Double bass strings/setup???

[Ewan Dumbleton]

Hi folks
I have a 4-string double bass set up for orchestral playing. My bass seems noticeably different to others I’ve played in terms of moving between strings in the same hand position. So - I’ve done some measurements on my bass by temporarily laying paper tape across the fingerboard under the strings and marking the tape with the stop position of correctly stopped notes in various positions, using an electronic tuner. The positions marked thus form an imaginary fret, which consists of a series of very obvious steps across the fingerboard – hardly a straight line at 90 deg.


The bridge is correctly centered, with it and the nut at 90deg to the fingerboard. String length is a uniform 1043mm for all strings.


As an indication of the discrepancy, comparing E and G strings:

• · For Ab just above the nut on the G string, the in-tune position is 6mm closer to the bridge than the F position on the E string.

• · B on the G string is 7mm closer to the bridge than the G# on the E string

• · D on the G string is 10mm closer to the bridge than B on the E string

• · The G octave on the G string is 10mm closer to the bridge than the E octave on the E string.

OK, I expect some difference in imaginary fret position across the fingerboard on a double bass because of the large change of string thickness/stiffness from E to G strings, but this much?


Is this amount of discrepancy across the fingerboard normal? Is it a symptom of poor quality, poorly matched, or old strings? Could there be something else wrong with the bass setup that’s not visually obvious?


I’ve no idea what strings are on it. From the similarity of the felting at the ball ends, they appear to have started life as a matched set. All appear to be flat wound on a solid synthetic core. String diameters are 2.88mm, 2.27mm, 1.75mm and 1.25mm. Strings are OK for playing, except that the G string is very sensitive to bow position and angle, and can rapidly develop a case of the scratchies.

[Ken Smith]

Ok, nut height and bridge height and fingerboard curve might be the issue. I can't tell you exact measurements but pics would help.

[Ewan Dumbleton]

Thanks for the response, Ken.
I’ve uploaded a couple of photos of the bridge and nut areas.


Stop positions
Here are the measurements of stop positions. The measurements are along the string from the flat face of the bridge facing the fingerboard. Bridge thickness at the string seats on the bridge is about 5mm.


Bridge to nut measurement is 1043mm for all strings

• Octave position: 533mm on E string; 524mm on G string.

• Fifth position: 709mm at B on E string; 699mm at D on G string.

• Major third position: 836mm at D# on B string, 831mm at B on G string.

• Semitone position: 995mm at F on E string, 989mm at Bb on A string, 991mm at Eb on D string, 986mm at Ab on G string. (ie, rather uneven across the fingerboard) (see photo).

Apart from the semitone position, the stop positions are stepped reasonably regularly across the fingerboard.


String clearance (as a proxy for fingerboard scalloping)
(Measurements with no string stopping)

• End of fingerboard: G: 5.0mm, D: 6.6mm, A: 7.3mm, E: 7.4mm

• Octave position: G: 5.9mm, D: 7.1mm, A: 7.2mm, E: 7.0mm

• Fifth position: G: 5.9mm, D: 7.2mm, A: 7.1mm, E: 7.0mm

• Major third position: G:5.2mm, D: 5.6mm, A:5.7mm, A: 5.6mm

• Semitone position: All about 2mm

No buzzing, except from the E string against the end of the fingerboard when stopped in high position and bowed hard far too close to the end of the fingerboard.


Rgds



Fingerboard curvature (across the fingerboard)
Hard to measure and define with the strings in place. However, I could do measurements from a straight edge above the strings??

[Ken Smith]

No way to judge this on line.. Would have to see the bass. Find a good bass luthier there. Ask the players in the local professional symphony. They will know and get a teacher. No way to learn on your own with a DB.. It;s torture.

[Ewan Dumbleton]

Common professional advice since has been that the strings must be at least 7 years old, are rather stiff and not very good- - - Therefore, get them replaced, play it a while, then get the setup optimised.


Thanks for your help, Ken