Double Bass Vibration from A string

[martinc]

I have a vibration coming from my A string (Spiro Weich).
I have tried three different Weich A strings but the vibration is still there. It only happens when I play the A string open. No problem when the string is noted.
It sounds like it is coming from the bridge/tailpiece area. I have also:
- checked the tailpiece and endpin for looseness
- adjusted the tailpiece length twice.
- cleaned out and re-filed the bridge and nut grooves
- added a piece of leather to where the aircraft cable is attached to the Wittmer tailpiece as per Arnold's suggestion a few years ago
-checked the tuning gears and small retaining screws on the tuners plates for looseness/vibrations
- checked inside the bass with a mechanics mirror for cracks
- pressed the top in different locations to see if the vibration stops.
So far no luck with anything. No problem with the other strings.
Any suggestions would be appreciated.

 

[Matthew Tucker]

Does it happen when you play the same A on the E string?

If it does, then it's probably something to do with something resonating with that note. If it doesn't, then it is probably still that string.

Try a piece of thin cardboard in the nut slot - any change?
Pull the endpin all the way out and tighten it -any change?

 

[punkjazzben]

Try pressing the A string behind the nut or on top and play it open. If it stops vibrating, then I'd say it could have something to do with the angle your A string is leaving the nut; if it's not a sharp enough angle as the string heads toward the tuning post, it can vibrate at the nut.

That's my only suggestion, otherwise my guess is as good as yours!

 

[martinc]

Does it happen when you play the same A on the E string?

If it does, then it's probably something to do with something resonating with that note. If it doesn't, then it is probably still that string.

Try a piece of thin cardboard in the nut slot - any change?
Pull the endpin all the way out and tighten it -any change?

Matthew: Thanks for the reply.
I have already tried the thin cardboad in the nut slot but the vibration is still there. Also the endpin tightening etc. No change.
The open string note sounds fine initially but I hear the vibration noise during the decay time. In addition to the three Spiro Weichs I also tried a new Helicore Pizz medium A and Jazzer A. In both cases the "vibration" was worse than the Spiro Weich.

took your suggestion and tried the A on the E string and it does the same thing.......vibrates more loudly than the open A! But it is fine with the A on the G D strings.
Do you think the "vibration" a "super wolf" tone? Any solution? I have also changed the distance of the tailpiece from the bridge by adjusting the length of the aitrcraft cable.

Have you heard of anyone else with a Wittmer tailpiece that had this problem?

A late edit....I did some work on the angle of the A string and the E string where the string came into the nut groove on the peg head side. That helped a bit. I have also built up the bottom of the A string nut groove on the fingerboard side. Looks a little close to the fingerboard to me. We'll see. I'll let you know later when I have re-done the A string groove.

 

[martinc]

Try pressing the A string behind the nut or on top and play it open. If it stops vibrating, then I'd say it could have something to do with the angle your A string is leaving the nut; if it's not a sharp enough angle as the string heads toward the tuning post, it can vibrate at the nut.

That's my only suggestion, otherwise my guess is as good as yours!

Ben: Thanks for the reply.

I filed the angle of the nut slot to make it a little sharper as per your suggestion and it helped a bit.
However when I was doing this I noticed the bottom of the groove on the fingerboard side looks a little too close. I just finished building it up very slightly with some ebony dust and super glue.
I'll let you know if it makes any difference.
I have been reluctant to mess with the nut slots because I just had work done on the bass and the nut slots were re-done.
I made the angle for the E string a little sharper too.
I'll report later today when I have re-done the bottom of the nut groove.

 

[martinc]

Matthew and Ben from Oz:

I built up the A string nut groove where it meets the fingerboard and it has solved the vibration problem.
The Weichs have lots of "spring" and it appears the vibration came from contact with the fingerboard at that location. I changed the angle of the E string nut slot too and I no longer have vibration when play an A.
I have a recording session to do later today. The vibration would have been a real problem if I had not been able to get rid of it.
Thanks for the suggestions you provided!

 

[punkjazzben]

Matthew and Ben from Oz:

I built up the A string nut groove where it meets the fingerboard and it has solved the vibration problem.
The Weichs have lots of "spring" and it appears the vibration came from contact with the fingerboard at that location. I changed the angle of the E string nut slot too and I no longer have vibration when play an A.
I have a recording session to do later today. The vibration would have been a real problem if I had not been able to get rid of it.
Thanks for the suggestions you provided!

Great hear the problem has been solved!