Finding mechanical rattles in classical guitars

[Eric Gleason]

A customer brought me a new-ish classical that has a few dissonant rattles on certain notes, mostly around the 6-9th frets on the low E and A strings.  It's not fret rattle, and appears to be coming from the bridge area. 

Nothing I do seems to make a difference.  I've checked for bad glue joints on the bridge and the braces, checked for cracks, snug fit for the saddle, changed strings... no improvement.  This is the second classical that's stumped me with this problem.

Does anyone out there know of a possible cause and solution?

[Palle Clausen]

Does it have a pickup?

[Frank Ford]

First off, I can offer a link to my BUZZ DIAGNOSIS pages:

http://www.frets.com/FretsPages/Luthier/Technique/Setup/BuzzDiagnos...

If you go through those pages, you might get some ideas.

I can recall one really nasty classical buzz tha drove me completely around the bend.   After chasing down everything everywhere and poking glue under the braces I thought were possibly responsible, I checked every inch of the linings and wore out my knuckles rapping on the guitar for hours over a period of weeks.

In absolute desperation I finally concluded that the only thing I couldn't check was the bridge-to-top joint.   As a final effort, I removed and reglued the bridge.  When I took the bridge off, there was no sign of trouble under there.

BUT, once the bridge was reglued, the buzz disappeared.

Hope that remains a unique case for me. . .

[Greg Mirken]

Just because the sound seems to come from the bridge, don't leave out the neck, headstock, and tuners.

BTW, do you know the outcome of the first one that stumped you?

[Eric Gleason]

The first one that stumped me never got resolved.  It had a couple of cracks in the top that got repaired, one of which extended under the bridge and I got some glue in there and clamped it well.  It looked like a tight joint.  There may have been a loose brace that I fixed too.  But I never found the source of the buzz and spent a lot of time on it.  I had to resign myself to just billing the customer for the time spent fixing the cracks and brace, and ate the rest of the time.

In this case, the guitar was bought used on ebay (was in new condition), and my customer got a return authorization before I investigated any further.