JPH06132750A - Method and device for controlling bandsetting equalizer - Google Patents

Abstract

PURPOSE:To drastically simplify an operation by designating the maximum and minimum frequencies of bands and setting the center frequencies and Q of respective bands. CONSTITUTION:An audio signal from an audio unit 10 is transmitted to an amplifier 11 through a graphic equalizer 9. CPU 1 controls the graphic equalizer 9 through an input/output port 8. CPU 1 inputs the band change command of a user, the maximum frequency FL and the minimum frequency fH from a keyboard 4 and a detector 5 through the input/output port 8. CPU 1 is provided with ROM 2, and ROM 2 stores a program calculating fk and Qk for the respective bands based on fL and fH. The signal of the type of a source selected in the audio unit 10 is inputted from a source detector 6 to CPU 1 through the input/output port 8, and Fo and Q are set in accordance with the selected source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band setting type equalizer control method and apparatus.

[0002]

2. Description of the Related Art A listening room has its own sound field characteristics due to the resonance of the sound field there, and a characteristic in which a certain specific frequency is emphasized or attenuated is generated. A graphic equalizer has been conventionally used to correct such a sound field. As shown in FIG. 8, the conventional graphic equalizer is a band-pass filter F1 (S) ... Fn for dividing an input signal Vi into an amplifier A and dividing it into a plurality of bands.
(S) is provided to set each of these center frequencies f1 ... Fn. Further, each band filter F1 (S) ... Fn (S)
Are connected to variable resistors VR1 ... VRn, and by adjusting the resistors, band signals are amplified and attenuated to obtain an output signal Vo. Most of the bandpass filters are composed of LCR resonance circuits, and an arbitrary resonance frequency and Q can be obtained by the value of LC. The gain of each frequency is changed by utilizing the fact that the impedance decreases due to resonance. However, many of the resonance circuits actually used are semiconductor inductors as shown in FIG. 9 because the shape becomes large when the resonance frequency is made low. In this case, the center frequency is

[Equation 1] The sharpness of resonance is

[Equation 2] Becomes An IC in which a plurality of such resonance circuits are collected is integrated into a graphic equalizer. In this case, R1 and R2 in FIG. 9 are built in, so external capacitors C1 and C2 are selected. By doing so, the characteristics are decided. In this way, the graphic equalizer increases or attenuates the gain in a specific frequency band. On the other hand, the parametric equalizer has a configuration in which the frequencies fo and Q, which are important factors that determine the characteristics of the equalizer, can be independently varied. In this parametric equalizer, as shown in FIG. 10, a bandpass filter BPF capable of varying fo and Q is provided in the feedback loop of the amplifier, and the gain is adjusted by VR. An example of this BPF circuit is shown in FIG. The transfer function of this circuit is

[Equation 3] Therefore, if C1 = C2 and R3 = R4 are set here, Q = 1
/ 2a. Thus, fo can be independently changed by R3 (= R4) and Q can be independently changed by R2.

[0003]

However, since the center frequency and Q of each band are fixed in the above-described conventional graphic equalizer, even if the band in which the equalizer operation is desired is changed due to the change of the signal source or the speaker system, the equalizer operation is changed. The operating range, that is, the center frequency and Q do not change. In particular, in the case of an IC made of a semiconductor inductor, it is impossible to switch in real time because the capacitor on the printed board must be replaced. An example will be given in the case where the signal source changes. For example, as shown in FIG. 12, each center frequency is 5 with a 3-band graphic equalizer.
When set to 0, 700, 10 KHz (CAS
E1), CD and TAPE can be used effectively in all three bands, but FM does not work effectively at 10 KHz.
In M, 50Hz and 10KHz are almost useless.
When the center frequency is set to 125, 700, 4KHz (CASE2), AM can be used effectively in all three bands, but CD or TAPE is less than 100Hz or 5K.
Even if you want to adjust the frequency above Hz, you cannot do it. The same can be said when changing the speaker system.
On the other hand, in the parametric equalizer described above, the center frequency and Q can be set freely, but the conventional ones are all band independent operations, and there is a function of automatically dividing the band or automatically adjusting Q according to the bandwidth. However, there was a drawback that the operation was troublesome. The present invention aims to solve the above-mentioned problems of the prior art.

