GB291050A - Improvements in musical instruments provided with a pitch indicator - Google Patents

Abstract

291,050. Mirfield, T. N. May 25, 1927, [Convention date]. Acoustic and vibration frequency speed indicators.-To facilitate tuning, the pitch of a drum, double-bass, 'cello, &c., is indicated by communicating forced vibrations from the instrument to a set of tuned reeds, that reed vibrating with the greatest amplitude which corresponds to the note of the instrument. The vibrations may be communicated mechanically, electromagnetically, or by a diaphragm receiving the air-vibrations. The vibration of the reeds may be shown by reflected beams of light. In the drum 12, the tuned metallic reeds 24 are mounted in open cells on a bar 22 rocking on springs 21, the bar 22 also carrying an arm 26 with pad 27 which transmits the vibrations of the drum-head 13. The reeds carry mirrors and reflect beams of light from a lamp 32, to adjustable mirrors 34 and thence to the translucent head 13 on which a scale is painted. The device is put out of action by a crank-handle 61, which controls the lamp, and also, by a cam 51 and arm 53, permits a spring 46 to lower an arm 42 pivoted at 40, a spring 56 being then permitted to raise an arm 55 pivoted at 41. The arms 42, 55 carry dampers 44, 59 which thus nip the reeds, and the arm 42 also depresses the arm 26 out of contact with the drum-head. In a modification the arm 26 contacts with the upper surface of the drum-heads and the reeds are observed directly. The reeds may be tuned to harmonics or other compounds, instead of to fundamental notes.