JPS6337398B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound source device for an electronic musical instrument that effectively contains harmonic components using sideband waves to obtain musical tones with rich timbre.

The sound source in an electronic musical instrument is usually composed of an oscillator, and this oscillator generates a sound source signal such as a rectangular wave or a triangular wave. The components effectively form musical tones.

However, musical tones in actual natural musical instruments contain harmonic components that vary over time relative to the fundamental wave component, and there are various types depending on the order, level, and state of variation of the harmonics contained. It is said to have a characteristically rich musical tone. Therefore, it is difficult to form good musical tones only by using harmonic components contained in rectangular waves, triangular waves, etc. obtained from the above-mentioned sound source oscillators.

As a means to improve these drawbacks, the generated sound source signal is frequency-modulated with a frequency signal in another audio frequency band to generate sideband waves relative to the fundamental sound source signal, and this sideband wave increases the effect. It is being considered to incorporate harmonic components. Specifically, the sound source signal is generated by a variable frequency oscillator that is controlled in response to key operations, and the former is controlled by a frequency signal from another similarly controlled variable frequency oscillator. The frequency oscillator is controlled to frequency-modulate the sound source signal with the latter frequency signal.

However, even with this method, the frequency of the sound source signal is modulated by the same frequency signal from its rise to its decay, so the level ratio of the sideband waves constituting the contained harmonic components is not uniform. be. That is, musical tones with the same timbre from the rise to the decay of the musical tones are set, and it is not possible to express the performance musical tones that can be obtained with a natural musical instrument.

This invention was made in view of the above-mentioned points. When forming the timbre of a musical tone by frequency modulating a musical tone signal, the harmonic components contained in the musical tone are effectively reduced over time. It is an object of the present invention to provide a sound source device for an electronic musical instrument that is change-controlled so that the state of expression of timbre from the rise of a musical tone to its decay is natural and rich in musicality.

That is, the sound source device according to the present invention generates first and second signals in an analog state, for example, in response to a key operation, and converts the second analog signal into an analog envelope. The signal is amplitude modulated, and the first analog state signal is frequency modulated by the amplitude modulated signal to produce a musical tone signal.

Further, when a frequency signal is generated instead of the analog signal, the frequency modulated signal is used to form a tone using a filter.

An embodiment of the present invention will be described below with reference to the drawings. Figure 1 shows its configuration.
Reference numeral 11 denotes a keyboard device, which generates a pitch signal KV having a voltage value corresponding to the pitch of the operated key and a keying signal KON corresponding to key presses and key releases in accordance with key operations. The pitch signal KV obtained from the keyboard device 11 is supplied via the adder circuit 12 to a first voltage-controlled variable frequency oscillator 13 (hereinafter abbreviated as VCO), which generates a frequency corresponding to the pitch of the operated key. Oscillates the sound source signal. Further, the pitch signal KV is further supplied to a level adjuster 15 using a variable resistor via an amplifier 14, and is converted and output as a voltage signal KV' corresponding to the operating key pitch, or the pitch signal KV It outputs the same thing as and supplies it to the second VCO 16. Then, this second VCO 16 changes according to the pitch of the operation key,
A frequency signal in the audible frequency band is oscillated, and this frequency signal is passed through the voltage controlled variable gain amplifier 17.
(hereinafter abbreviated as VCA), the adder circuit 1
2 and add it to the pitch signal KV.

That is, the first VCO 13 is oscillated by a voltage signal obtained by adding the frequency signal from the second VCO 16 to the pitch signal KV, and the oscillation sound source signal has a frequency corresponding to the operating key pitch. The sound source signal is frequency modulated by the signal from the second VCO 16. Then, the sound source signal obtained from the first VCO 13 is formed into a tone by a voltage controlled variable frequency oscillator 18 (hereinafter abbreviated as VCF),
The amplitude is controlled by the VCA 19 and an output musical tone signal is obtained from the output terminal 20. This output musical tone signal is led to a speaker section (not shown) and is produced as a performance sound.

