JP2024000668A - acoustic equalizer device - Google Patents

Abstract

To provide an acoustic equalizer device capable of easily flatting and improving a frequency characteristic of the volume in the low range of a speaker system.SOLUTION: A frequency A and a frequency B having a relation of A<B satisfy the following equation of a gain in the frequency A>a gain in the frequency B. The gain between the frequency A and the frequency B has a pair frequency gain characteristic that is changed in 6 dB/oct, and a pair frequency gain characteristic of a BEF (band elimination filter) as a center of a frequency C having a relation of C<B, and each of the frequency A, the frequency B, and the frequency C comprises means of univocally allowing a selection or an adjustment operation from a bore diameter of the speaker unit as an object.SELECTED DRAWING: Figure 4

Description

The present invention belongs to an audio device, and is used in an audio device in which a user prepares a speaker system and an amplifier separately and uses them in combination. The present invention relates to a device that allows even a user with little specialized knowledge to easily flatten, improve, and adjust the frequency characteristics of low-frequency sound pressure generated from a speaker.

As the first background art, a patent obtained by the inventor of the invention will be explained.

Patent No. 6699957

According to Patent Document 1, resonance in the low frequency range is mechanically suppressed using an acoustic resistance material made of an elastic material having small holes, such as urethane foam, or a flexible fiber material compressed to an appropriate density. The speaker unit is built into a box, which directs the sound pressure of the low frequency sound from the frequency where the sound pressure starts to become insufficient to lower frequencies, with a gain of 6 dB/oct up to 0.5 times the lowest resonance frequency of the speaker. By correcting it with an equalizer circuit that has a frequency-gain characteristic that increases the frequency with the slope of A speaker system using this speaker unit can also constitute an acoustic device capable of reproducing frequencies lower than ever before.

However, such audio equipment requires specialized knowledge unless the speaker unit, box, and amplifier including the equalizer circuit are provided as part of a complete product, such as a television or radio receiver. It cannot provide sufficient performance for general users without.

Furthermore, in audio equipment in which devices such as a speaker system, amplification device (amplifier), and CD player are provided separately and the user uses them in combination according to individual tastes, some of these devices are , at least a speaker system incorporating the mechanically suppressed resonance speaker unit mentioned above and an equalizer device for correcting the lack of low sound pressure for the speaker system must be provided as a set, otherwise the desired low to high frequencies will be lost. We cannot guarantee the same level of playback sound pressure as possible.

This is because the correction characteristics of the correction circuit must be adjusted according to specifications such as the speaker unit of the speaker system used for bass, the box in which it is installed, and the degree of resonance suppression. This is because it can only be done by a person who has specialized knowledge and the skills to use the appropriate measuring instruments.

Even some people who do not have the above-mentioned skills and have little acoustical or electrical expertise can purchase speaker units and board materials for boxes as parts, referring to published production examples and manuals. There are generally people who build their own speaker systems.

However, even for such self-made enthusiasts, it is difficult to manufacture equalizers and adjust correction characteristics to effectively flatten the frequency vs. sound pressure characteristics in the bass range in audio equipment such as the one disclosed in Patent Document 1 for the reasons mentioned above. is considered difficult.

In addition, the second background technology is a well-known technology that is not based on Patent Document 1, that is, a conventional speaker unit and box that does not suppress resonance, that is, a general bass reflex speaker system, or a general bass reflex type speaker system. There is a speaker system called a closed speaker system.

They are used in combination with an amplification device (amplifier), but if the parameter design of the speaker unit and box is inappropriate and the frequency vs. sound pressure characteristics in the bass range are undesirable, it may be necessary to install a graphic equalizer on the amplifier side. It is conceivable to improve the characteristics using a frequency-gain characteristic adjustment device. In such cases, it would be difficult to respond unless someone had the appropriate specialized knowledge and skills to use measuring instruments.

Therefore, the present invention provides a bass reflex type speaker system using a speaker unit that suppresses the low frequency resonance of the speaker unit, and other conventional general bass reflex type or closed box type speaker systems. Even those who are not enthusiasts and are trying to build a speaker system by purchasing a speaker unit and box production kit for the first time can easily flatten the bass frequency response of a speaker system. - Our goal is to provide an improved acoustic equalizer device.

Another object of the present invention is to provide an acoustic equalizer device that allows even those skilled in the use of measuring instruments to easily and precisely flatten and improve the frequency characteristics of the bass range.

Furthermore, when targeting a bass reflex speaker system that uses a speaker unit that suppresses low-frequency resonance, it is necessary to use multiple types of speaker systems based on differences in the diameter of the speaker unit and the size of the box. Our objective is to provide an acoustic equalizer device that can be easily applied when provided as a product.

In order to solve the above-mentioned problem, claim 1 provides a device for controlling the frequency versus sound pressure characteristics of the bass range of a speaker unit in charge of the bass range, the device comprising: , there is a relationship such as gain at frequency A > gain at frequencies higher than B, and the gain between frequency A and frequency B changes at a rate of 6 dB/oct, and frequency C has the relationship C < B. It has the frequency vs. gain characteristics of a central BEF (band elimination filter), and has a means to uniquely set, select, or adjust frequency A, frequency B, and frequency C based on the aperture of the target speaker unit. The present invention provides an acoustic equalizer device characterized by the following.

In order to solve the above-mentioned problem, a second aspect provides the acoustic equalizer device according to the first aspect, wherein the frequency A includes means for adjusting the frequency.

In order to solve the above-mentioned problem, in claim 3, the acoustic equalizer device according to claim 1 or claim 2 is provided with means for adjusting the gain at frequency C of the BEF centered on the frequency C. This is what was provided.

Therefore, in claim 1, it is possible for a person who does not have specialized knowledge or the skill to use a measuring instrument to obtain information without knowing the values of frequency A, frequency B, and frequency C determined from the specifications of the speaker unit or box used in the speaker system. , it is possible to appropriately set the frequency A, frequency B, and frequency C of the acoustic equalizer device only from the aperture information of the speaker unit, thereby easily improving the frequency versus sound pressure characteristics of the bass range of the speaker system.

According to claim 2, the frequency A according to claim 1 can be adjusted more precisely, thereby making it possible to improve the frequency versus sound pressure characteristics of the bass range of the speaker system more precisely.

According to claim 3, the peaks and troughs of the sound pressure at frequency C can be precisely adjusted, thereby making it possible to more precisely improve the frequency versus sound pressure characteristics of the bass range of the speaker system.

