nut height: is it too heigh

midiaxbill · Post by **midiaxbill** » Fri Jun 28, 2013 9:16 am

Hi. I built an upright 34" scale fretless bass. It has a maple neck, truss rod and a richlite fingerboard.
The nut is brass, Ive logged a months playing on it and Im very pleased with its sound, nickel roundwounds on a richlite fingerboard with a single humbucker give a good bright sound. Suprisingly the move from a horizontal fretless to an upright required no effort and took about an hour to get used to. The improvement in righthand (plucking) has been most welcome, Im a classical guitarist (MA 'performance') and have long righthand fingernails, these are a big handicap when playing horizontaly but when vertical, the nails are well away from the strings, no nail damage !

My reason foe this post is: I get loads of buzz in '1st position' (f on the E string). Its on all strings. I build classical guitars and give them about 1.5mm at the nut. I cut the nut at around the same height and now wonder if its height may be causing the buzz...
The nut is brass for earthing (its headless and I earth one machine head).

So what height would you go for?

(the neck is good and straight)

FretLessSince68 · Post by **FretLessSince68** » Fri Jun 28, 2013 2:34 pm

Your nut height is about right for a fretless instrument. I set mine even lower at around the thickness of a business card, approx. 1 mm with the larger strings having slightly more gap between the fingerboard and string.

You didn't mention how your neck relief is set and the action height as set at the bridge, so that is a good place to start.

If you have even the slightest back bow your strings will usually choke/buzz near the center of the fingerboard so I suspect that is not the cause of your problem but still possible. I have found that long wood necks are often not capable of extreme precision in straightness unless planed/surfaced under tension (tuned).

For optimal fretless action you want almost no relief at nearly straight, or even actually straight, fingerboard. The slightest imperfection in straightness or relief will show up as string noise and choking when you have the action set low.

So.... I suspect that your fingerboard may have a slight bump in the lower region about the 3rd position. Obtain a quality straight edge and observe the curvature (while tuned) using back lighting. Use short and long straight edges to observe various regions and localize any defects. If you find an area where the short straight edge "rocks" you have found a high spot.

Theoretically the fingerboard is supposed to be straight when the strings are removed and the tensioning rod loose. In practice this is often not the case. Additionally, when the instrument is tuned there is compression on the neck frequently causing small undulations or "S" curves to manifest. If this is the case then surfacing the fingerboard without tension may not solve the problem.

If you do have compression induced imperfections in the fingerboard/neck then you may have to make a rig to facilitate surfacing the neck under tension (tuned, including tension rod). Basically two dowels or blocks, one each positioned beyond the nut and over (or near) the bridge to jack the strings up high enough to plane or surface the fingerboard.

Let me know if this was helpful.

midiaxbill · Post by **midiaxbill** » Sat Jun 29, 2013 4:27 am

Hi, thanks for your reply.
I will have to try using a straight edge, the truss rod was about 1- 2 inches shorter than the fingerboard so there may be a bit of end curl (strange how difficult it is to find truss rods that are the correct length and price).

Ive never been happy with nut height on any of my fretless basses and tend to avoid 1st position (
ha).
On this instrument I cut the nut so it was heigh, closer to 2mm than 1, but I think an excessively high nut is just as likely to cause buzz as a low nut...
(would be nice to hear your thoughts on this)

I build classical guitar bodies from composites of carbon fiber and ciement fondu in geodetic frameworks that are then covered inside with carbon cloth. I must try buildng a fretless neck in a similar manner. the mixture of leight weight and stiffness would be very suitable.

FretLessSince68 · Post by **FretLessSince68** » Sat Jun 29, 2013 2:42 pm

Problems with notes choking, fretting out, buzzing, muted, or wolf tones, may be traced to any of four basic problems.

A defect in the neck or fingerboard.
Improper, maladjusted, or moving setup (most common).
Climatic changes.
Bad strings (rare).

A nut grooves set high should not cause problems by itself (except difficult to play), however if other portions of the setup are not done properly then it may seem as if the nut is a culprit. Check your relief and bridge height.

FretLessSince68 · Post by **FretLessSince68** » Sat Jun 29, 2013 2:44 pm

The most stable necks I have experienced are Modulus Graphite. Sounds great for fretless too.

midiaxbill · Post by **midiaxbill** » Tue Jul 09, 2013 4:58 am

Fixed it, I had the truss rod too tight, now Ive had to lower both the nut and the bridge. Plays well....

Starting to build an acoustic upright fretless bass now
:]