Acoustic equalizer device

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 Aa 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

[Technical field]

[0001] This invention belongs to an audio device and is used in an audio device in which the user prepares a speaker system and an amplifier separately and uses them in combination, and does not require any acoustic or electrical expertise regarding speakers or amplifiers. Shallow However, this invention relates to a device that can easily flatten, improve, and adjust the frequency characteristics of the low-frequency sound pressure generated from a speaker. [Background technology]

[0002] As the first background art, the patents obtained by the inventor of the present invention will be explained. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6699957

[0004] According to Patent Document 1, a speaker unit that mechanically suppresses resonance in the low frequency range using an acoustic resistance material made of an elastic material with small holes such as urethane foam or a flexible fiber material compressed at an appropriate density is installed in the box, and the sound pressure of the insufficient low frequency range is reduced by 0.5 of the speaker's lowest resonance frequency from the frequency where the sound pressure starts to become insufficient to lower frequencies. Double to The equalizer circuit has a frequency-to-gain characteristic that increases the gain by 6 dB / oct up to twice the normal level. Any low-frequency sound pressure that is still lacking after the equalizer circuit is compensated for by the resonance of the enclosure, for example, the bass reflex resonance of the bass reflex box. This allows the speaker system to achieve unprecedented low-frequency sound pressure, even with a small speaker unit and a speaker system that uses the speaker unit. Frequency Sound It is possible to construct an audio device capable of reproducing the above.

[0005] However, unless such audio equipment is provided as a set consisting of a speaker unit, a box, and an amplifier including an equalizer circuit as part of a complete, integrated product, such as a television or radio receiver, it will not provide sufficient performance for general users without specialized knowledge.

[0006] In addition, even in the case of audio equipment in which speaker systems, amplifiers, CD players, and other devices are provided separately and users combine them according to their personal preferences, unless at least a speaker system incorporating the above-mentioned mechanically resonance-suppressing speaker unit and an equalizer device that corrects the lack of low-frequency sound pressure for the speaker system are provided as a set, it is not possible to guarantee uniform reproduction sound pressure from low to high frequencies.

[0007] This is because the correction characteristics of the correction circuit must be adjusted according to the specifications of the speaker unit of the speaker system used for bass, the box in which it is installed, the degree of resonance suppression, etc., and adjustment of the correction characteristics can only be done by someone with specialized knowledge and the skills to use appropriate measuring equipment.

[0008] On the other hand, it is also available to the general public who do not have specialized knowledge or skills. ,A speaker enthusiast who builds his own speaker system by referring to the published construction examples and manuals, and purchasing speaker units and box boards as parts. The layer called It exists.

[0009] However, even such so-called DIY enthusiasts are not familiar with the creation of equalizers or correction characteristics that effectively flatten the frequency vs. sound pressure characteristics in the low-frequency range for the audio equipment in Patent Document 1 for the reasons mentioned above. Matching is considered difficult.

[0010] The second background art is a well-known technology not based on Patent Document 1, namely, a technology that uses resonance Normal speaker unit without suppressionThere are speaker systems that use a speaker box, i.e. a general bass reflex speaker system, and a general sealed speaker system.

[0011] They are used in combination with an amplifier, but if the parameter design of the speaker unit and box is inappropriate and the frequency vs. sound pressure characteristics in the low-frequency range are undesirable, it is possible to improve the characteristics by using a frequency vs. gain characteristic adjustment device such as a graphic equalizer on the amplifier side. In that case, too, the appropriate expertise and measuring equipment are required. Technology If not, it will be difficult to respond. Furthermore, it takes a considerable amount of time to respond to such cases. Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, the present invention relates to a bass-reflex speaker system using a speaker unit that suppresses low-frequency resonance of the speaker unit, and other conventional general bass-reflex or Closed speaker system This book is easy to understand for DIY enthusiasts with little acoustic and electrical expertise, and even for those who are not enthusiasts but want to try building a speaker system for the first time by purchasing a speaker unit and box building kit. The speaker system emits Bass Frequencies Sound pressure characteristics The objective of the present invention is to provide an acoustic equalizer device that can flatten and improve the sound quality.

[0013] Also, Expertise and skills Even for those with Easily Bass Frequencies Sound pressure characteristics The objective of the present invention is to provide an acoustic equalizer device that can flatten and improve the sound quality. [Means for solving the problem]

[0014] In order to solve the above problem, claim 1 states: Speaker unitAn apparatus for controlling the frequency - to - sound - pressure characteristics in the low - frequency range, having a frequency - to - gain characteristic such that at frequencies A and B where A < B, the gain at frequency A > the gain at frequencies of B or higher, and the gain changes at 6 dB / oct between frequency A and frequency B, and having a frequency - to - gain characteristic of a BEF (band - elimination filter) centered on a frequency C where C < B, and the frequencies A, B, and C are provided with means for being uniquely set, selected, or adjusted from the diameter of the target speaker unit. It provides an acoustic equalizer device characterized by this.

[0015] In order to solve the above - mentioned problems, claim 2 provides an acoustic equalizer device characterized by comprising means for adjusting the gain at frequency C of the BEF centered on the frequency C. Claim 1

Effect of the Invention

[0016] Accordingly, in claim 1, without knowing the values of frequencies A, B, and C determined from the specifications of the speaker unit and box used in the speaker system, the frequencies A, B, and C of the acoustic equalizer device can be appropriately set only from the diameter information of the speaker unit and specialized knowledge, thereby easily improving the frequency - to - sound - pressure characteristics in the low - frequency range of the speaker system. With or without measurement technology

[0017] Claim 2 provides Depending on the degree of suppression of mechanical resonance of the speaker unit the ability to finely adjust the peaks and valleys of the sound pressure at frequency C. Furthermore, even in speaker systems that use speaker units that do not suppress mechanical resonance, the frequency-to-sound pressure characteristics in the low-frequency range can be easily improved.