A diagram showing an example of the speaker system of Patent Document 1 A diagram showing the frequency versus sound pressure characteristics of the speaker system shown in Figure 1. A diagram showing the electrical system block configuration for driving the speaker system shown in Figure 1. A diagram showing an embodiment of the circuit of the equalizer device of the present invention A diagram showing frequency versus gain characteristics of the equalizer circuit 603 shown in FIG. 4 A diagram showing the frequency vs. sound pressure characteristics when the frequency vs. sound pressure characteristics shown in FIG. 2 are corrected by the frequency vs. gain characteristics shown in FIG. 5. A diagram showing the frequency versus gain characteristics of the BEF circuit 605 shown in FIG. A diagram showing frequency vs. sound pressure characteristics when the frequency vs. sound pressure characteristics shown in FIG. 6 are corrected by the frequency vs. gain characteristics shown in FIG. 7. A diagram showing another embodiment of the circuit of the equalizer device shown in FIG. 4 A diagram showing another embodiment of the circuit of the equalizer device shown in FIGS. 4 and 9. Diagram showing an example of a general bass reflex speaker system A diagram showing frequency vs. sound pressure characteristics when a valley in sound pressure is created between the resonance frequency due to the speaker unit and box internal space volume and the bass reflex resonance frequency due to the bass reflex duct and box internal space volume in the bass reflex type speaker system shown in Figure 11. A diagram showing frequency vs. sound pressure characteristics when the frequency vs. sound pressure characteristics in FIG. 12 are corrected by the frequency vs. gain characteristics shown in FIG. 5. A diagram showing frequency vs. sound pressure characteristics when the frequency vs. sound pressure characteristics in FIG. 13 are corrected by the frequency vs. gain characteristics shown in FIG. 7. A diagram showing frequency vs. sound pressure characteristics when the strength of bass reflex resonance is set to an appropriate level using the frequency vs. sound pressure characteristics shown in Figure 14. Diagram showing an example of a general closed speaker system Diagram showing frequency vs. sound pressure characteristics of the speaker system shown in FIG. 16 A diagram showing frequency versus sound pressure characteristics when the frequency versus sound pressure characteristics of FIG. 17 are corrected by the frequency versus gain characteristics of FIG. 5. A diagram showing the frequency vs. sound pressure characteristics when the frequency vs. sound pressure characteristics shown in FIG. 18 are corrected by the frequency vs. gain characteristics shown in FIG. 7. A diagram showing the frequency vs. sound pressure characteristics when a peak is created in the sound pressure due to incorrect setting of the box internal space volume with respect to the specifications of the speaker unit in the speaker system shown in Fig. 16. A diagram showing frequency versus sound pressure characteristics when the frequency versus sound pressure characteristics of FIG. 17 are corrected by the frequency versus gain characteristics of FIG. 5. A diagram showing the frequency vs. sound pressure characteristics when the frequency vs. sound pressure characteristics shown in FIG. 18 are corrected by the frequency vs. gain characteristics shown in FIG. 7.

First, an embodiment of the equalizer device of the present invention will be described based on Patent Document 1, in which a speaker unit subjected to mechanical resonance suppression is applied to a bass reflex type speaker system.

FIG. 1 is an explanatory diagram of an embodiment in which a speaker unit 1 with mechanical resonance suppression is attached to a bass reflex box 2. An acoustic resistance material 3 is provided on the box interior space 201 side of the diaphragm 101 of the speaker unit 1. The acoustic resistance material 3 is covered with a partition wall 4 so that only a part of its surface 301 is exposed in the box interior space 201. The signal is configured to be transmitted to the box interior space 201 only through 301. Further, the box 2 is also provided with a bass reflex duct 202.

In addition, in claim 3 of Patent Document 1, the resonance means of the enclosure is "based on a combination of the equivalent mechanical stiffness of the main space of the enclosure and the equivalent mechanical mass provided separately", and as explained in the patent, it is a bass reflex type. Although the box is not limited, the explanation will be based on a bass reflex type box as a representative type.

Further, although FIG. 1 corresponds to the embodiment of FIG. 24 in Patent Document 1, the "mechanical resonance suppressing means by damping the vibration of the diaphragm of the speaker unit" in claim 1 of Patent Document 1 is patented. In FIG. 24 of Document 1, this corresponds to the sound absorbing materials 23 and 24, and in FIG. 1 of the present patent, it corresponds to the acoustic resistance material 3. Furthermore, in claim 2 of Patent Document 1, "the mechanical resonance suppressing means includes a rear surface of the diaphragm of the speaker unit and an opening spaced a predetermined distance from the rear surface of the diaphragm, and the vibration is transmitted only through the opening. "An acoustic resistance material having breathability and sound absorption is arranged between the diaphragm and the opening in a small space in which air vibrations caused by the vibration of the plate are propagated to the main space inside the enclosure", as disclosed in Patent Document 1. In Fig. 24 of this patent, sound absorbing materials 23 and 24 are placed inside the wall 20 constituting the small space and the opening 2101 of the small space, but in Fig. 1 of the present patent, the acoustic resistance material 3 is placed with its surface 301 remaining. This corresponds to a structure in which the partition wall 4 is covered with a partition wall 4.

FIG. 2 shows frequency versus sound pressure characteristics when the voice coil (not shown) of the speaker unit 1 of the speaker system shown in FIG. 1 is driven with a uniform voltage at each frequency. In FIG. 2, frequency A is a frequency in the vicinity of the lowest mechanical resonance frequency fo of the speaker unit 1 in FIG. Frequency C, which is the frequency at which the sound pressure on the bass side starts to decrease compared to the sound pressure on the treble side when the fo resonance of the unit is completely suppressed, is the resonance between the speaker unit 1 and the box interior space 201 when the speaker unit 1 is installed in the box 2. The frequency, frequency D, is the resonance frequency of the box interior space 201 and the bass reflex duct 202, and is empirically set to about 1/2 of fo.

In Fig. 2, (a) shows the frequency vs. sound pressure characteristics when the resonance of the speaker unit 1 is completely suppressed by the acoustic resistance material 3, and is a low frequency starting from frequency B, which uses the diameter of the speaker unit as a parameter, which will be described later. The sound pressure decreases by 6 dB/oct toward the frequency A, but the decrease stops due to the overlap of the sound pressure peak (2) caused by the bass reflex resonance of the bass reflex duct 202 and the box interior space 201 centered at the frequency D at the frequency A.

(C) is the frequency vs. sound pressure characteristic when the acoustic resistance material 3 is omitted and the resonance of the speaker unit 1 is not suppressed, and the frequency is higher than the resonance frequency C determined by the volume of the internal space 201 of the speaker unit 1 and the box 2. In this case, the sound pressure is almost constant, and below frequency C, the sound pressure decreases at a theoretical rate of 12 dB/oct toward lower frequencies.

Here, the resonance of the speaker unit 1 is equal to resonance at a resonance frequency C determined by the volume of the internal space 201 of the speaker unit 1 and the box 2. In other words, the lowest mechanical resonance frequency fo of the speaker unit 1 is the resonance frequency when the speaker unit 1 is not attached to a finite box, and when it is attached to a finite box, the resonance frequency becomes higher than fo. The resonant frequency is frequency C in FIG. To explain this in other words, the acoustic resistance material 3 in FIG. It is restraint.

(B) is the frequency versus sound pressure characteristic when the mechanical resonance of the speaker unit 1 is not completely suppressed by the acoustic resistance material 3, and is located between (A) and (C), but it depends on the degree of resonance suppression. It approaches the characteristics of (a) or (c).

