Double Bass Neck relief on EUBs

[Jonny Cumbo]

Hi,
I'm trying to find out what the relief should be on an upright bass neck. I am a luthier and have been given an electric upright bass which seems to have a massive relief on on it so that the strings in the middle have an uncomfortably high action. As this instrument does not have a truss rod (as with all acoustic uprights) the relief was originally carved out. It is possible to tilt the neck but this still leaves a large discrepancy in action from nut to middle and from middle to body end.
When looking down the neck of conventional double basses i have never seen as much relief as there is on this Azola.

 

[james condino]

Is it a relief issue or has the end of the fingerboard that is not attached to the neck warped up towards the strings? A general starting point for relief on an acoustic double bass would be half the string diameter. It will vary across the individual strings; roughly 1.5mm on the E string and less as you work towards the G, IF the fingerboard is reasonably straight and we are talking about steel or steel type modern strings. It may be up to twice that for gut strings.

Do you have the Henry Strobel book, "Useful Measurements for Violin Makers" on violin family setup specs? It may well be the best $12 you'll spend your entire career. Henry was a gem of a man who ran a wonderful old school violin shop out in the country outside of Salem when I lived in Oregon. He constantly published all kinds of books and information sharing his knowledge with other aspiring builders.

Book List

 

[DoubleMIDI]

For me it looks like that the bridge curvature was too less for the player and the fingerboard was reshape do for a higher curvature but that was not done completely leaving the upper part close to the nut as it was.
I think if the fingerboard including the nut would have been reshaped completely your problem would not be there.

Put a something completely straight in parallel to the underside of the fingerboard to find out if the fingerboard has been warped, but I doubt that it is warped.

It seems that you are not a DB luthier. Truss rods on EUBs are mostly non-functional because th nick is too thick. If you are not used to reshape a fingerboard on non-fretted instruments better take it to a DB luthier who has experience with that sort of stuff.