Two weeks ago I redid the setup (first time in about 8 yrs) on an HD28 which has been my daily player for about 15yrs (at least until I build something better). I set it up with John Pearce mediums on it but they didn't sound that way I wanted so late last week I replaced them with my usual strings, Martin SP Phospher Bronze mediums. Last night at rehearsal I noticed the action seemed high so I went home and remeasured it. The nut and the relief were ok but the action at the 12th fret is up about 2/64".
My gut feel is that the Martin strings do seem to have more tension than the Pearce's. Is the string change from one type of mediums to the other likely to have caused this much change?
The original setup was this: for the nut I fret at the second then just make sure the strings "tink" on the first. Relief is pretty flat, maybe .03". I run between 5/64" and 6/64" on the low E at the 12th down to 3/64" or 4/64" on the high E. I like a fairly low action.
The reason I'm concerned is that this guitar developed a humidity crack this winter from the tailblock to the bridge and I am concerned something else has popped loose. The belly looked to be about 1/8" (higher behind the bridge than in front of it). I checked inside the box with a mirror and didn't see anything obvious. I ran a spatula (about .010" thick) around the edges of the cross braces to see if I could feel a crack - nothing. Rapped pretty hard all over the lower bout on the top to listen loose stuff, nothing.
Anything else I should check? I'm off tomorrow so I plan to fix the humidity crack and would like to get anything else done that's needed.
Thanks for helping.