Abstract: In an electronic musical instrument of the waveshape memory type including at least one waveshape memory for storing and reproducing sample values of a musical sound wave to be generated, the waveshape memory stores the sample values of the complete waveshape of a musical tone with a shaped envelope.

Abstract: An envelope generator for use in an electronic musical instrument, such as an electronic organ, employing a dual charge pump to form the attack and decay portions of the envelope. The envelope generator is adapted to be connected to the envelope control input of the keyer and the other input of the keyer is connected to a tone source. When the appropriate key of the keyboard is depressed, a source of input voltage is connected to the input of the envelope generator and a first charge pump incrementally transfers the input voltage to a capacitor over a first sequence of discrete time frames. The first charge pump circuit comprises a pair of electronic switches clocked 180.degree. out of phase and a capacitor connected between the juncture of the two switches and ground potential. The second mentioned capacitor is much larger than the first mentioned capacitor so that the charge transfer from one to the other takes place in a plurality of discrete steps.

Abstract: A method and apparatus for interpolating between the harmonic structures of a waveform stored in memory during the transient periods of said waveform. In an electronic musical instrument having a greater number of selectively actuable switches than generators to cause the production of sound corresponding to the respective notes of the musical scale the present invention interpolates between the harmonic structures of a waveform stored in memory during the transient period of that waveform. This is accomplished through the use of memory units having a number of locations or zones within each memory where the number of zones is equivalent to the number of discrete harmonic structures. The first of the memory units contains a discrete fixed harmonic structure in each of its zones, and a second of the memory units contains a difference value in each of its zones where the difference value is equal to the difference between the discrete fixed harmonic structure in adjacent zones of the first memory.

Abstract: A digital envelope generator implemented in the form of an off-the-shelve microcomputer is disclosed. Five envelopes are produced simultaneously in multiplexed form and are output via a digital-to-analog converter and multiplexer to corresponding voltage controlled amplifiers/filters. The outputs are scaled in amplitude in accordance with touch response signals derived from a keyboard and the envelope time constants are scaled in accordance with the pitch of the notes selected by the keyboard. The outputs are available without further modification for controlling the Q of the filters, or the gain of amplifiers, and are simultaneously available with the amplitude scaled in accordance with the pitch of selected notes for controlling the frequency response of the voltage controlled filters.

Abstract: A keyboard operated musical instrument is disclosed having a portamento effect controlled from a portamento keyboard consisting of a linear array of keyswitches. The keyswitches are arranged in groups corresponding to each musical note and spaced so that a number of contiguous switches are actuated by each finger in contact with the portamento keyboard. Apparatus is provided for generating a frequency number corresponding to the closest switch actuated by the center of each finger thereby providing polyphonic portamento effects as the finger positions are slid along the portamento keyboard. An ADSR generator is used to provide envelope modulations initiated when a new finger has been detected on the slide wire and when a finger has been removed. A priority logic using frequency differences is used to distinguish between new fingers or the changes in position of a finger already in contact with the slide wire.

Abstract: In a keyboard operated electronic musical instrument a detector is provided for measuring the time interval between successively actuated keyswitches. If the time interval is less than a preselected time threshold, the notes are generated with a normal ADSR envelope and if the time interval exceeds this time threshold then the notes are generated with a legato ADSR envelope. Provision is provided to accomodate variations in time when a chord is played. The system will return to the normal ADSR for time intervals greater than that for a second preselected time threshold for notes played with large time separations. The same control signals are provided to control other musical effects such as tone selection, vibrato and portamento.

Abstract: An MOS integrated organ circuit compensates an audio frequency signal for variations in amplitude, attack and decay characteristics caused by process variations by adjusting a single variable reference voltage. The circuit intrinsically provides for the tracking of these characteristics, such that the attack and decay characteristics are calibrated by adjusting the variable reference voltage to provide a specified amplitude characteristic.

