What's wrong with my Amp?!

[nunonut]

I have a Crate GFX 2200 ,three channel head running into a 4x12 Celestion Greenback cab. I've had it for several years, and its always sounded good, but recently took a turn. Now the lead circuit, when the distortion is turned all the way up, only sounds normal when the volume is at 3 or below (out of 10). Turn it up any higher, and my tone goes straight to hell. It sounds like my cabinet is stuffed with socks; absolutely horrible. Any idea what's wrong?

[Erik19846]

Hello...

check the tubes!!!

[nunonut]

Sorry.. I should've mentioned, I guess, that the GFX series are solid state amps...

[Jim Wintringham]

If you are trying to isolate the trouble, try to 'pin down' the exact trouble.
1. Is it the amp, or speakers? Try to hook up another cabinet.... mabey a friend (with a GOOD amp) or local music store would let you connect up.
2. If it is speakers.... are they all bad, or just 1? Try disconnecting them 1 at a time to check.
3. If it is the amp.... turn it over to a tech, if you are not comfortable poking around.
4. If you are not uneasy...... pull out the circut board and look for psysical evidence of damage (burnt components, broken connections)
5. High volume use puts maximum strain on power portions of the circut..... look closely there...look for 'cold solder joints', points that got hot enough to melt the solder, then cooled to leave poor connections.
6. If it is only the lead channel..... check the pots that are part of that circut.... turn them....tap them.... if they are noisy.... a LITTLE lubricant...like wd-40 thru the stem.
7. Without schematics, componet failure would be very difficult to pin down...... time to get a tech!