Brief Description of the Drawings

[0018] [Figure 1] A diagram showing an embodiment of the speaker system of Patent Document 1 [Diagram 2] A diagram showing the frequency - to - sound - pressure characteristics of the speaker system shown in FIG. 1 [Diagram 3] ​​FIG. 2 is a block diagram showing the configuration of an electric circuit device for driving the speaker system shown in FIG. [Figure 4] FIG. 1 is a diagram showing an embodiment of a circuit of an equalizer device according to the present invention. [Diagram 5] FIG. 5 is a diagram showing the frequency vs. gain characteristic of the equalizer circuit 603 shown in FIG. 4. [Figure 6] FIG. 6 is a diagram showing the frequency vs. sound pressure characteristic when the frequency vs. sound pressure characteristic shown in FIG. 2 is corrected by the frequency vs. gain characteristic shown in FIG. 5. [Figure 7] FIG. 5 is a diagram showing the frequency vs. gain characteristic of the BEF circuit 605 shown in FIG. [Figure 8] FIG. 8 is a diagram showing the frequency vs. sound pressure characteristic when the frequency vs. sound pressure characteristic shown in FIG. 6 is corrected by the frequency vs. gain characteristic shown in FIG. 7. [Figure 9] FIG. 5 is a diagram showing another embodiment of the circuit of the equalizer device shown in FIG. 4. [Figure 10] FIG. 10 is a diagram showing another embodiment of the circuit of the equalizer device shown in FIG. 4 and FIG. 9. [Figure 11] FIG. 1 shows an example of a typical bass reflex speaker system. [Figure 12] A diagram showing the frequency vs. sound pressure characteristics when a valley in sound pressure occurs between the resonance frequency due to the speaker unit and the volume of the internal space of the box in the bass-reflex speaker system of Figure 11, and the bass-reflex resonance frequency due to the bass-reflex duct and the volume of the internal space of the box. [Figure 13] FIG. 13 is a diagram showing the frequency vs. sound pressure characteristic when the frequency vs. sound pressure characteristic of FIG. 12 is corrected by the frequency vs. gain characteristic shown in FIG. 5. [Figure 14] FIG. 14 is a diagram showing the frequency vs. sound pressure characteristic when the frequency vs. sound pressure characteristic of FIG. 13 is corrected by the frequency vs. gain characteristic shown in FIG. 7. [Figure 15] FIG. 15 shows the frequency vs. sound pressure characteristic when the strength of the bass reflex resonance is adjusted appropriately in the frequency vs. sound pressure characteristic of FIG. 14. [Figure 16] FIG. 1 shows an example of a typical closed speaker system. [Figure 17] FIG. 17 is a diagram showing the frequency vs. sound pressure characteristic of the speaker system shown in FIG. 16. [Figure 18]FIG. 18 is a diagram showing the frequency vs. sound pressure characteristic when the frequency vs. sound pressure characteristic of FIG. 17 is corrected by the frequency vs. gain characteristic of FIG. 5. [Figure 19] FIG. 19 is a diagram showing the frequency vs. sound pressure characteristic when the frequency vs. sound pressure characteristic of FIG. 18 is corrected by the frequency vs. gain characteristic of FIG. 7. [Figure 20] A diagram showing the frequency vs. sound pressure characteristics when the volume of the box's internal space is set incorrectly for the speaker unit specifications in the speaker system shown in Figure 16, causing a peak in the sound pressure. [Figure 21] FIG. 18 is a diagram showing the frequency vs. sound pressure characteristic when the frequency vs. sound pressure characteristic of FIG. 17 is corrected by the frequency vs. gain characteristic of FIG. 5. [Figure 22] FIG. 19 is a diagram showing the frequency vs. sound pressure characteristic when the frequency vs. sound pressure characteristic of FIG. 18 is corrected by the frequency vs. gain characteristic of FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] First, an embodiment of the equalizer device of the present invention will be described based on Patent Document 1, in which a speaker unit with mechanical resonance suppression is applied to a bass reflex speaker system.

[0020] 1 is an explanatory diagram of one embodiment in which a speaker unit 1 with mechanical resonance suppression is attached to a bass reflex box 2, in which an acoustic resistance material 3 is disposed on the box internal space 201 side of the diaphragm 101 of the speaker unit 1, and the acoustic resistance material 3 is covered with a partition wall 4 so that only a part of its surface 301 is exposed to the box internal space 201, and the air vibration caused by the diaphragm 101 is transmitted to the box internal space 201 only through the surface 301 of the acoustic resistance material 3 by the partition wall 4. A bass reflex duct 202 is also provided in the box 2.

[0021] In addition, claim 3 of Patent Document 1 states that the resonance means of the enclosure is "due to a combination of the equivalent mechanical stiffness of the main space of the enclosure and an equivalent mechanical mass established separately," and although it is not limited to a bass reflex type box as explained in the present patent, a bass reflex type box will be used for explanation as a representative type.

[0022] Also, Fig. 1 corresponds to the embodiment of Fig. 24 in Patent Document 1, but the "mechanical resonance suppression means by damping the vibration of the diaphragm of the speaker unit" in claim 1 of Patent Document 1 corresponds to the sound absorbing materials 23 and 24 in Fig. 24 of Patent Document 1, and the acoustic resistance material 3 in Fig. 1 of the present patent. Furthermore, in claim 2 of Patent Document 1, "the mechanical resonance suppression means includes the rear surface of the diaphragm of the speaker unit and an opening at a predetermined distance from the rear surface of the diaphragm, and an acoustic resistance material having breathability and sound absorption is arranged between the diaphragm and the opening in a small space in which air vibration caused by the vibration of the diaphragm is transmitted to the main space inside the enclosure only through the opening" corresponds to the sound absorbing materials 23 and 24 arranged in the wall 20 constituting the small space and the opening 2101 of the small space in Fig. 24 of Patent Document 1, but in Fig. 1 of the present patent, the acoustic resistance material 3 is structured to be covered with a partition wall 4 leaving its surface 301.

[0023] Fig. 2 shows the frequency vs. 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. 1 (0.5 of fo in Patent Document 1). Double to 2 times), and frequency B is the fo of the speaker unit used. Resonance suppressed frequency C is the resonance frequency of the speaker unit 1 and the box internal space 201 when the speaker unit 1 is attached to the box 2; frequency D is the resonance frequency of the box internal space 201 and the bass reflex duct 202; and empirically these are set to approximately 1 / 2 of fo.

[0024] In Figure 2, (i) shows the frequency-to-sound pressure characteristics when the resonance of the speaker unit 1 is completely suppressed by the acoustic resistance material 3. Starting from frequency B, which is parameterized by the diameter of the speaker unit described later, the sound pressure decreases at 6 dB / oct towards lower frequencies. However, at frequency A, the decrease stops due to the overlap of the sound pressure peak (ii) caused by the bass reflex resonance of the bass reflex duct 202 and the box internal space 201, centered at frequency D.

[0025] (C) shows the frequency-to-sound pressure characteristics when the acoustic resistance material 3 is omitted and the resonance of the speaker unit 1 is not suppressed, in which the sound pressure is almost constant at frequencies above the resonance frequency C determined by the volume of the internal space 201 of the speaker unit 1 and the box 2, and below frequency C the sound pressure theoretically decreases at 12 dB / oct towards lower frequencies.

[0026] Here, the resonance of the speaker unit 1 is equal to the resonance of the 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 rises above fo. That resonance frequency is frequency C in Figure 2. To explain this in yet another way, the acoustic resistance material 3 in Figure 1 suppresses the mechanical resonance of the speaker unit 1, but this resonance suppression is the suppression of resonance caused by the internal space 201 of the speaker unit 1 and the box 2.

[0027] (B) is the frequency vs. 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 approaches the characteristics of (A) or (C) depending on the degree of resonance suppression.

[0028] Figure 3 shows the electrical circuitry that drives the speaker system shown in Figure 1. Device In the block diagram, 5 is a well-known sound source device such as a CD player, 6 is the equalizer device of the present invention, and 7 is a well-known power amplifier device (power amplifier) ​​connected to a speaker system.

[0029] Although not shown in Figure 3, devices commonly called preamplifiers or control amplifiers, which are used between 5 and 7 to select and switch the connection of sound source devices and recording devices, adjust volume, and adjust bass and treble levels (commonly known as tone control) in a different sense from the equalizer device of the present invention, are not shown in the figures and are well known in the art for the sake of convenience, but they are not necessary for the explanation of the present invention and are well known, so for the sake of convenience, they are not shown in the figures and are not explained in the explanation.

