JPS61108211A - Graphic equalizer device - Google Patents

Abstract

PURPOSE:To keep a sound level always at an initially set level by correcting automatically the sound volume change of a reproduced sound attended with the change in the frequency characteristic of a graphic equalizer circuit. CONSTITUTION:An audio signal is fed externally to an electronic VR (variable resistor) 1 for sound volume adjustment at first. The graphic equalizer circuit 3 is connected to the output terminal of the electronic VR1 via an adder 2. The gain of the electronic VR1 and the frequency characteristic of the graphic equalizer circuit 3 are controlled by a control circuit 4. Further, a pink noise generator 6 and a frequency characteristic detection circuit 7 for automatic sound field correction are provided. The pink noise generator 6 generates pink noise in response to a command from the control circuit 4 and applies it to the adder 2. Moreover, the gain level of each adjusting band of the graphic equalizer circuit 3, that is, the frequency characteristic is displayed on a display device.

Description

[Detailed description of the invention] Technical field The present invention relates to a graphic equalizer device.

BACKGROUND ART In a sound reproduction system equipped with a graphic equalizer device, if the frequency characteristics of the graphic equalizer device are changed, the volume of the reproduced sound output from a speaker or the like usually changes. For example, boost the gain by 12 (IB) in each adjustment band of a graphic equalizer device.
The raised platform has a boost of about 20 dB in the entire band, which is equivalent to raising the gain by 20 dB with the volume adjuster. Therefore, in the past, in order to use a graphic equalizer device only to change the frequency characteristics, the user had to adjust the volume after changing the frequency characteristics of the graphic equalizer device.

Therefore, an object of the present invention is to provide a graphic equalizer device that makes it possible to maintain a preset volume level without performing a volume adjustment operation even if the frequency characteristics are changed. .

The graphic equalizer device of the present invention detects the amount of gain change caused by the change in at least the middle range of the frequency characteristics when the frequency characteristics of the graphic equalizer means changes, and adjusts the electronic volume control so as to cancel out the detected amount of gain change. It is characterized by changing the gain of variable gain amplification means such as.

So-LJL Embodiments of the present invention will be described below with reference to the drawings.

In the graphic equalizer device shown in FIG. 1, which is an embodiment of the present invention, an audio signal is first supplied from the outside to an electronic VR (volume) 1 for volume adjustment.

A graphic equalizer circuit 3 is connected to the output end of the electronic VR1 via an adder 2. The gain of electronic VR1 and the frequency characteristics of graphic equalizer circuit 3 are controlled by control circuit 4. The control circuit 4 is preferably a digital control circuit consisting of a microcomputer. A keyboard 5 is connected to the control circuit 4 in order to generate control commands for the frequency characteristics of the graphic equalizer circuit 3. The output end of the graphic equalizer circuit 3 serves as the output end of the present device, and a power amplifier (not shown) that drives a speaker (not shown) is usually connected to the output end.

Further, the graphic equalizer device according to the present invention is provided with a pink noise generator 6 and a frequency characteristic detection circuit 7 for automatic sound field correction. The pink noise generator 6 generates pink noise in response to a generation command from the control circuit 4 and supplies it to the adder 2 . The frequency characteristic detection circuit 7 includes a microamplifier 8 that amplifies the audio signal collected and output by a microphone (not shown) and a plurality of different BPFs (band pass filters), and is supplied with the output signal of the microamplifier 8. an A/D converter 1 that converts the output signal of the filter circuit 9 into a digital signal and supplies it to the control circuit 4.
Consists of 0. The center frequency of each BPF of the filter circuit 9 is equal to the center frequency of each adjustment band of the graphic equalizer circuit 3, and the output signal of each BPF is sequentially detected and output from the filter circuit 9 as a DC voltage.

Note that the gain level, ie, the frequency characteristic, of each adjustment band of the graphic equalizer circuit 3 is displayed on a display (not shown).

Next, the operation of the graphic equalizer device according to the present invention having such a configuration during manual operation will be described in accordance with the operating procedure of the control circuit 4 shown in FIG. 2.

In this procedure, when manual operation is selected,
An initial average value Go of the gain levels of each adjustment band of the graphic equalizer circuit 3 is calculated and stored in the memory A (step 51). The number of adjustment bands of the graphic equalizer circuit 3 is n, and the gain level of each adjustment band is G+.
, G2...Gn, the average value of the gain level Qa
is calculated by the following formula.

