Abstract: An expression pedal assembly for a musical instrument with conventional electromechanical control means of the pedal being replaced by proximity control means. The pedal assembly is comprised of a casing which houses a proximity detector plate, a proximity detector circuit and may include an audio circuit compartment. Earth shielding of the bottom and walls of the casing is provided. A heel rest at one end of the pedal casing serves to provide the only support for a musician's foot and is so positioned to support the sole of the foot above the proximity device to provide the musician with swift and fluent control of a musical function controlled by the response of the proximity device to movement of said sole.

Abstract: A digital musical tone signal is generated in a first LSI selected by a chip select signal transferred from a CPU in accordance with a control signal transferred through a control bus from the CPU. Amplitude data and envelope data are transferred from a second LSI to the first LSI through data lines. In the first LSI, the digital musical tone signal amplitude- and envelope-controlled is transferred to an A/D converter where it is converted into an analog musical tone signal.

Abstract: An electronic musical instrument by which a performer can provide a musical accompaniment in different musical styles. The performer selects a desired musical style and plays on a standard keyboard in order to express a desired harmony. The instrument translates the keyboard playing into a chord type and root that defines the harmony expressed by the performer. A processor generates parameter signals defining a segment of music including a plurality of accompaniment notes arranged in the selected musical style and related harmonically to the selected chord type and root. Output circuitry converts the parameter signals to sound so that a performer of limited skill or musical knowledge can play an appropriately-styled accompaniment to a melody written in any one of a variety of musical keys.

Abstract: An apparatus for encoding and decoding musical signals in digital form employs conversion to the frequency domain. Discrete Fourier transform coefficients are calculated from time domain digital data at selected frequencies which are organized in sets of octavely related frequencies. Selecting frequencies in this manner greatly reduces the data rate by eliminating coefficients for many higher frequencies without a great loss of fidelity because the provision of a predetermined number of frequencies in each octave approximates the tonal response of the human ear. A further refinement is selection of frequencies to correspond to the frequencies of musical notes where the greatest energy can be expected.

Abstract: An electronic musical instrument comprises a tone generator which generates tone signals having tone pitches as designated by playing keys and tone properties as determined by control data signals applied thereto. A set of control data signals are provided in a digital format and delivered timewisely in serial form to manual setting units. The serial signals are converted into parallel signals and applied to the respective setting units for desired adjustment. The adjusted or non-adjusted parallel signals are converted back into serial signals and applied to the tone generator. Interpolator circuits are provided between the setting units and the tone generator to apply the latter control data signals whose values vary gradually even when the values of the signals from the setting units exhibit abrupt large changes from certain values to another.

Abstract: A duet interval data memory includes tables each of which corresponds to a particular chord type and prestores a plurality of duet interval data. One of the tables is selected in accordance with the type of a chord being played in a lower keyboard. A note interval between a root note of this chord and a melody note being played in an upper keyboard constitutes a relative note. The duet interval data is read from the selected table in response to this relative note. A calculator alters the melody note by a note interval corresponding to the read out duet interval data thereby producing data representative of a duet note. The tone of this duet note is sounded with the tone of the melody note whereby an automatic ensemble performance is realized.

Abstract: An electronic keyboard musical instrument comprising a multiplexed keyboard and a programmable microcomputer interfaced between the keyboard and a system of capture tone generators. The loading circuitry for the microcomputer, which is interposed between it and the keyboard multiplexer output, monitors the serial data stream and transmits only key change information to the microcomputer. The microcomputer controls the assignment and deassignment of tone generators for the accompaniment, solo and pedal manuals based on the key change information transmitted to it. Fill note information is taken from the captured accompaniment keyers and compared with the series of binary words for the current scan of the manuals in order to produce a keydown pulse when there is identity of pitch between the captured accompaniment tone generators and the scanning of the solo manual.

