Open A string buzz.
 

Hello all,

I have a buzz on my open A string. More of a rattle, I had a luthier look at it and they shimmed the nut. It was fine for a couple of days now it is back, not as intense, but still there. The odd part is that my stopped A on the E string has the same rattle. What makes this even odder is that if I stop an A octave the rattle goes away. I know my bass has a wolf tone around the A and I was wondering could this be an issue caused by the wolf tone or is this more to do with the nut needing to be further shimmed? I will go back to the luthier when I can be without the bass (in case it needs to stay over night), but figured I could get some advice here too.

Thanks

Any way that you can have someone else play the offending note, so you can get up close to the bass and try to find the source? You might even roll up a piece of cardstock to isolate where you're hearing the bass to really zero in on where the sound is coming from. Since it happens on two different strings, I'd think that it's coming from the bass somewhere, and based on the vibration of that pitch. Perhaps a sympathetic vibration on the afterlength, or a slightly loose bass bar. Also, try extending your endpin much longer and see if the buzz persists; sometimes the endpin inside the bass can oscillate and cause a weird vibration at certain pitches.

I don't think it is the end-pin because I have it cut so that when it is extended to playing length there is maybe an inch or two inside the bass. I'll see what I ca do though, I hope it isn't the bass bar.

P.S. the problem only occurs when I play the notes pizz. No noise with the bow.

I would think the bow sound might cover the noise.

One more to check - the pegbox. If the strings in the box lightly contact each other where they cross, sometimes vibrations can cause them to buzz a little.

Peg screws can rattle at a certain frequency if one is loose (not if you have hatpegs). Maybe this is the reason and happens at the frequency of the A.

I once had a buzz that was coming from a little flake of wood where the top met the neck joint. After I finally identified the problem, all I had to do was push the flake down. If you've got an old beat-up bass, I'd go over the entire body to see if maybe a stray piece of wood is contacting something...