[0030] Figure 4 shows an embodiment of the detailed circuit of the equalizer device 6 of the present invention in Figure 3, which is composed of an analog circuit centered around an operational amplifier. In Figure 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 that attenuates gain within a frequency band.

[0031] In the figure, the processing order of the frequency vs. gain characteristics of the input signal is the equalizer circuit 603 and then the BEF circuit 605, but the order of the other amplifier circuits, buffer amplifiers, etc. can be changed as necessary.

[0032] Also, the basic circuits 602, 603, 604, and 605 are well known as operational amplifier and filter circuits, and we believe there is no need to explain their detailed operation again, but the frequency-gain characteristic of the equalizer circuit using CR 603 is such that the gain below frequency A is greater than the gain above frequency B, and the frequency between frequency A and frequency B changes at 6 dB / oct, as shown in Figure 5. For convenience of explanation, frequency A and frequency B in Figure 5 correspond to frequency A and frequency B in Figure 2 and are in the same relationship, but in reality, a slight deviation is allowed, as described later.

[0033] 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). In the circuit of this embodiment, C1 connected by SW1 is replaced by C11. ~By switching to C13, both frequency A and frequency B can be switched stepwise as a set, and frequency A can be adjusted with variable resistor r1 in R1, and frequency B can be adjusted with variable resistor r2 in R2. The reason for this will be explained later.

[0034] FIG. 6 is a diagram for explaining the correction effect of the equalizer circuit 603 on the frequency vs. sound pressure characteristic shown in FIG. 2. ~ The sound pressure characteristics of (D) are corrected as shown in Fig. 5 to obtain (A') ~ The sound pressure characteristics are as shown in (ii) and (iii).

[0035] When the frequency vs. gain characteristic shown in Figure 5 is used for correction, if the mechanical resonance suppression by the acoustic resistance material 3 is not complete, that is, if the characteristic before correction is (b) or (c) in Figure 2, after correction, In Figure 6 ,In contrast to the flat characteristic (a'), a peak in sound pressure appears at frequency C as shown in (b') and (c').

[0036] The BEF circuit 605 in Figure 4 is generally used in a device known as a graphic equalizer. In a typical graphic equalizer, the circuit section within the dotted frame is arranged in parallel for multiple bands of different center frequencies, for example 30, 60, 120, 250, 500...Hz, making it possible to reduce or increase the gain at the center frequencies.

[0037] The equalizer device of the present invention In this case, all that is needed is one band whose center frequency is C and whose gain can be set in a decreasing direction. For convenience of explanation, the center frequency C of the band is assumed to have the same relationship as the center frequency C of FIG. 2, but in reality, a slight deviation is allowed as described later. Also, the center frequency C of FIG. 7 can be adjusted by the variable resistor r3 in the figure. The gain is adjustable.

[0038] R3 and r3 are the same as in a normal graphic equalizer, but there is no R3 and only r3 (or the resistance of R3 is zero), and the slider (variable terminal) of r3 connected to C2 is at the midpoint of the resistance. At frequency C No change in gain (i.e. no increase or decrease in gain) ,From the slider in the figure under The resistance on the side is zero. At frequency CGain is minimum (gain attenuation is maximum), and the slider above The resistance on the side is zero Gain at frequency C is the maximum (or the increase in gain is the maximum), but in this invention, the resistance value of R3 is set to 0 (zero). ~ In the range up to r3 It is acceptable to set it as R3=r3. Preferably, R3=r3. In that case, when the slider is placed at the top of the diagram, the gain change at frequency C is zero, and when it is placed at the bottom, the gain is minimum (gain attenuation is maximum). In this specification, the resistance value of R3=r3 is described.

[0039] The center frequency C is determined by C2, C3, R4, and R5 in the figure. ( 2π√(C2C3R4R5) ) The formula is as follows: SW2 in the figure switches in stages in sets such as C21 and C31, C22 and C32, and C23 and C33. The reason for this will be explained later.

[0040] It should be noted that frequency C can be made adjustable just like frequency A and frequency B. In this case, it is conceivable to provide a variable resistor r5, but r5 is not an essential component.

[0041] As mentioned above, Fig. 7 shows the frequency-gain characteristics of the BEF circuit 605. The band center frequency C of the BEF is the same as the frequency C in Figs. 2 and 6 as mentioned above, and the bandwidth of the attenuation characteristics is appropriately set by the circuit constants so as to roughly correspond to the frequencies D and B in Fig. 6.

[0042] The degree of gain attenuation at center frequency C is adjusted by r3 in Figure 4 as mentioned above. The adjustment amount is The maximum difference in sound pressure between (Ha') and (I') at frequency C in Figure 6 degree Then, at the minimum, it is zero. Normally, the r3 slider is adjusted so that the degree of attenuation is halfway between maximum and minimum. In the following explanations, the adjustment position of the slider at this time will be considered as the central position of the gain adjustment. That is, The degree of damping can be adjusted from the normal middle to minimum or maximum with r3. The circuit constants are set so that (C") in Figure 7 is the inverse characteristic of the difference between (C') and (A') in Figure 6 (C'-A'), and (B") in Figure 7 is the inverse characteristic of the difference between (B') and (A') in Figure 6 (B'-A'). setting do.

[0043] The characteristic of (a) in Figure 7 shows zero gain attenuation, which is the result of setting R3 = r3 in the circuit diagram of Figure 4 and moving the slider of r3 to the above This is achieved by adjusting the camera to its fullest position.

[0044] Now, the equalizer device of the present invention is configured as described above, but a more detailed explanation is required regarding the relationship between the frequency A, frequency B, and frequency C in FIG. 2, which are the frequency vs. sound pressure characteristics of the speaker system, and the switching of SW1 and SW2 in FIG. 4. In fact, in a speaker system configured as shown in FIG. 1, the frequencies A, B, and C in FIG. 2 are roughly the same depending on the diameter of the speaker used. Representative value is determined In the equalizer device, the representative values ​​for frequencies A, B, and C in Fig. 7 are used for each aperture. If you want to have an adjustment range, use the representative value as the center value. There is no problem with that.

[0045] To explain this in terms of frequency B, first, the frequency B is approximately 1000Hz for a speaker with a nominal diameter of 10cm, and approximately 500Hz for a speaker with a nominal diameter of 20cm. This is because the equation Ka=2πa / λ (a: radius of the disk, λ: wavelength) is generally known as the relational expression that expresses the radiation impedance of a disk, and when Ka is 1 or less, the effective radiation impedance decreases, and when the diaphragm vibrates with the same amplitude, the sound pressure decreases in proportion to the decrease in impedance. This is because the frequency at which Ka becomes 1 is approximately 1000Hz for a disk with a diameter of 10cm (radius a ≒ 5cm), and approximately 500Hz for a diameter of 20cm (radius a ≒ 10cm). In reality, even if the nominal diameter of speaker units on the market is the same, the radius of the diaphragm varies slightly from product to product, and frequency B also varies slightly, but generally, frequency B is uniquely determined by the diameter of the speaker used, and If you want to have an adjustment range, use the representative value as the center value. It is also acceptable.