Abstract: A musical instrument is disclosed in which light beams striking a detector produce various tones and the loudness of the sounds produced is dependent upon the intensity of the light beam which can be changed by interrupting the beam or reflecting the light backwards to a detector situated next to the light source. A special amplifier circuit is provided which responds to both the amount of light beam interruption as well as the rapidity of interruption. The invention can be variously embodied in woodwind, string and percussion instruments and can also be used on a stage and controlled by moving dancers or musicians.

Abstract: Electronic circuits are provided for producing an electronic timbre modulation for effecting celeste or vibrato similar in sonic results to the well-known Leslie rotating speaker system. Electronic signals corresponding to audio tones are generated and are modified by appropriate filters. Three controlling oscillators are locked in exactly 120.degree. phase relation to one another and act through three voltage controlled oscillators respectively to modulate three bucket brigade circuits through which said modified electronic signals are passed substantially in parallel. A roving band pass filter further modulates those of said electronic signals corresponding to flute tones to simulate other aspects of a Leslie speaker system.

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 musical tone is synthesized by frequency modulation which realizes a desired fixed formant. A first accumulator repeatedly adds a constant corresponding to a center frequency of the fixed formant at a regular time interval to generate phase angle data of a carrier. A second accumulator repeatedly adds a constant corresponding to a fundamental frequency of a selected note at a regular time interval to output a carry out signal each time the accumulated value has exceeded a predetermined modulo number. By resetting the first accumulator repeatedly by this carry out signal, the phase angle data of the carrier is brought into a harmonic relation with the fundamental frequency. By effecting frequency modulation using this phase angle data of the carrier and the fundamental or harmonic frequency of a selected note, a musical tone in which harmonic components of the selected note are controlled in accordance with the desired fixed formant is synthesized.

Abstract: An electronic musical instrument comprises a plurality of musical tone control units each having a tone waveform producing circuit, a volume envelope circuit, a filter circuit and other circuits. A given musical tone data can be preset in each musical tone control unit. Musical tone signals produced by the musical tone control units are synthesized to provide an effective musical tone.

Abstract: The present invention is a single channel string ensemble sound system for an electronic organ having a keyboard formed by a plurality of keys and a signal generating means responsive to the depression of the keys. The sound system comprises an electronic mixer, an amplifier, a first transducer and a second transducer, wherein the first transducer is driven by the output of the amplifier while the second transducer is driven approximately 180.degree. out of phase electronically by the same output, and wherein the second transducer is physically oriented in a plane approximately 90.degree. from the plane of the first transducer or speaker.

Abstract: An electronic musical instrument includes first and second ROM's addressable for producing respective two-bar musical patterns representing independent automatic rhythm and music style features. Both ROM's are operable in response to a common clock signal to facilitate synchronous operation thereof regardless of the order in which the two features are played. In particular, the states of a rhythm counter clocked by the clock signal are decoded for generating a first control code tracking the extent of completion of the two-bar automatic rhythm pattern, the first control code being used to initialize start-up of the music style pattern during a performance of the automatic rhythm feature to insure completion of the two musical patterns in time coincidence. Upon start-up of the automatic rhythm feature during a performance of the music style pattern, a second control code is calculated to initiate the automatic rhythm pattern to insure time coincidental completion of the two musical patterns.

Abstract: In a electronic musical instrument wherein a portamento is played by supplying the pitch voltage corresponding to a subsequently depressed key to a capacitor holding the pitch voltage corresponding to a previously depressed key, the charge and discharge currents of the capacitor corresponding to the difference between the two pitch voltages are controlled to vary exponentially thus changing exponentially the capacitor terminal voltage. The terminal voltage of the capacitor is applied to drive a voltage controlled oscillator to vary its oscillation frequency. To vary exponentially the terminal voltage of the capacitor, a mutual conductance converter is connected between the capacitor and a keyboard section and the output current from the mutual conductance converter is controlled by a control signal corresponding to the terminal voltage of the capacitor.

