JPH10136494A - Bass increase circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain clear bass increase and high efficiency of a power amplifier in sound reproduction. SOLUTION: This circuit has a bass rise detection control circuit which serially connects an LPF 1 that extracts bass elements in an inputted sound signal, a rectifier circuit 4 that is the subsequent stage of an amplifier 3 that amplifies an output signal from the LPF 1 and rectifies a signal level, a differential circuit 5 which detects the rise of a rectified signal level and an integrated circuit 6 that adjusts pulse width which is outputted from the circuit 5 and also has a volume control amplifier which performs level adjustment of an output of the LPF 1, adds only rising pulse width which is acquired by the circuit 6 and bass elements that pass through the LPF 1 to an inputted sound signal and attains bass increase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the enhancement of low-frequency range of sound reproduction. In particular, the present invention relates to bass reproduction of a TV set with poor bass reproduction.

[0002]

2. Description of the Related Art A speaker mounted on a TV set cannot reproduce a sufficient bass component due to size and shape restrictions, and digital high performance music sources such as BS (satellite broadcasting) and high definition are broadcast. Nevertheless, there was a problem that only poor bass reproduction could be enjoyed. In recent years, the number of occasions of connection with external source devices such as CDs and LDs has increased, and the need for bass reproduction has been desired.
Normally, the bass can be enhanced by boosting the bass with a tone control circuit (tone control). However, this tone control circuit is often implemented as an IC, and the dynamic range from the power supply used by the IC is usually increased. Once decided, naturally the amount of boost is limited. To compensate for this drawback, as shown in Japanese Utility Model Laid-Open No. 4-112599, a sound reproducing method for adding and amplifying only the low frequency component of a voice LR signal at a stage prior to a power amplifier and adding the result to the respective LR signals to enhance the bass. It has been known. Hereinafter, an example of bass enhancement will be described with reference to FIG.

In FIG. 4, reference numeral 10 denotes a filter block composed of an LPF for extracting low-frequency components and an HPF for extracting high-frequency components, 11 denotes an adder for adding only low-frequency components of the audio LR signal, and 12 denotes a signal level. And an amplifier 13 for amplifying the bass component of the amplified sound LR.
An adder 14 adds the high frequency component of the signal, a power amplifier 14 amplifies the power, and a speaker 15.

The operation of the above-structured bass enhancement will be described. The input audio LR signal is separated into a low-frequency component and a high-frequency component by the filter block 10, and only the low-frequency component is added by the adder 11. The added bass component is amplified according to the effect by the amplifier 12, added to the high tone component of the audio LR signal through the adder 13, and the audio signal of the entire band whose bass is enhanced is power-amplified by the power amplifier 14. Is reproduced from the speaker 15.

[0005]

However, in the above conventional configuration, the tone control is the same as the bass enhancement, and if the boost amount of the tone control is increased,
This is a method that can be solved, and measures for power supply to the IC and a method of expanding the dynamic range may be considered. However, although there is an effect of enhancing bass, the load on the power amplifier increases in each case. That is, the bass signal applied to the power amplifier becomes large, and a heat generation problem of the power amplifier occurs. T
The power amplifier used in the V set has only an output of about 10 W, and there is a concern that the power amplifier may be damaged by heat. In addition, since the bass is constantly boosted, there is a problem that the bass becomes a rough low tone, the sound becomes muffled, and the sound becomes indistinct and hard to hear.

[0006]

In order to solve the above problems, the bass enhancement circuit according to the present invention enhances the bass signal level only at the rising portion of the bass and reproduces the signal, thereby achieving good separation and low power. This is characterized in that the bass is enhanced.

According to the present invention, it is necessary to effectively use the psychological effect due to the feeling of attack of the bass, to enhance the level of only the rising part of the bass, to reproduce the clear bass in an enhanced manner, and to enhance the bass all the time. Since it is no longer necessary, a bass enhancement circuit that can reduce the load on the power amplifier can be provided.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A bass enhancement circuit according to a first aspect of the present invention extracts a bass component from an input audio signal, and enhances and reproduces a bass signal level only in a rising portion of the bass. This makes it possible to realize bass enhancement that requires good power and requires low power.