Abstract: An improved envelope generator circuit for an electronic organ provides a musically correct attack rate, i.e., the volume of a musical note is increased by an equal number of decibels for equal increments of time. The envelope generating circuit comprises a constant current source for charging a capacitor to generate a linearly increasing voltage signal upon the initial activation of any one or more keys of an electronic organ keyboard. A regulator circuit comprising an operational amplifier and a matched pair of transistors with one transistor connected into the feedback path for the operational amplifier generates an anti-logarithmic control signal in response to the linearly increasing voltage signal. The antilogarithmic control signal is used to control the amplification of a controlled amplifier to which music signals from the organ are passed.

Abstract: A touch responsive tonal envelope waveshape control system is provided for an electronic musical instrument which includes cooperating tone generating and keying circuits which are responsive to actuation of a key for initiating the generation and keying of a corresponding tone. The system of the invention includes encoding circuits responsive to the actuation of a key for producing encoded signals corresponding to the intensity of player actuation of the key and an amplitude control circuit responsive to these encoded intensity signals and cooperative with the keying circuits for controlling the peak amplitude of the tonal envelope waveshape in accordance with the intensity of player actuation of the key for initiating that tone.

Abstract: An integrated keyer system for use in electronic organs comprising a plurality of discrete integrated circuit chips each corresponding to two adjacent octaves of the keyboard and connected in series to accommodate the entire keyboard. The keyer system is adapted for use in multiplexed systems wherein the keyswitch closure information is encoded in a time division multiplexed data stream fed through a plurality of the keyer chips, which are connected in series. Each of the keyer chips includes a plurality of tone inputs and outputs and a divide-by-four circuit for lowering the tones in by two octaves. The keyer chips also include serial data inputs and outputs and a demultiplexer for demultiplexing the serial data stream at the serial data input to produce a plurality of control signals corresponding to keydown signals in the serial data stream, which are fed to the individual keyers.

Abstract: In an electronic musical instrument, two or more pulse signals different in phase are generated each having a frequency corresponding to the tonal pitch of an operated key, an envelope waveshape is read out upon every key operation, sampling is executed on the envelope waveshape by means of these pulse signals, and polarities of sample values are converted in reference to these pulse signals for generation of a corresponding musical tone waveshape. Minimized use of arithmetic circuits such as adders and multipliers greatly reduces production cost whilst assuring generation of a wide variety of colorful, noise-free musical tones. By addition of a slope conversion circuit, abrupt shift in the generated musical tone waveshapes can well be disappeared.

Abstract: An electronic musical instrument comprises a key on-off memory for storing the on-off state of the respective keys, and at a time counter for counting the lapse of time after release of the respective keys. The time counter inhibits generation of the musical tone signal corresponding to the key when the conditions that predetermined time is elapsed after the key release and that the key-off state is stored in the memory are satisfied. This inhibition is separately conducted with respect to the keys. Thus, it can remarkably prevent noise when the tone should not be produced.

Abstract: There is disclosed herein a music synthesizer which responds to a music note played by a music instrument. The synthesizer has an envelope generator which generates a control signal in relation to the input signal to control the loudness of the synthesized note. Also, the synthesizer has a pair of voltage controlled oscillators, one of which provides a signal having a frequency related to the frequency of the input note, and the other of which provides a signal having a frequency related to the frequency of the input signal offset by the ratio of the difference between a programmed note and a referenced note, such as A440. The programmed note is that note following the operation of a control switch. The synthesizer further includes a series of footpads which control various functions of the synthesizer, such as programming the programmed note, to allow the user to control the synthesized sound while playing an instrument.

Abstract: An electronic sound system especially effective with bell sounds synthesizes the approximate sound of each bell in a set of 49 switch operated bell sounds. The synthesizing is accomplished by utilizig an envelope generator for each partial of a group of 7 partials for each of the 49 sounds, in association with a single 73 note wave generator. The envelope generators for low partials of each group of 7 are slow attack, slow decay relatively long envelopes. The envelope generators for the high partials of the same group of 7 are fast attack, fast decay relatively short envelopes, and envelopes for certain intermediate partials are fast attack with combined short and long decay envelopes of intermediate length. There is a single wave generator for each of 73 tones, the wave generators having circuits interconnecting them with partials of common frequency of the various groups of 7 partials for the respective keys.

