[Tim Bishop]

In an interview with Jess Oliver, he says:

"Model A-15, the A stood for Accordion. It was the same as the B-15 but accordion players liked to be assured it was designed for accordion. The B-15, B was for bass. The B-15N, the N stood for new engineering changes. The B-12X and B-18X, the X stood for extra power or extra effects like reverb or vibrato. As for the B15ND, I think that was the same circuitry only made with a printed circuit instead of an eyelet board. I'd have to dig up the schematics to confirm that."