FIG. 3 is a block configuration diagram of an electric circuit that drives the speaker system shown in FIG. 1, in which 5 is a well-known sound source device such as a CD player, 6 is an equalizer device of the present invention, and 7 is a circuit connected to the speaker system. This is a well-known power amplification device (power amplifier).

Although not shown in Figure 3, it is commonly called a preamplifier or control amplifier, and is used to select and connect sound source devices and recording devices, adjust volume, and adjust bass and treble frequencies in a different sense from the equalizer device of the present invention. Devices that perform level adjustment (commonly known as tone control) are used between 5 and 7, but they are not necessary for explaining the present invention and are well known, so their illustrations and explanations are omitted for convenience. .

FIG. 4 shows an example of a detailed circuit of the equalizer device 6 of the present invention shown in FIG. 3, which is constructed of analog circuits mainly including operational amplifiers. In FIG. 4, 601 is a variable resistor for level adjustment, 602 is an amplifier, 603 is an equalizer circuit using C and R, 604 is a buffer amplifier, and 605 is a BEF (band elimination filter) circuit whose gain is attenuated within the frequency band. It is.

In the figure, the processing order of the frequency vs. gain characteristic of the input signal is the equalizer circuit 603 and the BEF circuit 605, but the order before and after that, other amplifier circuits, buffer amplifiers, etc. can be changed as necessary.

In addition, the basic circuits of 602, 603, 604, and 605 are well known as operational amplifier and filter circuits, and I think it is unnecessary to explain their detailed operation again, but the frequency vs. gain characteristics of the equalizer circuit using CR of 603 As shown in FIG. 5, gain below frequency A>gain above frequency B, and changes between frequency A and frequency B at 6 dB/oct. For convenience of explanation, frequencies A and B in FIG. 5 correspond to frequencies A and B in FIG. 2 and have the same relationship, but in reality, a slight deviation is allowed as will be described later.

Frequency A and frequency B are determined by R1, C1, and R2 in the circuit as frequency A = 1/(2π(R1+R2)C1) and frequency B = 1/(2πR2C1), but in the circuit of this example, they are connected at SW1. By switching C1 to C11&#12316;C13, both frequency A and frequency B can be switched stepwise as a set, and frequency A can be changed by variable resistor r1 in R1, and frequency B can be changed by variable resistor r2 in R2. I am able to adjust it. The reason will be explained later.

FIG. 6 is a diagram explaining the correction effect of the equalizer circuit 603 on the frequency versus sound pressure characteristics shown in FIG. 2. Each of the sound pressure characteristics (A) and (D) shown in FIG. By correcting the frequency vs. gain characteristics shown, the sound pressure characteristics (A') and (D') are obtained.

When correcting with the frequency versus gain characteristics shown in Fig. 5, if the mechanical resonance suppression by the acoustic resistance material 3 is not complete, that is, if the characteristics before correction are (b) and (c) in Fig. 2, the corrected In FIG. 6, in contrast to the flat characteristic (A'), there are peaks of sound pressure at frequency C as shown in (B') and (C').

The BEF circuit 605 in FIG. 4 is generally used in a device called a graphic equalizer. In a typical graphic equalizer, the circuit portion within the dotted line frame is divided into multiple bands of different center frequencies, for example, 30, They are installed at each frequency of 60, 120, 250, 500...Hz, and the gain at the center frequency can be decreased or increased.

Regarding the constituent elements of the equalizer device of the present invention, it is a necessary and sufficient condition that the center frequency, that is, the circuit has only one band, and that the gain can be adjusted only in the decreasing direction, but it is also possible to include adjustment in the increasing direction. I can't use it. For convenience of explanation, the center frequency C of the band is assumed to have the same relationship as the center frequency C in FIG. 2, but in reality, a slight deviation is allowed as will be described later. Further, the gain of the center frequency C can be adjusted as shown in FIG. 7 by using the variable resistor r3 shown in the figure. Note that the gain adjustment shown in FIG. 7 shows only the decreasing direction from zero.

For R3 and r3, in a normal graphic equalizer, there is no R3 and only r3 (or the resistance value of R3 is zero), and the slider (variable terminal) position of r3 connected to C2 is the midpoint of the resistance and the gain is adjusted. The resistance value above the slider in the diagram is zero and the gain is minimum (the gain attenuation is maximum), and the resistance below the slider in the diagram is zero and the gain is maximum (or the gain increase is maximum). However, in the present invention, the resistance value of R3 can be selected from a range up to 0 (zero) &#12316;r3. The reason for this will also be explained later.

Also, the center frequency C is determined by the formula of center frequency C=1/2π√(C2C3R4R5) using C2, C3, R4, and R5 in the figure. I try to change the settings step by step as a set. The reason for this will also be explained later.

Note that like frequency A and frequency B, frequency C can also be adjusted, and in this case, a variable resistor r5 may be provided, but r5 is not an essential component.

As described above, FIG. 7 shows the frequency versus gain characteristics of the BEF circuit 605. As mentioned above, the band center frequency C of BEF is the same as the frequency C in Figs. 2 and 6, and the bandwidth of the attenuation characteristic is appropriately set with circuit constants so as to roughly correspond to the frequencies D and B in Fig. 6. shall be carried out.

The degree of gain attenuation at the center frequency C is adjusted by r3 in Figure 4 as described above, but it should be at most the difference between the sound pressures (C') and (A') at frequency C in Figure 6, and at the minimum. Set the slider between zero and r3 to be approximately halfway between the maximum and minimum. In other words, (C") in FIG. 7 is the inverse characteristic of the difference (H'-I') between (C') and (A') in FIG. 6, and (B") in FIG. 7 is the inverse characteristic of (B') in FIG. The circuit constants are configured to have the inverse characteristic of the difference (lo'-a') between and (a').

The characteristic (A'') in FIG. 7 represents zero gain attenuation, which is achieved by setting R3=r3 in the circuit diagram of FIG. 4 and adjusting the slider of r3 to the full lower position in FIG.

Now, regarding the equalizer device of the present invention configured as described above, regarding the relationship between the frequency vs. sound pressure characteristics on the speaker system side, frequencies A, B, and C in FIG. 2 and the switching of switching SW1 and SW2 in FIG. A more detailed explanation is required now. In fact, in the speaker system configured as shown in Fig. 1, the frequencies A, B, and C in Fig. 2 are generally summarized to similar values depending on the diameter of the speakers used, and in the equalizer device, the frequencies A, B, and C in Fig. 7 are summarized into similar values. For the frequency C, a representative value may be used for each aperture, and this may be used as the center value (reference value).

To explain this first, frequency B is approximately 1000 Hz for a speaker with a nominal diameter of 10 cm, and approximately 500 Hz for a speaker with a nominal diameter of 20 cm. This is generally known as the relational expression Ka = 2πa/λ (a: radius of the disc, λ: wavelength) that expresses the radiation impedance of a disc, and when Ka is less than 1, the effective radiation impedance decreases and vibration It is said that when the plate vibrates with the same amplitude, the sound pressure decreases as the impedance decreases. This is because the frequency at which Ka is 1 is about 1000 Hz when the diameter of the disk is 10 cm (assuming radius a≈5 cm), and about 500 Hz when the disk diameter is 20 cm (assuming radius a≈10 cm). In reality, in commercially available speaker units, even if the nominal diameter is the same, the radius of the diaphragm varies slightly from product to product, and the frequency B also varies slightly, but in general, the frequency B varies depending on the speaker being used. There is no problem in determining a representative value uniquely based on the caliber and using that as the central value (reference value).

