JPH0515000A - Bass boost circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] In the bass boost circuit of the stereo audio output device in which the Lch and RCH speakers 6 are driven by the L and Rch main amplifiers 3 and 4, respectively, a superwoofer band (bass component) is set. The cost will be reduced by enabling playback without a dedicated amplifier and speaker. [Structure] A bass component extraction circuit 7 for increasing or decreasing the low-frequency level of L + R components of L and Rch audio signals input from terminals 1 and 2 is provided, and an electric circuit connecting the terminals 1 and 2 and main amplifiers 3 and 4 is provided. Then, adder circuits 21 and 22 for adding the L and Rch audio signals input from the terminals 1 and 2 and the output signal of the bass component extraction circuit 7 are inserted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereo sound reproducing device such as a stereo and a television, and more particularly to a bass enhancing circuit.

[0002]

2. Description of the Related Art Conventionally, for example, a 3D system as shown in FIG. 5 has been adopted as a bass reproduction method of stereo sound.
In FIG. 5, 1 is a terminal to which a left channel (Lch) audio signal is input, and 2 is a terminal to which a right channel (Rch) audio signal is input. The L and Rch audio signals input from these terminals 1 and 2 are Lc by the main amplifiers 3 and 4.
Sound is produced from the h speaker 5 and the Rch speaker 6. Reference numeral 7 denotes a bass component extraction circuit, which outputs L + from the L and Rch signals.
It is composed of a detection circuit 8 for detecting the R component, a low-pass filter 9 for passing only the reduction of the L + R component, and an adjusting unit (comprising an amplifier and attenuator) 10 for increasing / decreasing the level of the low tone. The low tone output from the low tone component extraction circuit 7 is sounded from the super woofer 12 by a dedicated super woofer amplifier 11. With such a circuit configuration, the bass level can be adjusted independently of the L and R levels.

The frequency characteristic of the above circuit is represented by a curve d of L and R signal characteristics and curves e, f and g of super woofer characteristics as shown in FIG. In FIG. 6, the super woofer is moved from the MAX curve e to the M by the adjusting unit 10.
It is increased or decreased within the range of the IN curve g. Further, the L and R characteristics are cut to be reduced around 100 Hz as shown by the curve d so that the super woofer does not interfere with the L and R speakers.

[0004]

In the conventional 3D system as shown in the circuit of FIG. 5, a dedicated superwoofer drive amplifier 11 and superwoofer 12 are required, resulting in a large number of parts. Further, since the frequency characteristics of L and R are reduced and cut, there is a drawback that the low frequency component (super woofer band) is cut when listening through headphones.

The present invention has been made in view of the above points, and an object thereof is to eliminate the need for a drive amplifier and a speaker dedicated to a superwoofer, simplify the circuit to reduce the cost, and reproduce heavy bass even with headphones. The present invention is to provide a bass enhancing circuit.

[0006]

According to the present invention, there is provided (1) a bass component extraction circuit for detecting an L + R component from each of L and R channel audio signals and adjusting a signal level of the L + R component in a low frequency region. And an adder circuit for adding the respective audio signals of the L and R channels and the output signal of the bass component extraction circuit, and driving the speaker by the output of the adder circuit, (2) In an audio circuit equipped with a headphone terminal that is connected between the L and R channel drive amplifier and the L and R channel speaker and switches the speaker input signal to the headphone side when the headphone jack is inserted, and a superwoofer drive amplifier and superwoofer. ,
A bass component extraction circuit that detects an L + R component from each of the L and R channel audio signals and adjusts the signal level in the low frequency region of the L + R component, and each of the L and R channel audio signals and the bass component extraction circuit. And an output circuit for adding each of the output signals and the bass component extraction circuit is closed when the headphone jack is not inserted, and the bass component extraction circuit is closed when the headphone jack is inserted. And a changeover switch circuit for closing an electric path connecting the adding circuit.

[0007]

(1) The bass component extraction circuit adjusts the level of the L + R component in the low frequency region of the audio signals of the L and R channels. The output signal of the bass component extraction circuit is added to the audio signals of the L and R channels by the addition circuit. Therefore, when the speaker is driven by the output of the adding circuit, not only the L and R channel sounds but also the low tone is reproduced by the L and R channel speakers. Therefore, the amplifier and speaker dedicated to the super woofer can be eliminated.

Further, since the L and R channel signals and the bass component extraction circuit are added, as compared with the conventional bass woofer-less system for enhancing bass, for example, the tone control BASS MAX system,
The bass can be enhanced without adversely affecting the mid-bottom region (human voice, etc.).

(2) When no headphones are inserted in the headphone jack, the L and R channel speakers are driven by the outputs of the L and R channel drive amplifiers, respectively, and the super woofer is activated by the output of the bass component extraction circuit. Driven. When headphones are inserted into the headphone jack, the changeover switch circuit is switched and the output of the bass component extraction circuit is added to the L and R channel signals by the addition circuit, and the L and R channel speakers and the superwoofer are electrically connected. To be separated. Therefore, the output signal of the adder circuit in which the bass components of the L and R channels are increased / decreased is supplied to the headphones via the headphone terminal. This allows you to hear the low tones that would normally come out of a superwoofer through headphones.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention of claim 1 will be described below with reference to the drawings. 1, the same parts as those in FIG. 5 are designated by the same reference numerals. 1 is different from FIG. 5 in that the super woofer amplifier 11 and the super woofer 1 are different.
2 is removed, and addition circuits 21 and 2 for adding the output of the bass component extraction circuit 7 and the L and Rch audio signals to the electric path connecting the terminals 1 and 2 and the main amplifiers 3 and 4, respectively.
2 is inserted, and the other parts are configured the same as in FIG.