[0046] Next, frequency A is set at 0.5 of the speaker unit fo as mentioned above. Double to We consider the range to be 2 times that of the frequency B, but for speaker units currently on the market, this fo is similar to frequency B, depending on the diameter. For example, for a 10 cm speaker unit, it is approximately 80 Hz, and for a 12 cm speaker unit, it is approximately 80 Hz. cm~ 50 for a 16cm caliber Hz to 70Hz, and 40Hz for the 20cm diameter. every(It is a product that has been marketed with sufficient consideration given to bass reproduction for audio use.) For DIY use (This is for the most commonly used speakers.) Therefore, frequency A is determined by the diameter of the speaker unit used. The average fo is in the range of 0.5 to 2 times that. A representative value is uniquely determined, If you want to have an adjustment range, use the representative value as the center value. It is also acceptable.

[0047] Furthermore, the frequency C also varies depending on the diameter of the speaker unit used, for example, the frequency C is approximately 1.5 times the fo of the speaker unit used at 10 cm and approximately 2 times at 20 cm. A representative value may be set.

[0048] This is the first prior art As explained In Patent Document 1, the resonance frequency of the bass reflex duct of the bass reflex box, i.e., frequency D, is empirically set to about 1 / 2 of the fo of the speaker unit to be used. The resonance frequency of the bass reflex duct at this time is calculated from the cross-sectional area and length of the duct and the internal volume of the box. Therefore, once the desired bass reflex resonance frequency is determined for each diameter of the speaker unit, a practical duct cross-sectional area and length can be determined. By setting Naturally, the internal volume of the box will be similar. This is because it will be consolidated.

[0049] Furthermore, the size of the speaker unit used In terms of external dimensions In the box On the other hand It must be possible to install it with a reasonable degree of fit, and these two constraints dictate that the reasonable and practical internal volume of the box is concentrated within a certain range for each diameter of the speaker unit.

[0050] For example, when the speaker unit has a diameter of 10 cm and the frequency is 80 Hz, the design of the internal volume of the box is 3L according to the above constraints. ~ The design is concentrated in the range of about 10L. In this case, the resonance frequency C of the speaker unit and the internal space of the box is By a formula not shown, At 3L it is about 130Hz (about 1.6 times fo), at 5L it is about 110Hz (about 1.4 times fo), at 10L it is about 100Hz (about 1.3 times fo) It is calculatedThe magnification of the resonant frequency C to fo is approximately 1.5 times (120Hz). unambiguously Set as a representative value, If you want to have an adjustment range, use the representative value as the center value. That's fine.

[0051] Similarly, when the speaker unit is 20 cm in diameter and the frequency is 40 Hz, the internal volume of the box is 15 L for the same reason as in the case of the 10 cm diameter. ~ In most cases, the design is concentrated in the range of about 40L. In this case, the resonance frequency C of the speaker unit and the internal space of the box is 100Hz (about 2.5 times fo) at 15L, 80Hz (about 2 times fo) at 20L, and 65Hz (about 1.6 times fo) at 40L. The magnification of the resonance frequency C to fo is roughly twice (80Hz). unambiguously Set as a representative value, If you want to have an adjustment range, use the representative value as the center value. That's fine.

[0052] This indicates that in the explanation of frequency C above, there is a slight frequency shift between the frequency C on the equalizer side using a representative value and the actual frequency C on the speaker system side, but if we examine the effect of this shift on the frequency vs. sound pressure characteristics, we find that when the ratio of frequency C on the speaker system side to frequency C on the equalizer device side, i.e. (frequency C on the speaker system side) / (frequency C on the equalizer device side), is 0.5 or 2, a sound pressure step of up to 6 dB occurs in the vicinity of frequency C in the frequency vs. sound pressure characteristics. This is because the sound pressure difference between the characteristics (C) and (A) in Figure 6 is 6 dB / oct except at the position of frequency C, and the sound pressure difference when the frequency changes by a factor of two is 6 dB.

[0053] However, among the several cases mentioned above, the worst condition where the ratio of (speaker system frequency C) / (equalizer device frequency C) is maximum is when the speaker diameter is 20 cm and the box volume is 15 L, and the ratio is 100Hz / 80Hz= The effect on sound pressure in this case is only 1 / 4 of 6 dB, i.e., a sound pressure step of 1.5 dB appears near frequency C. The frequency vs. sound pressure characteristics of speaker systems actually on the market are within ±6 dB within their reproducible frequency range. B~A 10 dB bump is normal and within the normal range, so a 1.5 dB sound pressure difference is not that big. Therefore, there is no problem if there is a slight frequency difference between the actual frequency C of the speaker system and the frequency C of the equalizer, which is determined by its representative value.

[0054] For the same reason, it is acceptable to use representative values ​​for each diameter of the speaker unit used on the equalizer side for frequencies A and B. Median value and The reason for the replacement is that frequency A, frequency B, and frequency C are considered to have adjustment means by r1, r2, and r5 in addition to switching between SW1 and SW2. Centered on range Set a position and adjust it when it is in that position. Frequency This is because it is assumed that the value is a representative value. Due to the difference between the typical value and the actual frequency as explained in Frequency C It goes without saying that this eliminates sound pressure differences.

[0055] From the above, frequencies A, B, and C can be uniquely determined by the diameter of the speaker unit used. Set the representative value It is possible.

[0056] Therefore, in the equalizer device of the present invention, for example, a changeover switch indicating the diameter of the speaker unit to be used is provided in the equalizer device, and the equalizer device changes the frequencies A, B, and C according to the changeover position of the switch. Switch to the representative value or the central value In this way, the user can set the equalizer switch to the size of the speaker unit being used. At the display position of By simply switching between these settings, you can set each frequency appropriately without needing to know frequency A, frequency B, or frequency C, which should actually be set through calculations or experiments based on the specifications of the speaker unit, box size, etc.

[0057] In the embodiment of the present invention, SW1 and SW2 correspond to the changeover switches according to the diameter of the speaker unit. The circuit example in FIG. 4 shows only the circuit of one side CH, L or R, of both LR stereo CHs, and only for one side circuit, SW1 needs a 1-circuit 3-contact switch, and SW2 needs a 2-circuit 3-contact switch. Therefore, in order to switch and select both LR CHs at once, SW1 needs a 2-circuit 3-contact switch, and SW2 needs a 4-circuit 3-contact switch. These SW1 and SW2 may be independent, or may be combined into one with 6 circuits and 3 contacts. SW2 may also be provided separately on the C2 side and the C3 side, and there is no problem as long as the switching position can be specified by the diameter of the speaker unit. The number of contacts can be increased or decreased according to the type of diameter of the speaker unit to be applied.

[0058] Furthermore, the switch position on the surface of the equalizer device is indicated only by symbols and frequency notation, and the instruction manual etc. shows the correspondence between the diameter of the speaker unit and the switch position, i.e., the symbols and frequencies, in a table. Frequency A, frequency B, and frequency C can be set and selected uniquely from the aperture information.

[0059] In the equalizer device of the present invention as described above, when the diameter of the speaker unit to be used is selected by switching SW1 and SW2, and the frequency A, frequency B, and frequency C are switched internally according to the diameter of the speaker unit, as described above, the frequency vs. sound pressure characteristic of the original speaker system shown in FIG. 2 becomes (a') between frequency D and frequency B in FIG. 6 due to the frequency vs. gain characteristic of the equalizer circuit 603 shown in FIG. 5. ~ It will be in the range of (Ha').

