Measurable Characteristics of Violin-Family Instruments in Relation to the Sound of a High-Quality Violin
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that can be used for various violin-family instruments, depending on size. When a flitch is properly cut and joined for a violin top, the annual-ring spacing, or grain, ideally should be narrow in the center of the violin top, gradually becoming wider toward the edges. Also, the grain should be vertical to the bottom surface of the top plate. The more researchers study the desirable parameters of spruce for the proper tuning of violin top and back free plates and the effects they have on the finished instrument, the more the seemingly unsupported lore of violin making makes very good Young's Modulus It has been shown that the desirable ratio of Young's modulus along the grain to Young's modulus across the grain in spruce for violin tops is about 10:1, and in the curly maple for violin backs, about 5:3. Tests have shown, however, that if the grain of a spruce top is 90 degrees to the flat, rather than the traditional 180 degrees, Young's modulus becomes nearly 100:1, and the piece will not make a good instrument. Also, spruce trees in the mountains tend to grow more slowly as they get older, making the later growth rings narrower. Therefore, the joined violin tops will have narrower grains in the center and wider grains toward the edges, which makes for better plate tuning.
Introduction The extreme variations in the mechanical as well as acoustical properties of wood, not only within a given species, but even within the same tree, have plagued violin researchers for nearly 100 years and violin makers for more than 300 years. The lore of violin making tells us that a spruce tree growing on the north side of a mountain should be cut in
the spring when the water is moving up in the wood cells, and that the first six or eight feet of the trunk should be discarded because the twisting and the weight of the big trunk cause increased density in the wood with a less even grain structure. The wood should then be cut into lengths, free of knots and sap cracks, and split into so-called flitches
Structure The tradition of naturally seasoning violin top wood for 10-20 years and back wood for 20-50 years with no kiln drying is being better understood as wood testing becomes more sophisticated and we learn that, as wood ages, the ratio of
Mode #1
Mode #2
Mode #5
Figure 1. The top and back free plates of a violin just before assembly, showing the nodal areas of modes #1, #2, and#5. These patterns are produced by mounting a top or back plate as a dish and sprinkling it with black aluminum flake over a loudspeaker activated with a swept sine wave. When the sine-wave frequency matches that of a plate's normal mode, the particles bounce into its nodal areas. (Photographs courtesy of Chris Maynard.)
MRS BULLETIN/MARCH 1995
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Measurable Characteristics of Violin-Family Instruments in Relation to Sound
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