Abstract: In a keyboard operated electronic 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 audible musical waveform are transformed at an average rate corresponding to the fundamental frequency of the tone being generated, a computation means is provided whereby the number of data words is varied adaptively with the fundamental frequency. The adaptive variation in the number of data points per waveshape cycle is accompanied by an associated adaptive variation in the maximum number of harmonics for the generated musical tone.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators that are assigned to actuated keyswitches. Musical tones are produced by computing a master data set which defines the data points for a period of the musical waveshape. The computation uses a preselected set of harmonic coefficients. The time required to complete a master data set computation is reduced by dividing the set of harmonic coefficients into a number of subsets of coefficients. The harmonic coefficients are combined by a combination of a reverse addressing and complementing in a logic that decreases the required number of computation time intervals.

Abstract: A keyboard operated electronic musical instrument is disclosed wherein the number of tone generators is less than the number of keyswitches in a keyboard array of keyswitches. If all the available tone generators have been assigned to actuated keyswitches, the actuation of an additional keyswitch causes the oldest tone generator to be assigned to the newest keyswitch. The assignment action does not depend upon the release of any keyswitch. A phase addition means is used to remove the oldest tone generator so that release key clicks are not generated.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators that are assigned to actuated keyswitches. Musical tones are produced by computing a master data set which defines the data points for a period of the musical waveshape. The computation uses a preselected set of harmonic coefficients. Provision is made for altering the harmonic coefficients to produce waveshapes which are derivatives or integrals of the basic waveshape. The order of differentiation or integration can be varied to produce time variant tone effects.

Abstract: A musical waveshape generator is disclosed in which musical tones at mutation pitches corresponding to an actuated keyswitch are generated by selected attenuation of overtones of a square wave signal. A harmonic suppression means is described which is a combination of a low pass filter, a signal subtractor, and a rectangular waveshape generator whose state changes are controlled by a signal level comparator.

Abstract: A keyboard operated musical instrument is disclosed in which a musical tone having an extended range of harmonics is produced by combining two waveshapes. The first waveshape has a spectrum containing only the odd-numbered harmonics and the second waveshape spectrum has all the harmonics and is phase locked to the first waveshape. The second waveshape has a fundamental frequency which is twice the fundamental frequency of the first waveshape.

Abstract: A keyboard operated electronic musical instrument is disclosed in which a first set of tone generators is assigned to actuated keyswitches on a first keyboard and a second set of tone generators is nominally assigned to actuated keyswitches on a second keyboard. Assignment logic is provided so that when all the members of the first set of tone generators have been assigned an addition keyswitch actuation causes the temporary borrowing of one of the tone generators in the second set to respond to the newly actuated keyswitch. Saturation of tone generator assignment is diminished by a glissando detect subsystem which inhibits the use of a long release envelope release phase if a glissando has been initiated.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators which are assigned to actuated keyswitches. Musical tones having an anharmonic overtones structure are produced by generating a number of component waveshapes each having a different fundamental frequency. These component waveshapes are summed to produce a single tone. Each component waveshape has a spectral content of a preselected subset of non-zero harmonic coefficients. The various components have mutually exclusive selection for the non-zero harmonic coefficients.

Abstract: An electronic musical instrument of the type which synthesizes a musical waveshape from a preselected set of harmonic coefficients is disclosed in which the tonal effects of a set of intramanual couplers is produced. The desired tonal effect is obtained by selecting particular subsets of the harmonic coefficients and combining the selected subsets in response to actuated tone switches.

Abstract: A keyboard operated electronic musical instrument is disclosed in which an independent monophonic tone synthesizer is operated from the same keyboard that controls the generation of tone from a polyphonic tone generation system. The highest frequency note is assigned to the monophonic tone synthesizer and all other actuated keyboard switches are assigned to the polyphonic tone generation system. The detection of the highest note is initiated each time that a keyswitch changes from an unactuated to an actuated state. An alternative arrangement is to assign the lowest frequency note to the monophonic tone synthesizer.