[0060] Next, between frequency D and frequency B in Figure 6 is (a'). ~ When the frequency vs. sound pressure characteristic is in the range of (c'), the frequency vs. gain characteristic of the BEF circuit 605 shown in FIG. 7 is corrected to the frequency vs. sound pressure characteristic of FIG. 8. will explain the details.

[0061] If the acoustic resistance material 3 of the speaker system shown in Figure 1 does not completely suppress the mechanical resonance of the speaker unit 1, and the frequency vs. sound pressure characteristic shown in Figure 2 is as (b) and this characteristic is centered between (a) and (c), then by setting the slider r3 of the BEF circuit 605 to the center position for gain adjustment, the sound pressure peak (b') at frequency C in the frequency vs. sound pressure characteristic shown in Figure 6 can be flattened as shown in Figure 8 (a) by simply switching between SW1 and SW2.

[0062] If the mechanical resonance of the speaker unit 1 by the acoustic resistance material 3 of the speaker system shown in FIG. 1 is nearly completely suppressed and the frequency vs. sound pressure characteristic shown in FIG. 2 is close to (I), then simply switching between SW1 and SW2 with the slider r3 of the BEF circuit 605 at the central position for gain adjustment will result in a sound pressure valley at frequency C in the frequency vs. sound pressure characteristic shown in FIG. 6, as shown in FIG. 8 (b). In that case, by adjusting the slider of r3 to adjust the frequency vs. gain characteristic in FIG. 7 toward the (I”) side, it is possible to approach (a).

[0063] Conversely, if the acoustic resistance material 3 of the speaker system shown in Figure 1 is barely effective in suppressing the mechanical resonance of the speaker unit 1 and the frequency vs. sound pressure characteristic shown in Figure 2 is close to (C), then simply switching between SW1 and SW2 with the slider r3 of the BEF circuit 605 at the central gain adjustment position will result in a sound pressure peak (C') at frequency C in the frequency vs. sound pressure characteristic shown in Figure 6, as shown in Figure 8 (c). In that case, by adjusting r3 to adjust the frequency vs. gain characteristic in Figure 7 towards the (C") side, it is possible to bring it closer to (a).

[0064] This adjustment can be done precisely using measuring instruments, but Regardless of frequency characteristics Simply by hearing the musical tones To the adjuster To make it sound good You may go .

[0065] The reason why such adjustment is necessary is that in practical mechanical resonance suppression, the frequency vs. sound pressure characteristic must be located between characteristic curves (C) and (A) as shown in Figure 2 (B), and the degree of suppression varies depending on the speaker unit and acoustic resistance material used, as well as the degree of compression of the acoustic resistance material, and therefore the position between (C) and (A) cannot be limited. Therefore, this adjustment is essential if you want to precisely flatten the frequency vs. sound pressure characteristics. This is because, if the resonance could be completely suppressed, such adjustments would not be necessary, but to completely suppress the resonance, the air flow going back and forth inside the acoustic resistance material must be suppressed to the extent that the vibration of the diaphragm of the speaker unit is stopped. Original drive electrical signal It also suppresses the vibration of the diaphragm and the important sound generation, so mechanical resonance suppression is naturally Limitations arise It has to be half-hearted.

[0066] Here, the characteristic shown in Figure 2 (c) is the frequency vs. sound pressure characteristic when no mechanical resonance suppression is implemented in the speaker unit using acoustic resistive material, in which the sound pressure remains almost constant from frequency B to the resonance frequency C determined by the speaker unit and the internal spatial volume of the box, and from frequency C onwards the sound pressure decreases at a slope of 12 dB / oct.

[0067] Therefore, the gain at the center frequency C of the BEF circuit of 605 in Figure 4 is approximately equal to the sound pressure difference between (C) and (A) at frequency C in Figure 2. As 1 / 2 ,If you can adjust the remaining ±1 / 2, For speaker units Realistic mechanical resonance suppression Lecture and production Depending on the degree of mechanical resonance suppression of the speaker system, adjust the remaining ±1 / 2 to accurately match the characteristics of (a). This makes it possible.

[0068] This means that First Conventional technology explanation Even in a speaker system that is constructed without the mechanical resonance suppression means using the acoustic resistance material 3 from the configuration requirements of Patent Document 1, the mechanical resonance can be suppressed by adjusting the gain at the center frequency C of the BEF circuit of 605. The speaker system of the patent that was suppressed This suggests that it is possible to construct a small audio device with similar bass reproduction capabilities.

[0069] That is, as explained in Figure 2, the frequency of the bass reflex resonance of the bass reflex box is set to about 1 / 2 of the fo of the speaker unit, and then the frequency A is set to 1 times the fo of the speaker unit to be used, with 0.5 as the base. Double to By adjusting the volume to about twice the volume, it is possible to suppress mechanical resonance without using the acoustic resistance material 3. By using the equalizer device of the present invention It is possible to obtain a small acoustic device capable of reproducing a frequency approximately half the fo of the speaker unit used.

[0070] However, in this case, the diaphragm and the space inside the box are connected without any acoustic resistance material. Therefore, when the box is constructed as a parallelepiped, the resonance generated according to the distance between the parallel walls inside the box is transmitted directly to the diaphragm, and the resonance sound is transmitted from the diaphragm to the space outside the speaker system. In other words, the resonance sound, known as box resonance, is easily emitted outside the box. cannot be resolved.

[0071] As mentioned above Adjustment of frequency A and frequency B can be done by adjusting the frequency to the optimum point using a measuring tool, simply In the user's opinion The user feels that it is pleasant to listen to. To adjust the position It may be used. The same applies when an adjustment means is provided for frequency C.

[0072] Adjustment of frequency A and frequency B is The adjustment range It is possible to set the frequency at adjacent switching positions by SW1 so that it can cover continuously. For example, in adjusting frequency A, when the switching by SW1 indicates 10cm, 13cm, and 20cm in diameter, and frequency A is set with a central value of 80Hz at the 10cm position and 60Hz at the 13cm position, if the adjustment at the 10cm position is configured so that the minimum adjustment is approximately 10Hz on the negative frequency side, and the adjustment at the 13cm position is configured so that the minimum adjustment is approximately 10Hz on the positive frequency side, frequency A can be adjusted almost continuously between the 10cm and 13cm diameters. The same applies between 13cm and 20cm.

[0073] Furthermore, the adjustment of frequency A is The median value It is very preferable to configure the fo so that it can be adjusted to about 1 / 2 to 2 times the fo. This is because, in Patent Document 1, the frequency A is set to 0.5 of the fo of the speaker unit used. Double to It is doubled So ,The central value of the adjustment is set to 1 times fo, and the adjustment range is set to 0.5 times the central value on the negative side. ~ 1x, plus 1x ~ If you can adjust it to 2 times and set it to the center value at all times, you can first set it to the fo of the speaker unit you are using by simply switching SW1, and then adjust it to a maximum of 0.5 times on the negative side and a maximum of 2 times on the positive side for each diameter. This makes it ideal as the equalizer device of Patent Document 1.

