Tone generation and modification apparatus

In apparatus for generating an audio frequency electrical signal adapted for transduction to produce a series of audible tones providing a musical effect:

• time reference means having an output terminal, for generating and presenting at said output terminal thereof a first electrical signal having the character of a series of pulses occurring at a first repetition rate;
• gating means having a switchable electrical path therethrough and a control input terminal electrically coupled with said output terminal of said time reference means, for rendering said switchable path electrically conductive in response to said first electrical signal at intervals corresponding in predetermined manner with said first repetition rate;
• variable electrical level reference means having an output terminal, for generating and presenting at said output terminal thereof a second electrical signal having the character of a series of sawtooth waves occurring at a second repetition rate and each having an instantaneous level varying as a function of time,
• said level reference means including current controlled, sawtooth oscillator means having a control input terminal and configured to oscillate at a frequency determined as a function to the level of an electrical control current applied to said control input terminal thereof,
• said level reference means further including current generator means having an output terminal electrically coupled with said control input terminal of said sawtooth oscillator means for delivering an electrical control current to the latter,
• said current generating means including pattern control means for varying said second repetition rate of said second electrical signal, including current level control structure for varying the level of said control current delivered by said current generator means to said control input terminal of said sawtooth oscillator means;
• memory means having an output terminal and an input terminal electrically coupled with said output terminal of said level reference means through said switchable path of said gating means, for storing the instantaneous level of said second electrical signal whenever said switchable path is electrically conductive and for presenting at said output terminal thereof a third electrical signal having the character of a stepped-level wave in which the successive steps are initiated at intervals corresponding in predetermined manner with said first repetition rate and are of levels corresponding in predetermined manner with the instantaneous level of said second electrical signal that was last previously stored by said memory means;
• and
• tone signal producing means having an output terminal and an input terminal electrically coupled with said output terminal of said memory means, for generating and presenting at said output terminal thereof a fourth electrical signal having the character of a series of tone-representing, audio frequency waveforms occurring in time concurrence with the steps of said third electrical signal and of frequency corresponding in predetermined manner with the concurrent level of said third electrical signal.

In apparatus for generating an audio frequency electrical signal adapted for transduction to produce a series of audible tones providing a musical effect:

• time reference means having an output terminal, for generating and presenting at said output terminal thereof a first electrical signal having the character of a series of pulses occurring at a first repetition rate;
• gating means having a switchable electrical path therethrough and a control input terminal electrically coupled with said output terminal of said time reference means, for rendering said switchable path electrically conductive in response to said first electrical signal at intervals corresponding in predetermined manner with said first repetition rate;
• variable electrical level reference means having an output terminal, for generating and presenting at said output terminal thereof a second electrical signal having the character of a series of sawtooth waves occurring at a second repetition rate and each having an instantaneous level varying as a function of time;
• memory means having an output terminal and an input terminal electrically coupled with said output terminal of said level reference means through said switchable path of said gating means, for storing the instantaneous level of said second electrical signal whenever said switchable path is electrically conductive and for presenting at said output terminal thereof a third electrical signal having the character of a stepped-level wave in which the successive steps are initiated at intervals corresponding in predetermined manner with said first repetition rate and are of levels corresponding in predetermined manner with the instantaneous level of said second electrical signal that was last previously stored by said memory means;
• tone signal producing means having an output terminal and an input terminal electrically coupled with said output terminal of said memory means, for generating and presenting at said output terminal thereof a fourth electrical signal having the character of a series of tone-representing, audio frequency waveforms occurring in time concurrence with the steps of said third electrical signal and of frequency corresponding in predetermined manner with the concurrent level of said third electrical signal;
• and
• means for providing and applying a modulation signal to said input terminal of said tone signal producing means,
• whereby said third electrical signal is mixed with and modified by said modulation signal to thereby alter the characteristics of said fourth electrical signal.

