| 摘要 |
1522850 Electrophonic musical instruments ROLAND CORP 17 Nov 1975 [7 Dec 1974] 47265/75 Heading G5J A device for modulating a musical tone to produce a rotating sound effect comprises three amplitude modulators 4A, 4B, 4C, one of which 4B receives the musical tone direct while the other two receive it through a delay circuit 3, a modulation signal generator 2 providing control signals to the delay circuit and the modulator 4B direct, and to the modulators 4A and 4C via phase shifters P1 and P2, and there being an audio coupling, Fig. 2, or a combination of electronic and audio coupling (Fig. 6, not shown) so that when the volume of the tone from amplifier 5A is a maximum, its frequency is also a maximum, when the volume of the tone from amplifier 5C is a maximum its frequency is a minimum, and on successive occasions when the volume from amplifiers 5A and 5C are equal, the volume from amplifier 5B is alternately a maximum or a minimum. When a combination of electronic and audio coupling is employed (Fig. 6), the output from modulator 4B is supplied half to each of amplifiers 5A and 5C, amplifier 5B and loudspeaker 7 being omitted. The phase of the modulation envelope of the outputs from each of the modulators 4A and 4C is usually displaced by 90 degrees from that of 4B, although by including summing circuits between the pairs of signals F 0 , F 1 and F 0 , F 2 a variable phase change of 0 to 90 degrees may be derived.
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