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Thoughts on Soundboard Vibration

Thoughts on Soundboard Vibration

by Paul Wyszkowski

Originally published as Guild of American Luthiers Data Sheet #200, 1981



The classic guitar, like the harp but unlike the violin, the mandolin or the zither, has its strings attached directly to the soundboard. In the case of a violin, it is pretty clear that the bridge communicates primarily vibrations which are perpendicular to the surface of the soundboard. But it is not so obvious how the strings of a guitar transmit their vibration to the soundboard. However, a few minutes’ thought and a simple experiment can settle that question.

Back in 1954, J.K. Sutcliffe stated in an article in Guitar News that the fundamental action linking the string to the soundboard is the rocking of the bridge in response to the longitudinal (along the length) vibrations of the string. That is, the front and back edges of the bridge rise and fall as the string becomes tighter and looser (see Fig. 1). Later, Michael Kasha used this idea in his theory of guitar design. As a consequence, this view was accepted by many luthiers as correct.

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The Power of Circles

The Power of Circles

by Michael Darnton

from his 2004 GAL Convention lecture

Originally published in American Lutherie #87, 2006



Violins and guitars that are strong visually have a solid underlying structure that you might not see if you’re just casually looking. But it’s there. Designers of the past constructed a shape with straightedge and compass on concrete geometric forms.

There are many equally valid ways to look at designs, but I hope everyone will at least consider the concept that I’m going to talk about today: that strong instrument design comes most easily from the consistent use of very simple geometric shapes. This doesn’t eliminate creativity and new forms. Rather, it can strengthen the impact of any design, traditional or modern, by drawing on a common language to promote immediate visual understanding, usually on a subconscious, but effective, level.

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Geometric Design of the Stradivari Model G Violin, Part One: Mold and Template

Geometric Design of the Stradivari Model G Violin, Part One: Mold and Template

by Robert J. Spear

Originally published in American Lutherie #93, 2008

see also,
Geometric Design of the Stradivari Model G Violin, Part Two: f-holes by Robert J. Spear
Geometric Design of the Stradivari Model G Violin, Part Three: The Scroll by Robert J. Spear



I have little doubt that artists, artisans, and architects of the Renaissance and Baroque used some system of guidance for their drawings that was based on the knowledge of geometry and the use of straightedge and divider. I began my drawing adventure almost five years ago by following the guidelines for the geometric design of the Model G in Sacconi’s book and soon discovered errors. Even so, I was convinced that it would be worthwhile to use a classical Cremonese approach based on geometry because I wanted to see if I could integrate it with Hutchins and Schelleng’s scaling theories used for the New Violin Family. While the acoustical aspects of the exercise are not germane here, I worked to realize a design system that would essentially produce a second generation of octet instruments close to a classical Cremonese violin in the style of the Model G Stradivari. My goal was to impart a greater uniformity to the octet family’s models, but to keep this article within bounds I have confined my remarks to the violin.

There are those who question whether geometric design really played an important role in violin design and suggest that the model outline could be designed freehand. Others allow that some sort of geometrical or proportion scheme was used, but that it was not based on the golden section. A few ask why one can’t just get a good photo of a good model and enlarge or reduce it at the local copy center. You can (and I did at first), but because strange things start to happen in the larger and smaller instruments during the scaling process, straight scaling does not hold up. Still others, including Sacconi, stress that the eye was the final arbiter of any design, no matter how it was derived. I will attempt to address all of these points in this series of articles.

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Geometric Design of the Stradivari Model G Violin, Part Two: f-Holes

Geometric Design of the Stradivari Model G Violin, Part Two: f-Holes

with Robert J. Spear

Originally published in American Lutherie #94, 2008

see also,
Geometric Design of the Stradivari Model G Violin, Part One: Mold and Template by Robert J. Spear
Geometric Design of the Stradivari Model G Violin, Part Three: The Scroll by Robert J. Spear



The Cremonese design for the f-holes of a violin, at first glance, would appear to be based on the same design philosophy as the body and to make extensive use of the golden section. A. Thomas King, in his article “The Cremonese System for Positioning the f-Holes” in The Strad, shows rather convincingly that golden-section divisions based on the distance between the pins on the body was employed to fix the location of the f-hole eyes, which further reinforces this idea. However, when it comes to f-holes, I would like to suggest that there are a couple of additional jokers in the deck. First, the late Cremonese f-hole is derived from an earlier system of design, and some of the important parts of the predecessor system remain in use; second, an entirely different modulus is used for the f-holes than for the body; and, third, little is based on the golden section.

The Forma G violin, upon which my model is based, is not quite the longest violin Stradivari ever made, but it is the widest. The most notable increase in width is in the center bout, which has another direct impact on the design of the f-hole and its placement. King notes that there is a general method for most Cremonese violins and a specialized adaptation for Stradivari violins. King explained the rather unintuitive step of taking the golden section of the distance between the locating pins in the top as the modulus for positioning the f-holes. I have used his approach here because it has many good points of correlation, and because I found an additional correlation that has convinced me even further that his hypothesis is correct.

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Geometric Design of the Stradivari Model G Violin, Part Three: The Scroll

Geometric Design of the Stradivari Model G Violin, Part Three: The Scroll

with Robert J. Spear

Originally published in American Lutherie #95, 2008

see also,
Geometric Design of the Stradivari Model G Violin, Part One: Mold and Template by Robert J. Spear
Geometric Design of the Stradivari Model G Violin, Part Two: f-holes by Robert J. Spear



Scrolls are all about spirals, and in mathematics only two kinds of spirals exist: the Archimedean and the logarithmic. The Archimedean is considered a special case because it is the only spiral where the expansion of each complete turn is identical in dimension to the one before or after it. A commonly used example is that of a tightly coiled garden hose laid on a flat surface. All other spirals, including golden-section spirals, are logarithmic. Although the actual distance between turns of log spirals is not uniform, the rate of expansion remains constant.

To the Renaissance geometer and artisan, spirals were a natural form of great beauty and inspiration. A spiral played with the viewer’s visual senses, leading his eye on a merry chase and fooling it with the subtle shifting of its expansion. In modern times, the execution of the scroll is considered one of the few remaining places on the violin where the craftsman can display individuality, originality, and skill — and sometimes even all of these together!

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