JPS58156209A - Tone control circuit - Google Patents

Abstract

PURPOSE:To avoid the difference of cut-off frequencies during the boosting and cutting-off, by providing feedback and feedforward signal lines and then setting a filter and a filter level control circuit to these signal lines. CONSTITUTION:An audio signal Ein is supplied to adders 11 and 12, and at the same time the output of the adder 11 is fed back to the adder 12. The output of the adder 12 is applied to the adder 11 via an LPF13 and a feedback quantity controlling adder 14. A control signal KL having response of a low band is applied to the adder 14. The output signal of the adder 11 is supplied to a circuit including an HPF23, and the response of a high band is controlled by the voltage KH for control of high band response which is applied to a terminal T4. As a result, the cut-off frequency of the boosting state of a low or high band can be set at the same level as the cut-off frequency of the cutting-off state.

Description

DETAILED DESCRIPTION OF THE INVENTION A tone control circuit as shown in FIG. 1 has been considered.

That is, in FIG. 1, audio signal 1! When the addition ia circuit (1) K is supplied through the input terminal T1, it is supplied to the low-pass filter (2) and the low frequency component II is extracted. Then, this low frequency component ML is supplied to the multiplier 11#I(4)K through the differential amplifier (3), and the terminal T! Control signal K for low frequency response from
L(-0,1!l≦KL≦2.18) is multiplied by - road (4)
From the multiplication circuit (4), multiplication signals KL and l are supplied.
L is scattered, this signal is supplied to the adder circuit (1), and the adder signal B! 11 - gln + KL @ 14 is hired.

Therefore, as shown in the second HK, the sign of the signal KL and the large 1
8, the low frequency range of the signal E1 can be varied within a range of ±10 dB.

Then, this signal 4# is supplied to the differential amplifier (5)K and also to the low-pass filter 467K to extract the mid-low frequency component CB*-11).
lr-III) is supplied to the differential amplifier (5), and the differential amplifier (5) outputs a difference signal EH1 between the two input signals, that is, a high frequency component B11. Then, this high frequency component - is supplied to the multiplier circuit (7) K, and the terminal T
A high frequency response control signal ~ (-0, 11≦ and ≦116) is supplied to the multiplier circuit (7) K from 4 to the multiplier circuit (η
A multiplication signal - III is taken out from K.
H@- and signal]! 1 is supplied to the adder circuit (8), and the addition signal 'IAout Bout = El +KH111H is taken out to the output terminal T.

Therefore, as shown in FIG. 2, the high frequency range of the signal B(2)t can be changed within a range of ±1011B in accordance with the sign and magnitude of the signal xH.

In this manner, the tone control circuit shown in FIG. 1 can obtain the characteristics shown in the second rlAK by controlling the signals Kl and KH.

However, in this case, in this tone control circuit, as is clear from FIG. 3, the cutoff frequency when boosting the low or high range is different from the cutoff frequency when cutting.

Furthermore, as shown in FIG. 3, the changes in the low-frequency and high-frequency responses to the signals Kl and hH6c become non-linear.

This invention seeks to solve these interlayer points.

Regarding the example above, ``'C's explanation error.

In FIG. 4, the audio signal Bin is input to the input terminal T.
When the adder circuits aυ and QaK are supplied through the adder circuit a3, the output signals from the adder circuit α are supplied to the output signals "11 to 嫂 5a", and the adder circuit a3 outputs the adder signal (Nin+i!
tt) is retrieved. And this signal (TAin
+PSll ) is supplied to a low-pass filter 0 having a transmission qII property of 1+8L (SL = j m CLRL ) to produce a low-frequency component "1m", and this low-frequency component P'1m is supplied to a multiplier circuit α At the same time, a low frequency response control signal KL (-0,52≦Kl≦0.52) is supplied to the multiplication port *u41 through the terminal T3, and the multiplication signal KL is output from the multiplication circuit α轡.
・Mls is taken out and this signal is added @(11)K
Supplied.

Therefore, the output signal "11" of the addition 11JIQI is.

no = lin + Kh@glB Therefore, becomes.

That is, for the original signal Bin, the circuit (13 to a
Through 4, the signal Ffl is fed back, and the signal Bin is also fed back. It will be under control.

