Abstract: An electronic musical instrument is of a type in which musical tone signal waves are formed by calculation under wave forming algorithm in an algorithm circuit. The algorithm circuit has a plurality of arithmetic circuits connected by gates. Control signals are applied to the gates and the arithmetic circuits to constitute a certain algorithm performing circuit connection depending upon a selected king of tone. These control signals are sequentially produced at predetermined timing from a pitch data generation circuit, an envelope generation circuit, and an algorithm control data generation circuit.For calculation of tone waves of different tone colors, different types of algorithm performing circuits are established, thereby realizing wide variety of tone properties.

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: A programmable electronic musical synthesizer includes a memory controlling a plurality of parameter circuits according to a selected group of stored parameter signals for producing a desired timbre of sound. A memory override system is responsive to manual operation of each of a plurality of control knobs for overriding a corresponding stored parameter signal and coupling an externally derived input signal to the associated parameter circuit. The memory override system thereby conveniently enables one or more selected parameter circuits of the synthesizer to be manually controlled by a performer while the other parameter circuits are simultaneously controlled from memory.

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: A high frequency roll-off circuit for a gain stage including an amplifier having a feedback network together with a dual potentiometer comprising two serially connected gang operated resistors connected between the amplifier feedback port and through a capacitor to the amplifier output port, one of the resistors forming a volume control and the other resistor forming a high frequency roll-off control whereby at high volume settings, high frequency roll-off is automatically provided.

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: A circuit which allows for the simultaneous control of the bias voltages applied to the screen grids and control grids of output tubes while maintaining the ratio of said voltages, thereby providing a method for selectively varying a single plate characteristic (Power Output) of a tetrode/pentode vacuum tube.In the case of musical instrument amplifiers, it is a desirable effect to drive the power amplifier (output stage) beyond the point that said power amplifier is able to reproduce its input signal accurately, hence causing output distortion. Said point is known as the "Clipping Point".A clipping point is most usually achieved at high sound pressure levels which are uncomfortable and difficult to work under. By varying said voltages in the previously stated manner, one varies the clipping point accordingly, and therefore is able to obtain output distortion at variable sound pressure levels.

Abstract: An electronic musical instrument, which enables a player easily to select by operating a switch any of a plural number of tone colors from a large number of tone colors originally preset in the musical instrument in a form of tone color data stored in a memory unit, to thereby more easily carry out a performance within a broadened range of performance techniques.

Abstract: A tone synthesizer for generating a musical tone where harmonic content can be varied with time to produce unique sound effects. This is accomplished by generating waveform data in time sequence, delaying the waveform data by a time interval that is variable, and subtracting the delayed data from the waveform data to provide a modified sequence of waveform data which is then converted to an audio wave.

Abstract: The invention concerns a polyphonic musical synthesizer using digital techniques. The generation of successive wave form patterns makes use of phase data for addressing a wave form memory, and of amplitude and harmonic or octave row data contained in a set of memory blocks. Control of the synthesizer is effected by externally addressing the memory set in order to write the aforementioned data in it.The development of synthesis operations within the synthesizer is conditioned by a sequential chain of reading of the different memory blocks in terms of signals from a plurality of generators.

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: 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: 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: In a digital tone synthesizer of a type using digital data representing the amplitudes of a predetermined fixed number of sample points along one cycle of the audio waveform of a musical tone and an oscillator controlling the sampling frequency as well as the pitch of the tone, a digital filter for transferring the digital data to a digital-to-analog converter at the sampling rate. The digital filter, in response to applied input coefficient values, operates as a low pass or high pass filter in which the cut-off frequency is a predetermined harmonic of the pitch frequency of the tone. By changing the coefficient values, the cut-off harmonic can be changed for a tone independently of the pitch of the tone. Thus any tone of the musical scale may be filtered to modify the harmonic content independently of the pitch of the tone.

