and two 12 ax7's in pre. I replaced the tubes and re-set the bias already but the problem is still there. I suspect I either need to clean the tube sockets, replace them or try to find out if it is another component that is causing the problem. Any suggestions? You can get as technical as needed as I do have an Electronics Degree.

[Reeltarded]

Does the sound of the amp change or only the volume?

You have a loose joint in your signal path. When it heats up and expands it sometimes connects and sometimes not. You need to chopstick it when the amp is warm. Poke around in the signal path with a nonconductive pointy thing.

Plastic is not always nonconductive!