Crate hybrid

[Dirtynasty]

Hey guys, I have a Crate TD-70 and although its a hybrid i do love the tone I get from it, I play hard metal/ punk and the raw tone suits me fine. The problem is it seems to have lost its gain, it sounds real muddy at high volume and even the clean channel distorts BAD when turned up. It didnt do this before so I thought it was the single 12AX7 preamp tube. I repaced it with a "newer" tube from another amp with little improvement.
I do plan on buying a brand new tube but do you think that could be the only problem? I have a feeling its more than just an old tube. I know Crate isnt exactly primo gear but this amp is 20 years old and I have had zero problems.
Is there anything I could look at that may need attention? Is there any other things I could do to mod or even help this amp live longer and sound better? I've heard about beefing up the heat sink, what eles could I do to improve tone and reliability?
Thanks.

[Enzo]

Isolate the problem.

Send the signal from the FX send to some other amp and listen to it there. Does it have the same weak crummy sound? if so, the problem is preamp related. If it sounds clean and strong, then the preamp part is OK.

Plug a signal into the FX return. How does that sound? Clean and strong or muddy and weak? That was testing the power amp.

And it could actually be the FX loop jacks themselves. Plug a cord from send to return and see if the amp wakes up.

And for that matter, try playing the amp through different speakers.

[castroalien]

This amplifier have a bias through trimpot adjustment ?

[Enzo]

Hi castroalien, and welcome

Dirtynasty logged in last nine years ago, so we won't get a response very likely.

[castroalien]

Hi castroalien, and welcome

Dirtynasty logged in last nine years ago, so we won't get a response very likely.

[J M Fahey]

This amplifier have a bias through trimpot adjustment ?

And in any case do not mess with the bias trimpot.