JP2018007221A - Speaker system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which, since most compact speaker systems used in an environment where a space where the speaker is installed is small have a small cabinet volume due to its small size, reproduction of a low frequency is not sufficient and sound quality is inferior.SOLUTION: Speaker units are placed respectively in front of and behind a cabinet constituting a speaker system. The speaker units are individually driven by separate amplifiers. A filter capable of changing a high-frequency cutoff frequency is inserted into the driving amplifier of the rear speaker unit. Thus, the compact speaker system is provided that can reproduce a powerful bass and a wide sound field.SELECTED DRAWING: Figure 3

Description

Detailed Description of the Invention

The present invention relates to a small and high-quality speaker system.

  High-quality sound sources such as high-resolution sound sources are becoming popular, but when a source is obtained, a personal computer is often stored first. The sound is first played back by a speaker built in the personal computer or a small speaker system for the personal computer. However, the current situation is that many of the sounds played from these speakers are not high fidelity.

    Small speaker systems that can be used on desktops where computers are placed are often installed in a limited space, so the cabinet volume is often less than 2 liters (L). For this reason, the bass is insufficient and the diameter of the speaker unit is small, so that the efficiency is low and the maximum volume that can be obtained is small.

  In view of this, there have been some proposals for improving the bass characteristics of a small speaker system. For example, one speaker unit is arranged in a small sealed cabinet and one passive radiator is arranged on each of the speaker mounting surface and the opposing surface, so that it can be built in a flat display although it is not for desktop use. When it is built in a small size, sound is emitted from the front surface of the display and part of the low sound is also emitted from the back surface through a passive radiator (Patent Document 1 Japanese Patent Application Laid-Open No. 2010-114612). This is a development of a general passive radiator system, and the bass can be expected to be smaller than a closed cabinet with the same volume.

  There is a bass-reflex type cabinet in which the bass reflex is doubled and a low-frequency resonance cavity is provided to allow reproduction to a lower frequency (Bent Patent Document 2 Utility Model Registration 3196822). issue). The speaker of this device is well considered, but the inside of the cabinet is complicated and there is a limit to downsizing.

  Also, using two speaker units, they are placed facing the cabinet cabinet, one emits sound directly to the outside, the other emits sound to the second adjacent cabinet, and the sound is sent to the bass reflex. A method of guiding outside by a duct has been proposed (Patent Document 3 Japanese Patent Laid-Open No. 2005-151236). This method is designed to make up for the lack of bass, which is a weak point of small speaker systems, but requires two cavities inside the cabinet, and there is still a limit to downsizing the cabinet.

  JP 2010-114612 A   Utility model registration No. 3196822   JP-A-2005-151236

A small speaker system used in a narrow environment where the space where speakers are placed is limited, such as desktops, etc., is small, so the cabinet volume is small and low frequency reproduction is like a general audio speaker system The sound quality was often inferior.
Even in such a small speaker system, the present invention is a high-quality speaker that is excellent in low-frequency reproduction while using a cabinet with a relatively simple structure, and that can reproduce sound field richly and obtain sufficient reproduction volume. A system is provided.

  In order to solve the above problems, the present invention is such that speaker units are arranged before and after a cabinet constituting a speaker system, and are individually driven by separate amplifiers. Inserts a filter that can change the high cut-off frequency.When the cabinet is configured as a bass-reflex type, set the bass-reflex resonance frequency to less than half of the lowest resonance frequency of the speaker unit. By providing a structure in which the mounting surface of the rear speaker unit is inclined even when there is not enough space, the speaker system can reproduce a small but powerful bass and a wide sound field.

That is, the present invention adopts the following configuration in order to solve the above problems.
Configuration 1
A speaker system in which speaker units are arranged on the front and rear sides (sound emission side and rear side) of one cabinet, and these speaker units are driven by two independent amplifiers.

Configuration 2
Speaker units are arranged before and after one cabinet, and these speaker units are configured to be driven by two independent amplifiers, so that the high-frequency cutoff frequency can be varied for the amplifier that drives the speaker unit on the back side. A speaker system with a filter inserted.

