Abstract: In an electronic musical instrument of a digital processing type, an operation of a key causes the generation of a digital value corresponding to the operated key and a tone having a frequency determined by that digital value is produced. The instrument comprises a key assigner which assigns the operated keys from among a large number of keys to a small number of channels, which small number is a number of maximum available tones to be produced simultaneously. The instrument further comprises a modifying value generator for generating modifying values for the respective channels, the value being a first value upon key operation and subsequently varying to a second value to provide an attack pitch fluctuation effect. The key assigner and the modifying value generator are of a time division multiplexing type with the channels being defined by the corresponding time slots.

Abstract: A reverberation effect is produced in a musical tone generator of the type in which waveshape data points are sequentially and repetitively read out of a memory at a rate corresponding to the fundamental pitch of a musical tone. The reverberation effect is obtained by having a second memory storing waveshape points which are read out simultaneous with those from the first memory. The second data set is scaled by the ADSR envelope function and at selected echo time spacings is pointwise added to the data stored in the first memory. The data read out of the first memory is converted to an analog musical signal having a reverberation effect during the attack or release phase of the musical tone.

Abstract: An electronic organ, particularly of the institutional type employing classical voicing, having Swell and Great manuals as well as a full pedalboard wherein the manuals and pedalboard are multiplexed simultaneously to produce a plurality of synchronized serial data streams. Intermanual coupling is accomplished by connecting the data stream from one manual to the footage generation cirlcuit of another manual, and footages are generated for each manual by utilizing tapped shift registers introducing controlled amounts of delay of the keyboard data before demultiplexing thereof. There is a bank of demultiplexer-keyers for each voice, such as flutes, principals, complex and percussion, which receive the serial data streams from one or more of the footage generators. The demultiplexer-keyers are supplied with tones and function to demultiplex the serial data streams and provide to the voicing circuitry tones selected in accordance with the keydown pulses in the serial data streams.

Abstract: A waveform storage and generating system is disclosed in which at least two waveforms are stored. Values of the first waveform are sequentially read out, and smoothing to eliminate step noise is performed. In order to smoothly shift to reading out the second waveform, one or more transitional waveforms are derived which represent amplitude values between the first and second waveforms. The process of reading out the first, transitional, and second waveforms to provide a smooth transition is referred to as cross-fading. Several embodiments, including a microprocessor oriented system are disclosed.

Abstract: An electronic musical instrument of the type producing pipe organ-like sounds including a circuit for simulating wind noise by causing a random perturbation from the nominal frequency of tune, which an organ flue pipe exhibits when sounding, through the use of digital noise generators which are utilized to approximate an analog white or random noise source. The digital noise generators produce digital noise signals which are used to frequency modulate the instrument tone generator to produce substantially random perturbations in tbe generator output signal frequency. The present invention may be used with musical instruments having a single tone generator system composed of either a multiplicity of oscillators with a vibrato input, or a top octave frequency generator integrated circuit and a single oscillator with a vibrato input, or a transposer system.

Abstract: For the purpose of sequentially varying a tone pitch of a generated musical tone, a variation information generator is provided which is operable by a performer to generate a variation information designating an arvitrary variation rate of the tone pitch. An operation circuit is provided for producing a modified frequency information in response to the variation information and a frequency information representing a tone pitch regarding a depressed key. The modified frequency information is supplied to a musical tone signal generator and the output thereof is applied to a sound system for generating the musical tone, thereby obtaining a musical effect similar to glissando or portamento and having an arbitrary variation rate.

Abstract: A two-phase, period-proportional voltage-controlled oscillator circuit is provided for clocking an analog delay line which can be used, for example, in an electronic musical instrument. The voltage-controlled oscillator circuit provides two clock output signals of opposite phase and having a period directly proportional to the control voltage, i.e., the frequency of the two clock signals is inversely proportional to the control voltage. Since the delay provided by the analog delay line is directly proportional to the period of the clock signals, the delay is directly proportional to the control voltage thereby eliminating a source of distortion in a delay modulation system.

Abstract: A detuning control circuit is provided for producing a pitch variation effect in an electronic musical instrument. The instrument includes at least one integrated circuit tone generator chip having at least one tone generator and a detuning circuit responsive to a predetermined detuning control signal for detuning the signals produced by the tone generator. The detuning control circuit comprises a detuning control signalling circuit for producing a predetermined detuning control signal and for selectively applying the predetermined detuning control signal to the detuning circuit of the tone generator chip so as to produce a predetermined pitch variation effect.

