JPS587435Y2 - Electronic musical instrument effect circuit - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an effect circuit for an electronic musical instrument that controls the addition of effects in a natural manner when switching and adding modulation effects such as tremolo and chorus to performance sounds.

In an electronic musical instrument, a sound source signal extracted in response to a key operation is formed into a musical tone signal by a filter circuit or the like, and then supplied to a speaker to produce a performance sound.

If you want to add another effect, such as a tremolo effect, to the performance sound obtained in this way, it may be possible to use, for example, a rotating speaker that mechanically rotates in the sound radiation direction. There is.

If such a rotating speaker is used, a relatively good tremolo effect etc. can be expressed, but with this method, the heavy speaker must be mechanically driven to rotate, so the response is poor. Not only are there poor performance, but there are also many buttons that generate mechanical noise.

Therefore, many means are used to electronically add a tremolo effect, for example, by electrically modulating the amplitude of a musical tone signal at a tremolo period.

FIG. 1 shows an example of conventional means for adding tremolo and chorus effects, in which a sound source signal corresponding to each pitch is generated in a sound source circuit 11, and the sound source signal from this sound source circuit 11 is sent to the keyboard 12. It is selectively derived via the opening/closing circuit 13 that is turned on and off in response to the playing operation.

The sound source signal derived in response to this key operation is
A filter circuit 14 forms a tone as appropriate to form a musical tone signal, and this musical tone signal is taken out via an amplitude modulation circuit 15 that adds a modulation effect, and after being appropriately amplified by an amplifier 16, is supplied to a speaker 17. , to be pronounced as a performance sound.

For the amplitude modulation circuit 15, a first oscillator 1 with an oscillation frequency of 7 Hz, for example, corresponding to the tremolo period is connected to the amplitude modulation circuit 15.
8, or oscillation frequency 0.7 corresponding to the chorus period
An oscillation signal from a second Hz oscillator 19 is selected by a changeover switch 20 and supplied as a modulation signal.

That is, when the selector switch 20 is turned on to the first oscillator 18 side as shown in the figure, the musical tone signal obtained in response to the key operation on the keyboard 12 is
The amplitude is modulated at a frequency of Hz, and a tremolo effect is added to the performance sound obtained from the speaker 17.

Further, when the changeover switch 20 is changed from the state shown in the figure, the performance sound is modulated by 0.7H2 to express a chorus effect.

However, when such an effect circuit is used, when the changeover switch 20 is changed during a performance, the modulation signal to the amplitude modulation circuit 15 changes from 7Hz to 0.7H7 or 0.7H7.
The frequency suddenly changes from 7 Hz to 7 Hz, and the effect of the performance sound changes rapidly.

For this reason, the effect of the performance sound comes to be expressed with a very uneasy feeling, and the performance sound expression of the electronic musical instrument becomes unnatural.

This idea was developed in view of the above points, and it is an electronic system that allows the switching transition to occur naturally even when changing the modulation effect of musical tones, and allows the naturalness of the performance effects of electronic musical instruments to be fully demonstrated. This is intended to provide an effect circuit for a musical instrument, in which oscillation signals from modulating oscillators with different oscillation frequencies are taken out through switching circuits that are controlled to open and close by effect selection means. It is characterized by controlling opening and closing with a time constant.

An embodiment of this invention will be described below with reference to the drawings.

FIG. 2 shows its configuration, and the amplitude modulation circuit 15 is supplied with a musical tone signal corresponding to a performance operation in the same way as shown in FIG. 1, and the output signal is outputted from a speaker. .

The amplitude modulation circuit 15 is supplied with 7 Hz and 0.7 Hz oscillation signals from modulation oscillators 18 and 19 as modulation signals via VCAs 21 and 22 (voltage controlled variable gain amplifiers), respectively.

The VCAs 21 and 22 act as opening/closing circuits, and their amplification gain control signals, that is, opening/closing control signals, are applied to the source electrodes of field effect transistors 23 and 24, respectively.
Supplied from the drain electrode.

In this case, the transistors 23 and 24 are configured to supply a potential signal of +v2 to their respective drain electrodes and ground their source electrodes, and are connected to VCA2 with a common gate electrode signal.
The structure is such that the amplification gains of 1 and 22 are controlled reciprocally.

The gate control signals for the field effect transistors 23 and 24 are selected by the selection switch 25.
This switch 2 is formed with V or ground potential.
5 is supplied to the gate electrodes of transistors 23 and 24 via a time constant circuit 26 consisting of a variable resistor VR and a capacitor C.

