Electronic musical instrument using amplitude modulation with feedback loop

An electronic musical instrument comprising:

• keyboard means having a plurality of keys;
• carrier wave generating means for generating a carrier wave corresponding to a depressed one of said keys;
• modifying means for modifying said carrier wave in accordance with a modifying signal and for delivering a modified carrier wave;
• modulation signal generating means for generating a modulation signal;
• amplitude modulation means for amplitude-modulating said modified carrier wave by multiplying said modified carrier wave with said modulation signal, the resultant amplitude-modulated modified carrier wave being utilized to generate a musical tone signal;
• and
• feedback means for generating said modifying signal by delaying said amplitude-modulated modified carrier wave and providing said delayed amplitude-modulated modified carrier wave as said modifying signal.

An electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave having a certain frequency;
• amplitude modulation means for amplitude-modulating said carrier wave by multiplying said carrier wave with a modulation signal, the resultant signal being delivered as an amplitude-modulated carrier wave to be used for producing a musical tone signal;
• and
• feedback means for generating said modulation signal by delaying said amplitude-modulated carrier wave and providing said delayed amplitude-modulated carrier wave as said modulation signal, and wherein said feedback means comprises:
• modulation index generating means for generating a modulation index;
• and
• a multiplier for multiplying said amplitude-modulated carrier wave by said modulation index, said multiplied amplitude-modulated carrier wave being delayed and provided as said modulation signal.

An electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave having a certain frequency;
• amplitude modulation means for amplitude-modulating said carrier wave by multiplying said carrier wave with a modulation signal, the resultant signal being delivered as an amplitude-modulated carrier wave to be used for producing a musical tone signal;
• and
• feedback means for generating said modulation signal by delaying said amplitude-modulated carrier wave and providing said delayed amplitude-modulated carrier wave as said modulation signal, and wherein said feedback means comprises:
• a modulation index generator for generating a modulation index;
• a multiplier for multiplying said amplitude-modulated carrier wave with said modulation index, and
• modulation signal memory means for storing said modulation signal and for generating said modulation signal in accordance with a product output of said multiplier.

An electronic musical instrument comprising:

• keyboard means having a plurality of keys;
• carrier wave generating means for generating a carrier wave having a frequency corresponding to a depressed one of said keys;
• amplitude modulation means for amplitude-modulating said carrier wave in accordance with a modulation signal and for delivering an amplitude-modulated carrier wave to be used for producing a musical tone signal;
• feedback means for generating said modulation signal in accordance with said amplitude-modulated carrier wave, and wherein said feedback means comprises:
• a first to Nth modulation signal generating means (where N is an integer larger than 1) for generating first to Nth modulation signals respectively, said first modulation signal being generated in accordance with said amplitude-modulated carrier wave;
• a first to N-1th additional carrier wave generating means for generating first to N-1th carrier waves respectively;
• a first to N-1th additional amplitude modulation means, which are connected to the first to N-1th additional carrier wave generating means respectively and to the first to N-1th modulation signal generating means respectively, for amplitude modulating the first to N-1th carrier waves respectively in accordance with respective first to N-1th modulation signals and for delivering first to N-1th amplitude modulated carrier waves respectively, the first to N-1th amplitude modulated carrier waves being applied to the second to Nth modulation signal generating means respectively and the Nth modulation signal being said modulation signal.

An electronic musical instrument comprising:

• keyboard means having a plurality of keys;
• carrier wave generating means for generating a carrier wave corresponding to a depressed one of said keys;
• modifying means for modifying said carrier wave in accordance with a modifying signal and for delivering a modified carrier wave;
• modulation signal generating means for generating a modulation signal;
• amplitude modulation means for amplitude-modulating said modified carrier wave in accordance with said modulation signal and for delivering an amplitude-modulated modified carrier wave utilized to generate a musical tone signal;
• feedback means for generating said modifying signal in accordance with said amplitude-modulated modified carrier wave, and wherein said feedback means comprises:
• a first to Nth modulation signal generating means (where N is an integer larger than 1) for generating first to Nth modulating signals respectively, said first modulation signal being generated in accordance with said amplitude-modulated modified carrier wave;
• a first to N-1th additional carrier wave generating means for generating first to N-1th carrier waves respectively;
• and
• a first to N-1th additional amplitude modulating means, which are connected to the first to N-1th additional carrier wave generating means respectively and to the first to N-1th modulation signal generating means respectively, for amplitude-modulating the first to N-1th carrier waves respectively in accordance with the respective first to N-1th modulation signals and for delivering first to N-1th amplitude-modulated modified carrier waves respectively, the first to N-1th amplitude-modulated modified carrier waves being applied to the second to Nth modulation signal generating means respectively and the Nth modulation signal being said modifying signal.

An electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave having a certain frequency;
• amplitude modulation means for amplitude-modulating said carrier wave by multiplying said carrier wave with a modulation signal, the resultant signal being delivered as an amplitude-modulated carrier wave to be used for producing a musical tone signal;
• and
• feedback means for generating said modulation signal by delaying said amplitude-modulated carrier wave and providing said delayed amplitude-modulated carrier wave as said modulation signal, and wherein;
• said carrier wave is a digitalized carrier wave, and said amplitude modulation means and said feedback means are digitalized, and which further comprises;
• an averaging circuit for eliminating undesirable hunting phenomena.

An electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave having a frequency corresponding to a selected note;
• amplitude modulation means for multiplying said carrier wave by a modulation signal and for delivering the resultant signal as an amplitude-modulated carrier wave to be used for producing a musical tone signal;
• and
• feedback means for generating said modulation signal by multiplying said amplitude-modulated carrier wave by a selected modulation index, the resultant product being delayed and provided as said modulation signal.

An electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave corresponding to a selected note;
• modifying means for modifying said carrier wave in accordance with a modifying signal and for delivering a modified carrier wave;
• modulation signal generating means for generating a modulation signal;
• amplitude modulation means for multiplying said modified carrier wave with said modulation signal and for delivering the resultant signal as an amplitude-modulated modified carrier wave utilized to generate a musical tone signal;
• and
• feedback means for generating said modifying signal by multiplying said amplitude-modulated modified carrier wave by a selected modulation index, the resultant product being delayed and provided as said modifying signal.

A digital electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave having a frequency corresponding to a selected musical note, said carrier wave being represented by successive sample point amplitude values provided at regular time intervals;
• amplitude modulation means for amplitude-modulating said carrier wave by multiplying the sample point amplitude values of said carrier wave with a time sampled modulation signal, the resultant signals being delivered as sample point amplitude data of an amplitude-modulated carrier wave to be used for producing a musical tone signal;
• and
• feedback means for generating said modulation signal by delaying the sample point amplitude data of said amplitude-modulated carrier wave and providing said delayed amplitude-modulated carrier wave sample point amplitude data as said time sampled modulation signal;
• whereby the tone color of a musical tone corresponding to said musical tone signal will vary according to the lapse of time.

An electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave having a frequency corresponding to a selected musical note and having a relatively simple waveform;
• amplitude modulation means for multiplying the successive amplitudes of said carrier wave with successive values of a modulation signal, the resultant successive signals being delivered as an amplitude-modulated carrier wave to be used for producing a musical tone signal;
• and
• feedback means for generating said modulation signal by delaying said amplitude-modulated carrier wave signals and providing said delayed amplitude-modulated carrier wave signals as said successive modulation signal values, whereby an amplitude-modulated carrier wave having a time varying complex waveform, suitable to production of a corresponding musical tone having a time varying tone color, is created out of a carrier wave of simple waveform.

An electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave having a frequency corresponding to a selected musical note;
• amplitude modulation means for multiplying the amplitudes of said carrier wave at regular time intervals within each cycle of said carrier wave with a modulation signal, the resultant signal being delivered as an amplitude-modulated carrier wave to be used as a musical tone signal;
• and
• feedback means for generating said modulation signal by modifying said amplitude-modulated carrier wave and providing said modifying amplitude-modulated carrier wave signals as said modulation signal, said modifying being one or both of delaying and multiplying by a selected modulation index value;
• whereby said musical tone signal will exhibit a time varying waveshape and hence a musical tone corresponding to said musical tone signal will exhibit a time varying tone color.

In a digital electronic musical instrument, a system for producing a relatively complex musical tone waveform from a carrier wave of relatively simple waveform which is supplied as an input to said system, comprising:

• means for multiplying successive amplitude samples of said carrier wave with successive values of a modulation signal, the resultant signals being used as a musical tone signal;
• and
• feedback means for delaying said resultant signals and providing said delayed resultant signals as said modulation signal successive values,
• said multiplying means and said feedback means being operative in real time and producing by said multiplying a musical tone signal having a waveform which varies with the lapse of time, so that the tone color of a musical tone corresponding to said musical tone signal likewise will vary with the lapse of time.

An electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave having a certain frequency;
• amplitude modulation means for amplitude-modulating said carrier wave by multiplying said carrier wave with a modulation signal, the resultant signal being delivered as an amplitude-modulated carrier wave to be used as a musical tone signal;
• modifying means for modifying said amplitude-modulated carrier wave, said modifying being one or both of delaying and multiplying by a selected modulation index value;
• and
• modulation signal providing means for providing said modified amplitude-modulated carrier wave as said modulation signal, whereby the waveform of said delivered amplitude-modulated carrier wave, and hence the tone color of a musical tone corresponding thereto, will vary in accordance with the lapse of time.

An electronic musical instrument comprising:

• carrier wave generating means for generating a carrier wave having a certain frequency;
• amplitude modulation means for amplitude-modulating said carrier wave by multiplying said carrier wave with a modulation signal, the resultant signal being delivered as an amplitude-modulated carrier wave to be used as a musical tone signal;
• feedback means for generating said modulation signal by delaying said amplitude-modulated carrier wave and providing said delayed amplitude-modulated carrier wave as said modulation signal;
• said delaying and said multiplying causing said musical tone signal to have a waveshape which varies with lapse of time, so that the tone color of a musical tone corresponding to said musical tone signal likewise will vary with lapse of time.