Next, as mentioned above, frequency A is considered to be a range of 0.5 times twice the fo of the speaker unit, but this fo is also similar to frequency B in speaker units currently on the market. Depending on the aperture, for example, a speaker unit with a diameter of 10cm has a frequency of around 80Hz, a speaker unit with a diameter of 12'16cm has a frequency of around 50'70Hz, and a speaker unit with a diameter of 20cm has a frequency of around 40Hz. (This is intended only for commercially available products that have been carefully considered for bass reproduction for audio purposes, and that are often used for home-made purposes.) Therefore, if the frequency A is uniformly corrected by an appropriate magnification within the range of 0.5 x 2 for the average fo for each aperture of the speaker unit used, the representative value can be uniquely determined by the aperture. There is no problem in determining this value and using it as the central value (reference value).

Furthermore, the frequency C is approximately determined by the aperture of the speaker unit used, such as approximately 1.5 times the fo of the speaker unit used, and approximately 2 times the fo of the speaker unit used, such as approximately 1.5 times the fo of the speaker unit used.

This is because, in Patent Document 1 presented in the first prior art, the resonance frequency of the bass reflex duct of the bass reflex box, that is, the frequency D, is empirically set to approximately 1/2 of the fo of the speaker unit used. As mentioned above, the resonance frequency of the bass reflex duct in this case is calculated from the cross-sectional area and length of the duct and the internal volume of the box, so once the desired bass reflex resonance frequency is determined for each speaker unit diameter, it can be used for practical purposes. If the duct cross-sectional area and length are set, the internal volume of the box will naturally be constrained to a similar size.

Furthermore, the external dimensions of the speaker unit of the diameter to be used must be able to be installed in the box with an appropriate fit, and due to these two constraints, the reasonable and practical internal volume of the box is limited to a certain range for each diameter of the speaker unit. This is because it will be done.

For example, when the speaker unit has an aperture of 10 cm and an fo of 80 Hz, the internal volume of the box is designed within a range of approximately 3L&#12316;10L due to the above constraints. At this time, the resonance frequency C of the speaker unit and the internal space of the box is approximately 130 Hz (approximately 1.6 times of fo) for 3L, approximately 110 Hz (approximately 1.4 times of fo) for 5L, and approximately 100 Hz (approximately 1.4 times of fo) for 10L. However, the magnification of the resonant frequency C with respect to fo is determined to be approximately 1.5 times (120 Hz) as a representative value, and this may be used as the center value (reference value).

Similarly, when the speaker unit has a diameter of 20 cm and fo is 40 Hz, the internal volume of the box is often designed to be in the range of about 15 L&#12316;40 L for the same reason as in the case of a speaker unit with a diameter of 10 cm. At this time, the resonance frequency C of the speaker unit and the internal space of the box is 100Hz (approximately 2.5 times the fo) for the 15L, 80Hz (approximately twice the fo) for the 20L, and 65Hz (approximately 1.6 times the fo) for the 40L. ) However, the magnification of the resonant frequency C with respect to fo is determined to be approximately twice (80 Hz) as a representative value, and this may be used as the center value (reference value).

In the explanation of frequency C above, this indicates that a slight frequency difference occurs between the frequency C on the equalizer side using the representative value and the actual frequency C on the speaker system side. Verifying the effect on the sound pressure characteristics, the ratio of the frequency C on the speaker system side and the frequency C on the equalizer device side, that is, (frequency C on the speaker system side) / (frequency C on the equalizer device side) is 0.5 or 2, a maximum sound pressure step difference of 6 dB occurs near frequency C in the frequency versus sound pressure characteristic. This is because the sound pressure difference between characteristics (c) and (a) in Figure 6 is 6 dB/oct except for the position of frequency C, and the sound pressure difference when the frequency changes twice is 6 dB. .

However, among the several cases mentioned above, the worst condition in which (frequency C on the speaker system side)/(frequency C on the equalizer device side) is the maximum is the case where the diameter is 20 cm and the internal volume of the box is 15 L, and the ratio is It is 1.25. The effect on the sound pressure at this time is only to the extent that a sound pressure step difference of 1.5 dB, ie, 1/4 of 6 dB, appears near frequency C. In the frequency versus sound pressure characteristics of speaker systems that are actually on the market, it is normal for there to be unevenness of ±6&#12316;10 dB within the reproducible frequency range, but even that is within the normal range, so the sound level is 1.5 dB. The pressure difference is not very large. Therefore, there is almost no problem even if there is a slight frequency difference between the actual frequency C on the speaker system side and the frequency C on the equalizer side determined by its representative value.

For the same reason, for frequencies A and B, the equalizer may use representative values for each diameter of the speaker unit used. In addition, in the explanation, the representative value is further replaced with the center value (reference value) because frequency A, frequency B, and frequency C take into consideration the existence of adjustment means using r1, r2, and r5 in addition to switching between SW1 and SW2. This is because it is assumed that a center (reference) position is set at the adjustment position and that the representative value is obtained when the adjustment is at that position. Of course, it goes without saying that the above sound pressure level difference can be eliminated by adjustment using the adjustment means.

From the above, it is possible to uniquely determine frequency A, frequency B, and frequency C using only information about the diameter of the speaker unit to be used.

Therefore, in the equalizer device of the present invention, the equalizer device is provided with a changeover switch that displays the diameter of the speaker unit to be used, and the frequency A, frequency B, and frequency are changed inside the equalizer device according to the switching position of the switch. If C is set to be switched to its center value (reference value), the user can simply switch the switch knob of the equalizer device depending on the diameter of the speaker unit to be used, and the user can change the size of the speaker unit, box size, etc. It is possible to approximately appropriately set each frequency based on the specifications of the frequency A, frequency B, and frequency C to be set by calculations, experiments, etc. without knowing the actual frequency A, frequency B, and frequency C themselves.

In the embodiment of the present invention, SW1 and SW2 correspond to changeover switches depending on the diameter of the speaker unit. The circuit example in Figure 4 shows only the circuit for one side of L or R of both LR stereo channels, and with only one circuit, SW1 has a switch with 1 circuit and 3 contacts, and SW2 has a switch with 2 circuits and 3 contacts. It becomes necessary. Therefore, in order to switch and select both LR CHs at once, SW1 requires a switch with 2 circuits and 3 contacts, and SW2 requires a switch with 4 circuits and 3 contacts. These SW1 and SW2 may be made independent or may be combined into one with 6 circuits and 3 contacts. Further, SW2 may be provided separately on the C2 side and the C3 side, and there is no problem as long as the switching position can be instructed by the aperture of the speaker unit. Note that the number of contacts can be increased or decreased depending on the type of caliber of the speaker unit to which it is assumed to be applied.

