There is an Acadian D box for sale from Canada on eBay. One of the photos shows the reeds exposed, and the 3 and 4 stops appear to have "+7 1/2" and "-7 1/2" written respectively on the top blocks.

Is this a 15 cent dissonance between 3 & 4?

I have taken it for granted that a wet-tuned instrument was off on one register, and thus could be played dry with that stop shut. That would not be the case with this box, if I am correctly interpreting the notations. (Then again, they could mean something entirely different.)

If any of you tuners could enlighten me, I would appreciated it.


Nedro

I think, not sure, that is referred to as "light mussette" tuning. That is not uncommon in Canadian melodeons. A standard wet tuned accordion would have one of the mid rows tunes at A440.

That would be 15 cents difference between the mid rows, but it would sound a little different than an accordion tuned 15 cents wet, because the L and H rows aren't 15 cents off of either M row. Slightly different sound. Could be changed fairly easily.

I think that is Marc's tuning for Quebecois music, if so the 3rds and 7ths probably aren't flattened.