JPH0736110B2 - Chorus effect device for electronic musical instruments - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chorus effect device for an electronic musical instrument. 2. Description of the Related Art Conventionally, as an ensemble effect device, as shown in FIG. 1, a tone color filter 2 is interposed in a tone signal pass circuit 1 and its output terminal is provided with a plurality of delay circuits 3-1 ... 3-3, and these output terminals are respectively connected to the low-pass filters 4-1 ... 4-3 and the amplifiers 5-1 ... 5-3.
6-3 via speakers, and the delay circuits 3-1 ... 3-3 are connected to the switching oscillators 7-1 ... 7-3.
Controlled by. Reference numeral 8 denotes a low frequency oscillator, the output terminal of which is connected to each of the switching oscillators 7-1 ...
It is known that the -1 ... 7-3 generates periodically ensemble effects by giving periodic delay changes to the delay circuits 3-1 ... JP-B-52-38888). In this case, the ensemble effect of strings, brass, etc. is relatively excellent, but it is difficult to obtain a chorus effect sound by a human voice. An object of the present invention is to obtain a chorus sound effect that is similar to a human voice. According to the present invention, a tone signal from a tone signal generating means which is generated in response to a key operation is input to a plurality of variable delay means, and the variable delay means is controlled by a delay control signal. Change control signal generating means for controlling by a plurality of delay control signals generated by the generating means and generating a change control signal in response to a change in key operation, and the change control signal for the tone signal generating means or the delay control signal. In the electronic musical instrument for generating a musical tone from the output signal of the variable delay means, the musical tone signal generating means comprises a modulating means connected to the generating means for modulating a musical tone signal, and a formant filter means for adding a formant to the musical tone signal. The waveform of the musical tone signal generated in 1. contains many harmonics, and the formant filter means has at least 800 Hz and 1200 H.
It is characterized in that band-pass filters each having a resonance point near z and 2600 Hz are connected in parallel. Embodiments of the present invention will now be described with reference to the attached drawings. In FIG. 2, 10 is a main oscillator 11 and a frequency divider group 1.
2, a plurality of output terminals are connected in common through the key switch 13, and the common output terminal 14 is connected to the formant filter 15. The output terminal has a plurality of delay circuits 16-1 ... 16-3.
16-3 are connected to the low-pass filters 17-1 ... 17-3 and the amplifier 18 respectively.
18-3 was connected to the speakers 19-1 ... 19-3 via -1 ... 18-3. Reference numeral 20 denotes a keying signal generating circuit arranged in parallel with the key switch 13, the output terminal of which is connected to the vocalization initial change control signal generator 21 and the output terminal of which is connected to the control pole of the main oscillator 11. The delay circuit 16-1 ...
16-3 is BBD (BUCKET BRIGAD
E DEVICE) or CCD (CHARGECOUP)
LED DEVICE) was used. 22-1 ... 22-3
Indicates a delay control signal generator composed of a voltage control type clock pulse oscillator, and these output terminals have respective delay circuits 16
-1 ... 16-3 was connected to the control electrode. Reference numeral 23 denotes a low frequency oscillator, the output terminal of which is connected to the phase shift circuit 24, and the plurality of output terminals 24-1 thereof are provided.
24-3 are respectively the delay control signal generators 22-1 ... 2
It connects to the control pole of 2-3, and each output terminal 24-1 ... 24-
22-3 are controlled by the low-frequency signals having different phases by 120 degrees, and the delay circuits 16-1 ... 16-3 are controlled by clock pulses whose oscillation frequencies are controlled. The delay control of 16-3 is performed. The main oscillator 11 is a sawtooth wave oscillator, the frequency divider of the frequency divider group 12 is a sawtooth wave divider, and the sawtooth wave does not include the nth harmonic as shown in FIG. Are known. On the other hand, when the human voice A is analyzed, the relative levels of the overtone spectrum are 800 Hz, 1200 Hz, and 2600 H.
