Why does my gain tone get ratty after the tubes get hot?

[JimEff]

Anyone else experience this on their tube amps?

I set my Master and Drive just right, then after playing for a while (at gig volumes) the overdrive tone starts getting ratty and fizzy. It's not ridiculously bad but it's certainly noticeable to my ear.

It's happened on more than one amp so I don't think it's an amp problem.

[jojo]

No, usually tone gets better the hotter they get.

[3th3r]

You don't say what amp it is, or what you have tried to diagnose the problem, such as changing tubes or checking voltages, but one possible cause is overheating that can cause solder joints or PCB tracks to lose proper connectivity.

Or maybe it's your ears that get tired after a while (not kidding).

[JimEff]

...Or maybe it's your ears that get tired after a while (not kidding).

Never heard of that but I'm not disputing it...

I figured the brand names of the amps would be irrelevant. Mostly Marshall clones...1974X, JTM45...

Previous poster said the hotter the better but I figure there has to be some point where the tubes get so dang hot they don't sound good any more but what do I know. My EL84 amp doesn't have a bias adjustment so I'm stuck with whatever bias the designer chose. I guess my JTM45 could be biased too hot...?

[JimEff]

If my amp(s) were biased too hot, would this be the effect I'd hear? (ratty fizz after tube heat-up)

[Jef Bardsley]

Try turning down the input and turning up the master.

[saltydogg]

No, usually tone gets better the hotter they get.

This.

[evets618]

Ear fatigue. And it may not be your amp.
Is your drummer cymbal-happy?

[Greazygeo]

If my amp(s) were biased too hot, would this be the effect I'd hear? (ratty fizz after tube heat-up)Either your bias is set too high, or your transformer is getting too hot and mushing out.

My old Marshalls do this on 4 hour gigs. The transformer gets hot towards the end of the 3rd set.

[Theroyalconsort]

on the fatigue issue try waring some ear protection for a chunk of the gig and see of you still have the same issue.
Question...
Are you letting you amp wam up for 20 or so mins befor sorting the settings?
can be a big issue

[JimEff]

Either your bias is set too high, or your transformer is getting too hot and mushing out.

My old Marshalls do this on 4 hour gigs. The transformer gets hot towards the end of the 3rd set.

Finally, someone who understands what the hey I'm talkin about :banana

(no offense to the other posters). But cymbals? Come on! You guys gettin paid per reply? :sarcasm I think I know the difference between a raspy guitar tone and too much cymbal noise!

I'm gonna assume I've got these amps biased too hot and do the necessary checks...thx...

[antbosca]

Just chiming in to say I notice the same thing with some amps. I had an old Silvertone that did the same thing. Also, if my Rivera R30 sounds perfect when it is cold, it will be mushy and overly bassy when it is hot.

Both those amps are a little skimpy on the transformer specs so I tend to agree with Greazygeo about that.

[rockon1]

Finally, someone who understands what the hey I'm talkin about :banana

(no offense to the other posters). But cymbals? Come on! You guys gettin paid per reply? :sarcasm I think I know the difference between a raspy guitar tone and too much cymbal noise!

I'm gonna assume I've got these amps biased too hot and do the necessary checks...thx...

Im pretty sure he meant ear fatigue from loud cymbals. Maybe try running a fan at the back of the amp to keep it cool . Bob