Furthermore, on the surface of the equalizer device, the SW switching position may be indicated only by symbols and frequency notation, and in the instruction manual, etc., the correspondence between the speaker unit aperture and the SW switching position, that is, the symbol and frequency, may be shown as a table. .

In the equalizer device of the present invention as described above, when the aperture of the speaker unit to be used is selected by switching SW1 and SW2, and frequency A, frequency B, and frequency C are switched in accordance with the aperture of the speaker unit, the above-mentioned As shown in FIG. 2, the frequency vs. sound pressure characteristics of the original speaker system shown in FIG. 2 are due to the frequency vs. gain characteristics of the equalizer circuit 603 shown in FIG. ;(c') exists in the range.

Next, when the frequency vs. sound pressure characteristic between frequency D and frequency B in FIG. , corrected to the frequency vs. sound pressure characteristics shown in FIG.

The mechanical resonance of the speaker unit 1 is not completely suppressed by the acoustic resistance material 3 of the speaker system shown in FIG. 1, and the frequency vs. sound pressure characteristics shown in FIG. ) and (c), by leaving the r3 slider of the BEF circuit 605 at the center position for gain adjustment, the frequency vs. sound pressure shown in Figure 6 can be achieved by simply switching SW1 and SW2. The peak (b') of the sound pressure at the characteristic frequency C can be flattened as shown in FIG. 8(a).

If the mechanical resonance of the speaker unit 1 is nearly completely suppressed by the acoustic resistance material 3 of the speaker system shown in FIG. 1, and the frequency vs. sound pressure characteristic shown in FIG. If the slider is at the center position of the gain adjustment and only SW1 and SW2 are switched, the sound pressure (A') at frequency C in the frequency vs. sound pressure characteristics shown in Figure 6 will change to the frequency as shown in Figure 8 (b). At C, a valley of sound pressure is created. In that case, by adjusting the slider r3 and adjusting the frequency vs. gain characteristic in FIG. 7 to the (A'') side, it is possible to bring it closer to (a) in FIG.

On the other hand, if the suppression of the mechanical resonance of the speaker unit 1 by the acoustic resistance material 3 of the speaker system shown in FIG. 1 is hardly effective and the frequency vs. sound pressure characteristic shown in FIG. If the r3 slider is at the center position of the gain adjustment and only SW1 and SW2 are switched, the sound pressure (C') at frequency C in the frequency vs. sound pressure characteristic shown in Fig. 6 will be as shown in Fig. 8 (c). A peak of sound pressure is created at frequency C. In that case, by adjusting the slider r3 and adjusting the frequency vs. gain characteristic in FIG. 7 to the (c'') side, it is possible to bring it closer to (a).

This adjustment can be done precisely using a measuring instrument, but it can also be done appropriately so that the musical tone sounds more preferable just by the auditory sensation.

The reason why this kind of adjustment is necessary is that in practical mechanical resonance suppression, the frequency versus sound pressure characteristic will fall somewhere between the characteristic curves (c) and (a), as shown in (b) in Figure 2. This is because the degree of suppression varies depending on the speaker unit used, the acoustic resistance material used, the degree of compression of the acoustic resistance material, etc., and the position between (c) and (b) cannot be limited. . If resonance could be completely suppressed, such adjustments would not be necessary, but in order to completely suppress resonance, the flow of air that goes back and forth inside the acoustic resistance material is sufficient to stop the vibration of the diaphragm of the speaker unit. This is because the vibration of the diaphragm must be suppressed, and the important sound generation is also suppressed, so mechanical resonance suppression has to be half-hearted.

Here, the characteristics shown in Figure 2 (c) are the frequency vs. sound pressure characteristics when the speaker unit is not subjected to any mechanical resonance suppression using an acoustic resistance material. The sound pressure is almost constant until the resonance frequency C determined by the volume, and the sound pressure decreases from the frequency C at a slope of 12 dB/oct.

Therefore, the gain at the center frequency C of the BEF circuit 605 in FIG. If it is possible to adjust the characteristics, it is possible to approximate the characteristics shown in (a) in Figure 2 when realistic mechanical resonance suppression is implemented, and the degree of mechanical resonance suppression of the manufactured speaker system can be adjusted. It is also possible to accurately match the characteristics of (A) by adjusting the remaining ±1/2 depending on the amount. In other words, the center value (reference value) of the slider r3 may be set at the center position of the gain adjustment.

In an extreme case, even in a speaker system configured by removing the mechanical resonance suppressing means by the acoustic resistance material 3 from the configuration requirements of Patent Document 1 presented in the first prior art, the center frequency of the BEF circuit of 605 C This suggests that it is possible to obtain the same effect as suppressing mechanical resonance by adjusting the gain in the patent and construct a compact acoustic device with the same bass reproduction ability as in the patent.

That is, as explained in Fig. 2, the bass reflex resonance frequency of the bass reflex box is set to approximately 1/2 of the fo of the speaker unit, and then frequency A is set to 0.5 &#12316;By adjusting it to about twice as much, a small acoustic device can be obtained that can reproduce a frequency of approximately 1/2 of the fo of the speaker unit used without performing mechanical resonance suppression using the acoustic resistance material 3. be able to.

However, in that case, the diaphragm and the interior space of the box are connected without any acoustic resistance material, so when the box is configured as a parallelepiped, the resonance that occurs depending on the distance between the parallel walls inside the box is transmitted to the diaphragm. The problem remains that the resonant sound propagates directly from the diaphragm to the external space of the speaker system, that is, the resonant sound called so-called box noise is likely to be emitted to the outside of the box.

Adjustment of Frequency A and Frequency B can be done by adjusting the frequency to the optimum point using a measuring instrument, or by explaining the relationship between the adjustment position and frequency vs. sound pressure characteristics in the instruction manual, and checking the speaker unit and speaker unit to be used. Depending on the degree of suppression of mechanical resonance and the condition of the box, it may be possible to simply use the user's senses to adjust the position to a preferable audible position. The same applies when the frequency C is provided with an adjusting means.

Adjustment of frequency A and frequency B can be set so that frequencies at adjacent switching positions by SW1 can be continuously covered. For example, when adjusting frequency A, if the switching by SW1 is to specify 10 cm, 13 cm, and 20 cm in aperture, and frequency A is set to 80 Hz at the 10 cm aperture position and 60 Hz at the 13 cm position, then If the adjustment is configured so that the minimum adjustment is approximately 10 Hz on the negative frequency side, and the minimum adjustment is approximately 10 Hz on the positive frequency side, the frequency A can be adjusted almost continuously between the apertures of 10 cm and 13 cm. The same applies between 13cm and 20cm.

Furthermore, it is very preferable to adjust the frequency A so that the center value (reference value) is fo and the frequency A can be adjusted by about 1/2 to twice that value. This is because, in Patent Document 1, the frequency A is set to 0.5&#12316;2 times the fo of the speaker unit used, but the center value of the adjustment is set to 1 times the fo, and the adjustment range extends from the center value to the negative side. If you can adjust the positive side to 0.5x &#12316;1x and 1x &#12316;2x on the positive side and always set it to the center value, you can first adjust the fo of the speaker unit to be used by simply switching SW1. , and then adjust it by up to 0.5 times on the minus side and up to 2 times on the plus side for each caliber.

