Speaker box

Abstract

[Problem] To provide a speaker box that suppresses an increase in cost and can be adapted to the installation environment. [Solution] A frame 30 surrounds at least one section of an internal space SP of a speaker box 20, a baffle 21 to which a speaker unit 10 is attached is provided to a front section of the frame 30, and a rear panel 22 is provided to a rear section of the frame 30. A facing set of side panels 23 and a set of a top panel 25 and a bottom panel 26 are provided to side sections of the frame 30. Tension rods 51, 53, 55 and nuts 52, 54, 56 that threadedly engage therewith can apply pressure to the baffle 21 and the rear panel 22, to the set of side panels 23, 24, and to the top panel 25 and the bottom panel 26, in directions in which the intervals between the panels are narrowed, and can change the pressure. The volume of the internal space SP thereby changes so as to decrease, and thus the natural frequency of the speaker box 20 also changes, and it is possible to change the standing wave generation frequency.

Description

speaker box

[0001] The present invention relates to a speaker box having a space capable of accommodating the rear side of a speaker unit. In this specification, a speaker box with a speaker unit attached may be referred to simply as a "speaker." Furthermore, the term "deformation" in this specification refers to elastic deformation, which returns to its original shape substantially when pressure (external force) is no longer applied, and does not include plastic deformation, which does not return to its original shape after deformation.

[0002] A speaker box, also known as a cabinet or enclosure, is a speaker system (speaker) that is made up of speaker units attached to its baffle. Speakers are used by connecting them to audio equipment such as audio amplifiers. Therefore, while speakers have a significant impact on the acoustic characteristics of the room in which they are placed, the sound heard by a listener in the room is not only the direct sound transmitted directly from the speaker, but also the reflected sound that is transmitted by the ceiling, walls, and floor of the room.

[0003] Therefore, it is believed that by tuning speakers and audio equipment to suit the installation environment of the speakers, such as the room in which the speakers are placed, listeners will be able to hear sound that matches that installation environment. For example, the website of Non-Patent Document 1 listed below presents this issue and proposes a solution, which involves understanding the current situation through measurements and correcting room acoustics.

[0004] It is also known that the frequency characteristics of standing waves that may occur inside a speaker box vary depending on the installation environment, as disclosed in Patent Document 1 below. This document discloses a technology that can reduce harmful frequency sounds such as standing waves by attaching a sound-absorbing material with an EA effect to the inside of the speaker box and adjusting the voltage applied to the sound-absorbing material.

[0005] According to Patent Document 1, the EA effect is a phenomenon in which solid particles that have undergone dielectric polarization due to the application of an electric field are coordinately linked to each other in the direction of the electric field, aligning to form a chain structure, or in which some solid particles undergo electrophoresis, aligning to form an arranged block structure (Patent Document 1; paragraphs 0004, 0018 to 0023, etc.).

[0006] "The Light Side of Audio: OrdinarySound / Standing Wave Countermeasures: Essential Issues to Solve to Hear the Original Speaker Sound," [online], OrdinarySound, Home > Audio > Room Acoustics >, [Retrieved June 4, 2023], Internet [https: / / ordinarysound.com / post-1068 / ]

[0007] Japanese Patent Application Publication No. 8-140172

[0008] However, among the solutions proposed on the website of Non-Patent Document 1, the current status assessment by measurement requires room acoustic measurements using specific equipment (such as a measurement microphone and measurement software). Furthermore, room acoustic correction uses an audio equalizer. Therefore, in order to implement such a solution, it is necessary to prepare these devices, which results in a significant increase in the cost of the equipment.

[0009] Furthermore, sound-absorbing materials with EA effects such as those disclosed in Patent Document 1 are not yet widely used. Furthermore, since a DC voltage capable of changing the electric field must be applied to such sound-absorbing materials, a variable power supply capable of varying the output voltage is essential. Therefore, speaker boxes equipped with such sound-absorbing materials and variable power supplies have the problem of increased production costs.

