Improvements relating to the control of swell-chambers, crescendo-boxes and the like

摘要

478,287. Swell - chambers for organs &c. WALKER & SONS, Ltd., J. W., and SYMONDSON, A. H. Nov. 19, 1936, No. 31692. [Classes 13 and 88 (ii)] [Also in Group X] A swell-chamber control for organs, sound-reproducing instruments, apparatus for recording or transmitting sound, &c., comprises hollow louvred shutters open at their meeting edges. The edges of the sheets 2, 3, forming the shutters may overlap, or they may carry overlapping flexible flaps 14, 15. When the hollow spaces in the shutters are large enough, they may facilitate the tuning of organ pipes behind the shutters. The sheets 2, 3, may be formed of wood fibre board and may be spaced apart by an internal zigzag structure 13 of cardboard, or by light wooden blocks. Each shutter is pivoted on upper and lower pins 6 in its top and bottom spacing-blocks, or on a vertical spindle having nuts for tautening the sheets 2, 3. The shutters are opened by a horizontally moved bar 20 formed with a cam 19 which acts through a bell-crank 23 (weighted at 27) and link 25 on a rod 18 which connects lever-blocks 16 on the shutters together. The cam has a gradual initial, and steep final, slope.