JP2006013571A - Speaker unit and speaker system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speaker unit capable of extending a reproduction band at low-frequency sound without using an auxiliary speaker unit, and to provide a speaker system. <P>SOLUTION: Two magnetic gaps X, Y with large and small diameters are concentrically arranged, a diaphragm 17 is fixed to a first voice coil bobbin 16 located in the magnetic gap X with a small diameter to obtain a first vibration system, a second voice coil bobbin 20 located in the magnetic gap Y of a large diameter is fixed to a damper or a coupler whose outer circumferential part is fixed to a frame to obtain a second vibration system, a lower part of the second voice coil bobbin is fixed to the damper 22, the first and second voice coil bobbins 16, 20 are mutually coupled by a coupling member 23 so as to match the mechanical impedance between the first and second vibration systems or to make vertical moving speeds of the first and second voice coil bobbins substantially identical to each other thereby suppressing the increase in the minimum resonance frequency and the resonance sharpness and extending the low-frequency sound band. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a speaker unit used for various types of audio equipment and a speaker system using the unit, and more specifically, a speaker unit capable of expanding a bass reproduction band with one speaker. And a speaker system using this speaker unit.

  In the conventional speaker system, the sealed method, which is one of the bass reproduction methods, is the lowest resonance frequency of the speaker system because the air pressure applied to the back of the speaker diaphragm is equivalently applied as a stiffness acting as an air spring. However, it is considerably higher than the lowest resonance frequency of the speaker unit itself used, and it is difficult to expand the reproduction band with low sound.

  Therefore, as one of the measures for suppressing the increase in the lowest resonance frequency of the speaker system and expanding the bass reproduction band, for example, in Japanese Patent Laid-Open No. 8-79886 (Patent Document 1), it corresponds to the spring of the speaker unit. There is disclosed a speaker without a damper (so-called damperless speaker) that reduces the stiffness, suppresses the rise in the lowest resonance frequency, and expands the bass reproduction band by deleting the damper.

  In addition, in the “new edition speaker & enclosure Encyclopedia” (Non-patent Document 1) and the like, the first speaker used for radiating sound to the outside and the partition plate provided inside the cabinet are connected to the first speaker. A so-called double drive type speaker system is disclosed in which a second speaker is provided to control the movement of the sound to increase the bass reproduction band.

This double drive type speaker system will be described more specifically. For example, as shown in FIG. 9, the double drive type speaker system is used to radiate sound to the air chamber A part formed in the cabinet D of the speaker system 1. The first speaker 2 for front emission is provided, and the air chamber B formed by the partition plate 3 on the back side of the first speaker 2 is affected by the pressure of air applied to the back side of the diaphragm of the first speaker. A second speaker 4 is provided so as to be excluded.
That is, the second speaker 4 is controlled so that the pressure of the air that prevents the movement of the first speaker 2 is substantially zero, and the first speaker 2 is apparently provided on an infinite baffle. In this way, the reproduction band can be expanded with a low sound.

In the double drive speaker system shown in FIG.
1) The first speaker for front emission provided in the air chamber A is V1,
2) It is set to V2 with the 2nd speaker for auxiliary provided in air chamber B,
further,
3) The vibration area ratio of the first speaker and the second speaker is n (where n = Sq2 / Sq1).
When the volume velocity of both is equal so that the air pressure applied to the back of the diaphragm of the first speaker becomes zero,
V1 = nV2
Therefore, the relationship between the impedances Z1 and Z2 of both mechanical systems is
Z2 = n (F2 / F1) * Z1
It can be asked.

  Under this condition, the impedance Z3 indicating the stiffness equivalent to the pressure of the air applied to the back surface of the diaphragm of the first speaker in the mechanical simple equivalent circuit is eliminated in the above formula. Since Z3 becomes irrelevant to the circuit, and the circuit can be regarded as equivalent to a series circuit from which Z3 is removed, it becomes equivalent to a general sealed cabinet. (See Figure 10)

Therefore, the above condition “Z2 = n (F2 / F1) * Z1”
By setting and using two speakers so as to meet the requirements, a speaker system is constructed in which the speaker on the side that emits sound is not affected by the stiffness of the back of the diaphragm, and the minimum resonance frequency increases. The low frequency band has been expanded.
Japanese Patent Laid-Open No. 8-79886 (FIG. 1, paragraph number 0033) Supervised by Tamon Saeki “New Edition Speaker & Enclosure Encyclopedia” (Seibundo Shinkosha) published in 1999 p. 118 and p. 105

  The damperless speaker described in Patent Document 1 realizes the expansion of the bass reproduction band by deleting the damper to suppress the rise of the lowest resonance frequency in order to reduce the influence of the stiffness. However, since the damper for accurately holding the voice coil in the gap is deleted, the voice coil is not accurately held in the gap, and the voice coil rolls (rolling phenomenon) during vibration, The voice coil bobbin and the voice coil are in contact with the components of the magnetic circuit and have the disadvantage that they are liable to cause defects such as generation of abnormal noise and disconnection of the voice coil.

