Double Bass Shimming the bridge on EUB?

[GKon]

Hi everybody,

I play a Harley Benton EUB500 (European version of the Palatino).
Although I've had it and played it for over 1 year now, please keep in mind that this is still my first foray
into the world of any type of UB, hence my newbie question.

The stock bridge is adjustable and sits on a piezzo pickup. The profile of the bridge where the strings contact it is shaped in such a way that it is much higher on the E side and lower on the G side, when the adjusters are set equally.

In my getting to know the bass better I'm starting to experiment with the string heights.
At the moment, I've got the E string positioned 9mm high off the end of the fingerboard and the G at 6mm. The adjuster on the E side is fully closed (no adjustment) and the G side adjuster is showing about 2mm of gap.

I would like the G to have a height of 7mm/8mm but when I raised the G side adjuster enough to give me that clearance, the bridge looks very skewed and unstable and the volume dropped quite a bit on the G and D strings.

I'm not in a position to have a new bridge installed, so I was wondering if it is feasible to add a wooden shim to the bottom of the G side of the existing bridge, to help raise its initial profile, so that if using the adjuster and setting it at the 2mm it is now, it will give me the 7mm/8mm height I'm looking for.
Or, installing a shim that will raise it to the height I want without using the adjuster at all.

In looking at the bridge, it seems that if I install a shim it seems that the E side will then not sit flush on the piezzo pickup/body of the bass. But, when I use the adjuster, doesn't that logically skew the position of the bridge as well, but simply above the foot of the bridge?

So, is shimming one side of a bridge a realistic method of achieving what I'm after? If not, is there some other method to raise the G side of the bridge without over extending the adjuster, thus skewing the bridge and loosing volume?

Thanks, in advance, for your help.

P.S. The photo of the bridge is when I first unpacked it from the box, hence the ties holding the feet in place. It is not installed on the bass with the ties. Also, in the pic the bridge is shown with the E side to the right, G to the left. You can see the shape of the bridge with the E side being higher than the E.

 

[Francois Blais]

You could shim to see if it works.
Then maybe sand the feet in order to have the bridge standing straight?

 

[GKon]

You could shim to see if it works.
Then maybe sand the feet in order to have the bridge standing straight?

I know that I could play around with it, but, as I've never done anything like this before AND, if I screw up,
I don't have the financial ability to replace it if I screw up, I'm loathe to experiment too much right now.

I do appreciate the input, but am hoping for some more definitive info or even specifics if anyone has happened to
have done something similar.

 

[Francois Blais]

On the Palatino, it seems one of the mods was to put a piece of rubber tubing under the bridge.
(did you read the Palatino megathreads?)
Maybe put a piece on one side only?
You won't screw up anything experimenting with shims methinks.
That said, good luck with the experiment, those were my last comments in your thread.

 

[GKon]

On the Palatino, it seems one of the mods was to put a piece of rubber tubing under the bridge.
(did you read the Palatino megathreads?)
Maybe put a piece on one side only?
You won't screw up anything experimenting with shims methinks.
That said, good luck with the experiment, those were my last comments in your thread.

I did read the megathreads through before even purchasing the EUB. It was a great reference point for me.
And yes, I did install rubber tubing under the bridge and under only one foot

I'll see what I can come up with, shim wise. My concern was in sanding and cutting. That's what worried me.
I'll see if I can play around with it and make it work . Thanks for your time and input!

 

[DoubleMIDI]

The Bridge is intentionally higher on the E side. 6 to 9 or 7 to 10mm is a good setup for a DB and EUB. Get used to it.
Putting a shim on only one side is not a good idea, because what you want (equal height for all strings) does not work well with either a single shim or unequal adjuster heights. That way the bridge is no longer perpendicular, the bridge feet have a higher pressure on one side than the other (of one foot) and so you got a less good signal. Also the adjusters are harder to turn that way.
It's more an electro acoustic double bass than an upright bass guitar. If you want an upright bass guitar, look at the NED or Ergo stick basses on a tripod.

 

[GKon]

The Bridge is intentionally higher on the E side. 6 to 9 or 7 to 10mm is a good setup for a DB and EUB. Get used to it.
Putting a shim on only one side is not a good idea, because what you want (equal height for all strings) does not work well with either a single shim or unequal adjuster heights. That way the bridge is no longer perpendicular, the bridge feet have a higher pressure on one side than the other (of one foot) and so you got a less good signal. Also the adjusters are harder to turn that way.
It's more an electro acoustic double bass than an upright bass guitar. If you want an upright bass guitar, look at the NED or Ergo stick basses on a tripod.

Thanks for the info.

To be clear, I'm not looking for equal height to all strings.
I like the current 9mm height of the E, but would prefer the G be at 7mm as opposed to the 6mm it is now (6mm feels a bit too low for me), but at that height, the bridge gets all wonky and I loose volume a bit on the D and more on the G. hence my wondering if a shim would be a good idea.