Abstract: An envelope is imposed on a sequence of binary waveform samples representing a musical waveform signal by repetitively summing selected ones of a group of scaled representations of each of the waveform samples of the form A/2.sup.m, A/2.sup.m+1 . . . A/2.sup.m+p, where A represents the magnitude of the waveform sample, p is a predetermined integer, and m is an integer changing by a factor of unity each time a predetermined number of the groups have been developed. The sum of each group of scaled representations differs from the sum of the preceding group by the factor A/2.sup.m+p whereby a staircase signal is produced amplitude modulating the musical waveform signal, the step size of the staircase signal charging each time said predetermined number of groups have been developed.

Abstract: A keying system provides selectable decay times for individual frequency components of a tone to be generated by an electronic organ having a top octave generator producing a multiplicity of rectangular wave signals, and a plurality of associated divider circuits. The keying system comprises a keying block having a plurality of keyer sections. Each keyer section has a first keyer channel comprising at least two MOSFET transistors which are connected in series. At least one keying section further comprises a second keyer channel similar to the first keyer channel, a voltage threshold circuit which has a selectable threshold and switching circuitry to select output signals from either the first or second keyer channel of the one keying section. Each channel of the keying block is connected between a supply voltage and a load resistor which is in turn connected to a reference potential.

Abstract: A keying system provides selectable decay times for individual components of a tone to be generated by an electronic organ having a top octave generator producing a multiplicity of rectangular wave signals, and a plurality of associated divider circuits. The keying system comprises a keyer block having a plurality of identical keying sections. Each keying section comprises at least two MOSFET transistors which are connected in series and the series combination is connected between a supply voltage and a load resistor. A multiple position switch is connected to each load resistor to selectively connect the load resistor to one of a plurality of biasing voltage supplies. Rectangular wave signals from the top octave generator and divider circuits are applied to the gate of one of the transistors in each of the identical keying sections of the keyer block.

Abstract: A harmony authorization detector (HAD) synthesizer electronically generates single audible musical notes in harmony with single original aural notes of a melody as the melody is played on an instrument by a single player. Thus the HAD functions as, in effect, a second instrument electronically operational in harmony with a manually played lead instrument. The HAD synthesizer is particularly useful with guitars although not so limited. When a lead electronic guitar is used in a solo situation playing one original note at a time, the HAD synthesizer will, for each string on each position of the guitar and with the aid of a group of tone decoders, electronically detect the single fundamental note played by the guitarist and will authorize the emission of a preset, predetermined electronically generated synthesized single harmony note e.g. a third, fifth, seventh, etc. based on the fundamental of the single note played by the lead guitarist.

Abstract: An envelope signal generator which has a key depression/release signal generator for producing different output levels in response to key depression and key release, a switching circuit which is set to a first output level upon key depression and set to a second output level when the stored output level of an analog memory has reached a certain value, a preset circuit for outputting at least a level setting voltage and first and second time constant setting voltages relating to an envelope, a priority selector which is supplied with the key depression/release signal generator output, the switching circuit output and the level setting voltage and selects them in a predetermined order of priority, a first circuit for converting into a current the output from a voltage controlled amplifier supplied with the analog memory output and controlled by the first time constant setting voltage, a second circuit for converting into a current the output from a voltage controlled amplifier supplied with the analog memory ou

Abstract: A musical waveshape processing system for an electronic musical instrument in which time-division time slots are set corresponding to a plurality of channels for producing notes selected on keyboards of the electronic musical instrument and the notes are each produced by repeatedly calculating the musical waveshape amplitude value of each channel in each time-division time slot. A musical waveshape calculator is provided which calculates the musical waveshape amplitude value as f(t)=at.sup.2 +bt+c based on waveshape data a, b and c and address information t. A multiplier is provided by which the value of an envelope synchronized with the time-division time slot is multiplied by the waveshape data a, b and c.

Abstract: In a digital electronic organ or the like external waves of controllable duty cycle are used to control the on time of a field effect transistor (FET) through which a capacitor is charged. A similar rectangular wave of controllable duty cycle is applied to a second FET to control the on time thereof for controlling the discharge of said capacitor. The state of charge of said capacitor is used to control the conductivity of yet another FET through which a desired frequency is conducted to effect enveloping of such frequency with the desired attack and decay characteristics.