[0074] As mentioned above, the resonance frequency D of the bass reflex duct and the internal space of the box should basically be set to about half the fo of the speaker unit being used, but for speaker units with a diameter of about 5 cm, fo is about 200 Hz. From experience with prototypes of such speaker units, it has been shown that the frequency vs. sound pressure characteristics can be successfully flattened by setting the resonance frequency D to 70 Hz and adjusting frequency A to around 130 Hz.

[0075] In this experiment, frequency D is 0.35 times the fo of the speaker unit used, and frequency A is 0.65 times the fo. This frequency A is 0.5 times fo ~ It is adjustable with a range setting of 1x.

[0076] In addition, when using a speaker unit with a diameter of 10 cm and fo of 80 Hz, it has been possible to adjust the frequency D to 40 Hz and the frequency A to around 160 Hz to achieve a flat frequency vs. sound pressure characteristic. In this case, the frequency D is 1 / 2 the fo of the speaker unit, and the frequency A is twice the fo, This frequency A is 1x fo The positive side i.e. 1x ~ It can be adjusted over a double range setting. In this way, adjustment of frequency A can be used.

[0077] On the other hand, the adjustment range of frequency B does not need to be as wide as that of frequency A because, as mentioned above, frequency B is a unique value calculated from the diameter of the speaker unit's diaphragm. However, it is calculated for each diameter. To the center value On the other hand, the maximum negative side is 0.5 times ~ 1x. The positive side is 1x ~ I think a 1.5x adjustment would be sufficient.

[0078] This adjustment function, which is a repetition of what has already been mentioned, is r1 and r2 for frequency A and frequency B, and r3 for frequency C. r5 Adjustment position first If the center point of the adjustment range is set as the representative value and r3 is set as the center position of the gain adjustment, By simply switching SW1 and SW2, you can operate the device without any special knowledge or experience. Lack of measurement technology Even for those who are not familiar with the technology, the frequency A, frequency B, and frequency C can be set appropriately. This can flatten and improve the frequency vs. sound pressure characteristics. In addition to the advantages of this, the size of the speaker unit used, the degree of mechanical resonance suppression, the volume of the box, the resonance frequency of the duct, etc. Adjustment of frequency A, frequency B, and frequency C Related Device Instruction Manual etc. If you write it down, your expertise and Those with measurement techniques will be able to make more precise adjustments to frequencies A, B, and C in relation to the frequency-sound pressure characteristics, and furthermore, regardless of the presence or absence of knowledge or technique, or whether the frequency-sound pressure characteristics are flattened or improved, the adjuster will be able to make adjustments that they feel are more preferable based solely on their hearing.

[0079] Figure 9 shows an embodiment of an equalizer device circuit different from that shown in Figure 4. The difference between Figure 9 and Figure 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, and the frequency can be changed continuously by simply using the entire R1 and the entire R2 as variable resistors, or it is also possible to switch in stages.

[0080] When R1 and R2 are switched continuously, the change of frequency A and frequency B is not a point-by-point change, but the diameter of the speaker unit or the position of the knob of the variable resistor at the position where the resistance of R1 and R2 becomes the required resistance value is indicated. Related to caliber If you set it to display symbols, it can be treated the same as a switching switch.

[0081] In this case, R1 and R2 change continuously, and therefore frequency A and frequency B also change continuously by adjusting R1 and R2. However, frequency A = 1 / (2π(R1+R2)C1) and frequency B = 1 / (2πR2C1), so when C1 is a fixed value, frequency A is determined by the value of (R1+R2), and frequency B is determined by the value of R2.

[0082] Therefore, first, the knob position of R2 is indicated at the resistance value where frequency B is the representative value, then the resistance value when the knob is set to the display position of each caliber is substituted for R2 in (R1+R2) where frequency A of each caliber is the representative value, and the remaining R1 is indicated at the knob position where the resistance value required to set the representative value of each caliber is displayed with the caliber or caliber-related symbol, then the representative values ​​of frequency A and frequency B can be set by adjusting R1 and R2. Moreover, since the relationship between frequency A and frequency B is frequency A<<frequency B, the relationship between R1 and R2 is R1>>R2, and frequency A mainly depends on the value of R1, so the knob position of R2 does not need to strictly match the display position of the caliber.

[0083] As another method, as shown in FIG. 10, a set of C1, C2, and C3 (C2 & C3) can be configured as plug-in parts, and multiple types of plug-in parts can be provided for each diameter of the speaker unit. If the plug-in parts can be interchangeably connected on the equalizer device side, the user can easily but By selecting plug-in parts according to the diameter of the speaker unit and connecting them to the equalizer device, you can set frequencies A, B, and C. unambiguously Set it up properly can .

[0084] Yet another method is to C1, C2, C3 are switched or selection The frequency A, frequency B, and frequency C of the equalizer device are the only types. The value is fixed to a representative value determined uniquely from the diameter of the The equalizer device itself is configured according to the diameter of the speaker unit, this one for a 10 cm diameter and this one for a 20 cm diameter. Provide Good too. This method also makes it possible to set frequencies A, B, and C uniquely according to the diameter of the speaker unit.

[0085] Next, in the second prior art explanation This paper explains the improvement in frequency-to-sound pressure characteristics using the equalizer device of the present invention for a typical bass reflex speaker system in which a speaker unit that does not suppress mechanical resonance is combined with a bass reflex box, and for a typical closed speaker system in which a speaker unit that does not suppress mechanical resonance is combined with a closed box.

[0086] FIG. 11 shows the second prior art. Explained in ,General bass reflex speaker system Structure of FIG. 12 is a diagram illustrating the frequency vs. sound pressure characteristics of a case where the design failed.

[0087] This failure example occurs when, in the design of a typical bass reflex box, the resonant frequency (frequency D') of the bass reflex duct 202' is set too low compared to the resonant frequency (frequency C') of the speaker unit 1' and bass reflex box 2' in Figure 11, resulting in a sound pressure valley between frequency C' and frequency D' in the composite sound pressure characteristic (G) of the sound pressure characteristic (E) not taking into account the bass reflex duct and the sound pressure characteristic (F) of the bass reflex duct in Figure 12.

[0088] In such a case, when using the equalizer device of the present invention to improve the frequency-to-sound pressure characteristics, first connect the equalizer device of the present invention to the position shown in Figure 3, then set SW1 and SW2 to the aperture of the speaker unit. At that time, frequency A is At the median Leave it as it is. Next, adjust the gain adjustment for frequency C to minimum gain (maximum gain reduction). After that, stuff glass wool or other acoustically resistive material into the bass reflex duct to adjust the degree of bass reflex resonance, while adjusting frequency A and adjusting the overall sound pressure balance by ear or with a measuring device.

[0089] This adjustment is shown in Figure 12. ~ This will be explained in detail using Figure 16. In Figure 12, the sound pressure characteristic (E) is such that, due to resonance between the speaker unit and the space inside the box, the sound pressure at the center frequency C' of the resonance is raised to the same level as the sound pressure at frequency B', and the sound pressure drops sharply at frequencies lower than the center frequency C'. It is generally said that the drop in sound pressure at frequencies lower than frequency C' occurs at a rate of 12 dB / oct.

