Official Luthiers Forum!

[QUOTE=Don Williams] There seems to be a misnomer about what parabolic bracing is. Some folks errantly (IMO) think it has to do with the shape of the brace end to end in profile, but that is incorrect. It has to do with the cross-section of the brace.
Scalloping is merely removing an arched notch(es) out of the profile.
[/QUOTE]
That was sort of the point of my post. What were people talking about when they said parabolic bracing? Some talked about the cross section while others talked about gentle curves along the length of the brace.

Some startling claims have been made where guys take existing instruments and reshape the braces to be "parabolic" and then get marked sound improvements. Some of these instruments aren't scalloped to begin with.

Don, the guy who coined and promoted the term (Scott van Linge) pretty
clearly uses it in the way you say is incorrect.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

[QUOTE=Howard Klepper] Language both evolves and devolves. When a term with precise
meaning is rendered less meaningful by its use in place of a term with
less precise meaning, we have devolution.

Using "parabolic" in place of "convex" or "arched" is a case of devolution.
[/QUOTE]

devolution

noun {U}

the moving of power or responsibility from a main organization to a lower level, or from a central government to a regional government


Howard - "Bracing for the people". I just love it

Seriously though I can never really understand why the term "parabolic" generates such strong and somewhat "hostile" positions. I use this shape of bracing for many of the reasons Alan states above: -

"The sustain and treble tend to be greater, and there's a tendancy to 'clarity'."

I use other parts of my design to give balance across the strings. Bass thump I am not after at all. I have never advocated "tapered" over "scalloped" as if one was superior or inferior.

Confused builders can always enquire and dig further, experiment (which is what I did) - or not. The whole guitar making language is littered with terms that can confuse and are less than crystal clear but that is all part of the fun of learning.

Dave White38730.6887152778

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Dave, I don't see Howard's response to arched bracing as negative or even hostile, but he's got a point when he says we should call things what they are, if at all possible.

I don't care how many people say they use 'kerfing', I'm still calling 'em kerfed linings. And I'm fine with saying you use vaguely 'parabolic' bracing, but leave the quotes in there, to make sure it's clear it ain't *actually* parabolic by any mathematical standard.

Language is fun, but it's more fun when used properly, accurately, concisely than it is when bandied about willy nilly.

...ok, maybe it's funnier if you bandy it about like certain high-placed politicians do, but it doesn't make it more useful

[QUOTE=Howard Klepper] Don, the guy who coined and promoted the term (Scott van Linge) pretty
clearly uses it in the way you say is incorrect.[/QUOTE]


Howard, That doesn't make him right...nor the originator of the term. I would argue the point that he coined the phrase. What proof is there, other than in his own use of the term for what he does? How do we know someone else way back in the early Martin days didn't use it? Cumpiano and others have been talking about barabolic bracing in the manner I said for years. Just because Scott van Linge uses it the other way doesn't mean that's what everyone else in the industry means by it, nor does it mean the term is applied correctly.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Mattia,

Point taken. Maybe we should set up a "Luthier's Grammatically Correct Phrasebook" on another thread. For example what on earth does a "compound radius fingerboard" mean? Shouldn't it be "compound radii" or even "multiple radii"?? Your's confused of Hughenden Valley

Thanks Don, from now one I'm going to refer to my bracing as "barabolic"

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Howard, That was great! I found myself belly-laughing at your descriptions, and nodding my head in agreement with the crucifixion of the English language!

ROTFLMAO

[QUOTE=Dave White] Mattia,

Point taken. Maybe we should set up a "Luthier's Grammatically Correct Phrasebook" on another thread. For example what on earth does a "compound radius fingerboard" mean? Shouldn't it be "compound radii" or even "multiple radii"?? Your's confused of Hughenden Valley

Thanks Don, from now one I'm going to refer to my bracing as "barabolic" [/QUOTE]

Good points, all! It should really be 'conical' vs. 'cylindrical' fingerboard, really. Surely the phrase 'compound radius' implies that the radius of the fingerboard, if it has any, is compound, namely a whole composed of different parts? 'Compound Radii' would imply each radius is composed of different parts, which is misleading. Multi-radial fingerboard arching is probably a bit better. Still, 'conical' is concise and accurate. I move to use that one.