Abstract: A keyboard operated electronic musical instrument in which a number of tone generators are assigned to actuated keyswitches in which a combination of a transient voice and a steady state tone is generated by implementing a discrete Fourier transform employing a selected sequence of harmonic coefficients. A harmonic sequence select logic in cooperation with signals from actuated tone switches provide the selected sequence of harmonic coefficients. A percussion coefficient is added to the sequence of harmonic coefficients in response to a percussion control signal. Various playing modes are disclosed. In one mode the transient voice is generated with the actuation of the first keyswitch on a selected keyboard, and other subsequent actuations are ignored. In a second mode, a transient voice is actuated if at the time of a keyswitch actuation no other transient voice is being generated.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators that are assigned to actuated keyswitches. Logic is provided for generating a note range signal for each preselected group of contiguous keyswitches in which the note range signal is selected for an actuated keyswitch. Musical effects such as vibrato and tone changes are selectively actuated in response to the note range signal. A mixture tone generator is described which uses a single set of harmonic coefficients which are translated and shifted in response to the note range signal.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators which are assigned to actuated keyswitches. The tone generation is produced by sequentially and repetitively accessing a memory containing a set of data points which define a period of a preselected musical waveshape. Apparatus is described whereby a plurality of tone generators are implemented such that each has an ensemble tone effect created by adding together a number of composite tones. Each tone generator is implemented by selecting a corresponding set of data points read out of the memory. The selection logic is controlled by select gates and a comparator which is responsive to the frequency of an associated actuated keyboard switch.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators that are assigned to actuated keyswitches. The tone generation is produced by sequentially and repetitively accessing a memory containing a set of data points which define a period of a preselected musical waveshape. Apparatus is described whereby a plurality of tone generators are implemented by each one selecting data points read out of the memory in response to a comparison logic.

Abstract: A keyboard operated electronic musical instrument having a number of tone generators which are assigned to actuated keyswitches. A tone selection means is implemented comprising an autocorrelation function generator. A set of harmonic coefficients is created by means of a discrete Fourier-cosine transformation of the autocorrelation function. A computing means transforms the harmonic coefficients to musical tones. The generated musical tones are varied in tone color by selecting the shape of the autocorrelation function. A means is provided to vary the autocorrelation function in a time variant manner in response to a control signal.

Abstract: An electronic musical instrument having two keyboards is disclosed in which chords detected on the accompaniment keyboard are used to vary the selected tone color of the tones played on the solo keyboard. The solo tones are synthesized by means of a Fourier transform using a set of harmonic coefficients. Selected harmonic coefficients are scaled in magnitude in response to the chord type detected from the notes played on the accompaniment keyboard.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators that are assigned to actuated keyswitches. A tone generation computation means is implemented using a combination of an even symmetric function and an odd symmetric function. One of these functions is scaled in magnitude in response to a modulation control signal. The scaled and unscaled functions are combined to produce a musical waveshape which is frequency modulated by changes in the level of the modulation control signal.

Abstract: A keyboard operated electronic musical instrument in which a number of tone generators are assigned to actuated keyswitches in which a flute chorus of similar tones at preselected pitch footages are generated by implementing a discrete Fourier transform employing a selected sequence of harmonic coefficients. Two stored harmonic coefficients suffice to generate a tibia type flute chorus. A harmonic sequence select logic in cooperation with signals derived from actuated tone switches provide the selected sequences of harmonic coefficients.

Abstract: A keyboard operated electronic musical instrument in which a number of tone generators are assigned to actuated keyswitches in which provisios are incorporated for simultaneously generating a combination of tones. Tones in the first family are generated with a maximum of Q harmonics by implementing a discrete Fourier transform employing stored sets of harmonic coefficients. Tones in the second family are obtained by operations on a frequency number and have a maximum of 2 Q harmonics. The second family of tones are generated in a manner that inherently provides ample noise reduction.

Abstract: Apparatus is described to control the starting phase of a new tone for a keyboard operated electronic musical instrument having a number of tone generators. An interval detection subsystem is used to determine if a new note is separated by a given musical interval, such as an octave, from a currently generated musical tone. If the prespecified separation is detected the new tone generator is initialized so that its starting waveshape phase is equal to that of its related interval neighbor. Provision is incorporated to shift the new tone generator by a random frequency offset to phase unlock the octave intervals.