i'm sure tom might have posted about this somewhere on his blog, but i had some crackling from my sa200 the other night, and was told by my tech, jimmy @ Invalid Link Removed, that i probably have a bum preamp tube.
thusly, had my own little preamp tube shootout. it was totally informal, and frankly, i had just a bit of time before my next gig, so take it for what it is. had my trusty lakland bob glaub w/ stock fralin pickup, SA210 (thx bikeplate!!!), fat switch on, tone controls are usually just noon, along w/ the gain and volume. master to taste. and i replaced just the V1 (and later you'll see the V2), which was the culprit. i'm not sure what was stock. markings on the tube just say "12AX7-C", but that sounds sovtek'ish.
here are some thoughts:
EH 12AX7 - nice midrange, but top a little dull.
Sovtek 12AX7 - not too shabby and very similar to the original sound but a bit more fur ontop.
JAN Philips 12AX7 - scooped mids, steely bottom, airy top end, but overall ok.
RCA 12AX7 - airy top, chewy midrange, full bottom end (ended up being microphonic)
Mullard CV4004 - nice airy top end. impressive steely punch! but slightly bottom end shy compared to the other tubes.
Philips 12AX7 - similar to the RCA, but not quite as rich.
"made in germany" ECC83 - similar to the sovtek
randomly marked JAN 5751 - nice full sound. nice top end.
JAN Philips 5751 - nice thick midrange, but dull top end.
there you go. again, just some random thoughts.
i really love the sound of the RCA. nice rich sound that made fingerstyle easy, but again, it began to make some noise. but if you want PUNCH, the CV4004 is your ticket. it blatantly adds more punch in ways that took me off guard!
in the end, i put the JAN 5751 in V1, and added the CV4004 in V2, which gave me a nice combo of thickness and punch, while still being smooth and even sounding. i dont like too much hair on my sound, but do like that tubey presence.