In the circuit configured as described above, L
The output (bass component) of the bass component extraction circuit 7 in which the level of the low frequency band of the + R component is increased / decreased is added to the L and Rch audio signals in addition circuits 21 and 22, respectively. Adder circuit 2
The output signals of 1 and 22 are Lch by the main amplifiers 3 and 4.
The sound is produced by the speaker 5 and the Rch speaker 6.

The frequency characteristic of this circuit is as shown in FIG. 2, and is adjusted by the adjusting unit 10 in the range from the curve c at MAX to the curve a at MIN with respect to the original L and R characteristic curve a at about 100 Hz or less. It Generally, in the case of a system without a superwoofer, the bass enhancement method is based on the tone control BASS MAX, but its characteristics are as shown by the curve d in FIG. 3, which is 100 to 1 KHz in the shaded area compared to the curve c. The low and mid frequencies in the middle also rise, making the human voice unnatural. In the present proposal, as can be seen from the curve c, the bass can be enhanced without affecting the human voice.

Next, an embodiment of the invention of claim 2 will be described with reference to FIG. 4, the same parts as those in FIG. 5 are designated by the same reference numerals. 4 is different from FIG. 5 between the main amplifiers 3 and 4 and the L and Rch speakers 5 and 6.
The headphone terminal 31 is connected and the terminals 1 and 2 are connected.
The adder circuits 21 and 22 for adding the output of the bass component extraction circuit 7 and the L and Rch audio signals, respectively, are inserted in the electric path connecting the main amplifiers 3 and 4 with the bass component extraction circuit 7.
A changeover switch circuit 32, which is controlled to change depending on the presence or absence of headphones, is inserted in an electric path connecting the super woofer amplifier 11 and the super woofer amplifier 11, and the other parts are configured the same as in FIG.

In the circuit configured as described above, when the headphones are not inserted, the terminal piece of the headphone terminal 31 is open, the control signal to the changeover switch circuit 32 is at the high level, and the bass component is extracted. The output of the circuit 7 is input to the drive amplifier 11 of the superwoofer amplifier 12. Headphones are headphone terminal 3
When inserted in 1, the terminal piece is pushed upward and the terminal piece moves upward to connect with the terminal piece. Therefore, the control signal of the terminal piece is grounded via the speaker 5 and becomes a low level, and the changeover switch circuit 32 is switched to output the output of the bass component extraction circuit 7 to the addition circuits 21 and 22.
Signals are output from the amplifiers 3 and 4 to the headphones through the resistors R _L and R _R and from the terminal pieces.

As described above, since the changeover switch circuit 32 is changed over when the headphone jack is inserted, the low-pitched sound component (super woofer band) can also be heard through the headphones.

[0016]

As described above, according to the first aspect of the present invention, since the bass component extraction output is added to the L channel and the R channel, the super woofer and its drive amplifier can be deleted, and the circuit becomes simple. The cost can be reduced. In addition, the bass can be enhanced without affecting the human voice as compared with the normal tone control. According to the invention of claim 2, the bass component extraction output is switched depending on the presence or absence of headphones, so that the bass enhanced signal can be heard by the headphones.

[Brief description of drawings]

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

FIG. 2 is a frequency-level characteristic diagram showing frequency characteristics of the circuit of FIG.

3 is a frequency-level characteristic diagram comparing the conventional tone control characteristic and the frequency characteristic of the circuit of FIG.

FIG. 4 is a block diagram showing an embodiment of the invention of claim 2;

FIG. 5 is a block diagram showing an example of a conventional bass enhancement circuit.

FIG. 6 is a frequency-level characteristic diagram showing frequency characteristics of the circuit of FIG.

[Explanation of symbols]

1, 2 ... Audio signal input terminals 3, 4 ... Main amplifier 5 ... Lch speaker 6 ... Rch speaker 7 ... Bass component extraction circuit 8 ... L + R detection circuit 9 ... Low pass filter 10 ... Adjustment unit 11 ... Super woofer amplifier 12 ... Super woofers 21, 22 ... Adder circuit 31 ... Headphone terminal 32 ... Changeover switch circuit

Claims (2)

[Claims] 1. L + from audio signals of L and R channels
A bass component extraction circuit that detects the R component and adjusts the signal level in the low frequency region of the L + R component, and an addition that adds each of the L and R channel audio signals and the output signal of the bass component extraction circuit A bass boosting circuit, characterized in that the speaker is driven by the output of the adding circuit. 2. A headphone terminal connected between the L and R channel drive amplifiers and the L and R channel speakers to switch the speaker input signal to the headphone side when the headphone jack is inserted, and a superwoofer drive amplifier and a superwoofer. In a provided audio circuit, a bass component extraction circuit that detects an L + R component from each of the L and R channel audio signals and adjusts the signal level in the low frequency region of the L + R component, and each of the L and R channel audio signals And an output signal of the bass component extraction circuit, and an addition circuit for adding the output signal of the bass component extraction circuit, closing the electric path connecting the bass component extraction circuit and the superwoofer drive amplifier when the headphone jack is not inserted, and inserting the headphone jack. Sometimes the low-frequency component extraction circuit and the addition circuit are connected to each other. A bass boost circuit, comprising: a changeover switch circuit for closing a path.