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4/4 bridge on 3/4 bass

Discussion in 'Setup & Repair [DB]' started by Benny McDowell, Feb 22, 2018.

  1. Benny McDowell

    Benny McDowell

    Feb 22, 2018
    Hello guys!
    I've seen this idea discussed on facebook for only just a second, and everybody was telling the guy how insane he was for having it. I am fully aware that this is not "recommended" and that a bridge is best with a foot over the bass bar.

    I'm curious? I've heard that a 4/4 bridge has a way of improving bass in the tone of an upright. Has anyone tried this or played the bass of another who was? I almost want to try it!
    I'm a bluegrasser playing on a (3/4) 1940 Kay M-1 that sounds as good as you'd ever want a bass to sound. I've got a set of 4/4 spirocores on it because I heard they also have a way of amplifying the instrument. I never really did a comparison, I just laced it up with 4/4's as soon as I bought it, it sure is loud though! It did however reduce the string tension.

    As a banjo player also, I have certain set up concepts drilled into my brain. Banjos have adjustable tailpieces that move up or down to change string tension, so I laced my bass backwards with the ball end of the string out front instead of behind the tailpiece to create more of an angle with the strings below the bridge to get my string tension back. It's not 100% but it's pretty darn close to my "traditional" tension.
    Banjo players are also picky about the thickness of their bridges, preferring thinner bridges because thicker has too much bass. Hhmmmmm

    Any and all input welcome, this is my first post here !
  2. Neil Pye

    Neil Pye

    Apr 13, 2016
    Horsham, UK
    Lacing the strings from below the tailpiece will make no difference to string angle and therefore tension. It's the geometry of the triangle formed by the nut, bridge and saddle that determines that. All of these things have been tried, and the "traditional" setup has become that because it works best. If the bass foot of the bridge is not over the bassbar, it will potentially cause major structural issues, and unbalance the sound of the instrument. I'm a great believer in not trying to re-invent the wheel. Look at your bass as an acoustic/mechanical system which has to sustain the tension of strings AND produce a balanced, even tone, and do it without falling to bits. Every component has a part to play, and hundreds of years of experience have gone into the way the whole thing works. I think overall you're better off doing the traditional thing
  3. Steven Ayres

    Steven Ayres Supporting Member

    Mar 11, 2007
    Northern Arizona
    I use wider bridges on my 5-strings, and on a Kay there's no difference in bass bar position between fours and fivers. The foot of the bridge has to be supported by the bass bar, that's not negotiable, but my wide bridges aren't so wide that they go off the bar. You can feel for the bass bar through the f-hole and tell whether you're really off the bar, I expect not. In any case a 4/4 bridge will have greater mass, but there's nothing else about it that's likely to effect the voice of the bass. A heavier 3/4 bridge will have the same effect without structural risk.

    I can confirm that threading the tailpiece backward will do nothing except screw up your afterlength and possibly add unwanted resonances. As Neil pointed out, it can have no effect on string tension or bridge break angle. The tailpiece will just move outward.

    For different string tension, we generally use different strings. Every type has a different feel on the instrument and offers subtle differences in harmonic response, tone and projection. I don't think you'll find many here who put 4/4 strings on a 3/4, because what matters is the quality of the string between the bridge and nut. At the same tuning the 4/4s will be less tense, sure, but there are 3/4 strings for that and you'll be less likely to break a string off at the peg.

    For myself I find lower-tension strings work better on my Kays. Less tension allows the sound table to vibrate more freely, which may be the "amplification" you're perceiving. Sound post adjustments can have a much bigger effect, however. I expect on most unserviced Kays the posts are too tight and too close to the bridge line.

    Just for the record (and speaking as a part-time banjo player too), a bass bridge is a far more complex acoustical machine than a banjo bridge.

    Finally, please take a look at this and consider registering your bass with Kaybass.com:
    Documenting Your Kay Bass
  4. BobKay

    BobKay Supporting Member

    Nov 5, 2012
    Estero, Florida; USA
    I owned a '51 M1B for 25 years. When I got it in 1990, it had a few "special" set up touches, based on some kitchen table bluegrass luthier's opinions. It sounded OK. Then, I had a new standard bridge cut, a new sound post, tailpiece and put on 3/4 length spiro mediums, and it sounded great, and much better than when I got it.

    And two years ago I discovered how much easier it is to play other basses with a more traditional neck profile, and sold the Kay. Haven't looked back. Low string height, great volume, better sound quality, and ease of playing. True, I sacrificed the Kay mojo, but I've owned three and the magic wore off long ago.

    There is certainly nothing wrong with trying out new methods and set-ups. I can't begin to understand why a 4/4 set of strings would amplify the instrument, but if you're happy then it really doesn't matter.
    eh_train likes this.
  5. Steven Ayres

    Steven Ayres Supporting Member

    Mar 11, 2007
    Northern Arizona
    Not meaning to derail the thread, but I have to point out that Kay necks vary by model due to varying fingerboard thickness. Maple fingerboards are quite thin, while walnut, ebony and rosewood fingerboards are all thicker to varying degrees. At Kaybass.com we've heard owner complaints about Kay necks being too thin and more traditional necks too thick. (Sellers frequently boast about the "thin, fast Kay neck.") Englehardt apparently made the decision at some point to cut its necks thinner than Kay and apply thicker fingerboards.
  6. GretschWretch

    GretschWretch Supporting Member

    Dec 27, 2013
    East Central Alabama
    This is the most liberating thing I've seen for those caught in the "vintage" snare regarding any instrument: the magic wore off long ago.
  7. BobKay

    BobKay Supporting Member

    Nov 5, 2012
    Estero, Florida; USA
    Steven - thanks for the additional information. I should have said: "...how much easier it is FOR ME to play..." I think one thing that changed for me is that I started playing a lot more than I had in the first 20 years I owned the bass. More practice, more gigs, more time on the neck, and thicker is easier for me. I thought seriously about handing it over to James Condino for a new neck, but went a different way. I also apologize for any derail of the thread.
  8. Harry Monkley

    Harry Monkley

    Jan 16, 2016
    If this is true, don't try fixing something that isn't broken - your body has limited mileage before it wears out, so having a bit less tension in the strings should in the long term extend your ability to enjoy playing the double bass, so smile and be joyous that you are not being crippled by tendonitis or carpal tunnel issues and get on with making music. It shouldn't take too long to adjust to the difference in string tension.
  9. Eric Hochberg

    Eric Hochberg

    Jul 7, 2004
    Actually, many on the forum and elsewhere use 4/4 strings on their 3/4 SL basses, spiros in particular. As you point out, they will have less tension than the same gauge 3/4 strings on the same bass. Some basses may respond better with less tension and less is easier on the hands. I don't think I ever used a set of 3/4 when I was playing Spiros the first half of my career.
  10. It could be that a thicker bridge (more weight) dampens higher frequencies, giving a darker/more bassy sound.
  11. Steven Ayres

    Steven Ayres Supporting Member

    Mar 11, 2007
    Northern Arizona
    I've found that heavier bridges tend to strengthen the fundamental on mine.
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