Free Plate Tuning, Part Three: Guitars

by Alan Carruth

Originally published in American Lutherie #30, 1992 and Big Red Book of American Lutherie Volume Three, 2004

See also,
Free Plate Tuning, Part One: Theory by Alan Carruth
Free Plate Tuning, Part Two: Violins by Alan Carruth



The guitar is somewhat simpler acoustically than the violin, and perhaps more limited. As a result it has evolved into a number of more or less specialized forms to suit different musical uses. It is difficult to imagine a guitar that could “do it all” the way a good violin can. Rather, each guitar seems to have a “center,” a sound that is characteristic of it that suits it for a particular style or player. Good guitars do have a wide dynamic and timbral range, but they always retain their characteristic sound.

As I see it, a good part of the art in this game is deciding where you want the “center” to be, or, alternatively, how to get the “center” you want out of a given shape or set of wood. And then you want to have a broad dynamic and expressive range, good balance, and clarity or resolution; the ability to distinguish things like inner lines. No amount of acoustic science is going to tell you what priority to put on the different characteristics of the sound, nor whether you have succeeded in the end. But if you know what you’re doing, an oscillator and a jar of glitter can help you get the sound you want.

One of the main simplifying factors between the guitar and the violin is the lack of a soundpost in the guitar. This allows the top and the back to be more independent; in acoustic terms they are not so tightly coupled and can act out of phase.