Despite having owned tube amps for a few years now, I've never gone through the trouble of changing the tubes in any of them. I guess for me it was that sort of part that you don't change unless it died or is obviously on its last legs.
I've recently built a Champ clone with a JJ ECC83S and a JJ 6V6, and although very pleased overall with the sound, there was something that kept bothering me. The highs were just where I wanted them (i.e. not piercing) but the bass was a bit boomy and overwhelming. Tried fitting a tone control but didn't really like the result, as I lost some of that smoothness that I really liked.
Then I kept reading quite a few opinions on the JJ 12ax7, saying it was quite dark and might make an amp sound a tad muffled. So I purchased a Tung-Sol 12ax7 from Karltone and did the swap this morning.
Amazing! The bass is still there, and I'd say the amp is still a tad on the dark side overall (which I like) but that boominess is just gone. Everything is a bit clearer and the frequency range more even.
I honestly didn't think I'd see such a difference - but I guess with just the one 12ax7 and such a simple circuit around it, the valve's character comes through a bit more.
Any of you got drastic results when changing valves in your amp as well?
Yeah, in some cases it can make a big difference. Tonight I got my ac30 that was sounding dull, constricted and lacking in headroom, and made it much clearer, fuller and louder. And my ac100, which sounded fizzy with the presence on anything but 0, now sounds great with the presence at half.