Hi Myles,
I'm fairly new around here and people tell me I should address this question to you. Thanks in advance for your help:
My grandfather, who turned 95 this year, is a retired electrician. A few weeks ago, when helping him move some things around in his basement, I opened a few of his old tool boxes and found several hundred old vacuum tubes. Being the owner of a couple tube amps, I'm intrigued by this discovery but digging through piles of tubes, I'm having a hard time figuring out exactly what I'm looking at. Specifically I found a whole bunch of tubes that look vaguely like 12AX7 pre-amp tubes. They're mostly from GE and RCA but I also found a Mullard and a couple Tung Sols. Unfortuntately, only a couple of them say 12AX7 on them. Most of them say 12AU7 and several of them have other designators that are greek to me. My question is, what is likely to happen if I pop a few of these into my Fender Blues Junior in place of the 12AX7s? Is it safe to experiment like that? Are 12AU7s interchangable with 12AX7s? Does anyone know where I can find a list of other tubes that are compatible with 12AX7s?
Thanks,
Jason