Abstract: A method and apparatus for producing sounds from one or more-time overlapg sequences of one or more electrical pulse signals having a frequency corresponding to the pitch of the sound to be produced from the signals holding the pulse width or pulse pause width in each sequence substantially constant for signals corresponding to a range of pitches of the sound to be produced. The pulse widths or pulse pause widths are then relatively abruptly changed over a short interval in pitch at the upper limit of the range. In this way, the shape of each pulse in a sequence and the phase between pulses in concurrent sequences which determine the timbre of the sound remains the same over the range of sounds to permit the method and apparatus to accurately duplicate the sounds of traditional musical instruments.

Abstract: An elementary digital filter comprising an arithmetic logic unit with associated registers and timing circuits, simulates a current and a voltage in a corresponding elementary analog filter. The frequency response character of this elementary digital filter is changed when a coefficient used in the simulation or the sampling period used as the data renovation cycle of the simulation is changed. A digital filter circuit is composed of such an elementary digital filter or a combination of such elementary digital filters. A time function is passed through this composed digital filter circuit, and the output of the digital filter circuit is converted to an analog voltage to produce a musical tone. The tone quality of the produced musical tone is determined by the original waveform of the time function and the frequency response character of the composed digital filter circuit.

Abstract: There are provided means for generating a digital information which varies periodically and repeatedly at a rate corresponding to the pitch of a tone to be produced, a plurality of function generators respectively supplied with the digital information for producing different linear functions, means for selecting the outputs of the function generators at a timing related to the period of the digital information and means responsive to the selected output of a function generator for generating a musical tone.

Abstract: An electronic organ tone generating technique produces a harmonic equivalent of a sawtooth wave. In one embodiment square waves generated by a conventional tone generator are applied to a one shot multivibrator, the output of which is a series of narrow rectangular pulses having a flat harmonic spectrum with both even and odd harmonics present. The narrow rectangular pulses are applied to a 3db per octave filter to produce a waveform, the harmonic content of which is equivalent to that of a sawtooth wave. In this embodiment, the pulse width remains constant regardless of the frequency of the pulse train. In a second embodiment, the duty cycle at each octave when moving up the keyboard is doubled to compensate for amplitude falloff which may occur in the filtered signal.

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: 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 output 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: In a wave shape generator of the memory reading type, a waveshape memory stores sample values of a wave each value being represented by an integral address. A coefficient memory stores coefficients for nth order interpolation. Unknown intermediate sample values not stored in the wave shape memory represented by non-integral addresses and are approximated by multiplication of stored sample values of the waveshape and corresponding coefficient values on the basis of nth order interpolation. Use of the interpolation method assures smoothness of the wave shape with respect to time and thereby minimizes quantization noise while permitting use of relatively small memories.

Abstract: In a musical instrument in which a plurality of data words corresponding to the amplitudes of a corresponding number of evenly spaced points defining a cycle of an audio waveform are transferred sequentially from a waveshape memory in repetitive cycles at a rate proportional to the pitch of the tone being generated, apparatus is provided for reducing undesired frequency components resulting from the conversion of the digital signals into analog musical signals. The noise reduction apparatus applies optimal amplitude weighting values to a subset of the stored data words and adds these weighted values together to provide a new single value which is used for the output signal.

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: This is an electronic organ drawbar circuit in which selection of the footage volumes is accomplished by means of a switch matrix; and sets of footage/volume correlations so chosen are stored in a memory. Another group of switches is used to select among several different memory fields, so that various sets of footage/volume data can be stored while another set of data is in use, and each stored set can be recalled for subsequent re-use.

Abstract: An electronic musical instrument is capable of processing, by the same processing circuit, parameter control analog information signals defining the shape of control waveforms for the modulation of musical tone signals, and analog musical tone signal generation mode select signals for selecting, for example, a musical tone signal waveform and filter characteristic. The parameter control analog information signals and generation mode analog select signals are both optionally set by a player and are multiplexed in a time sharing manner by an analog multiplexer. The multiplexed analog signals are converted into digital signals, which are converted into analog signals, and further demultiplexed. In a write mode, the digital signals are stored in a memory, while, in a read mode, the digital signals are read out of the memory, converted into analog signals, and demultiplexed.

