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Thread: What are these bridges called?

  1. #1

    Default What are these bridges called?

    Hey folks:

    I have encountered a couple of bridges in the wild that I am fascinated by, and have no names for. The first is the bridge on the cover of Hal Leonard's Irish Bouzouki Method (maker's name seems to be something with "Taylor," and the whole thing is a bit of a trip), and the second is this APC bouzouki found on Reverb here.

    All the search terms that come to mind for this are too general: "over-under" and "string-through" are particularly unhelpful. I am content to satisfy my curiosity with the names, but if you happen to know why they're so rare, that'd be even more awesome. =)

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  2. #2
    Moderator MikeEdgerton's Avatar
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    Default Re: What are these bridges called?

    The second one is an interesting solution to a six-string conversion. I have no idea what to call either of them.
    "Bargain instruments are no bargains if you can't play them". These are the words of J. Garber.

  3. #3
    Registered User Martin Jonas's Avatar
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    Default Re: What are these bridges called?

    That's a strange hybrid between a floating bridge and a fixed pin bridge: it needs the tailpiece from floating bridge but needs to be fixed to the top in order to prevent the torque generated by the string angle changes flipping the bridge. If you need to increase string break angle, a neater way may be to use a separate string downholder like the old De Meglio or Ceccherini bowlbacks: that way the bridge remains floating and only the downholder is screwed into the top.

    The only mandolins I know of where similar hybrid bridges are part of the inherent design are the Gelas style -- these need a fixed bridge with multiple changes of string angle in order to generate any downwards pressure on the saddle.

    As far as the two examples you have posted, the first looks retrofitted and rather crudely screwed into the soundboard. The APC bouzouki reminds me of the Ovation bridge, which takes ball-end strings but doesn't use pins. In principle you could fit a tailpiece to an Ovation and have the strings terminate there rather than at the end of the bridge. That would look similar as on the APC.

    Martin

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    Registered User Buck's Avatar
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    Default Re: What are these bridges called?

    Quote Originally Posted by fuz View Post
    ....but if you happen to know why they're so rare, that'd be even more awesome...
    Sometimes a thing is rare because it's difficult to execute. Other times it's rare because it's a bad design and no one wants it. I think these are examples of door number 2. As noted above, the strings must be anchored at the tail, but the bridge must be anchored too. So, you have a bridge that wants to come off, but the torque is not fully loading the top. I see no up side to this design.
    Todd Yates

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  7. #5

    Default Re: What are these bridges called?

    Bridge (2) is interesting. Depending on the exact geometry it could have an overturning torque, that is, pressure up at the back and a similar, but not equal downforce at the front. No need to bolt it in, but the advantage remains mysterious, as the total net downforce is the same as a usual bridge.
    Bridge (1) is unclear. Maybe it’s adjustable with those two (pin/screw?) locations. Maybe there’s some concept related to where vibration is transmitted to the top structure. Or maybe just a random idea.
    I know that shaping the foot of a bridge to closely fit the contour of any string instrument top is standard practice, although, for mandolins in particular, transmission from the strings to the (separate) lower bridge can be ok with just two little screws that don’t seem to be part of an acoustic design, as it definitely is in something llke a violin bridge. Another mystery.

  8. #6
    Confused... or?
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    Default Re: What are these bridges called?

    Quote Originally Posted by Martin Jonas View Post
    ... strange hybrid between a floating bridge and a fixed pin bridge ... reminds me of the Ovation bridge, which takes ball-end strings but doesn't use pins.
    It's interesting that floating bridges (w/ tailpiece), common on archtop instruments, are generally assumed to impart an up & down motion to the soundboard, while fixed pin bridges, as per flatops, are assumed to impart a rocking motion (as the string pulls on and releases tension from the bridge, without an opposing pull from a tailpiece). The hybrid shown here would seem to, uhmm, ATTEMPT both motions at once, but more likely cancels out a portion both motions. Just one amateur observation.
    - Ed

    "What our group lacks in musicianship is offset by our willingness to humiliate ourselves." - David Hochman

  9. #7

    Default Re: What are these bridges called?

    Thanks for posting pictures of these curious bridges. I think the concept might enable some sort of design feature where break angle becomes a problem. Something similar is employed as a modification on a few electric guitars that border on a design flaw due to a very shallow break angle such as the Jazzmaster and the Jaguar. The aftermarket device I've seen is called a Buzzstop. If you were to build a basic solid body with no neck angle, something like this might be appropriate. There might be a way to take advantage of the torsion action to promote the use of a piezo element and maybe worth some experimentation. Im seriously not an engineer but along the length of the torsion leverage the force of downward string vibration would change -- I know I'm not saying this right but somebody might see an advantage.