Abstract: A keyboard operated electronic musical instrument in which a number of tone generators are assigned to actuated keyswitches. When a keyswitch is actuated, a tone generator is assigned with a musical waveshape selected from a library of waveshapes which are ordered in a predetermined arrangement. The assignment of waveshapes is made in a priority order according to the musical frequencies associated with the actuated keyswitches so that a chorus effect is obtained in which each note of a group of simultaneous notes has its own tone color. The assignment of waveshapes is made in an adaptive manner so that the melody line retains its own distinctive sound even when the number of notes played simultaneously on a keyboard changes. Vibrato effects can selectively be applied to any of the set of waveshapes.

Abstract: A keyboard operated musical instrument with portamento effect in which the portamento keyboard consists 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 or changed along the portamento keyboard. The frequency numbers are utilized to control the pitches of tones generated by the musical instrument.

Abstract: An electronic musical instrument capable of providing automatic bass and chord accompaniments, either in accordance with a program prepared by the player or in immediate response to the depressing of a minimum number of keys on lower and pedal keyboards. The programmed accompaniments proceed sequentially (in steps) with successive measures of accompaniment data being read from a memory. By making some of these measures blank in introducing the accompaniment data into the memory, therefore, the player can play desired bass and chord accompaniments by direct key depression during the blank measures. In an alternative embodiment the production of the programmed accompaniments is automatically inhibited during the production of key-responsive accompaniments, thereby enabling the player to override the programmed accompaniments at any time.

Abstract: A manually operated switch located on an electric guitar controls a remotely located tuning device through the existing guitar cable. Preferably, the switch is located in an adaptor which plugs into the audio output jack of the guitar and into which is plugged the guitar cable. Circuitry associated with the switch sends a control signal on the audio cable and circuitry located adjacent the tuner interprets the control signal for controlling the tuner.

Abstract: An electronic musical instrument wherein depression of a key entails the discharge of a primary capacitor which is connected to the inverting input of an operational amplifier whose output is connected with a second capacitor serving to supply envelope control voltage signals to an analog switch which connects a tone signal generator with a tone processing unit. The extent to which the primary capacitor discharges depends on the speed of movement of the key from non-depressed to depressed position, and the intensity of residual voltage of the partially discharged primary capacitor determines the intensity of the envelope control voltage signal. The speed at which the second capacitor discharges can be regulated to produce sustain or banjo effects. The second capacitor is in series with a resistor in a feedback conduit connecting the output and the input of the operational amplifier.

Abstract: The present invention relates to economically fabricated means for the generation and processing, member selection, and acoustic radiation of pluralities of individual tone currents originating from at least one high frequency source and formed by note-information temporarily transferred through key depression, from permanent electronic memories to temporary memories in small numbers of standard tone units, in precise duplication of properties of pipe organ sound.There is described an electronic transfer organ for duplicating twenty-six known properties of pipe organ sound. The illustrative, inventive instrument employs completely standardized circuitry except for automatically programmable memories for each organ voice, which contain all the information required to form, switch and variously decouple all the notes in that voice.

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: Room acoustics simulation is achieved by digitally defining delay and weighting parameters and generating sampled analog signal responses. In the early portion of a response term an accurate impulse response is provided and subsequently high echo density is simulated using sampled analog signal Schroeder sections. A sampled data analog signal device is used which employs charge transfer devices as programmable delay media, multiplying digital to analog converters to generate weighting of the analog signal and a general purpose microprocessor as a parameter calculator. The early impulse response characteristic is accomplished by providing a time domain finite impulse response (FIR) section in a transversal filter arrangement which directly feeds to an ultimate output and to parallel comb filter sections which in turn input to at least one all pass section of the so-called Schroeder configuration. The charge transfer devices are employed as programmable delays to propagate the analog signals.

