JPH04273700A - Acoustic equipment - Google Patents

Abstract

PURPOSE:To close up an echo acoustic component by providing an amplifier having a noninverting amplifier input and an inverting amplier input terminal to left and right channels and connecting an HPF between the inverting input terminal and an output terminal as specified. CONSTITUTION:A signal of other channel at a lower level than a level at a noninverting amplifier input terminal (+) of an amplifier 1 is inputted to an inverting amplifier input terminal (-) by the action of an HPF 3. Thus, an amplifier output in the case of noninverting and same level input for left and right channels at medium and high frequencies is lower than that at sound field expansion function inoperating state. Moreover, when the signal is inputted only to one channel, the output of the amplifier 1 for the channel is increased by the sound field magnification function inoperation state and an output of the amplifier 1 of the opposite channel appears at an opposite phase, and when both the channels are checked as a whole, the level is increased more than that at the inoperation state in the operation of the sound field magnification function. An LPF 2 prevents it that the entire frequency characteristic at medium and high frequencies is boosted thereby making the frequency characteristic flat.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio device having a stereo reproduction device with a sound field expansion function.

0002

[Prior Art] In recent years, stereo playback has become common in audio equipment, but there is a growing trend toward multi-functionality, such as improving the sound quality of audio equipment dedicated to small headphones, and adding sound field expansion functions such as surround sound. The number of products equipped with it is increasing.

An example of a conventional audio device will be described below with reference to the drawings. FIG. 2 is a circuit block diagram showing only the sound field expansion function section of a conventional audio device. In FIG. 2, 5 is an input terminal of the sound field expansion function section, 6 is an output terminal, 7 is a subtracter that obtains a difference signal from the left and right channels, 8 is a delay circuit, 9 is an in-phase amplifier, 10 is an inverting amplifier, and 11 is an inverting amplifier. It is an adder. The delay time of the delay circuit 8 is set to several tens of microseconds. Here, if the left channel signal is L and the right channel signal is R, the output of the subtracter 7 is RL, and the output of the delay circuit 8 is Δ(RL). Therefore, at output terminal 6, the L channel side is (L - ΔL) + ΔR, and the R channel side is (R - ΔR) +
It becomes ΔL. That is, it attempts to obtain a sound field expansion effect by creating simulated sound reflected from the walls of a hall or room (ΔR, ΔL) and mixing it into the left and right channels.

0004

[Problems to be Solved by the Invention] However, with the conventional sound equipment as described above, when played through speakers placed in the front, a sound field expansion effect can be obtained, but when played through headphones, the sound field is expanded. Since the sound output from the speakers is input directly to the left and right ears without going through the space, it is not possible to obtain a sound field expansion effect. In addition, since the left and right difference signal is a signal centered on mid- and high-frequency components that do not include bass components or vocals located at the center of the music source, there is a problem that the mid-high frequencies are emphasized when the sound field expansion function is activated. It had a point.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has an object of providing an audio device that can obtain a sound field expansion effect without changing the frequency characteristics even when reproduced through headphones.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the audio device of the present invention has a stereo reproduction device, in which left and right amplifiers each having both an in-phase amplification input terminal and an inverted amplification input terminal are connected to each other. channel, and has a low-pass filter in front of each in-phase amplification input terminal, and a high-pass filter connected to the output side of each amplifier, and the output side of the high-pass filter is connected to the inverse of the other channels. It is equipped with a sound field enlarging means configured to be connected to an amplification input terminal.

[0007]

[Operation] With the above-described configuration, the present invention uses the operation of the high-pass filter to
It will be input to the inverting amplification input terminal at a level lower than the level of the common-mode amplification input terminal, and although the output will be low when a signal localized to the center is input, the output of a signal input only to one channel will be It will be enhanced. Therefore, by the operation of the sound field enlarging means, the reverberant sound components in the music source whose localization is random are brought into close focus, and the sound field enlarging effect can be obtained. This can be achieved without changing the characteristics.

[0008]

[Example] Hereinafter, an example of the acoustic device of the present invention will be described.
This will be explained in detail with reference to the drawings.

FIG. 1 shows a block diagram of a sound field enlarging means portion of an acoustic device according to an embodiment of the present invention. In the figure, 1 is an amplifier (power amplifier) that directly drives the headphone speaker, and the common-mode amplification input terminal (+)
and an inverting amplification input terminal (-). 2 is a low-pass filter placed before the amplifier 1, and its output is connected to the in-phase amplification input terminal (+). A high-pass filter 3 is connected between the output side of the amplifier 1 and the inverting amplification input terminals (-) of the other channels.

Reference numeral 4 denotes a control switch means for switching the operation/non-operation of the sound field expansion means constructed as described above, and controls the operating state of the low-pass filter 2 and the high-pass filter 3 and the gain control of the amplifier 1. It is. That is, depending on the control, operation or non-operation of sound field expansion is selected. In addition, 5 is the input terminal of the music source,
6 is an output terminal connected to a headphone speaker.

