I've not played a low A on a regular basis, only "fooling around" and that one year way back in college. But it always seemed to me that the intention was to get low A by playing low Bb and then adding the thumb key. Getting all three of those large keys with long whippy rods and arms and linkages to reliably close on the one thumb key always seemed pretty dubious to me.
That said, I have not had a modern low A bari in front of me for careful examination.
That said, I have not had a modern low A bari in front of me for careful examination.
