Double Bass Strange buzz on open G

[Chansey]

Hi everyone,

I have a strange buzz on my open G string which is coming from the scroll/nut area. It is really mild (pretty much inaudible except from playing position) but is driving me nuts because I just can't seem to pinpoint where it is coming from. I have tried methods such as tightening the tuning machines, shimming the nut slots etc but nothing seems to work. What works however, is quite strange:

1) Temperature: the buzz reduces in volume at warmer temperatures

2) Detuning other strings: strangely enough, the buzz disappears completely if I take tension off any of the other strings. Once playing tension is restored, the buzz comes back.

3) Applying light pressure anywhere in the scroll area (on any tuning machine peg, directly on the scroll etc). Pretty sure I'm just muting the bass here.

4) Even changing the endpin height has some impact on the buzz (lower heights seem to reduce it)

Anyone has experienced this before? I'm starting to suspect that it's not really a mechanical buzz, but maybe due to resonant frequencies/wolf note etc? I find it hard to pinpoint the buzz to others as it's pretty soft but it's definitely there.

Thanks!

 

[Jake deVilliers]

Maybe one of the strings is sitting lightly on another shaft in the peg box.

 

[David Jayne]

+1 Jake or, maybe one of the cut string ends is touching the side of the peg box?

 

[Greg Clinkingbeard]

I suspect the nut slot isn't cut right. The string should make contact at the end of the fingerboard. Loosen the string and look at it.

 

[Jake deVilliers]

The string should make contact at the end of the fingerboard.

Really?

 

[jmpiwonka]

i'm guess it's a typo...

 

[Greg Clinkingbeard]

No, it's not a typo. I was too busy to properly explain it. What I mean is that the nut slot should be filed so that it slopes down into the pegbox. If it is more or less parallel with the fingerboard right where the nut and fingerboard meet, the open string can buzz. A metal wound string will leave a silvery shiny mark in the slot, showing the contact point.

 

[Chansey]

Thanks for the responses! So far, I am not seeing excess string lengths in the peg box and also there is no unwanted contact between strings. The point about the nut slot is something new to me though, can't wrap my head over how it works. I should check it out later

 

[bassfacer22]

Put a piece of small torn paper under the string in the nut slot and then tune up your string making sure the paper is raising the string slightly in the nut.. Then see if you still hear buzz.. It's got to be the nut.. Which in that case a luthier will have to fix that properly..

 

[DoubleMIDI]

The piece of paper won't help unless it raises the string at the fingerboard side of the nut only, so no wider than two millimeters.
A piece of rubber in the nut groove between nut and string, parallel to the string might help a bit, at least temporarily. But it can still buzz a bit.