Abstract: Circuitry is provided for distorting an audio signal, useful in providing a "dirty" sound to an electric guitar simulating a vacuum tube amplification thereof. The circuit includes components for simultaneously changing the amount of distortion introduced by a clipping circuit and the amount of gain boost provided at a preselected narrow bandwidth. Addition of such gain boost leads both to increased clipping of the audio signal and to reduced frequency response, at both low and high frequencies. A separate volume control is provided for broad band gain adjustment. Independently operable control switches permit insertion or elimination of the distortion, and insertion or elimination of a brightness circuit boosting high frequency response of the circuit.

Abstract: In an electronic musical instrument, there are provided a main musical tone generator for producing a main musical tone and a submusical tone generator for producing a submusical tone different from the main musical tone. The main musical tone generator has a plurality of tone production channels smaller than a total number of keys, the assignment of key information data corresponding to a depressed key to the tone production channel is changed according to a performance mode. The tone production channels and the key information data corresponding to depressed keys are divided into at least two groups respectively in the case of performance mode. One group of the tone production channels is assigned to one group of the tone production channels to produce the main musical tone for an automatic accompaniment, whereas another group of the key information data is assigned to the remaining group to produce the main musical tone for melody.

Abstract: An electronic musical instrument comprises a plurality of key switches and a key switch scanning circuit for sequentially scanning said key switches at a predetermined speed to produce time division multiplexed key data signals representing the depressed states of respective keys. The instrument further comprises a time division multiplexed tone waveform generating circuit which generates tone signals on a time division basis and in synchronism with the scanning of said key switches, said tone signals consisting of waveform samples of all the notes, i.e. tone frequencies, that the instrument can generate, and means which delivers out the output signal from the time division multiplexed tone waveform generating circuit at the moments when said time division multiplexed key data signals arrive, thereby producing plurality of tone signals in a time division multiplexed manner.

Abstract: An electronic organ has a digital control circuit with a sampling circuit (3) which generates key identification signals (B) in the form of pulse series wherein the pulses denote the actuated keys (2) of the keyboard (1). Such pulses cause a tone selector or evaluating circuit (12) to transmit tone signals to a voicer circuit (15). A shift register (16, 116 or 216) is provided to delay the key identification signals so that the tone signals which the voicer circuit receives do not correspond to those normally expected on actuation of certain keys. The non-delayed key signal can be superimposed upon the delayed signal or signals (V1, V2) in a suitable summing circuit (17) to thus achieve transpositions, interval couplings and other tonal effects.

Abstract: In an electronic musical instrument, where a musical tone signal having a plurality of partial tone components in a predetermined bandwidth is produced by amplitude-modulating a carrier signal according to a time window signal, there is provided a control means which generates a control signal determining orders of partial tone components to be calculated. In accordance with the control signal the frequency of the carrier signal and the time width of the time window signal. This instrument makes it possible to freely select the frequency bandwidth of the calculated partial tone components, thereby producing a musical tone having a variety of tone colors.

Abstract: Tone amplitudes of signals which are generated in an electronic organ are converted into digital values and such values are cyclically memorized by a RAM storage at locations which are selected in accordance with a first function. The locations in the storage are then scanned in accordance with one or more second functions which differ from the first function in dependency on time, the thus ascertained or read-out digital values are thereupon converted into analog values, and the analog values are consolidated into processed tone signals. The second functions are or can be derived from the first function.

Abstract: An electronic reverberation system for use in an electronic musical instrument comprises a random access memory wherein two or more time delay channels are defined by address allocation in a controller circuit. An input analog signal is converted to digital signals by an analog-to-digital converter and the digital signals are processed by the controller into the time delay channels. The channels defined in the random access memory are of differing lengths which can be changed by switch settings. The controller sequentially retrieves stored digital data words from the random access memory channels in seriatum and couples each data word to a digital-to-analog converter. The analog output signal from the digital-to-analog converter is delayed in time by varying amounts due to the length of the channels in the random access memory. A portion of the delayed analog output signal contained in each channel is mixed with the input analog signal to produce a combined signal.

