GB247995A - Improvements in the construction of sound-boards for stringed musical instruments - Google Patents

Abstract

247,995. Lumiere, L. Feb. 21, 1925, [Convention date]. Pianofortes and other stringed instruments, soundboards and bridges for; violins. - The formation of nodal lines in vibrating soundboards of stringed instruments is avoided by constructing the soundboard with uniform resistance to the strains transmitted by the bridge, its thickness increasing from the edges to the point or points of support of the bridge in accordance with a hyperbolic law. In a violin as shown in Figs. 1 and 3, the hyperbolic curves of thickness h radiate from the left foot p of the bridge and have a common asymptote passing through that foot. The back is similarly formed, the right foot of the bridge being extended as at v and passing freely through the belly so as to rest on the back in the position of the common asymptote. The boards may be built up of superposed sheets, indicated by dotted lines in Figs. 1 and 7, glued together and arranged so that their edges lie in the hyperbolic curves. These sheets may have tongues t as shown in Fig. 7 to give a more continuous elastic reaction. The sound holes of the violin may be placed in the sides of the bouts. In the case of a mandolin, Fig. 8, where the whole of the base of the bridge contacts with the belly, the hyperbolic curves radiate only from the ends of the bridge, being arranged parallel from m' to m<9>. In a pianoforte soundboard, Fig. 12, the curves are arranged parallel, approximately at right angles to the bridge f, which is formed by the thickness of the board intervening between the ends of the pairs of curves and may varv in width. This soundboard may also be formed of sheets with serrated edges. A modification of the previous constructions consists in arranging edge on, on a board of uniform thickness, a number of hyperbolic strips h', either parallel and perpendicular to a bridge f as shown in Fig. 17, or radiating from a common asymptote.