| 摘要 |
A device for electronically modulating a musical tone signal to produce substantially the radiation effects produced by a rotary loudspeaker with the aid of two loudspeakers, in which circuit an amplitude modulator is associated with one loudspeaker and a variable delay device is associated with the other loudspeaker, the musical tone signal being applied to both the amplitude modulator and the variable delay device, and both the variable delay device and the amplitude modulator being modulated synchronously by a sub-audio frequency modulating signal. The amplitude modulator delivers an output to its loudspeaker only during positive half cycles of the modulating signal, during which time the frequency modulated signal produced by the variable delay device is going from sharp to flat, and during the period that no amplitude modulated tone signal is produced the frequency modulated signal is going from flat to sharp, whereby when the separately reproduced modulated signals are acoustically mixed a rotating sound effect is produced.
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