For 12ax7, try a 7058 (RCA made good ones). They are cheap and sound amazing.
For 12at7, try a GE or Sylvania 6201.
A very good tube equivalency resource is:
http://www.duncanamps.co.uk/
For 12at7, try a GE or Sylvania 6201.
A very good tube equivalency resource is:
http://www.duncanamps.co.uk/