Configuration 3
Speaker units are arranged before and after each cabinet, and these speaker units are driven by two independent amplifiers. When the cabinet is a bass reflex type, it is determined from the cabinet volume and bass reflex port. By setting the resonance frequency F0b of the bass reflex to be less than half of the lowest resonance frequency F0c of the speaker determined from the cabinet volume, a characteristic curve that attenuates toward the low band between those resonance frequencies is -6 dB / oct. -Speaker system about 12dB / oct.

Configuration 4
Speaker units are arranged before and after each cabinet, and these speaker units are configured to be driven by two independent amplifiers. The mounting surface of the rear speaker unit is the same as that of the front speaker unit. A speaker system composed of a cabinet that is configured as a surface with an angle rather than parallel to the mounting surface.

  According to the present invention, the sound radiated from the speakers arranged before and after the cabinet is substantially in phase even at the listener position in a low frequency band where the wavelength is sufficiently longer than the distance between the two front and rear speaker units. Therefore, the sound pressure is synthesized and rises. As a result, the low-frequency attenuation of the small speaker can be compensated, and the efficiency of the low-frequency range of the speaker system is increased. Therefore, a larger sound pressure can be obtained than when only one speaker unit is used.

On the other hand, sound with a frequency above the mid-range frequency whose wavelength is close to or shorter than the distance between the two speaker units is diffused into the room because the sound radiated from the back side is highly straight in the actual room. And reach the listener's ear. The sound radiated from the speaker arranged in the forward direction on the listener side directly reaches the listener's ear, and then diffuses into the room to be reflected and reaches the listener's ear again. Because of these, those sounds reflected on the wall are out of phase, and the sound pressure hardly rises, and the listener feels that the reverberant sound has increased. As a result, the reproduced sound produced by this system has a lower sound than that when there is only one speaker unit, and a reproduced sound in which the reproduced sound field is expanded due to an increase in reverberant sound can be obtained.

Furthermore, by driving these two speaker units with separate amplifiers, the sound pressure level from the two speaker units can be adjusted to approximately the same level by adjusting the volume even when the two speakers are not the same. The amount of bass and reverberation can be adjusted to a state suitable for the environment where the listener is listening. In addition, by inserting a filter to change the high-frequency cutoff frequency into the amplifier that drives the speaker on the back side, and adjusting it by the user, by reducing the sound above the mid-frequency radiated from the back, It is possible to suppress the increase in reverberant sound according to the user's preference and enhance only the low sound.

  When the speaker system is a bass reflex type and is put in a small cabinet having a volume smaller than twice the equivalent volume of the speaker unit, the resonance frequency F0b of the bass reflex determined from the cabinet volume and the bass reflex port is determined from the cabinet volume. By setting the frequency to be less than half of the lowest resonance frequency F0c, the attenuation characteristic toward the low frequency in the band between these resonance frequencies can be moderated to about −6 dB / oct to −12 dB / oct. It becomes possible to effectively use the enhancement of the bass by synthesizing the low frequency band sound radiated from the two speakers.

FIG. 1 is a block diagram illustrating the configuration of the speaker system according to the first embodiment. FIG. 2 is a diagram showing that the low-frequency characteristics according to the first embodiment are enhanced. FIG. 3 is a block diagram illustrating the configuration of the speaker system according to the second embodiment. FIG. 4 is a block diagram illustrating the configuration of the speaker system according to the third embodiment. FIG. 5 is a diagram showing that the frequency characteristic according to the third embodiment is improved. FIG. 6 is a diagram illustrating that the low-frequency characteristics according to the third embodiment are enhanced. FIG. 7 is a block diagram illustrating the configuration of the speaker system according to the fourth embodiment.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

    In the first embodiment, speaker units 3a and 3b are respectively arranged on the front and rear baffle surfaces 4a and 4b of one cabinet 4, and they are driven by individual amplifiers 1a and 1b, and means for arbitrarily adjusting the volume, For example, the input signals are input to the two amplifiers 1a and 1b via the variable resistors 2a and 2b, respectively, and the speaker units 3a and 3b connected to the amplifiers 1a and 1b are driven.