It was known to be high near z and 3200 Hz. Thus, the formant filter 15
15-4 are connected in parallel and the resonance points of the filters 15-1 ... 15-4 are set to 800 Hz, 1200 Hz, 2600 Hz and 3200 Hz, respectively. Fig. 4 shows one example of each,
Each of the resistors 15a-1 ... 1 is composed of a P amplifier.
The resonance frequency is determined by adjusting 5a-4. The overall characteristics are shown in FIG. Thus, the tone signal generated by operating the key, that is, the sawtooth wave, passes through the formant filter 15 and each delay circuit 16-1 ... 16-.
17 through the low pass filters 17-1 ... 17-3 and the amplifiers 18-1 ... 18-3.
By sounding 9-3, a chorus effect sound that is relatively similar to a sound can be obtained. However, since the initial pronunciation is different from that of human voice, the chorus sound is somewhat unnatural. At the beginning of the vocalization of a human voice, vocalization starts from a pitch that is relatively deviated from the planned pitch, and while listening to this, an action of approaching the planned pitch is performed. The voicing initial change control signal generating circuit 21 has this function. The first embodiment is constructed as shown in FIG. 6 to obtain the control signal as shown in FIG. That is, when the keying signal k is input, it is differentiated by the differentiating circuit 25, and the pulse P2 at the preceding stage is inverted by the transistor 26 to become the pulse P1. And NAN
The output of the D circuit 27 is "1" (OV), and the NAND circuit 28
Output becomes "0" (-15V), and the potential at the point M of the capacitor 30 sharply drops to -15v due to conduction of the diode 29, which shows a change from A1 to A2 in the steady state in FIG. Next, as the pulse P2 disappears, the NAND circuit 2
The output "1" (OV) of 7 causes the capacitor 30 to have
1 to the vicinity of OV through the diode 32 and A3 in FIG.
It is charged as shown in. Then, when the potential at the point M reaches near OV, the input voltage of the NAND circuit 33 [action of the inverter] reaches the threshold level, and its output is "0" (-
15V), and the output of the NAND circuit 27 is “0”,
The output of the NAND circuit 28 becomes "1". Therefore, the transistor 34 becomes conductive, and the capacitor 30 is discharged to a potential determined by the variable resistor 35 as shown by A4 in FIG. The changes in A1 ... A4 and A5 at the points M are taken out to the output terminal 36 via the transistor 36 and added to the control pole of the main oscillator 11. Thus, the oscillation frequency of the main oscillator 11 drops relatively greatly from the steady oscillation frequency at the moment when the key is pressed, and then approaches the steady state according to the curve portion A3, and then it is inverted and overturned, and according to the curve portion A4. The steady state is approached again and the steady state A1 is reached.
Will settle in. This frequency change is similar to the above-mentioned self-sounding being adjusted to a predetermined pitch by listening to oneself, and a chorus effect sound extremely similar to a human voice is obtained. The above is a formula in which the oscillation frequency of the main oscillator 11 is divided, but as shown in FIG. 8, the oscillation frequency is controlled by the change of the output voltage of the key switch circuit 37. The same applies to a so-called synthesizer using a. The oscillator 11 'is the sawtooth oscillator. The vocalization initial change control circuit 21
The output terminal of is connected to the control poles of the delay control signal generators 22-1 ... 22-3 as shown by dotted lines in FIGS. 2 and 8 instead of being connected to the oscillators 11 and 11 '. The initial change of vocalization is obtained in the same manner as in. Further, although the formant filter 15 has been described as having four filters 15-1 to 15-4 in the above description, even if the fourth filter 15-4 is omitted, the timbre changes greatly. Can't be seen. The case where the sawtooth wave is used has been described above. Instead of the sawtooth wave, a duty factor of 10: 1 to 1
A 0: 4 pulse wave can be used. In this case, as shown in FIG. 9, the main oscillator 11 is a rectangular wave oscillator, and its output is divided by frequency dividers 12-1, 12-2, ... And The frequency dividers 12-1, 12-2, ...