[0010] The present invention has been made to solve the above-mentioned problems, and has an object to provide a speaker box that can suppress an increase in cost and can be adapted to the installation environment.

[0011] To achieve the above object, the present invention employs the technical means described in claim 1. According to this means, the speaker box of the present invention has an internal space capable of accommodating the rear side of a speaker unit, and includes a frame, a front panel, a rear panel, multiple side panels, and a variable pressure member. The frame encloses at least a portion of the internal space, and the front panel to which the speaker unit is attached is provided at the front of the frame, and the rear panel is provided at the rear of the frame. A pair of opposing side panels (one side panel and the other side panel) are provided on the sides of the frame. The variable pressure member can apply pressure or attraction (hereinafter referred to as "pressure, etc.") to the pair of opposing panels in a direction narrowing the gap between the panels, and can change the pressure, etc. The variable pressure member can, for example, be a bolt with an axial length longer than the gap between the pair of opposing panels, and a nut threaded onto the bolt.

[0012] For example, if the speaker box has a rectangular parallelepiped shape and the frame is configured like the sides of the box, the set of side panels would be the right side panel (one side panel (or another side panel)) and the left side panel (the other side panel (or one side panel)), or the top panel (one side panel (or another side panel)) and the bottom panel (the other side panel (or one side panel)). For example, if the speaker box has a cylindrical shape and the frame is configured like the sides of a cross section (rectangular) of the cylinder cut along its central axis, the set of side panels would be the right side panel (one side panel (or another side panel)) and the left side panel (the other side panel (or one side panel)), which have a semi-cylindrical shape. The terms left, right, top, and bottom refer to the relative positions of the front panel when viewed from the front (or the rear panel when viewed from the back). In these cases, the variable pressure member can change the pressure, etc., in a direction that narrows the gap between the right and left panels, or in a direction that narrows the gap between the top and bottom panels. Also, the pressure can be changed in a direction that narrows the gap between the front and rear plates.

[0013] Therefore, when the space between the opposing plates narrows due to pressure applied by the variable pressure member, the internal space of the speaker box changes so that its volume decreases, and the natural vibration frequency (hereinafter referred to as the "natural frequency") of the speaker box also changes. This makes it possible to change the natural frequency of the speaker box by changing the pressure applied by the variable pressure member, thereby changing the frequency at which standing waves occur (resonance frequency) when the speaker unit vibrates at this natural frequency. It also makes it possible to change the reverberation characteristics of sound emitted from the rear (back, underside) of the speaker unit, as it reverberates off one side panel, the other side panel, and the rear panel.

[0014] The present invention also employs the technical means of claim 2. According to this means, the frame has a groove that can surround the periphery of the side of at least one of the front plate, rear plate, one side plate, and other side plate, and can receive part or all of the periphery. Alternatively, the frame has a groove that can abut against the inner surface of the periphery of at least one of the front plate, rear plate, one side plate, and other side plate, and can receive part or all of the periphery. The variable pressure member can attach at least one plate to the frame by applying pressure or the like to the at least one plate and the opposing plate, and can detach at least one plate from the frame by not applying pressure or the like.

[0015] At least one of the front plate, rear plate, one side plate, and other side plate has its side surface surrounded by the frame body or the inner surface of the side surface abutting the frame body, and part or all of the periphery of the one plate is received in a groove in the frame body. Furthermore, the one plate and the opposing plate can be attached to the frame body by applying pressure or the like from a variable pressure member, and can be removed from the frame body by not applying pressure or the like from the variable pressure member. This makes it possible to easily attach or remove at least one of the front plate, rear plate, one side plate, and other side plate depending on whether or not pressure or the like from the variable pressure member is applied, thereby simplifying the work of replacing the one plate.