  10. #8

    Default Re: What are these bridges called?

    I call them (at least the top one) "zero downforce bridges". I think I got that from a GAL publication, not sure who coined it. Of course the downforce is not exactly zero, but probably a pound or so instead of dozens of pounds. The idea is that you can make the top lighter since it doesn't have to deal with the downforce of the string tension.

    Now that I think about it, it might be "zero break angle" bridge. Anyway, it's a significant departure from traditional soundboard design- it's not about the bridge, but about a soundboard that only has to deal with producing sound and a bit of compression from the tailblock, and the bridge doesn't just plug in to an existing instrument.

    If you want to see something really crazy, look at Nigel Forster's archtop guitars.
    https://www.nkforsterguitars.com/ins...chtop-guitars/

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  12. #9
    Registered User Tavy's Avatar
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    Default Re: What are these bridges called?

    The closest historical comparison to both of these are the DeMeglio style bridges:

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    In all 3 designs the "bit behind the bridge saddle" compensates for a lack of downforce on the bridge saddle. In all 3 cases the "bit behind the bridge saddle" is pulling up on the soundboard and so has to be firmly attached to it. The net effect is to push the top area of the soundboard down, and pull the bottom area up, so the bracing had better be able to cope with that. The forces are similar to those imparted by a regular guitar pin bridge when you think on it.

    The Gelas design is somewhat different, in that the strings contact the bridge assembly at 3 points rather than 2, so now the net effect is no downforce on the top, and no twisting motion either:

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    Actually the geometry of the Gelas instruments is such that the bridge actually pulls up on the soundboard!

    American Luthier Rick Toon has patented a system remarkably close to the Gelas one that he calls a "Neutral Tension Bridge":

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    I remember hearing a sound clip of one and thinking it sounded more like a bouzouki than a guitar (crazy long sustain) which rightly or wrongly I attributed to the bridge design.

    None of which tells you what you're examples are called

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  14. #10

    Default Re: What are these bridges called?

    I've never seen anything like this! Very beautiful, and look so rare) I want one, please :D

  15. #11

    Default Re: What are these bridges called?

    Quote Originally Posted by Tavy View Post
    American Luthier Rick Toon has patented a system remarkably close to the Gelas one that he calls a "Neutral Tension Bridge":

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    I remember hearing a sound clip of one and thinking it sounded more like a bouzouki than a guitar (crazy long sustain) which rightly or wrongly I attributed to the bridge design.
    Anytime you eliminate a need for a portion of the top to resist constant mechanical forces to just stay intact, you can instead just let the soundboard concentrate on being stiff and lightweight in the center, and extremely flexible around that stiff plane. You also eliminate loss of string vibration to that previously required overbuilding, giving you more volume and sustain.

    I've now been lucky enough to play a few instruments which eliminated some of those forces.

    My various carbon fiber guitars over the years feature a soundboard which is lighter and stronger than a wood soundboard, thus having more volume on tap, as well as not damping the upper frequencies of the strings. Some people find the accurate reproduction of the strings' full ranges to be irritating. I find it to be pure and crystalline, like a wire-strung harp.

    I have never own an early Ovation Adamas guitar, but the soundboard was made of a sandwich of carbon, then balsa wood, then carbon again. This was much thinner, stronger, and stiffer than a wood soundboard. Rather than requiring the soundboard to flex around the edges, Ovation also put the soundboard on a suspended ring on those edges. The suspension acted like the foam surround on a stiff speaker cone, only serving to seal the edge against sound leak while letting the whole surface vibrate. The stiffness of the soundboard, coupled with the elimination of energy loss at the edges, led to volume and sustain for what felt like days. Maybe someday I'll find the early Adamas 12-string of my dreams for the right price.

    The other instrument I got to play was a guitar by Dixie Mitchell, which eliminates string pull on the body by instead relying on a metal rod from headstock to tailpiece. By eliminating vibration loss through body flex, and allowing the soundboard to just be a soundboard and not a required reinforcement against tension, she was able to build pretty loud, sustaining instruments. She sold instruments through Gruhn and I never got to try/buy one of her mandos before she passed away.

