It's a JetCity 50W head. When the amp is turned on and I strum my guitar.... It makes this crackling, terrible noise for 45 minutes, then all of the sudden it starts working fine. Once it starts working, it sounds great and I can play it for hours without any issue.

I've experimented with all of the following variables:
- I've tried replacing all the tubes
- Tried multiple guitars, multiple cabinets, multiple instrument/speaker cables
- Tried taking effects out of the effects loop, problem still persists
- Problem is consistent no matter what kind of power source I'm plugged in to (Direct in to wall, extension cord, surge protector, ETC)

Here's the clip....

I've read that a lot of JetCity amps have bad Bias pots.... is this noise consistent with a bad bias pot?