[0016] The present invention also employs the technical means of claim 3. According to this means, one or more of the front, rear, one side, and other side panels are made of a material that is partially or entirely different from the remaining panels. The front, rear, one side, and other side panels may all be made of the same material, or some of the panels may be made of different materials. Typically, when vibration is applied, hard panels (e.g., metal, glass, ceramic, natural stone, artificial stone, concrete, hard resin) produce high-pitched sounds, while soft panels (wood (e.g., veneer, laminated wood, plywood, particle board, etc.), soft resin) produce low-pitched sounds. The natural frequency of a panel also varies depending on its hardness. By constructing one or more of the front, rear, one side, and other side panels from a different material than the remaining panels, it is possible to change the sound emitted from the side and rear panels by vibrations transmitted from the speaker unit attached to the front panel and how that sound resonates, and it is also possible to change the reverberation characteristics of sound emitted from the back of the speaker unit reverberating in the one side panel, the other side panel, and the rear panel.Furthermore, by constructing part of the side and rear panels from a different material from the remaining parts, it is possible to further change the variation in the sound emitted from the side and rear panels and how that sound resonates.

[0017] The present invention also employs the technical means of claim 4. According to this means, one or more of the front panel, rear panel, one side panel, and other side panel have a thickness that is different from that of the remaining panels. The front panel, rear panel, one side panel, and other side panels may all be of the same thickness, or some of them may have different thicknesses from the remaining panels. Typically, even panels made of the same material produce higher-pitched sounds when vibration is applied, while thicker panels produce lower-pitched sounds. Their natural frequencies also change. By configuring the thickness of one or more of the front panel, rear panel, one side panel, and other side panels to be different from that of the remaining panels, it is possible to change the sound and its resonance from the side panels and rear panels due to vibrations transmitted from the speaker unit attached to the front panel, and it is also possible to change the reverberation characteristics of sound emitted from the rear of the speaker unit reverberating off the one side panel, other side panel, and rear panel. Furthermore, by configuring parts of the side panels or rear panels with different thicknesses from the remaining parts, it becomes possible to further vary the sound emitted from the side panels or rear panels and the way that sound resonates.

[0018] According to the first aspect of the present invention, the natural frequency of the speaker box can be changed by varying the pressure applied by the variable pressure member, thereby changing the frequency (resonance frequency) of standing waves that may occur when the speaker unit vibrates at this natural frequency. Furthermore, the reverberation characteristics of sound emitted from the rear (back or back) of the speaker unit, which reverberates off one side panel, the other side panel, or the rear panel, can also be changed. Therefore, a speaker composed of such a speaker box and speaker unit can be easily tuned to suit the installation environment by adjusting the pressure applied by the variable pressure member. Furthermore, since the variable pressure member is, for example, a bolt and a nut with an axial length longer than the distance between a pair of opposing panels, it is not costly. This reduces costs and allows the speaker to adapt to the installation environment.

[0019] In the invention of claim 2, at least one of the front panel, rear panel, one side panel, and the other side panel can be easily attached or detached depending on the presence or absence of pressure from the variable pressure member, which simplifies the work of replacing that one panel. Therefore, not only can the panel be adapted to the installation environment, but it can also be easily replaced with one that is suitable for the type of music or sound source, such as classical, jazz, rock, or pop, making it possible to easily provide a sound that matches the preferences of the speaker user (hereinafter referred to as the "listener").

[0020] In the invention of claim 3, by configuring one or more of the front panel, rear panel, one side panel, and other side panel to be made of a different material from the remaining panels, it is possible to change the sound emitted from the side panels and rear panels and how it resonates due to vibrations transmitted from the speaker unit attached to the front panel. Furthermore, by configuring part of the side panels and the rear panels from different materials from the remaining parts, it is possible to further change the variety of the sound emitted from the side panels and how it resonates. Therefore, the texture of the sound emitted from the speaker can be matched to the listener's preferences.

[0021] In the invention of claim 4, by configuring the thickness of one or more of the front panel, rear panel, one side panel, and other side panel to be different from the thickness of the remaining panels, it is possible to change the sound emitted from the side panels and rear panels and how it resonates due to vibrations transmitted from the speaker unit attached to the front panel. Furthermore, by configuring some of the side panels and the rear panels with different thicknesses from the remaining panels, it is possible to further change the variation in the sound emitted from the side panels and how it resonates. Therefore, the texture of the sound emitted from the speaker can be matched to the listener's preferences.

