GB328906A - Improvements in, or relating to, electrical sound reproducing apparatus - Google Patents

Abstract

328,906. Colassi, W. L. April 26, 1929. Magnetic instruments.-A reed type of instrument is characterized by a combined rotary and translational movement of the reed. As described, the reed 5, Figs. 1 and 3, is T-shaped and preferably constructed of tempered silver-steel, the head, which provides a virtual axis of rotation for the stem, being preferably apertured to increase its flexibility and thus allow a bodily up and down movement of the stem. The horseshoe permanent magnet 1 has wide shoulders 2 and straight arms 3, upon one of which is mounted the head of the reed, its ends being supported by steel pillars 6. The stem of the reed extends across to the other arm of the magnet, where its end lies between laminated polepieces 10 and 11, Fig. 2, clamped by a non-magnetic bridge 12. The reed may be mounted independently of the magnet. The normal position of the head of the reed 5 is lower than the surface of the pole-piece 11, and its stem is bent at 5<a> and 5<b> so that its extremity is parallel with the pole-pieces, while if it touched the pole-piece it would do so first with the portion, nearest the axis of rotation. Adjustment of the armature is effected by rotation of a nut 19 on a threaded rod 17 with a square portion 18 passing through a hole in a brass back-plate 4, and connected to a spring 15 attached to the centre of the stem of the reed, preferably by screwing the end 14 into a tapped hole. The driving rod 16 is screwed into the end of the spring 15 which projects through the reed, and vibrations in it are damped by a "tone control " constituted by a bent rod 16a attached to the reed at 5d and engaging the rod 16.