yep, thats pretty much what i was thinking.
I would like to mount the mics permanently inside the grille which covers the working parts of the accordion, although another idea might be to have the mics mounted in an external bar which velcro´s onto the grille. Either way I´ll be careful to avoid vibrations.
I´ll balance the mics with trims exactly as you said. As it should only need a small adjustment, it might be an idea to use a fixed resistor in series with the pots so that the pots can adjust more sensitively over a smaller range.
Here´s a sketch I did of the circuit a few days ago.. The trim pots are still the normal way round, so taking into account what you said about them interacting should redraw this as in your passive mixer design...
I´m going to stick with having a level control on the pre-amp box, I know I could leave that to someone at the mixing desk , but I think it´s my prerogative as a player, you don´t see an electric guitar without a volume knob after all. Definitely going to shield the box for that.
I still want to go as low noise as possible on this, as near as I can get to a professional mic system. As I said, it isn´t just for stage work and noisy environments, I´ll want to do stuff in the studio too. So if theres any issues there I´ll try the active mixer with a quad amp as Nigel suggested.
I do imagine I´ll have problems with key noise, but then I did recording with room mics too... I just need to work on my technique for that!
Nigel, glad to hear you daughters been playing a bit! I do sypathize with the sound engineer, it´s a bugger trying to get a mic close enough to the moving side of the accordion on the stage!
Cheers
Wilf