Champ 12 hum on start-up

[strickland4218]

I have a Fender "red knob" Champ 12 that is making me nuts. I have a loud hum that starts about 2-3 seconds after powering on and then discipates after about another 2-3 seconds. After that time the amp sounds great and has no other hum issues. Anyone have an idea of what might be the problem??

[stokes]

My guess would be that the filter caps are taking a few seconds to fully charge,not familiar with that amp and no schematic,but I think it could be normal.

[Enzo]

I would say that any noises it makes in the first SIX SECONDS, after which it works fine aer nothing to be concerned over. Tubes have to warm up and not all do so at the exact same pace. SO if one tube warms up a little faster, it them amplifies the wake up of another. When I first turn her on, my wife makes funny noises for a couple seconds and then stops. Coincidence?

[Paleo Pete]

If it happens only at startup and goes away, it's probably not a real problem, just amplifying some part of the warm up, as noted above. I would turn it on with the volume all the way down and not worry about it, as long as it works fine after that few seconds.

Schematic if you still need it, and general info on that and most Fender amps at the Fender Amp Field Guide

[tubeswell]

When I first turn her on, my wife makes funny noises for a couple seconds and then stops. Coincidence?

Maybe she needs to be warmed up more slowly

[Enzo]

Are you kidding? The game is on on the TV. Got no time to waste.