Abstract: A digitized multifrequency tone generator comprising a memory having N readable word locations with each location containing an amplitude representing binary word, and with the total N binary words sequentially and collectively representing a period T.sub.o of the waveform of a multifrequency tone such as a chime with certain harmonics contained therein. Memory scanning signals of frequencies Nf.sub.o, where f.sub.o =f.sub.1, f.sub.2 . . . f.sub.n, are each employed, one at a time in a predetermined chime sequence, to repeatedly and sequentially read the N words from the memory to form a sequence of chimes each of whose fundamental tone frequencies is equal to the employed scanning frequency f.sub.o =f.sub.o1, f.sub.o2 . . . f.sub.n, with the said harmonics being reproduced at the proper frequency relative to each scanning frequency. A digital-to-analog device converts the read out binary words to form the aforementioned waveform.

Abstract: An electronic musical instrument of a type capable of producing a musical tone corresponding to the tone pitch of a depressed key by controlling oscillation frequency of a voltage-controlled type oscillator by a pitch voltage corresponding to the tone pitch, wherein musical tone elements such as tone pitch and tone color are controlled in accordance with a control voltage which is produced for each individual key but is different from the pitch voltage.A temperature curve can be determined by controlling the tone pitch of the musical tone by this control voltage as well as by the pitch voltage. A desired temperament curve can be obtained by suitably adjusting the values of the control voltage for the respective keys. The tone color control is effected by varying the cut-off frequency of the voltage-controlled type filter in accordance with the aforementioned control voltage.

Abstract: A brass pulse keyer for electronic instruments such as electronic organs wherein the tone during attack is both amplitude modulated and pulse width modulated. The keyer is adapted for large scale integration and comprises a timing capacitor, an electronic switch connected between a source of charging potential and a capacitor and having a control terminal which is connected to the tone input, and a second electronic switch connected in series with the charge voltage, the first switch, and the capacitor and having a control terminal connected to receive the keying envelope. A comparator compares the potential on the capacitor with a reference potential and disables a gating circuit when a compare condition is reached such that the duty cycle may be controlled. As the keying envelope continues towards its maximum, the duty cycle decreases so that a more brilliant tone is achieved.

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: 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: In a musical instrument having one or more tone generators in which a plurality of data words corresponding to the amplitudes of a corresponding number of evenly spaced reference points defining the waveform of one cycle of an audio signal are transferred sequentially from a note register to a digital-to-analog converter in repetitive cycles at a rate proportional to the pitch of the tone being generated, apparatus is provided for adaptively computing the set of data points in response to values of preselected harmonic coefficients. The computation apparatus advances past all harmonic coefficients of smaller magnitude than a selected threshold thereby reducing the computation time and making the instrument capable of responding to time varying tonal changes.

Abstract: Data-processings for spectrum signals which express the frequency spectrum distributions of corresponding tone waveshape signals, are performed on a frequency domain. The processed spectrum signals are transformed to the corresponding tone waveshape signals by the Fast Inverse Fourier Transform algorithm. Thus filters of desired characteristics on a frequency domain can be composed of simple and inexpensive circuits, and musical tones having desirable tone qualities with abundant varieties can be easily generated.

Abstract: In an electronic musical instrument of a keyboard type wherein waveshapes with different tone colors read out from waveshape memories are mixed together at a mixing ratio according to a control signal and the resultant signal is converted to a corresponding musical tone, the control signal is varied with lapse of time and also is controllable in response to the initial speed at which a key of the keyboard is depressed and to the strength of pressure of the key being depressed, in addition to time lapse. Thus, the pattern of tone variation can be variously controlled.

Abstract: In order to tune the frequency characteristics of a filter or oscillator as an exponential function of the position of a note on a musical scale, a pulse stream with an exponentially scaled duty cycle is used to gate an on-off switch which controls an electronic tuning signal for the first or second stage of the filter or oscillator. The pulse stream source can be a pulse code generator responsive to a priority note generator, or it can be an oscillator-driven one-shot with an exponentially scaled power supply governing the charging rate of a reactive component which determines the one-shot cycle time. There are also pitch offset and pitch modulation features in the circuit, the latter being usable in a constant deviation or a constant interval mode.