The duty factor changing circuit 4 is connected to the circuit connected to 3 ...
0, 40 ... Intervenes each. As shown in FIG. 10, the changing circuit 40 comprises, for example, a differentiating circuit 40a and a transistor 40b, and a differential pulse a1 generated by the rising edge of the rectangular wave a is applied to the base of the transistor 40b to output the output terminal 40c. A pulse wave a2 corresponding to the differential pulse a1 is obtained. The width of the pulse wave a2 is set by the capacitance of the capacitor of the differentiating circuit 40a and the value of the resistor R. The pulse wave with a duty factor of 10: 1 thus obtained has a harmonic structure shown in FIG.
As shown in 1. Also, due difighter 10:
When the fundamental frequency of the pulse wave of No. 4 is 250 Hz, its overtone structure is as shown in FIG. That is, in the former case, the period is T, τ is the pulse width,
Let f be the frequency Next, 2500Hz, 5000Hz, 7500Hz ...
Causes dip. In the latter, Therefore, dips can be made at 625 Hz, 1250 Hz, 1875 Hz .... In the former case, the level is a little low at 2600 Hz, but a sound very similar to the A sound is obtained depending on the case of the sawtooth wave, and in the latter case, 1200 Hz.
Although the level at is low, a sound very similar to A is obtained as in the former case. And a duty factor of 10: 1
The same result was obtained for each pulse wave within the range of 10: 4. Similar results were obtained for other fundamental frequencies of 200 to 1200 Hz. It is not clear why this pulse wave is more like an a-tone than a sawtooth wave, but comparing FIG. 3 with FIG. 11 and FIG. 12 shows that the one in FIG. It is thought that the cause is that the lower overtone acts more strongly due to.
The duty factor changing circuit 40 can also be used as a gate circuit instead of the key switch 13.
That is, as shown in FIG. 13, when the key switch 13 'is interposed in the circuit connecting the collector of the transistor 40b to the power source E, the transistor 40b is opened and closed by the cooperation of the differential pulse a1 and the key switch 13'. The pulse wave a2 is obtained in the same manner as in the above case. FIG. 14 shows a vocalization initial change control signal generation circuit 2
In another embodiment of the present invention, the generating circuit 21 includes a vibrato oscillator 50 so that when the keying signal is input to the input terminal 51, the vibrato signal is bleeding. That is, the vibrato oscillator 50 includes an astable multivibrator 52 and an integrating circuit 5 connected to its output terminal.
3, the output terminal 54 of the integrating circuit 53 is connected to the control pole of the main oscillator 11, although not shown. A capacitor 56 and a transistor 57 are interposed between the astable multivibrator 52 between the power supply connection circuit 55 and the ground, and the output terminal of the keying signal generator 20 is connected to the transistor 5 through a differentiation circuit 58 and a diode 59.
It was connected to the base of 7. Thus, when the keying signal is generated, the differentiated positive pulse b is applied to the transistor 57, which is conducted to discharge the capacitor 56 and set the potential of the power source of the astable multivibrator 52 to zero. Therefore, the oscillation of the unstable multivibrator 52 is stopped. Next, when the transistor 57 becomes non-conductive again, the capacitor 56 is gradually charged, oscillation is gradually started, and a vibrato signal with a droop is obtained at the output terminal 54 as shown by the solid line in FIG. Furthermore, in order to increase this weeping, for example, the output terminal 52 of the astable multivibrator 52 is used.
A resistor 59 and a capacitor 60 are connected in series between a and the power supply circuit 55a as shown by the dotted line. In this case, during normal oscillation, since the capacitor 60 is charged, there is no difference from the steady state shown by the solid line in FIG. 15, but when the transistor 57 is conducting, the output terminal 54 of the output terminal 54 passes through the resistor 59 and the capacitor 60. Since the voltage greatly drops and both capacitors 56 and 60 are charged next, the change is as shown by the dotted line in FIG. Thus, a large weeping occurs in the vibrato, and a sufficiently large initial change of development is added. The low frequency oscillator 23 for controlling the delay circuits 16-1 ... 16-3 is composed of two oscillators 23a and 23b as shown by a dotted line in FIG.
z, on the other hand, 23b oscillates at 5 Hz. Both output terminals are commonly connected, and both frequencies are superimposed and added to the phase shift circuit 24 (known means). Then, the phase shift circuit 24 delays the fundamental wave by 120 degrees and is added to each of the delay circuits 16-1 ... 16-3 described above.
