JPH067667Y2 - Audio playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an audio reproducing apparatus, and more particularly to improvement of an amplifier for driving a small speaker system.

[Prior Art] A conventional audio reproducing apparatus includes at least a music signal generation source such as a record player, a tuner, and a tape recorder, and an amplifier for amplifying a signal from the generation source to a level required to drive a speaker system. , A speaker system such as a full-range speaker system composed of a single speaker (full-range speaker) or a multi-way speaker system in which a plurality of speakers having different reproduction frequency bands are combined.

In particular, in a compact audio reproducing device, from the viewpoint of product price and arrangement space, an amplifier having an output of about 10 to 40 W, a two-way speaker system including a full-range type or low-frequency speaker and a high-frequency speaker is combined. Audio playback devices are often used.

[Problems to be solved by the invention] In such a small audio reproducing apparatus, the internal volume of the speaker box is inevitably small due to restrictions on the arrangement space, and it is difficult to adopt a large-diameter speaker. , Dissatisfaction with bass reproduction ability.

Generally, as a means for improving the bass reproduction capability under the above conditions, the vibration system mass of the speaker is increased in order to lower the minimum resonance frequency of the bass reproduction speaker, but the efficiency of the bass reproduction speaker is increased. However, in order to obtain the balance of the speaker system as a whole, it is necessary to limit the input of the speaker for middle and high frequencies, and the efficiency of the speaker system as a whole decreases.

On the other hand, in the small audio reproducing apparatus, as described above, since the output of the amplifier is limited, it is advantageous that the efficiency of the speaker system is as high as possible.

As a means for solving this point, a so-called low boost circuit or a tone control circuit is added to the amplifier to increase the amplification degree of only the low tone signal.

However, in an amplifier to which a circuit of this kind is added, in the small audio reproducing apparatus in which the output of the amplifier is limited as described above, the signal is clipped while the input level is lower by the boosted amount.

Therefore, when the bass signal and the treble signal are mixed, the treble signal is intermodulated by the bass signal, which causes deterioration of the sound quality.

Further, even in the case of only the low-pitched sound signal, there is a problem that it is reproduced from the mid-range and high-pitched speaker due to the generation of the harmonics due to the clip, which causes the deterioration of the sound quality.

[Means for Solving the Problem] The present invention connects the input terminal to which an input signal is applied and the input terminal by paying attention to the fact that the user does not frequently replace the speaker apparatus with another speaker apparatus in the small speaker apparatus. And a filter circuit having a low-pass characteristic and having a gain of 1 or more in the pass band connected to the input terminal and the output terminal of the filter circuit, and the input terminal. A subtraction circuit, a second amplification circuit connected to the output end of the subtraction circuit, a first output terminal connected to the output end of the first amplification circuit, and a second output terminal connected to the output end of the second amplification circuit. A speaker device having an amplifier, a low-pitched sound reproducing speaker, and a high-pitched sound reproducing speaker, wherein one input end of the high-pitched sound reproducing speaker is connected to the first output terminal and the other input end is grounded. Are respectively connected, which is the audio reproduction apparatus to one input terminal of the low-frequency sound reproducing speaker said first output terminal and the other input terminal respectively connected to said second output terminal.

[Embodiment] The present invention will be described with reference to the following embodiments.
In FIG. 1, 1 is L of a monaural signal or a stereo signal.
It is an input terminal to which a channel or R channel signal is applied, and one of the terminals 1a is the first amplifier circuit 2a.
In addition, the output of the first amplifier circuit 2a is connected to the first output terminal 3a.

The input terminal 1a is a subtraction circuit 4 and a filter circuit 5.
The output of the filter circuit 5 is input to the subtraction circuit 4 and is subtracted from the signal applied to the input terminal 1a.

The output of the subtraction circuit 4 is input to the second amplification circuit 2b, and the output of the second amplification circuit 2b is connected to the second output terminal 3b.

Further, the first output terminal 3a is connected to the high-pitched sound reproducing speaker 6a via the network circuit 6, and the first output terminal 3a
A bass reproduction speaker 6b is connected between a and the second output terminal 3b.

Further, the other input terminal 1b and the speaker 6a for high-pitched sound reproduction.
The other terminals of are connected to the ground.

In such a configuration, assuming that the signal level applied to the input terminal 1 is Es, the output v1 of the amplifier circuit 2a is v1 =
A · Es (where A is the amplification factor of the amplification circuits 2a and 2b) and the transfer function of the filter circuit 5 is T, the output of the subtraction circuit 4 is (1-T) Es, and the output v2 of the amplification circuit 2b is v2 = A.
It is represented by (1-T) Es.

Therefore, the input level vo input to the bass reproduction speaker 6b is represented by vo = v1-v2 = A · T · Es.

If a low-pass filter or a low-frequency band-pass filter having a pass band gain of 1 or more (for example, 2) is used as T, the low-frequency reproduction speaker 6b has a low-frequency signal twice as high as that of the high-frequency reproduction speaker 6a. Is applied, the efficiency of the speaker for low-pitched sound reproduction can be reduced by that much, the minimum resonance frequency can be lowered, and the low-frequency reproduction capability can be improved.

