JP2757717B2 - Effect giving device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an effect imparting device for changing the degree of an effect imparted to a musical tone exponentially.

[0002]

2. Description of the Related Art Conventionally, wahs, phasors and the like have been put into practical use as effect circuits for continuously changing the tone of a musical tone. Wah is a band-pass filter in which the peak frequency of the transmission characteristic moves continuously, and changes the tone by continuously changing the harmonic characteristics of the musical sound. The phasor uses an all-pass filter in which the phase delay characteristic changes continuously, and changes the tone by continuously changing the phase. The parameters for controlling the degree (speed and depth) of the effect application of such an effect circuit include operation amount data of various operators such as a pedal and a modulation wheel, and LFO.
Is generated on the basis of the periodic waveform in which is generated.

[0003]

The effect provided by the effect circuit such as a wah or a phasor is an effect caused by a characteristic change on the frequency axis. By the way, the listener's sensitivity to the frequency change is not a linear function but an exponential function.

For example, when the frequency changes from 10 Hz to 20 Hz and when the frequency changes from 100 Hz to 200 Hz, there is a 10-fold difference in frequency between 10 Hz and 100 Hz. Change). Therefore, when it is desired to keep the rate of change of the effect on the auditory sense constant, it is necessary to make the characteristic change exponentially.

However, the operation amount data of the general controller and the periodic waveform of the LFO change linearly when viewed on the time axis. For this reason, conventionally, the discrete data of the exponential function is stored in a table in a memory, and the exponential function value is obtained by accessing the table with the input data. However, this method has the drawback that a large memory is required, a complicated configuration for accessing the memory is required, and the cost is high.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an effect providing apparatus which can change parameters exponentially without having a function memory.

[0007]

SUMMARY OF THE INVENTION The present invention provides an effect imparting unit that imparts an effect to the input tone signal to the extent indicated by a parameter, and a parameter generating unit that generates the parameter. The apparatus is characterized in that the parameter generation unit is provided with a conversion unit that converts a parameter generated as a linear function to a value approximated to an exponential function value using a power function and outputs the converted value.

[0008]

According to the effect applying apparatus of the present invention, an effect is applied using parameters that change exponentially. Exponentially changing parameters are approximated by powers of magnitude. The power can be calculated simply by digital operation, and can be realized very simply by an operational amplifier circuit. This eliminates the need for a memory and a circuit for accessing the memory.

[0009]

FIG. 1 is a block diagram of an effect applying apparatus according to an embodiment of the present invention. This effect imparting device is a device which imparts an effect to an externally input digital tone signal by an effect circuit such as a phasor or a wah, converts the signal into an analog signal, and outputs the analog signal from a sound system. The digital tone signal is input to the effect applying unit 1. The effect imparting section 1 imparts various effects to the digital musical tone signal. The digital tone signal to which the effect has been added is converted to a D / A converter (DA
C) The signal is converted into an analog tone signal by 2). The tone signal converted to analog is output to the sound system 3. The sound system 3 amplifies the tone signal and emits the sound from a speaker or the like. Further, a modulation signal generating section 4 is connected to the effect applying section 1. Modulation signal generator 4
Is a circuit for generating a modulation signal to be input to the effect imparting unit 1. The effect imparting unit 1 increases / decreases the effect imparting amount and the change speed by the modulation signal. Control elements such as a pedal and a modulation wheel are connected to the modulation signal generator 4.

FIG. 2 shows an example of the effect imparting section 1. This circuit is a wah effect circuit. The wah effect circuit is a kind of bandpass filter. As shown in FIG. 3, the peak of the transmission characteristic is shifted on the frequency axis to change the overtone composition (harmonic characteristics) of the musical tone, thereby changing the timbre. This is the effect circuit to be turned on.

Note that the effect imparting section 1 uses DS in an actual device.
The Wah effect circuit and the phasor circuit shown in FIG. 4 are realized by a DSP and a microprogram for controlling the same. However, in this embodiment, the circuit is described by a hardware circuit for easy understanding.

In FIG. 2, the band-pass filter includes adders 10, 12, 14, 17, delays 15, 18, and coefficient multipliers 11, 13, and 16. Coefficient multiplier 1
By changing the coefficient input to 1, the Q of this bandpass filter can be changed. Further, the same modulation signal is input to the coefficient multiplier 13 and the coefficient multiplier 16, and the cutoff frequency of the bandpass filter is controlled by the modulation signal, and the transmission characteristic of the bandpass filter is changed and controlled. The details of this bandpass filter are disclosed in Japanese Patent Application Laid-Open No. 61-18212.

FIG. 4 is a diagram showing the configuration of the phasor effect circuit. In this circuit, a plurality of all-pass filters 20 to 2
4 are connected in series. The outputs of the second-stage and fourth-stage all-pass filters 21 and 23 are added and synthesized by an adder 29, and then added and synthesized with an input signal by an adder 30 to produce a left channel output. The outputs of the third-stage and fifth-stage all-pass filters 22 and 24 are added and synthesized by an adder 31 and then added and synthesized with an input signal by an adder 32 to obtain a right channel output. As a result, the tone signal input as a monaural signal can be output as a two-channel signal having a different phase, and a sense of spread of the tone can be obtained.

