Preamp or Poweramp Tube?

[Goldtop]

I've noticed a change in the tone of my Mark III combo in the last couple of weeks. I started getting a thinner and more crispy type of tone. Where before I had a nice thick and smooth sound. What would be more likely the problem, a preamp or power amp tube?

 

[Boogiebabies]

How old are the power tubes?

 

[Goldtop]

It's a Simul-Class amp. The EL34s are about 2 years old and the pair of 6L6s are about a year old. I'm running 6L6 STR 454s and EL34 STR 442s.

 

[axwielding1]

I'd bet on the EL34's. I got mine real toasty running in class A and loud... I ended up getting 4 6L6. In class A the tubes run really hot....
ax. 8)