Given the info you've mentioned regarding the not so good idea of a shim, I'll play with the adjuster on the G side and see how much more I can raise the
G string without loosing volume nor stability of the bridge.

Thanks again!

 

[Eric Hochberg]

You could take a mm off the E, A and D slot and see if that balances the heights better for you. Don't know if bridge strength would be compromised though...

 

[GKon]

Thanks for the tip.
Let's first see what I can accomplish with raising the adjuster just a tad.

 

[DoubleMIDI]

A single mm adjuster height difference is no problem, you don't need a shim for it and anyway the shim does the same as the adjuster does anyway. You might want to try 10 mm on the E, that's pretty much standard with a 7 mm G. If it is too high for you go back to 9 mm, no problem.

Sorry for the misunderstanding, but a lot of people coming from the bass guitar try to do the same to the EUB than what they do to their slabs.

 

[GKon]

A single mm adjuster height difference is no problem, you don't need a shim for it and anyway the shim does the same as the adjuster does anyway. You might want to try 10 mm on the E, that's pretty much standard with a 7 mm G. If it is too high for you go back to 9 mm, no problem.

Sorry for the misunderstanding, but a lot of people coming from the bass guitar try to do the same to the EUB than what they do to their slabs.

No worries, it's an honest misunderstanding, especially since I'm relatively new to the EUB.

If I do only raise the G to 7mm while keeping the E stock/unadjusted at 9mm, that's when it appears that there's too much
difference between the heights of the two sides of the bridge. It looks unstable. Now, this may only be a misconception on my
part. I do remember reading on one post here on TB, though, that you don't want too much difference between the two heights
of the adjusters (I don't remember the exact measurement, but I seem to remember that if I raise to 7mm while E is at 9mm, it
is too much).

Once I have some free time (next week?) I'll give it a try.

Thanks again.

 

[Francois Blais]

Maybe you could post a picture.

 

[GKon]

Maybe you could post a picture.

I definitely will. I'm just very busy with work this week and won't be able to get to it till next week.

Once I can do the adjustment, I'll take a pic of the bridge as is now, and another after I raise the G 1mm.
Then we shall see what's going on.

Thanks, to all, for their interest in helping me.

 

[DoubleMIDI]

If you raise only one adjuster, the top of the bridge and the adjusters lean to the other side, so the adjusters are no longer perpendicular to the body, the adjusters are hard to turn because they sit a bit angled in the thread nuts and the feet may raise on one side and push more on the other (on each of the two feet).
A single mm might work (or not), but it is probably at the border what is more or less healthy. If it gets harder to turn the adjusters, don't go further without raising the other one too.
Shims below the feet have the same function as the adjuster, so same shim thickness on both feet. The only solution would be to remove some wood from the G and D (and maybe A) at the bridge after going to 7 to 10 mm with the adjusters (or two shims of the same height). The shims might help if the adjusters get unstable otherwise better omit the shims.

 

[GKon]

If you raise only one adjuster, the top of the bridge and the adjusters lean to the other side, so the adjusters are no longer perpendicular to the body, the adjusters are hard to turn because they sit a bit angled in the thread nuts and the feet may raise on one side and push more on the other (on each of the two feet).
A single mm might work (or not), but it is probably at the border what is more or less healthy. If it gets harder to turn the adjusters, don't go further without raising the other one too.
Shims below the feet have the same function as the adjuster, so same shim thickness on both feet. The only solution would be to remove some wood from the G and D (and maybe A) at the bridge after going to 7 to 10 mm with the adjusters (or two shims of the same height). The shims might help if the adjusters get unstable otherwise better omit the shims.

Got it. Please note that, right now, it is set just that way. Meaning, the E side of the bridge has no adjustment, and the G side does. I took a moment and took a pic. Hope that helps.

Which leads me to another question I've had for a while now.

Whenever adjusting the bridge height, I've taken the tension off of the strings by detuning the bass, making the adjustment, then resetting the bridge and retuning the bass.
It seems next to impossible to adjust the height with the strings at tension.

Is this the usual/correct procedure? Is there a different or better way to do it?

 

[GKon]

 

[DoubleMIDI]

I think the down tuning before adjusting the bridge height was discussed in the setup & repair forum. Putting graphite powder on the thread may help, but it might depend on the thread. On my 5-string acoustic DB it is really hard to turn the adjusters, but I haven't used graphite powder yet.

 

[GKon]

I think the down tuning before adjusting the bridge height was discussed in the setup & repair forum. Putting graphite powder on the thread may help, but it might depend on the thread. On my 5-string acoustic DB it is really hard to turn the adjusters, but I haven't used graphite powder yet.

I'll take a look at the setup & repair forum, see if I can find the info I'm looking for.

Good tip about the graphite powder.