Originally Posted by Downunderwonder
Dude is asking about preamp tubes. 12AX7, 12AT7 etc.
The driver tube is usually a phase inverter (PI) of some sort. The 12AU7 and 6SN7 are low gain tubes ideal for use as phase inverters. 6SL7 works great, too, depends on the chosen topology, gain, biasing / desired distortion characteristics, etc. So even a 12AX7 can work fine.
I really like the octals for bass, 6SN7, 6SL7, but 6N1P is good, too.