Above VCA17, VCO13, VCF18, VCA
19, envelope waveform signals from envelope generation circuits 21, 22, 23, and 24 are supplied as control signals. Each of the envelope generating circuits 21 to 24 is supplied with a keying signal from the keyboard device 11, and generates an envelope waveform signal whose level changes as the rise time elapses as the key is pressed. in this case,
The shape of the generated envelope waveform can be arbitrarily set, and a plurality of condition signals for shaping the waveform, such as a rise time constant, a rise level, a sustain level, and a decay time constant, are sent to the control circuit 25. The voltage is set by a voltage setting circuit such as a variable resistance circuit.

That is, in the electronic musical instrument configured as described above, when a key is operated on the keyboard device 11, a pitch signal corresponding to the operated key pitch KV is generated, and the pitch signal corresponding to the operated key pitch KV is basically generated in the VCO 13. A sound source signal with a pitch corresponding to the pitch is generated. Also,
A voltage signal KV' corresponding to the pitch signal KV is generated from the level adjuster 15, and controls the VCO 16.
From this VOC 16, a wave number signal slightly shifted from an integer multiple or several times of the sound source signal is generated, and this frequency signal is added to the pitch signal KV in the adding circuit 12. Therefore, the sound source signal generated by VCO 13 is VCO 1 in the audio frequency band.
It is generated in a frequency modulated state with the signal from 6.

In this case, the modulation signal for frequency modulating the sound source signal, that is, the oscillation signal from the VCO 16, is subjected to level or amplitude envelope control in the VCA 17, and the envelope waveform is set by the envelope generation circuit 21. This envelope generating circuit 21 is controlled by the keying signal KON from the keyboard device 11.
For example, a waveform signal whose level changes over time is generated, with an attack rising when a key is pressed, continuing at a sustain level thereafter, and falling and decaying when a key is released, and a frequency of a sound source signal generated from the VCO 13 corresponding to the envelope waveform. The modulation depth changes.

Here, if the sound source signal basic angular frequency corresponding to the pitch signal KV is ωc, the frequency signal angular frequency from the VCO 16 is ωs, and the sound source signal obtained by the VCO 13 is (t), then (t)=Acos{ωct+msinωst}. Become. Here, ωc and ωs are within the audible band,
nωc≒ωs (n is a natural number), therefore, by changing m (modulation degree), the spectrum of the output sound source signal (t) changes.

Therefore, the spectrum of the output sound source signal from the VCO 13, whose modulation degree m changes by the VCA 17, changes over time from the time the key is pressed, and the tone changes according to this spectrum change. However, it is possible to obtain musical tones that are extremely natural and whose timbre is controlled.

The frequency components constituting the spectrum described above, that is, the overtone components with respect to the fundamental wave of the musical tone signal, are determined by the frequency signal angular frequency ωs from the VCO 16. For example, if the frequency signal angular frequency ωs from the VCO 16 is selected by the level adjuster 15 to be an exact integral multiple of the fundamental angular frequency ωc, a harmonic tone will be obtained, and if ωs is selected to be slightly deviated from the integral multiple of ωc, a harmonic tone will be obtained. A harmonious sound can be obtained.

FIG. 2 shows another embodiment of this invention,
The sound source signal generated by the VCO 13 is converted into, for example, a sine wave, square wave, or sawtooth wave signal by a waveform conversion circuit 26, and one of the square wave and sawtooth wave signals is selected by a switch 27 and the level is adjusted. and VCF
18 forms the tone. Then, the output signal from the VCF 18 and the sine wave signal are appropriately mixed and output.

