Reporting question for Vacuum Tube - 12AX7-A, Triode, Dual, High MU

Product:
Vacuum Tube - 12AX7-A, Triode, Dual, High MU

Question:
What is the difference in a 12AX7A and a 12AX7B tube? Would I have to re-bias my amp?

Answer:
The differences will be in spec and possibly some tonal characteristics but you do not have to bias preamp tubes so you can just replace your current tubes with these.