Although that brings us back to people asking what equation defines the conical surface the fingerboard represents, and I'm too lazy to dig out the Big Red Book of American Lutherie (volume 3) to look up them details, 'cause dammit Jim, I'm an almost-doctor, not a mathematician!

So, uh, umm...yeah. What were we talking about again?

Perhaps the term asymptotic brace profile would be more accurate - or less inaccurate, where the the sides become more vertical the closer you get to the top, but never achieve full verticality

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now known around here as Pat Foster
_________________
http://www.patfosterguitars.com

Well, life's not perfect and it is perfect like that!

Darn, who said that!

Truth be known, I did not invent the parabola. However, I took out my first ad in "Acoustic Guitar" magazine in the February, 1996 issue, when Parabolic Braceworks was born. Before that... ?

I use parabolas in cross section and lengthwise, although sometimes the latter ends up more like tapered, especially the legs of the X brace. I have found that the cross section is very important in allowing the X brace to release its energy into the top along its entire length. Too narrow a cross section, such as in the drawing above, can make the tone sound harsh, the best word I can find. The slightest irregularities in the sides close to the glue line can hold the energy in the brace. This is especially important in releasing energy to the portions of the soundboard outside of the X's legs.

It is my observation that the braces need to be shaped to gracefully flow with the energy they are delivering or supporting, much like an auto is designed using a wind tunnel. Peaks, corners and ridges all absorb, suck up energy before it can make beautiful sound. That also applies to the bridge, which is a brace, too. Designer bridges with loops and swirls may look cool, but really play hell with the sound, especially the treble. Again, according to my theory, the bridge lies in prime treble generating territory.

If you get a chance to look inside a Martin from the 20's and 30's, you will see perfectly formed back braces, parabolic in length and cross section. A mirror will reveal parabolic side, or finger braces. I saw a 1912 Martin with scalloped X and upper belly brace, but he lower belly brace was half scalloped, with a peak at the end butting against the X, and half parabolic at the bottom end, with no peak. According to my theory, that peak lies in the bass generating part of the soundboard, and that tiny guitar had lots. I was surprised to see that the top was carelessly scratched by sandpaper near the braces. Just workin' in the factory...

Scott

Pat, I like this description, it is very poetic sounding.

Conic works ok, or we could just say a fretboard with variable radius. (until I achieve mucho experience in building, though, I'm sticking with a constant radius of 16")

Ron

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OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

Hi Scott, thanks a lot for the post. I knew some folks were hot-rodding acoustics. I firmly believe that there are good guitars, and then, great guitars, with very little difference in the bracing, but Viva La Differance!

I'm build my son, JP, a guitar, but wanted a knock around guitar for him, he's thirteen. I chose an Ibanez Artwood solid top. It sounded okay at the store, what sold me was the nice sitka top and the fit and finish, pretty nice for a factory guitar for $217. I've bought lots of guitars from this guy.

Well, taking it home and giving it for Christmas, and then getting it alone and comparing it to my handmades, geez, it was pretty flat and tame sounding. I use primarily the Pre-War Martin Scalloped bracing. So, I had a go at this new Ibanez, creating aftermarket scalloping in the xbracing and tone bars. She makes me smile now. Proud to have it in the family.

Son likes it too. Again, thanks for your post, you seem like a really nice fellow.

[QUOTE=old man] Pat, I like this description, it is very poetic sounding.

Conic works ok, or we could just say a fretboard with variable radius. (until I achieve mucho experience in building, though, I'm sticking with a constant radius of 16")

Ron [/QUOTE]

Or, y'know, build a jig like Mario's or John How's, or buy one of Craig Holden's excellent lookin' doodads (if only the shipping costs weren't so massive! This said, I'm earning enough this weekend to pay for one and then some, so I'll be sorely tempted...).

Levelling a compound radius board's really quite easy to do with a flat sanding block. Straight strokes along the surface, few gauges to check progress, and you're good as gold. I'll be making the switch permanently as of the next guitars I build.