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Single-Scalloped X Bracing?


knockwood
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Was reading about Bourgeois guitars on the Pantheon site yesterday & hit on a passage about Dana Bourgeois' single-scalloped X bracing, which he uses on all of his guitars - in some variation - except OMs. He scallops only the bass side of the top X in order to enhance treble response... Freakin' interesting. I have noticed that in guitars with the kind of big fatass bass I tend to like, the treble does seem to suffer somewhat in clarity... And it would never have occurred to me to ask why the habit of scalloping both segments of the X... Seems simply brilliant, this single-scalloping thing. Has anyone ever heard of this practice anywhere else?

 

Anyone ever played a Bourgeois? I have not. Very, very curious.

 

http://www.pantheonguitars.com

(Click on "Guitar Details" and scroll down. There's a pic of the bracing on one of his dread tops.)

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Honestly I haven't played a Bourgeois, but a good friend of mine goes on and on about the one's he's played. This guy has had a ton of gits and I definitely respect his opinion. Very interesting about the single-sided scalloping.

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Scalloping the bass side of the x-brace should accentuate the bass response. It shouldn't affect the treble much. It's actually much more difficult to coax bass from a guitar than treble. Overbuilt guitars tend to be treble heavy with a kind of "thumpy" bass.

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Originally posted by bjorn-fjord

Scalloping the bass side of the x-brace should accentuate the bass response. It shouldn't affect the treble much. It's actually much more difficult to coax bass from a guitar than treble. Overbuilt guitars tend to be treble heavy with a kind of "thumpy" bass.

 

Last weekend when I was A/B'ing a D-28 & an HD-28, playing them first in that order I noticed immediately that the HD was much louder and more bottom heavy (qualities I generally like), but also that the trebs felt not as clear or well defined as on the D-28. When I read about DB's single-scalloping method, it just turned on a kind of "best of both worlds" lightbulb - seemed like not so much an attempt to coax treble as to not mess with it... Dunno, though. Never touched one.

 

GAS is just horrible. I don't dare go near Mandolin Bros. yet - not enough in the shoebox and I might do something stupid. But I'm dying to try some of the gits I've been reading about.

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I build acoustics on a hobby level and I've found that the best way to enhance bass response is to thin out the periphery of the soundboard. Scallop-braced guitars seem to sacrifice too much trebel response and structural stability compared to thinning out the periphery. You also get more predictabilty and control when you build that way. Also less unpredictable changes as the guitar ages.

 

My theory is that a brace increases in strength 4 times if you double it's height....It only gains 2 times the strength if you double it's width. Good sounding guitars are all about increasing the strength-to-weight ratio of the soundboard. Short answer:

tall and thin braces are good.

 

Scalloping came about during a time when Martin was making smaller guitars and bass was sought after more. Poor recording technology and the abdsence of bass in acoustic bands was the reason. Even Martin tried to get away from it, but tradition and vintage appeal brought it back.

 

I never use it any more. A nice added bonus is that it's less work shaping the soundboard braces.

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Originally posted by guitarcapo

My theory is that a brace increases in strength 4 times if you double it's height....It only gains 2 times the strength if you double it's width. Good sounding guitars are all about increasing the strength-to-weight ratio of the soundboard. Short answer:

tall and thin braces are good.

 

 

That should lend credence to Tacoma's triangular cross-sectional braces shouldn't it?

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Originally posted by guitarcapo

My theory is that a brace increases in strength 4 times if you double it's height....It only gains 2 times the strength if you double it's width. Good sounding guitars are all about increasing the strength-to-weight ratio of the soundboard. Short answer:

tall and thin braces are good.

 

Agreed. Another benefit of tall, thin braces is that they cover less surface area of the soundboard, allowing more of the top to resonate freely. One caution, however, is to make damn sure your brace material was split from a billet and not just sawn out of a piece of "lumber". Grain run-out issues can be greatly exacerbated by thin brace material.

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Hi all, interesting thread about treble on a Bourgeois dread. 

I own two of Dana's dreads, one has double scalloped forward shifted X bracing while the other is double tapered and yet they sound very alike. Santa cruz guitars also build some guitars scalloped and others tapered, the two variations are difficult to tell apart tone wise so the claim goes.

Dana is as mentioned renowned for his asymmetric bracing, mixing tapered with scalloped in my understanding this approach is not so much to enhance the treble response but rather to create a balanced tone which reduces the boomy character you tend to find in lightly built guitars inspired by the pre-war martins. Bass response is the easiest quality to attain in a large bodied guitar such as a dreadnaught due to the large internal volume, it is however not easy to control, an asymmetric bracing pattern goes some way to addressing this undesired effect.

The treble end of both my bourgeois is very fat, totally different to a Martin which tend to be quite thin in that department. As both my guitars from Dana have thick trebles and yet have different bracing the reason for this must lie elsewhere in the build. Other differences in build compared to a Martin are that Bourgeois have thicker top plates that have a much tighter radius, along with a slightly thicker and larger bridge plate, qualities that I suspect may be responsible for the thicker trebles. 

Another point worth mentioning is that although on his asymmetric builds the treble brace is not scalloped it is quite aggressively tapered, not in fact left alone at all. Compared to a tapered braced Martin from the fifties there is no comparison, Martins bracing was not tapered to the same degree. 

My next build will be have asymmetric bracing, a configuration that I haven't yet tried and so I will let you know what the results are.

 

 

 

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