Abstract: A non-volatile memory system for an electronic musical instrument having a plurality of player actuatable instrument controls, comprises a readable, writable memory. The memory includes addressing inputs and data input/outputs. The data input/outputs are coupled with at least selected ones of the plurality of player actuatable instrument controls. Player actuatable memory controls are also provided for selecting either the memory or the selected ones of the player actuatable instrument controls for control of the instrument.

Abstract: A multiple octave generator system for providing tones in an electronic organ permits the production of both ensemble and celeste effects by providing the appropriate amounts of detuning among cascaded ranks of divide-by-two locked octave type tone generators. The generator system programs from the ranks adjacent octaves of generator into groups having slightly overall stretched tuning which, when combined with an unstretched rank, closely resemble pipe organ celeste tuning. This permits the celeste beat rate of the lower octaves to be increased to a more desirable rate without causing the beat rate of the upper octaves to become too fast.

Abstract: A manual control lever for plucked instruments supplied with electric sound amplification has a rest plate for the player's plucking hand. This rest plate is located above the strings and held by a lever arm which has rotary bearings, allowing a motion parallel to the top and further an up-and-down motion vertical to the top of the instrument. The parallel-to-the-top-motion provides the necessary movability when plucking the different strings of the instrument. The vertical-to-the-top-motion provides a continuous control of sound elements, preferably volume and timbre, through the fact that the mechanical means drive electronic members converting the mechanical movement or pressure into a continuous variation of voltage or current. The volume is controllable in two ranges: Firstly from zero to the normal level, and secondly from normal level to a maximum peak.

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 digital rectangular wave musical tone generator (10) activates a speaker (12) to produce sounds of aural quality similar to musical instruments, while varying the intensity of light output from a light-emitting diode (13). The intensity variations of this light controls the resistance of a photoresistor (16), which varies the power supplied to decorative lights by a power control device (19), thus varying the intensity of the decorative lights in synchronism with the sound.

Abstract: An electronic keyboard musical instrument comprising a multiplexed keyboard and a programmable microcomputer interfaced between the keyboard and a system of capture tone generators, and including means for causing phase locking between the tone generators. The loading circuitry for the microcomputer monitors the serial data stream and transmits only key change information to the microcomputer. The microcomputer controls the assignment and the assignment of tone generators for the accompaniment, solo and pedal manuals based on the key change information transmitted to it. In order to avoid cancellation between tones which are in octave or multiples thereof apart, the tone generators for each manual are phase locked with the other tone generators for that manual. Not only are the top octave synthesizers for each tone generator phase locked, but the divider strings are uniformly loaded so that they operate in identical states.

Abstract: A string chorus generator in an electronic musical instrument that accepts a single audio input signal, applies it to three separate delay lines, and provides delay modulated outputs to be used in producing an ensemble musical effect resembling a group of strings in a string orchestra. Each of the three delay line channels is identical and comprises an analog shift register driven by a high frequency voltage-controlled oscillator along with appropriate filters and buffers. The frequency of the voltage-controlled oscillator of each channel is controlled by the filtered output of a microprocessor, thereby providing precise control over the modulation of each voltage-controlled oscillator. The modulating waveshape is generated by using a lookup table within a microprocessor and comprises a sine wave of 6.25 Hz superimposed on another, larger amplitude, sine wave of 0.78 Hz.

Abstract: A multiple language electronic keyboard system is disclosed for generating and modifying musical note information. The system includes a plurality of manually activated switches arranged in a matrix of rows and columns with the switches sufficiently close to allow a single finger of the user to activate a plurality of switches in a single stroke. A decoder detects and distinguishes between a first language and a second language of distinct switch activation patterns. Musical note information is generated by a processor which receives information from the decoder concerning the location of each activated switch and the language detected by the decoder. The versatility of this system is further enhanced by the addition of envelope and tone generators and also by visual display devices. In the preferred embodiment the keyboard is arranged to positionally and operationally emulate a guitar fret board.

