I’m currently reading Doug Self’s Small signal book in which he ascribes the Superbal input stage to David Birt of the BBC (ref to a paper presented at the IOA 1990 Windermere conference)…Which is rather puzzling as I thought it was one of your designs from the 70’s….I remember Steve Dove enthusing about it at an Aprs show I think (age you know)…can you set the record straight please.
It’s great to see clssics like the 828 and STM8 being discussed….Does anyone have a working ABCM?
It’s entirely possible that someone else thought of the same idea…. but I drew it on my white-board at Windsor in 1972…. and the drawing stayed there for a couple of years! It was actually an idea that came from discussions about mixing systems…. the obvious advantages of balanced mixing buses; the original ‘superbal’ was the first balanced ‘virtual earth’ system, and we used it on a number of mixers later.
I have just been reading the ‘personal memoirs’ of David Birt and thoroughly enjoyed his sense of fun in the face of finally getting a job at the BBC on his third attempt.
I’ve tried to get the draft of the 1990 paper but failed….. if David published the idea of the ‘superbal’ in 1990, then it’s most likely it was me who thought of it first!
I would appreciate getting in touch with David Birt if he’s still around.