Ga = (ΣGn)/n [clB] ・ (1
) The average value Qa calculated by this calculation formula (1) immediately after manual operation selection is the initial average value Go. Note that if the initial average value Go is calculated in advance and stored in a memory or the like, it is not necessary to calculate it in this way. Also, in the control circuit 4, GEQ data regarding the gain level of each adjustment band of the graphic equalizer circuit 3 and electronic VR are stored.
The gain of I−VR data for GV is stored in a predetermined memory, and the average value Ga is added from the GEQ data.

Next, it is determined whether a key is operated on the keyboard 5 and a control signal representing characteristic change data is supplied to the control circuit 4 (step 52), and this step 52 is continued until the control signal is supplied.
is executed repeatedly. When a control signal is supplied, the contents of the control signal, that is, the contents of the GEQ data are converted according to the characteristic change data, and thereby the gain of each adjustment band is increased or decreased in order to control the frequency characteristics of the graphic equalizer circuit 3 ( Step 53).

Then, the average value Qa of the gain level of each adjustment band after the characteristic change of the graphic equalizer circuit 3 is calculated from the GEQ data of the new content using equation (1) (step 5
4) The calculated average value Ga is stored in memory B (
Step 55). Next, the initial average value Go is stored in the memory 86.
The level difference ΔG between the average value Ga and the initial average value GO is calculated from the beginning (step 56).

As shown in Figure 3, the initial average value GO is O [dB],
When the frequency characteristics of the graphic equalizer circuit 3 are changed as shown by the solid line a, the center frequency fl+ of each adjustment band changes.
Average value Qa of gain level at f2+...f7
The fluctuation range of (broken line b) with respect to the initial average value GO is the level difference ΔG. Then, the content VR of the VR data, that is, the gain -GV (however, GV≧O) of the electron VR1 is read out (step 57), -hΔG■ is added to the gain -GV, and the addition result value is used as the new VR. data (step 58), and the gain of the electronic VR1 is controlled according to this VR data (step 59). Here, h is a correction constant greater than 1, and is a constant for correcting the fact that when all adjustment bands are boosted, the gains of adjacent bands will overlap, so the gain change will not necessarily be equal to the level difference ΔG. It is.

In this way, when the gain of electron VR1 is controlled, the average value G
a is stored in memory A as a new initial average value Go (
Step 60), step 52 is executed again.

In the graphic equalizer device according to the present invention, the average value Qa of the gains in each adjustment band of the graphic equalizer circuit 3 is calculated, and the level difference ΔG between the average value Qa and the initial average value Go is obtained. However, it is not limited to this. For example, when the frequency characteristics of the graphic equalizer circuit 3 are flat over the entire band as shown in Figure 4(a), and when the gain in the mid-range is higher than the gain in the low and high frequencies as shown in Figure 4(b). The audible difference between the case where the frequency characteristic is low and the average value Gx of the gain level of the whole band is equal to the gain 1% G Since the average value Ga of the gain only in the mid-range of the characteristic shown in b) is lower than the average value G×, it can be predicted that the frequency characteristic shown in FIG. 4(a) will sound higher in volume. Therefore, the operating procedure of the control circuit 4 may be as shown in FIG. That is, in this procedure, first, the initial average value GO of the gain level of only the mid-range adjustment band of the graphic equalizer circuit 3 is calculated and stored in the memory A (step 51a). Step 52.5 is then carried out similarly to the operating procedure shown in FIG.
3 is executed, and it is determined whether the gain of the adjustment band belonging to the middle range of the graphic equalizer circuit 3 has been increased or decreased (step 61). If the gain of the adjustment band belonging to the middle range is not increased or decreased, step 52
is executed again. On the other hand, when the gain of the adjustment band belonging to the mid-range is increased or decreased, the average value Ga of the gain level of the adjustment band belonging to the mid-range after the characteristic change of the graphic equalizer circuit 3 is calculated based on the GEQ data ( Steps 54a) and 55 are sequentially executed in the same manner as the operating procedure shown in FIG.

In this embodiment of the present invention, the low and high frequency characteristics of the graphic equalizer circuit 3 are ignored, and the gain of the electronic VR 1 is adjusted in response to changes in the frequency characteristics only in the midrange. The average value of the gain level for each adjustment band may be calculated by performing so-called weighting on the frequency range, middle frequency range, and high frequency frequency range. For example, the weighting is done as follows: low range: middle range: high range = 1:2:1. Further, weighting may be applied to each adjustment band.