That is, the full-band signal (Es) applied to the input terminal is amplified (A · Es) and output to the amplifier circuit 2a.
On the other hand, the subtraction circuit 4 receives the full band signal (Es) and the low frequency signal (2Es) output through the low pass filter. Therefore, in the subtraction circuit 4, the difference between the full-band signal and the low-frequency signal whose amplitude is doubled is obtained, so that the output has the same phase as the full-band signal and the low-frequency signal (-Es) having the same amplitude as the above-mentioned signal. It includes a high frequency band signal component (a high frequency band signal component excluding the low frequency band signal component) having the same phase and the same amplitude as the entire band signal component. The signal is an amplifier 2b
Is amplified by and is input to the minus side of the bass reproduction speaker 6b as a low-frequency signal component (-A-Es) and a high-frequency signal component (A-Es). On the other hand, the bass reproduction speaker 6
Since the full-band signal (A · Es) is input to the positive terminal of b, the low-frequency signal components are in-phase input, and the amplitude thereof is (2A · Es). On the other hand, the high frequency signal components become mutually opposite phase inputs and the signal components are canceled, so that the bass reproduction speaker 6b is driven only by the pass band signal component of the low pass filter.

Such a filter circuit used in the audio reproducing apparatus of the present invention has the characteristics shown in FIG. A low-pass filter circuit having a 6 dB / oct falling characteristic represented by the transfer function of, such as the characteristic shown in FIG. 2-b, A low-pass filter circuit having a rising and falling characteristic of 6 dB / oct represented by the transfer function of, such as the characteristic shown in Fig. 2-c, A low-pass filter circuit having a falling characteristic of 12 dB / oct represented by the transfer function of, such as the characteristic shown in FIG. 2-d, 6dB / oct rise characteristic expressed by transfer function of 12dB / oct
A bandpass filter circuit having a falling characteristic of
e characteristics such as 12dB / oct rise characteristic expressed by transfer function of 6dB / oct
A bandpass filter circuit having a falling characteristic of
The characteristics shown in Fig. f, A bandpass filter circuit having a rising characteristic and a falling characteristic of 12 dB / oct represented by the transfer function of can be used.

FIG. 3 shows an amplifier using a bandpass filter capable of obtaining the characteristics shown in FIG. 2-e. The output level v1 of the amplifier circuit 2a, the input level v3 of the filter circuit 5, and the subtraction circuit when the input level is Es. 4 output level v
4, the output level v2 of the amplifier circuit 2b is Therefore, the signal level vo applied to the bass reproduction speaker is It is represented by.

Further, by using the variable gain type filter circuit illustrated in FIGS. 4-a and 4-b, ζ1 or ζ1 and ω1 are changed as shown in FIGS. 5-a and 5-b. It was possible to control the level of the lower frequency band by lowering the low frequency resonance frequency of the speaker system or by increasing the level of the frequency band slightly lower than the low frequency resonance frequency.

[Effect of the Invention] As described above, according to the present invention, for the purpose of improving the low-frequency reproduction capability, a speaker system designed to have a low low-frequency resonance frequency is connected by, for example, increasing the mass of the vibration system. Even if it is done, the input level of the bass reproduction speaker can be made higher than that of the treble speaker, so that the bass reproduction capability could be improved without impairing the overall balance of the speaker system. .

Further, unlike the conventional low boost circuit, in this invention, only the amplifier circuit 2b performs the low boost operation.
Since the amplification circuit system to which the high-pitched sound speaker 6a is connected has a flat characteristic, the low-boost action does not have any effect on the amplification circuit 2a. Since the characteristics of the high-pitched sound reproducing speaker are not deteriorated, there is an advantage that the deterioration of the high-pitched sound can be prevented.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIGS.
FIG. f is a frequency characteristic diagram of a filter embodiment used in the present invention, FIG. 3 is a filter circuit diagram which can obtain the characteristic of FIG. 2-e, FIG. 4-a and FIG. The filter circuit diagram, FIG. 5-a and FIG.
FIG. 4 is a frequency characteristic diagram of the present invention using the filters of FIGS. 4a and 4b. 1 is an input terminal, 2a is a first amplifier circuit, 5 is a filter circuit, 4 is a subtraction circuit, 2b is a second amplifier circuit, 3a is a first output terminal, 3b is a second output terminal, 6a is a speaker for high-pitched sound reproduction, 6b is a speaker for low-pitched sound reproduction.

Claims (2)

[Scope of utility model registration request] 1. A low-pass characteristic which is connected to an input terminal (1) to which an input signal is applied, a first amplifier circuit (2a) connected to the input terminal (1) and the input terminal (1). And a subtraction circuit (4) connected to the output terminal of the filter circuit (5) and the input terminal (1) having a gain of 1 or more in the pass band, and the subtraction circuit (4). 4) A second amplifier circuit (2b) connected to the output terminal
And an amplifier having a first output terminal (3a) connected to the output terminal of the first amplifier circuit (2a) and a second output terminal (3b) connected to the output terminal of the second amplifier circuit (2b), Bass reproduction speaker (6b) and treble reproduction speaker (6
a) is provided, and one input end of the speaker (6a) for high-pitched sound reproduction is connected to the first output terminal (3a), and the other input end thereof is connected to the ground, and the low-pitched sound reproduction is performed. Speaker (6b) has one input end connected to the first output terminal (3a) and the other input end connected to the second output terminal (3a).
An audio reproducing apparatus characterized in that each is connected to an output terminal (3b). 2. The audio reproducing apparatus according to claim 1, wherein the filter circuit (5) is a variable gain type filter circuit.