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 electronic tone generator capable of providing improved musical and tone quality by providing a primary melody and a secondary melody such as an accompaniment or the like is provided. The electronic tone generator of the instant invention is characterized by the use of a primary electronic scale generator circuit for producing a primary scale signal representative of a primary melody scale and a secondary electronic scale generator circuit for producing a secondary scale signal that is representative of a secondary melody and that is distinct from the primary scale signal. The primary scale signal and second scale signal are respectively shaped and summed and thereafter applied to an electro-acoustic transducer in order to produce music having a primary melody and secondary melody of considerable musical quality.

Abstract: A circuit for generating alternating repeat keying signals in an electronic keyboard musical instrument includes a clock, a logic circuit responsive to the keys of the instrument and to the clock for producing an alternating sequence of logic signals corresponding to each of the keys, the phase of the sequence corresponding to each undepressed key being the same as the phase of the sequence corresponding to the previous key and the phase of the sequence corresponding to each depressed key being opposite that of the phase of the sequence corresponding to the previous key and a plurality of output gates each developing a keying signal in response to the depression of a respective one of the keys and the logic signals of the corresponding sequence assuming a predetermined state.

Abstract: A sequence generator system is disclosed for use in an electronic musical instrument wherein scanning circuits scan the instrument and produce a serial data stream corresponding to notes played on the instrument. The sequence generator system comprises sequence generating circuits responsive to the serial data stream for generating a further, predetermined data sequence and data steering circuits for receiving the serial data stream and for normally steering said serial data stream to a data output. Actuation of the system causes the data steering circuits to substitute the predetermined data sequence produced by the sequence generating circuits for the serial data stream at the data output.

Abstract: An automatic accompaniment apparatus which has an auto-bass circuit and an auto-arpeggio circuit. In the auto-bass circuit, note information concerning one kind of code is stored in a memory (ROM), and a code signal is detected from depressed key information in a code detector, and in a note converter a note signal from the memory is converted by the code signal to a note signal corresponding to the kind of code, whereby note signals of various kinds of codes are generated. In the auto-arpeggio circuit, note information concerning one kind of code is stored in a memory (ROM), and a code signal is detected from depressed key information in a code detector, and in a note converter a note signal from the memory is converted by the code signal to a note signal corresponding to the kind of code. The note signal is added with a root signal from the code detector, and by the added output, a scale signal is selectively obtained, which scale signal is frequency divided by an octave signal from the memory.

Abstract: A device for electronically simulating vibrato and tremulant effects and the radiation effects produced by a rotary loudspeaker with the aid of two loudspeakers, in which a musical tone signal is applied to a variable delay device associated with one of the loudspeakers. The frequency modulated signal produced by the variable delay device is also subjected to amplitude modulation, controlled in synchronism with the variable delay device, and the resulting composite signal applied to the other loudspeaker. Additionally, the high frequency components of the frequency modulated signal from the variable delay device are summed, in and out of phase relationship, with the composite amplitude modulated signal to simulate the effect of a rotating high frequency horn radiator.

Abstract: A device for electronically modulating a musical tone signal to produce substantially the radiation effects produced by a rotary loudspeaker with the aid of two loudspeakers, in which circuit an amplitude modulator is associated with one loudspeaker and a variable delay device is associated with the other loudspeaker, the musical tone signal being applied to both the amplitude modulator and the variable delay device, and both the variable delay device and the amplitude modulator being modulated synchronously by a sub-audio frequency modulating signal.

Abstract: An electronic musical instrument having a fret board and a plurality of conductive frets may be coupled to a resistance ladder of discrete resistive elements. A conductive wire or a plurality of such wires selectively making contact with at least one of the conductive frets forms, together with the resistance ladder, part of a tone generating circuit. The circuit includes an oscillator which generates a tone in response to the conductive fret with which the wire makes contact. The circuit may also include a wave shaping circuit which selectively alters the shape of the generated tone and through a series of gradations alters its operating characteristics from that of a full wave rectifier to a linear voltage follower. Another embodiment modulates the phase of the generated tone by exploiting the dynamic impedance of a diode. One or more unique pressure sensitive touch pads may be employed for a glissando effect and/or for volume and/or tone glides.

Abstract: In an electronic musical instrument which is arranged to produce musical tones belonging to the selected one of many different types of musical instruments and having a number of player-operable selection keys respectively corresponding to the number of types of musical instrument sounds desired, the improvement wherein means is provided for generating a sample tone belonging to that type of musical instrument specified by one of the above-mentioned selection keys at a prescribed pitch and period simply by depressing only once a particular selection key, without taking the trouble of successively depressing individual performance keys, thereby facilitating the selection of a desired type of musical instrument by the player.

