Have to crank preamp for power amp to make any sound

[TyphoidHippo]

Well, the title says the whole issue, really. Today, in the middle of the day, one of my power amps (an old Crown DC-300) stopped making any sound at all - unless I crank up the source pretty much all the way, at which point it starts working perfectly, albeit loud as hell. I can then turn the source back down almost all the way, and the amp keeps working... but if I take it down too far, the sound craps out rapidly until it's just silence, at which point I have to turn the source all the way back up again to get any sound from the power-amp. I did thoroughly eliminate all other possibilities (but won't detail that) - it's definitely this amp.

I'm kinda stumped...never seen this happen before - anybody know what it could be? The amp is pretty old - I've had it for almost 20 years, and it wasn't new when I got it, heh.. I do like it, though - perhaps only for sentimental reasons, and I might still be able to get a replacement part if I had the slightest idea what part was failing...Or if not - I'll just toss it. I don't know which to do, though - since I can't honestly say I have even the slightest clue wtf went wrong with this thing today

Thanks to anybody who can help

 

[Lt. Bob]

try cleaning the input jacks on it and the pots.
I have seen amps do this when they were dirty enough that it took a high enough signal to overcome the resistance of a dirty jack/pot to get things going.

 

[TyphoidHippo]

Hey, it was the pots - I didn't even think of that, since I always leave them all the way up. I just took them out and wired it wide open until some new ones come in.

Thanks! The antique Crown lives on

 

[dodgeaspen]

try cleaning the input jacks on it and the pots.
I have seen amps do this when they were dirty enough that it took a high enough signal to overcome the resistance of a dirty jack/pot to get things going.

Another good post. I had the same thing happen to an old amp I was using. I thought maybe it was cold solder joint problems so I stopped using it. Now I'll have to clean it and see what happens. Thanks Bob.