JPH07129169A - Effect generating device - Google Patents

Abstract

PURPOSE:To prevent the tone of a musical sound signal emitted from thinning and the volume from lowering even in case the peak frequency (f) of band-pass filter, filtration center frequency, is heightened in an effector such as wow wow etc., which uses band-pass filter. CONSTITUTION:A band-pass filter 1 and a high-pass filter 2 are connected parallel, and a control circuit 9 to emit the peak frequency (f) of the band-pass filter 1 is equipped with a Q deciding circuit 9b for determination of the selectivity Q of the band-pass filter 1 and a HL deciding circuit 9d for determination of the output level factor HL of the high-pass filter 2. The Q deciding circuit 9b controls so that Q lessens with increasing (f) and the band width widens, while the HL deciding circuit 9d controls so that HL enlarges with increasing (f) and the output level of the high-pass filter 2 becomes large. This prevents the tone of the signal emitted from thinning and the volume from lessening even in the treble range where the higher harmonic component of the musical sound signal is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an effect device such as wah and wah for moving a center frequency of a bandpass filter for filtering a musical tone signal, and particularly to a high peak frequency (filtering center frequency) of the bandpass filter. It is related to the prevention of the attenuation of the tone color and volume when it reaches the range.

[0002]

2. Description of the Related Art Wah-wah is an effect device (effect device) mainly used in guitars, in which a bandpass filter with sharp characteristics is used to change the peak frequency of a musical tone signal to change the emphasized harmonics. It is an effect device that changes the timbre by doing so. The peak frequency is controlled by the output value of the foot pedal operated by the performer (guitar player) during the performance and the low-frequency signal output by the LFO. That is, in the conventional bandpass filter used for wah and wah, the filtering band is moved as shown in FIG. 4 (A) by the output of the foot pedal or LFO.

[0003]

However, the harmonic components of the musical tone are distributed around the fundamental frequency as shown in FIG. 7B, and the harmonic level becomes smaller as the frequency goes to the treble range. For this reason, there is a drawback that uniform effect characteristics cannot be obtained in all frequency bands only by raising and lowering the filtering band of the bandpass filter with the same characteristics regardless of the peak frequency as shown in FIG. That is, in this method, when the peak frequency of the bandpass filter is in the high frequency range, the tone color of the output musical tone becomes thin and the volume becomes small.

The present invention provides an effect device such as a wah-wah effect device in which even if the peak frequency of a bandpass filter is increased, the tone color of a musical tone to be output does not become thin and the volume does not decrease. To aim.

[0005]

The invention according to claim 1 of the present application comprises a bandpass filter for filtering an input musical tone signal, and a frequency control means for controlling a filtering center frequency of the bandpass filter. The effect device is provided with a bandwidth control means for controlling the filtering bandwidth of the bandpass filter to be wide / narrow depending on whether the filtering center frequency is above or below.

The invention of claim 2 of this application is a high-pass filter in an effect device comprising a bandpass filter for filtering an input musical tone signal, and a frequency control means for controlling a filtering center frequency of the bandpass filter. Is provided in parallel with the band-pass filter, and level control means for controlling the output level of the high-pass filter to high / low according to the upper / lower side of the filtering center frequency is provided.

[0007]

According to the present invention, the tone signal is filtered by the bandpass filter, and the filtering center frequency of the bandpass filter is controlled up / down by the frequency control means. When the filtered center frequency rises (becomes higher), the harmonic level of the musical tone signal to be filtered becomes smaller, but the bandwidth control means controls the bandpass filter to widen the bandwidth. As a result, harmonic components in a wide band are output in the high range.

