Patent GB-455324-A (GB)
Title: Improvements in or relating to electric musical instruments
IPC: G10H5/08
Filed: 1935-09-21
Abstract: 455,324. Electrical musical instruments. STANDARD TELEPHONES & CABLES, Ltd., 63, Aldwych, London.- (Assignees of Le MatÚriel Telephonique Soc. Anon.; 46, Quai de Boulogne, Boulogne-sur- Seine, France) Sept. 21, 1935, No. 26206. Convention date, Sept. 21, 1934. [Class 88 (ii)] The oscillations of a separate valve 1, 2, &c. for each musical note, are caused to beat with those of a common master oscillating-valve M, the product being passed through a number of detector-valves A, B, C, tuned respectively to the fundamental frequency and first and second harmonics of the master oscillator, timbre-stops being provided to determine the proportions between the detector-outputs (each corresponding to an order of partials) fed to a loud-speaker LS through an amplifier BF. The oscillators 1, 2 &c. are controlled by note-keys I1, I2 &c. arranged in a manual, several of which manuals may be provided, each having pitch-stop keys and switching means for coupling with other manuals. The valveoscillations are stabilized and made rich in harmonics by quartz crystals Q0, Q1 &c., or by metal subject to magnetostriction. The masteroscillator and note-oscillators feed the detectors A, B, C through inductances L1, L2, L3 and Kl, K2, K3 respectively, the proportionate outputs of the detectors being controlled either by timbre-switches for shunting resistances R1, R2, R3 across the series-connected secondaries S1, S2, S3 of output transformers leading to the amplifier, or by switches governing tappings of the secondaries themselves or of potentiometers shunting them. In a two-manual arrangement shown in Fig. 3, each note-key (one only shown) of the manuals cl1 and cl2 simultaneously closes four contacts 1 ... 4 and 9 ... 12 respectively, the four contacts of each key leading respectively to oscillators OSC1 . . . 4, which produce with the master oscillator notes bearing the same name but successively an octave apart, the one or more octaves which is or are sounded when a note-key is depressed being governed by pitch-stop keys 5 ... 8 and 13 ... 16 associated with each manual. Each manual controls its own set of detectors provided with timbre-control and loud-speaker, the sets being fed respectively from sources of high-tension current + 80 No. 1 and + 80 No. 2, through inductances a and b each of which corresponds to a series of inductances such as Kl, K2, K3, Fig. 1. Coupling switches X, Y act as follows. In the position shown, manual cl1 is independently effective, cl2 being inoperative. Closing the switch Y in its upper position renders also the manual cl2 independently effective. With switch Y in this position, closing the switch X couples the two manuals reciprocally so that playing a note on either manual sounds notes simultaneously in the loud-speakers of each, the octave-pitch of both being the same, as determined by the pitchstop key 5 ... 16 of the manual operated, but the timbres may differ, as determined by the timbre-stops associated with each manual. With the switch Y closed in its lower position and X open, the manual cl2 is fed from an additional high-tension source + 80 No. 3 through further inductances a<1>, b<1> associated respectively with the detectors of manuals cl1 and cl2. The manual cl1 is thus in effect coupled to the manual cl2 to sound when cl2 is played, but cl1 may be played independently. A schematic arrangement of three manuals is also shown. The instrument may bo played automatically.