Abstract: An electronic musical instrument using continuous tone generators capable of simulating the sounds of a conventional acoustical piano. The instrument includes a gating circuit featuring a timed switch travel circuit having a double-time constant for improved control of the dynamic range from the keyboard, and a soft pedal controlling the keying voltage to produce more realistic emulation of the dynamic effects of an acoustical piano. The gating circuit produces a double-time-constant envelope of nearly harmonically related signals for a more realistic piano timbre. The tone spectrum is also controlled as a function of signal level by means of a resistor matrix feeding selected inputs of an active ladder filter, in order to reproduce timbre variation with dynamic level.

Abstract: An electronic musical instrument is provided with a keyboard which may comprise one or more keyboard sections. Plural instrument voices are stored in memory for each section of the instrument keyboard. Each stored voice comprises a set of plural multiple bit digital words. A composite audible tone corresponding to an active key comprises varying combinations of component signals derived from the stored voices. The decay pattern of the composite audible tone is divided into successive time zones. The durations of the zones may vary. For each zone, the amplitude of at least one of the component signals of the composite tone is caused to decay while the amplitudes of the remaining component signals are either not modulated or are maintained at zero. The rate of decay of the amplitude of a component signal, hence the duration of a particular time zone, may be made a function of the keyboard section associated with the active key. In an alternative embodiment, the instrument voices are not stored in memory.

Abstract: An electronic music synthesizer capable of simulating a wide variety of musical effects, wherein the settings which create the various effects are hard wired on a plurality of selectable circuit boards so that programming of the instrument can be accomplished by the player with minimum effort. The synthesizer encodes a plurality of keys on the keyboard and selects a tone from the tone generator corresponding to the depressed key. This tone is fed through a chain of dividers to create the needed footages, which are then fed to voicing cards that create the different tone sources for the synthesizer. These tone sources are fed into a state variable active filter which modifies the timbre of the tone sources in order to achieve the desired frequency-related effects.

Abstract: An electronic musical instrument for producing a vocal sound signal comprising a musical tone signal generator connected to a passing circuit for passing a musical tone signal under the selection of a key. A formant filter is connected in the passing circuit and includes a plurality of filters connected in parallel to one another. A control system is operative to produce two output signals in the passing circuit after the formant filter in sequence upon operation of the key, one of the output signals being a vowel sound and the other a consonant sound.

Abstract: The present invention is a two-part apparatus for producing note attack and decay in a conventional electronic musical instrument. Either part of the invention may be used independently of the other; however, at present the combined use is preferred. In part one, there is provided an eight state counter clocked at a rate equal to the note generator cycle and a digital magnitude comparator. The inputs (A) from the eight state counter are compared to the attack and decay scale factor inputs (B) by the comparator. The A>B,A=B functions are generated by the comparator in combination with an OR gate. The OR gate output and the sample gating signal from the conventional musical instrument are applied to an AND gate which outputs a modulated sample gating signal. In part two, the modulated sample gating signal of part one is subpulsed individually by two subpulses.

Abstract: A data encoder for use with a time multiplexed electronic organ or the like comprises a multiple stage shift register, means for simultaneously loading a predetermined pattern of logic bits in the shift register in response to a key down representative data pulse and means for coupling the output of the shift register to one of the data channels of the organ. In a first mode, the data encoder is operable as a fill-note generator wherein the shift register is loaded in response to an upper manual key down representative data pulse and lower manual key down representative data pulses are coupled to the upper manual data channel of the organ according to the output of the shift register. In a second mode, the data encoder is operable as a chimes generator wherein the shift register is loaded in response to an upper manual key down representative data pulse and the output of the shift register is coupled to the upper manual data channel of the organ.

Abstract: A circuit for generating a percussion envelope for use in electronic organs and similar electronic keyboard instruments wherein the envelope has an attack overshoot, a long decay, and a snub decay when the key is released. A velocity sensing feature is included, whereby the force with which the key is struck determines the amount of capacitor discharge, and the voltage remaining on the capacitor is compared with the amplitude of the attack portion of the envelope such that decay is initiated when a compare condition is reached. A second comparator sets the amplitude at which the envelope undergoes transition from a fast decay to the normal long decay. The timing for the attack and three decay portions of the envelope are independently controlled by means of four clock driven electronic gate circuits which incrementally charge and discharge the main timing capacitor. The gate circuits include a pair of serially connected field effect transistors having a capacitor connected at their juncture.

