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Question on Bracings
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=23727		 Page 1 of 1
Author:  Keiji [ Mon Sep 07, 2009 9:47 pm ]
Post subject:  Question on Bracings
Hey guys... im doing a research paper on the different types of bracings and woods on acoustic guitars and i was wondering if anyone can help.

My question is what are some of the bracings you can put on a guitar and how does it affect the sound of the guitar? it can be on any type of acoustic guitars. im looking for any to all types of bracings, from the popular commons ones we use today such as the X-bracings, to the most uncommon ones such as the Kasha bracing or Samo Sali bracing. Im seeing how each brace affects the sound, whether it gives a lower/higher tone, etc.
I can also look at bracings that anyone one of you have designed using analytic processes based on physics.

Im also looking for ones from other countries and cultures, and what different styles of music use commonly, such as jazz and the use of 2 parallel braces. Im also looking for ones from other time periods too... such as the use of Fan bracings.

Im also looking on how different types of woods can affect the sound.

Any help is greatly appreciated. Thanks in advance. :)
Author:  Christian Schmid [ Mon Sep 07, 2009 11:25 pm ]
Post subject:  Re: Question on Bracings
I won't be of much help as I really lack the experience. But once your paper is done, please send me a copy [:Y:]

Anyways - it's probably hard to answer, because sound does not easily translate into words. If I was to say that bracing A sounds warmer, fuller, and more complex, whereas bracing B sounds tighter, more direct, and less complex... what does that actually mean? And would another person use the same words?

Anyways, here are some resources:

Since you're also interested in the effect of tonewoods, here are some descriptions and diagrams from Breedlove guitars: Again - keep in mind, that this is only one way to describe it.

http://www.breedloveguitars.com/instruments/guitars/custom_shop/original/tonewoods.php

Next are some resources about acoustics/guitar acoustics:
http://www.speech.kth.se/music/acviguit4/
http://www.phys.unsw.edu.au/music/guitar/

Hope that helps,
Christian
Author:  Alan Carruth [ Wed Sep 09, 2009 12:53 pm ]
Post subject:  Re: Question on Bracings
" Im seeing how each brace affects the sound, whether it gives a lower/higher tone, etc.
[snip]
Im also looking on how different types of woods can affect the sound."

You need to narrow your focus. That's why you don't have many replies here: the questions as you've stated them are about impossible to answer.

As has been said: "the sound is in the top". all of the studies I've seen that looked into this have shown that bracing is, at best, a fine-tuning mechanism. Not that that's trivial; however, it does set some pretty tight limits on how important any one brace can be. What seems to count, IMO, is the overall distribution of stiffness and mass within the top, and, in particular, how the bracing and the top work, or don't work, together. If the entire assembly is 'loose' it's likely to sound 'flabby', and so on, but you could get that from a thin top with 'normal' bracing, or a thicker top with light bracing. The details of the timbre will vary, of course, in these two cases. But there are lots of different brace patterns that will yeild an acceptible mass and stiffness distribution, and the choice of which one to use is generally a matter of taste as to the details of the tone they produce.

If you look up in the 'Double X brace' thread, you'll see that I talk about a 'matched pair' experiment I did. There were subtle, but clear, differences in the tone of those two guitars, but they would be difficult to characterize as 'lower/higher tone' or whatever. I once built a 'tonal copy' of a specific old Martin that was successful despite the fact that the top bracing was very little like anything Martin ever used. In something as complex as a guitar top, there are lots of ways to get to the same destination.
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