In the first embodiment, when the two speaker units 3a and 3b are driven at the same volume, when the distance between the two speaker units 3a and 3b is compared with the wavelength of the sound, the distance between the two speaker units 3a and 3b. In a low frequency band where the wavelength is sufficiently long such that is less than ¼ of the wavelength of the sound, the sound is not directional and the phase is generally matched, so those sounds are synthesized and shown by the thick line in FIG. In this way, the sound pressure rises by about 6 dB at the maximum at the listener's ear in the front, and it is possible to compensate for the lack of bass, which was the biggest problem in a small speaker system.

When the frequency of the input signal is high and the distance between the two speaker units is half or less than the wavelength of the sound of the input signal, the listening position near the speaker (for example, At a position of 20 cm or less from the speaker system), some frequencies are synthesized in phase and sound pressure is increased, or conversely, the phase is reversed and canceled and sound pressure is decreased.

However, in an actual room, the listening position of the sound is generally 50 cm or more away from the speaker. In such an actual listening position in a reverberant room, the mid-range frequency and above are two front and rear. The phase of the sound radiated from the speaker changes in a complicated manner by overlapping the direct sound and the reflected sound, and the above-described synthesis and cancellation do not occur clearly. The listener listens to the direct sound from the front speaker first, so that the directionality of the sound is perceived, and further, the sound is reflected and compounded by the wall of the room, so the reverberation component increased. hear.

As a result, as a whole, the listener can hear the bass to be enhanced and the reverberation to increase and feel a rich sound. If the same thing is carried out for the left and right speaker systems of the stereo system, a deep sound field with a three-dimensional feeling can be felt.
When the two speaker units 3a and 3b arranged before and after the cabinet are not the same, the volume adjusting means 2a and 2b are arranged in front of the amplifier so that the volume can be arbitrarily adjusted. The sound pressure from the two speakers can be adjusted. Therefore, even in such a case, substantially the same effect as described above can be easily obtained.

  In the second embodiment, as shown in FIG. 3, speaker units 3a and 3b are arranged on the front and rear baffle surfaces 4a and 4b of one cabinet 4, respectively, and are driven by individual amplifiers 1a and 1b. The input signals are input to the two amplifiers 1a and 1b, respectively. The front stage of the amplifier 1b that drives the speaker unit 3b on the back side is provided with a high cut filter 7 that can change the high-frequency cutoff frequency, and after the volume is arbitrarily adjusted, the speaker unit 3b is driven through the amplifier 1b. By adopting such a configuration, it becomes possible to freely attenuate the frequencies above the mid-range radiated from the speaker unit 3b on the back side, so that it is possible to limit the increase in reverberant sound, and thereby the listener's Depending on the environment of use, it is possible to adjust the feeling of reverberation appropriate for the environment of use while maintaining the bass enhancement effect.

  The third embodiment is shown in FIG. 4 and is configured such that speaker units 3a and 3b are arranged in front and rear in one cabinet 8 in the same manner as the other embodiments, and are driven by individual amplifiers 1a and 1b. The input signals are input to the two amplifiers 1a and 1b, respectively. Under such a configuration, in order to make the cabinet 8 smaller, a bass reflex system in which a bass reflex duct 8a is provided in the normal cabinet 8 as shown in FIG. 4 is used. When the equivalent resonance sharpness Q0 of the speaker is around 0.5, the volume of the cabinet 8 is about twice the equivalent volume of the speaker unit, and the resonance frequency F0b of the bass reflex determined from the cabinet volume and the bass reflex port is set. By setting it to about 0.7 times the lowest resonance frequency F0c of the speaker determined from the cabinet volume, the low frequency flatness characteristic can be effectively extended.

However, in the case of the cabinet volume according to such a conventional calculation method, for example, when a small speaker having a diameter of about 10 cm is used, a cabinet volume of about 3 to 5 L is required. However, in the desktop environment, the volume of 3 to 5 L is a size that cannot be ignored, and in the case of a stereo system, it is necessary to install two speaker systems, and securing the space may be a problem. Therefore, there is a demand for both a further reduction in size and good bass characteristics.

