GB313764A - Improvements in and relating to sound reproducing instruments - Google Patents

Abstract

313,764. Lassman, H. H. June 27, 1928. Magnetic instruments.-The magnetic system of a sound reproducing instrument comprises a plurality of bar magnets c at one end of which are mounted pole pieces d, e built up of E-shaped laminations and arranged to form an air gap j. The pole-pieces are held in position on be magnets by a clamping strap g. One end of the lower limb l of a forked reed is located within the air gap, the extremity of the upper limb o lying above the upper pole-piece. The forked reed o. l is polarized through the intermediary of a supporting standard k which is mounted at the other end of the bar magnets. In a modification, the upper portion o of the reed may be separate from the lower portion, the two being clamped together on the standard. The two portions are joined by a rod p in order that the vibrations of the lower limb may be transferred to the upper portion and adjustment of the composite reed is effected by a spring m under the control of a knob n. The two portions of the reed may be of different thicknesses in order to respond to high and low frequencies. The vibrations of the reed are conveyed to the sound reproducing diaphragm by a connecting, rod having a plurality of portions of different diameter. As shown, the connecting rod has portions r, q of different diameter, the larger portion being secured to the upper portion of the reed. The magnetic system is supported on a base plate a of insulating material having an insulating cover b. If desired, the magnetic system shown may be duplicated.