Abstract: A potentiometer comprises a support member having first and second support regions and an intermediate region located therebetween, a resistive member supported on the support member at the first support region thereof and having a longitudinal dimension extending transversely of a line from the first support region to the second support region, and a resilient contact member secured to the support member at the second support region and extending over the intermediate region and terminating superjacent the resistive member.

Abstract: An electronic rhythm generator which comprises a large read only memory having a plurality of rhythm patterns and rhythm break patterns programmed therein, player operated selector switches for selecting a rhythm pattern and a break pattern, scanning circuitry for sequentially addressing the memory to read out the stored rhythm pattern, and, when the break circuitry is activated, reading out the break pattern in place of or in addition to the rhythm pattern. The rhythm generator is contained on a single monolithic integrated circuit chip with the pattern selection being accomplished by an external multiplexer driven by an internally generated scan word. The break activation circuitry automatically corrects for improper matching of a rhythmically incompatible rhythm pattern and break pattern by either ignoring the break command or substituting a compatible break pattern in place of the selected break pattern.

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: A fill note generator for use in electronic musical instruments such as electronic organs which include a keyboard having a solo portion customarily played by the right hand and an accompaniment portion customarily played by the left hand, and wherein the respective solo and accompaniment portions may be on separate manuals or on a single manual. A multiplexer scans the keys of the solo portion of the keyboard and generates a time division multiplexed solo data stream having keydown signals in discrete time slots for each actuated key of the solo portion of the keyboard. The keys of the accompaniment portion of the keyboard are interconnected so as to form twelve sets corresponding to the twelve pitches of the chromatic scale wherein the keys in each set are connected to a common output.

Abstract: In an electrical tone generator apparatus is provided for automatically selecting one of a library of chord types which is closest to a chord fingered on a fretted string instrument. The closest decision is made by processing the fingered fret input data by a set of matched filters each of which corresponds to a member of the library of chord types. The chord type decision is made to correspond to the matched filter producing the maximum output response. The selection between chord types yielding equal responses is resolved by priority logic based upon the frequency of chord usage. A root note is chosen for each chord type. Note keying data is generated from the selected chord types which is transposed to the correct musical pitches in response to the chosen root note. The note keying data is grated by an automatic rhythm generator and the output is used to actuate electronic musical tone generators.

Abstract: A method of synthesizing a musical sound in which a fundamental waveform signal is produced which has a zero crossing point within one cycle period thereof and the phase of the zero crossing point is modulated by a modulation signal to provide a musical tone with a complex waveshape.

Abstract: An electronic musical keyboard instrument that is controlled by a digital processor. Key and stops/effects statuses are sampled, during successive time intervals, and read into random access memory associated with the digital processor. After manipulation and/or supplementation of the status information to effect implementation of various features, key-representative signals are read out to tone generation and voicing circuits.

Abstract: An electronic organ has a tone generating system for producing tones corresponding to notes of a musical scale. The tones and combinations thereof are selectable to provide different characteristics or "voices" which duplicate the various voices which are selectable on a pipe organ. The character of each such voice is determined by a single generator. The character of the output tone on a per manual basis is alterable by substituting or combining the outputs of different generators. The signal produced in this manner is sampled at a rate which translates it to an audio frequency.

Abstract: An expression means has been developed which can accentuate only a selected musical sound, e.g., melody, out of melody, accompaniment chord and bass sound generated in an electronic musical instrument and does not accentuate other sounds. The expression means of the present invention produces a first electric potential that will vary in response to an operation of an expression pedal and a second potential that will vary in response to a slow operation of the expression pedal though irresponsive to a quick operation of it. For gain control of amplifiers that deal with musical sounds required to be accentuated, said first potential is prepared, and for gain control of other amplifiers that deal with musical sounds free from accentuation, said second potential is prepared. Furthermore, the expression means of this invention employs changeover switches to realize arbitrary choice of the sounds to be accentuated.

