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Thread: Is the position of the braces on a mandolin important?

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    Default Is the position of the braces on a mandolin important?

    How does the position of the braces effect the sound and how do you know where and how to position them? I want to build my first A style mandolin but I dont understand the purpose of bracing. Can someone please explain it to me, thanks.

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    Fingertips of leather Bill McCall's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    Find a set of plans, oval or f hole, and follow them. There are many explanations of bracing or ‘tone bar’ specifications, some based on history, some on scientific understanding.
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    Registered User sunburst's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    Scientific studies of guitars and mandolins indicate that brace positioning is not important. Total mass and stiffness are the most important considerations regardless of how a top is braced.
    As for individual luthiers, I have no doubt that some can produce noticeably different sounds by using, say, "parallel tone bars" as opposed to an X-brace, but that cannot be considered a universal thing.
    Bottom line, we position them where we want to.

    As for the purpose of bracing, it gives the builder a convenient way to adjust stiffness vs mass and thus the frequencies of plate modes of motion. That might sound like a foreign language to a beginner, so the best thing to do starting out is: do what everybody else does. Standards of construction are there for a reason; they work. Just build a copy and move on from there in subsequent builds if you want to.

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    Default Re: Is the position of the braces on a mandolin important?

    Kudos to Sunburst! I have often wondered why I have been so slavish and diligent in removing wood from the top of an F or A to then add more mass back in to the top while installing braces. This will set off a deluge of folks who believe that the precise placement of braces is scientifically based.

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    Registered User sunburst's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    Quote Originally Posted by pelone View Post
    ...This will set off a deluge of folks who believe that the precise placement of braces is scientifically based.
    Probably not because there isn't really a whole lot of science out there pertaining to brace position, so it would be hard to site science supporting importance of brace placement to sound. The studies that I have read do not support importance of brace placement, and for what it's worth neither do anecdotes that are familiar to me.

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    Adrian Minarovic
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    Default Re: Is the position of the braces on a mandolin important?

    Just follow good traditional model like John said above.
    I just have a mandolin on bench made by reputable banjo builder and while the outside is very traditional with very nice work and good arches (I know he used my drawings as I sent them to him), he somehow decided to experiment inside and used odd bracing shape inside. The treble bar is much like guitar back brace - rounded top, flat along with scooped ends and the bass side bar resembles scalloped guitar braces. The sound is barely OK, plate thicknesses are reasonable (though could be hair thinner on the back) I believe if he used traditional slender Loar style tonebars the tone (and response) would be noticeably better...
    Adrian

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    Default Re: Is the position of the braces on a mandolin important?

    The OP questioned the purpose of braces. I'm not a luthier or an engineer but I believe the braces are there to disperse the downward stresses caused by the strings on the bridge. Much like like a roof truss or bridge beam functions. Otherwise the relatively thin top plate would fail. This may seem obvious to the knowledgeable luthiers here.
    As to placement I'll leave that to the experts and stand back and listen.
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    Registered User sunburst's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    Quote Originally Posted by Bob Gnann View Post
    ...I believe the braces are there to disperse the downward stresses caused by the strings on the bridge. Much like like a roof truss or bridge beam functions...
    Braces serve more than one function. Braces (or tone bars) do function as beams to distribute string/bridge load, but that is a static function. They also have dynamic function where they stiffen the top, sometimes selectively, and distribute mass so that the frequencies of plate modes can be adjusted by the luthier.

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    Default Re: Is the position of the braces on a mandolin important?

    Fully agreed John. The dynamic function will greatly effect the final acoustic results. And that's why we love having so many choices to sample.
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    Fingertips of leather Bill McCall's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    So, if braces act as beams, it seems they should run perpendicular to the grain of the top, and probably under the bridge, to provide additional top stiffness by shortening the length of the unsupported span. That would reinforce the arch and reduce sinkage, seen on older mandolins. It might allow some removal of mass from the top. Stiffening the top longitudinally would seem best done closer to the centerline, to prevent deformation along the long axis, tail block trying to rotate toward the bridge.

    I have no idea of the acoustic results of such bracing, nor the structural implications. But Gibson Oval models, both A and F had, I believe, a cross brace behind the sound hole, which would seem to me to function as a beam to prevent deformation around the sound hole. I have no idea of how other oval models are constructed.

    Complete speculation on my part, but it seems a question not unreasonable to ask. Btw, I haven’t searched old threads to see if this has been asked and answered.
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    Default Re: Is the position of the braces on a mandolin important?

    Like this? I made the transverse brace yesterday. Its not glued in yet. I felt like maybe this brace was necessary because I'm using sinker redwood, and I felt like I needed some extra support under the bridge. Comments?