  Further, in order to prevent rolling of the voice coil, there is a measure to make the edge hard, but it has a drawback that the minimum resonance frequency and the sharpness of resonance increase. Further, there is a method of preventing the voice coil bobbin or the voice coil wire from coming into contact with the components of the magnetic circuit by widening the gap of the magnetic circuit. However, there is a drawback that the magnetic flux density is lowered by widening the gap, and the sound pressure cannot be reduced. Furthermore, a resin film is formed on the side surface of the pole, and the dimensional relationship between the inner diameter of the plate, the outer shape of the pole, the inner diameter of the voice coil and the outer diameter of the voice coil is regulated, and the magnetic gap is filled with a magnetic fluid. However, there is a problem to be solved in manufacturing the speaker.

  On the other hand, as can be seen from FIG. 9, the double drive speaker system described in Non-Patent Document 1 includes a front-radiation speaker unit (first speaker) and an auxiliary speaker unit (second speaker) for enhancing bass. The two speaker units are indispensable systems, and the air chambers of the respective speaker units are required, so that the structure becomes complicated, and the price is reduced or the size and / or thickness is reduced. It is difficult to plan.

  As an operating condition of the double drive type speaker system, it is necessary to make the volume velocity of the speaker for front radiation, which is the first speaker unit, the same as the volume velocity of the auxiliary speaker, which is the second speaker unit. . However, the speaker unit has various unstable elements such as dimensional accuracy of components, variations in initial physical properties of materials, changes with time of physical properties due to fatigue during vibration, and nonlinearity of vibration. Therefore, the change in mechanical impedance cannot be ignored, and it is extremely difficult to make the volume velocity the same by matching the mechanical impedances of the first speaker and the second speaker. The current situation is difficult to obtain.

  As a method for solving the above-described drawbacks, as disclosed in Non-Patent Document 1, the current flows through the voice coil of the first speaker in an MFB (motional feedback) system in which the second speaker on the back side is used for control. As a structure for detecting the velocity component from the current and driving the second speaker via the control circuit, there is a technology in which the two speakers operate at the same phase and the same volume velocity. A special electric circuit such as a control circuit is required, and it is difficult to reduce the cost.

In view of the present situation, the present invention provides a single speaker unit without using an auxiliary speaker unit, and without using a plurality of air chambers or a new electric circuit in a cabinet, while using a damper. An object of the present invention is to provide a speaker unit and a speaker system capable of expanding a reproduction band with low sound.

In order to achieve the above object, the invention according to claim 1 of the present invention provides:
Two magnetic gaps with different diameters are arranged concentrically,
The upper part of the first voice coil bobbin disposed in the small-diameter magnetic gap is fixed to the center part of the diaphragm whose outer peripheral part is fixed to the frame via the edge to form the first vibration system,
The upper part of the second voice coil bobbin disposed in the large-diameter magnetic gap is fixed to the inner peripheral part of a damper or coupler whose outer peripheral part is fixed to the frame to form a second vibration system.
The lower part of the second voice coil bobbin is fixed to the inner peripheral part of a damper whose outer peripheral part is fixed to the frame, and the first and second voice coil bobbins are connected to each other by a connecting material. so,
By matching the mechanical impedances of the first vibration system and the second vibration system, or by making the vertical movement speeds of the first and second voice coil bobbins substantially the same,
The speaker unit is configured to suppress an increase in the minimum resonance frequency and the sharpness of resonance and to expand a bass band.

The invention according to claim 2 of the present invention is
The speaker unit according to claim 1,
The small-diameter magnetic gap is
A first magnetic circuit formed of a cylindrical center pole provided on the upper surface of the bottom yoke having a required diameter, a columnar magnet disposed in the center pole, and a pole piece disposed on the magnet. The pole piece is formed between the outer periphery of the pole piece and the inner periphery of the center pole.

