GB1399179A - Electronic musical instrument capable of providing a third type of musical tones by operation of two keyboards in addition to the ordinary melody and chord tones - Google Patents

Abstract

1399179 Electrophonic musical instrument NIPPON GAKKI SEIZO KK 30 May 1973 [30 May 1972 (4)] 25765/73 Heading G5J With upper (melody) keyboard 13 and lower (chord) keyboard 15 conventionally connecting appropriate tone generators 11 via keyers 12, 14 through channels 1 and II to output amplifier 17 and loudspeaker 18, a third channel III to output is provided by gating at 20 signals from those tone generators already selected by chord keyboard 15 so that such tones, synchronized with melody keyboard 13 by being given percussive envelope form when any melody key is pressed, or sustained as long as such a key is pressed, are fed additionally to output. In each channel tone colouring filters 16, 19, 22 modify the tones. Gate 20 is controlled via detector 21 operated either directly by any keyswitch in keyer 12, or by detecting the presence of any melody tone signal switched on by keyer 12. When operated by keyswitches, a monostable multivibrator in detector 21 is triggered by any keyswitch, resetting itself after a fixed time. To produce a percussive envelope, multivibrator step output is converted to exponential decay by adjustable R-C differentiating circuit, with diode elimination of reverse pulses at reset. When operated by the presence of a signal, the melody tone is amplified, rectified, smoothed and finally passed to an adjustable R-C differentiating circuit if percussive envelope is required. In all cases the detector output controls a FET as gate 20. In an alternative embodiment (Fig. 6, not shown), gate 20 is duplicated, feeding separate tone colouring filters with percussive and sustained envelopes; their outputs, combined via volume controls and stop switches, are fed to the amplifier 7 and loud-speaker 18 optionally via a modulator driven by low frequency oscillator providing amplitude, frequency or tone colour vibrate or tremolo modulation. In a third embodiment (Fig. 9, not shown), the melody keyboard is divided into octave ranges, controlling separate detectors and gates, each feeding a separate tone colour filter. The notes passed by each gate, either percussive or sustained, agree in position in an octave with those played on the chord keyboard, but their footage (octave) rises in step with the octave of melody keys controlling that gate.