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Andy Powers Replies to my V-bracing Question
I wanted to make sure I understood the intonation issue that the V-bracing addresses so I asked Taylor Guitars:
Very soon after, Andy Powers was kind enough to send me a reply which I’m posting with his permission: Totally ignoring the string compensation parameter of intonation, we'll think only in terms of resonance and vibration for a minute or two. A guitar body amplifies string sound by functioning as a coupled resonator. The string vibrates at a pitch and is attached to the body, transferring its vibration to a larger surface which will try to vibrate at the same frequency. If the body were so tuned to vibrate at exactly the same frequency as the string, life would be great. However, along with the intended fundamental note, we have overtones, and to a weaker degree, undertones. These are mathematically related other pitches summed together with the intended pitch. If we looked at A 110Hz, we should also have 220 Hz, 330Hz and so on, as well as a half-formed 55Hz. Now, in order to replicate this, a guitar body would need to respond to all of these, at exact frequencies. Last edited by Herb Hunter; 03-07-2018 at 05:45 PM. |
#2
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The video below illustrates Chladni patterns.
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#3
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I really appreciate Andy’s extensive response and I thank you for asking permission to post it here. But a lot of what Andy writes does not make sense. Such as “undertones” at half the fundamental frequency of a string. Never heard of or read about them.
If I find time I might elaborate on Andy’s story and pinpoint the flaws. On the other hand, I might as well not.
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Last edited by Acousticado; 03-07-2018 at 06:38 PM. Reason: Rule #1 |
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How beautifully and clearly written. Thank you VERY much for sharing!
I can now rationalize (justify?) upgrading my 2011 914CE to current because my Chladni patterns are too chaotic... Hell YES!
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------------------ 1986 Yairi/Alvarez FY65 2011 Taylor 914CE 2016 Taylor 712e 12-fret 2014 Breedlove Parlor Line 6 L2T |
#5
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I’m not too interested in the physics of this, but skimming over Andy’s reply I get a strong sense he’s interested in what he’s doing (integrity), even if it may not fall in line strictly with physics terminology/classification.
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#6
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I would think you would want something symmetrical under the top like an x brace to interfere as little as possible with the vibrational top modes. Seems like a v brace would interfere with some of these modes.
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#7
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Quote:
Andy's point about boxes having best-frequency resonance characteristics that lie between the tuned string frequencies (rather than perfectly harmonized to them) is absolutely true and that has always been the builder's conundrum. Looks great but is it a good string frequency generator? K&K PWM SBTs were designed for that reason but they did not go far enough. They should have provided longer leads for each of the three transducers to allow the installer to find the hottest spots on the underside of the top for each of the frequency ranges. But, that would have created a problem with the device as a DIY product so it is what it is. Last edited by Acousticado; 03-07-2018 at 06:39 PM. Reason: Edited quote |
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Ok, I'm pretty well smoked on all this - - -
Not clicking on any more Taylor/Andy Powers posts for the foreseeable future Last edited by Montesdad; 03-07-2018 at 11:36 PM. |
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Quote:
I’m not willing to categorically state something doesn’t make sense merely because I’ve never heard the term before. The most I might say is it doesn’t make sense to me given my lack of familiarity. I assume that by undertones, Andy is referring to a subharmonics. Last edited by Acousticado; 03-07-2018 at 06:39 PM. Reason: Edited quote |
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Quote:
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Something something, beer is good, and people are crazy. Last edited by Acousticado; 03-07-2018 at 06:39 PM. Reason: Edited quote |
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Interesting info here. Please tread carefully.
__________________
Tom '21 Martin D-18 Standard | '02 Taylor 814c | '18 Taylor 214ceDLX | '18 Taylor 150e-12 | '78 Ibanez Dread (First acoustic) | '08 CA Cargo | '02 Fender Strat American '57 RI My original songs Last edited by Acousticado; 03-07-2018 at 06:34 PM. |
#12
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With all the stuff written about this, what really matters to me is how it sounds.
No diagrams, equations or scientific evidence necessary. |
#13
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Ultimately, that is what matters but to the technically inclined, the mechanics and science behind any innovation can be fascinating.
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Quote:
Last edited by frankmcr; 03-07-2018 at 07:59 PM. |
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I found it useful and interesting to read. Thanks for asking and posting. I think you've added substantively to the conversation.
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