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Does box ornamentation effect resonance?

Hi guys,

I'm starting a new build, and was thinking of going to town and add brass corners and grommets. The question I have is, does the clutter glued, screwed or bolted to the lid of a box cause a noticeable change in the box's volume?

Also, I get the idea of a sound hole allowing the sound to escape from the box, but any cutting to the box's lid would cause the quality of the resonance to dip. Is there an optimum sound hole size to get the best of both worlds?

(I've added a photo of the box I'll be using, just for a point of reference.)

Cheers

Hedley

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Permalink Reply by BUGGY (C) on August 22, 2012 at 5:05am

Oily send us a link, I always wondered why we had struts and holes. But now finally they make sense after my cheap chineese crappy broken one I got for £15 quid, actually sounded quite good.. so had a peer inside nd low and behold a proper layout of them diagonals under spruce top.

I wouldn't underestimate the use of struts for diffent frequency response people have been perfecting them for years!

But hang on.. what about strings!!! now there's the next research and debate...

maybe the cheap chinese one's arn't the best for tone after all !!

Also seen that blokes carboard acoustic on youtube that works too..

maybe we need to write a specfication for really great CBG build blog...

Spruce top ..??thin , mahogany sides,so big?,rosewood back, ash neck?, martin heavy guage strings,

acoustic stuck on bridge, stuffed with carrier bags inside, Pio capacitor,Cts 500k tone pots,gold foil pickups..... scale?....with so many struts diagonal on underside... he he

or maybe we should just stick with a box and broom handle and shout over the top of it..

Well I have enjoyed this blog and going off the rails, but I am getting closer to understanding the reasons why the damn thing works...so strings next!! ... now where did I put those jazz strings ?

got anything on the resonance of string type and materials....

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Permalink Reply by BUGGY (C) on August 22, 2012 at 5:13am

http://en.wikipedia.org/wiki/Overtone

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Permalink Reply by BUGGY (C) on August 22, 2012 at 5:15am

http://en.wikipedia.org/wiki/Acoustic_resonance

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Permalink Reply by BUGGY (C) on August 22, 2012 at 5:18am

Resonance of a string

Strings under tension, as in instruments such as lutes, harps, guitars, pianos, violins and so forth, have resonant frequencies directly related to the mass, length, and tension of the string. The wavelength that will create the first resonance on the string is equal to twice the length of the string. Higher resonances correspond to wavelengths that are integer divisions of the fundamental wavelength. The corresponding frequencies are related to the speed v of a wave traveling down the string by the equation

$f = {nv \over 2L}$

where L is the length of the string (for a string fixed at both ends) and n = 1, 2, 3... The speed of a wave through a string or wire is related to its tension T and the mass per unit length ρ:

$v = \sqrt {T \over \rho}$

So the frequency is related to the properties of the string by the equation

$f = {n\sqrt {T \over \rho} \over 2 L} = {n\sqrt {T \over m / L} \over 2 L}$

where T is the tension, ρ is the mass per unit length, and m is the total mass.

Higher tension and shorter lengths increase the resonant frequencies. When the string is excited with an impulsive function (a finger pluck or a strike by a hammer), the string vibrates at all the frequencies present in the impulse (an impulsive function theoretically contains 'all' frequencies). Those frequencies that are not one of the resonances are quickly filtered out—they are attenuated—and all that is left is the harmonic vibrations that we hear as a musical note.

String resonance in music instruments

Main article: String resonance (music)

String resonance occurs on string instruments. Strings or parts of strings may resonate at their fundamental or overtone frequencies when other strings are sounded. For example, an A string at 440 Hz will cause an E string at 330 Hz to resonate, because they share an overtone of 1320 Hz (3rd overtone of A and 4th overtone of E).

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Permalink Reply by BUGGY (C) on August 22, 2012 at 5:46am

http://www.alcarruthluthier.com/Downloads/Acoustic1.pdf

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Permalink Reply by BUGGY (C) on August 22, 2012 at 5:53am

This ones above is worth a read through...

Permalink Reply by Bad Finger (Eric) on August 22, 2012 at 5:36am

I swear upon anything holy that after reading 6 pages of dissertations, derivations, calculations, consternations, and confligrations, that I'm going to get a 2x4, some steel wire and hook up a $5 pup to a jack. Then I'm going to wail on it with a beer bottle and fugly old stick.

But my mind can't help but question if mahogany would sound better than pine.

Carry on.

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Permalink Reply by Thomas "Duck" Petry on August 22, 2012 at 7:13am

I'm with ya on that ED (Bad Finger). Post a video of the results. Something to make us Hot Rod Garage Cigar Box Luthiers proud.

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Permalink Reply by Robert Rowe on August 22, 2012 at 7:29am

Doesn't that pretty much describe a Les Paul, Ed?

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Permalink Reply by Bad Finger (Eric) on August 22, 2012 at 7:41am

The Log.

EPISODE 12B'
How to recognize different trees from quite a long way away.
Number 1: The Larch

The larch. The larch.

The discussion here is all good. I've learnt some. Remembered some. And decided I don't give a rat's azz about any of it. I shall build what I build and leave the beautification of sound and sight to others. I'll just takes my chances.

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Permalink Reply by RTZGUITARS on August 22, 2012 at 2:39pm

Let them go Ed it entertains me. Remember in playing and writing less is more.

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Permalink Reply by Bad Finger (Eric) on August 23, 2012 at 2:25am

Oh, yeah. I'd never suggest a limitation on anyone else's dissertation, derivation, calculation, consternation, or conflagration. There is good material in here. And valid even. I just prefer to take more of a Zen approach to this hobby. The guitar builds. The guitar plays. I just get the chance to hold the tools and allow it to take shape.

Some people shudder to think of mass produced, made-in-China CBG knock offs. I have the same feeling for the first time someone breaks out finite elemental analysis and runs a properly controlled and designed experiment on a CBG build. And I'm a formally trained chemist and practically trained engineer. Keep that science stuff out of my roundy, squishy, intuitive, mojo-ish good time.