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Originally Posted by mc1
i take it you are bothered by the use of the word "parabolic"?
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That is one issue, yes. There is nothing "parabolic" about the longitudinal shape or the cross-sectional profile.
The comments adjoining the video, made by the author, state a bunch of things that can only be described as "mis-informed".
I guess I'm late to the "parabolic bracing" picnic, so to speak. Here is what Scott van Linge has to say on the subject,
http://www.harmonycentral.com/forum/...1350923-/page2 (note that the websites listed below no longer work.)
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I may be partly responsible for introducing ''parabolic'' to the consciousness of the guitar world when I founded Parabolic Brace Works in 1996, a business in which I reshape existing braces to maximize a guitar's potential. I shape braces in length and cross section in approximately parabolic curves, although I do not follow a strict formula. This allows the energy from the strings to flow through the braces to the soundboard in a streamlined manner, while reducing unnecessary mass (i.e., not needed to balance string tension). Corners, ridges, peaks (as left by scalloped bracing) all absorb energy before it can make sound. Scalloped braces are not parabolic, and I feel are a cheap fix to loosen up the top, which can cause failure, although they do allow for better sound than even-height braces used by Martin in the 50's-70's. Larrivee shapes their top braces parabolically lengthwise, but leaves them square cut in cross section, which leaves corners the entire length.
If you ever get a chance to look into a vintage Martin, you will see parabolically shaped back braces, both lengthwise and in cross section. I have seen variations on top braces that were not completely scalloped, and the short side braces were parabolic back then. Another term used for lengthwise shaping is ''tapered'', which also describes a gradual lowering in height as the brace ends. This allows the strength and mass to be reduced as the braces move away from the string tension area under the bridge, much as it takes less force to balance a teetertotter further out from the fulcrum. I have gone into detailed discussion and posted pictures on my web site, vanlingeguitars.com. parabolicbraceworks.com will get you there, too.
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