[0022] FIG. 2A is a perspective view showing an example of the configuration of a speaker box according to one embodiment (part 1) of the present invention. FIG. 2A is a cross-sectional view of the cross section taken along the dashed-dotted line in the Y direction in FIG. 1, as viewed from the direction of arrow 2A. FIG. 2B is a cross-sectional view of the cross section taken along the dashed-dotted line in the Y direction in FIG. 1, as viewed from the direction of arrow 2B. FIG. 3A is a cross-sectional view of the cross section taken along the dashed-dotted line in the X-axis direction in FIG. 1, as viewed from the direction of arrow 3A. FIG. 3B shows the cross-sectional view with the side panels and other components compressed by tension rods. FIG. 5A is an exploded perspective view showing an example of the frame, baffle, rear panel, and side panels that make up the speaker box according to embodiment (part 1). FIG. 5B to FIG. 5E are schematic cross-sectional views showing variations of the top panel configuration. FIG. 6A is a plan view of the speaker box, and FIG. 6B is a partial cross-sectional view of the cross section taken along the dashed-dotted line, as viewed from the direction of arrow 6B. FIGS. 6(C), 6(E), and 6(G) are plan views showing variations of speaker box configurations, and FIGS. 6(D), 6(F), and 6(H) are partial cross-sectional views of the cross sections taken along the dashed dotted lines, as viewed from the directions of arrows 6D, 6F, and 6H, respectively. In these figures, the gray portion represents the top panel. This is a schematic diagram showing a configuration example of a speaker box according to another embodiment (No. 2) of the present invention. FIG. 7(A) is a perspective view of the speaker box, and FIG. 7(B) is an exploded perspective view of the speaker box. In these figures, the gray portions represent the baffle, rear panel, and side panels. This is a schematic diagram showing a configuration example of a speaker box according to another embodiment (No. 3) of the present invention. FIG. 8(A) is a perspective view of the speaker box, and FIG. 8(B) is an exploded perspective view of the speaker box. In these figures, the gray portions represent the baffle, rear panel, and side panels. This is a schematic diagram showing a configuration example of a speaker box according to another embodiment (No. 4) of the present invention. Figure 9(A) is a perspective view of the speaker box, Figure 9(B) is an exploded perspective view of the speaker box, and Figure 9(C) is a front view of the speaker box. In these figures, the parts colored gray represent the baffle, rear panel, and side panels.1 is an explanatory diagram showing the configuration of a measurement system for measuring the frequency characteristics of the sound pressure level of a sound output from a speaker configured with a speaker box of embodiment (1); FIG. 2 is a characteristic diagram showing an example of the frequency characteristics of the sound pressure level of a sound output from a speaker when each panel of the speaker box of embodiment (1) is configured with a plywood veneer; FIG. 3 is a characteristic diagram showing an example of the frequency characteristics of the sound pressure level of a sound output from a speaker when each panel of the speaker box of embodiment (1) is configured with an aluminum plate; FIG. 4 is a characteristic diagram showing an example of the frequency characteristics of the sound pressure level of a sound output from a speaker when each panel of the speaker box of embodiment (1) is configured with an acrylic plate; FIG. 5 is a characteristic diagram comparing the frequency characteristics of the sound pressure level of a sound output from a speaker configured with a speaker box of embodiment (1) for each panel material.

[0023] An embodiment of a speaker box of the present invention will be described below with reference to the drawings. First, as one embodiment of the speaker box of the present invention, the configuration of a typical sealed speaker box 20 having a rectangular parallelepiped shape will be described as an example. Note that a coordinate system may be shown in the drawings, and the X-axis direction in the coordinate axis display may be referred to as the "width direction" or "left-right direction," the Y-axis direction as the "depth direction" or "front-rear direction," and the Z-axis direction as the "height direction" or "up-down direction."

