Ok, so I bought this vintage guitar tube amp head by the name of Regal.

The jist of it is that after about half an hour of continuous play, the amp starts to crackle and die out. And when I turn it off for about 5 minutes after it dies, and then start it back up again, it goes back to normal for another good amount of time. Then the cycle continues.

I bought the amp with really old tubes in it, so when I first encountered the problem, my main assumption was that the tubes were causing the problems. So I replaced every tube. No luck.

Then I noticed there was no fan and the amp did start to get really hot after a while so I thought that might be the problem (it made sense because after I let the tubes cool down, the sound went back to normal). So I installed a fan to cool off the tubes. And no luck there either.

Can someone give me some advice on what to do? Has this ever happened to anyone before?

Vantage Ghost Gibson "The Paul" copy
Fender FM-100H half-stack
Regal vintage 30W class A amp head (handcrafted in Montreal)
Are you sure the ohms of the head and cab match up?

Epiphone G400
Marshall JCM 800 4211 Combo
Karmer Forum III
Schecter Stiletto Deluxe 5
Holden Graphic something bass amp? (eh it's 300 watts!)
Some sort of 1x15 cab.
That sounds like a transformer something problem.

Are the tubes still bright when it goes off?
Pain is an illusion.
Schecter Hellraiser C-1 w/ Seymour Duncan JB/Jazz Combo
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