In apparatus for generating an audio frequency electrical signal adapted for transduction to produce a series of audible tones providing a musical effect:

• time reference means having an output terminal, for generating and presenting at said output terminal thereof a first electrical signal having the character of a series of pulses occurring at a first repetition rate;
• gating means having a switchable electrical path therethrough and a control input terminal electrically coupled with said output terminal of said time reference means, for rendering said switchable path electrically conductive in response to said first electrical signal at intervals corresponding in predetermined manner with said first repetition rate;
• variable electrical level reference means having an output terminal, for generating and presenting at said output terminal thereof a second electrical signal having the character of a series of sawtooth waves occurring at a second repetition rate and each having an instantaneous level varying as a function of time;
• memory means having an output terminal and an input terminal electrically coupled with said output terminal of said level reference means through said switchable path of said gating means, for storing the instantaneous level of said second electrical signal whenever said switchable path is electrically conductive and for presenting at said output terminal thereof a third electrical signal having the character of a stepped-level wave in which the successive steps are initiated at intervals corresponding in predetermined manner with said first repetition rate and are of levels corresponding in predetermined manner with the instantaneous level of said second electrical signal that was last previously stored by said memory means;
• tone signal producing means having an output terminal and an input terminal electrically coupled with said output terminal of said memory means, for generating and presenting at said output terminal thereof a fourth electrical signal having the character of a series of tone-representing, audio frequency waveforms occurring in time concurrence with the steps of said third electrical signal and of frequency corresponding in predetermined manner with the concurrent level of said third electrical signal;
• a resistance electrically coupled in series between said output terminal of said memory means and said input terminal of said tone signal producing means;
• capacitance means having a pair of terminals of which one is electrically grounded;
• and
• means for selectively electrically coupling the other terminal of said capacitance means with said input terminal of said tone signal producing means,
• whereby to provide a portamento effect in the characteristics of said waveforms of said fourth electrical signal.

In apparatus for generating an audio frequency electrical signal adapted for transduction to produce a series of audible tones providing a musical effect:

• time reference means having an output terminal, for generating and presenting at said output terminal thereof a first electrical signal having the character of a series of pulses occurring at a first repetition rate;
• gating means having a switchable electrical path therethrough and a control input terminal electrically coupled with said output terminal of said time reference means, for rendering said switchable path electrically conductive in response to said first electrical signal at intervals corresponding in predetermined manner with said first repetition rate;
• variable electrical level reference means having an output terminal, for generating and presenting at said output terminal thereof a second electrical signal having the character of a series of sawtooth waves occurring at a second repetition rate and each having an instantaneous level varying as a function of time;
• memory means having an output terminal and an input terminal electrically coupled with said output terminal of said level reference means through said switchable path of said gating means, for storing the instantaneous level of said second electrical signal whenever said switchable path is electrically conductive and for presenting at said output terminal thereof a third electrical signal having the character of a stepped-level wave in which the successive steps are initiated at intervals corresponding in predetermined manner with said first repetition rate and are of levels corresponding in predetermined manner with the instantaneous level of said second electrical signal that was last previously stored by said memory means,
• said memory means including a capacitance having a pair of terminals of which one is electrically coupled with said input terminal of said memory means and the other is electrically grounded,
• said memory means further including a signal follower unit electrically coupled in series between said input terminal and said output terminal of said memory means;
• tone signal producing means having an output terminal and an input terminal electrically coupled with said output terminal of said memory means, for generating and presenting at said output terminal thereof a fourth electrical signal having the character of a series of tone-representing, audio frequency waveforms occurring in time concurrence with the steps of said third electrical signal and of frequency corresponding in predetermined manner with the concurrent level of said third electrical signal;
• and
• means for selectively electrically coupling one terminal of electrical resistance means having the other terminal thereof electrically grounded with said input terminal of said memory means in parallel with said capacitance,
• whereby to provide an immediate rising pitch drift effect in the characteristics of said waveforms of said fourth electrical signal.

In apparatus for generating an audio frequency electrical signal adapted for transduction to produce a series of audible tones providing a musical effect:

