I have a carvin legacy 212. Ive been playing it for about five hours with a tube screamer and i noticed a crackiling noise. so i look at the tubes in the back. all four have lights on the bottem of the tube but i noticed one of them had an orange color at its base. but it only lites that part when i actually played. have i been playing to long with the screamer on? or is time to change that tube?
thats not good, all of them should be orange.
from your description, I can't really tell, but you will want to get a new set of tubes and start from there. If it's alright then your good, if not, you'll have to go further in your troubleshooting.