Abstract: A chord performing apparatus for an electronic organ with a chord-former, comprises control inputs for control signals defining the chord tone, and control inputs for control signals defining the chord type and control units which can be preset in accordance with a pattern of chord tones and chord types to be played and outputs which are scanned and controlled in the rhythm of the melody for performing the same function as the switch elements, connected with the control inputs of the chord-former.

Abstract: Simultaneously played notes on a keyboard are automatically provided with different voice timbres. The assignment of voices to notes is by relative frequency-scale position within the chord. If four or more notes are played, the notes are scanned along the musical scale and the three lowest notes played and the highest note are sounded in different voices with the solo voice assigned to the highest note. Assignment of voices occurs automatically when fewer than four keys are played. Time division multiplex digital logic signals representative of the played keys are applied to a memory circuit and a comparator circuit. If the information stored in the memory from the previous scan cycle is unchanged the comparator provides an enabling signal to a monostable and enable logic circuit. A priority selector circuit provides logic information to the monostable and enable logic circuit which outputs this information and information representative of the total number of keys played.

Abstract: A system for extracting the fundamental frequency or pitch of complex waves such as voice, musical instruments or other audio signals. Separate channels extract the fundamental frequency component when it is present in successively wider frequency bands, the frequency intervals between which are equal or less than an octave. Control signals generated in response to the presence of the fundamental components in any lower frequency channel inhibit each of the higher frequency channels thereby reducing the possibility of an overtone being detected as a fundamental frequency component of the complex wave.

Abstract: In an electronic musical instrument, a tone property setting device is provided in association with a musical tone forming circuit. The device delivers analog signals designating properties of the musical tone signals to be produced, which analog signals are converted into time division multiplexed digital signals, then processed through memories, converted back into analog signals, and are applied to the musical tone forming circuit, thereby to determine the tone properties. Digital processing utilizing the memory facilitates a variety of control.

Abstract: A buzz wave comprising n harmonic components having a flat spectrum envelope is generated according to a relatively simple algebraic expression which can be digitally computed by an arithmetic operation. Modifying harmonic components corresponding to the harmonic components to be emphasized or suppressed are also generated. The buzz wave and the modifying components are added or subtracted to form a desired musical tone signal.

Abstract: An electronic organ having a scanned keyboard manual (10) includes a keyboard latch (24) interposed between the scanning apparatus (12) and the organ keyers (26). The keyboard latch (24) comprises a gate (42) for comparing the serial data pulses, each of which represents a respective depressed key, produced at the output of the scanning apparatus (12) during each scan of the keyboard manual (10) with the serial data pulses produced during the immediately preceding scan for developing a control signal representing the detection of a depressed keyboard key during the on-going scan which was not depressed during the immediately preceding scan. An output circuit (52, 54, 56) is provided for continuously developing an output signal reflecting the keys depressed during the last scan in which a control signal was developed whereby the tone signals corresponding thereto are continuously sounded even though the keys have subsequently been released.

Abstract: Apparatus for producing a chorale or vocal effect in an electronic musical instrument comprises means responsive to the playing keys of the instrument for producing an indexing signal and means responsive to the indexing signal for sequentially developing a plurality of control signals. A programmable filter is responsive to each sequentially developed control signal for modifying the harmonic content of a tone signal to simulate a different vowel-like sound for producing a vocal effect consisting of a sequence of different vowel-like sounds as the keys are played. The modified tone signal may be coupled through a chorus generator to simulate a chorale effect and the programmed characteristics of the filter may be modulated to further animate the performance as well as being made responsive to a glide signal for producing two different vowel-like sounds in succession at two different pitches in response to a glissando or portamento command.

