Something wrong with Studio pre Lead channel

[hyukjoon22]

Hiya people
I really need some help with my Studio pre.
I was just fine this morning, afternoon, I was playing it for about 3 or 4 hours and it was perfectly working.
Then I tried to swap some tubes in it with some from my Quad to see if I could get more headroom on the clean channel.
After swapping a few times I just decided to leave it as it was, but suddenly the Lead ch. started sounding so fuzzy, narrow, as though it's played through some sort of phone filter.
there's no bass, and the attack is very late? slow? and too much sizzle on the top, however, the Clean ch. works perfectly.
I've tried to change the tubes on this Studio pre several times and nothing's changed.. It still sounds rubbish.
I don't think I've touched any resistor things while working on the tubes..
Can anyone guess what I should do to get my Lead ch back?
Please help me!! Thanks in advance..

 

[BENNY]

dude that sucks. i know absolutely nothing about electronicall things at all. so i cannot help you. one person who may be able to steer or stear you in the right direction is james at peters amps. i know back in the day he was one of the few people who would mod mesa studio pre's give him a shout. i cannot gaurntee he will answer ya or that he will tell you something other than i would have to see it. but it is worth a shot.

[email protected]

 

[elvis]

The only difference between clean and lead channel is V3. Try replacing that.

You may have also had an LDR go bad by coincidence, or because of a bad connection while swapping tubes.