Abstract: An electric mouth organ holder containing a microphone therewithin and comprising an outer shell upon which are supported radially outwardly projecting harmonicas and a central core section rotatable with respect to said outer shell. The harmonicas are rotatably juxtaposed adjacent to said central core section as desired with individual harmonicas of different keys or types being thereby operatively associated with said microphone.

Abstract: A timbre-select type electronic musical instrument in which the application of a sound effect unsuitable for the selected timbre is automatically blocked. This instrument includes means for detecting that a certain timbre is selected and means responsive to the signal from said detecting means for preventing the unsuitable effect for the timbre from being applied to a sound.

Abstract: In a musical instrument having one or more tone generators in which a plurality of data words corresponding to amplitudes of a corresponding number of evenly spaced points defining the waveform of an audio signal composed of a number of unified tones are generated by the combination of three master data sets. The three master data sets are computed separately from stored sets of even and odd harmonic coefficient values. The master data set values are combined using their symmetric properties and are transferred sequentially to a digital-to-analog converter in repetitive cycles at a rate proportional to the unison pitch of the corresponding keyboard note to produce the tone color of a combination of unified tones.

Abstract: A microcomputer based synthesizer having a digital keyboard, digital envelope generators, voltage controlled amplifiers and filters, and numerous potentiometer type presets is disclosed. The presets are scanned by the microcomputer, converted to digital form, stored for recall on demand in a non-volatile memory, converted to exponential form by use of a look-up table when required, and output to clamp-and-hold circuits associated with each voltage controlled circuit. Each preset sample and hold operation is followed by a scan of the keyboard to minimize the impact of the capture system on the keyboard scanning rate.

Abstract: The operation of the chorus generator of FIG. 3 may be summarized as follows. The generation of a realistic chorus tone depends upon the simultaneous amplitude and phase modulation of a tone signal which initially has little or no choral characteristics. When a tone signal generator is so modulated, the derived audio tone from a loudspeaker will exhibit choral characteristics. A random low frequency signal generator serves as an input to both the amplitude and phase modulation channels. The amplitude modulation signal is merely a suitably delayed replica of the low frequency signal. The phase modulation signal is derived from the low frequency signal by first modifying its amplitude excursions by means of a function generator and then filtering the derived signal by means of a suitable non-minimum phase shift filter.

Abstract: The disclosure describes improved apparatus for sampling a digitally-stored waveshape only at a rate 2.sup.N times the fundamental frequency of a note synthesized, where N is an integer. The apparatus includes a digital memory for storing a digital representation of the waveshape. A top octave synthesizer produces clock pulses at a rate 2.sup.N times the fundamental frequency of a desired note. An octave oscillator generates addresses for the digital memory in response to at least some of the clock pulses depending on the octave in which the desired note is located. A digital-to-analog converter converts the output from the digital memory into an analog signal suitable for sound production.

Abstract: An arpeggio system, utilizing bipolar digital logic devices in all control and sequencing functions, generates a variety of arpeggio and strum note patterns. A key operated switch enables a NOR logic note gate, or a series of octavely related note gates, and activates a system clock which causes a pulse to be transmitted along a chain of shift registers, one of which corresponds to each note of the organ. If a given note gate has been enabled when its corresponding shift register is pulsed, the note gate is triggered. When a note gate is triggered, the system clock pauses for a preselected interval allowing the signal from a corresponding tone generator to be sounded through an appropriate system of filters and amplifiers. The system clock can cause the shift registers to scan in the up, down, or up and then down directions. An octave priming device can permit the sounding of notes in higher octaves which correspond to notes actually played.

Abstract: An electronic keyboard instrument generates signals of frequencies respectively corresponding to keys by depressing the keys of a keyboard from a signal source, and reproduces a musical note corresponding to the generated signal. The frequency spectrum of an external signal is detected and used to control the frequency spectrum of the generated signal to cause the frequency spectrum of the generated signal to approximate that of the external signal.

Abstract: An electronic musical instrument is of a channel assignment type and simultaneously produces a plurality of tones in automatic arpeggio performance. For that purpose, the instrument incorporates a plurality of automatic arpeggio performance channels. An automatic arpeggio performance is carried out in accordance with an arpeggio pattern. In order to simultaneously produce a plurality of automatic arpeggio tones, the instrument assigns respective arpeggio composing tones for the plural arpeggio performance channels by using an arpeggio pattern for one-tone production and a change pattern obtained by adding change information to the arpeggio pattern. Thus an automatic performance of polyphonic arpeggio is realized.