Abstract: Chorus effect for an original audio signal is developed by forming a complementary pair of signals from the original. The original signal is stored at a write rate (f.sub.c), then, after a delay, strobed to a pair of FIFO registers, one strobe at a higher rate (f.sub.c +.DELTA.f), the other strobe at a lower rate (f.sub.c -.DELTA.f), respectively. The faster readout will decrease the delay (to zero, causing foldover glitch), the slower readout will increase the delay (to excess delay, causing discrete echo). The strobe frequencies are reversed between FIFO registers whenever the delay becomes too great or too small.

Abstract: A system for use in electronic organs and electronically actuated organs wherein a pattern of notes sounding as if played on the accompaniment or solo manual are played from the pedalboard. The pedalboard is encoded such that depression of a pedal will generate an encoded binary word corresponding to a chord having as its root the note corresponding to the depressed pedal. Individual notes of the chord are played in a rhythmic sequence at a rate determined by the rhythm generator of the organ and in a pattern which can be selected by the organist. As the pattern is being automatically played, the organist is free to manually play a melody on the solo manual and accompaniment chords on the accompaniment manual. The pattern is changed from a major key to a minor key having the same root note by actuating a knee paddle.

Abstract: A new, performer played, real time, multitonal, multitimbral musical instrument consists of speed and force sensitive keys in which time domain multiplexing is used to find and associate one and only one tone generator, not otherwise busy, with any key that is depressed. The sound generator disclosed can provide very realistic simulations of the flute, oboe, trumpet, French horn, trombone through the provision of various types of modulations in amplitude and frequency of the various partials, as is characteristic of each instrument simulated, and filtered noise. Glissandi are provided from one note to another and are controlled from the pair of keys involved by the relative pressure with which they are depressed. For the nonpercussive tonalities, the speed with which a key is depressed, which is determined by differentiating the force, may be used to cause the attack transient to behave in a manner very characteristic of the instrument being simulated.

Abstract: An electronic piano includes a tone generator having a pulse generator and a discrete TOS circuit for each octave. The input of the first TOS circuit is connected with the pulse generator and the input of each next-following TOS circuit is connected with the input of the preceding TOS circuit by a divide-by-two divider circuit. The outputs of each TOS circuit are connected with discrete control circuits each having an analog switch for each output of the respective TOS circuit. First inputs of the analog switches receive envelope control voltage signals on depression of the respective piano keys while second inputs of the analog switches receive tone signals from the corresponding outputs of the respective TOS circuits. The outputs of the analog switches transmit tone signals, which are modulated as a function of the intensity the corresponding envelope control voltage signals, to a loudspeaker by way of either one of two main branches of the respective control circuits.

Abstract: A tone generator for electronic musical instruments, useful in particular for the modular composition of an electronic organ, comprising a plurality of inputs corresponding to a keyboard octave of the musical instrument. The inputs are connected to a plurality of groups of analog modulators which receive, respectively, tone signals produced by a tone generator and submultiples thereof produced by a plurality of toggles according to the number of footages desired on the output of the groups of modulators. The tone generator includes an audio frequency modulator having a high modulation index with full modulation depth remaining substantially constant over the whole supply voltage range.

Abstract: A tone generator system for electronic musical instruments includes a voltage-regulated, high-frequency oscillator. The output of the oscillator is connected with the inputs of first and second 12-tone divider circuits having outputs for transmission of full octaves of tone signals. The connection between the output of the oscillator and the input of one of the divider circuits contains circuitry which intercepts each n.sup.th signal of the series of signals transmitted by the oscillator so that the one divider circuit is out of tune with the other divider circuit. The number n can be varied by a battery of switches and can be as low as 2 or higher than 128. An auxiliary signal dividing circuit can be connected between the output of the oscillator and the input of the other divider circuit.

