Stylus for tracking a stereophonic or quadraphonic sound groove

A method for forming a stylus for tracking the sound groove of a stereophonic or quadraphonic record, comprising the steps of:

• (a) providing a stylus having a longitudinal axis and having a mounting part and a taper,
• (b) forming a pair of convex curved continuous surfaces in said taper which intersect along a continuous arc disposed in both surfaces, said surfaces being dicontinuous relative to each other along the arc of intersection wherealong they form a sharp edge having a substantially constant angle of intersection and being symmetrical about a plane including said longitudinal axis and said arc, said axis passing through the midpoint on said arc where the arc is tangent to a plane normal to said axis, and
• (c) rounding said taper along said sharp edge in a direction normal to said arc with a radius of curvature in the range of 4 to 10 microns wherein, as the stylus tracks the record groove and the actual points that the stylus contacts the groove move around the stylus and define an angle .beta., this angle .beta. is maintained small.