Mysterious buzz, ongoing problems

[sirwhale]

Hi

On my Blackbird lucky13 (no truss rod), I have a buzz issue with the 4th string.

The worst point is the second fret; open and 1st frets are fine.

3rd fret less of a problem, 4th fret less, 5th fret only if played to get a buzz (but doing so shows that with this technique it is worse than the other strings.

I have tried many brands and gauges.

There doesn't appear to be a high fret. It has low relief but it isn't too low (other strings seem fine). Action is 1.75mm-2.4mm.

I've been to two luthiers here in Barcelona. One just looked at the string-fret distance when fretted at those notes and said it was fine and "illogical" - he knew nothing about CF guitars.

The other luthier was more knowledgeable and stated that there was a problem with the 4th string, but he couldn't see any obvious high frets. Relief was fine. "Change the strings to see what happens" (it hasn't helped... again). Currently got 12-54 Pure nickel John Pearse on.

He said that he thought the sound was coming from the bridge, I tend to agree that it is more that area than a sound coming from the neck. He said that I should consider looking there, but that he knew little about working with carbon fibre, so what he could do was limited.

There doesn't seem to be anything loose that could rattle.

The guitar has no bridge plate and is slotted.

Any ideas anyone? This thing has been driving me mad for months...

[jonfields45]

Sometimes I have gotten a buzz on some guitars with relatively flat fret tops and wound strings. My theory was one winding was sitting on the fret and the next wrap was buzzing against the fret. The buzz sounded like it was coming from the guitar body. With the two guitars I've experienced this with it was not highly repeatable, and came and went. Try replacing the offending string with something lighter and heavier gauge (will move around the windings). Also an Elixir polyweb string might have enough coating to not buzz. For those guitars, which I eventually sold as every guitar I ever own, I decided to live with it after I felt I understood it. If this pans out, it might pay to give the offending frets a narrower crown.

[pops]

I have had guitars that had buzzes that were hard to find. A buzz can travel and sound like it is somewhere it is not. If you think it is at the bridge how does the saddle look? I have had the truss rod buzz when fretted in certain positions, check the truss rod for tension, even if it has tension it can buzz as it may be loose in the slot. I would think carbon fiber may have sound travel easier than a wooden guitar so it may be harder to find.