JPH02256400A - Audio signal reproducing device - Google Patents

Abstract

PURPOSE:To obtain a unique surround effect by using 1st and 2nd low frequency signals with a prescribed phase difference so as to amplitude-modulate input R and L channel signals and superimposing the modulated signal onto the input R-channel and L-channel signals so as to use the result to an input signal to R-channel and L-channel speakers. CONSTITUTION:R and L channel signals fed via input terminals 11, 12 are fed to variable gain amplifiers 13, 14, the gain of the variable gain amplifiers 13, 14 is controlled in response to the low frequency signal fed via the input terminal 15. The outputs of the variable gain amplifiers 13, 14 are superimposed on an adder 17 and the result is an amplitude modulation wave signal, which is one input to a subtractor 20 and an adder 21 respectively. The R and L channel signals are fed to other inputs of the subtractor 20 and the adder 21. The outputs of the subtractor 20 and the adder 21 are fed to speakers R, L, from which a reproducing sound is obtained. Thus, a unique surround effect is obtained.

Description

TECHNICAL FIELD The present invention relates to an audio signal reproducing device, and more particularly to an audio signal reproducing device that obtains a special surround effect.

BACKGROUND ART As shown in FIG. 3, an audio signal reproducing apparatus is known in which four speakers are arranged around a listener to form a special sound field. In an audio signal reproducing device, R and L signals obtained from a stereo demodulation circuit (not shown)
Channel signals are received by an input terminal 1.2, amplified by a drive circuit 3.4, and supplied to the front right speaker FR and the front left speaker FL, respectively. Further, the R and L channel signals are delayed by delay circuits 5 and 6 which produce appropriate delays and then supplied to a drive circuit 7.8, which drives the rear right and rear left speakers RR and RL.

The output terminals of the drive circuit 7.8 are connected to both ends of the coil of the speaker RR, and are connected to both ends of the coil of the speaker RL so as to be in opposite phase to the coil of the speaker RR.

According to the audio signal reproducing apparatus having such a configuration, each of the R signals is output from the speakers FR, FL, RR, and RL.

The L signal, (LR) signal, and (RL) signal are reproduced and reach the listener 9. As a result, the listener 9 perceives a special surround effect due to the level change of the R signal and the L signal.

However, such an audio signal reproducing device uses four speakers and is not only expensive but also requires a considerable amount of space.

SUMMARY OF THE INVENTION The object of the present invention is to use two speakers at low cost;
Moreover, it is an object of the present invention to provide an audio signal reproducing device that obtains a surround effect in which the sense of expansion of the sound field changes periodically.

In the audio signal reproducing device according to the present invention, input R is input by first and second low frequency signals having a predetermined phase difference.
After each of the channel signal and L channel signal is amplitude modulated, this is superimposed on the input R channel and 4 channel signals to be input signals to the R side and L side speakers.

Example Examples of the present invention will be described below.

FIG. 1 shows an audio signal reproducing apparatus according to an embodiment of the present invention, in which an R channel signal and an L channel signal are supplied to input terminals 11 and 12.

The supplied R and L channel signals are sent to variable gain amplifier 1.
Provided on 3.14. The variable gain amplifier 13.14 is
It may also be a variable attenuator. Variable gain amplifier 13. ．． 1
The gain of 4 (attenuation ff1 in case of attenuator) is input terminal 15
A low frequency signal preferably of angular frequency ωC supplied via
It is controlled in accordance with a sine wave signal (sinωCt), that is, the first low frequency signal A, and a phase shift of this signal A that has passed through the 90° phase shifter 16, that is, the second low frequency signal B. The outputs of the variable gain amplifiers 13 and 14 are added by an adder 17 acting as a superimposing means to become an amplitude modulated wave signal C, which is sent to one of each of a subtracter 20 and an adder 21 via a delay circuit 18 and an attenuator 19. becomes the input. Subtractor 20 and adder 2
1 is supplied with R and L channel signals R9L via input terminals 11.12. The respective outputs of the subtracter 20 and the adder 21 are supplied to speakers R and L through a power amplifier (not shown) to drive these speakers to obtain reproduced sound.

Note that the delay circuit 18 and the attenuator 19 may be omitted depending on the case.

In the audio signal reproducing device described above, if the R and L channel signals R and L are flat, the first low frequency signal A
And when the waveform of the second low frequency signal B changes as shown in FIG. 2 (a), the waveform of the amplitude modulated wave signal C changes as shown in FIG. 2 (b) for the R component and the L component. becomes.

That is, the amplitude modulated wave signal C changes (
-L) component, (R-L) component, (R) component, (R+L)
Since the components... are output, the R channel signal and the L channel signal are output so as to be swung left and right. Therefore, this signal C is delayed by the delay circuit 18, and the attenuator 1
9 and are added to and subtracted from the original R channel signal and L channel signal, respectively, so that the stereo surround effect is temporally converted to a low frequency signal (for example, a sine wave signal (
snωat)), a new stereo surround effect can be obtained.

Note that the angular frequency ωC, that is, the frequencies of the first and second low frequency signals can be appropriately selected within a range of, for example, several tens of cycles. The frequency may be determined in advance and fixed, but it can also be made variable by manual operation.

As is clear from the detailed description of the invention, according to the audio signal reproducing device according to the present invention, it is possible to periodically change the sense of expansion of the sound field using two speakers, thereby obtaining a unique surround effect. It is possible.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing an embodiment of the present invention, Figure 2 (a)
, (b) are waveform diagrams showing waveform changes of the first and second low frequency signals and waveform changes of the amplitude modulated wave signal in the apparatus of FIG. 1, and FIG. 3 is a circuit diagram showing a conventional example. Explanation of symbols of main parts 13.14...Variable gain amplifier 19...
・Attenuator 20...Subtractor 21...Adder Applicant: Pioneer Corporation

Claims (4)

[Claims] (1) a first amplification (attenuation) means for amplifying (attenuating) a right channel signal by an amplification factor (attenuation factor) that changes according to the level of the first low frequency signal; a second amplification (attenuation) means for amplifying (attenuation) the left channel signal by an amplification factor (attenuation factor) that changes according to the level of the second low frequency signal having a phase difference; and the first and second amplification (attenuation) means. a superimposing means for adding an alternating current component in the output of the means; a subtracting means for subtracting the output of the superimposing means from the right or left channel signal; and an adding means for adding the output of the adding means to the right or left channel signal. and right and left speakers that convert the outputs of the subtracting means and the adding means into acoustic energy. (2) The audio signal reproducing apparatus according to claim 1, wherein the predetermined phase shift difference is a phase difference of 90 degrees. (3) The audio signal reproducing apparatus according to claim 1, further comprising a delay means for delaying the output of the superimposing means. (4) The audio signal reproducing apparatus according to claim 1 or 2, further comprising a level adjusting means for adjusting the level of the output of the superimposing means.