    BTW - I'm working to scrape off the extraneous glue and gauze (and the scroll will be non-traditional).

    [IMG]Untitled by Gary Davis, on Flickr[/IMG]

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    Fingertips of leather Bill McCall's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    Yes. Could maybe make the long braces smaller, thinner not shorter.

    Edit: just noticed in the ‘recurve too thin’ thread has a comment about a European builder who uses cross bracing. Hmmm....
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    Registered User j. condino's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    This has been discussed endless times around here; the search button is your friend.

    I posted many times here and it has been well documented & demonstrated at many of the major luthier conferences: if you use my removable plate test rig, you can take your working mandolin top and try as many variations in the brace placement and thickness as you desire and can answer every one of these questions yourself instead of random internet speculation. It is well proven, well documented, and it works excellent.

    Here is a link to an old thread detailing a student experience using it:

    https://www.mandolincafe.com/forum/t...t=days+condino
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    Fingertips of leather Bill McCall's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    A search of ladder bracing on this site through Google doesn’t return much. The little bit it does return is about guitars and flat top mandolins.

    I get the value of the removable back jig and the bracing variations done by students, but didn’t see any discussion of ladder bracing in the link mentioned. A search of GAL abstracts doesn’t return anything on ‘ladder’.

    Interesting open area, apparently.
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    Registered User j. condino's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    Let's get the terminology straight. "Ladder bracing" is a common term in the guitar world to describe a series of braces perpendicular to the grain of the top woods that typically results in a sort of old timey, less defined voice and projection; often associated with lower priced instruments from the first half of the 20th century.

    I would not call the above image a ladder brace. It is a more traditional semi parallel set of tone bars combined with a single transverse brace as found on oval hole mandolins. There is no mention of any kind of ladder bracing in the above link because both of us already knew that it was not a voicing that we desire for a modern mandolin sound. I think the transverse brace is overkill and unnecessary in this application. If you want to stiffen the area under the bridge, do it from the outside of the instrument and use a solid bridge. That allows you to see how the increased stiffness works (as in John Reischman's change to his top sinkingF5), but you still have the ability to sand away at the bridge and open it up to allow a dipole action with the two sides of the top moving (slightly) more independently, rather than realizing it did not work so you need to remove the top. The area under the bridge is actually one of the most strong parts of the top because the bridge is supported by the two tonebars.

    When you make the choice to do something non traditional, nobody on the internet can give you exact advice as to what you mandolin will sound like to your ears. Different builder's all use different approaches. Some vary the species of wood, other the bracing position and size, others the arching, plate thickness, aperture position and size....and we all hear very differently. I can hear very subtle differences throughout the build of a mandolin. Others can duct tape a 5 lb cinder block to the top and not hear anything. Here we have a non traditional wood, a non traditional bracing pattern (combining two different application traditional styles does not = one singe tradition nor will any traditional voice correspond). I'll guarantee that you archings are different than those used by the other responders here, as well as your back species, arching, and dimensions, along with the rest of the instrument.

    The best way to answer these types of questions is to have a methodical approach that will allow you to make adjustments and tailor the sound - SOUND- not pretty pictures or fancy engineering graphs- the voice of the instrument- to your own ears and preferences. I've studied with and gone to some of the more advanced technical scientific gatherings of instrument builders anywhere in the country utilizing incredible scientific research labs but for me the desired end results are still the same. How does it sound? Does it have power & headroom? Will it knock over a guitar player with power, but can I still finesse fine tone out of it....et cetera. Musical qualities...

    We all want you to succeed. The best way to get close to a known voicing is to pick a known, well tested and proven design, then do your best to clone that. If not, build it with a methodical, adjustable approach.

    Simple version: If nothing else, cut the mass on those bars by about 1/3, drop the transverse brace, and go to the next step in your build, and keep us in as to how it goes....

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    Adrian Minarovic
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    Default Re: Is the position of the braces on a mandolin important?

    I was the one who suggested the additoinal brace in the other thread. But the situation was that he cut the area thinner and feared it would deform.
    For general build I would not use crossbrace under bridge.
    The maker I mentioned uses quite different approach on his current mandolins. He uses longer scale which puts bridge back a bit, he uses x-bracing and small additional bar angled like on flattop guitars. His archings of these is quite distinctive as well with kind of flat arch along the top (resembling violin arch). They sound nice and loud with big chop but "Loarish".
    Adrian

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    Registered User Tom Haywood's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    One of the main support aspects of brace placement is that the angle of the tone bars or X braces allows the bridge feet to be directly supported against the down force created by the strings. I believe gluing the braces at an angle across the grain of the top helps to maximize the strength of that support. I'm not so sure that additional support is necessary in the middle of an F hole instrument, either with additional bracing or a solid bridge, if the braces have enough mass. Whether the middle part of a too thin arched top would hold up against torque is a good question. I find it interesting that tone bar bracing traditionally is not inserted into the lining to add to the support. That is similar to cheaper construction in guitars, etc..

