JPH05122786A - Speaker system - Google Patents

Abstract

PURPOSE:To enhance the low-pass sensitivity in a small-capacity cabinet. CONSTITUTION:The effective inner content volume of the cabinet 1 is enlarged because a folding duct 8A is drawn from the external back surface to the external front side of a cabinet 1. Thus minimizing the loss in the folding duct 8A, resulting in enhancing the low-pass sensitivity in a small-capacity cabinet. Thus, the low-pass sensitivity of a small capacity of cabinet can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bass reflex type speaker system.

[0002]

Bass reproduction in a speaker system is dominated by the cabinet. Cabinets come in a variety of formats, each playing a sound with its own characteristics. The cabinet that considers such sound reproduction is
There are a closed type in which the back surface of the speaker is completely sealed for the purpose of blocking sound waves from the back surface of the speaker, and a bass reflex shape in which the sound wave emitted from the back surface of the speaker is positively used.

The bass reflex type cabinet is provided with a bass reflex duct, and a part of the sound radiated from the rear surface of the speaker is radiated through this port in phase with the sound from the front surface of the speaker to provide a bass characteristic. It is designed to augment. FIG. 13 shows an example of such a bass reflex type cabinet, and a speaker unit 2 is attached to the upper front portion of the cabinet 1. A bass reflex duct 3 of a predetermined length is arranged below the speaker unit 2. A sound absorbing material 4 is laid on the inner surface of the cabinet 1. Then, a part of the sound radiated from the rear surface of the speaker unit 2 is radiated through the port 3a of the bass reflex duct 3 in phase with the sound from the front surface of the speaker unit 2, thereby enhancing the bass characteristic.

FIG. 12 shows an example of another bass reflex type cabinet provided with a folding duct, and a folding duct 8 is arranged below the speaker unit 2 of the cabinet 1. The folding duct 8 is provided with a horizontal duct portion 9 and a vertical duct portion 10. The tip of the horizontal duct portion 9 of the folding duct 8 is the cabinet 1.
Installed on. Thereby, the sound wave from the opening of the vertical duct portion 10 is emitted to the outside of the cabinet 1 through the vertical duct portion 10 and the horizontal duct portion 9.

In addition, in order to increase the low-frequency sensitivity, the cabinet volume, port length, unit, etc. are adjusted to change fob, and fob is kept constant to increase port and duct dimensions (cross-sectional area and length). There is a method of reducing the port resistance. The former method is shown by the characteristic diagram of FIG. 14, and the latter method is shown by FIG.
5 is shown by the characteristic diagram.

[0006]

By the way, in each of the above-mentioned speaker systems, when adjusting the sensitivity in the low frequency range, the air in each of the ports 3a, 9a is increased by increasing the opening area of each of the ports 3a, 9a. The resistance can be reduced, and the low range sensitivity can be increased by the amount that the loss is reduced.

However, in the small speaker system, the ports 3a and 9a are provided to increase the low-range sensitivity without changing the resonance frequencies of the ducts 3 and 8.
If the opening area of is increased, the volumes of the ducts 3 and 8 will be increased at the same time, and the effective internal volume of the cabinet will be decreased accordingly. for that reason,
In the conventional small bass reflex type speaker system, there is a problem that the effect of increasing the opening area of each port 3a, 9a to reduce the loss of the port does not directly increase the low-frequency sensitivity. ..

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a speaker system capable of increasing the low frequency sensitivity in a small capacity cabinet.

[0009]

SUMMARY OF THE INVENTION The present invention provides a speaker system for radiating a part of sound emitted from the back surface of a speaker provided inside a cabinet to the outside of the cabinet via the bass reflex duct. Is drawn out from the outer back side or side surface of the cabinet to the outer front side.

Further, according to the present invention, in the speaker system in which a part of the sound radiated from the back surface of the speaker is radiated to the outside of the cabinet through the bass reflex duct provided inside the cabinet, the volume of the bass reflex duct is set to Vp. When the volume of the cabinet is Vc and the resonance frequency of the bass reflex duct is constant, the dimensions of the bass reflex duct are determined according to the following condition: Vc * 0.05 <Vp <Vc * 0.15. It is characterized by

[0011]

In the speaker system of the present invention, since the bass reflex duct is provided so as to be pulled out from the outer back side or side of the cabinet to the outer front side, the effective internal volume of the cabinet can be increased, so that the inside of the bass reflex duct can be increased. Since the loss can be reduced, it is particularly effective in increasing the low frequency sensitivity in a small capacity cabinet.

