[ricmon]

Hello team AVA I  have had my TR-7 upgraded to an Ultra II in Jan 2012.  My question is concerning tubes.  Should I continue to use 12AT7A tubes in the line section or 12AX7A tubes?  The original 12AT7A's we left in after the upgrade.

thanks
Ric

[avahifi]

Continue to use a 12AT7 tube in the line stage.  They are a higher current tube then the 12AX7 tube and are biased on harder.  A 12AX7 is a bad choice for your line stage.  It trades off higher voltage gain (not needed in this application) for lower current output (which is needed).

Frank

[ricmon]

Hello Frank thanks for the advice.  The pre is just a great piece of gear and was just thinking of getting a back up pair of some Telefunken's and wanted to make sure that I was getting the right value tube.

[ricmon]

One last thing. Should I keep using the 12AX7's in the phono stage?

[avahifi]

Yes