Apparatus for producing sounds of a musical character

摘要

454,720. Electrical musical instruments. MIDGLEY, A. H., and MIDGLEY, A. M., Tudor House, Priory Hill Avenue, Wembley, Middlesex. Feb. 6, 1935, No. 3827. [Class 88 (ii)] In an electrical musical instrument producing oscillations electrostatically, elements of undulating formation, yielding fundamental scale note frequencies which progress geometrically, are carried on a common member. The elements are preferably arranged as concentric rings on a disc, or as circumferential rings on a cylinder, and from a single carrying member two series of scale notes playable from two separate manuals may be obtained. Other members may be provided to supply pure harmonics lying outside the tempered scale, when combining different frequencies in various amplitudes to vary tone. In Fig. 1, the sine-wave rings b charged to the appropriate potentials are connected through small condensers c1 to the grid of the amplifier d feeding the loud-speaker, and co-operate with a rotating arm or arms c connected to earth. A relay rod y pertaining to a note key depresses the contacts g of the fundamental and harmonic rings b of the note, to make contact with contacts g1 connecting the rings, switches q being closed, to bus-bars m energized to the desired potentials by battery x, potentiometer wand resistances u through switches s operated by stop (timbre-control) relayrods t. The sound then continues as long as the key is kept depressed. But if switches k, which with condensers i are in parallel with resistances h, are also closed, a reverberation or sustaining effect is produced after release of the key, the condenser charges gradually leaking away through the resistances h. If the switches k and q are all open, depression of a key disconnects condensers o from the bus-bars m at l, and connects the condensers o to the rings b at n to give a percussion effect. Tremolo is produced by a rotating armature 1. Choke coils f silence the key switch contacts. To enable two separate manuals to be used, the undulations are cut in the middle of the rings, Fig. 3, the inner and outer rings of each pair thus produced forming two sets which are connected to separate amplifiers and loud-speakers. If desired, these two sets of rings may be operated from a single manual, their outputs being connected to a push-pull amplifier. Specification 454,783, describing the same construction is referred to. Specification 380,781 is referred to in the Provisional Specification.