Then'C, this signal Fill is added to the adder circuit C! 1),
At the same time, the output signal y7 from the adder circuit a
&out car is taken out, this signal Bout is supplied to the addition circuit @, and the addition circuit w&@ outputs the addition signal (E11+
n(2)t) Force 1 is extracted. Then, the signal of B (I
It is supplied to the no-i pass filter 21 which has a transfer characteristic of H 1+8H (8n=jωCHR), and the high-frequency component "!1" is taken out, and this high-frequency component E2m is supplied to the multiplication port wr■. At the same time, a high frequency response control signal KM (-0, 52≦xH≦0.52) is supplied to the multiplication circuit (to) through the terminal T4 [from the multiplication circuit Qa, a multiplication signal Kn.
gas is taken out and this signal is sent to the adder circuit C? m) K supplied.

Therefore, the output signal Bout of the adder circuit Qυ is as follows.

In other words, the signal "11K" is also subjected to refeedback and feedforward by the circuits Q to form the signal Bout.
is the output terminal T! It is taken out.

According to Nakasei, as shown in FIG. 5, by changing the signal KL within a range of ±0.52, the signal 1! The low frequency response of out changes within the range of ±1QdH, and the signal KM changes within the range of ±0.52.
Therefore, the high frequency response of the signal Bout is ±IQ dB
Varies within the range of .

And in this case, Iris 5! As IK also shows, the signal Bo
When the low and high ranges of ut are boosted or cut, the cutoff frequency does not change, and the relationship between the low and high range responses A of the signal Eout to the signals KL and KaK is as follows. K: KL or K.

This is also shown by Iris 111IK.5 to -0,52
In the range of ≦ to ≦0.52, it becomes almost a straight line, that is,
Turtle, signal B (2) when changing signals KL and icH
The low and high frequency responses of t change almost linearly.

In addition, since all the circuits αυ to ■ can be current-operated, when integrated into an IC, the filter Q31.

Variations in the resistors that make up the filter (131, CI!3) do not become a problem, and the capacitors that make up the filter (131, CI!3) can also be made as small as 40pFii, making it suitable for IC implementation. At the same time, the effect of using IC is significant.

Figure 7 shows the multiplier circuit Q4), c! 4, which has a double-balance fIjIK configuration, and its multiplication output is taken out by a current mirror path.

In the example shown in FIG. 8, circuit t23+, four signal lines are connected to circuit Q3. (14) li') This is the case where the signal line is provided in parallel.

Therefore, in this case, becomes.

Also, So9Ii! In the example shown, 0υ is a subtraction circuit, and (2) is an addition ii? 1, (to) to (to) indicate the multiplication circuit, and the multiplication circuit (to), (2) (and (to), 011
9) is configured as shown in FIG. 10, for example.

Therefore, in this case, becomes.

Furthermore, in the example shown in FIG. 11, aυ˜I represents an adder circuit, and ``(') represents a composite filter, and this filter 04 is configured as shown in FIG. 12, for example.

Therefore, if we let L, M, H be the human input signals of the terminals, M, and H of the filter, and let T be the output signal of the terminal T, and define six values as shown in Figure 1, we get: Become.

Therefore, in the tone control circuit of Diagram 11, becomes.

In FIG. 13, a multiplication circuit and an addition circuit are provided for the middle range.

Therefore, in this case, as shown in the 14th WAK, the mid-range response can also be controlled by the control signal KM.

In the example shown in the 151st IllK, the audio band is divided into five, and the response of each band is arbitrarily slowed down by control.
-a [stock] indicates a multiplication path, and ■ indicates a composite filter.

This filter (to) is configured, for example, as shown in No. 1611, and its characteristics are expressed as follows.

Therefore, in the tone control circuit shown in Figure 1.815, numerator - (1 + KA) + (1 + KIl) 81 + (1 - KC
) 5tSx 10(1+KD) 818g8m+(1+K
I) 81818384 denominator "" (1-KA) + (1-
Kn) 81+(1+KC) 818! +(”’D
)81”283+(1-K]c)81818384.

[Brief explanation of the drawing]

Figures 1 to 3, Iris 5 to 7, Figure 10, Figure 12, Figure 14, and Figure 16 are diagrams for explaining this invention.
4 stripes, 8 silks, 9-1 stripes 11, 13 stripes, 15 stripes
The figure is a system diagram of an example of this invention. 031, cat, h, - are filters. Figure 1 Figure 2 Figure 4 Figure 5 Figure 8 L Fl
+”11 Figure 14

Claims (1)

[Claims] A feedback signal line and a feedforward signal line are provided for the main audio signal line, and a filter is provided on the feedback signal line and the feedforward signal line, and the level of this filter I output is controlled. and a control circuit for extracting a tone control output from the main audio signal line by controlling the control path a.