Abstract: A musical tone varying in tone color with the lapse of time is produced in an electronic musical instrument by retrieving a plurality of different waveshapes from a plurality of memories and then by mixing these retrieved waveshapes at a variable ratio according to a plurality of time-dependent parameters. In order to ensure a simpler arrangement of the instrument while maintaining richness in tone color variation characteristics of the produced musical tone, the mixing is adapted to be performed by carrying out multiplications individually on the respective retrieved waveshapes with the associated time-dependent parameters and then by adding up the resultant values to obtain the aimed musical tone. Some of the time-dependent parameters may be derived from other time-dependent parameter in the mixing procedure of several different waveshapes.

Abstract: In a keyboard electronic musical instrument of waveshape memory type wherein different waveshapes read out from memories are mixed together at a variable mixing ratio according to variable parameters and then converted to a musical tone, the variable parameters are calculated on the basis of information associated with both lapse of time and the pitch of a musical tone to be produced. Thus, with this musical instrument, it is possible to produce a musical tone varying in the content of higher harmonics with respect to the pitch of the tone assigned to a depressed key and in tone color according to lapse of time.

Abstract: In an electronic musical instrument wherein a frequency information related to the tone pitch of a depressed key is repeatedly accumulated and the progressing accumulated value is used to designate the addresses of a waveform memory device storing the waveform of a desired musical tone, the frequency information is varied with time instantaneously so as to vary the speed of addressing the waveform memory and thereby to vary the waveform read out from the waveform memory device, thus changing the color of the produced musical tone.

Abstract: A multiple-stage active RC distributed filter having multiple inputs and a single output for producing filtering of large groups of notes for tone coloration in electronic musical instruments. Output signals from the keying circuits may be applied to selected input stages of the filter through a resistor matrix to produce the desired tone coloration. Voicing may be further modified by one or more compensation networks at the filter output.

Abstract: The electronic musical instrument is provided with a plurality of musical tone generating channels of a number smaller than that of the keys and a channel processor for randomly assigning key information representing depressed keys to the musical tone generating channels. Furthermore the musical elements including the pitch, the tone color and the envelope of the musical tones generated by respective channels are made to be different thereby imparting a random property (casualness) to the generated musical tone.

Abstract: A special effects circuit for use in an electronic musical instrument, preferably an electronic organ, including a filter circuit having variable bandpass characteristics and a tone source supplying a signal to the input of the filter circuit. The bandpass characteristics of the filter circuit are modified in accordance with a control signal. Upon the occurrence of an input signal, a control circuit provides the filter circuit with the control signal at a random or pseudo-random value. The instrument player may select the source of input signals from a variety of sources within the organ thereby determining the times or frequency at which the control signal changes but the value of the control signal is random or pseudo-random. The tone signal output from the filter circuit has randomly or pseudo-randomly attenuated frequency characteristics and is coupled to standard organ output circuits for audio presentation.

Abstract: An electronic musical instrument is provided with a plurality of wave shape memories storing different musical tone wave shapes of different memory sizes for different tone ranges. The memory for the treble tone is of a small size and that for the bass tone is of a large large size. When a key is operated in the keyboard, a memory corresponding to the tone range to which the operated key belongs is selected and read out. While successfully avoiding economically disadvantageous increase in the memory size of the wave shape memories, beautiful and clear musical tones can be obtained having different tone colors for different tonal pitches just like those generated by natural musical instruments.

Abstract: A fixed formant filter for a digital electronic instrument of the type in which musical tones are generated from waveshape data calculated independently of frequency of the tone from constituent generalized Fourier components. The Fourier components are individually scaled by scale factors selected from a set of stored scale factors which define the transfer characteristic of the fixed formant filter. Each separately addressable stored scale factor corresponds to a different frequency value in the musical scale. A scale factor is selected for separately scaling each harmonic of the tone generated in response to the particular note of the musical scale keyed on the instrument. The selected scale factors may be modified by a frequency deviation signal to provide vibrato or other frequency modulation effects.

