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Solid Body Resonance
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It´s a rather simple, but deep conceptual question. I was unable to find answers at the unversity near me (the teachers just say no, but can´t explain "why" not). It´s the following: (sorry for any typo my english is not so exact but I´m doing my best to improve it.) I had a piece of ash (a kind of wood) and wanna build a solid body guitar from it. One question that comes to mind is: In what shape did I make it? I remember that is, for waves and another things, a ideal resonance space. For sample, in the Shumann Ressonances for sample, there is a "virtual" space created by the earth ionosphere in that some frequencies travel smooth, and also receives a gain (in fact, there is a cavit, a "space", that ressonates with the waves). My question is, this is valid for solid bodys? Can I build a shape of a body that will ressonate with the waves comming from my strings? I know if there is a cavit, a hole, it can be shaped in a way that it reflects and amplificates the sound, but if the waves are travelling in a solid body, can the shape of this body had an influence in the transmission of this waves? I remember the bridge that "ressonate" with the wind (what a cool thing if you weren´t in the bridge lol´s xD), so can I build a shape of solid body of a guitar that makes the sound flows sweet (opps, smooth) from the body itself? In other words, can a specific solid body shape ressonate? Or the shape of the body didn´t influences at all? (eeg, can I build a cubic or a spherical and it didn´t makes any difference). Just remebering that I´m talking about solid body shapes, in the case of a hole or a cavit the things are so different I know. Thanks for anyone for replying. 
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Re: Solid Body Resonance
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by SuicidopoliS
on 2007-11-16 10:44:42 (edited 2007-11-16 10:47:17)
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The big problem here, is that you're willing to build a solid body to resonate the sound created by your guitar strings. The sound waves brought forward by the oscillating strings is pretty weak in amplitude (read: acoustical pressure), so it'll be far from enough the make a solid body made out of wood resonate. Would your sound waves have carried more power, you would've been able to make a piece of wood resonate, sure... Just think of sound being able to destroy windows. Sure enough, no wood, but still a solid body. You'll undoubtedly need a whole lot of power for that though, so this method is useless for building instruments. You'll always need a cavity (i guess) in order to build an instrument, since you'll be willing to work with the sound waves without making them change of propagating medium, thus keeping them "in the air". Once again, the biggest problem you're facing is that you're asking your tiny weeny sound waves, generated by the plucking of your strings, to make a big, solid piece of wood vibrate. This will never work: the sound waves will probably bounce of off your wood for most part, and lose all the rest of their power being absorbed by it (generating heat in the process, not resonating). But then again, i'm no expert in acoustics or lutherie, although i heavily wish i were! .oO° Life's THE CURE, the rest are details! °Oo. |
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Re: Solid Body Resonance
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Thks for all explanation SuicidopoliS. What I can say to you is althougt the small power of the waves comming from the strings, you can be sure that the body does vibrate yes! Of course that isn´t a vibration enough to make the body broken into pieces, sure, but my question is if the shape of this body influences this vibration. Maybe we are at so small measures here, maybe I need a big body to see the hipoteticaly shape-influence variable, but my question is just conceptual, if the shape affects or not the propagation of the waves in the solid body. Anyway, thanks again for your reply. Edit: If I´m saying sh&¨ please ignore it, since I´m not a cientist or a expert or anything. {LoL(i)! xD}
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Re: Solid Body Resonance
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by SuicidopoliS
on 2007-11-16 12:50:21 (edited 2007-11-18 06:45:56)
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As far as i can tell, the shape of your body should absolutely influence the vibration in the body. If it wouldn't, it wouldn't matter soundwise if you made a Piano rectangular, or circular, or the shape it has now, which is obviously in disagreement with real life. Obviously, a Piano is not a plain solid body, there's a lot of empty space in there too, but that doesn't really matter. Air is just a medium through which sound can propagate, as is wood. The shape of your solid body will determine how the vibrations will bounce of the boundaries, which vibration modes will be privileged, will determine differences in stress inside the body, blablabla... This can most easily be "visualized" by thinking of lightbeam that's trapped inside some (partially) reflective body. The shape of this body will clearly influence the way this lightbeam will propagate inside this body, how it will reflect, how many times it will reflect, etc... Although light and sound are very different in nature, they do exhibit likewise behaviour (i'm ignoring the dissipation of sound in the body through mechanical energy here), so i think you can safely deduce that, once again, yes, the shape of your body influences the vibration. This been said, it will not change the starting vibration itself, that one is generated by the plucking of your strings, or whatever else you would do to generate some vibration. What will be influenced, is the way this vibration is sustained. PS: i would like to stress again that i am absolutely no expert in this field, and that this is only my opinion on the subject. Don't take my words to be the ultimate truth, and don't go insulting your professors saying i told you they are wrong! .oO° Life's THE CURE, the rest are details! °Oo. |
