Back buzz with medium strings

Bob V

Member
Messages
1,185
I recently changed to medium gauge strings on my 1994 Guild D30-Blonde (last year that model was made in Westerly RI, I think). Also replaced the nut. With D'Addario medium gauge strings (.013 high E), the trussrod is adjusted for .006" relief (same as the Mfr. spec), the action at the 12th fret is a little lower than 4/64 treble and 4.5/64 bass (spec starts at 4.5 to 5/64 treble, 5.5 to 6/64 bass). The frets range in height between .039 and .041 and the nut slots were cut until they hit feeler gauges stacked to .051" giving "nut relief" or action at the first fret of .018" (spec is .020 to .022).

So here's my problem. When I grab the A string at the seventh to the ninth fret the string makes a noise slapping against the frets between my finger and the nut. I think this is called "back buzz." There's no buzz in the string between the fretted point and the saddle, and the action plays very nicely even though it's quite low.

Should I (1) look for a single high fret around 3rd to 5th frets, (2) let out the trussrod tension to get a touch more relief, or (3) bring the nut slots up by filling with bone dust and CA glue?
 

Rosewood

Member
Messages
1,859
Check the relief from the 1st fret to the 14th (if that's the fret at body to neck joint) and see if you still have some relief. If your using a straight edge and the fingerboard has a rise at the body end this will throw your measurement off. Use the strings as a straight edge if you don't have a shorter straight edge.
 

Bob V

Member
Messages
1,185
Good advice, my 18" straightedge ran up onto the fretboard extension and there wouldn't be any relief there. Anyway, with a 14" straightedge spanning from the 1st to the 14th (body-joint fret) the relief still measures .006"

It's not a buzz as much as a loud metallic slap when I grab the open A string and fret it between the 7th and 10th frets, but it is coming from the part of the string between my finger and the nut. Should I be looking for a high fret? I have a small 6" combination square and the beam, when removed from the blade, makes a good tool for rocking across three frets at a time to see if one is high, but I'd have to remove the strings to get it in there (not like the Stew Mac triangle thing which I suppose is thinner).

It would be a lot of work to fill the nut slots and cut them all over again just to get .002 to .004 higher on the bass strings and I'm not sure that would solve the problem.
 

JohnSS

Member
Messages
932
If you are happy with relief, here's a painless mod to try, which I have used successfully on other acoustics in the past: take a flat toothpick and use it to shim the saddle. The effect on the action between nut to 9th fret should be negligible, but might help your problem. If it doesn't work for you, it's easily rectified.
 

Bob V

Member
Messages
1,185
Thanks, I haven't been sweating over the acoustic much lately (new ES-339 in the house, whole nuther story). I just realized from Frank Ford's site that sometimes back-buzz can be a sign that there's not enough relief. It seems like I might have read too much into Guild's recommendation for less relief when using heavier strings, so I'll try backing off the trussrod not a tad.
 

Bob V

Member
Messages
1,185
Thanks for the advice. I backed off on the trussrod nut and finally arrived at .009" relief where the problem disappears, but the action is still nice and low (4/64 treble, 5/64 bass, measured open at the 12th fret).
 




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