Bracing structure for stringed musical instrument

Abstract

This invention relates to an improved bracing structure for a stringed musical instrument of the type having lower frequency or bass strings and higher frequency or treble strings, and a bridge through which the strings are coupled to a soundboard structure. The bracing structure is formed on the underside of the soundboard and serves both a mechanical-structural and a mechanical-sonic, or acoustical function. The structural function is to protect the soundboard from damage resulting from the torsional forces resulting from the pull of the strings on the bridge, which forces are transmitted through to the soundboard. This function is accomplished by a torsion bar positioned substantially in axial alignment with the bridge, torsional forces applied by strings to the bridge being transmitted through the soundboard to the torsion bar, and a framing bar structure physically connected to and acting through the torsion bar to distribute the torsional forces from the bridge area of the soundboard. These torsional forces may be distributed by the framing bar structure to the elements structurally supporting the soundboard or may be distributed only over a larger area of the soundboard. The sonic or acoustical function is accomplished by a pattern of acoustical bars attached to the underside of the soundboard and oriented in a predetermined pattern which pattern is adapted to permit the soundboard to vibrate optimally at different frequencies in different zones thereof and by a boundary structure which limits the zones of the soundboard which may vibrate at selected frequency ranges and inhibits the formation of antinodes outside of these limited zones. The boundary structure includes, for the preferred embodiments of the invention, peripheral bars generally located at a boundary of the limited zones in which vibration at selected frequencies occur and stiffening bars positioned in regions where vibrations are not to occur.