The invention according to claim 3 of the present invention is
The speaker unit according to claim 1,
The large-diameter magnetic gap is
A cylindrical center pole provided on the top surface of the bottom yoke having a required diameter, a ring-shaped magnet disposed on the bottom yoke on the outer periphery of the center pole, and a top plate disposed on the magnet. The second magnetic circuit is formed between the inner periphery of the top plate and the outer periphery of the center pole.

The invention according to claim 4 of the present invention is
The speaker unit according to claim 1,
The connecting material is
The first voice coil bobbin and the second voice coil bobbin are one flexible damper that holds the first voice coil bobbin and the second voice coil bobbin in common.

The invention according to claim 5 of the present invention is
The speaker unit according to claim 1,
The connecting material is
It is made of a material having rigidity.

Furthermore, the invention according to claim 6 of the present invention is
The speaker unit according to any one of claims 1 to 5,
It is a speaker system characterized by being attached to a closed cabinet.

  In the speaker unit according to the present invention, two magnetic gaps having different diameters are concentrically arranged, and the first vibration system is disposed in the small-diameter magnetic gap, and the second vibration system is disposed in the large-diameter magnetic gap. Since each of the first voice coil bobbins constituting the first vibration system and the second voice coil bobbins constituting the second vibration system are connected to each other by a connecting material, the first vibration is arranged. By matching the mechanical impedance of the system and the second vibration system, or by making the first and second voice coil bobbins move substantially the same speed, the lowest resonance frequency and the sharpness of resonance The bass band can be expanded by suppressing the rise of the sound.

In the speaker system according to the present invention, the bass band can be expanded by suppressing the increase of the minimum resonance frequency and the sharpness of resonance by a very simple and easy means of mounting one speaker unit having the above-described configuration on the cabinet. In addition, the system structure is simple, the size can be reduced, and the product cost can be reduced.

  1 is a cross-sectional view showing an example of a speaker unit according to the present invention. FIG. 2 is a circuit diagram showing a mechanical equivalent circuit of FIG. 3 is a schematic explanatory view showing an example of a speaker system using the speaker unit according to the present invention, FIG. 4 is a circuit diagram showing a mechanical equivalent circuit of the speaker system shown in FIG. 3, and FIG. 5 is a speaker unit according to the present invention. FIG. 6 is a circuit diagram showing the mechanical equivalent circuit of FIG. 5, FIG. 7 is an explanatory diagram of a conventional damperless speaker system, and FIG. 8 shows the mechanical equivalent circuit of FIG. It is a circuit diagram. 9 is a schematic explanatory diagram of a double drive type speaker system, and FIG. 10 shows a mechanical equivalent circuit of FIG.

In the speaker unit according to the present invention, two magnetic gaps having different diameters are arranged concentrically, and a first voice coil bobbin joined to a diaphragm is arranged in one small-diameter magnetic gap to provide a first vibration system. The second voice coil bobbin that is not joined to the diaphragm is arranged in the other large-diameter magnetic gap to form a second vibration system, and the voice coil bobbins are interconnected by a connecting material. Thus, various modifications can be made within the scope not changing this gist, and the present invention is not limited only to the embodiments described later.

  The speaker unit 10 shown in FIG. 1 has two magnetic gaps X and Y having different diameters concentrically on a bottom yoke 12 having a required diameter provided with a cylindrical center pole 11 having a required diameter at the center of the upper surface. Specifically, the first magnet of the inner magnet type is composed of a columnar magnet 13 fixed on the bottom portion of the bottom yoke 12 and a pole piece 14 fixed on the magnet 13. In this first magnetic circuit, a gap formed between the outer periphery of the pole piece 14 and the inner periphery of the cylindrical pole piece 11 is defined as a magnetic gap X.

  In addition, the magnetic gap Y secures a ring-shaped magnet 14 on the bottom yoke 12, and a ring-shaped top plate 15 is secured to the upper portion thereof to constitute an outer magnet type second magnetic circuit. This second magnetic circuit is formed between the outer periphery of the center pole 11 and the inner periphery of the top plate 15.

  A first voice coil bobbin 16 equipped with a voice coil x is disposed in the magnetic gap X having a small diameter, and the central portion of the diaphragm 17 is fixed to the upper outer peripheral portion to constitute the first vibration system. Thus, the outer peripheral portion of the diaphragm 17 is fixed to the outer periphery of the opening portion of the frame 19 fixed to the top plate 15 via the edge 18.

