Articles, Blog

Guitar Body

November 7, 2019

Now this is about the mechanics of the
guitar body. It will have to be mostly links to more
informed sources. About everything here is either too
technical or a trade secret or controversial or subject to copyright. The links
themselves will be under the words “Show More” down below here and also on sites.fretmath. This is one of the few images I can use.
And here on this close up I drew in the nodal lines or chladni lines, these are the points of no vibration. This is on a drum surface. Here is the derivation and the modifications
that I made. And here again are the lower modes of the soundboard. They are poles, meaning they move in opposite
directions. And vibrations are measured in microns which are extremely small. Your nodal lines or chladni lines are points
of no vibration. And here are the chladni or nodal lines of the back plate of an acoustic guitar. The solid-body electric also has
vibration patterns and bending modes. The set of links follows will
probably be the best introduction for both acoustic and electric. Both are these university professors are
also musicians. The visual imagery here will give a
quick introduction to anyone. And now both of these sites are primarily for science and engineering types, if you don’t find yourself to be in one
of those categories just look them over, see what you can use and
leave the rest. This is a PDF of a short, rather
non-technical talk given by Bernard Richardson in 2010. And this gives a direct link to a short,
oh!, five minutes or so section of longer discussion. I think everything
here actually was well-prepared except for the Blackbird introduction. Now these provide the best and most
colourful images but there’s no discussion so I leave all the criticism and
evaluation to others. Acoustics for Violin and Guitar Makers
by Janssen is for luthiers and reasonably
accessible. Below that are some abstracts from a
recent acoustics conference in you can see what
the scientists have been up to. Mainly it seems, replacing us with mobile
app’s. This is a short video on the restoration
of the most important of the classical guitars. The restorer here notes that the complex
structure of Harmonics is probably more elusive than the sciences have yet discovered. I would agree with him on
that. Coupling indicates how the energy is
transferred from the string to the sound wave. And there are compromises to be made,
what helps one thing will hurt another Now this is to give at least some idea
of how an enclosed a body of air might vibrate in one of its modes. I experiment a little here on how a soundboard might be affected by such a pattern. Keep in mind, the sound board is a driven
primarily by the strings so this might be totally wrong. In any event here is the derivation and
the modifications that I made. Jim Woodhouse is an expert here, he’s
also been building guitars and other instruments since he was 14. These are two pretty technical
papers probably not for the average guitarist. Juan Fernandez-M is also a scientist and
amateur guitar builder. He’s a little bit more accessible here. I had created this image earlier for
one the other videos. From what I can research here and read
here maybe for an acoustic you would want it a little bit rougher a little
bit more like the upper image for an electric probably a little bit smoother like the lower image. I can’t be certain this is really all
more, more a matter for other more experienced
expert people than me.


  • Reply Fretmath March 23, 2015 at 11:32 am

    General mechanics of the guitar. There is not much I can do here and this is primarily a set of links to better sources. It seems necessary for the series to have something here and this is at least an exercise in copyright usage. No one can know everything about anything and we will have to find a way to share our knowledge as best we can. Creative Commons intends clarity, we shall see.

  • Reply John Platko April 15, 2015 at 3:36 pm

    I see you gave a pointer to some FEA analysis of guitar modes I made some time ago. If you feel the need for discussion of those "colorful" videos, I'll be happy to respond as best I can.

  • Leave a Reply