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Changing bridge adjuster formats

Discussion in 'Setup & Repair [DB]' started by Thumpie, Nov 27, 2012.

  1. Which format is larger, the 6x1mm or 1/4-20?

    If you started with the smaller, would you be able to drill a new hole and step up to the other type?

    One of my basses has 1/4-20, and I was wondering if I could retrofit the Yamahiko pickup (which is 6x1mm) on this bridge...
  2. keiranohara

    keiranohara Commercial User

    Nov 7, 2007
    Ossining, NY
    Luthier at AES Fine Instruments
    1/4"-20 expressed in metric would be 6.35x1.27mm
  3. robobass


    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    No, you can't simply re-tap. The 1/4-20 is slightly larger. You could get metal inserts though, which I recommend anyway for 6x1mm, as that thread is really a bit too fine for maple. I don't know where to source the inserts, but I think they are not hard to find.
  4. Cody Sisk

    Cody Sisk

    Jan 26, 2009
    Lilburn, GA
    Ronald Sachs Violins
    Since I thread the feet of the bridge, I've had success in the past installing a boxwood peg bushing and redrilling/tapping the hole. This is kinda tricky to get lined up right though..
  5. robobass


    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    True. You could fill all the holes and re-drill, in fact, but it seems like installing inserts would be less trouble.
  6. james condino

    james condino Spruce dork Supporting Member

    Sep 30, 2007
    asheville, nc
    Any good auto parts store will sell you a helicoil for about $1 that will let you change thread sizes; they work like a thread within a thread. It may not be a perfect final setup, but they go in with minimal effort and you'll be able to try out the new system within 15 minutes.

  7. misterbadger

    misterbadger Supporting Member

    Sep 13, 2012
    Northern California
    Helicoil's not the best idea in wood. Threaded inserts (Murakoshi is a well-known brand but others are available) with the desired tapping can be easily sourced on the internets.
  8. iiipopes


    May 4, 2009
    Why bother? You already have one of the larger adjusters. Now, for example, if you want to change the tone of a Full Circle by inverting its mounting, that is an actual reason. But simply to change for the sake of change is a waste of time and money. The 1/4 inch bolt is already one of the larger bolts used for adjusters, it is well tested and proven as sturdy enough for double bass use, and anything smaller would simply be a regression to instability.

    As far as the pickup, it is functionally the same as a Full Circle with one drawback: with two elements, you will get phasing issues. I don't recommend it. I believe it is overpriced and overhyped when a Full Circle will do the job better, with no modifications to the bass, and at less expense.

    My advise: spend your money on a Full Circle and an fdeck and be done with it.
  9. A one-element version is available. And it offers the advantage of being able to remove the cables when not needed.

    Why do you believe the Full Circle is better? Have you tried the Yamahiko?

    I doubt I'll get one since the modification would be a pain, but, otherwise, I'd be open to experimenting with it.
  10. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    I agree with this viewpoint, in general. As for "phasing issues," I posted a calculation a while back showing that, considering the velocity of vibration through wood and the relevant frequencies, the small separation between pickup elements as would be the case for the Yamahiko, would not be expected to produce destructive interference of any practical consequence. That aside, I think "if it ain't broke, don't fix it" applies. Even if Thumpie perceives there to be drawbacks to the FC, then it's not clear that the Yamahiko will provide a substantial improvement. In order to find out seems to require substantial expense and modification.

    One drawback of the FC and the Yamahiko that I see is shared by many other pickup systems. That is the inflexibility in terms of positioning. While many might perceive the "uncertainty" of the Ehrlund's response in terms of where it is located as a drawback, I see it as a benefit. The enormous flexibility it offers in terms of positioning and the character of its response on specific basses makes it all the more likely that one can achieve a satisfactory (and, in my case, wonderful) result. One just has to be willing to put in the time.

    As always, it's for Thumpie and any other player to decide. All we can do is give our opinions from the peanut gallery. :)
  11. It is seems to make sense that phasing wouldn't be a problem--why would they be designed with 2 if this was the case?

    To be clear here, I'm not replacing the Fishman I own. I have a 2nd bass that doesn't have a pick-up and was considering loading it with a Yamahiko as an experiment. This is mostly terra incognita for us western bassists, so I was considering doing a little exploring. But I don't really want to get a new bridge, and the options to modify seem unsatisfactory. If I ever get adjusters installed on a bass, I'll request the metric format with the Yamahiko in mind.

    The Ehrlund is seeming more likely like something I'll pursue--anybody know the best (cheapest) place to order one? Maybe I can find one used...
  12. robobass


    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    I wouldn't do it. As I said, the 6x1mm thread is slightly smaller and about 25% finer than 1/4-20. This makes it less than ideal for maple, so most German luthiers use inserts when installing metric adjusters. 1/4-20 works really well directly in wood, by comparison, so whenever I bring a bag of them over from the States my luthier buddies snatch them up like hotcakes!