[0090] Therefore, when the frequency interval between frequencies C' and D' is wide, the sound pressures at the overlapping parts of the sound pressure characteristics (E) and (F) are both low, so the composite sound pressure characteristic results in a valley in sound pressure between frequencies C' and D', as shown in (F).

[0091] When the equalizer device of the present invention is used, first, the frequency vs. sound pressure characteristics of the speaker system of 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 within the device.

[0092] In this case, frequency B' in Figure 12 depends almost entirely on the diameter of the speaker unit, as mentioned above. If the diameter is the same, frequency B in Figure 5 will also be the same, and even in a typical bass-reflex speaker system The present invention The equalizer device can be applied as is.

[0093] Next, the frequency vs. sound pressure characteristic of Fig. 13 is corrected as shown in Fig. 14 by the frequency vs. gain characteristic of the BEF circuit 605 of Fig. 4 shown in Fig. 7. At this time, the gain adjustment at the center frequency C by r3 of the BEF circuit 605 is set to the minimum gain (maximum gain reduction), so that the frequency vs. sound pressure characteristic of Fig. 6 is corrected as shown in Fig. ~ The same as the description of Figure 8 reason This makes it possible to flatten the peak of sound pressure at frequency C' in FIG.

[0094] As shown in Figure 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 mentioned above. This is because the fo of the speaker unit used varies slightly depending on the product, General Bass reflex box, First Conventional technology explanation The difference between the bass reflex box shown in Patent Document 1 and the one shown in Patent Document 2 is the concept behind the structure. This is because there is a difference in the setting of the internal space volume of the box.

[0095] The example in Figure 14 explains the case where frequency C is slightly higher than frequency C', but generally, the difference in resonant frequency between the speaker unit and the volume of the box's internal space due to differences in the volume of the box's internal space is only a few tens of percent, as mentioned above, and the resulting sound pressure difference between frequencies C and C' is only a few dB, so the mismatch between frequencies C' and C has almost no effect on the frequency-to-sound pressure characteristics, and the sound pressure peak at center frequency C' can be largely corrected by the BEF circuit at center frequency C.

[0096] In Figure 14, the peak sound pressure of the bass reflex resonance sound pressure (He') due to the bass reflex duct 202' and the box internal space 201' at center frequency D' is expected to be higher than the corrected sound pressure at frequency C' in Figure 14 due to the correction by the equalizer circuit 603 and BEF circuit 605 in Figure 4.

[0097] Therefore, if the sound pressure of the bass reflex resonance becomes higher than the corrected sound pressure at frequency C' as in Figure 14, it is necessary to lower this sound pressure peak appropriately. Figure 15 shows how this is done, by adjusting the sound pressure peak (F') at resonance frequency D' in Figure 14 to a weaker degree of resonance by filling bass reflex duct 202' in Figure 11 with an acoustically resistive material such as glass wool, and also adjusting frequency A to lower the height of the peak as shown (F"). This adjustment can also be done with a measuring instrument, or it can simply be adjusted appropriately by listening.

[0098] The above is Figure 11 ~ As explained in Figure 15, even in cases where there is a valley in sound pressure between frequency D' and frequency C' in a typical bass reflex speaker system as in Figure 12, it is relatively easy to use the equalizer device of the present invention to improve the situation to one where there is no valley in sound pressure as in Figure 15. If the equalizer of the present invention is not used, it would be necessary to change the speaker unit, redesign the box to lower the resonant frequency C', or shorten the duct length of the bass reflex duct to raise the resonant frequency D', or in any case redo the mechanical structure, equivalent It takes a lot of effort.

[0099] This is the effect of flattening out the mechanical resonance caused by the speaker unit with center frequency C' shown in Figure 12 and the internal space of the box using the electrical correction means BEF circuit 605 and equalizer circuit 603 shown in Figure 4, and reconstructing the characteristics, thereby improving only the characteristics without changing the mechanical structure.

[0100] Note that Figure 11 ~In the explanation of FIG. 15, adjustment of frequency B and frequency C was not explained, but it goes without saying that the correction can be made more precise and appropriate by making appropriate adjustments according to the situation.

[0101] From the above, although it is necessary to adjust the resonance degree of the bass reflex duct at frequency D' by using an acoustic resistance material or to adjust frequency A, in the case of a conventional bass reflex speaker system, if the parameter design fails, Not only can characteristics be improved using less-laborious electrical means without requiring labor-intensive physical changes such as changes to the box volume or the cross-sectional area or length of the duct, but improvements can also be easily achieved using the equalizer device of the present invention, which can uniquely set frequency A, frequency B, and frequency C from the diameter information of the speaker unit.

[0102] To put it the other way around, in a conventional general bass-reflex speaker system, even if the box internal volume is intentionally set smaller than normal, by using the equalizer device of the present invention, it is possible to obtain the same bass frequency reproduction capability as with the proper setting, and also, in a general bass-reflex speaker system with an internal volume properly set, by modifying the speaker system's bass-reflex duct to be longer and lowering the bass-reflex resonance frequency D', intentionally creating a valley in the frequency-to-sound pressure characteristics as shown in Figure 12, and then applying the equalizer device of the present invention there, it is possible to expand the bass reproduction frequency of a general bass-reflex speaker system at hand. This is the case in the first prior art patent where the speaker unit is not provided with a mechanical resonance suppression means using an acoustic resistance material. Similar .

[0103] FIG. 16 shows the second prior art. Explained in Closed box speaker system Structural diagram of FIG. 17 is a diagram illustrating the frequency vs. sound pressure characteristics.

[0104] In FIG. 17, frequency C'' is the resonant frequency of speaker unit 1'' and box internal volume 201'', and is theoretically higher than the fo of speaker unit 1''. However, if internal volume 201'' is appropriately selected for the fo and Q of speaker unit 1'', the sound pressure can be flattened at frequencies above frequency C'', as shown in FIG. 17.

[0105] 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 matched to the diameter of the speaker unit 1", first, due to the correction characteristics of the equalizer circuit 603 shown in FIG. 5, a sound pressure peak occurs at frequency C" in the frequency vs. sound pressure characteristics as shown in FIG. 18(h'), and then, due to the correction characteristics of the BEF circuit 605 shown in FIG. 7, the characteristics can be improved to a flat characteristic up to frequency A as shown in FIG. 19(h").

[0106] 18 and 19, as mentioned above, there is virtually no problem if frequency C'' is replaced with frequency C and frequency B'' is replaced with frequency B, so here the explanation will be given assuming C'' ≒ C, B'' = B.

[0107] In this case, by setting frequency A to be the same as or lower than the fo frequency of speaker unit 1", the limit of the low frequency that can be reproduced at the same sound pressure as the mid- and treble frequencies can be improved from frequency C", which is higher than the fo frequency of speaker unit 1", to frequency A, which is lower than the fo frequency. For example, when a speaker unit with a diameter of 10 cm and an fo of 80 Hz is installed in a 5 L sealed box, frequency C" will be around 120 Hz, but this can be improved to below 80 Hz.