Abstract: An electronic tone or note generator capable of providing improved musical and tone quality and special sound effects by mixing the outputs of a plurality of note-signal-producing circuits is provided. The electronic tone or note generator of the invention is characterized by the use of a primary electronic note circuit for producing a primary note signal which is a portion of a primary melody, and a secondary electronic note circuit for producing a secondary note signal that is musically related to the primary melody. The relationship between signals can be a time lag between the outputs of the two note signal circuits or a small difference in frequency between the signal outputs of the two note circuits. Additionally, each note signal circuit can output alternate notes of a continuing melody such that a note from one circuit may persist while the next note from the second circuit is played.

Abstract: An electronic sound generator is developed for generating a sound similar to that of ANGKLONG (Indonesian terms), which comprises a circuit for generating a series of consequtive rectangular waves. A plurality of envelope wave generation circuits each produce an envelope wave having the same repeating cycle as that of each said rectangular wave and, one or more sound source circuits are used for generating signals substantially equal to the output waves of angklong, circuits in each of which an output of a sound source circuit is modulated by the relevant envelop wave. A loudspeaker sounds the modulated signal as a musical sound. In a record embodiment the sound generator further comprises a first gate to which the modulated signal is directly applied, a second gate is connected in series with the volume and/or tone control circuit, means for opening said first and second gates alternatively and a means for combining the outputs of said first and second gates to provide a musical sound from the loudspeaker.

Abstract: An accompaniment system for an electronic musical instrument is selectively actuatable for producing accompaniment effects such as arpeggio in accordance with selectable notes or chords and with selectable rhythm patterns. The electronic musical instrument includes one or more conventional keyboards, a set of chord switches for selecting one of a plurality of predetermined chords and a set of rhythm switches for selecting one of a plurality of predetermined rhythm patterns, respectively. The accompaniment system includes a ROM containing note position signals arranged in a plurality of groups, each group corresponding to one of the selectable rhythm patterns. An electronic circuit selects one of the groups in response to activation of one of the rhythm pattern selector switches and sequentially combines each note position signal in the group with a chord displacement signal developed in response to actuation of one of the keyboard notes or chord selection switches.

Abstract: A circuit for producing a special effect, such as a sliding tone effect or a "Hawaiian Guitar" tonal effect, utilizes a coincidence gating circuit and a bi-stable flip-flop to control a time delay circuit connected to the tone generating circuit of an electronic organ. This circuit responds to the playing of two keys of the keyboard in a rolled chord fashion to cause an automatic detuning of the master oscillator of the tone generating circuit, so that the tones go one semi-tone flat for a short period of time and then glide back into proper tune as controlled by the characteristics of the time delay circuit.

Abstract: In an electronic musical instrument apparatus is provided for producing a noise-like signal suitable for a variety of musical effect such as the imitation of percussive musical instruments. A noise master data set is created repetitively and independently of tone generation by computing a Fourier algorithm using random values for the Fourier coefficients. The noise master data set is transferred to a noise tone register whose output is sequentially and repetitively read and converted to an analog noise signal. Formant circuitry is used to vary the noise signal's spectrum in a time variant manner and the frequency of an assigned variable frequency clock can be used to vary the spectral bandwidth of the output noise signal.

Abstract: An electronic musical instrument is of a type wherein a key depression brings forth the generation of a key code identifying the depressed key in a digital representation, and the key code designates the tone to be produced. Based on the single key code of the depressed key, there are produced plural key codes indicating plural tones which are in predetermined musical interval relation with the depressed key to constitude a chord. The original key code and the produced key codes are utilized one after another successively to perform an automatic arpeggio.

Abstract: In an electronic musical instrument, the keys of a keyboard are divided into a plurality of groups by octaves, and a wave generator is provided with a memory for storing constants corresponding to musical tone frequencies to be generated according to the notes includes in a desired group out of the plurality of group, an accumulator for repeatedly adding the constants read out of the memory, and a bit position shifting circuit for shifting the bit position of the data produced by the accumulator according to the octave range of a note to be produced, thereby to obtain the data varying repeatedly according to the frequency of a note to be produced, and to reduce the storing capacity of the memory when compared to the number of keys.