“Damping” is the phenomenon of absorbing or diffusing vibrations in an acoustical system. For example, if you put a piece of tape on a bell, it will damp the vibrations of the bell; in essence, it reduces its volume, alters its tone color (“timbre”), and limits its sustain.
Many guitar and banjo players have noticed that their instruments have greater sustain and timbre when they clip a capo to the peghead. Similar results come from stiffer, denser neck woods and the use of heavier tuning machines. The added mass to the neck and at the peghead inhibits the damping and improves both sustain and timbre. Heavier truss rod systems also contribute to greater sustain and improved timbre.
The study of inhibiting damping is not new. The early makers of viol family instruments understood the problems associated with damping, and their effort to minimize damping is demonstrated by the mass of the scroll at the peghead, extended ebony fretboards, and the addition of mass or stiffeners to the ends of thin soundboard areas, especially at the f-holes.
While working at Gibson, Lloyd Loar attempted to apply the lessons from of great violin makers to the construction of the Master Model instruments (F5 mandolin, H5 mandola, K5 mando-cello, and L5 guitar). To this end, he focused on adopting seven important structural features that included:
1) A string break angle (angle the strings make over the bridge) of 16°.
2) The use of longitudinal tone bars that emulated the singular bass bar of the viol family instruments.
3) Stiffening the edges of the soundholes by applying gauze around the inside of the f-holes.
4) Adding mass to the unsupported end of the fretboard by the use of an ebony fretboard extender.
5) Arched and graduated soundboard and backboard.
6) The use of f-holes rather than round or oval apertures.
7) A tuned air chamber, soundboard, and backboard.
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Want more information? Please email us, or write to Siminoff Banjo and Mandolin Parts, PO box 2992, Atascadero, CA 93423, USA, or you may call us at 805.365.7111, Monday-Friday, 8:30am to 4:30pm (we are on Pacific Time).