[0024] As shown in Figures 1 to 3, the speaker box 20, to which the speaker unit 10 is attached, constitutes the speaker 2, and is primarily composed of a baffle 21, a rear panel 22, side panels 23 and 24, a top panel 25, and a bottom panel 26, a frame 30 to which these six panels 21 to 26, including the baffle 21, are attached, and three tension rods 51, 53, and 55. The speaker unit 10 is typically a full-range type, and while the description here uses an example in which there is one speaker unit 10, it may be configured with two units, including a woofer and tweeter, or with three or more units, including a squawker or the like. Note that Figures 2 and 3 show a simplified representation of the speaker unit 10, and therefore do not show the electrical wiring and terminals connected to it.

[0025] The baffle 21 is a rectangular flat plate member that can be attached to the front of the speaker box 20, and is made of, for example, a wooden material with approximately the same thickness across its entire surface. Because the baffle 21 must stably attach the speaker unit 10, it is made of a relatively thick plate material (e.g., laminated wood, plywood, particle board, etc.) and has unit holes 21a formed therein to allow the speaker unit 10 to be attached. While this embodiment (hereinafter referred to as "Embodiment (1)") illustrates a configuration in which one speaker unit 10 can be attached, the baffle 21 may have unit holes 21a in multiple locations corresponding to the number of speaker units 10. The baffle 21 may also have openings for a bass reflex port or a horn.

[0026] In this embodiment (part 1), rod holes 21b are formed in the baffle 21. The rod holes 21b allow tension rods 51 to pass through them, and their inner diameter is set to be slightly larger than the shaft diameter of the tension rods 51. The rod holes 21b are formed in positions where the tension rods 51 inserted therethrough will not come into contact with the speaker units 10 attached to the unit holes 21a. Note that unillustrated through-holes are formed near the four corners of the baffle 21, through which wood screws 57, described below, can be inserted.

[0027] The rear panel 22 is a rectangular flat plate member that can be attached to the back surface so as to face the baffle 21. It is sometimes called a rear baffle, in which case the baffle 21 is called a front baffle. In this embodiment (No. 1), the rear panel 22 has the same outer peripheral shape as the baffle 21, but the speaker unit 10 cannot be attached to it. Therefore, although it differs from the baffle 21 in that it does not have a unit hole 21a, it does have a rod hole 22a formed in approximately the same position as the baffle 21. This rod hole 22a also allows the tension rod 51 to be inserted therethrough, and its inner diameter is set slightly larger than the shaft diameter of the tension rod 51.

[0028] In this embodiment (part 1), the rear panel 22 is made of, for example, a wood material (such as a single board, laminated wood, plywood, or particle board) that is thinner than the baffle 21 and has a substantially uniform thickness across the entire surface (see FIG. 2 ). Therefore, as will be described later, when pressure is applied by the tension rods 51 and their nuts 52, the rear panel 22 deforms, bending inward toward the speaker box 20 in accordance with the applied pressure. In this embodiment (part 1), the rear panel 22 is made of a thin wood material, but it may also be made of a thick wood material or a material harder than wood, such as metal, glass, ceramic, natural stone, artificial stone, concrete, or hard resin. In these cases, the rear panel 22 is less likely to deform than when made of a thin wood material.

[0029] The tension rod 51 is a long-shaft bolt whose axial length is set longer than the size of the speaker box 20 in the depth direction (front-to-back direction). For example, one end 51a of the tension rod 51 has a pan-head screw head, and the other end 51b has a male thread. A nut 52 that can be threaded onto the male thread on the other end 51b of the tension rod 51 is threadedly coupled to the tension rod 51, thereby narrowing or widening the separation distance (between the plates) between the baffle 21 and rear panel 22 attached to the frame 30. The tension rod 51 may also be a cut bolt (long screw) without a screw head on the one end 51a. In this case, a male thread is also formed on the one end 51a, and the nut 52 is threaded onto it.