According to the second aspect of the present invention, the tone signal is filtered by the bandpass filter, and the filtering center frequency of the bandpass filter is controlled up / down by the frequency control means. When the filtered center frequency rises (becomes higher), the harmonic level of the musical tone signal to be filtered decreases, but the output level of the high-pass filter connected in parallel with the band-pass filter is controlled to increase (level). Control means). As a result, in addition to the output of the bandpass filter, the components of the entire high frequency range output by the highpass filter are also output. Thus, even if the filtering center frequency of the bandpass filter becomes high, the tone color of the output musical tone signal does not become thin and the volume does not decrease.

[0009]

1 is a block diagram of an effect device according to an embodiment of the present invention. This effect device is wah wah,
The bandpass filter 1 and a control circuit 9 for increasing and decreasing the peak frequency of the bandpass filter 1 are provided. A bandpass filter 1, a highpass filter 2 and a changeover switch 7 are connected to an input terminal IN to which a tone signal is input from the outside. The bandpass filter 1 well filters only a part of the band of the input musical sound and outputs it. The peak frequency (filtering center frequency) f of the bandpass filter 1 and its selectivity Q are designated by the control circuit 9. The tone signal filtered by the bandpass filter 1 is input to the coefficient multiplier 3. A coefficient BL that determines the output level of the bandpass filter 1 is input to the coefficient multiplier 3 from the control circuit 9. The tone signal input from the bandpass filter 1 is multiplied by this BL and then input to the adder 5.

On the other hand, the high-pass filter 2 is for supplementarily adding and emphasizing the treble component of the tone signal when the peak frequency of the band-pass filter 1 is set in the treble range, and need not be emphasized. The cutoff frequency fc is set to several tens Hz to several hundreds Hz to cut the low-pitched sound part. The tone signal input to the high pass filter 2 is cut in the low frequency range and output to the coefficient multiplier 4. The coefficient multiplier 4 receives the coefficient HL that determines the output level of the high-pass filter 2 from the control circuit 9. The tone signal input from the high pass filter 2 is multiplied by this HL and then input to the adder 5. In the adder 5, the components passed through the band pass filter 1 and the high pass filter 2
And outputs the result to the external output terminal OUT. When this device is configured by an analog circuit, the external output terminal OUT is connected to an audio device such as an amplifier. When this circuit is configured by a digital circuit, the external output terminal OUT is connected to the D / A converter.

The control circuit 9 controls the peak frequency f output to the bandpass filter 1, the selectivity Q, the output level coefficient BL of the bandpass filter output to the coefficient multiplier 3 and the coefficient multiplier 4 as described above. The output level coefficient HL of the output high-pass filter is generated. Therefore, the control circuit 9 includes an f conversion circuit 9a, a Q determination circuit 9b, a BL determination circuit 9c, and an HL determination circuit 9d. The f conversion circuit 9a is a circuit that converts the level data input from the level detection circuit 8 into a peak frequency f. The Q determination circuit 9b is a circuit that determines the selectivity Q of the bandpass filter based on the peak frequency f. BL decision circuit 9c
Is a circuit that determines the output level BL of the bandpass filter based on the peak frequency f. HL determination circuit 9d
Is a circuit that determines the output level HL of the high-pass filter based on the peak frequency f. f is controlled to be low ← → high in accordance with the small ← → high level data. Q, BL, and HL are determined based on f so as to maintain the relationships shown in FIGS. 2A and 2B, respectively.

The level detection circuit 8 detects the level of the external input terminal IN or the external controller 6 which is selectively connected by the changeover switch 7. That is, when the changeover switch 7 is switched to the external input terminal IN side as shown in the figure, the volume level of the input musical tone signal is detected. When the changeover switch 7 is switched to the external controller 6 side, the operation amount level of the external controller is detected. The detected level is output to the f conversion circuit 9a of the control circuit 9 as level data. The external controller 6 is, for example, a foot pedal.
Here, referring to FIGS. 2 and 3, the peak frequency f and
The relationship between the selectivity Q, the bandpass filter output level coefficient BL, and the highpass filter output level HL will be described. In FIG. 2A, when f becomes high, Q is inversely proportional.
Is determined to be low. This is because, as described above, in the high tone range of the musical tone signal, since the level of the harmonic component is low, the selectivity is slowed down to widen the bandwidth and pass the components in the wide tone range. In addition, in FIG.
As f becomes higher, the output level of the high-pass filter 2 is raised so that HL components are gradually output in order to pass the high-frequency components well. On the other hand, when f is low, the wah-wah effect is reduced when a high-pitched tone is output.
It is set so that L becomes 0.