Abstract: A limited number of top octave synthesizer tone generating circuits for producing various tones are used in an electronic organ. Each of the top octave synthesizer circuits is capable of producing any tone which can be produced by the organ. An assignment circuit is employed to assign different ones of the top octave synthesizers to produce the tones represented by different key closures. Because of the limited number of tone generator circuits employed, it is possible under some circumstances to attempt to cause the organ system to produce root tone outputs in excess of the number of top octave synthesizer circuits used in the system. When this occurs, a root tone for a new note is assigned to the top octave synthesizer circuit which is farthest into its decay mode of operation, thereby terminating the tone previously produced by that top octave synthesizer circuit earlier than would be the case if the full decay of that tone were permitted to take place.

Abstract: An envelope waveform generator for electronic musical instruments which has a circuit for converting envelope clock pulses into a clock frequency having the pulse density corresponding to a musical sound frequency to vary the envelope speed in response to the musical sound frequency, a circuit for converting the output clock pulse from the abovesaid circuit into a clock frequency having the pulse density corresponding to an attack, sustain or release of a key switch to thereby control the speed of the attack and release, a pulse density function generator composed of a function generator whose output changes at every constant number of output clock pulses from the second-mentioned circuit and a pulse density multiplier for controlling the clock pulse density with the output from the function generator, and an envelope counter for counting the output pulses from the pulse density function generator to provide the sum of the pulse density functions as an envelope waveform.

Abstract: A large scale integrated circuit chip is provided with internal tone generators and digital attack and decay features interconnected with external capacitors for controlling the attack and decay of tones. External diodes are wired to the chip and to the external capacitors and have a circuit completed by a damper switch. According to the position of the switch the capacitors will discharge slowly for long sustain of tones, or will discharge very rapidly through an additional discharge path on the chip upon key release to produce very rapid decay.

Abstract: In a digital touch response circuit or touch signal processing circuit for producing a control waveform signal to control a musical tone to be produced in response to a player's finger touch on a key, digital touch data representing a player's instantaneous finger touch on a key is compared in a comparison circuit with digital output data from an operation circuit such as an adder circuit, which varies at a rate as the result of addition of a rate value to input data applied to the adder. A selection circuit is responsive to the comparison circuit to selectively couple the output data of the adder and the digital touch data to a temporary memory circuit such as shift registers. The output data from the memory circuit is coupled to the adder as the input data thereto.

Abstract: A time-shared electronic musical instrument is provided with programmable wave-form generating and tone coloring circuits in order to maintain the musical characteristics regardless of pitch. The circuits comprise programmable keyers and wave-shapers, programmable envelope generators, programmable filters, and a programmable voicing selection circuit, in all of which certain characteristics of the output signal are tailored to the frequency of the musical tone.

Abstract: An envelope generator is provided with a count circuit the count value of which is varied through addition or subtraction or combination thereof, and a conversion circuit which operates to convert the count value into amplitude data, so as to generate an envelope having a shape corresponding to variations with time of the count value. According to one aspect of the invention, the count circuit is a circuit which carries out computation for exponentially varying the count value through polygonal line approximation, so as to form an envelope of exponential characteristic. According to another aspect of the invention, the conversion circuit is a memory which has stored amplitude data corresponding to count values in advance so as to convert count values in the last linear region of the envelope obtained by the polygonal line approximation into amplitude data in exponential relation and to convert count values contained in the remaining polygonal line regions into amplitude data in linear relation.

Abstract: A CPU of a computer, or preferably a so-called microprocessor controls the tone waveshape generation. A tone generator unit, an instrument keyboard unit, a tone quality control unit are connected to a common data bus to which the CPU and the associated memories are also connected. Thus, the tone generator unit may be considered as a terminal unit of a computer system. Hence, the freedom in selecting the algorithm for generating a waveshape and the freedom in selecting and changing the parameters related to the waveshape generation are substantially increased. And therefore a gradually changing waveshape is very easily generated in one embodiment of this invention.

