Inherent Difference - 12AU7 and a 12AT7


Can anyone school me on the practical differences between a 12AU7 and a 12AT7 input tube when used in a preamp? For example, all things equal is one of these tubes quieter than the other on average, does one have greater gain than the other, and is there any characteristic 'sound' to each of these tubes?
stickman451
Stickman as I mentioned they should work without issue but if you go to the web and look at the tube data you will notice significant differences in the voltage and current characteristics of these two tubes.

Kind of like driving a Porsche with a Chevy engine in it. It may work but it's not how it was designed to run it's best. I wouldn't spend a lot of money on nice tubes just to try it. But that's me.

Maybe just get some nice 12au7's like Rodman mention all he said are nice tubes. I have a friend that uses the EAT tubes and really likes them but I am not willing to fork up the money to try them.
The do make a AX7 Music Direct carries them. $225 a pair. That is what my friend owns.
EAT DOES make the 12AX7 tube, but it is referred to by the European moniker: ECC803S, which was the best of the best, for that tube family(http://www.gcaudio.com/cgi-bin/store/showProduct.cgi?id=501). The 12AX7, and the 6DJ8/6922(ECC88), are the two most popular 12 volt, 9 pin miniatures(most commonly used), in the industry right now. I'm certain EAT took that into consideration, when deciding what to manufacture.