Double Bass Buzz when playing F

[maphiles96]

Hey,

So first off I hope this is the right part of the forum to post this.

I've somewhat recently gotten my first Upright. It's a carved flat-back of unknown age and origin (the luthier I took it to assumes it's German and was made sometime between 1900-1930 but who knows)

I've had some issues with the Bass here and there, mostly due to cracks/seam separations that existed when I bought it plus a lower saddle crack that has been fixed.

Today I noticed that when I play an F on the D string in 1st position or the same F anywhere else on the bass there's a short but fairly loud buzz that I can't seem to locate. I noticed 2 spots where it looks like a seam might be separating, but also I was told that one of the back braces might be coming loose last time the Bass was at the luthiers. Now my question is could this sound be caused by the back brace loosening further and is there a way to find out if that's the case?

I currently don't have the money to have the bass opened up, so if this could be the brace is there maybe a way to sporadically fix it until I can afford to have it repaired properly?

 

[RSBBass]

It is a sympathetic vibration. It could be a crack or a loose brace. It also could be a loose screw on a tuner, the end pin inside the bass, etc. Buzzes like this are a real pain to track down. Get someone to touch all over the bass while you play. If they can touch something and stop the buzz you are on the right path. Good luck

 

[maphiles96]

I've had someone touch parts of the bass while playing and when touching the c bout it get's slightly more quiet, however when I press on the lower to mid part of the back it seems to vanish conpletely. The brace the luthier said might be coming loose is the top one though and touching around there doesn't change anything.
The bass has a piece of wood inlayed between the two halves of the back, could something have come loose there as well?

 

[dperrott]

Touching the bass and the buzz stops is not a reliable indicator. You are stopping the vibration that's causing the buzz, not stopping what is buzzing. Its probably an open seam, since its happening on the same note in different octaves. You can tap on the edges and find the open seam. Basses need upkeep. Could be a fixed crack that opened a bit and needs glue. Sounds like the flatback was rebuilt at some point. The back shrunk and a piece was added to widen the back. Its common. Could a cross rail be loose, yea. The winter is the time to deal with it. Take it to your luthier. Get a hygrometer and make sure the humidity level is around 30-35%.