Apparatus for producing musical tones having time variant harmonics
AssigneeKawai Musical Instrument Mfg. Co., Ltd.
InventorRalph Deutsch
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Abstract
An electronic tone generator of a type in which an audio signal of controlled waveform is generated from a stored master data list of digitally coded words incorporates apparatus for changing the harmonic structure of the waveform with time during the generation of the audio signal. The master data list is computed by generating two data lists of words defining different waveforms and multiplying the two lists together repeatedly while shifting one list relative to the other list by at least one word. The resulting master data list changes with each multiplication following a shift, producing a changing waveform in which the musical frequencies are harmonically related, the waveshape being free of intermodulation distortion.
Claims8
A polyphonic tone synthesizer comprising:
- means for storing a master data set of digital values defining a musical waveshape, digital-to-analog converter, means transferring each of said values in sequence, at a sequential rate proprotional to the fundamental pitch of the tone, to said converter, and means for generating such digital values in the master data set including means generating and storing a first set of digitally coded values, means generating and storing a second set of values, means multiplying together and storing the products of pairs of values taken in sequence respectively from said first and second sets of values to form said master data set, and means for shifting the values in the second set relative to the values in the first set to change the pairing of the values from the two sets that are multiplied together.
In an electronic musical instrument, apparatus for producing an audio signal whose waveshape varies with time in a predetermined manner, comprising:
- means for generating a first succession of coded words corresponding to the amplitude of points defining a first periodic waveshape, means for simultaneously generating a second succession of coded words corresponding to the amplitude of points defining a second periodic waveshape, each word of the first succession being generated at the same time as a word in the second succession to form successive pairs of words, multiplying means for multiplying the value of each coded word in said first succession with the paired word in said second succession for providing a succession of resultant words each of which corresponds in coded value to the product of a pair of words from said first and second succession of words, digital-to-analog converter means for converting the succession of resultant words to an analog voltage and means for shifting the time relation between the first and second succession of words to change the pairing of successive words applied to the multiplying means.
Dependencies are inferred from the claim text.