Abstract: A brass keyer system for an electronic organ wherein the keyboard is multiplexed to produce a polyphonic serial data stream, which is then converted to a monophonic serial data stream containing a keydown signal in a time slot corresponding to the highest note played on the keyboard. The monophonic data stream is converted to a multiple bit binary word that is used by the tone generation and keying portion of the system to produce a rectangular wave tone corresponding in frequency to the highest depressed key and having amplitude and pulse width modulation on attack and decay so as to produce a brass tone. The monophonic serial data stream is demultiplexed by means of a recirculating delay loop which repetitively recirculates the keydown pulse for the depressed key. The number of recirculations of this pulse are counted by a first counter and the position of the pulse within the delay loop is registered by a second counter, which is synchronized with the multiplexer.

Abstract: An electronic musical instrument develops digital pulses corresponding to electronic waves that are subsequently converted to audio sound such as by means of a loudspeaker. The musical instrument is provided a source of master frequency generated binary related numbers which act in conjunction with a read only memory, an adder, and a comparator, and also a counter, to control a J/K flip-flop to produce a pulse train output in which for any given cycle the starting time and duration of each pulse is controlled, thereby to determine the harmonic content of the electronic waves that are converted to audio sound.

Abstract: A keying arrangement for electronic organs in which a tone signal consisting of a square wave having, for example, a fifty percent duty cycle is connected to the input of the keyer circuit, and the output thereof, upon the depression of a playing key, consists of a pulse train with the amplitude rising at a controlled rate and the pulse width or duty cycle decreasing at a controlled rate but lagging the increase in amplitude so as to closely duplicate the playing of a muted brass instrument in the attack fashion. A muted brass tremulant affect is achieved by applying a cyclically time variant signal to modulate the pulse amplitude and pulse duty cycle, again with the change in duty cycle lagging the change in amplitude. The circuitry for accomplishing this comprises a diode keyer wherein a pair of resistor-capacitor circuits having different time constants control the keyer to effect variations in pulse amplitude and duty cycle over respective intervals of time.

Abstract: A musical sound controlling apparatus preferably incorporated into a music synthesizer type electronic music instrument and capable of generating a musical sound controlling signal in accordance with vocal signals or musical sound signals produced by musical instruments other than the music synthesizer type electronic musical instrument. The apparatus comprises a voltage-controlled filter whose frequency characteristics is controlled in accordance with a control waveform applied thereto and a control waveform generator which produces a control waveform varying with time in response to a trigger signal applied thereto. An external musical sound signal is applied to a switching circuit having a hysteresis characteristic through a rectifier circuit. The switching circuit is arranged to produce a stabilized trigger signal to be applied to the control waveform generator and have first and second different input switching levels for switching the output of the switching circuit.

Abstract: A music synthesizer is disclosed. In the preferred embodiment, it cooperates with a tone source, such as a conventional or traditional music instrument, to form a synthesized output. The output can be voiced to provide music shaped and modified to a desired form. The circuit of the present invention uses an input signal supplied to a phase lock loop circuit coupled to a Walsh function generator providing Walsh output signals at frequencies corresponding to the input fundamental tone and a cascade of harmonics of the fundamental. The signals are selectively summed and weighted to form an output.

Abstract: A fixed formant filter for a digital tone generator uses a set of scale factors generated by storing in memory a set of words corresponding to the relative amplitude of points on a single resonance curve. The words are addressed and read out of the memory in sequence in response to a counter. For each output state of the counter a group of words is read out of the memory, added, and stored as one scale factor of said set of scale factors. The number of words in the group read out corresponds to the number of resonant peaks in the fixed formant filter. The respective words in the group are addressed by modifying the output of the counter respectively by four constants corresponding to the relative position in the musical scale at which the resonant peaks of the formant filter occur.

Abstract: An electronic musical instrument having the key range divided into upper and lower divisions, including a logical circuit converting the change-over position outputs of a key range dividing position selecting switch into gate control signals specifying corresponding key range dividing positions and a plurality of gates controlled by these gate control signals, thereby controlling the distributive mode of keyed tone signals to different tone color filters.

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.