GB1429509A - Electronic musical instrument - Google Patents

Abstract

1429509 Electrophonic musical instruments COMPUTONE Inc 4 July 1973 31894/73 Heading G5J [Also in Division G1] A musical instrument comprises a signal generator giving a fundamental frequency and one or more harmonics and comprising an oscillator 102 with coupling means to an output means 125, and, first and second control means on instrument body 11 to produce continuously variable control signals e w and eg; eg controlling the harmonic content of the signal generator signals and e w controlling independently of frequency the amplitude via main modulator 121. A keying means produces discontinuous output signals e k , which with eg via adder 100 control the frequency of oscillator 102, the effect of eg being weighted. There is a mouthpiece bearing the first control, which is an air flow transducer, and the second control, is a reed-mounted transducer responding to the performer's embouchure varying the reed position. eg and e w may be D.C. voltages. Said coupling means includes adder 104 receiving via variable resistor 107 a manually adjustable reference voltage e t and at least one of eg and e w , and comparator 106 providing the output of the signal generator. A silencing circuit comprises subtractor 126 with a subtracting signal, which varies with changes in e k , provided by absolute value circuit 127. There is a Boehm fingering arrangement, but with extra first and second flat keys and first and second sharp keys with cumulative effects. The waveforms of the signal generator output and of the said oscillator are triangular and the comparator 106 provides a two level output signal, the duration at either level being controlled by its input signals, and this is applied to a lag circuit 108 providing a triangular output waveform, the rise and fall times of which are controlled by the comparative durations of the comparator signal at its two levels. Band pass filters 111 have their centre frequencies in fixed relationship to each other, but controllable by an applied voltage by the performer to track with the frequency variations of the oscillator 102, of which the output is passed to the filters 111 via a time delay circuit 110. The output of filters 111 and e w are applied to modulator 121. Overtone circuit 115, 116, 117, 118 in response to eg and e w produces overtones combined with the output of 111. It comprises a means for supplying eg and e w to function filter elements each of which supplies its output to a multiplier, which is supplied from the corresponding band pass filter. Descriptions and diagrams of the following are given: The air flow and reed transducers (see GIA, GIN), the filter circuit, the overtone circuit and a keying circuit. Fingering charts are also given.