[0004]

In order to achieve the above object, a band setting type equalizer control method of the present invention comprises a band change judging step for judging whether or not a reproduction band of a reproduced signal has been changed and obtaining a judgment result, and the judgment. When there is a result, a reproduction band frequency acquisition step of reading the frequencies fL to fH, which are elements for determining the reproduction band of the reproduction signal, and the frequency f
Based on 1 to fh, a center frequency component setting step of calculating and setting a center frequency component fo according to the number of equalizer bands, and based on the center frequency component fo,
A selectivity setting step of setting the selectivity Q according to the bandwidths of adjacent bands.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. First, referring to FIG. 1, a device to be controlled will be described. The audio signal from the audio device 10 is sent to the amplifier 11 via the graphic equalizer 9. The graphic equalizer 9 is an n-band equalizer and has a number of bands (number of elements) from 1 to n.
And the center frequency fo and the selectivity Q are variable. The graphic equalizer 9 is configured to be controlled by the CPU 1 via the input / output port 8. CP
U1 is adapted to input the user's band change command and the highest frequency fL and the lowest frequency fH from the keyboard 4 and the detector 5 via the input / output port 8. And CPU
1 includes a ROM 2 in which a program for calculating fk and Qk for each band k based on fL and fH is stored. Further, the signal of the type of the source selected by the source detectors 6 to 10 is input to the CPU 1 through the input / output port 8
Input via, and depending on the selected source,
It is designed to set fo and Q. Fo and Q corresponding to this source are stored in the preset memory 3 in advance. Reference numeral 7 is a display for displaying the set center frequency fo.

A control method by the CPU 1 having the above-mentioned configuration will be described with reference to FIG. It is judged whether or not the user has issued an instruction to change the band (step 30), and if so, fL and fH are read from the detector 5 (steps 31, 3).
2). Then, with k = 0 (step 33), fk of each band from k = 1 to n is calculated according to the number of bands n of the graphic equalizer 9 (steps 35, 3).
6). The formula is

[Equation 4] This uses the program stored in the ROM 2 described above. The calculation formula of fk will be described later. Then, k is cleared (step 37), and similarly Q from k = 1 to n is calculated (steps 39, 40, 41,
42). In the case of the first band, this formula is

[Equation 5] In the case of 2 to (n-1) th,

[Equation 6] In the nth case,

[Equation 7] The calculation formula will be described later. Based on the above calculation, the CPU 1 controls the graphic equalizer 9 to set f1 to fn and Q1 to Qn of each band (step 4).
3), f1 to fn are displayed on the display 7 (step 4)
4). If there is no band change instruction in step 30, f1 to fn and Q1 to Qn for each signal source stored in the preset memory 3 are set (step 4).
6).

Now, assuming that the number of bands is 3, and the user inputs 100 Hz to 10 kHz,

[Equation 8] Becomes Since the whole area is logarithmically divided here, the bandwidths f1 to f2, f2 to f3,-(octave) are equal, and Q1 and Q2-are also equal, but the bandwidths are different. And Q will be different accordingly.

<Explanation of Expression for Finding f1 to fn> A general expression for finding each center frequency when a certain frequency band is logarithmically divided into n equal parts will be derived. First, the constant K is calculated from the fact that double is 1 (oct).

[Equation 9] As shown in FIG. 3, the total bandwidth fL to fH is OCTall (oc
t)

[Equation 10] If the divided bandwidth is OCTdiv (oct) as shown in FIG. 3,

[Equation 11] The k-th center frequency fk is (2k-1) * OCT from fL.
div is high,

[Equation 12] Becomes Further, as shown in FIG. 4, when fL and fH are also the center frequencies,

[Equation 13] Required by.

<Explanation of Expression for Obtaining Q1 to Qn> First, the definition of Q of the bandpass filter is as follows.

