adjustable bridge

pippin · #1 01-18-2006, 09:19 AM

This is my first experience with an adjustable bridge on my new bass and I need a bit more space between my G string and the fingerboard. The other strings seem to have enough space to allow me to pick away. Does anyone want to offer any words of advise?

Chasarms · #2 01-18-2006, 09:48 AM

Quote:

Originally Posted by pippin

This is my first experience with an adjustable bridge on my new bass and I need a bit more space between my G string and the fingerboard. The other strings seem to have enough space to allow me to pick away. Does anyone want to offer any words of advise?

My only advice is to be very careful when raising or lowering the bridge to make sure that it doesn't get crooked. If you get one side higher than the other you can bind the adjusters and/or get the feet out of flush with the top.

Just make sure the amount of exposed threads on the adjusters is pretty much the same on both wheels. When you are raising the bridge, it is easier if you drop the string tension down a step or so. Not enough to allow the sound post to move, but enough to make the wheels turn a little easier.

If you need more air under the G, you may have to live with a little more air under the rest of the strings as well.

Also, before you mess with the height, double check that the bridge is aligned correctly along the vertical axis of the bass. If the bridge got bumped toward the E string side a bit, it would make the G string height seem a little low.

lowendforlife · #3 01-18-2006, 02:19 PM

Firstly, +1 on being EXTREMELY careful when adjusting your bridge in any way!

Quote:

Originally Posted by Chasarms

If you get one side higher than the other you can bind the adjusters and/or get the feet out of flush with the top.

Just make sure the amount of exposed threads on the adjusters is pretty much the same on both wheels.

I'm not sure I completely agree with that...on my bass, my teacher's bass, and many other professionaly set-up instruments that I've played, the G and E wheels are at different heights. I'm under the impression that the purpose of the adjustable bridge it to allow you to have different heights on each side, thus making for the most comfortable possible set up for your playing style. Equal thread exposure, imho, doesn't really matter. Feel free to correct me if i'm wrong, all, because it's entirely possible!

Humberto · #4 01-18-2006, 02:37 PM

I've always thought it was critical to have the wheels at the same height on both ends because it might place uneven pressure on the top, causing cracks or other problems.

I'm not a luthier, so I don't know this with certainty, but I would try to get the opinions of some of the guys here who build them and know best what to do.

Good luck.

pmckinney4 · #5 01-18-2006, 03:45 PM

I recently got my bass back from my luthier. While he had it he installed adjusters in my bridge. The way I got the bass back from him, they were set up at different heights. I am assuming since my luthier is the one that set them up like this, it is ok for them to be at different heights.

gomez hacienda · #6 01-18-2006, 04:56 PM

It IS OK to be at different heights. In fact I can't ever remember seeing adjusters that were the same. You always need a bit more air under the E side. If you couldn't stagger the adjusters, the bridge would have to be carved at the "perfect" angle to compensate. Kind of impossible if you wanted to try different strings.

gomez

Chasarms · #7 01-18-2006, 05:07 PM

Well think about it for a minute.

The process for installing adjusters is to drill a hole through the bottom of the bridge foot (x2). The bridge is then cut so the feet are separate from the main bridge. The feet are threaded and the adjusters are installed.

So, we know:

1. The hole is along one axis.
2. The shafts of the adjusters are straight.
3. There is only one vertical orientation of the bridge feet that is correct. That is, the full surface area of the bottom of the foot is in contact with the top.

Therefore, the main part of the bridge has to move up and down along a plane parallel to the axis of the holes/adjusters and the main bridge bottom has to stay parallel to the original plane of the cut that separated the feet. Otherwise there are really only three things that can happen.

1. The shafts have to bend
2. The holes have to enlarge
3. The feet tip on edge

None of those things sound healthy to me.

Maybe it doesn't matter, but there's no other way it can happen.

lowendforlife · #8 01-18-2006, 08:11 PM

Hmm...you make a good point. I definitley see and agree with the logic of your position, but it seems like there must be a catch. Maybe one of our esteemed luthier friends can shed a little light here.