Next, a bass enhancement circuit according to a second aspect of the present invention is configured such that a signal level is provided at a stage subsequent to an LPF that extracts a bass component from an input audio signal and an amplifier that amplifies the LPF output signal. A low-pitched sound rise detection control circuit comprising a rectifier circuit for rectifying, a differentiating circuit for detecting a rising of the rectified signal level, and an integrating circuit for adjusting a pulse width outputted by the differentiating circuit connected in series; A volume control amplifier (hereinafter abbreviated as VCA) for adjusting the level of the LPF output, and only the pulse width of the rising portion of the bass obtained by the integration circuit of the rising detection control circuit is used to reduce the bass component passed through the LPF. , And can be added to the input audio signal to achieve bass enhancement.

Next, a bass enhancement circuit according to a third aspect of the present invention is the bass enhancement circuit according to the first aspect, wherein a bass component is added downstream of the adder for adding the input audio LR signal. The LPF for extracting the signal, the amplifier for amplifying the LPF output signal, the rectifying circuit for rectifying the signal level, the differentiating circuit for detecting the rise of the rectified signal level, and the pulse output from the differentiating circuit. A low-pitched sound rise detection control circuit having the integrators for adjusting the width connected in series, and a VCA for adjusting the level of the LPF output, wherein the low-pitched sound obtained by the integration circuit of the rise detection control circuit is provided. Only the pulse width at the rising edge of the low frequency component that has passed through the LPF is added to the input audio LR signal, and bass enhancement is performed for two channels of the audio LR. In which it can be realized by Le signal.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment 1) Embodiments of the invention described in claims 1 and 2 of the present invention will be described below with reference to FIGS.
This will be described with reference to FIG.

FIG. 1 is a block diagram of a bass enhancement circuit according to an embodiment of the present invention. In FIG. 1, 1 is an LPF for extracting a bass component, 2 is a bass rise detection control circuit, 3 is an amplifier for amplifying the signal level extracted by the LPF, 4 is a rectifying circuit for rectifying the signal level,
5 is a differentiating circuit for detecting the rise of the rectified signal level, 6 is an integrating circuit for adjusting the pulse width output by the differentiating circuit, 7 is a VCA for adjusting the signal level of the bass component extracted by the LPF, Reference numeral 8 denotes an adder for adding the input audio signal and the bass part.

The operation of the bass enhancement circuit configured as described above will be described. The input audio signal is LP
Only the bass component is extracted by F1 and the signal is amplified by the amplifier 3. The amplified bass component is rectified by the rectifier circuit 4 and its envelope level is output. Next, in order to detect the rising of the envelope, it is differentiated by the differentiating circuit 5 to generate a rising pulse. An integrating circuit 6 is used to appropriately extend the rising pulse width according to the effect. Only when this pulse is at the H level, the bass component extracted by the LPF 1 is passed through the VCA 7 using an appropriately time-expanded pulse.
By adding to the input audio signal, the signal level of only the rising part of the bass component is increased. This will be specifically described as follows.

Normally, a bass is a typical musical instrument for reproducing bass, and it is assumed that the bass is played with a bonbon (referred to as bass running). In this case, one tone of the bass has a waveform of several cycles, there is a blank, and the next tone comes again several cycles. That is, it is the intention of the present invention to increase the signal level by several rising cycles of the waveform of several cycles of one bass sound to enhance the attack feeling.

FIG. 2 shows a time series waveform of each part of the bass enhancement circuit shown in FIG. 1, and is an explanatory diagram when a sine wave is input. That is, when the input audio signal is a low tone only and a waveform (a) is input, the output of the amplifier 3 has a clipped waveform shown in (b). The clipped audio waveform is integrated by the rectifier circuit 4 as shown in (c), and an envelope signal can be extracted. That is, a signal presence / absence section is determined. When this is differentiated by the differentiating circuit 5, a waveform (d) is obtained. (D) The waveform is for detecting a rising portion of a signal from no signal and has a narrow pulse width.
The time width τ is set to a time width in which the effect is obtained by the integration circuit 6, and (e) a waveform is obtained. According to experiments, a time width τ of about several hundred ms is sufficient. Only in the H section of the integration circuit 6, low-frequency components are passed from the VCA and added to the input signal, whereby the signal waveform (f) is finally output. As described above, the bass signal can be enhanced by increasing the signal level of the bass signal only in the rising portion of the bass component.