That is, when the selection switch 25 is in the state shown in the figure, the field effect transistors 23 and 24 are activated at a potential of +Vl.
The gate electrode is controlled, and the drain and source are set to be conductive.

Therefore, a +V2 control signal is supplied to the VCA 21, and a 7Hz signal from the first oscillator 18 is supplied as a modulation signal to the amplitude modulation circuit 15, so that a tremolo effect is added to the musical tone.

At this time, the ground potential is supplied to the VCA 22, and its amplification gain is lost, so the 0.7H signal from the second oscillator 19 is
The second signal is never taken out as a modulation signal.

In this state, capacitor C is charged with +v1.

When the selection switch 25 is switched to the ground side in this state, the capacitor C is discharged via the variable resistor VR, and the potentials of the gate electrodes of the transistors 23 and 24 are shifted toward the ground.

That is, the control potential for VCA21 approaches the ground potential according to the time constant of time constant circuit 26, and VCA21 approaches the ground potential according to the time constant of time constant circuit 26.
On the contrary, the control potential of 2 changes so as to approach +v2, and the modulation signal to the amplitude modulation circuit 15 changes from the 7Hz signal of the first oscillator 18 to the 0.7H signal of the second oscillator 19.
The signal gradually changes to z.

That is, the tremolo modulation effect on the musical tone is gradually felt, the chorus effect is gradually added more strongly, and the tremolo effect is switched to the chorus effect.

In this case, the switching time constant when switching this effect is the variable resistance V
It can be controlled arbitrarily with R.

That is, according to the effect circuit as described above, each of the tremolo and chorus effects can be switched and selected using the selection switch 25, but when the button is switched, the effect added to the performance sound suddenly changes from one to the other. Switching is carried out continuously without any change.

Therefore, even if you change the effect while playing,
The performance sound effect changes naturally and does not give unnaturalness to the performance expression.

In the above embodiment, a case has been described in which the musical tone is amplitude modulated, but as shown in A of FIG. 3, signals B, B, and D are transmitted to the musical tone signal circuit using clock pulses.

When using an analog delay element 27 of a size larger than 5, angular modulation can be added to the musical tone signal, and other vibrato effects such as tremolo can also be controlled.

In this case, the clock signal for the analog delay element 27 is generated by VC028 (variable frequency oscillator),
The oscillation frequency control signal of this VC028 is
It is sufficient to obtain it from A21 and A22.

In addition, as shown in B of the same figure, a VCF29 is installed in the musical tone signal circuit.
If you insert a (voltage side type variable filter),
It can perform timbre modulation, and if the oscillation frequency of the sound source oscillator 30 is controlled as shown in Figure 0, pitch modulation, that is, vibrato effect can be controlled.

In the above embodiment, two modulation oscillators were used, but it is also possible to install a larger number of modulation oscillators to perform multiple effect switching controls, and to control amplitude, angle, timbre, and tone height. By selecting a combination of the modulation means and the modulation frequency, it is possible to perform additional switching control with naturalness of various effects.

Furthermore, although a VCA is used as the opening/closing circuit, any other arbitrary gate circuit may be used, and the switching specifying means having a time constant for this opening/closing circuit may also be configured in any other manner.

As described above, according to this invention, by controlling the output signal amplitudes of two oscillators inversely when switching the modulation frequency for musical tones, for example, by controlling the output signal amplitudes of two oscillators inversely, it is possible to create a transient phenomenon in an electronic musical instrument without causing discomfort. This makes it possible to perform additional control of the modulation effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram explaining a conventional effect circuit, FIG. 2 is a block diagram explaining an effect circuit according to an embodiment of the present invention, and A to C in FIG. 3 respectively show other examples of modulation means. FIG. 11... Sound source circuit, 12... Keyboard, 13... Open/close circuit, 15... Amplitude modulation circuit, 18.19... Oscillator, 21° 22... VCA, 23, 24... Field effect transistor, 25... selection switch, 26.
...Time constant circuit.

Claims (1)

[Scope of utility model registration request] A plurality of modulation signal generators each generate a modulation signal of a different frequency, a plurality of switching circuits to which modulation signals from each of the generators are supplied, and a musical tone is produced by the modulation signal derived from each switching circuit. A modulation circuit that adds a modulation effect, a selection circuit that selectively generates a switching designation signal for the switching circuit, and an output of the switching circuit that is selectively designated in response to the rising edge of the switching designation signal from the selection circuit. An electronic device comprising time constant control means for controlling the opening and closing so that the output amplitude gradually increases from zero, and also controlling the opening and closing of a previously specified switching circuit so that the output amplitude gradually decreases toward zero. Instrument effect circuit.