As mentioned above, it is explained that the resonance frequency D of the bass reflex duct and the internal space of the box is basically set to about 1/2 of the fo of the speaker unit used, but if the speaker unit diameter is 5 cm class, the fo is about 200Hz. Based on our experience with prototype speaker units of this type, we have successfully flattened the frequency vs. sound pressure characteristics even when the resonance frequency D was set to 70 Hz and the frequency A was adjusted to around 130 Hz.

In this performance, the frequency D is 0.35 times the fo of the speaker unit used, and the frequency A at that time is 0.65 times the fo, and the adjustment of the frequency A is 0.5 times the fo&#12316; Adjustable by setting a 1x range.

Also, according to experience using a speaker unit with a diameter of 10 cm and a fo of 80 Hz, it has been possible to flatten the frequency vs. sound pressure characteristics by adjusting frequency D to 40 Hz and frequency A to around 160 Hz. . In this performance, the frequency D is 1/2 of the fo of the speaker unit, and the frequency A at that time is twice the fo, and the adjustment of the frequency A is adjusted by setting a range of 1 x &#12316;2 times the fo. It is possible. Adjustment of frequency A can thus be used.

On the other hand, the adjustment range for frequency B is such that the only value for frequency B is calculated from the aperture of the diaphragm of the speaker unit, as mentioned above, so there is no need to make the adjustment range as wide as for frequency A, but the adjustment range for each aperture is The maximum negative side is 0.5 times &#12316;1 times the central value (reference value) calculated. On the positive side, I think it is sufficient to be able to adjust by 1x or 1.5x.

This adjustment function repeats what has already been said, but if you first set the adjustment positions of r1 and r2 of frequencies A and B, r3 of frequency C, and r5 as the center point (reference point), it will depend on the aperture. This has the advantage that even a person without specialized knowledge or skill in using measuring instruments can set Frequency A, Frequency B, and Frequency C appropriately by simply switching between SW1 and SW2. If the relationship between specifications such as the degree of resonance suppression, box volume, and duct resonance frequency, and the adjustment range is described in the equipment instruction manual, it will be easier for those with specialized knowledge and skills to use the measuring instruments. This has the effect that even a person who does not have such knowledge or technology can adjust frequency A and frequency B more precisely and preferably.

In addition, in FIG. 4, the capacitor C0 in front of the level adjustment circuit 601 is provided for cutting bass and may or may not be provided, but if provided, the cutoff frequency should be higher than the frequency A mentioned above. It is not desirable to do so. This is because the frequency A is important as one of the constituent features of the claims.

If the configuration is such that frequency A, frequency B, and frequency C are switched depending on the diameter of the speaker unit as in the embodiment shown in FIG. 4, it is also possible to prepare several types of C0 and switch them in the same way as C1, C2, and C3. However, it is also conceivable to provide only one type of value and set the cutoff frequency to be lower than the frequency A of the speaker unit with the largest diameter, or to be able to select the presence or absence of the cutoff frequency. Experience has shown that installing a C0 capacitor can sometimes make the sound cleaner.

FIG. 9 shows an example of a circuit of the equalizer device different from that shown in FIG. 4. The difference between Fig. 9 and Fig. 4 is that the switching between frequency A and frequency B of the equalizer circuit using C and R is performed by the values of R1 and R2, not by switching the capacitance of C1. It may be possible to use a variable resistor to change the frequency continuously, or it may be possible to change the frequency in stages.

When changing R1 and R2 continuously, changing frequency A and frequency B does not mean switching at a point, but the indicated position of the variable resistor knob at the position where the resistance of R1 and R2 reaches the required resistance value. By displaying the aperture and symbol of the speaker unit, it can be handled in the same way as a switching switch.

Another method is to configure a set of C1, C2, and C3 (C2 & C3) as a plug-in part as shown in Figure 10, and provide multiple types of plug-in parts for each diameter of the speaker unit. If the equalizer device side allows the plug-in parts to be exchanged and connected, the user can select the plug-in parts according to the diameter of the speaker unit and connect them to the equalizer device to adjust the frequency A, frequency B, and frequency. There is no problem with a structure that allows C to be set appropriately.

In an extreme case, C1, C2, and C3 are not switched, and the frequency A, frequency B, and frequency C of the equalizer device are fixed, and the equalizer device itself is adjusted according to the diameter of the speaker unit. This may be configured for a 20 cm diameter.

Next, as described in the second prior art, we will introduce a general bass reflex speaker system in which a speaker unit that does not take mechanical resonance suppression is combined with a bass reflex box, and a speaker unit that also does not take mechanical resonance suppression in a sealed box. Improving the frequency versus sound pressure characteristics of a combined general closed speaker system using the equalizer device of the present invention will be explained.

FIG. 11 shows a general bass reflex speaker system according to the second prior art, and FIG. 12 is a diagram illustrating the frequency versus sound pressure characteristics of a case where the design failed.

This failure example is caused by the fact that in the design of a general bass reflex box, the resonance frequency (frequency D') of the bass reflex duct 202' is different from the resonance frequency (frequency C') of the speaker unit 1' and bass reflex box 2' in FIG. If the setting is too low, in Figure 12, in the composite sound pressure characteristic (g) of the sound pressure characteristic without taking into account the bass reflex duct (e) and the sound pressure characteristic of the bass reflex duct (f), the frequency C' and the frequency D' This is an example of a sound pressure valley forming between the two.

In such a case, when using the equalizer device of the present invention to improve frequency vs. sound pressure characteristics, first connect the equalizer device of the present invention to the position shown in Figure 3, and then connect SW1 and SW2 of the speaker unit. Set to caliber. At this time, the frequency A is left at the center position (reference value) without adjustment. Next, the gain adjustment of frequency C is adjusted to the minimum gain (the maximum decrease in gain). Thereafter, the degree of bass reflex resonance is adjusted by filling the bass reflex duct with an acoustic resistance material such as glass wool, and the frequency A is adjusted to adjust the overall sound pressure balance by hearing or using a measuring device.

This adjustment will be explained in detail using FIG. 12&#12316;FIG. 16. In Fig. 12, the sound pressure characteristic (E) shows that due to the resonance between the speaker unit and the internal space of the box, the sound pressure at the center frequency C' of the resonance is raised to the same level as the sound pressure at the frequency B'. 'The sound pressure is characterized by a rapid drop at lower frequencies. It is generally said that the sound pressure decrease at frequencies lower than frequency C' occurs at 12 dB/oct.

Therefore, when the frequency interval between frequency C' and frequency D' is wide, the sound pressure at the overlapped part of sound pressure characteristics (E) and sound pressure characteristics (E) is both low, so the synthesized sound pressure characteristics are ( As shown in g), a valley in sound pressure occurs between frequency C' and frequency D'.

