Amp help PLEASE!!!

[J-Fuzz]

I have a Vox AC30C2X amp. I used it for the first time in months today (I have been away from home for at least 2 1/2 months). When I used it today, I immediately noticed a distortion that shouldn't be there...especially in the low end. I first noticed it when the amp's tremolo was on. Then I turned everything I had off and realized I could't get a clean tone at all. The amp's backside has been sitting in a position where the sun has been hitting it fairly hard for a couple of months. I don't know if that would have anything to do with it or not. It doesn't happen all at once...just as an aftereffect (immediately after the chord or whatever is played). If anyone has any ideas and/or suggestions please help a dude out. Oh, and this amp has only been used (since it was bought new) about 10-15 times for about for about 3 hours at most each time, and not at very loud settings.

[MEC]

If it is still under warranty, I'd go that route.
If not, I'd start by checking the preamp tubes. If you have a spare that you know is good,
just swap them out one at a time and see if you can find the culprit.

Just make sure you turn the amp off while you are doing the swapping.

[J-Fuzz]

Just make sure you turn the amp off while you are doing the swapping.

hahaha...I will try some new tubes out first I guess. I do wish the amp was still under warranty though. I hope it's not a faulty transformer or a speaker. New, replacement alnico blues are somewhat expensive for me right now.

[Ancient Astronaught]

I agree with MEC sounds like a preamp tube.