Q: My 1983 Martin HD-28 has a buzzing or rattling high E string. The rest of the strings sound great. A local fellow worked on the frets and smoothed them out and it plays well other than this annoying rattle. What in your view is the most likely cause? —Gerry Laverty, Richmond, Virginia
A: It can be vexingly difficult to diagnose string buzz. Here’s a list of ten possible causes that I look for. If this checklist doesn’t identify the problem, I sometimes resort to offering sacrifices to the guitar gods.
1. Low Nut Slot
This typically causes problems on the open note, but can sometimes create buzzing between the nut and a fretted note. If you suspect the latter, play the fretted note and then damp the string between the nut and the fret while the note is still ringing. If the buzz goes away you may need a new nut or “nut implant.”
2. Improperly Shaped Nut Slot
A string that bears too heavily on the middle or the back of the nut slot can buzz in a sitar-like way on the front of the slot. This can be corrected with a couple well-directed strokes of a nut file.
3. Improper Saddle Contact
Same issue as above, only at the saddle. This occurs most often on taller saddles having acute string-break angles.
4. Bad Strings
Buzzing can sometimes result from windings that have come loose from their core. I have even seen new, obviously defective strings with this problem.
5. Touching Strings
No two strings should touch in the area around the tuner posts. Custom nut spacing, replacement tuners, and oddball string gauges are the usual culprits.
6. Bouncing Frets
An improperly seated fret can elude accurate leveling, then bounce back up and continue causing buzzing problems. Superglue and a little spot dressing can get you to your next full fret replacement.
7. Neck Too Straight
The physics of string oscillation dictates that fretboards should rarely be straight and never bowed backward. Ideal fretboard shape depends on scale length, string gauge, playing style, and other factors. A good tech can optimize your guitar for your style and playing preferences, but cannot change the laws of physics. Sometimes you just need more relief.
8. Loose Joint
A loose brace, bridge, binding joint, nut, or any ill-fitting part can cause vibration sympathetic to a specific note. I hunt for loose joints by damping strings and tapping around the entire guitar. The fix is often easier than the diagnosis.
9. Loose Pickup
This sympathetic vibration merits a category of its own. The problem is often a loose cable which can be detected by damping the strings and shaking the guitar. Recently, I found buzzing related to a loose jack cover.
10. Sympathetic Truss Rod
Think of the truss rod as a big guitar string that can be tuned to a note that’s either sympathetic or not sympathetic to a significant resonant frequency. You get the picture.