MKII-A and MKII-B differences

[Power&Volume]

Title says it. I know the effects loop on the MKII-B is the big one. How about functions of switch push-pulls? Circuitry?
Any options from one to the other that they did not share?

 

[James]

I'm not sure about the circuitry, but the push/pulls are the same. The IIA had a switch for V1 that allowed use of a 12AX7 or the fetron, while the IIB was 12AX7 only.

A few other differences are that the later IIBs had the Simul Class option, and I believe the SUS-4 mount for the combos was introduced sometime around 1982.