When using the equalizer device of the present invention, first, the frequency vs. sound pressure characteristics of the speaker system in FIG. 12 are corrected as shown in FIG. 13 by the frequency vs. gain characteristics shown in FIG. 5 of the equalizer circuit 603 in FIG. 4 in the device. be done.

At this time, the frequency B' in FIG. 12 depends almost only on the aperture of the speaker unit as described above, so if the apertures are the same, the frequency B' in FIG. It can be applied as is.

Next, the frequency vs. sound pressure characteristics shown in FIG. 13 are corrected as shown in FIG. 14 by the frequency vs. gain characteristics shown in FIG. 7 of the BEF circuit 605 of FIG. 4. At this time, by adjusting the gain at the center frequency C by r3 of the BEF circuit 605 to the minimum gain (maximizing the decrease in gain), the frequency C' of FIG. It is possible to flatten the peaks of sound pressure.

As shown in FIG. 14, the frequency C of the equalizer device does not strictly match the frequency C' of the general bass reflex speaker system to be improved, as described above. This is due to the fact that the fo of the speaker unit used differs slightly depending on the product, and it is mainly due to the general bass reflex type box and the patent document 1 presented in the first prior art, which is the original purpose of this equalizer device. This is because the volume of the internal space of the box differs between the bass reflex box and the bass reflex box shown in the figure, due to the difference in the concept of its construction.

In the example of FIG. 14, a case is explained in which the frequency C is slightly higher than the frequency C', but in general, the difference in the resonance frequency between the speaker unit and the volume of the box interior space due to the difference in the volume of the box interior space is As mentioned above, the discrepancy between frequencies C' and C' is only about a few tens of %, and the resulting sound pressure difference between frequency C and frequency C' is less than a few dB, so the mismatch between frequencies C' and C has almost no effect on the frequency vs. First, the peak of the sound pressure at the center frequency C' can be generally corrected by the BEF circuit at the center frequency C.

In FIG. 14, the sound pressure at the peak of the bass reflex resonance sound pressure (F') due to the bass reflex duct 202' and the box internal space 201' with the center frequency D' is corrected by the equalizer circuit 603 and the BEF circuit 605 in FIG. Therefore, it is expected that the sound pressure will be higher than the corrected sound pressure at frequency C' in FIG.

Therefore, if the sound pressure of the bass reflex resonance becomes higher than the corrected sound pressure at frequency C' as shown in FIG. 14, it is necessary to reduce the peak of this sound pressure appropriately. FIG. 15 is a diagram showing this situation. The sound pressure peak (F') at the resonance frequency D' in FIG. 14 is reduced by filling the bass reflex duct 202' in FIG. At the same time, adjust the frequency A and lower the height of the peak as shown in (F).This adjustment can also be done with a measuring device, or it can be adjusted appropriately simply by hearing. .

As explained above in FIG. 11&#12316;FIG. 15, even when there is a valley in sound pressure between frequency D' and frequency C' in a general bass reflex type speaker system as shown in FIG. Using the equalizer device according to the above, it is relatively easy to improve the condition so that there is no valley in the sound pressure as shown in FIG. If the equalizer of the present invention is not used, either change the speaker unit, change the box to lower the resonant frequency C', or shorten the duct length of the bass reflex duct to raise the resonant frequency D'. In either case, the mechanical features would have to be replaced, which would require a considerable amount of effort.

This is an effect of flattening the mechanical resonance caused by the speaker unit and the internal space of the box with the center frequency C' shown in FIG. 12 using the electrical correction means BEF circuit 605 and equalizer circuit 603 shown in FIG. 4, and reconstructing the characteristics. Therefore, only the characteristics can be improved while leaving the mechanical features as they are.

Although adjustment of frequency B and frequency C was not explained in the explanation of FIG. 11&#12316;FIG. 15, it goes without saying that the correction can be made more precise and appropriate by making appropriate adjustments depending on the situation.

From the above, although it takes effort to adjust the resonance degree of the bass reflex duct at frequency D' using an acoustic resistance material or to adjust frequency A, if the parameter design fails in a conventional general bass reflex speaker system, It is possible to improve the frequency versus sound pressure characteristics in the bass range even if you are not an engineer with specialized knowledge or measurement equipment.

Conversely, in a conventional general bass reflex speaker system, even if the internal volume of the box is intentionally set smaller than usual, if the equalizer device of the present invention is used, the bass sound will be the same as the proper setting. This means that it is possible to obtain frequency reproduction ability, and if it is a general bass reflex type speaker system with an appropriately set internal volume, the bass reflex duct of the speaker system can be modified to make it longer and the bass reflex resonance frequency D can be increased. ' by intentionally creating a valley in the frequency vs. sound pressure characteristics as shown in Figure 12, and applying the equalizer device of the present invention there, the low frequency reproduction of the common bass reflex speaker system at hand can be achieved. This means that the frequency can be expanded. This is equivalent to the case in which the speaker unit is not provided with mechanical resonance suppression means using an acoustic resistance material in the first prior art patent.

FIG. 16 shows a speaker system using a closed box according to the second prior art, and FIG. 17 is a diagram illustrating its frequency versus sound pressure characteristics.

In FIG. 17, frequency C'' is the resonance frequency of speaker unit 1'' and box internal volume 201'', and is theoretically higher than fo of speaker unit 1'', but with respect to fo and Q of speaker unit 1'', If the internal volume 201'' is appropriately selected, the sound pressure can be flattened at frequencies equal to or higher than the frequency C'', as shown in FIG.

When the equalizer device of the present invention is applied to such a closed speaker system, and the switching positions of SW1 and SW2 are adjusted to the diameter of the speaker unit 1'', first, the frequency response is adjusted by the correction characteristics of the equalizer circuit 603 shown in FIG. In the sound pressure characteristics, a peak of sound pressure occurs at frequency C'' as shown in (ch') in FIG. 18, and then due to the correction characteristic of the BEF circuit 605 shown in FIG. It is possible to improve the characteristics to flat characteristics.

In FIGS. 18 and 19, it is possible to replace the frequency C" with the frequency C and the frequency B" with the frequency B, as described above, without any problem, so the explanation will be made here assuming that C"≈C and B"=B.

At this time, if frequency A is set to be the same as or lower than the fo frequency of speaker unit 1'', the limit of bass frequencies that can be reproduced with the same sound pressure as mid-high tones can be set to a frequency higher than the fo frequency of speaker unit 1''. For example, if fo is 80Hz and a speaker unit with a diameter of 10cm is installed in a 5L sealed box, frequency C'' will be approximately 120Hz, but this can be improved to 80Hz. The following improvements can be made.

Next, an example will be described in which the equalizer device according to the present invention was used to improve the characteristics of a speaker system using the same closed speaker box when the design failed. An example of frequency vs. sound pressure characteristics in this case is shown in FIG. This example is a general sealed box, and the specifications of the speaker 1" and the box internal volume 201" are unreasonable, and the bass frequency C" is higher than the desired frequency, and the bass frequency C" is centered around the frequency C". This is an example of a situation where a mountain of sound pressure was created.

