shepke said:
Thanks for the cautionary advice. I'm currently trying to get more humidity to the guitar and will continue doing this for another week or so before I try anything else. The strange thing is that I always keep my guitars well humidified in the winter by storing them in their cases with a Planet Waves humidifier. I also use a room humidifier and leave the guitar tuned to 440 (I play it all the time).
I moved last fall from Illinois to Ohio, and it seems that my current place is much drier in the winter than I'm used to, so this is probably at least part of the issue. Still, there are no other signs of humidity related changes to the guitar (like frets sticking out... etc), and because of this, I'm not 100% sure the problem is simply humidity.
I use light gauge strings and I'll try mediums for a while, as you advice. I don't think there's any structural danger in doing this. I've used mediums before on this instrument, although not for the past two years. Maybe that's the problem - the neck was used to mediums and over the last two years, using lights, it may have gradually changed. So far it plays fine with a very slightly higher saddle and I don't think anyone would notice that there's a problem at all without examining the neck very carefully. But I know, and it's driving me crazy.
Everyone tells me this is a very unusual problem and, in the end, I may have to take it to the Doc.
Oh, by the way, I saw the pics of your new/old F-50R. Damn, that's a nice piece of wood!
Shepke:
If you have a suitable straightedge, you should put it on your fretboard (strings off), and see if there is any relief at all. If there is some relief, or it is straight, it means the neck is fine. If the two ends (at the nut and end of the fretboard near the sound hole) of the neck drop off, then you have a problem. It will be impossible to know until you can verify that. If you have a straight edge that is long enough (24" or so) push the straightedge forward (towards the bridge) so that you can see where the straightedge contacts the forward edge of the bridge. If it passes over the bridge or just barely contacts the top of the bridge, this is fine. If it contacts the front edge of the bridge, you may be looking at a neck reset; the further down the front edge of the bridge, the quicker it will be required. If it contacts the soundboard in front of the bridge, and immediate neck reset is in order.
If the neck does have relief, but you are still having playability issues, it means that the soundboard has shrunk some amount, and with that the bridge has come down in relationship to the neck. The solution to that is to try to raise the humidity so that the soundboard goes back to its proper shape. This should allow the bridge to go back to its previous level, and allow the use of your shorter saddle. You may want to consider humidifying the entire room in which the guitar(s) reside, and leaving the guitars out in the open, if that is an option for you.
If you have a drop off on both ends of the fingerboard, the neck is back bowed, and may need to be heat pressed. Backbow has more to do with the wood in the neck than anything else. Heat pressing can address the problem, if it isn't too severe; It should restore the neck to being straight (without strings). With strings on, it should bow forward some, which can be adjusted with the truss rod.
Necks don't get "used" to string gauges. The only thing they react to is the tension being applied by the strings (and the counter acting force of the truss rod). The neck will try to return to a stable state (ie. straight, or whatever position it was when it was built) without truss rod counter pressure, no matter what the strings being used are. If the truss rod is used to adjust relief for medium strings, the neck will straighten out (have less relief) if light strings are put on. You have however, stated that the truss rod in your guitar is loose, so any contribution of the truss rod is eliminated. If the neck happens to have been built with a back bow, then it will have a backbow if the string tension is lowered.
Kostas