GB1537151A - Pulsato generating system - Google Patents

Abstract

1537151 Electronic musical instruments ROLAND CORP 15 Jan 1976 [18 Jan 1975 (3) 20 Jan 1975 (2)] 01567/76 Heading G5J The invention concerns a system 2 for producing a pulsato effect electronically. The incoming tone signal A is applied to a phase shifter 3 producing quadrature signals E1, E2. A low modulating frequency F is applied to a divide-by-two circuit 8 to provide four quadrative square wave gating signals G1, G2, G3, G4. Antiphase pairs of the gating signals are used, in a gating circuit 6, to gate respectively the two signals E1, E2 to a modulating amplifier assembly 10. A modulation generator 12 provides two antiphase sine waves I1, I2 at the frequency F. The signals H1, H3, which are intermittent signals produced alternately by gates 5a, 5b from signals E1, are added in antiphase, by applying them respectively to the true and inverting inputs of a modulating amplifier 11a, and modulated by signal I<SP>1</SP> to provide the signal J1 which has portions alternately in antiphase as shown in Fig. 2 (where the triangular waveforms and envelopes represent actual sine waves). A second signal J2 is derived similarly or more simply by inverting the output of amplifier 11a (Fig. 3, not shown) while a third signal J3 is similarly derived from H2, H4 and modulating signal I2. The three signals J1, J2, J3 may be applied to individual loudspeakers to provide the desired effect (Fig. 5, not shown) or may be combined to provide signals K1, K2 to only two loudspeakers 18a, 18b. A further loudspeaker (18c, Fig. 4, not shown) may receive the tone signal A direct. Also described (Figs. 6-15, not shown) are various "chorus" effect generators for insertion between tone generator 1 and the system 2 and which comprise means for modulating a portion or portions of the input signal at low frequency and then adding them to other portions of the input signal.