Further, in the speaker system of the present invention, when the volume of the bass reflex duct is Vp, the volume of the cabinet is Vc, and the resonance frequency of the bass reflex duct is constant, the dimension of the bass reflex duct is Vc × 0.05. It was determined according to the condition of <Vp <Vc x 0.15. That is, it was found that there is a size of the bass reflex duct capable of maximizing the low frequency sensitivity between the size where the loss of the bass reflex duct affects the sensitivity and the size where the reduction of the cabinet volume affects the sensitivity.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, parts common to those in FIG. 12 will be assigned the same reference numerals and overlapping description will be omitted. FIG. 1 shows an embodiment of a speaker system of the present invention, in which a bending duct 8A is drawn out from the outer rear side of a cabinet 1 having a speaker unit 2 to the outer front side. The bent duct 8A is provided with a vertical duct portion 10A and a horizontal duct portion 9A.

The port 9b of the bent duct 8A communicates with the inside of the cabinet 1, and the port 9a is flush with the front surface of the cabinet 1. Then, the sound wave radiated from the back surface of the speaker unit 2 is transmitted from the port 9b to the vertical duct portion 10A, further transmitted to the horizontal duct portion 9A, and is emitted to the outside from the port 9a. Next, the operation of the bending duct 8A externally attached to the cabinet 1 will be described.

First, consideration will be given to the friction loss of a normal pipeline. For example, as shown in FIG. 2, when the friction loss pressure between p1 and p2 is h, the loss pressure is h = λ · (l / d) · (v ² / 2g) = λ · (l / d) (Ρv ² / 2g) (1) where l is the distance (m) between p1 and p2, d is the diameter of the conduit (m), v is the velocity of the fluid (m / s), and g is Gravity acceleration (m / s ² : 9.8), ρ is fluid density (kg / m ³ : air 1.204), λ is pipe friction coefficient (according to the following).
Are shown respectively.

Considering the pipe friction coefficient λ, In the case of laminar flow inside a smooth tube (Re <300
0), λ = 64 / Re. In the case of turbulent flow inside a smooth tube (3000 <Re <
300000), λ = 0.3164 / Re 1/4. In case of turbulent flow on rough surface (3000 <Re <30
0000)

[0017]

[Equation 1] By the way, ε = 0.00018 (m) in the case of a wood pipe. Re: Reynolds number = inertial force / viscous force = [(mass) ×
(Acceleration)] / [(shear stress) × (area)] = v · d /
ν (ν = μ / ρ) ν: Kinetic viscosity coefficient (m ² / s) μ = Viscosity coefficient

Generally, the total line loss hT is given by the following equation.

[Equation 2] By the way,

[Equation 3] Is a value determined by the shape of the port (refractive tube, curved tube, etc.), and becomes larger as the number of bending times increases.

The total loss Fpl in the duct is calculated by the following equation.

[Equation 4]

The resistance Rp in the duct is

[Equation 5] Rpp = Rp (Sd / Sp) ² (5) where Rpp is a converted value that enters the equivalent circuit of the speaker.
If the dimensions (diameter and length) of the duct are changed and the loss is calculated under the conditions shown in the above (1) to (5) and FIG. 3, the results of FIGS. 4 and 5 to 8 are obtained.

By the way, FIGS. 5 to 8 show the case where the volume of the cabinet 1 is constant at 1.2 l, and the bending duct 8
This is the case where A is externally attached to the cabinet 1. Here, FIG. 10 shows the result of obtaining Rpp based on the conditions A to D shown in FIG. 9 and substituting it into the equivalent circuit of the speaker to obtain the sound pressure from the port 9a. As can be seen from the figure, comparing A and C when the bending duct 8A is externally attached to the cabinet 1, C having a small internal resistance shows a high sound pressure.

It can also be seen that A and C show much higher sound pressure than B and D when the folding duct is provided inside the cabinet 1. In the figure, a large resistance means that the port is bent many times, and a small resistance means that the port is bent few times. As described above, in this embodiment, since the folding duct 8A is provided so as to be pulled out from the outer rear side of the cabinet 1 to the outer front side, the effective internal volume of the cabinet 1 can be increased, and therefore the folding duct. It is possible to reduce the loss in 8 A, which is particularly effective in increasing the low frequency sensitivity in a small capacity cabinet.