[0108] Next, we will explain a case where the characteristics of a speaker system using the same sealed speaker box were improved by using the equalizer device of the present invention after a design failure. An example of the frequency vs. sound pressure characteristics in this case is shown in Figure 20. This example is a case where the specifications of speaker 1" and the box internal volume 201" were unreasonably selected for a typical sealed box, resulting in a bass frequency C" that was higher than the desired frequency and a peak in sound pressure centered around frequency C".

[0109] This type of situation occurs when the box size is designed to be smaller than the fo, diameter, diaphragm mass, and Q of the speaker unit being used, and is particularly likely to occur with speaker units that have a light diaphragm mass and a large Q.

[0110] In such a case, to improve the frequency-to-sound pressure characteristics using the equalizer device of the present invention, the negative (gain-reducing) adjustment range of the gain adjustment at frequency C of the BEF circuit 604 in Fig. 4 must be set wider than described above. This requires setting the circuit constants to increase the Q of the BEF resonant circuit accordingly, but this explanation is based on the assumption that the constants of the other CR elements, including C2, C3, R4, and R5 of the BEF circuit 605, have been set in such a way.

[0111] Connect such an equalizer device to the position shown in Figure 3, and first set SW1 and SW2 to the diameter of the speaker unit. Then adjust each frequency as follows: center position Leave it as it is. Next, adjust the gain adjustment for frequency C to the maximum negative side.

[0112] Regarding this, Figure 20 ~ This will be explained in detail using FIG. 22, but in conclusion, the gain adjustment range at frequency C of the BEF circuit of the equalizer device has been expanded to the negative side, and the gain adjustment range is the same as in FIG. 17. ~ This is the same as in the case of FIG.

[0113] In Figure 20, the sound pressure characteristics (h) are such that the sound pressure at center frequency C'' is raised to a level higher than the sound pressure at frequency B'' due to resonance between speaker unit 1'' and the box internal space 201'', and the sound pressure drops sharply at frequencies lower than center frequency C''.

[0114] If the equalizer device of the present invention is used in this, first, due to the correction characteristics shown in FIG. 5 of the equalizer circuit 603 in FIG. 4 within the device, the frequency vs. sound pressure characteristics will be as shown in FIG.

[0115] Next, the frequency vs. sound pressure characteristic of FIG. 21 is corrected as shown in FIG. 22 by the correction characteristic of the BEF circuit 605 of FIG.

[0116] 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 it can also improve the peak in sound pressure in the bass range that occurs when the speaker unit and box volume are not properly set.

[0117] In the above, the center values ​​of frequency A, frequency B, and frequency C are merely examples, and the settings and switching can be performed based only on the diameter information of the applicable speaker. Adjustment operation If it is possible to do so, it is considered to be within the scope of the rights.

[0118] In addition, while the description of the embodiments shows that the equalizer device is composed of an analog circuit, the scope of the rights also includes a digital filter using a computer system in which the settings for frequency A, frequency B, and frequency C can be made based on the diameter information of the applicable speaker unit.

[0119] To summarize the above explanation, the acoustic equalizer device of the present invention sets the frequencies A, B, and C of the equalizer device to representative values ​​uniquely based on the diameter of the speaker unit used. setting, choice, Or adjustment operation Therefore, even if there is a slight difference between the frequencies A, B, and C of the equalizer device and the frequencies A, B, and C strictly required for the speaker system using the speaker unit, the user can easily adjust the frequency of the speaker unit to be used without knowing the required frequencies A, B, and C. information Only by By setting, selecting or adjusting the equalizer device from the above, you can easily set frequency A, frequency B, and frequency C. It is possible to flatten and improve the frequency-to-sound pressure characteristics in the bass range of the speaker system.

[0120] The diameter of the speaker unit for these frequencies A, B, and C depends on the setting, choice, Or the adjustment operation is, By using collective or individual switching SW or component plug-ins In exchange It can be adjusted continuously with aperture and symbol. Operation means It is also possible. Equalizer deviceNo switching at all, exchange or adjustment Means of operation The equalizer device itself can be selected so that the diameter of the speaker unit and the equalizer device correspond one-to-one. It is also possible .

[0121] In this case, even if the equalizer device is fixed and has no means of adjustment, as described above, it is possible to improve the flattening of the frequency vs. sound pressure characteristics in the low frequency range. If there is an adjustment range, this will be a representative value. position (median value) It is also possible to provide a means of adjustment that clearly defines the adjustment. The median value Select the speaker size at the position. Then measure By adjusting the adjustment means, it is possible to more precisely flatten and improve the frequency vs. sound pressure characteristics. In addition, the adjuster can adjust the sound to suit his or her own preference based on the sound he or she hears.

[0122] The adjustment means is very valuable at frequency A. This is because in Patent Document 1, there is a range of appropriate magnifications of frequency A to fo depending on the diameter of the speaker unit used, fo, the frequency of the bass reflex resonance, and the peak of the sound pressure. In Patent Document 1, frequency A is set to 0.5 of fo. Double to Although it is stated as twice the value, the present patent does not limit the scope to that of Patent Document 1, nor does it fix the central value (reference value) at 1 time fo.

[0123] The attenuation of the BEF circuit at frequency C can be fixed at a constant value if the speaker system to be used is restricted to a certain extent. For example, according to Patent Document 1, By acoustic resistance If use is limited to speaker systems that suppress mechanical resonance, it can be fixed as (B") between (A") and (C") in Figure 7, or (B") can be fixed closer to (A") or (C") depending on the expected degree of suppression of mechanical resonance. Also, if use is limited to conventional general bass reflex speaker systems, it can be fixed at (C") in Figure 7.

[0124] However, if the speaker system to be used is not restricted, the attenuation of the BEF circuit can be adjusted. In this case, the adjustment amount is set to approximately the midpoint between (a") and (c") as shown in Figure 7 (b"). Set it as the center value ,(stomach") ~ (c") range. Median value and The adjustment range is not limited. [Industrial Applicability]

[0125] The present invention provides an equalizer device for use in industries that provide audio equipment, when a speaker system is made by oneself, or when only the speaker system of the audio equipment shown in Patent Document 1 is commercialized. [Explanation of symbols]

[0126] 1,1',1”···Speaker unit 101....Speaker unit 1 diaphragm 2,2',2” Box 201,201',201”...Inner space of box 2 202 Bass reflex duct 3...Acoustic resistance material 301: Surface of the acoustic resistance material 3 located in the inner space 201 4. Partition wall 5. Sound source (signal generation) device 6. Equalizer device of the present invention 601 Signal level adjustment 602 Amplification circuit 603···Equalizer (CR filter) circuit 604... Buffer amplifier 605···BEF circuit

Claims

1. An acoustic equalizer device which controls the frequency-to-sound pressure characteristics of a speaker unit in the low-frequency range, wherein at frequencies A and B where A<B, the gain at frequency A is greater than the gain at frequencies B or higher, and wherein the gain between frequencies A and B changes at 6 dB / oct, and the frequency-to-gain characteristics of a BEF (band elimination filter) are centered on frequency C where C<B, and wherein the device is equipped with means for uniquely setting, selecting or adjusting frequencies A, B and C based on the aperture of the speaker unit in question.

2. 2. The acoustic equalizer device according to claim 1, further comprising a means for adjusting a gain at frequency C of the BEF centered on said frequency C.

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