Hector Wolff · #9 01-18-2006, 08:31 PM

Lowend...

Why must there be a catch?

It sounds like what you want is a bridge with individual adjusters for each string, just like on a BG. If so, they do exist, but I have no idea what effect the have on the sound of the bass, or how well they hold up. (I am not a luthier.)

The DB is not a bass guitar and (as I understand it) the bridge does not work the same way. The bass is usually set up with specific strings and playing style in mind. If the strings or playing style change then some changes to the set up, including the bridge and nut are likely to be required.

Now, if you are swapping out one set of steel strings for another, and the guages are similar, then it is possible that nothing needs to be changed. But if you wish to switch to a thick gut from a thin steel (or the reverse) you can expect to need the nut and bridge to be reworked.

As to the relative heights of the strings to the fingerboard, those proportions should have been properly worked into the nut and bridge by the luthier when the set up was done. If they have been then those proportions will usually remain relatively correct, though the entire nut and/or bridge may have to be raised or lowered.

Adjustable bridges were developed to allow for changes in action due to seasonal variation, change of playing style, change in type of string, none of which normally would require an unequal adjustment of the bridge.

arnoldschnitzer · #10 01-19-2006, 07:49 AM

Quote:

Originally Posted by pmckinney4

I recently got my bass back from my luthier. While he had it he installed adjusters in my bridge. The way I got the bass back from him, they were set up at different heights. I am assuming since my luthier is the one that set them up like this, it is ok for them to be at different heights.

Wrong. Your luthier botched the job. A bass should not leave a shop with a new bridge unless the individual string heights and arch are correct with the adjusters synchronized. The only exception is when a Realist pickup is installed; it may require about half a turn or so of compensation. Keep in mind that raising one leg of an adjustable bridge will only move the bridge sideways, and may actually lower that side, as you are driving the strings into the arch of the fingerboard.

mchildree · #11 01-19-2006, 08:43 AM

I guess this illustrates, once again, something that is valuable for DB newcomers to remember: Be very, very careful of what you read on the internet. There are lots of people around who are all-too-ready to make definitive (to them) statements that are incorrect and could cause you to harm your instrument or yourself if taken literally. Luckily, we have many experienced players and luthiers among us here on TB, so make sure you're getting good advice from someone like Arnold before mucking about with your bass....

bassist14 · #12 01-19-2006, 08:50 AM

hello,

i am using the mpm (from mr. moser in austria) adjusters wich allow to set individual height of both legs of the bridge.

you can see pictures here:
http://www.moser-klangwerkstatt.com/...produkt1.shtml
and here:
MPM adjuster Full Circle combo

additional info here:
Titanovation Titanium adjusters

bassist14

lowendforlife · #13 01-19-2006, 01:16 PM

Thanks for the clarification, Arnold!
Unfortunately, I guess my luthier botched the job too...even though I have a Realist on my bass, the adjusters are FAR from just a half-turn apart. My string height is extremely comfortable now...I guess i'll have some measuring to do before I get some adjustments made...::sigh::

pmckinney4 · #14 01-23-2006, 04:18 PM

Quote:

Originally Posted by arnoldschnitzer

Wrong. Your luthier botched the job. A bass should not leave a shop with a new bridge unless the individual string heights and arch are correct with the adjusters synchronized. The only exception is when a Realist pickup is installed; it may require about half a turn or so of compensation. Keep in mind that raising one leg of an adjustable bridge will only move the bridge sideways, and may actually lower that side, as you are driving the strings into the arch of the fingerboard.

Hi,

Thanks for your post. After seeing it I checked the setup of my bridge again. I was mistaken, they adjusters on my bridge just appeared to be out of sync due to the way the wood of the bridge was cut when they where installed. It is kind of an optical illusion. I thought they were at different heights because there is more of one of the screws on the adjusters showing than the other. But they were installed that way to level out the bridge and they are vertically lined up as to not skew the bridge to the left or right. Sorry for any confusion that I may have caused by my earlier post.