Electronic musical instrument capable of generating a string chorus sound

Abstract

Improved apparatus for use in an electronic musical instrument having a keyboard including a group of keys corresponding to the notes of a musical scale. Electronic circuitry is used to generate simultaneously with respect to each of the keys first and second electrical tone signals. The circuitry causes the waveshapes of the tone signals to deviate with respect to each other. In addition, the repetition rates of the tone signals are detuned and frequency modulated with respect to each other so that the sound of a string chorus is simulated. The disclosure also describes circuitry useful in an electronic musical instrument having a keyboard including twelve keys corresponding to the twelve notes of a chromatic musical scale. The circuitry generates simultaneously a first series of twelve tone signals corresponding to a first tempered scale and a second series of twelve tone signals corresponding to a second tempered scale different from the first tempered scale. Each time a key is actuated, a pair of tone signals, one from each of the first and second series, is mixed and converted to an acoustical wave in order to simulate the sound of a string chorus. The disclosure further describes apparatus useful for maintaining the notes of an electronic musical instrument in pitch by phase locking a high frequency oscillator to a low frequency oscillator.