I was told that in the early seventies, some models were release with the 'B' designation as a way of avoiding to have renegotiate import tariffs.
A 2265 is nothing like a 2265B nor is a 2285 anything like a 2285B
I stand corrected.
That explains a lot because I've only seen 2 side by side and it so happens to be the 2250 and 2250b.
My buddy has both, I assumed they were all like that
For what it's worth, I have a 2220B and had a 2220, and after much deliberation and careful listening, I decided that I like the sound of the 2220B more and sold the 2220.
Everyones ear is different but the fact is the 2220 and the 2220B are very different from each other. Most notably is the 2220 is cap coupled while the 2220B has a relay.