I'm sorry but I just can't buy this. If you compare a 12AX7 and a 12AU7 at a plate voltage of 250 v the rp of the AX is supposed to be 62500 ohms whereas the AU is supposed to be 7700 ohms at the same plate voltage. Then there's the tranconductance issue; the AX is High MU- the AU is medium MU. While we know that you can throw a 12AX7 into any position on most guitar amps in place of ATs, AUs etc - I don't beleive that modern tube manufacturing has fallen to the state you suggest.I could be wrong though, but I hope not. Now I'm going to get to the bottom of this. I will post my findings.
Yng - the Drumcore reference had nothing to do with you- I was comparing my un-called for rudeness to the even worse state of affairs on that post at the time.