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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.

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Steve Smith
"Music is what feelings sound like"

Steve--Did you mean .003" rather than .03" on the relief?
Nelson

Steve one thing that may come into play here is the RH when you did the set-up compared to the RH when you noticed the higher action.

If the guitar was dry when you set it up and then the guitar has been in higher RH since the dome of the top would possibly rise causing higher action. You mentioned a humidity crack so this came to mind.

It is pretty normal for guitars to change and need adjustments over time, lots of them come in twice a year, in the winter when they dry out and get low action and buzzing, and again in the spring/summer when they get all swelled up with humidity and the action comes up. It sounds like your guitar is starting to show signs of aging, top cracks and bellying behind the bridge, all pretty normal stuff. Keep an eye on those braces, i put a large mirror inside, and look at the braces while pressing down on the top over each brace, to see if they flex open.

Many people keep two saddles with their guitars, one tall one for winter, and a shorter one for the summer.

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Jordan Aceto
Ithaca, NY

Nelson, you're right - .003".

Perhaps it's a combination of slightly more tension and an increase in RH. We've had pretty steady rain here for the last 2 weeks or so. Also, this is the lowest I've set this guitars action since I've recently needed to play lots of bar chords up the neck. Previously I was mostly flat picking or backing up bluegrass so the higher action wasn't a problem.

Jordan, I'll try the flex test tomorrow.

If I can't find any more problems I'll assume it's a combination of more tension and increased RH along with having the action lower than I had before. I'll fix the crack and then trim the saddle to get the setup right again. This fall I'll just make another saddle for the winter if I need to. Of course, by then I hope I'll be playing one of mine.

_________________
Steve Smith
"Music is what feelings sound like"