12at7 with 12ax7 tubes

Thanks Doak.
So much for that experiment.

I beg to differ. The links given do state that these tubes are interchangable. I have done this as mentioned in my setup with no ill effects. Of course Sebrof the decision is your call. Good listening.

Actually, there are some semantics involved, as the 12AX7 can be replaced with a 5751, 12AT7 or 12AY7, but the 12AT7 can only be replaced with a 5751 or a 12AY7. ERGO, "interchangeable" may not be the correct word.

Rodman or anyone else, have you actually substituted 12AT7s for 12AX7s or other swaps mentioned in the links?

It would be great if we could swap tube types but the Tube Store writeup says:

"These substitutions can also work in home audio amps, but we don't recommend trying this unless you are having trouble finding the correct tube type for your amp."

Yes- and for decades. Guitar, microphone pre, and home audio amps. The AT's are usually slightly less microphonic/noisy, and sometimes it's nice to have less gain in a driver stage. The 6201 tubes are especially nice in that(quietness) regard. I don't have anything presently, that uses the AX family, but not much has changed in tube circuit topography(input/phase splitter/driver stages) in the past 40 years(how long I've been paying attention), outside of the quality of the parts used in construction. I do have a pair of gold pinned, triple mica 6201's, left over from an amp that I was building, if anyone would like to try them(free).