  As this volume is reduced for miniaturization, the lowest resonance frequency F0c of the speaker increases, and the value of Q0c indicating the sharpness of resonance at that frequency also increases. For this reason, as shown by the broken line in FIG. 5, the frequency characteristic has a peak at F0c, and the characteristic below the bass reflex resonance frequency F0b is rapidly attenuated toward the lower frequency. Lowering is not preferable.

  Therefore, in the present invention, when the cabinet volume is placed in a small cabinet having twice or less the equivalent volume of the speaker unit, the resonance frequency F0b of the bass reflex is set to be equal to or less than half of the lowest resonance frequency F0c of the speaker. As shown in the actual battle, the Q value of F0c is lowered to attenuate the peak, and the frequency characteristic between these two resonance frequencies is a gradual characteristic curve of about −6 dB / oct to −12 dB / oct toward the low frequency range Can be. The low frequency sound radiated from the speakers arranged opposite to the front and rear of the cabinet is synthesized as described above, and the gentle attenuation characteristic curve can be enhanced by about +6 dB as shown by the thick line in FIG. Can compensate for bass attenuation. On the other hand, the sound in the mid-high frequency band increases the reflection component in the actual use environment, but does not increase the sound pressure, and as a result, a speaker system in which the attenuation characteristic in the low sound range is complemented can be realized.

  Example 4 is shown in FIG. 7 and takes into consideration the case where the back of the speaker system is not sufficiently paced in the actual use environment of the user. In such a case, the speaker unit 3b on the back side is used. For example, as shown in FIG. 7, the mounting surface 4 b of the rear speaker unit 3 b is angled rather than parallel to the mounting surface of the front speaker unit 3 a so that the radiated sound is not reflected immediately upon the wall surface. Thus, the sound radiated from the back side is reflected on the wall surface with a certain distance. In this embodiment, the mounting surface 4a of the speaker unit 3b on the back side and the wall surface on the back side are not in parallel, so in the sound radiated from the speaker unit 3b on the back side, Since the reflection from the wall surface is not uniform, the phase characteristics become more complex, and a rich reverberant sound can be obtained even in a narrow back space.

  The example in which the speaker system of the present invention is applied in the desktop environment has been described above, but the speaker system described in the first to fourth embodiments may be installed as a normal stereo system. Of course, it may be installed as an in-vehicle speaker system.

1a, 1b Amplifiers 2a, 2b Volume adjusting means 3a, 3b Speaker unit 4 Sealed cabinet 5 Frequency characteristic example when low frequency is not synthesized in a sealed cabinet 6 When low frequency is synthesized in a sealed cabinet Example 7 of frequency characteristics of filter 7 High frequency cutoff frequency variable filter 8 Bass reflex cabinet 9 Bass reflex resonance frequency F0b determined from cabinet volume and bass reflex port
10 Minimum resonance frequency F0c of speaker determined from cabinet volume
11 Frequency characteristics when the bass-reflex cabinet volume is reduced 12 Frequency characteristics when the bass-reflex cabinet volume is reduced and the frequency characteristics 13 when F0b ≦ 1 / 2F0c are combined and the low frequency is synthesized 14 Impedance characteristics of speaker unit in bass reflex cabinet

Claims (4)

In a speaker system in which the same speaker unit is disposed on the baffle plate of one speaker cabinet and the back surface opposite to the baffle plate, each speaker unit is driven by an independent amplifier. . 2. The speaker system according to claim 1, wherein a filter capable of changing a high cut-off frequency is inserted into an amplifier that drives the speaker unit on the back side. In a bass-reflex type speaker system in which the same speaker unit is arranged on the baffle plate of one speaker cabinet and the back surface facing the baffle plate, each speaker unit is equivalent to the speaker unit in a speaker system driven by an independent amplifier. The bass reflex resonance frequency determined by the duct and the volume of the cabinet having a volume less than twice the volume is set to be less than or equal to half the resonance frequency of the speaker unit determined by the volume of the speaker unit and the cabinet. system. 4. The speaker system according to claim 1, wherein the baffle for attaching the speaker unit on the back side is configured to be inclined rather than parallel to the baffle on the front side.

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