FIG. 11 shows another embodiment in which the bending duct is provided inside the cabinet 1. Below the speaker unit 2, a bending duct 8 is arranged. The folding duct 8 is provided with a horizontal duct portion 9 and a vertical duct portion 10. The port 9a of the horizontal duct portion 9 of the folding duct 8 is open to the outside. The bending duct 8 in the speaker system having such a configuration is determined according to the following conditions.

That is, when the duct resonance frequency is fixed and the opening area of the port 9a is increased, the bending duct 8 is
There is a condition for maximizing the low-pass sensitivity between the size where the loss of 1 affects the low-pass sensitivity and the size where the decrease in the volume of the cabinet 1 affects the low-pass sensitivity. Here, when the volume of the bending duct 8 is VP and the volume of the cabinet 1 is VC, the low frequency sensitivity is maximized when the condition of VC × 0.05 <VP <VC × 0.15 is satisfied. .. As described above, in this embodiment, since the duct resonance frequency is fixed and the size of the bent duct 8 is determined so as to satisfy the condition of VC × 0.05 <VP <VC × 0.15, the low-range sensitivity is improved. Can be increased.

[0025]

As described above, according to the speaker system of the present invention, the loss in the bass reflex duct is reduced by increasing the effective internal volume of the cabinet. It is effective in increasing the range sensitivity. Further, the dimensions of the bass reflex duct when the volume of the bass reflex duct is Vp, the volume of the cabinet is Vc, and the resonance frequency of the bass reflex duct is constant, the condition is Vc × 0.05 <Vp <Vc × 0.15. The bass reflex duct is dimensioned so that the low-frequency sensitivity is maximized. As a result, it is possible to increase the low frequency sensitivity in a small capacity cabinet.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a speaker system of the present invention.

FIG. 2 is a diagram for explaining a friction loss of a normal pipeline related to the action of the bent duct of FIG.

FIG. 3 is a diagram for explaining a friction loss of a normal pipeline related to the action of the bent duct of FIG.

FIG. 4 is a diagram showing a result obtained based on various conditions in the bent duct of FIG.

FIG. 5 is a diagram showing a relationship between duct volume and loss obtained under various conditions.

FIG. 6 is a diagram showing a relationship between duct volume and Reynolds number obtained under various conditions.

FIG. 7 is a diagram showing duct volume-velocity relationships obtained under various conditions.

FIG. 8 is a diagram showing a relationship between duct volume and resistance obtained under various conditions.

FIG. 9 is a diagram showing various conditions for obtaining a sound pressure from the port of FIG.

10 is a diagram showing a result of obtaining sound pressure from the port in FIG. 1 according to various conditions.

FIG. 11 is a cross-sectional view showing another embodiment in which a folding duct is provided inside the cabinet.

FIG. 12 is a cross-sectional view showing an example of a conventional bass reflex type cabinet.

FIG. 13 is a cross-sectional view showing another example of a conventional bass reflex type cabinet.

FIG. 14 is a diagram showing an example of a characteristic that is a basis for increasing conventional low-range sensitivity.

FIG. 15 is a diagram showing another example of a characteristic that is a basis for increasing the conventional low-range sensitivity.

[Explanation of symbols] 1 cabinet 2 speaker unit 4 sound absorbing material 8, 8A bending duct 9a port

Claims (2)

[Claims] 1. A speaker system for radiating a part of a sound emitted from the back surface of a speaker provided inside a cabinet to the outside of the cabinet via a bass reflex duct, wherein the bass reflex duct is located on the outer back side of the cabinet or A speaker system characterized in that the speaker system is drawn out from the side surface to the outside front side. 2. A speaker system in which a part of the sound radiated from the back surface of the speaker is radiated to the outside of the cabinet through a bass reflex duct provided inside the cabinet, wherein the volume of the bass reflex duct is Vp, and The dimension of the bass reflex duct when the volume of the cabinet is Vc and the resonance frequency of the bass reflex duct is constant is determined according to the following condition: Vc × 0.05 <Vp <Vc × 0.15. And speaker system.