  Further, a second voice coil bobbin 20 equipped with a voice coil y is disposed in the magnetic gap Y having a large diameter, and a lower outer peripheral portion is fixed to the frame 19 by a damper 21 whose upper outer peripheral portion is fixed to the frame 19. The first vibration coil bobbin 16 and the second voice coil bobbin 20 are connected to each other by a connecting member 23, which is held by a damper 22 to constitute a second vibration system.

  As is apparent from FIG. 1, the connecting member 23 serves to accurately hold the first voice coil bobbin 16 in the magnetic gap X of the first magnetic circuit, and the lower part of the second voice coil bobbin 20. The damper 22 is substantially the same as the damper 22 that supports the outer peripheral portion, and is made of a low-density, lightweight material such as cotton or chemical fiber. It should be noted that the damper 22 may be integrally formed or may be formed of the same material.

  In FIG. 1, 24 is a dust cap, 25 is a gasket, 26 is a lead wire for connecting the first voice coil x and the input terminal 27, and 28 is a lead for connecting the second voice coil y and the input terminal 29. In this configuration, electric inputs are applied in parallel to the input terminals 27 and 29.

Hereinafter, the operation of the speaker unit 10 having the above-described configuration will be described using a mechanical equivalent circuit.
The mechanical equivalent circuit of the speaker unit 10 is as shown in FIG. 2 and includes a first voice coil x, a first voice coil bobbin 16, a diaphragm 17, an edge 18, a dust cap 24, and a lead wire 26. A first vibration system (hereinafter referred to as vibration system 1), a second voice coil y, a second voice coil bobbin 20, dampers 21 and 22, and a second vibration system (hereinafter referred to as lead wire 28). The reactance is inserted between the vibration system 1 and the vibration system 2 in parallel by the stiffness S3 ′ provided by the connecting member 23 that mechanically couples the vibration system 2).

  FIG. 4 shows a mechanical equivalent circuit of the speaker system when the speaker unit 10 is attached to a sealed cabinet C as shown in FIG. When the speaker unit 10 is placed in a closed cabinet C, the reactance due to the stiffness Sb ′ determined from the volume of air inside the cabinet C and the effective vibration area of the vibration system 1 is in series with the mechanical impedance of the vibration system 1. It becomes a form to be newly inserted.

  The reason is that the stiffness of the edge 18 of the vibration system 1 is increased because the pressure due to the elasticity of the air inside the cabinet C is applied to the vibration surfaces of the edge 18, the vibration plate 17, and the dust cap 24 of the vibration system 1. It is for showing the same effect | action. Further, since the dampers 21 and 22 of the vibration system 2 have air permeability, the effective vibration area can be ignored, so that they are not affected by the stiffness Sb '. That is, in the mechanical equivalent circuit, there is no stiffness Sb ′ in the closed circuit of the vibration system 2.

So, like the conventional double drive speaker system,
The vibration speed of the vibration system 1 is V1 ′, and the vibration speed V2 ′ of the vibration system 2 is
V1 '= V2'
When the condition to be
Z2 ′ = (F2 ′ / F1 ′) * Z1 ′
Thus, the expression does not include Z3.
In order for this equation to hold for all numerical values, this equation should be made the identity for ω (angular frequency) and the coefficients should be equal for the same order on both sides.

  Therefore, the relational expressions for the equivalent resistance, equivalent stiffness, and equivalent mass are obtained as follows.

In the above formula, each symbol has the following meaning.
R1 ′; equivalent resistance of vibration system 1 R2 ′; equivalent resistance of vibration system 2 M1 ′; equivalent mass of vibration system 1 M2 ′; equivalent mass of vibration system 2 S1 ′ (= Se ′); equivalent stiffness of vibration system 1 S2 ′ (= Sb ′); Equivalent stiffness of vibration system 2 S1 ″; Sum of stiffness of edge and internal volume of cabinet

  Under the condition that the above relational expression is satisfied, the stiffness S3 ′ is irrelevant to the circuit. Therefore, the circuit can be regarded as a series circuit with the stiffness S3 ′ removed, and the mechanical equivalent circuit of the sealed speaker system can be regarded as a circuit. Become equivalent.

