I'm probably "shedding" some credit here, but I think I can give you some what of an answer to your delima . first , I use the same mic cartridge ( Shure R-65 ) that every one else uses, so it's not a matter of different components. the main thing that I see right off, is you're comparing the E/Q mix of a "C" to that of a "D" and that just won't work. The "D" has a lott more mids and highs than the "C". I suspect that you're finding that you have to cut the lows a lot more on the "C" than the "D". this is a common problem that most of us don't think of at first. There are several was to solve this problem, but the key is, you will have to set the E/Q different for each different key accordion that you use in your performance. I know that Chris Miller uses a seperate mixer for his accordions ( he uses 3 or 4 different ones during a normal performance) and sends the final mix signal from that mixer to a single channel on the main PA. I use a Boss G7 E/Q on my accordion. This gives me the "on stage" controle of my E/Q. Once you've used this method a few times, you pretty much know where to adjust the different freq. to get the sound you want, between the "C" and "D" . Hope this helps.
Thanks Jude, I kind of suspected frequency vars between C and D having something to do with it. Both accordions go thru extensive individual pre-gig eq'ing but yours needs minimal adjustement compared to Larry's C.
Thanks all for you input.