The amplifier 1 has a gain of about 23 dB when the sound field expansion function means is not in operation, and is configured to increase the gain by about 6 dB by controlling the switch means 4 when it is in operation. Low pass filter 2 is
It is configured to operate as a filter with a turnover of several hundred Hz during sound field expansion operation and attenuate approximately 6 dB in the middle and high frequencies, and to pass through when not in operation. In addition, the high-pass filter 3 has a turnover of several tens of Hz when the sound field expansion means is in operation, and operates as a filter with an attenuation of about 30 dB in the mid-high range, and when it is not in operation, the circuit is open and the signal is completely blocked. It is configured to have a specific shape.

The operation of the acoustic device configured as described above will be explained below. First, when the sound field expansion means is not operating, the amplifier 1 is controlled by the switch means 4.
It is equivalent to a circuit block diagram with only the following parts left, and operates as a normal stereo playback circuit without a sound field expansion function.

Next, the operation of the sound field enlarging means will be explained. By operating the high-pass filter 3, the signals of other channels are transmitted to the inverted amplification input terminal (- ). As a result, the output of the amplifier 1 due to the input of a signal localized to the center in the middle and high frequency range of several tens of Hz or more (signals with the same phase and the same level in the left and right channels) becomes lower than when the sound field expansion function is not operating. In addition, in the case of a signal input to only one channel, the output of amplifier 1 on the side where the signal is input is higher than when the sound field expansion function is not activated, and the output of amplifier 1 on the opposite channel is in reverse phase. When considering both channels as a total, when the sound field expansion function is activated, the level will be even higher than when it is not activated. Further, when signals of the same level and opposite phases are input to the left and right channels, the output level of the amplifier 1 will be higher for both channels when the sound field expansion function is activated than when the sound field expansion function is not activated.

In other words, the reason why the output of the amplifier 1 becomes lower than when the sound field expansion function is not activated is when the input signals are in phase and at the same level (
center localization signal). Therefore, the overall level of reverberant sound whose localization is random is increased. On the other hand, the gain of the amplifier 1 is increased to compensate for the amount of attenuation of the center localized component in the music source to some extent. Therefore, the reverberant sound enhanced by the above-mentioned effect is further enhanced.

[0015] Although the reverberation sound could be brought into close-up through the above-described operation, if left as is, the overall frequency characteristic would be one in which the middle and high ranges were boosted. Therefore, in order to compensate for this, the low-pass filter 2 is operated to flatten the frequency characteristics. Note that the turnover frequency of each filter was determined by repeatedly listening to music sources so that the frequency characteristics would be flat. However, in order to obtain a high sound field expansion effect, the turnover frequency of the high-pass filter 3 needs to be as low as possible. In addition, the amount of attenuation of each filter is closely related to the sound field expansion effect, and it is important to maximize the sound field expansion effect and improve the total volume and frequency characteristics when the sound field expansion function is activated and deactivated. This decision was made with the aim of suppressing changes as much as possible.

As described above, according to this embodiment, only the reverberant sound can be brought into close-up without changing the frequency characteristics of the music source, and a sound field expansion effect can be obtained.

[0017]

[Effects of the Invention] As described above, the present invention enables input to the inverting amplification input terminal at a level lower than the level of the common-mode amplification input terminal in the mid-to-high frequency range of several tens of Hz or more by the operation of the high-pass filter. Therefore, although the output will be low when a signal localized to the center is input, the output of a signal input only to one channel will be increased. Therefore, by the operation of the sound field expansion means,
Reverberant sound components in music sources with random localization are brought into close-up, and the sound field expansion effect can be obtained without changing the frequency characteristics, so even when played through headphones, the frequency characteristics do not change. This is a very effective invention as it can produce a sound field expansion effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an audio device according to an embodiment of the present invention.

[Figure 2] Block diagram showing an example of a conventional audio device

[Explanation of symbols]

1 Amplifier 2 Low pass filter 3 High pass filter 4 Control switch means + Common mode amplification input terminal − Inverting amplification input terminal

Claims (3)

[Claims] Claim 1: An audio device having a stereo reproduction device, which has amplifiers provided with both an in-phase amplification input terminal and an inverted amplification input terminal in left and right channels, and a low-pass filter in front of each in-phase amplification input terminal. With,
It is characterized by comprising a high-pass filter connected to the output side of each of the amplifiers, and sound field expansion means configured to connect the output sides of the high-pass filters to the inverting amplification input terminals of the other channels. sound equipment. 2. According to claim 1, further comprising a control switch means capable of switching between reproduction by operating the sound field enlarging means and normal stereo reproduction by non-operating the sound field enlarging means; An acoustic device characterized in that it is configured to control the operation or non-operation of a low-pass filter and a high-pass filter, and at the same time control the gain of the amplifier. 3. The audio device according to claim 1, wherein the audio device is constructed using a power amplifier for driving a speaker, which is included in a normal stereo playback device, as the amplifier.