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| Crazy question about bracing... http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=5343 |
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| Author: | John Elshaw [ Mon Feb 27, 2006 5:45 am ] |
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If it were possible to wait until a top was attached to see how you would brace it, what approach would you take? For example, once the top was on, if you could vibrate the top and use the sand method to figure out where everything was moving, would you change your bracing pattern to fit in certain spots depending on where the top was/wasn't active? Aside from the strength that braces add, what's the theory as to how to decide where the braces should go for sound management? Let's assume we're in an ideal world where you could visually see everywhere the top is vibrating before you brace it. Cheers! John |
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| Author: | Alan Carruth [ Mon Feb 27, 2006 6:14 am ] |
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I think there are probably books about this.... ;) Bracing does three things that I can think of: 1) It adds enough static stiffness to keep the top from folding up under the string tension, without adding too much weight. 2) It sets up the ratio of long-grain to cross-grain stiffness that seems to establish the basic timbre of the top. 3) It controls the symmetry of the top, and establishes the way it will 'break up' into smaller vibrating areas at higher frequencies. This seems in some part to ditates how 'good' the guitar will be, given the limits of the basic timbre. For example: if you use a Torres style fan to brace the top you will most lilely end up with a basic timbre that will be suitable for a classical guitar with nylon or gut strings. With steel strings, assuming the bracing and top thickness are sufficient to hold up well, the timbre is likely to be sort of 'bluesy'. We all know from trips to Wal-Mart that it's perfectly possible to make a guitar with Torres style bracing that sounds really bad: all you need to do is make the bracing too heavy and stick it on with gobs of hot-melt glue, or whatever it is that they're using in those factories these days. Even with good wood those boxes would not be very good sounding with the bracing so screwed up. A few heavy braces can yeild the same stiffness and stiffness ratio as a lot of smaller ones, but the top will break up acoustically differently, and have a different tone. Usually the 'smoother' the stiffness distribution, and the fewer big 'lumps', the more even and 'interesting' the tone will be, or so it seems to me. Remember: all categorical statements are false, including this one. We could go 'round and 'round for sveral weeks on symmetry and not come to any agreement. Some poeple like it, some don't. Chacun a son gout. In an experiment such as you suggest (which sounds like fun!) I strongly suspect that the placement of the first brace or two would strongly influence the 'best' placement of the next one, and so on. You would probably be able to start with almost anything and make it work pretty well with a bit of effort, but starting out even a little differently would most likely end up with a substantially different 'best' bracing scheme. With enough experiments of this sort you might well be able to derive some general rules about what constitutes a 'good' guitar, and that would certainly be a useful thing to do. One shudders to think of the effort involved, though. NOTHING takes longer than science. |
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| Author: | jfrench [ Mon Feb 27, 2006 6:14 am ] |
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Jose Ramirez III did something similar, and said he told several guitarists about it and he was so excited about it that he'd never built a guitar faster in his life. Of course, he probably personally built less than 8 guitars in his life anyway, but he'd overseen enough guitar making to have a good idea. The outcome was that it was no better and no worse than any other guitar coming out of the Ramirez shop. To him (as paraphrased from his essays contained in "Things About the Guitar") the experiment was a total failure in that he didn't learn a single thing from it. I'm definitely not saying this isn't worth a shot. But I also don't think braces necessarily get in the way of the sound. |
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| Author: | John Elshaw [ Mon Feb 27, 2006 7:03 am ] |
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One of the reasons I started thinking about this was from the freeware program linked here: Guitar soundwave It's just a program that emulates a soundwave being bounced around in a guitar box. It doesn't take into account braces, nor is it supposed to be used for anything other than to stimulate thinking. But it would be neat if you could build a guitar and then brace it afterwards (maybe you could use the back as a mini go-bar deck to do this). Al -- good point about earlier bracing affecting placement of later braces. No doubt you are right and that would be a big factor. I wonder if there is a way to build a removable top (or at least less permanantly attached) so this could be tested over and over with many configurations? Hmm... |
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| Author: | CarltonM [ Mon Feb 27, 2006 7:28 am ] |
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[QUOTE=Alan Carruth] I strongly suspect that the placement of the first brace or two would strongly influence the 'best' placement of the next one, and so on. ...One shudders to think of the effort involved, though. NOTHING takes longer than science. [/QUOTE] Didn't Michael Kasha and Richard Schneider take an approach similar to this? They tweaked something in every instrument Schneider built. Unfortunately for the lutherie world, Richard died before they reached a point where they could consider it "done". He still built some masterfully superior guitars, though. It doesn't seem like anyone else is working as closely with Dr. Kasha now, and I think that's too bad. |
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