The objective set for the final composite model are that the guitar has better resonance ( a longer tone) and a more mellow timbre (tone quality). In order to complete the first of these two criteria a high modulus material is desired that is as thin as possible without sacrificing the structural integrity of the soundboard as whole. In other words it is necessary that it can resist warping from the tension of the strings as well as under conditions such as changes in temperature. The soundboard is attached with a glue adhesive, thus the resin must have a melting point higher than the glue used to attach the board so that it can be removed and replaced.
The motivation for using a high modulus material arises from the fact that the greatest interruption to the acoustic resonance of the sound emitted from the guitar comes from the wooden ribbing that holds a convectional wooden soundboard in to place. The material itself does much less to effect the guitars sustain, although it can influence its timbre, or tonal quality (i.e. mellow, metallic, poignant).
The guitar being used is a Yamaha C-40 classical acoustic guitar. It features a traditional spruce soundboard with inner ribbing.
A carbon fiber-epoxy resin composite is the material of choice for this task.
