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Old 09-28-2021, 04:12 AM
RJVB RJVB is offline
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Default Solid v. "lacey" bridges?

Hi,

I've been wondering about the bridges (saddles?) used on archtops. They look HEAVY, either because of the use of metal hardware or else because they're tall and wide chunks of dense wood that typically seem to lack "feet".

Coming from the violin that never ceases to surprise me; in that universe bridges can be impressive too but they're always carved out in such a way that they retain sufficient structural strength but lose a lot of "dead" weight. In addition, the contact points with the top are kept small - despite string tensions that AFAIK can far exceed the tension guitar tops are subjected to. They're also made of a light wood, maple - and not the densest kind either (my violin originally had a flame-maple bridge which made it sound shrill).

The latter is undoubtedly possible only because of the presence of a bass bar on one side and a soundpost on the other. I know the latter can't be used in a plucked instrument but the bass bar is basically just a brace - and my own old German archtop has its single brace sitting right under the bridge (which incidentally has two rather heavy feet, and appears to be maple).
NB: I have no idea if the design of the carving has a lot of importance.

So why are archtop bridges not carved out to make them lighter, and why do they contact the top over their entire width? I could imagine that this might affect the frequency response, but that would also apply to adjustable-height bridges where all those frequencies have to pass through the two bolts of the adjustment mechanism.

As related elsewhere, I'm toying with nylon strings on that old German archtop because it's in bad shape (a heritage that only has some sentimental value but sounds kind of cute). I could of course just experiment with drilling some holes through it (no need for fancy carving) - would I go for fewer, larger holes or rather a larger number of smaller holes?

PS: I suppose acoustic archtops can be muted with the same kind of mute used on bowed instruments, for late night or hotel room practice?
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Old 09-28-2021, 04:39 AM
dkstott dkstott is offline
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This website told me everything I wanted to know about archtop bridges

http://koentoppguitars.com/blog/the-...et-or-no-feet/
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Old 09-28-2021, 05:08 AM
RJVB RJVB is offline
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Thanks. It does confirm what I thought but it's also a bit "everything is possible, just leave it to an expert"
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Old 09-28-2021, 05:55 AM
Mandobart Mandobart is offline
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Orchestral stringed instruments are bowed most all the time, not plucked. The sustain when plucked (pizzicato) is minimal. Their bridges are optimized for sonic transfer and response when bowed. The cutouts in their bridges aren't to save weight, they influence how the vibrations reach the soundboard.

Plectrum or fingerstyle played arch top or floating bridge instruments (mandolin, mandola, octave mandolin, mandocello, banjo, guitar, etc.) bridges are optimized for sonic transfer and response when being picked or strummed. Also, the height of the bridge above the soundboard on one of these instruments is way less than on a violin, viola, cello, etc. Similar action on an archtop guitar from a bridge like that would make it unplayable.

That said there are bridge makers (Red Henry for one) that make one-piece bridges for mandolin with cutouts similar to a violin. I've stumbled across similar concepts for archtop guitar. I have never tried one myself. On most gypsy jazz guitars the floating ebony bridge is a one-piece design with the saddle portion partly hollowed out. These guitars are quite loud and not typically known for sustain.
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Old 09-28-2021, 06:20 AM
RJVB RJVB is offline
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Quote:
Originally Posted by Mandobart View Post
Orchestral stringed instruments are bowed most all the time, not plucked. The sustain when plucked (pizzicato) is minimal. Their bridges are optimized for sonic transfer and response when bowed. The cutouts in their bridges aren't to save weight, they influence how the vibrations reach the soundboard.
After reading the article linked in the previous reply I'm fairly confident that the cutouts influence the way vibrations reach the top by reducing (and how they reduce) mass (i.e, weight ). Mass that isn't there can't absorb vibration energy.

It is my understanding that sustain is largely a function of what happens inside the resonance chambre although evidently it also has to do with how well string vibration energy is transmitted. A bridge is essentially a measurement too, right? It should transmit an accurate reading of the string vibration to the top, without altering that observable (= without dampening the string).

