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Double Bass Altering string height at home

punkjazzben

punkjazzben

Jun 26, 2008
1,711
206
Australia
#1
Hi all,

I have a Gliga bass from 2006 that was set up in Melbourne by a professional luthier, Ben Puglisi, and who has done a few check-ups for me in the years after I bought it. I'm now living 5 hours from Puglisi, who is the nearest luthier anyway. I haven't the time, money, or transport to get to Melbourne with my bass, but I need to lower my strings.

The bass has Corelli 370TXs on it at the moment, which after much experimentation I have settled on (again). I just measured string height at the end of the fingerboard (round not bevelled) and it's about 11mm on the E and 8mm on the G. At the nut things look as they should - about a business card thickness.

I would like to lower the height by perhaps 2.5-3mm; the end goal is to make things much easier on my left hand.

Now, I've seen a luthier remove the strings, being careful to not let the soundpost slip, and place a piece of sandpaper on the body of the bass while running the bridge feet over the sandpaper - presumably to keep the right curvature - in order to lower the string height.

Is this something that can be relatively safely done at home? (i.e. without completing wrecking the bridge) If so, how much should be shaved off the feet to achieve roughly 3mm off the string height?

Cheers,
Ben
 
#4
Did your string height ever feel comfortable to you at some point? I only ask because your current string height seems much higher than standard. How does your bridge look from the side? Is it is nice and straight and not leaning towards the fingerboard?
 
#5
JoeyNaeger said:
Did your string height ever feel comfortable to you at some point? I only ask because your current string height seems much higher than standard. How does your bridge look from the side? Is it is nice and straight and not leaning towards the fingerboard?
Click to expand...

Checked out the bridge and it's nice and straight, and the center of each foot is aligned with the notch in the f-hole on either side.

As far as I understand, the height of the strings has something to do with Rabbath. My teacher was one of his students in the mid-90s, and she helped me pick the bass back in 2006 and gave the luthier instructions regarding setup and strings. When I was playing 4-5 hours a day during my music degree, I had a bit more strength but it never felt entirely comfortable, if I'm to be honest. It was one of those naive "well, if the teacher thinks it's fine it must be" kind of situations.

EDIT: Just had a look at my Rabbath book, and he mentions keeping the strings low. So either 'low' is very relative, or something else has happened to my bass that will probably need a luthier. Dang.
 
#7
Low is very relative, and 11-8mm sounds about right for low-tension strings like Corellis.

If you must go lower, definitely lower string height from the crown of the bridge and not the feet, assuming you have enough wood left at the crown. A pic would be helpful.

What I do is loosen each string and use a hobby file to make the string slot deeper until I have it where I want it, re-tuning the string and checking the string height often.

When the strings are at the desired height, I remove the bridge and use a belt sander to remove the excess wood from the bridge crown and re-profile the face of the bridge accordingly.

You sound unsure, so proceed with caution. If you botch the job, the bridge will probably be toast, which means you'll be making the trip to the luthier anyway.
 
#8
Okay, I had gotten the impression that your setup at one point was 'good' and now it wasn't. Like Andrew says, I would still want to verify that nothing else is going on such as the fingerboard being partially unglued. Are you close to Sydney at all? Matthew Tucker is in Sydney if that is at all more convenient.
 
#9
It's best to have at least 30mm above the heart in the center of the bridge to the top of the bridge. If a bridge has 30mm or less, the height can be lowered by taking it from the leg above the adjusters (assuming I'm working with an adjustable bridge). Before working in a shop with professionals who have worked with many, many hundreds of bridges I ruined a few. Proceed with caution.
 
#10
Greg Clinkingbeard said:
It's best to have at least 30mm above the heart in the center of the bridge to the top of the bridge. If a bridge has 30mm or less, the height can be lowered by taking it from the leg above the adjusters (assuming I'm working with an adjustable bridge). Before working in a shop with professionals who have worked with many, many hundreds of bridges I ruined a few. Proceed with caution.
Click to expand...

If the OP had an adjustable bridge, I don't think he would be having the problems he has stated unless he ran out of room on the adjusters. If he does have to make the trip to a luthier, it may be worthwhile having adjusters fit.

A question for the OP, how much seasonal temperature and humidity change do you get? weather changes can account for a fair amount of change in your action.
 
#11
Andrew McGregor said:
What's the string height at the octave? That will tell if it's neck movement; if the neck has bent forward, the height at the octave will be about the same as at the end of the fingerboard.
Click to expand...

Just measured at the octave, and the height is about 1mm less than at the end of the fingerboard (across all strings).

RSBBass said:
If the OP had an adjustable bridge, I don't think he would be having the problems he has stated unless he ran out of room on the adjusters. If he does have to make the trip to a luthier, it may be worthwhile having adjusters fit.
Click to expand...

Correct, and I wish I had them fitted originally now!

RSBBass said:
A question for the OP, how much seasonal temperature and humidity change do you get? weather changes can account for a fair amount of change in your action.
Click to expand...

Averages over the years for the town I'm in - January: 12°C min, 26°C max, relative humidity 60%; July: 4°C min, 12°C max, relative humidity 87%. There isn't as much seasonal variation as other parts of the world, and certainly not the extremes.

This could either be a case of a simple adjustment to the bridge to lower the strings to my own preferences, or there might be other issues if 8-11mm is considered higher than standard (or at least higher than an experience luthier would set it) - though someone mentioned the Corellis being a factor there. Either way, I'm starting to thinking it'll just be easier to make the trip somehow, and potentially cheaper if I stuff the bridge accidentally.

Crazy thought from someone with obviously very little knowledge of luthiery - ignoring any compounding issues with the bass itself, what's the viability of posting the bridge off for adjustment?
 
#12
Trimming a bridge remotely could be done. The trick is to to take precise measurements of the string height at the end of the fingerboard. For this I would recommend slipping a small piece of plasticine at that point and get a good impression of the string and fingerboard. Then carefully remove the plasticine and using a precise rule or digital calipers get a reading. Do this under full tension with bridge set at the proper angle.

It's not the preferred method. Not having the actual bass on site makes it difficult to tweak the fitting. But I think it could be done.
 
#14
punkjazzben said:
What's the viability of posting the bridge off for adjustment?
Click to expand...

If your relative string heights are appropriate, it would be relatively easy to send the bridge out and have adjusters installed.

I've done this a couple of times and its worked out well.
 

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