Abstract: An envelope generator comprises a counting circuit and counting control means capable of controlling a counting mode of the counting circuit, i.e., operation and non-operation of the counting circuit, counting speed, addition and subtraction etc., in accordance with an envelope shape to be obtained. There are various predetermined counting modes corresponding to different envelope shapes and the envelope generator includes selection means for causing the counting control means to select a desired one of the counting modes.

Abstract: The disclosure describes improved apparatus for synthesizing an audible note from its volume, attack-decay envelope and waveshape characteristics. By employing multiplying analog-to-digital converters, the characteristics can be rapidly generated and combined in real time, thereby enabling the use of the synthesis in performing instruments.

Abstract: A polyphonic electronic music synthesizer reproduces in real time complex sounds representative of musical instruments and other musical and non-musical sounds from an above-audio frequency signal. The synthesizer includes a sampling circuit for repetitively sampling the high frequency signal to thereby provide a series of samples, successive ones of the samples being produced by sampling the relatively high frequency signal at a rate of approximately once per cycle at instantaneous points in the cycle which are progressively displaced from the previously sampled points. A storage mechanism sequentially stores the samples, and a mechanism is provided for sequentially recombining each of the sample in real time to thereby produce the selected waveform at the desired audio frequency. Preferably, the sampling circuit is implemented digitally.

Abstract: In an electronic organ system having a plurality of tone generators one for each note to be sounded, and a time constant circuit for establishing first and second decay characteristics for each note, the first of which has a longer decay period than the second, a key-down detector for sensing the operated condition of any key of the keyboard, and a circuit operative in response to the key-down detector to cause the sounded notes to have the longer decay characteristic so long as any key of the keyboard is depressed and to cause the sounded notes to have the shorter decay characteristic when all keys are released, for producing a pseudo-reverberation effect.

Abstract: In a circuit for simulating the sound produced when a stringed instrument, such as a bass viol, is plucked, square wave signals of different frequencies from a tone generator are combined to produce a synthesized sawtooth waveform which is applied to a low pass filter to remove the extremely high order harmonics, and then applied to an amplifier the gain of which is controlled in accordance with an envelope signal having a fast attack and a relatively slow decay. The resulting amplified signal is applied to an off-center-biased amplifier which alters the harmonic content of the output signal as a function of decay time such that when the signal is acoustically reproduced it closely simulates the sound produced when a bass viol string is plucked.

Abstract: An envelope generator for use in an electronic instrument generates an envelope waveshape control voltage having separate attack, first decay and second decay sections. The control voltage representing each waveshape section is derived from a separate voltage divider network. The divider networks are connected in series, with separate voltages supplied to the ends and junctions thereof. These supplied voltages correspond to the initial, attack, sustain and final voltage levels of the generated control voltage. The output nodes of the separate divider networks are accessed at different clock rates.A scanning circuit sequentially enables consecutive pairs of gates associated with each divided voltage output node. These gates alternately are connected to separate first and second output lines which provide divided voltages from adjacent gate pairs to opposite ends of an interpolation circuit. This circuit interpolates the provided voltages to derive the envelope waveshape control voltage.

Abstract: A tone generator system for an electronic organ which is capable of being fabricated into an LSI structure and receives a saw-tooth wave or staircase wave as an input thereto comprises a frequency divider for the saw-tooth wave or staircase wave including a ladder resistor network and a complementary MOS FET devices, an analog switch having a wide dynamic range and a high linearity in input-output transfer characteristic constructed by MOS FET devices to serve as an indirect keying means, a sustain means including a novel structure of a variable impedance element which is constructed to control a channel current in a MOS FET device by varying a potential distribution in a source region, and an impedance converter constructed by complementary MOS FET devices and free from a D.C. level shift. With the above arrangement a tone generator system of high quality for an electronic organ is provided.

Abstract: An electronic musical instrument comprises a circuit for generating a stepwise envelope waveform which modulates a musical tone waveform signal, a detecting circuit for detecting the phase of the musical tone waveform signal where the amplitude of the musical tone waveform signal becomes the zero level, and a control circuit for bringing the amplitude of the envelope waveform to be at the zero level in synchronization with the detection of that phase of the tone signal by the detecting circuit if generation of the envelope waveform is to be finished, thereby to eliminate the generation of click sounds.

