Received a 1949 D- 18 Martin in my shop for evaluation. Seems the bridge may be incorrectly placed from the factory. Problems:
1. bridge has been thinned , and , saddle height has previously been lowered , to improve high action , when a neck reset would have been the ideal solution.
2. 12th fret intonation check indicates the correct position for the saddle @ treb. E string to be about 1/8 in. toward soundhole from current position. This is not even over the bridge.
3. same situation for saddle @ 6th string...saddle should be about 3/32 in. toward the sound hole from the original position.
4. Martin indicates a scale length of 25.4 in is appropriate for pre 1960s.
5. My measurements ( using a stewmac saddlematic ) keying off the 12th fret ( nut to 12th and using same measurement from 12th toward bridge ) place the saddlematic treble wire marker at 1/32 in. shy of the bridge ; and, 8/32 in. shy from the crown of the saddle where the 1st string crosses.
Have any of you run into this on the D-18s before? Or is this particular D-18 just a friday made guitar .
My 13 years of repair instinct tells me that the bridge is in the wrong place . That I should make a new oversize width bridge ,and , cut the saddle slot in the correct new position. Oversize to cover up the bridge footprint outline on the top. BUT THIS IS A 1949 VINTAGE MARTIN we are talking about here. Although I have much experiance in all phases of guitar repair, and feel that the intonation would be much improved , and a neck reset would greatly enhance the playability of this instrument, I am more than a little apprehensive about ruining the value of this instrument by making necessary design improvements on the bridge.
Any thoughts ?
I'm SURE you have checked it, but then, intelligent people are perfectly capable of being fooled, just much less often than the rest of us, sooo...
Is the nut correct? String height good? Is the position of the nut relative to the first fret good, and do the slots end in the right place?
Is the fretboard original? Has it been replaced? Has this guitar has some kind of "slip the block" reset done in the past that screwed everything up?
Something sure smells here...
Postwar 1940s Martins frequently have the bridge out of position - to the rear and playing flat. And, it presents a nasty problem to correct the intonation. Most of the time, we crowd the saddle as far forward as we can to avoid using a wider bridge or trying to move a standard-width one. Most of us can tolerate flat notes much better than we can sharp ones.
By the way, 1/8" movement of the saddle changes intonation by a bit less than ten cents:
Why no pictures yet?I enjoy lookin' at old Martins.......let's see it!
Yes, some late 40's Martin's are slightly flat, from the day they were built. I have a 1949 00-18 that the saddle is probably back 1/8" more than it should be.
You can correct the problem when you reset the neck. Just shorten the heel slightly during the reset, doing so you move the fretboard closer to the bridge, shortening the scale, thus correcting the flat intonation. Being the bridge has been thinned it may need replacing, but it can be replaced with an exact replica and not modified in any way.
That is what I would do.
Also as Frank said, flat intonation is easier to tolerate than if it's too sharp. Using a capo, and just the fact that strings are stretched during fretting, is a good reason to have intonation slightly flat at the 12th fret.
On a guitar with correct intonation, I have found that the measurement from the nut to the center of the 12th fret, when moved from the center of the 12th fret to the saddle, that distance will end up at the front edge of the saddle(or 1/32" before saddle), this on the first or high E string. The low E will be set back farther yet of course.
I appreciate your feedback . I have been gravitating toward the string length / neck reset fix myself. It should be an easy to do , and , aesthetically un-noticeable , and , value holding repair solution. I will have to make a new bridge , but , I will duplicate the the original design to replace the over-thinned one , which is on the top now.