Such cases occur when the box size is designed to be smaller than the fo, aperture, diaphragm mass, and Q of the speaker unit being used, especially when the speaker unit's diaphragm mass is light and Q is large. This often occurs with speaker units.

In such a case, in order to improve the frequency vs. sound pressure characteristics using the equalizer device of the present invention, the negative (gain reduction side) adjustment range of the gain adjustment at frequency C of the BEF circuit 604 in FIG. It is necessary to expand the setting beyond what has been explained so far. To do this, it is necessary to set circuit constants that increase the Q of the BEF resonant circuit accordingly, but the constants of other CR elements including C2 and C3, R4 and R5 of the BEF circuit 605 must be set in advance. This explanation assumes that

Connect such an equalizer device to the position shown in FIG. 3, and first set SW1 and SW2 to the diameter of the speaker unit. At that time, each frequency is adjusted at the center (reference) position. Next, the gain adjustment of frequency C is adjusted to the maximum on the negative side.

This will be explained in detail using Fig. 20&#12316;Fig. 22, but in conclusion, except that the gain adjustment range at frequency C of the BEF circuit of the equalizer device is expanded to the negative side, Fig. ;The same is true in the case of FIG.

In FIG. 20, the sound pressure characteristic (H) shows that due to the resonance between the speaker unit 1'' and the box internal space 201'', the sound pressure at the center frequency C'' is raised to a higher level than the sound pressure at the frequency B'', and the sound pressure at the center frequency C'' is raised to a higher level than the sound pressure at the frequency B''. The sound pressure is characterized by a sudden drop at lower frequencies.

If the equalizer device of the present invention is used in this case, the frequency versus sound pressure characteristic will become as shown in FIG. 21 due to the correction characteristics shown in FIG. 5 of the equalizer circuit 603 in FIG. 4 in the device.

Next, the frequency versus sound pressure characteristic of FIG. 21 is corrected as shown in FIG. 22 by the correction characteristic of the BEF circuit 605 shown in FIG.

In other words, by using the equalizer device of the present invention, not only can the bass frequencies that can be reproduced by a closed speaker system be expanded downward, but also the sound in the bass range can be increased even if the setting of the speaker unit and box internal volume has failed. It can also improve pressure levels.

In the above, the setting of the center value of frequency A, frequency B, and frequency C is just an example, and if it were possible to set, switch, and adjust frequency A only from the caliber information of the applicable speaker, rights would be granted. shall be within the range.

In addition, in the explanation of the embodiment, the equalizer device is configured with an analog circuit, but a computer system is used as a digital filter, and the settings of frequency A, frequency B, and frequency C can be made using the aperture information of the applicable speaker unit. The scope of rights shall also include those that are

To summarize and explain the above explanation again, the acoustic equalizer device according to the present invention uniquely selects and adjusts the frequency A, frequency B, and frequency C of the equalizer device to representative values based on the aperture of the speaker unit used. Since the means is provided, even if there is a slight deviation between the frequency A, frequency B, and frequency C of the equalizer device and the frequency A, frequency B, and frequency C that are strictly necessary for the speaker system using the speaker unit, , the user can easily select an equalizer device based on the diameter of the speaker unit to be used without knowing the necessary frequencies A, B, and C, or easily adjust the bass range of the speaker system by operating the device's switching means. It becomes possible to flatten and improve the frequency versus sound pressure characteristics of

This selection and switching of frequency A, frequency B, and frequency C based on the diameter of the speaker unit can be done all at once or individually using a switching switch or a component plug-in, or it can be adjusted continuously with diameters and symbols attached. It is possible. Furthermore, it is possible to select the equalizer device itself without any switching or adjustment by making the aperture of the speaker unit correspond one-to-one with the equalizer device.

At this time, even if the frequency A, frequency B, and frequency C of the equalizer device are fixed as representative values and do not have adjustment means, it is possible to flatten and improve the frequency versus sound pressure characteristics in the bass range as described above. It is also possible to provide an adjustment means with a clear center value (reference value) position for adjustment. If such an adjustment means is provided, the adjustment means first selects the speaker aperture at the center value (reference value) position, and then adjusts the adjustment means based on the sense of hearing and measurement of the musical sound to more precisely determine the frequency vs. sound pressure. It is possible to flatten and improve the characteristics.

The adjustment means has great value at frequency A. This is because, in Patent Document 1, there is a range in the appropriate magnification of frequency A to fo depending on the aperture and fo of the speaker unit used, the frequency of bass reflex resonance, and the peak of sound pressure. is set to 0.5&#12316;2 times fo, but the present patent is not limited to the range of Patent Document 1, nor is the central value (reference value) fixed to 1 times fo.

The amount of attenuation of the BEF circuit at frequency C can be fixed as a constant value if the target speaker system is restricted to some extent. For example, according to Patent Document 1, when the speaker unit is limited to use in a speaker system in which mechanical resonance is suppressed by acoustic resistance means, (RO) between (A") and (C") in FIG. ”), or it is possible to fix (B”) close to (A”) or (C”) depending on the degree of suppression of mechanical resonance assumed. Furthermore, if the use is limited to a conventional general bass reflex type speaker system, it can be fixed to (c) in FIG.

However, if the target speaker system is not restricted, the amount of attenuation of the BEF circuit can be adjusted. In this case, the adjustment amount is set at a center value (reference value) approximately halfway between (A") and (C"), as shown in (B") in Figure 7. ”).Of course, this center value (reference value) and the adjustment range are not limited.

In an industry that provides audio devices, an equalizer device is provided when the speaker system is self-produced or when only the speaker system of the audio device shown in Patent Document 1 is commercialized.

1, 1', 1"... Speaker unit 101... Diaphragm 2, 2', 2"... Box 201, 201', 201"... Internal space 202 of box 2. ... Bass reflex duct 3 ... Acoustic resistance material 301 ... Surface 4 of acoustic resistance material 3 placed on the roadside in internal space 201 ... Partition wall 5 ... Sound source (signal generation) device 6 ... According to the present invention Equalizer device 601... Signal level adjustment 602... Amplifier circuit 603... Equalizer (CR filter) circuit 604... Buffer amplifier 605... BEF circuit 7... Amplifier (amplifier)

Claims (3)

It is a device that controls the frequency versus sound pressure characteristics of the bass range of a speaker unit that is responsible for the bass range, and where the relationship between frequency A and frequency B is A<B, the gain at the frequency of A is greater than the gain at frequencies equal to or higher than B. There is a relationship between frequency A and frequency B, where the gain changes at a rate of 6 dB/oct, and a BEF (band elimination filter) frequency centered at frequency C, where C<B. What is claimed is: 1. An acoustic equalizer device comprising a gain characteristic and a means for setting, selecting, or adjusting frequency A, frequency B, and frequency C uniquely based on the aperture of a target speaker unit. 2. The acoustic equalizer device according to claim 1, wherein said frequency A comprises means for adjusting the frequency. 3. The acoustic equalizer device according to claim 1, further comprising means for adjusting a gain at a frequency C of the BEF centered on the frequency C.

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