Further, the output frequency signal from the VCO 16 is also subjected to waveform conversion by the waveform conversion circuit 28, and its sine wave component is supplied to the VCA 29. This VCA 29 controls the pitch signal KV from the keyboard device 11 with a voltage signal KV' amplified to an integral multiple or close to an integral multiple, sets the frequency signal to a level corresponding to the pitch, and
The degree of frequency modulation of the output sound source signal is changed to correspond to the pitch, so that it is audibly uniform over the entire sound range. In this case, the waveform of the output signal from the VCA 29 is set to a vertically asymmetrical level by the waveform conversion circuit 30, and is supplied to the VCA 17.

In other words, in the VCA29, the amplitude of the modulated wave increases as the pitch rises.As the frequency rises exponentially as the pitch rises, the amplitude of the modulated signal is adjusted accordingly, and the same modulation is performed depending on the range. It is something that can be done. In addition, the waveform conversion circuit 3
0, the vertically symmetrical modulated wave obtained from the VCA 29 is converted so that it becomes larger on the upper side and smaller on the lower side. This is due to the operating characteristics of VCO13, which causes the pitch voltage to change exponentially as the pitch increases.
The modulation wave is also set accordingly to enable the same modulation on the upper and lower sides.

Further, the square wave and sawtooth wave output signals from the waveform conversion circuit 28 are selected by a switch 32 and appropriately level controlled, and the tone is formed by the VCF 31.
It is mixed with the signal from VCO 13 and used as a musical tone signal.

In other words, according to this embodiment, two series of sound sources with different pitches are constructed, and the degree of frequency modulation in the basic sound source signal changes in accordance with the pitch, so that the sound source is very effective over the entire sound range. This allows for the formation of musical tones.

In this embodiment, the pitch voltage is changed exponentially with respect to the pitch, a linear VCO is used, and the modulation signal is corrected by the waveform conversion circuit 30. . However, the oscillation frequency changes exponentially with the input voltage.
If a VCO is used to linearly change the pitch voltage in response to changes in pitch, it is not necessarily necessary to correct the modulation signal.

As described above, according to the present invention, the first signal and the second signal are generated in accordance with the pitch of the operation key,
The second signal is amplitude-modulated by an envelope signal, and the first signal is frequency-modulated by the amplitude-modulated second signal to form a musical tone signal. Therefore, there are no problems that occur when the modulation index is changed over time, such as occurs when frequency modulating a digital signal, and unnecessary noise signals are not generated. . There is also a device that can very effectively set the state of harmonics contained in the performance sound, and the harmonic content state can be controlled to change depending on the duration of the performance sound, making it possible to easily control the generation of high-quality musical sounds. This is what happens.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating a sound source section of an electronic musical instrument according to one embodiment of the invention, and FIG. 2 is a diagram illustrating another embodiment of the invention. 11...keyboard device, 12...addition circuit, 13,
16... Voltage controlled variable frequency oscillator, 17,1
9, 29...voltage controlled variable gain amplifier, 18,
31...Voltage controlled variable filter, 21-24...
...Envelope generation circuit.

Claims (1)

[Scope of Claims] 1. A first means for generating a voltage pitch signal corresponding to the operation key pitch, a second means for generating an analog signal corresponding to the operation key pitch, and this second means for generating a voltage pitch signal corresponding to the operation key pitch. third means for amplitude modulating the analog signal generated by the means by an analog waveform signal that changes over time; and a third means for modulating the pitch signal in response to the analog signal amplitude modulated by the means. 4. A sound source device for an electronic musical instrument, comprising: the means of item 4; and means for generating a sound source signal having a frequency corresponding to the pitch signal modulated by the fourth means. 2. A first means for generating a first frequency signal of a frequency corresponding to the operating key pitch, a second means for generating a second frequency signal of a frequency corresponding to the operating key pitch; third means for amplitude modulating the generated second frequency signal by a waveform signal that changes over time; A sound source device for an electronic musical instrument, characterized in that it comprises a fourth means for frequency modulating a frequency signal, and a fifth means comprising a filter for forming a timbre of the first frequency signal frequency-modulated by the means. .