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Bridge Height correction

Discussion in 'Setup & Repair [DB]' started by eh_train, Dec 22, 2005.


  1. eh_train

    eh_train Supporting Member

    Jan 12, 2004
    Toronto
    Hi all

    I'm considering buying an older 3/4 czech ply bass which might serve as a workhorse for some blues gigs... It's cheap and unattractice enough that I would like to do some adjustments myself. Right now, the bridge height is 6" at its highest and the strings are set fairly high. If I simply lower the bridge to get the strings where I want them the bridge will probably end up at 5.5." I know this isn't recommended, and that closer to a 7" bridge height is typical.

    My question is, how bad is it to have such a low bridge? (I mean sound-wise and future health-wise). By the way, the fingerboard is coming unglued so I could consider putting in a shim to change the neck angle. The neck joint doesn't seem stressed so I'd rather not reset the neck. Are there previous posts describing how to install a shim to change the neck angle?

    Any help is greatly appreciated!
     
  2. There's no rule book for the the height of the bridge. It's a meaningless number. What matters is the distance between the fingerboard and the string.
    As for neck and fingerboard repairs, my impression is that you underestimate the difficulty of a proper job.
     
  3. KSB - Ken Smith

    KSB - Ken Smith Banned Commercial User

    Mar 1, 2002
    Perkasie, PA USA
    Owner: Ken Smith Basses, Ltd.
    Two things are needed for playing comfort. 1) to be able to bow the G and E strings without touching the C bouts of the Bass with the Bow hairs.. and 2) playing up in thumb position easily without any major problems with normal technique.

    Fixes are 1) proper neck stand and moving the neck out a bit and/or 2) the picth angle of the neck to the top, and 3) the Bridge height to match the correct neck.

    I think 6" is ok for a String height if you can press the strings down from the Nut to the end of the FB. 7" is on the tall side and 5.5" is on the low side. If you can play it as-is, save your money for now.
     
  4. eh_train

    eh_train Supporting Member

    Jan 12, 2004
    Toronto
    Thanks for the replies. I will likely get the bass and use it for a while before deciding whether the neck angle/ bridge height needs to be increased....

    Don, I don't think bridge height is a "meaningless number." As Ken points out, being able to bow is a consideration. I checked "overstand" in the repair thread and many TBers feel that the combined neck angle/bridge height has a large effect on projection, playability, etc...

    Also, and I hope I'm not being churlish here, I don't know why you would assume that I "underestimate the difficulty of a proper job". As I explained at the beginning of my post, the bass is a beat-up inexpensive plywood. IMO, it doesn't warrant top-flight repairs for what will, at best, be an adequate plywood instrument. I have already repaired several of this type of instrument (reglued and re-attached broken scrolls, reset necks, reglued loose fingerboards). I was surprised that the assumption seemed to be that I was uninformed.

    I highly value the advice on TB, and have already learned a lot from it. If I go ahead with this project, I'm sure to have further questions!

    Thanks,
    Paul (eh_train)
     
  5. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    One could have a bass with a 7" bridge height and a 4mm overstand. This would be undesirable. Conversely, the overstand could be 38mm and the bridge height could be 5". In your particular case of this "beater" bass, lowering the bridge height for optimum right-hand playability is more important on what the bridge height happens to be. As for bowing, a tighter radius on the crown of the bridge would be a big help.

    But, if your current bridge blank has very little wood over the heart, you may need to use a smaller blank on this plywood. Can you post some pics of your bridge?
     
  6. eh_train

    eh_train Supporting Member

    Jan 12, 2004
    Toronto
    Thanks for the further help!

    [/QUOTE]But, if your current bridge blank has very little wood over the heart, you may need to use a smaller blank on this plywood. Can you post some pics of your bridge?

    I don't have pics because I'm not the owner - yet. I will go and see it again and try to get pics... The bridge looks small, and I'm not sure how much wood is above the heart. In any case, the bridge is completely warped and will need replacement...


     
  7. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    Crown= top of the bridge.
    Tighter radius= more curvature... easy bowing.
    Flatter radius= less curvature... easy pizz.
    The string spacing can stay the same... this crown radius is also dependant upon the fingerboard radius.
     
  8. eh_train

    eh_train Supporting Member

    Jan 12, 2004
    Toronto
    Nick

    Thanks for the clarification.

    I have looked at the bass again, and am now concerned about whether the neck has bowed with the string tension. I mentioned previously that the fingerboard is loose (but just at the nut end), and it does seem that the maple is a little bowed between half and second position. I realize that regluing the ebony MIGHT help straighten the neck, but I have asked the seller to go with me to the Sound POst (local repair shop) for a more expert opinion.

    If I end up getting it, I'll post pics...

    Thanks again,
    Paul
     
  9. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    It's good to hear that you are taking the bass in for a second opinion by a luthier... more people should do this when buying from a private party...
     
  10. droo

    droo

    Nov 1, 2004
    Oxfordshire, UK
    Perhaps another thing to examine is the position of the bass bar and its distance to the centre line - my cheap hybrid bass also had to have a low bridge height (around 5") to get a playable string height, but also the position of the bass bar was such that a 1/2-size blank seemed more suitable anyway.
    (Just a suggestion based on my experience, not luthiery skill!)
     
  11. glivanos

    glivanos Supporting Member

    Jun 24, 2005
    Philadelphia Area
    Wouldn't the neck fingerboard radius dictate the bridge raduis?

    Otherwise string heights would be different for each string off the fingerboard.

    Yes/no??:confused:
     
  12. bpclark

    bpclark

    Apr 30, 2003
    West Central, OH
    Depends on what the fingerboard radius is. My Kay is mostly flat and if the bridge were to match that then bowing the middle strings would be near impossible. Especially in thumb position because when the string is depressed it's dips below the level of the strings on either side.
     
  13. KSB - Ken Smith

    KSB - Ken Smith Banned Commercial User

    Mar 1, 2002
    Perkasie, PA USA
    Owner: Ken Smith Basses, Ltd.
    The Bridge MUST be cut for maximum bowing capability. If the Fingerboard is too flat, then get a new one. You can't match a Bridge to a bad FB.
     
  14. bpclark

    bpclark

    Apr 30, 2003
    West Central, OH
    Well, they're reshaping the fingerboard to the extent that it can be now. The bridge that's on it was cut with more curve than the fingerboard and it bowed OK for most things, but I had to be extra careful at times. If they can get just a bit more arch for me, I think it will be OK.

     
  15. I actually got to "cheat" as my luthier put it. We ended up putting a thin piece of maple under the left foot of my bridge to raise it up. It works though, no more buzzing in second position!