Further, the output level coefficient BL of the bandpass filter 1 is set to gradually decrease as f increases. This is because when f becomes high, the bandpass filter 1 becomes wide band (Q becomes small) and HL becomes high.
Is output and the output signals of the high-pass filter 2 are added, so that the output levels are balanced. As described above, in this embodiment, when f is increased, Q is decreased and HL is increased to maintain the timbre / volume. However, the high pass filter 2 is not used and only Q is decreased, or band pass is performed. Even if the HL of the high-pass filter 2 is increased without changing the Q of the filter 1, some effects can be obtained. The determination of the coefficient as described above may be performed by storing a table as shown in FIGS. 2A and 2B and referring to the table, or by storing a function representing the above relationship. It may be performed by a function calculation.

When processing the tone signal from the input terminal IN based on the coefficient thus determined, the filtering characteristic at the external output terminal OUT is as shown in FIG. That is, when the level data output by the detection circuit 8 is low (when the input level of the tone signal is low or when the external controller 6 is not operated (the foot pedal is not depressed)), the peak frequency f is low and Q
Is large (the filtering band is narrow), but the level data output by the detection circuit 8 becomes large (when the input level of the musical tone signal becomes large or when the external controller 6 is operated (the foot pedal is depressed)) , The peak frequency f increases and the Q of the bandpass filter 1 increases.
Becomes smaller and the filtering bandwidth becomes wider, and HL is output and the output signal level of the high-pass filter 2 rises to output the harmonic components of the entire treble range. When f is in the high frequency range, by adopting such a filtering band characteristic, the tone does not become thin and the volume does not decrease even if the frequency to be emphasized shifts to the high frequency range. You can even apply the effect of wah.

[0015]

According to the present invention, even if the peak frequency of the bandpass filter becomes high and the level of the harmonic component of the musical tone signal to be filtered becomes small, the filtering bandwidth becomes wide, so that the musical tone to be output is outputted. The tone does not become thin and the volume does not decrease. Further, according to the present invention, even when the peak frequency of the bandpass filter becomes high and the level of the harmonic component of the musical tone signal to be filtered becomes low, the high frequency range output by the highpass filter is output to the output signal of the bandpass filter. Since the harmonic component signal is also added, the tone color of the output musical tone does not become thin and the volume does not decrease.

[Brief description of drawings]

FIG. 1 is a block diagram of an effect device (wow, wah) according to an embodiment of the present invention.

FIG. 2 is a diagram showing a coefficient table of the same effect device.

FIG. 3 is a diagram showing changes in filtering characteristics of the effect device.

FIG. 4 is a diagram showing changes in filtering characteristics of a conventional effect device.

[Explanation of symbols]

 1-Band pass filter 2-High pass filter 9-Control circuit 9a-f conversion circuit 9b-Q decision circuit 9c-BL decision circuit 9d-HL decision circuit

Claims (2)

[Claims] 1. An effect device comprising a bandpass filter for filtering an input musical tone signal and a frequency control means for controlling a filtering center frequency of the bandpass filter, wherein: And a bandwidth control means for controlling the filtering bandwidth of the bandpass filter to be wide / narrow. 2. An effect device comprising a bandpass filter for filtering an input musical tone signal and frequency control means for controlling a filtering center frequency of the bandpass filter, wherein a highpass filter is provided in parallel with the bandpass filter. An effect device provided with level control means for controlling the output level of the high-pass filter to a high level or a low level depending on whether the filtering center frequency is above or below.