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Re: Solid Body Resonance
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LOL!!! Thanks for more explanation. Your analogy with the beamligth helps a lot, really a good way to think. And be calm, in fact I already give up from the professors... it´s better to leave them alone... xD
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Re: Solid Body Resonance
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as in a solid bodied electric guitar? air has little/nothing to do with solid bodied guitars. you cant amplify the sound of your strings from a solid bodied guitar, you need pick ups for that. shape can influence an acoustic guitar's sound but not so much for solid bodied ones(although it does affect resonance, i think. but still, its not the body that amplifies the vibrations from the strings.). the different styles, sounds and feels that solid bodied guitars create has a lot more to do with their pick-ups and strings plus amps, gadgets and mixing than it's shape. you can take an epiphone/gibson sg design, prep it with b.c. rich or warwick interior and pick-ups, wire it to peavey amps, line it with d'addario strings and it wont sound anything like a gibson. maybe a guitar body's density would have more effect than it's shape(if ever a guitar's body can affect it's pick-ups which i doubt it can.) ex. ashwood, mahogany, maple etc.. or at least thats what other guitarists say. i always think of my guitar body's shape as serving a guitar's aesthetic purposes along with it's color and head shape. i think of it as i would a woman's body. simply put, a pretty lady with curves you'd die for doesnt necessarily mean she has a gorgeous voice and not all fat ladies can sing.
love & peace
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Re: Solid Body Resonance
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by EricStillLazy
on 2007-12-21 17:47:33
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OK I am coming from experience in building speakers and their enclosures, and some experience in building a banjo. There should be NO noticeable affect in the design of a solid body in terms of a guitar. The reason in which the shape of a acoustic guitar can influence the sound is because the sound waves bounce around inside the body resonating, and the shape determines which frequencies are resonated (is that a word?) louder and which ones get stifled out. The strings on the body might cause vibration in the body of your guitar, but they wont "bounce" around and resonate, THUS it is safe in assuming that a solid body guitars sound is not influenced by its shape. In example, Princes symbol guitar sounds just as amazing as any other guitar he rocks out on. Btw.. im back
WHOOOOOOOOOOO
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Re: Solid Body Resonance
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by SuicidopoliS
on 2007-12-22 02:57:24
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In example, Princes symbol guitar sounds just as amazing as any other guitar he rocks out on. It sure as hell does, BUT those are electric guitars, so he uses pick-up elements to capture the vibrations of the strings. It is obvious that the vibrations picked up by these elements will be much bigger than any possible solid body resonance created by the small vibration of the strings, thus i agree that we can safely ignore the shape of the solid body part for the sound of these guitars. But that wasn't the question, the question was simply if the shape of the body would or would not influence the propagation of the vibration caused inside this body by the humming of the strings, and i still stick to my previous answer that indeed it will, even if i also agree that you (expect maybe for some marginal case) won't notice this soundwise. .oO° Life's THE CURE, the rest are details! °Oo. |
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Re: Solid Body Resonance
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by EricStillLazy
on 2007-12-22 09:51:54
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Well I dont have much experience in guitars or their design, and when I read solid body I assumed an electric guitar and not an acoustic. As by acoutic guitars produce thier sound by resonating sound waves inside the body to a level someone could hear them. I couldnt think of a string instrutment that doesnt use some kinda open space to resonate sound waves and no electronic pickups.
WHOOOOOOOOOOO
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Re: Solid Body Resonance
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"I couldnt think of a string instrutment that doesnt use some kinda open space to resonate sound waves and no electronic pickups." ^same with me. although it can, but only quite unnoticeable to hear. SuicidopoliS answered the question entirely i guess. "But that wasn't the question, the question was simply if the shape of the body would or would not influence the propagation of the vibration caused inside this body by the humming of the strings, and i still stick to my previous answer that indeed it will, even if i also agree that you (expect maybe for some marginal case) won't notice this soundwise." this question actually made me realize something. what if someone comes up with a type of pickup that actually picks up vibrations from the body like a microphone or something then amplifies it? i wonder what the approriate shape for each genre would be like.
love & peace
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Re: Solid Body Resonance
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by SuicidopoliS
on 2008-01-02 15:15:42
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this question actually made me realize something. what if someone comes up with a type of pickup that actually picks up vibrations from the body like a microphone or something then amplifies it? i wonder what the approriate shape for each genre would be like. That's pretty much the idea behind piezoelectric transducers, which are sometimes used to pick up sound produced by guitar bodies (although only the acoustical ones), piano's (plugged to the metal frame), upright basses, etc... .oO° Life's THE CURE, the rest are details! °Oo. |