The all-pass filter has the following structure. A description will be given taking the all-pass filter 20 as an example. The all-pass filter 20 includes a delay 41, adders 40 and 42 provided before and after the delay 41, and a coefficient multiplier 4
3, 44. The output of the adder 42 is input to the adder 40 on the input side of the delay 41 via the coefficient multiplier 44. The coefficient multiplier 44 multiplies the output by a coefficient (modulated signal). The adder 40 adds the input tone signal and the output of the coefficient multiplier 44 and provides the result to the delay 41, thereby causing a phase delay. Coefficient multiplier 43
Multiplies the input tone signal by a coefficient (modulation signal) given from the outside, and inputs the result to an adder 42 connected to the output side of the delay 41. In the adder 42, the output of the coefficient multiplier 43 is subtracted from the output of the delay 41. This makes the frequency characteristics flat. As shown in FIG. 5, the phase delay increases as the frequency increases, but the degree is controlled by the coefficient input to the coefficient multiplier 43.

The outputs of the all-pass filters 21 to 24 are multiplied by predetermined coefficients by coefficient multipliers 25 to 28 and then added and synthesized to the left and right channels. Can be changed, and the feeling of spreading can be changed.

FIG. 6 is a diagram showing a configuration of the modulation signal generator 4. The selector 54 is connected to the LFO 50, the envelope extraction unit 51, and the control operator 52. The control operator 52 is connected to a selector 54 via a coefficient multiplier 53. The selector 54 is connected to a fourth power circuit 55. The fourth power circuit 55 is a circuit for raising the input data to the fourth power. The data output from the fourth power circuit 55 is output as a modulation signal via an inverter 56 and an adder 58.

The envelope extracting section 51 is a circuit for extracting and outputting the envelope of the input tone signal.
The control operator 52 is a control operator such as a pedal or a modulation wheel operated by a player. The operation amount data of the control operator is input to the coefficient multiplier 53. The coefficient multiplier 53 multiplies the manipulated variable data by a predetermined coefficient and inputs the data to the selector 54. On the other hand, the LFO 50 is an oscillation circuit that generates a triangular wave, and its frequency and amplitude (depth) are determined by input parameters. The LFO 50, the envelope extraction unit 51, and the coefficient multiplier 53 output data normalized to 0 ≦ x ≦ 1 (x: output of each unit).

The selector 54 inputs one of the triangular wave of the LFO 50, the envelope signal extracted by the envelope extraction unit 51, or the operation amount data of the control operator 52 to the fourth power circuit 55 based on the select signal. I do. The fourth power circuit 55 has two multipliers connected in series. Each multiplier squares the input signal. This is 2
The fourth power has been obtained by repeating the procedure several times. The fourth power converts the triangular wave into an exponentially changing waveform.

The inverter 56 is a circuit for inverting the data raised to the fourth power. The adder 58 is a circuit for shifting the inverted data by plus (1 × BIAS).

It should be noted that the adder 5 depends on the output destination of the modulation signal.
8, the shift amount is different, so the shift amount is determined based on the output destination of the modulation signal. Further, since the waveform to be used differs depending on the output destination of the modulation signal, the inverter 56
Is determined based on the output destination of the modulation signal.

The LFO 50 and the envelope extraction unit 5
1. The data of the control operator 52 is fetched in a time-division manner by the selector in a time-division manner, and after being processed by the circuit,
The signal is output to a predetermined circuit of the effect applying unit 1. This allows
LFO 50, envelope extraction unit 51, control operator 52
Can be used for different effect control.

The fourth power circuit 55 described above, y = x ⁴ (however, x: the input data, y: output data) is a circuit for performing an operation of, the y = x ⁴ curve as shown in FIG. 7 0 ≦ x ≦
In section ^{1, the} curve approximates to a y = 55.3 ^x-1 curve.
Therefore, a linear function change can be converted into an exponential function change by performing the fourth power operation. For example, a linear triangular wave output from the LFO 50 can be converted into a waveform obtained by combining exponential function curves as shown in the upper part of FIG.

By inputting this waveform to the effect imparting section 1, an audibly linear change can be realized.

Although y = x ⁴ is used as a function approximating the exponential function in the above embodiment, the function to be used is not limited to this. It is also possible to approximate in a section other than 0 ≦ x ≦ 1.

[0025]

As described above, according to the present invention, the effect imparted to a musical tone can be smoothly and audibly changed with a simple configuration by approximating an exponential function with a power function.

[Brief description of the drawings]

FIG. 1 is a block diagram of an effect imparting circuit according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of an effect applying unit (a wah circuit) of the effect applying circuit.

FIG. 3 is a diagram showing an effect of the wow circuit.

FIG. 4 is a diagram illustrating an example (a phasor circuit) of the effect imparting unit.

FIG. 5 is a diagram showing an effect of the phasor circuit;

FIG. 6 is a detailed block diagram of a modulation signal generator of the effect applying circuit.

FIG. 7 is a diagram showing a quartic function used in the modulation signal generator.

[Explanation of symbols]

Claims (1)

(57) [Claims] 1. An effect applying apparatus comprising: an effect applying section for applying an effect indicated by a parameter to an input tone signal; and a parameter generating section for generating the parameter. And a conversion means for converting a parameter generated as a linear function into a value approximated to an exponential function value using a power function and outputting the converted value.