    ----

    Just to also comment on normal guitar and mandolin construction, I worked music retail for many years in a specialty acoustic shop, featuring guitars, bowed and mando instruments, as well as instruments for many musical traditions. We noticed some things in comparing various pairs of either guitars or mandos which varied in just one detail.

    Just regarding the specific differences between f-holes and oval holes, f-holes dampen upper harmonics *and* sustain. The two cuts into the sides of the opposite sides of the vibrating plane of the soundboard mean the soundboard either needs more strength at the top and bottom to conpensate, making it thicker and more sluggish/less springy, or instead to have less strength and thus to dampen more of the vibrations.

    Tops with an arch tend to have more immediacy, but more dampening, both of upper harmonics and over time. Flat tops had more upper harmonics and richness, and more sustain.

    And, of course, if an instrument was really overbraced or overfinished, that would kill off sound too.

    ----

    I've considered either getting a Toon mando instrument (mandola or cittern) with a few of his build ideas, including the aforementioned bridge, or of just going for a custom carbon fiber cittern from Emerald Guitars. I've greatly admired my various CF guitars, both their sound and their durability and imperviousness to environment, so that might drive my decision....

  16. #12
    Registered User Martin Jonas's Avatar
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    Default Re: What are these bridges called?

    Quote Originally Posted by Tavy View Post
    The closest historical comparison to both of these are the DeMeglio style bridges:

    In all 3 designs the "bit behind the bridge saddle" compensates for a lack of downforce on the bridge saddle. In all 3 cases the "bit behind the bridge saddle" is pulling up on the soundboard and so has to be firmly attached to it. The net effect is to push the top area of the soundboard down, and pull the bottom area up, so the bracing had better be able to cope with that. The forces are similar to those imparted by a regular guitar pin bridge when you think on it.

    The Gelas design is somewhat different, in that the strings contact the bridge assembly at 3 points rather than 2, so now the net effect is no downforce on the top, and no twisting motion either:

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    Actually the geometry of the Gelas instruments is such that the bridge actually pulls up on the soundboard!
    Thanks, John.

    I agree it's functionally similar to the De Meglio system, except that De Meglio still allows the bridge to be moved (within limits) for intonation purposes by fixing only one of the break angle points to the soundboard rather than both.

    You're right in saying that the patented Gelas system has three break angles so as to cancel out the torque. However, some later Gelas-type instruments (including my own Rene Gerome) dispense with the additional saddle at the tail end of the bridge and instead go for more substantial anchoring to allow the soundboard to withstand the torque. That leaves only two points, much like in the photos from the OP, except that with Gelas the overall force on the soundboard is upwards, not down.

    Martin

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    Phil Goodson Philphool's Avatar
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    Default Re: What are these bridges called?

    So what do these bridges say about all of our discussions about downforces on the bridge and how it relates to volume, tone, etc?
    Phil

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  19. #14

    Default Re: What are these bridges called?

    Quote Originally Posted by Philphool View Post
    So what do these bridges say about all of our discussions about downforces on the bridge and how it relates to volume, tone, etc?
    Nothing, really. It's a completely different structural concept. Both can work, but it's a little like comparing a tractor to a Ferrari. Both are powerful, but different approaches.

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    Registered User Charles E.'s Avatar
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    Default Re: What are these bridges called?

    I can not find a whole image of the "guitar" that the Rick Toone bridge is on but that looks like a very ineffective bridge placement to me. Almost zither like.
    Charley

    A bunch of stuff with four strings

  22. #16

    Default Re: What are these bridges called?

    Quote Originally Posted by Charles E. View Post
    I can not find a whole image of the "guitar" that the Rick Toone bridge is on but that looks like a very ineffective bridge placement to me. Almost zither like.
    I'm pretty sure it's not intended as solely acoustic. All his other instruments are (amazing) deconstructed to a pretty significant degree, so I think this is his deconstructed acoustic.

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    Registered User Lou Scuderi's Avatar
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    Default Re: What are these bridges called?

    I don't know anything about the second, but the first looks something like Herb Taylor's experimental low-tension bridge. He's put together a few of those instruments-at least three to my knowledge, one owned by Ken Gilman and one (the first one) owned by Roger Landes. Not sure who has the other (or if there are more out there). They have very thin tops and this low tension bridge helps to make sure they don't explode. Because of that, they're fairly loud.

    Looking more closely at the picture, though, I'm kind of doubting whether that really is one of Herb's. The bridge design certainly looks like his, but I don't recognize the instrument.
    My Instruments:
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