Free Plate Tuning, Part Two: Violins

by Alan Carruth

Originally published in American Lutherie #29, 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 Three: Guitars by Alan Carruth

Before I get into plate tuning proper I’d like to digress a bit and discuss the rationale behind the process, and a couple of other things I find it useful to keep in mind while I’m working. And I can’t think of a better way to begin than by telling you about one of my more elaborate experiments.

Fig. 15 gives the relevant information on my fourth and fifth violins. The idea was to check out the influence of asymmetric back graduations by building a pair of closely-matched fiddles with that as the only variable. The one-piece backs were cut from the same plank of bird’s-eye maple and the tops were cut from a red spruce 4×6 that I took out of the wall of my house when I put in a new chimney. The molds were routed using a template. Archings were checked for height at over two dozen points on each plate and were held to .2MM. Graduation, weight, and frequency data is as shown. The delta f mentioned is the frequency drop obtained when a 5G weight was stuck to the plate in an active area of the given mode. Fittings and so on were matched as closely as possible, and the two bridges were cut back to back from the same piece of maple.

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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.