Next, a comparison of the lowest resonance frequency between the conventional damperless speaker system and the speaker system of the present invention (Example 1) is as follows.
In the case of a sealed speaker system with a conventional damperless speaker (see Fig. 8)

Where F ₀ : Minimum resonance frequency
Se; Edge stiffness
Sb: Stiffness of the internal volume of the cabinet
M: Equivalent mass

  In the case of a sealed speaker system equipped with the speaker of Example 1 (see FIG. 4)

Where F ₀ '; lowest resonance frequency
S1 "; Sum of stiffness of edge and cabinet internal volume
S2 ': Sum of two damper stiffnesses of vibration system 2
M1 ′: Equivalent mass of vibration system 1
M2 ′: Equivalent mass of vibration system 2

  Therefore, by substituting (2), (3) into (5) and erasing S1 ″, S2 ′, M2 ′, equation (4) can be modified as follows.

Furthermore, the resonance sharpness of the conventional damperless speaker system and the speaker system of the present invention (Example 1) are compared as follows.
In the case of a sealed speaker system with a conventional damperless speaker (see Fig. 8)

Qo: Sharpness of resonance
Se: Edge stiffness
Sb: Stiffness of the internal volume of the cabinet
M: Equivalent mass
R: equivalent resistance

  In the case of a sealed speaker system equipped with the speaker of Example 1 (see FIG. 4)

However, Qo ': Sharpness of resonance
S1 "; Sum of stiffness of edge and cabinet internal volume
S2 ': Sum of two damper stiffnesses of vibration system 2
M1 ′: Equivalent mass of vibration system 1
M2 ′: Equivalent mass of vibration system 2
R1 ′: Equivalent resistance of vibration system 1
R2 ': Equivalent resistance of vibration system 2

  Therefore, by substituting (1), (2), (3) into (8) and deleting R2 ', S1 ", S2', M2 ', equation (8) can be transformed as follows.

Therefore, under the condition where the vibration speeds of the vibration system 1 and the vibration system 2 are equal, the expression (6) has the same form as the expression (4). Also, equation (9) has the same form as equation (7). Here, since there is no damper stiffness in the equations (6) and (9), it can be derived that the lowest resonance frequency and the sharpness of resonance do not (apparently) depend on the damper stiffness. Therefore, it can be said that Example 1 has the same operation as when a damperless speaker is mounted and driven in a closed cabinet, so that the stiffness is reduced as compared with a speaker system using a general damper. Thus, it is possible to suppress the increase of the minimum resonance frequency and the sharpness of resonance and to expand the bass band.

  The speaker unit 30 shown in FIG. 5 shows another embodiment of the speaker unit according to the present invention, and basically has the same configuration as that of the above-described embodiment 1. Therefore, the same parts are denoted by the same reference numerals. Only the differences will be described.

  That is, in the speaker unit 30, the upper outer peripheral portion of the second voice coil bobbin 20 constituting the second vibration system is connected to the coupler 31 whose other end is fixed to the frame 19 via the edge 18, The connecting member 23 that connects the first voice coil bobbin 16 and the second voice coil bobbin 20 to each other is made of a material having rigidity such as hard plastic or metal, and the first vibration system and the second vibration system. The vibration speed is forcibly made the same.

  In this way, by replacing the material of the connecting material 23 with a rigid body such as hard plastic or aluminum, the first vibration system and the second vibration system vibrate together, and the first vibration system and Since the condition that the vibration speeds of the second vibration system are the same can be obtained, as in the case of the first embodiment, an effect of suppressing the increase in the minimum resonance frequency and the sharpness of resonance and expanding the low frequency band can be obtained. .

  Considering the simple equivalent circuit of the mechanical system in this case, the first vibration system and the second vibration system move as a rigid body at the same speed, so that they are irrelevant to the stiffness S3 ′ and the reactances in parallel are released from the circuit. As can be seen from the mechanical simple equivalent circuit shown in FIG. 6, the series circuit is the same as that of a general speaker.

  And in the low frequency band, the total equivalent resistance, total equivalent mass, and total equivalent stiffness in the circuit can be regarded as lumped constants of one element each, so the vibration form is a substantially simple one-degree-of-freedom forced vibration Therefore, the low-frequency sound pressure characteristics near the lowest resonance frequency can be easily obtained with less inflection points and less unevenness.

  In addition, since the first vibration system and the second vibration system are structurally connected by the rigid connecting member 23, the total equivalent resistance, the total equivalent mass, the total vibration total of the vibration system 1 and the vibration system 2 are all included. It can be considered that the equivalent stiffness and the total driving force are distributed to the vibration system 1 ′ and the vibration system 2 ′ in an apparent ratio, that is, an imaginary ratio. In other words, by matching the mechanical impedances of the apparent vibration system 1 ′ and the vibration system 2 ′, it can be said that the respective vibration speeds are the same.

