Power Amp 😫?

[Joshua Tschetter]

Hate to ask, but what are the signs of a power amp going out? 😬

[Jerry Erickson]

With older amps, they blow fuses. With newer amps, if there's a problem in the power supply or output section,they'll sometimes power on but won't pass signal to the outputs.
What amp do you have and what's the issue?

[Joshua Tschetter]

Thanks for your time Jerry.

The amp is a Stewart PA-1000
Going to a Sarno Revelation pre amp.

Past two days it’s been acting weird, low volume and speaker crackling. Then it seems ok again for a minute, then the same thing. Back and forth like that till I power down and power the amp up again, and then again more of the same. It does sometimes behave for awhile thoe…

Thanks again.

[Cappone dAngelo]

Could be something as simple as a dirty jack - perhaps try cleaning them with a suitable contact cleaner and see if that fixes the issue? And of course eliminate other variables - like the cables, the preamp, etc. - before taking it in for servicing.

[Donny Hinson]

Hate to ask, but what are the signs of a power amp going out? 😬

You'll see it taking a shower, putting on clean clothes, and asking Dad for $20.


But seriously, the problems you describe sound like a bad connection or cold solder joint. Does a good slap or wrap on the amp when it's acting up make any difference?

[Don Downes]

Mr. Hinson, that is the best reply to a post I've ever seen.

[Joshua Tschetter]

Oh ya boys, have fun at my expense! 😂

Thanks everyone for your replies, I will check over all cables and connections.
Glad it ain’t the power amp. I really like that one and they seem hard to come by now a days.

Thanks again. JT

[Don Downes]

We're laughing with ya, Josh, not at ya. Those Maryland Terps have a great sense of humor!

So, I just looked up your pre-amp and amp. You should have mentioned that they're discreet components. Since the pre-amp is tube, and the amp is solid state, test them separately.

I would check the amp first. First, check that your speaker terminals/wires are not shorted. A stray strand of wire can cause issues. A lot of SS amps have a relay delay protection circuit so that if it senses a short or overload condition, it will prevent the amp from connection to the speakers. A solid state amp is usually either good or bad, and generally doesn't exhibit the kind of problems you mention. If you have another pre-amp, or a stereo receiver, or a DAW that has a "Line/pre-amp OUT", use those outputs to drive the amp and see if you have the same issue. No issue? Not the amp.

Second, if you have another power amp, or something with a pre-amp IN plug your pre-amp into the amp and see if the issue follows the pre-amp. If so, then it may be that one of the tubes in the pre-amp is either not seated well (this could happen if you move it around a lot for gigging), or may be beginning to fail.

Find out by the process of elimination what component is at fault.

[Dan Kelly]

I just went through a similar situation. MossValve Power Amp to the Sarno Revelation with a Lexicon 30DX. Went through EVERYTHING in those rack components.... AFTER all that, it was the Jack on on my Steel that had worked itself loose and the ground was weak and intermittently strong.

[Joshua Tschetter]

Ha I know Don, I don't mind being laughed at, either!

First chance I get I will go trough everything with a fine tooth comb.

Thanks for your time Gentlemen.

Best Regards, JT

[Jim Cooley]

If it's a dirty or slightly corroded jack, you can sometimes fix it by plugging into it and unplugging several times. Twenty or more times isn't too many. It might not solve the problem, but it's a quick and simple way to check.