FWIW, violins have very little sustain indeed when played pizzicato (esp on the higher strings), violas a bit more already, and cellos and double basses have a very decent sustain. Esp. those in period set-up. Idem for viols; on his recording of Bach's cello solo suites, Paolo Pandolfo plays one entirely in pizzicato (probably on a regular bass gamba, i.e. not an archback Tielke model). I'd be very happy with a guitar sounding that good!
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Old 09-28-2021, 11:10 AM
RLetson RLetson is offline
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The thing about tailpieces and bridges--or saddles or nuts or soundholes or bracing--is that any single element of a guitar is just that: one element in a system in which all the elements interact to some degree. The conventional archtop bridge/saddle is a composite of materials (wood plus height-adjustment thumbscrews) and design, and some modern designs sacrifice easy height adjustment by doing away with the metal bits. Just as some builders follow Benedetto's decision to replace the metal tailpiece attachment with a cello ligature.

The bridges of Selmer-style guitars are often made lighter by hollowing out their undersides, following the less-mass-is-better assumption, but the tailpieces are invariably metal, usually stamped and relatively light. (A common cutomization is a different, usually lighter, bridge.) But Michael Dunn's bridges are solid with larger feet and his tailpieces are generally made from heavier flat stock and have heavy hexagonal string anchors. I'm not sure what role those elements contribute to the characteristic Dunn voice, but I suspect that other construction elements matter more.

I'm not sure what the outcome of a project that marries nylon strings--even the Savarez 520P set with the wound G and B--to an existing archtop would be, but I would be braced for disappointment. Building an archtop with nylon strings as the central part of the design would be something else altogether, though.
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Old 09-28-2021, 02:09 PM
RJVB RJVB is offline
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Tail pieces typically don't rest on the top, do they? I wouldn't be surprised if with a floating bridge, the tailpiece either has to be fixed in a very stiff way to the tailblock, or have sufficient mass to resist being driven by residual string energy.

Quote:
Originally Posted by RLetson View Post
I'm not sure what the outcome of a project that marries nylon strings--even the Savarez 520P set with the wound G and B--to an existing archtop would be, but I would be braced for disappointment. Building an archtop with nylon strings as the central part of the design would be something else altogether, though.
Aquila make strings that have a higher tension and probably better sound than those Savarez and if more clarity is required there are the steel string sets for classical made by Thomastik. Anyway, the guitar is itself braced for, well, not sure what (single brace that's come loose over about 1/3 of its length in total). The neck is warped due to having been stored under tension in bad conditions, so the action is about right for nylon strings (and I get a reasonable range up the fretboard before the warp effects kick in). Bringing the action back down to playable with steel strings of appropriate tension (for me) would require a neck reset. In short, it's probably either making the best with high tension classical strings, or spend way more money than the instrument is worth (even in terms of sentimental value). This question was not just about this instrument though.


As to dedicated designs: Slaman's The Dome is something else indeed. IIRC it exists with a floating bridge but also with a fixed pin bridge which presumable drives the top in a very different fashion.
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Old 10-06-2021, 12:56 PM
MC5C MC5C is offline
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My experiments with archtop bridges, of which I've made a bunch, are that surface area of the "feet" has a dampening effect on vibration transfer but a beneficial effect on top wear, that lighter is always better than heavier, that stiffness is beneficial, and that sometimes practicality over-rides minute sonic advantages. Ken Parker has made bridges of hollowed out spruce with a bone saddle - in my world that is pretty **** good, it has a small footprint on the top (the perimeter of the hollowed out base, it's very light, it's very stiff, and he has an adjustable neck so he doesn't need an adjustable bridge.

As far as surface area of the feet to transfer vibration to the top, imagine a really simply experiment. Tap an old time tuning fork and touch the ball to the top of the guitar. Instantly a loud, clear tone emerges. The surface area of the interface between a sphere (the ball of the tuning fork handle) and a plane (the top, or the edge of the bridge foot) is theoretically zero - where they touch defines a point, of zero dimension. If that point transfers energy so well, why does a big, flattish, massy bridge foot, one or two of them, improve on that? Answer - it doesn't, it dampens the energy of the transfer.