  Therefore, unlike the conventional double drive speaker, the mechanical impedances of the apparent vibration system 1 ′ and the vibration system 2 ′ are not subject to the restriction of matching the mechanical impedance of the vibration system 1 and the mechanical impedance of the vibration system 2. Are easily matched and the vibration speeds of the vibration system 1 and the vibration system 2 can be made equal.

That is, in the case of a speaker system having a high equivalent stiffness S1 ″ value, which is the sum of the stiffness of the edge of the vibration system 1 and the internal volume of the cabinet, for example, a small speaker system, For example, under the condition of F1 ′ = F2 ′, the damper equivalent stiffness S2 ′ of the vibration system 2 is equal to the S1 ″ value of the vibration system 1 in order to match the mechanical impedance of 1 and the vibration system 2. It is necessary to increase the value.
However, in the second embodiment, there is no restriction that the equivalent stiffness S2 ′ of the vibration system 2 is set to the same value as the equivalent stiffness S1 ″ of the vibration system 1, so that the equivalent stiffness S2 ′ can be freely set regardless of the value of the equivalent stiffness S1 ″. Therefore, if the S2 ′ value is set low, it is possible to suppress the increase in the minimum resonance frequency and the sharpness of resonance and to expand the bass band.

It is sectional drawing which shows an example of the speaker unit concerning this invention. FIG. 2 is a circuit diagram showing a mechanical equivalent circuit of FIG. It is a schematic explanatory drawing which shows an example of the speaker system using the speaker unit concerning this invention. FIG. 4 is a circuit diagram showing a mechanical equivalent circuit of the speaker system shown in FIG. 3. It is sectional drawing which shows the other example of the speaker unit concerning this invention. It is a circuit diagram which shows the mechanical equivalent circuit of FIG. It is explanatory drawing of the conventional damperless speaker system. It is a circuit diagram which shows the mechanical system equivalent circuit of FIG. It is a schematic explanatory drawing of the conventional speaker system of a double drive system. 10 shows the mechanical equivalent circuit of FIG. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Speaker unit 11 Cylindrical center pole 12 Bottom yoke 13 Columnar magnet 14 Ring-shaped magnet 15 Top plate 16 1st voice coil bobbin 17 Diaphragm 18 Edge 19 Frame 20 2nd voice coil bobbin 21, 22 Damper 23 Connection Material X Small-diameter magnetic gap Y Large-diameter magnetic gap x, y Voice coil

Claims (6)

Two magnetic gaps with different diameters are arranged concentrically,
The upper part of the first voice coil bobbin disposed in the small-diameter magnetic gap is fixed to the center part of the diaphragm whose outer peripheral part is fixed to the frame via the edge to form the first vibration system,
The second vibration system is formed by fixing the inner periphery of a damper or coupler whose outer periphery is fixed to the frame on the upper part of the second voice coil bobbin disposed in the large-diameter magnetic gap,
The lower part of the second voice coil bobbin is fixed to the inner peripheral part of a damper whose outer peripheral part is fixed to the frame, and the first and second voice coil bobbins are connected to each other by a connecting material. so,
By matching the mechanical impedances of the first vibration system and the second vibration system, or by making the vertical movement speeds of the first and second voice coil bobbins substantially the same,
A loudspeaker unit configured to suppress an increase in minimum resonance frequency and sharpness of resonance and to expand a bass band. The small-diameter magnetic gap is
A first magnetic circuit formed by a cylindrical center pole provided on the upper surface of the bottom yoke having a required diameter, a columnar magnet disposed in the center pole, and a pole piece disposed on the magnet. The speaker unit according to claim 1, wherein the speaker unit is formed between an outer periphery of the pole piece and an inner periphery of the center pole. The large-diameter magnetic gap is
A cylindrical center pole provided on the top surface of the bottom yoke having a required diameter, a ring-shaped magnet disposed on the bottom yoke on the outer periphery of the center pole, and a top plate disposed on the magnet. The speaker unit according to claim 1, wherein the second magnetic circuit is formed between an inner periphery of the top plate and an outer periphery of the center pole. The connecting material is
The speaker unit according to claim 1, wherein the speaker unit is a flexible damper that holds the first voice coil bobbin and the second voice coil bobbin in common. The connecting material is
The speaker unit according to claim 1, wherein the speaker unit is made of a material having rigidity. The speaker unit according to any one of claims 1 to 5,
A speaker system characterized by being mounted in a closed cabinet.