by Ty_Bower » Sun Oct 14, 2007 8:24 pm
I don't have my Mk3 running yet, but I've played with the 12AX7 socket in the DIY ST-35.
Of course, the 12AX7 works just fine. 5751 and 7025 are also popular substitutes. You can also try the ECC83, which is the European designation for the 12AX7.
I've found that each different tube seems to impart a slightly different quality to the sound, but I'd be hard pressed to say which one I prefer. I'd wager that any differences I'm hearing might be attributed to variations from one tube to the next, as much as differences due to actual construction.