This low frequency gives a complex delay change to the musical tone signal due to a large delay time change in the fundamental wave and a small delay time change in the superimposed waveform, thereby further increasing the chorus effect. The phase shift circuit 24 is configured as shown in FIG. 16, for example. That is, a constant gain phase shift circuit 62 having a delay of τ / 2 radian phase and a constant gain circuit 63 having a delay of τ / 6 radian phase are connected to the input terminal 61, and the output terminal of the constant gain phase circuit 63 is a phase inverting circuit 64. Connect to
The output terminal of the inverting circuit 64 and the constant gain phase circuit 62
And the output terminal of the inverter are connected to the adding circuit 65, and the output terminal thereof is connected to the inverting circuit 66. Thus, the constant gain phase circuit 6
2, the output terminals A, B and C of the inverting circuits 64 and 66 are shown in FIG.
As shown by the vector ABC, low frequency signals having different phases by 120 degrees are obtained. The constant gain phase circuits 62 and 63 and the inverting circuits 64 and 66 are configured by using OP amplifiers. According to the present invention, there is an effect that a chorus effect sound similar to a human voice can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a conventional device. FIG. 2 is a block diagram of an embodiment of the present invention. FIG. 3 is a harmonic structure diagram of a sawtooth wave. FIG. 4 is an example of a formant filter. FIG. 5 is a specific circuit diagram of the vocalization initial change control signal vocalization circuit. FIG. 7 is a resonance characteristic diagram thereof. FIG. 7 is an output characteristic diagram thereof. Block diagram [FIG. 9] Block diagram of yet another embodiment [FIG. 10] Concrete circuit diagram of the duty factor changing circuit 40 [FIG. 11] Overtone structure diagram of pulse wave [FIG. 12] Overtone structure diagram of pulse wave [FIG. FIG. 13 is a circuit diagram when the duty factor changing circuit 40 is configured as a gate circuit. FIG. 14 is another specific circuit diagram of the vocalization initial change control signal generating circuit. FIG. 15 is an output characteristic diagram thereof. Specific circuit diagram of the phase circuit [Fig. 17] 16 [Description of symbols] 10 tone signal generator 15 formant filter 16-1 ... 16-3 delay circuit 20 keying signal generation circuit 21 vocalization initial change control signal generator 22-1 ... 22-3 delay control signal generator 50 Low frequency oscillator

Claims (1)

[Claims] 1. The tone signal from the tone signal generating means generated according to the operation of the key is input to the plurality of variable delay means, and the variable delay means is controlled by the plurality of delay control signals generated by the delay control signal generating means. Change control signal generating means for generating a change control signal in response to a change in operation; modulation means for connecting the change control signal to the musical tone signal generating means or the delay control signal generating means to modulate a musical tone signal; In an electronic musical instrument which comprises a formant filter means for adding a formant to a musical tone signal and generates a musical tone from an output signal of the variable delay means, the waveform of the musical tone signal generated by the musical tone signal generating means includes many harmonics. And said formant filter means is at least 80
A chorus effect device in an electronic musical instrument, characterized in that band-pass filters each having a resonance point near 0 Hz, 1200 Hz, and 2600 Hz are connected in parallel. 2. The chorus effect device for an electronic musical instrument according to claim 1, wherein the musical tone signal generated from the musical tone signal generating means is a sawtooth wave. 3. The chorus effect device for an electronic musical instrument according to claim 1, wherein the tone signal generated from the tone signal generating means is changed to a pulse wave having a duty factor of 10: 1 to 10: 4.