Abstract: A touch responsive unit for a keyboard electronic musical instrument. A high frequency signal source is connected to one plate of a normally open circuited variable capacitor. The other plate of the variable capacitor being mechanically connected to a force transferring mechanism and electrically connected to a circuit means for generating a control voltage envelope. The depressive force applied to the key through the transfer mechanism causes the capacitor plates to overlap. The degree of area overlap is proportional to the depressive force and determines the capacitance value. As the plate area overlap increases, the capacitance value increases and the peak amplitude of the high frequency source passed by the capacitor increases. The control voltage envelope of the circuit means is applied to a standard keyer circuit to amplitude modulate a tone signal source corresponding to the selected key. The slope or decay rate of the control voltage envelope is regulated by the circuit means.

Abstract: Disclosed is a digital arpeggio system for an electronic organ that through the use of digital techniques permits arpeggios, note sequences as well as strum, multi, organ, and normal modes of operation to be played automatically. Two counters scan by counting through an 8.times.8 matrix of 64 words covering the 61 notes of an organ in rapid sequence upon the playing of one or more organ keys. Each word is fed to a corresponding one of 61 decoders, one for each note of the keyboard. If a corresponding key has been played, the decoder provides a signal to a corresponding pulser circuit which enables a corresponding keyer to transmit an audio signal from an audio oscillator corresponding to the played key to an output system and loudspeaker. The two counters are stopped by a clock control while the note is sounded and then the counters are enabled by the counter control to continue counting through the matrix until the next actuated key is located.

Abstract: A digital keying system for an electronic musical instrument, such as an electronic organ, comprises a digital percussion generator which synchronizes the operation of a variable attentuator with the zero crossings of a sine wave signal applied to the input of the attenuator from a waveform generator. Pulses from a rhythm generator are applied to a coincidence gating circuit along with pulses corresponding the zero crossings of the sine wave signal from the waveform generator to synchronize the stepped operation of the variable attenuator with the zero crossings of the sine wave signal applied to it.

Abstract: The inventive circuitry extends the harmonic content of musical tones produced by a computor organ of the type disclosed in U.S. Pat. No. 3,809,786. A memory stores values of an algebraic approximation of the summation of the amplitudes of a set of Fourier components of order higher than those separately evaluated by the computor organ itself. As each musical waveshape sample point amplitude is computed by the computor organ, the stored summation approximation value for the corresponding sample point is accessed from the memory. This accessed value is appropriately scaled, and is added to the sum of the lower order Fourier component contributions that are calculated by the computor organ. The resultant sample point amplitudes are converted to musical tones in real time. In an illustrative embodiment, musical tones having the spectral content of a sawtooth wave are produced.

Abstract: A sustained repeat control in a digital polyphonic synthesizer for gradually decreasing the amplitude of one or more notes generated repetitively in response to operation of a single key. The sustained repeat control includes a digital register storing a plurality of control words in digitally coded form, there being one control word assigned to each note being generated at any one time. Each word includes bits coded to indicate the current relative amplitude of the associated note. When a key is depressd, the control word or words for the note or notes assigned to that key have bits initialized to a predetermined value. When the key is released the amplitude values represented by the bits are counted down periodically. The bits in turn control the amplitude of the repetitively generated notes, a zero detector terminating the operation when the bits are decremented to zero.

Abstract: This invention relates to an electronic musical instrument which comprises a waveshape computation cycle, a waveshape transmission cycle and an envelope load output. In the waveshape computation cycle, a musical waveshape is obtained in the form of the accumulation of the products of the nth powers of the fundamental frequency of a cosine wave and coefficients A.sub.n indicating harmonic components of a musical note in certain relationship.

Abstract: An envelope generator comprises a counting circuit and counting control means capable of controlling a counting mode of the counting circuit, i.e., operation and non-operation of the counting circuit, counting speed, addition and subtraction etc., in accordance with an envelope shape to be obtained. There are various predetermined counting modes corresponding to different envelope shapes and the envelope generator includes selection means for causing the counting control means to select a desired one of the counting modes.