After making all the bridges, and testing all the ideas, I went back to using a typical bridge with two threaded rods and and spinny adjusters, so I could focus on playing and not on what humidity changes were doing to the set up of my guitars. Practicality trumped fleeting perfection. On my guitars, to get them to play the way I need them to, I adjust both bridges and truss rods monthly, if not weekly. I play with very low action because of nerve damage in my left hand.
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Old 10-06-2021, 04:07 PM
RJVB RJVB is offline
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It just occurs to me that you could maybe combine the putting the bridge on a diet by drilling holes in it with a cleverly designed bone saddle insert that uses the holes and 2 pins to provide a form of height adjustment?
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Old 10-11-2021, 09:55 AM
MC5C MC5C is offline
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Yes, and several have made exactly such a bridge. But you do quickly get to a point of diminishing returns. After spending a day or two making and fitting such a bridge it surely MUST sound better, after all the effort, and so it does... After two or three days you can't remember what the guitar used to sound like, so the way it sounds now (maybe with new strings) just has to be better...
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Old 10-11-2021, 11:41 AM
RJVB RJVB is offline
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Quote:
Originally Posted by MC5C View Post
After two or three days you can't remember what the guitar used to sound like, so the way it sounds now (maybe with new strings) just has to be better...
That's why you made recordings, right?

BTW: "German Vintage Guitars" very briefly had a Roger Junior CA from the 60s for sale, I noticed that its bride had a series of holes. It's gone from their website but you can kind of see them here:
https://www.facebook.com/germanvinta...20756224777769
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Old 10-17-2021, 01:11 PM
RJVB RJVB is offline
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I've been trying to address the buzzing caused by the loose brace by pouring some white woodglue via a small hose (a part of one of the lines in a maple tapping kit). It struck me that the brace would probably move back towards the top if I took the tension off the instrument, mimicking the action of the clamp I couldn't install. I decided to use the occasion to take the bridge off, clean it up a bit, file down the "belly" (that may or may not have touchd the top) and drill a series of holes in it.

Evidently me being my distracted self, somewhat rusty in my empirical approaches and having only just finished my morning coffee I forgot to weigh the bridge before drilling it.

Before:



After drilling, tapping, polishing and treating with lemon oil:



I'll have learned for a next time to start with a thinner drill bit, and work from both sides to avoid having to polish away the splintering I got now. Overall I'm not discontent with the result. The guitar may even sound a bit more open, resonate more (with the same caveat emptor that MC5C noted ).



I'll give her a few days to settle (the new brass strings idem) and will then decide what to do with her, not really intent on keep her ATM.
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Last edited by RJVB; 10-17-2021 at 01:16 PM.
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Old 01-08-2022, 04:41 PM
Sage Runner Sage Runner is offline
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Default Solid arch top Bridge

I meticulously carved super light Brazillian’ R/W Bridges for my 2 vintage Epiphone’s. My 42’ Ritz sports a Bridge designed Two feet— and also made a Brazilian String/Tailpiece cross Bar. My 53’ Zenith sports a Solid base Bridge with Three hole/cut outs. Both sound great. Can’t seem to be able up-load pics
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Old 01-24-2022, 03:28 PM
Sage Runner Sage Runner is offline
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Here’s a Brazilian RW Bridge I carved for my 1942’ Epiphone Ritz’. I also carved out a Brazilian Tailpiece cross-bar. Gave the old 15” Ritz a little Warmer sustain. 215F9437-DBE4-45CB-A583-C3AB20F991B4.jpeg
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Old 01-24-2022, 04:11 PM
RJVB RJVB is offline
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Does the cross-bar have any effect on sound? I'd expect a heavier tailpiece to give a brighter sound because it should vibrate less.
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