Abstract: A multiple-stage active RC distributed filter having multiple inputs and a single output for producing filtering of large groups of notes for tone coloration in electronic musical instruments. Output signals from the keying circuits may be applied to selected input stages of the filter through a resistor matrix to produce the desired tone coloration. Voicing may be further modified by one or more compensation networks at the filter output.

Abstract: A sound reflector for use with a grand piano to reflect sound from the underside of the soundboard toward the rear side of the instrument, the reflector comprising a large panel of sound reflective material underlying the soundboard at an inclined angle with its uppermost side edges adjacent the undersurface of the front side wall of the instrument and with its lowermost side edge at floor level; the reflective panel may be planar or its sound reflecting surface may be convex in cross-section in one or more directions; brackets may be provided to detachably mount the panel to the front side wall of the case or the panel may be permanently attached to the case, as by means of hinges; and means may be provided to suspend the panel so that its lowermost side edge will clear the floor when the piano is moved.