Long time since looked into valves have just bought a Fender prosonic..nothing wrong as far as I know with the valves...but for future reference would it be worth changing any of these
mine has chelmer premium gz34, 5881wxt x2, fender 12ax7a's x3 then sovtec 7025, fender12ax7a, sovtec 7025 so odd mix I guess
I have a Fender 'Evil' Twin and found the following:
The Fender 12ax7s tend to be re-badged Sovtec 7025s anyway. The better sounding alternatives ( clear with big sound stage ) were JAN/Phillips 12AX7s from Watford Valves. If you like lower gain, but more detail, substitute Valve 1 with a Jan/Philips 5751. ( Stevie Ray Vaughan replaced
all his pre amp valves with 5751s ).
For outputs, I prefer 7581a types. These Bias like a 5881/6L6 but tend to give a big clean sound.
If you like early breakup and more compression, use N.O.S. short base 6L6WGB types. You will therefore benefit from some 'Harma' hot graded 12AX7 pre amp tubes from Watford valves or near offer.
I do not work for Watford valves - but they do seem to be the 'BKP' of valve selection. The website, or the owner ( Derek ) also can advise according to your tonal tastes.
Happy tone hunting !
F.F.