Next, when performing automatic sound field correction, the detection value Dn (n=1
．． 2...) and the average value Da of all of them ΔD
In the method of inverting n (=Dn - Da) to obtain GEQ data, since Da = Do, it is not possible to obtain level differences in all adjustment bands, and it is difficult to determine what kind of frequency characteristics the graphic equalizer circuit 3 has. Even if the gain changes, the gain cannot be corrected. Therefore, as shown in Figure 4, electronic VR
to adjust the gain. In this case, step 52
Then, it is determined whether an automatic sound field correction command has been generated or not.
In step 53, the contents of the GEQ data are changed according to the detected value [)n, thereby increasing or decreasing the gain of each adjustment band of the graphic equalizer circuit 3.

FIG. 5 shows the operating procedure of the control circuit 4 when pink noise is generated during automatic sound field correction and the gain level is controlled according to the detected value. In this procedure, first, it is determined whether an automatic sound field correction command has been generated by operating the keyboard 5 (step 71), and if no automatic sound field correction command has been generated, the execution of step 71 is repeated. It will be done. When an automatic sound field correction command is generated, a pink noise generation command is generated to output pink noise from the speaker (step 72). In response to the pink noise generation command, a signal containing only the pink noise component is supplied from the pink noise generator 6 to the power amplifier via the adder 2 and the graphic equalizer path 3 to drive the speaker. At this time, no audio signal is supplied to the electronic VRI. When pink noise is emitted into the listening space in this way, the microphone amplifier 8 is adjusted such that the detection value [)n of each adjustment band obtained from the frequency characteristic detection circuit 7 is near the center of the input range of the A/D converter 10. The gain is adjusted (step 7
3) Then, the detected values [)n of each adjustment band are sequentially read as data (step 74). The average value Dn of all detection values D+, D2, etc. of each adjustment band and the average value DaI'h of the detection values only of the adjustment band belonging to the middle range
It is calculated and stored in the memory (step 75), and GEQ data is created by comparing the detected value [)n and the average value [)a for each adjustment band (step 76). Then, the gain of each adjustment band of the graphic equalizer circuit 3 is increased or decreased in accordance with the GEQ data (step 77).

After that, the gain of the microphone amplifier 8 is fixed (locked) (
At step 78), the detected values Qn of each adjustment band are sequentially read as data from the frequency characteristic detection circuit 7 again (step 79), and the detected value D+ is obtained.

The average value Da2 of the detected values only in the adjustment band belonging to the middle range among D2... is calculated (step 80).

Next, the difference ΔD between the average value Da+ and Da2 (=Da
l-Da2) is calculated (step 81), and VR data is read from a predetermined memory (step 82). The difference ΔD is subtracted from the VR data value VR, and the subtraction result value is used as new VR data (step 83), the gain of the electron VR1 is controlled according to this VR data (step 84), and step 71 is performed again. executed.

In addition, in the embodiment of the present invention described above, the electronic VR1
is provided before the graphic equalizer circuit 3, but the electronic VRI can be installed anywhere within the audio signal line, and if the electronic VR is other than the tonic IVR, the volume can be adjusted as a fader VR or a balance VR. Anything is fine as long as it can be adjusted.

Further, the operation of the control circuit 4 in the case of automatic sound field correction may be performed in a procedure other than that described above.

Summary of the Invention As described above, according to the graphic equalizer device of the present invention, the initially set volume level is always maintained because the volume change of the reproduced sound due to the change in the frequency characteristics of the graphic equalizer circuit is automatically corrected. There is no need to readjust the volume level every time the graphic equalizer device is operated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG.
5 and 6 are flow diagrams showing the operation of the control circuit in the device shown in FIG. 1, FIG. 3 is a waveform diagram showing the frequency characteristics of the graphic equalizer circuit related to the operation shown in FIG. 2, and FIG. This figure is a waveform diagram showing the frequency characteristics of the graphic equalizer circuit according to the operation shown in FIG. 5. Explanation of symbols of main parts 1... Electronic VR 2... Adder 3... Graphic equalizer circuit 4... Control circuit 5... Keyboard 6.
... Pink noise generator 7 ... Frequency characteristic detection circuit

Claims (1)

[Claims] a graphic equalizer means and a variable gain amplification means provided in a supply line of an audio signal to an electroacoustic converting means, and when the frequency characteristic of the graphic equalizer means changes, the frequency characteristic changes at least in the middle range. A graphic equalizer device characterized in that it detects the amount of gain change that has occurred, and changes the gain of the variable gain amplification means so as to cancel the detected amount of gain change.