When I send my D-18 to Brook, which should be a week this Monday, I'll put a set of 13-56 in the case.

It was a mistake dropping down a gauge. The lower tension just feels wrong to me. I've had Gibsons and used 12s happily but on this D-18 they're just meh.

Other Martins may well be happy with 12s 'cos not all guitars are the same. Can they be? Short answer: no. Long answer: hell no! :-D

-F