Abstract: A double buffer system of a small storage capacity is employed for reducing the noise generation in musical waveforms. The operations of the buffers are utilized for performing an interpolation between waveforms and between successive sample points of each waveform, whereby the number of sample points of the waveform being read out is increased to smooth its level variation, producing a good quality musical tone as if it were obtained by quantizing the synthesized musical waveform.

Abstract: In the production of a desired musical waveform by combining harmonic components corresponding to respective harmonic orders, the cut-off harmonic order q.sub.c, each harmonic component value is controlled by selecting the level Ha and the slope of the Formant filter characteristic. The cut-off harmonic order q.sub.c, the level Ha and the slope value can each be varied over a predetermined range. These operations can be performed with a simple circuit arrangement involving a small number of memories. Therefore, the present invention greatly contributes to the reduction of the size and the cost of electronic musical instruments.

Abstract: An electronic musical instrument is provided with a temporal variation circuit of SCF parameters for temporally varying the filter characteristic of a switched capacitor filter circuit, a control circuit for digitally controlling the temporal variation circuit and a touch response circuit for detecting, by scanning, touch response data in performance, whereby temporal variations of a musical waveform signal are digitally controlled.

Abstract: In an electronic musical instrument which generates a musical waveform by calculating the waveform amplitude value at each sample point through Fourier synthesis, temporal variations of the musical waveform and its timbre variations in accordance with a touch response are controlled with respect to readout addresses for reading out a set of harmonic coefficient data for the Fourier synthesis from a memory having stored therein a plurality of sets of such harmonic coefficient data, thereby changing the component ratio of a harmonic coefficient which will ultimately be used as a Fourier coefficient.

Abstract: In an electronic musical instrument which generates a musical waveform by calculating the waveform amplitude value at each sample point through Fourier synthesis, note-range variations of the musical waveform and its timbre variations in accordance with a touch response are controlled with respect to readout addresses for reading out a set of harmonic coefficient data for the Fourier synthesis from a memory having stored therein a plurality of sets of such harmonic coefficient data, thereby changing the component ratio of a harmonic coefficient which will ultimately be used as a Fourier coefficient.

Abstract: In an electronic musical instrument, note frequency data corresponding to a plurality of temperaments are prestored and are selectively read out in accordance with a selected one of the temperaments, generating a note frequency corresponding thereto. Further, a plurality of note frequency data corresponding to each transposition operation for each temperament and selectively read out in accordance with a selected temperament and the transposition operation, thereby generating a note frequency corresponding thereto. Thus the temperament selection and the transposition operation can be performed with satisfactory stability and high frequency accuracy.

Abstract: In an electronic musical instrument which generates a musical waveform by calculating the waveform amplitude value at each sample point through Fourier synthesis, there is provided a musical waveform generator for caculating and synthesizing a temporally varying musical waveform at a plurality of sample points, memory circuits for storing two kinds of musical waveforms obtained by the musical waveform generator one after the other and an interpolation circuit for interpolating the two musical waveforms at time intervals shorter than the time intervals used in the musical waveform generator.

Abstract: In the generation of an envelope waveshape of a musical note to be produced in response to a key depression, speed parameters of the envelope which are determined corresponding to the speed of its attack, decay and release are produced digitally. The envelope waveshape is obtained by calculations based on the speed parameters. The formation of the envelope waveshape of the musical note, its volume level control and its tone control can be achieved with simple arrangements.

Abstract: An electronic musical instrument which is provided with a note frequency data memory for storing note frequency data corresponding to data of key switch depression through a key code register, a note frequency data register for latching and storing the data from the note frequency data memory by a time division pulse from a time division control signal generator, an octave data register for latching and storing octave data from the key code register by the time division pulse from the time division control signal generator, a frequency generator composed of a programmable counter supplied with the output from the note frequency data register to provide a frequency corresponding thereto, a frequency divider array supplied with the frequency and a decoder supplied with the output from the octave data register, the outputs from the respective output ends of the frequency divider array being selected by the output from the decoder in accordance with the octave data, and a musical waveform generator composed of fi

Abstract: A key assignor for electronic musical instruments which has a keyboard multiplexer including a memory for temporarily storing the state of key depression on a keyboard, a key priority circuit group operating to output only key information of top priority while inhibiting the other key information outputs in accordance with priority of keys of the keyboard and to output key information of the next priority after being reset, and a multiplex code generator for generating the key code corresponding to the key being depressed, a channel assignor for giving priority to channels to assign thereto the key code from the keyboard multiplexer, and a key code memory for storing the key code from the keyboard multiplexer based on a channel assign signal generated from the channel assignor.

Abstract: An electronic musical instrument which has a key assignor or assignors of one or more channels for generating and temporarily storing key code corresponding to key depression and release, respectively, a memory for storing waveshape information such as inclination and amplitude variations of a required musical waveshape divided into a plurality of periods so as to read out the waveshape information corresponding to the key code, a plurality of tone source devices, each including waveshape generators of different sound ranges respectively corresponding to keyboard switches in the same channel of each key assignor, the tone source device reading out the waveshape information from the memory on a time divided basis to generate from the waveshape generators waveshapes of different frequencies based on the read out waveshape information, and means for simultaneously actuating the corresponding waveshape generators by the key code from the key assignor and coupler information.

Abstract: A tone source apparatus for an electronic musical instrument is characterized in that at least one cycle of a musical-tone waveform, which it is desired be produced, is depicted as a sequence of section lines and a series of pulses having regular intervals is varied, by a pulse-density varying circuit, in pulse density in accordance with the degrees of inclination of the respective section lines. The resultant series of pulses having varied pulse density is formed, by a waveform forming circuit, into the desired musical tone waveform. The pulse-density varying circuit comprises a first counter to which is applied as an input, the aforementioned series of pulses having regular intervals. A second counter is connected, in series or in parallel, to the first counter and a decoder is connected to an output terminal of the second counter. A memory circuit is connected to the output terminals of the decoder.

Abstract: A tone source apparatus is provided for an electronic musical instrument. It comprises a memory circuit which has a plurality of addresses and is so arranged that where at least one cycle of a musical tone waveform is divided into p units and a waveform in each section range is represented by a formula containing the abscissa as its variable, a coefficient and a section range quantum number of each formula is memorized in the form of digital signals in the corresponding address. Also included are a clock pulse oscillator, a counter means for counting output clock pulses of the clock pulse oscillator, and a coincidence circuit serving to generate the coincidence signal when the output digital signal of the counter means and a digital signal of the section range quantum number memorized in the memory circuit coincide with one another. A decoder designates the next stage address in order by output signals of the coincidence circuit.

Abstract: An apparatus for forming a musical-tone waveform for an electronic musical instrument characterized in that at least one cycle of a musical-tone waveform, which it is desired be produced, is divided in amplitude by dividing lines at equal intervals and sampling points on a time axis are determined from respective crossing points between the waveform and the dividing lines and the distance between the initial and the final sampling points is represented by an appropriate number of pulses so that each sampling point may be represented by a pulse number. There is further provided a memory circuit wherein each sampling point, that is, the pulse number thereof is set up in the form of a digital signal. Additionally, there is a set up in the form of a digital signal a tendency such as increase, decrease or equal at each sampling point with reference to the preceding sampling point.