(Embodiment 2) Next, an embodiment of the invention described in claim 3 of the present invention will be described with reference to FIG. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 3 is a block diagram showing a bass enhancement circuit according to an embodiment of the present invention. In FIG. 3, 9 is an adder for adding the audio LR signal, 1 is an LPF for extracting bass components, 2 is a bass onset detection control circuit, 3 is an amplifier for amplifying the signal level extracted by the LPF,
4 is a rectifier circuit for rectifying the signal level, 5 is a differentiating circuit for detecting the rise of the rectified level, 6 is an integrating circuit for adjusting the pulse width output from the differentiating circuit, and 7 is a low tone extracted by the LPF. V to adjust the signal level of the component
CA and 8 denote the input audio signal and bass component, respectively, as L.
An adder for adding to R.

The operation of the bass enhancement circuit configured as described above will be described. The input signal of the audio LR2 channel is added by the adder 9. Normally, the bass component is an LR in-phase signal at the time of two channels, and thus can be added. LP for extracting bass components from the added signal
Through F1, in the same configuration as in the first embodiment, the rising portion of the bass is detected, only the rising component is passed by the VCA 7 and added to the LR by the adder 8, thereby simplifying the circuit. And the same bass enhancement can be achieved.

In the first and second embodiments, the VCA 7 controls the passage of the low-frequency component only at the rising portion of the low frequency. However, it can be easily realized by a simple electronic switch and a mute circuit. It goes without saying that the amount of addition also needs to be adjusted.

[0020]

As described above, the bass enhancement circuit of the present invention enhances and reproduces the bass signal level only at the rising portion of the bass, thereby reproducing a sharp low-pitched bass. Since no bass enhancement is performed for the entire time, it is possible to provide a bass enhancement circuit that can reduce the load on the power amplifier and minimize heat generation.

If the responsiveness of the speaker is poor,
Although the rising waveform becomes dull and the bass tone becomes poor, if the dulling of the rising waveform is complemented in advance by the bass enhancement circuit of the present invention, bass reproduction by a speaker that is faithful to the original sound waveform can be made.

[Brief description of the drawings]

FIG. 1 is a block diagram of a bass enhancement circuit according to a first embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of each unit in FIG. 1;

FIG. 3 is a block diagram of a bass enhancement circuit according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional bass enhancement circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LPF 2 Bass rise detection control circuit 3 Amplifier 4 Rectifier circuit 5 Differentiator circuit 6 Integrator circuit 7 Volume control amplifier (VCA) 8 Adder 9 Adder

Claims (3)

[Claims] A low tone component is extracted from an input audio signal, and a low tone signal level at only a rising part of the low tone is enhanced to be reproduced, so that a low tone can be enhanced with good separation and low power. A bass enhancement circuit characterized by the following. 2. An LPF for extracting a low-frequency component of an input audio signal, a rectifier circuit for rectifying a signal level after an amplifier for amplifying the LPF output signal, and detecting a rise of the rectified signal level. A differential circuit, and a bass rising detection control circuit in which an integrating circuit for adjusting a pulse width output by the differential circuit is connected in series, and a volume control amplifier for adjusting a level of the LPF output, A bass enhancement circuit that adds a bass component that has passed through the LPF to an input audio signal only for a pulse width of a bass rising portion obtained by an integration circuit of a rising detection control circuit to enhance bass. 3. An LPF for extracting a low-frequency component, which is provided at a stage subsequent to an adder for adding an input audio LR signal,
The amplifier for amplifying an output signal, the rectifying circuit for rectifying a signal level, the differentiating circuit for detecting a rise of the rectified signal level, and the integrating circuit for adjusting a pulse width output by the differentiating circuit. A bass rising detection control circuit connected in series;
The volume control amplifier for adjusting the level of the PF output, and only the pulse width of the rising portion of the bass obtained by the integration circuit of the rising detection control circuit, the bass component passed through the LPF, and the input audio LR signal To increase the bass sound.