[Equation 14] In short, it is the ratio of the center frequency to the bandwidth as shown in FIG. The center frequencies f1 to fn of the n-band graphic equalizer are determined, and in order to improve the overlapping of the filter characteristics, as shown in FIG. 6, Q is set according to the bandwidth up to the center frequency of the adjacent filters. Is good. Therefore, the general formula to find Q is

[Equation 15] Can be expressed as It is necessary to determine K here, but there is no number that this is correct, so when I examined several commercialized graphic equalizers, I decided that around 7 was appropriate and set K = 7,

[Equation 16] However, when k = 1 ork = n, there is only one filter adjacent to each other as shown in FIG.

[Equation 17] If we apply the above formula,

[Equation 18] Becomes

According to the embodiment described above, it is possible to avoid a state in which the low band and the high band are out of the signal band and only the noise is adjusted even if the operation is performed, and the set band is set. It is possible to avoid a situation where the band is narrower than the band to be corrected, and it is possible to effectively use all the equipped bands. Further, it is possible to perform correction in a relatively narrow band, for example, to intensively correct only the middle range. Furthermore,
Since an appropriate Q is set according to the bandwidth, it is possible to improve the overlap of the band-pass filter characteristics and obtain an effective equalizer operation. Moreover, while having such an effect, it is only necessary to specify the bandwidth, and the operation is easy. Also,
An appropriate center frequency and Q can be set in advance according to each signal source, and there is an effect that an optimum setting can be performed by a simple operation.

As described above, the band setting type equalizer control method and apparatus of the present invention can set the center frequency and Q of each band only by designating the highest and lowest frequencies of the band, and can be operated extremely. It has the effect of being simple.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram for obtaining fk in the present invention.

FIG. 4 is an explanatory diagram for obtaining fk in the present invention.

FIG. 5 is an explanatory diagram for obtaining Qk in the present invention.

FIG. 6 is an explanatory diagram for obtaining Qk in the present invention.

FIG. 7 is an explanatory diagram for obtaining Qk in the present invention.

FIG. 8 is a block diagram showing an example of a conventional graphic equalizer.

FIG. 9 is a block diagram showing an example of a resonance circuit.

FIG. 10 is a block diagram showing an example of a conventional parametric equalizer.

FIG. 11 is a block diagram showing an example of a conventional bandpass filter.

FIG. 12 is an explanatory diagram of an operation of a conventional graphic equalizer.

[Explanation of symbols]

1: CPU, 2: ROM, 3: preset memory, 4:
Keyboard, 5: detector, 6: source detector, 7: display, 8: input / output port, 9: graphic equalizer,
10: audio equipment, 11: amplifier.

Claims (3)

[Claims] 1. A band change determination step for determining whether or not a reproduction band of a reproduction signal has been changed to obtain a determination result, and, when the determination result is affirmative, a frequency fL, which is an element for determining the reproduction band of the reproduction signal, a reproduction band frequency capturing step of reading fH; a center frequency component setting step of calculating and setting a center frequency component fo according to the number of equalizer bands based on the frequencies fL to fH; and a center frequency component fo based on the center frequency component fo. And a selectivity setting step of setting the selectivity Q according to the bandwidths of adjacent bands, and a band setting equalizer control method. 2. An equalizer control device for inputting a reproduction signal and reproducing and outputting the reproduction signal with a predetermined number of bands, a center frequency component and a selectivity, the frequency f being a factor for determining the reproduction band of the reproduction signal.
A frequency input setting means capable of inputting and setting L and fH, and a center frequency for calculating and calculating the center frequency component based on the frequencies fL, fH and the number of bands so as to be logarithmically equally divided. Component calculation means, and selectivity calculation means for calculating and calculating the selectivity according to the bandwidth of an adjacent band based on the center frequency component, the calculated center frequency component, selection A band setting type equalizer control device, which controls the reproduction signal based on the frequency and outputs the reproduction signal. 3. A reproduction signal detecting means for inputting the reproduction signal and detecting a type of the signal to obtain a signal detection signal; and a center frequency component calculating means for selecting the center frequency component calculation means according to the type based on the detection signal. 3. The band setting type equalizer control device according to claim 2, further comprising switching control means for controlling so as to switch and change to at least one of the center frequency component calculated and calculated by the degree calculation means.