• time reference means having an output terminal, for generating and presenting at said output terminal thereof a first electrical signal having the character of a series of pulses occurring at a first repetition rate;
• gating means having a switchable electrical path therethrough and a control input terminal electrically coupled with said output terminal of said time reference means, for rendering said switchable path electrically conductive in response to said first electrical signal at intervals corresponding in predetermined manner with said first repetition rate;
• variable electrical level reference means having an output terminal, for generating and presenting at said output terminal thereof a second electrical signal having the character of a series of sawtooth waves occurring at a second repetition rate and each having an instantaneous level varying as a function of time;
• memory means having an output terminal and an input terminal electrically coupled with said output terminal of said level reference means through said switchable path of said gating means, for storing the instantaneous level of said second electrical signal whenever said switchable path is electrically conductive and for presenting at said output terminal thereof a third electrical signal having the character of a stepped-level wave in which the successive steps are initiated at intervals corresponding in predetermined manner with said first repetition rate and are of levels corresponding in predetermined manner with the instantaneous level of said second electrical signal that was last previously stored by said memory means;
• and
• tone signal producing means having an output terminal and an input terminal electrically coupled with said output terminal of said memory means, for generating and presenting at said output terminal thereof a fourth electrical signal having the character of a series of tone-representing, audio frequency waveforms occurring in time concurrence with the steps of said third electrical signal and of frequency corresponding in predetermined manner with the concurrent level of said third electrical signal,
• said tone signal producing means including current controlled relaxation oscillator means having a common input and output terminal and capacitance means having a terminal thereof electrically coupled with said common terminal, the other terminal of said capacitance means being electrically grounded, said relaxation oscillator being configured to oscillate at a frequency determined as a function of the level of an electrical control current applied to said common terminal thereof, said tone signal producing means further including voltage controlled, current producing means having an input terminal constituting said input terminal of said tone signal producing means and an output terminal electrically coupled with said common terminal of said relaxation oscillator means, said current producing means being configured for delivering to said relaxation oscillator a control current of level varying in response to variation of the potential level of said third electrical signal applied to said input terminal of said current producing means.

In apparatus for generating an audio frequency electrical signal adapted for transduction to produce a series of audible tones providing a musical effect:

• time reference means having an output terminal, for generating and presenting at said output terminal thereof a first electrical signal having the character of a series of pulses occurring at a first repetition rate;
• gating means having a switchable electrical path therethrough and a control input terminal electrically coupled with said output terminal of said time reference means, for rendering said switchable path electrically conductive in response to said first electrical signal at intervals corresponding in predetermined manner with said first repetition rate;
• variable electrical level reference means having an output terminal, for generating and presenting at said output terminal thereof a second electrical signal having the character of a series of sawtooth waves occurring at a second repetition rate and each having an instantaneous level varying as a function of time;
• memory means having an output terminal and an input terminal electrically coupled with said output terminal of said level reference means through said switchable path of said gating means, for storing the instantaneous level of said second electrical signal whenever said switchable path is electrically conductive and for presenting at said output terminal thereof a third electrical signal having the character of a stepped-level wave in which the successive steps are initiated at intervals corresponding in predetermined manner with said first repetition rate and are of levels corresponding in predetermined manner with the instantaneous level of said second electrical signal that was last previously stored by said memory means;
• tone signal producing means having an output terminal and an input terminal electrically coupled with said output terminal of said memory means, for generating and presenting at said output terminal thereof a fourth electrical signal having the character of a series of tone-representing, audio frequency waveforms occurring in time concurrence with the steps of said third electrical signal and of frequency corresponding in predetermined manner with the concurrent level of said third electrical signal;
• a resistance having one end thereof electrically coupled with ground;
• a clamping diode electrically coupled in shunt with said resistance;
• a capacitance electrically coupled in series between said output terminal of said tone signal producing means and the other end of said resistance;
• an output lead having a second diode in series therewith electrically coupled with said other end of said resistance;
• means providing a gating signal having the character of a series of pulses occurring at said first repetition rate;
• an electronic gate having a switchable path therethrough and a control input terminal selectively electrically connectable with said gate signal providing means, for rendering said switchable path through said gate electrically conductive in response to said gating signal at intervals corresponding in predetermined manner with said first repetition rate;
• and
• electrical circuit means for electrically coupling said switchable path of said gate in shunt with said capacitance,
• whereby said waveforms of said fourth electrical signal are modified to provide a decaying volume or percussion-like effect.