    I have no knowledge about GaryDavis' instrument, so I feel sure Adrian's advice is good. I have seen photos of "H" bracing that looks like this, though always on flat top, round or oval hole guitars or mandolin type instruments. From experience designing flat top instruments, I can tell you that adding braces sometimes results in surprisingly good sound and increased volume. The trick is to have enough mass but not too much. That is where voicing the braces comes into play. As James said, you are on your own with this one because it's not traditional, so let us know the end result.

    To the OP: Build your first mandolin according to a published plan. It takes several builds to get a basic understanding of the purpose of bracing, and, as you can see, opinions differ.
    Tom

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    Default Re: Is the position of the braces on a mandolin important?

    Mousing around on the net last week I found a pair of tourist-grade lutes or maybe ouds that were similar, but one had the top grain perpendicular to the long axis! Got me thinking about symmetry in wooden instruments, engineering design and other diversions. Is the idea overtly bad, or just unexplored?

  20. #19

    Default Re: Is the position of the braces on a mandolin important?

    Thanks all for your advice and experience. I'm not a musician so have no idea what sounds good or not. The mandolin is for my son who lives 500 miles away.

    This is my first mandolin and as a non-musician, I understand I should build closely to specs. I have done that as best I could. I left the redwood top a little thick. Cherry back is very close to plan specs.

    I will reduce the thickness of the tonebars and lose the transverse brace.

    Its hard to view this as a learning experience because I'll probably never build another mandolin. I'm also building a classical guitar so maybe something will transfer.

    Thanks again - Gary Davis

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    Fingertips of leather Bill McCall's Avatar
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    Default Re: Is the position of the braces on a mandolin important?

    The first guitar Arthur Overholzer built won an international competition. You can certainly bring a lot to your first instrument.
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    Default Re: Is the position of the braces on a mandolin important?

    My 2 cents on the subject after studying, experimenting, losing sleep over, etc.

    I agree it's about adding or controlling mass after carving the plate to target thickness. Their purpose is not structural, however the placement and shape do add beam strength even though not intentional.

    I like to think they function much the same way as the damping factor in a stereo speaker. Damping factor is the ability of the amplifier to control the movement of the speaker. More specifically, to be able to stop free vibration after the intended electrical signal has stopped. That translates into a tighter sounding bass. I've played a mandolin with overly thick braces, properly shaped, and without any at all. No bracing, the mandolin had no definition, bass was muddy, "floppy" you might say. I'll also claim that finish has the same effect, even a very thin layer. Play a mandolin in the white and then recently finished. I perceive more definition, tighter controlled low end with finish on. In fact, I don't really like the sound of a mandolin in the white. Something's missing.

    Feel free to shoot holes in my theory. I've found what works for me. I don't disagree with anyone's statements here. It's what I've observed. The longer I do this, I find you have to figure things out for yourself and stop spending so much time on the internet. James Condino's method of using a test jig body for each top has taught me more than I'll ever find on the internet.

  23. #22

    Default Re: Is the position of the braces on a mandolin important?

    Quote Originally Posted by j. condino View Post
    This has been discussed endless times around here; the search button is your friend.

    I posted many times here and it has been well documented & demonstrated at many of the major luthier conferences: if you use my removable plate test rig, you can take your working mandolin top and try as many variations in the brace placement and thickness as you desire and can answer every one of these questions yourself instead of random internet speculation. It is well proven, well documented, and it works excellent.

    Here is a link to an old thread detailing a student experience using it:

    https://www.mandolincafe.com/forum/t...t=days+condino
    I'm not sure what I was looking at on that link. Is that body and neck strictly for experimenting , is it just for testing the braces or are those exterior parts that the top and back get screwed to removable? This is definitely something I will want to play with. Thanks
    Richard Hutchings

  24. #23

    Default Re: Is the position of the braces on a mandolin important?

    Never mind, I went to the other link and all my questions were answered. Can't wait to build another mandolin.
    Richard Hutchings

  25. #24

    Default Re: Is the position of the braces on a mandolin important?

    I strongly believe they should be attached to the top of the mandolin.

  26. #25

    Default Re: Is the position of the braces on a mandolin important?

    What a cod
    Richard Hutchings

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