Abstract: A guitar synthesizer comprises a guitar portion and a synthesizer portion which are electrically connected to each other. The guitar portion includes strings stretched between a nut and a bridge and pickup means for detecting a string vibration for providing a guitar sound signal. The guitar sound signal is applied to the synthesizer portion. The synthesizer portion comprises a voltage controlled variable bandpass filter exhibiting a passband characteristic variable in at least two frequency regions of the guitar sound signal as a function of a control voltage. A frequency/voltage converter provides a control voltage representing the frequency of the output of the filter, to the variable bandpass filter, whereby the passband characteristic thereof is made adaptively and dominantly responsive to the frequency of the fundamental wave component included in the guitar sound signal and the fundamental wave component is extracted with accuracy from the guitar sound signal.

Abstract: An electronic musical instrument comprises a musical tone production circuit responsive to a depressed key among a plurality of keys, and a control circuit for controlling tone production manner which includes a plurality of manually operated members mounted on a control panel for setting parameters that determine the tone production manner. There is also provided presetting means for presetting some of the parameters. At an initial state after the instrument is powered from a power source, the preset parameters dominate the corresponding ones of the manually set parameters, while the preset parameters can be replaced by the manually set parameters at a choice of a player after powering.

Abstract: An electronic musical instrument comprises a sound generator connected to a loudspeaker by way of several parallel channels including respective delay lines constituted by charge-transfer devices of the bucket-brigade type stepped by different high-frequency pulse generators. Each pulse generator comprises a voltage-controlled oscillator whose output frequency is varied by a composite periodic signal obtained from a respective stage of a chain of operational amplifiers each provided, except possibly for the first stage, with an RC network acting as a frequency-dependent phase shifter for a nonsinusoidal modulating signal consisting of at least two sub-audio-frequency components. The modulating signal may be synthesized from a plurality of stepped waveforms generated by the concurrent readout, at different sampling rates, of a set of amplitude values stored in a read-only memory.

Abstract: A keyboard operated electronic musical instrument with polyphonic portamento and glissando effects in which each key controls one of a number of tone generators through a table of frequency numbers. The frequency transitions are achieved by subtracting the frequency number of a new note from the frequency number controlling the current frequency of an assigned tone generator. A predetermined fraction of the difference is stored in increment registers and added successively to the frequency numbers of the current notes until these numbers are equal to the frequency number of the new note. The addition rate, which determines the frequency transition time, is adjustable by means of a variable frequency time clock. The assignment of the tone generators to the actuated keyswitches is accomplished in a manner which prevents objectionable frequency cross-over transitions even when the number of notes in successive chords is changed.

Abstract: A sequence of timing signals is generated having a time spacing corresponding to the average spacing between successive actuations of a control switch. The system automatically starts a new calculation if the control switch is actuated at least two times with a time spacing less than some prespecified threshold time. The data input process is self-terminated when a time interval equal to the threshold time expires after an actuation of the control switch. The generated sequence of timing signals can be used as the metronome clock for an automatic rhythm generator.

Abstract: An ensemble effect is produced in a digital tone generator by providing a master data set of words having values corresponding to the relative amplitudes of equally spaced points along one cycle of a waveform of a musical tone in which the fundamental frequency is deleted. These values are read sequentially and repetitively from a memory to produce a first analog tone. A second analog tone is produced by multiplying a data set corresponding to the fundamental frequency by a low frequency sinusoid. The first and second analog tones are summed to yield a musical tone having an ensemble effect.

Abstract: A player piano recording system has photosensor flags secured to the undersides of the piano keys, vertical movement of which is detected by horizontally adjustable photosensors to produce "key played" and key velocity signals which supplied to a microprocessor for deriving expression signals for recording on magnetic tape. The microprocessor provides output expression values and key play information. According to the invention, the expression values are a direct function of key velocity and key play information and switch selected boost (an enhanced initial frame expression for overcoming solenoid inertia) and add (for trill) values. Key play data is dependent upon key play inputs and the frame extension switch value. The unique structure of the key flag permits horizontal adjustment of the photosensors for vertical misalignments etc. of the piano keys.