In apparatus for generating an audio frequency electrical signal adapted for transduction to produce a series of audible tones providing a musical effect:

• time reference means having an output terminal, for generating and presenting at said output terminal thereof a first electrical signal having the character of a series of pulses occurring at a first repetition rate;
• gating means having a switchable electrical path therethrough and a control input terminal electrically coupled with said output terminal of said time reference means, for rendering said switchable path electrically conductive in response to said first electrical signal at intervals corresponding in predetermined manner with said first repetition rate;
• variable electrical level reference means having an output terminal, for generating and presenting at said output terminal thereof a second electrical signal having the character of a series of sawtooth waves occurring at a second repetition rate and each having an instantaneous level varying as a function of time;
• memory means having an output terminal and an input terminal electrically coupled with said output terminal of said level reference means through said switchable path of said gating means, for storing the instantaneous level of said second electrical signal whenever said switchable path is electrically conductive and for presenting at said output terminal thereof a third electrical signal having the character of a stepped-level wave in which the successive steps are initiated at intervals corresponding in predetermined manner with said first repetition rate and are of levels corresponding in predetermined manner with the instantaneous level of said second electrical signal that was last previously stored by said memory means;
• tone signal producing means having an output terminal and an input terminal electrically coupled with said output terminal of said memory means, for generating and presenting at said output terminal thereof a fourth electrical signal having the character of a series of tone-representing, audio frequency waveforms occurring in time concurrence with the steps of said third electrical signal and of frequency corresponding in predetermined manner with the concurrent level of said third electrical signal;
• and
• filter means electrically coupled with said output terminal of said tone signal producing means for selectively applying frequency filtering to said fourth electrical signal to modify the frequency characteristics of said waveforms of the latter in controlled manner, said filter means including
• a filter ladder having a pair of side portions and a plurality of cross-bar portions,
• each of said side portions comprising a plurality of diodes electrically coupled in series,
• each of said cross-bar portions comprising a fixed value capacitance;
• input means electrically coupled with said output terminal of said tone signal producing means for applying an alternating current signal corresponding to said fourth electrical signal to one side portion of said ladder at one end of the latter;
• output means electrically coupled with said one side portion of said ladder adjacent the opposite end thereof for deriving an electrical output signal therefrom;
• inverting feedback means electrically coupled between said output means and the other side portion of the ladder at said one end of the latter for applying thereto an alternating current signal corresponding to an inverted version of said output signal;
• and
• means electrically coupled with said ladder for causing a controllably variable flow of direct current through said diodes,
• whereby said ladder functions as a low pass filter having a controllably variable cut-off frequency.

In a ladder type adjustable cut-off, low pass, electronic filter:

• a first plurality of diodes electrically coupled in series to present one side portion of a filter ladder;
• a second plurality of diodes electrically coupled in series to present the other side portion of said filter ladder;
• a plurality of fixed value capacitances respectively electrically coupled across said ladder between points of interconnection of corresponding adjacent pairs of said diodes in said side portions of said ladder to present the cross-bars of said filter ladder;
• means for applying an alternating current signal to be filtered to said one side portion of said filter ladder at one end of the latter;
• means for applying an electrically inverted version of said alternating current signal to said other side portion of said filter ladder at said one end of the latter;
• means for causing a flow of direct current through both of said side portions of said filter ladder;
• means for varying the level of said direct current flow;
• and
• means for deriving a filtered output from said filter ladder adjacent the opposite end thereof.

In apparatus for generating an audio frequency electrical signal adapted for transduction to produce a series of audible tones providing a musical effect:

• first voltage controlled current generator means having a pair of selectively activatable control input terminals, and an output terminal;
• means for providing a first control voltage of adjustable level having an output terminal electrically coupled with one of said control input terminals of said first current generator means;
• first current controlled oscillator means having a control input terminal electrically coupled with said output terminal of said first current generator means, and an output terminal;
• one-shot multivibrator means having a trigger input terminal electrically coupled with said output terminal of said first oscillator means, and an output terminal;
• second voltage controlled current generator means having a pair of selectively activatable control input terminals, and an output terminal;
• means for providing a second control voltage of adjustable level having an output terminal electrically coupled with one of said control input terminals of said second current generator means;
• second current controlled oscillator means having a control input terminal electrically coupled with said output terminal of said second current generator means, and an output terminal;
• electrical level memory means having a signal input terminal, and a signal output terminal;
• gate means having a gating input terminal electrically coupled with said output terminal of said multivibrator means, and a pair of switched path terminals of which one is electrically coupled with said output terminal of said second oscillator means and the other is electrically coupled with said signal input terminal of said level memory means;
• third voltage controlled current generator means having a control signal input terminal electrically coupled with said output terminal of said level memory means, and an output terminal;
• and
• third current controlled oscillator means having a control input terminal electrically coupled with said output terminal of said third current generator means, and output means for delivering a tone signal output.