Double Bass Gut strings - Buzzing

[Jay Corwin]

I changed out my Spiracores for Eurosonic Lights so could play slap more and got serious buzz up by the nut on the E, A&D strings up to the 3rd note say G on E string & i seemed to have fixed it by jamming cardboard from a match pack between the string & nut, but it's no longer working & now getting worse buzzing.. It has got a bit colder here in SoCal , im Wondering if the bridge needs to be 'Scoshed' back towards neck a hair or some wood shims added to nut? These Eurosonics are supposed to be 'Gut Like' i haven't been able to afford the real deal yet! some day I'll put guts on Thnx! JP

Do you have bridge adjusters? You might need to raise your bridge height a bit to accommodate the lower tension strings. I wouldn't start shimming the nut if the previous strings didn't cause the same problem. In general terms, lower tension strings require a higher bridge height.

 

[DoubleMIDI]

The cardboard might have got compressed over time. Try two layers or a bit thicker cardboard. The cardboard could also get thinner by tuning because the windings shave off some paper dust.
You might want to use some plastic. I cut some plastic out of a yoghurt cup. It might help to rough up the underside to avoid slipping on the nut. You can also try a larger piece first and cut it down later when it got deformed to lay in the nut. Make sure that the front edge is aligned with the front of the nut or your positions move because of a different vibrating string length.
But the nut height only influences the open string (and how hard you have to press the string down close to the nut for fingered notes).

It might rather be that the fingerboard planing was done a bit sloppy and stopped to far away from the nut. Since the scraping is always towards the nut, it is often stopped sound inches in front of the nut. So it might be that additional planing is needed in this untouched area. At least that can explain why you got buzzes in that area.

And putting the string higher at the nut only influences the open string, not a fingered string, so the planing should be done first and then see if the open string still buzzes when the fingered ones do no longer.