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Double Bass Uncentered bridge

A

aaronallen

Jan 6, 2007
140
6
Austin, Texas
#1
Hi, hoping someone can help me decide what to do about my somewhat ill-fitted bridge.

I bought an old bass about a year ago and had some repair work done including a new bridge with adjusters. In hindsight, I really wish I had given detailed instructions about how I wanted the bridge made. Instead I just left it up to the luthier thinking he's probably done this hundreds of times, there shouldn't be any issues. Well, there are several problems with it and now I'm wondering if anything can be done or if I should just spring for a new bridge (again).

The main problem with this bridge is that the strings are not centered with respect to the top of the bridge. This means that for the strings to be centered over the fingerboard, the bridge will not be centered on the body (pushed towards the treble side by a little over 3mm). The E bridge foot is then not straddling the bass bar the way it ought to. I think this is partly why I'm not getting quite as much 'oomph' from this bass as i'd like. From the look of the top, this is how bridges have historically been positioned on this bass, so my luthier was just following in these 'footprints' when he made the new one even though its clearly incorrect.

How feasible is it to replace the top half of an adjustable bridge? I'm thinking this would be the most economical solution. Or Should I just have a whole new bridge made? Should I even expect much of an improvement in sound from a properly centered bridge?

Thanks for your insights.
 
#2
Doubtless more experienced people will chime in, but my first inclination would be to check that the centerline of the neck/fingerboard lines up with the centerline of the body-there may be a misalignment that the luthier didn't take into account. I don't know if moving the bridge toward the bass side 1.5mm will make much of a tonal difference. Is there a reason you couldn't trim down the existing bridge to get rid of the string grooves, then put new slots where it suits you?
 
#3
You could have the bridge recut. This will cause your adjusters to be extended further than they are now. You might also need shims added to the legs to compensate. Replacing just the top half of the bridge would be much more challenging than replacing the bridge in its entirety.
 
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#5
Here's some photos. The ones with the string and washer show how far off the string notches are. I'm thinking if the notches were moved about 3mm towards the treble side then they'd be about centered on the bridge and then the bridge could be correctly positioned on the top.
Due to the steep contour under the G, recutting the bridge top and then moving the bridge towards the E side would require the adjusters to be pretty far out. I guess if its acceptable to then add some wood to the legs under the adjusters, then that would be the easiest solution.
 

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#6
It would be pretty easy to re-arch the bridge to remove the current slots and then re-cut the slots. You'd lose less than 1/8" and that shouldn't stress the adjusters or the legs.

I think you'd be better off tonally with a completely different bridge. That one's tall, thick, stiff waist section is really keeping the bass from making strong lower frequencies. And to me, if your guy doesn't know about the tonal properties of bridges, how's he going to do with the sound post?

Just one man's opinion. YMMV
 
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#8
I think the strings are to close together, there is a lot of fingerboard left of th g and right of the E. Therefor the top of the bridge was more curved. Stretching the string spacing may get you problems on the G side, because the bridge height falls down quickly over there. You may need to take a lot off the bridge, mainly in the middle at D and A, but you cannot get wood back at the G, so you need to put wood off from E to D and raise the adjusters.

I have the impression, that the strings are 1.5 to 2 mm off. If the difference is 3 mm, moving by 1.5 mm puts it in the middle.

It seems like the bridge could be moved 1.5 mm towards the bass bar side. Then the E might have a good position relative to the fingerboard and you can move the slot of the A 1 mm, the slot of the D 2 mm and the slot of the G 3 mm towards the soundpost side and reduce the curvature of the bridge a bit.

But if you don't know of understand why better don't do it yourself. OTOH, the bridge is already treated badly by removing too much wood from the G side, so you might need a new one anyway. But bring your bass to a good bass luthier this time!
 
#9
Jake deVilliers said:
I think you'd be better off tonally with a completely different bridge.
Click to expand...

Jake, thanks for your comments!
What sort of bridge would you recommend? Could you post a pic for reference?

This bass has the overall tonal character that I want, I just feel like it can be a little thin sounding, not in a nasal/overly bright way, just lacking some of those cushion-y sub-bass frequencies.
I'm also curious how it would sound with a different sound post. The current post is thin, about 5/8'' diameter and looks to be 30+ years old. From what I've read, a fatter post will likely get me closer to the sound I'm after.

I guess the biggest obstacle I'm facing is that there aren't any luthiers in my area (AFAIK) that I trust wholeheartedly, at least not with the detail oriented stuff like shaping a bridge or fitting a post.
 
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#10
I am not a DB player so feel free to ignore, but do have some experience with the cello.

IME with cello, a snug, 'acoustically-coupled' fit between the feet of the bridge and the top, the position of the sound-post relative to the treble foot and the actual fit of the sound-post against the inside of the top and back are more important than the alignment of the strings over the bridge - string spacing and bridge radius really only impact playability. From your pictures, and it could just be the camera angle, I think the tailpiece looks quite narrow which suggests it might also be quite small/light. In cello speak, a too-light tailpiece is often cited as leading to reduced low-end response. Also, if the string spacing on the tail piece is too narrow the clamping force from the E/G strings will not act directly down through the bridge - this might affect tone if you are not getting the best acoustic coupling between the bridge and the top.

Like I said, this is from my limited experience with cello so it could all be complete bunkum, but it seems to me that cello and DB are similar in many ways so some knowledge might be transferrable - who knows?
 
#13
aaronallen said:
Jake, thanks for your comments!
What sort of bridge would you recommend? Could you post a pic for reference?

This bass has the overall tonal character that I want, I just feel like it can be a little thin sounding, not in a nasal/overly bright way, just lacking some of those cushion-y sub-bass frequencies.
I'm also curious how it would sound with a different sound post. The current post is thin, about 5/8'' diameter and looks to be 30+ years old. From what I've read, a fatter post will likely get me closer to the sound I'm after.

I guess the biggest obstacle I'm facing is that there aren't any luthiers in my area (AFAIK) that I trust wholeheartedly, at least not with the detail oriented stuff like shaping a bridge or fitting a post.
Click to expand...
You haven't told us a thing about the bass.
 
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#14
Its a 3/4 fully carved bass made in 1930 by E H Roth. Bridge height is 6". 41.25'' string length. Spiro weich strings.

I doubt the fingerboard is perfectly centered and I used to think that was why the bridge needed to be off, but that doesn't explain why the string slots should be uncentered. The way this bridge is fitted completely disregards the bass bar. Its needs to be moved 3.2mm to be in the optimal position and with slots placed correctly, everything should be more or less lined up.
 
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#15
aaronallen said:
Its a 3/4 fully carved bass made in 1930 by E H Roth. Bridge height is 6". 41.25'' string length. Spiro weich strings.

I doubt the fingerboard is perfectly centered and I used to think that was why the bridge needed to be off, but that doesn't explain why the string slots should be uncentered. The way this bridge is fitted completely disregards the bass bar. Its needs to be moved 3.2mm to be in the optimal position and with slots placed correctly, everything should be more or less lined up.
Click to expand...
You've given your own answer - find a better bass luthier, it will be cheaper in the long run! :thumbsup:
 

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