[0030] The side panels 23, 24 are rectangular, flat plate members that can be attached to the left and right sides of the speaker box 20 in opposing positions, and, like the rear panel 22, are made of, for example, a thin, uniformly thick wooden material across the entire surface. In this embodiment (part 1), the side panels 23, 24 have the same shape and are constructed identically. Rod holes 23a, 24a are formed in the approximate centers of the side panels 23, 24. The rod holes 23a, 24a allow the tension rod 53 to pass through, and their inner diameters are set slightly larger than the shaft diameter of the tension rod 53.

[0031] The top panel 25 is a square, flat plate member that can be attached to the top surface of the speaker box 20, and is sometimes called a ceiling plate. Like the side panels 23 and 24, the top panel 25 is made of, for example, a thin wooden material that is approximately the same thickness across its entire surface, and has a rod hole 25a formed in its approximate center. This rod hole 25a allows the tension rod 55 to pass through, and its inner diameter is set slightly larger than the shaft diameter of the tension rod 55.

[0032] The bottom panel 26 is a square-shaped flat plate member that can be attached to the underside of the speaker box 20 so as to face the top panel 25, and is sometimes referred to as a bottom plate. In this embodiment (No. 1), the bottom panel 26 has the same outer peripheral shape as the top panel 25, but unlike the side panels 23, 24 and the top panel 25, it is made of a relatively thick plate material (e.g., laminated wood, plywood, particle board, etc.) like the baffle 21 (its thickness is approximately the same across the entire surface). This is because it can suppress twisting and distortion of the frame 30 in the left-right and front-to-back directions, and can increase the weight ratio of the speaker box 20 downward, improving stability when placed.

[0033] Similar to the baffle 21, unillustrated through-holes through which wood screws 57 can be inserted are formed near the four corners of the rear panel 22, the side panels 23 and 24, the top panel 25, and the bottom panel 26. Similarly to the rear panel 22, the side panels 23 and 24 and the top panel 25 may be made of a plate material harder than wood, such as metal, glass, ceramic, natural stone, artificial stone, concrete, or hard resin, in which case these panels 23 to 25 will be less likely to deform than if they were made of a thinner wooden plate.

[0034] The tension rod 53 is a long-shaft bolt whose axial length is set longer than the width (left-right) dimension of the speaker box 20. The tension rod 55 is also a long-shaft bolt whose axial length is set longer than the height (up-down) dimension of the speaker box 20. As with the tension rod 51, for example, one end 53a of the tension rod 53 is formed with a pan head screw head, and the other end 53b is formed with a male thread. Furthermore, one end 55a of the tension rod 55 is formed with a countersunk head screw head, and the other end 55b is formed with a male thread.

[0035] Nuts 54, 56 that can be threaded onto the male threads on the other ends 53b, 55b of these tension rods 53, 55 function to narrow or widen the separation distance (between the panels) between the left and right side panels 23, 24 and the upper and lower top and bottom panels 25, 26 attached to the frame 30. The tension rods 53, 55 may also be cut bolts (long threads) like the tension rod 51, in which case a male thread is also formed on one end 53a onto which the nut 54 is threaded.

[0036] Wood screws 57 are used to secure the six panels 21 to 26, including the baffle 21, to the frame 30. The wood screws 57 may have either pan head or countersunk head screws. However, it is desirable that the screws that secure the bottom panel 26 have countersunk head screws, just like the tension rods 55. This is because the bottom panel 26 of the speaker box 20 may come into direct contact with the floor surface on which the speaker 2 is installed, and therefore it is desirable that it has a flat surface with no protrusions.

[0037] Note that if the baffle 21 and rear panel 22 can be attached and fixed to the frame 30 using tension rods 51, the wood screws 57 are not necessarily required. Also, if the side panels 23, 24 can be attached and fixed to the frame 30 using tension rods 53, the wood screws 57 are not necessarily required. Furthermore, if the top panel 25 and bottom panel 26 can be attached and fixed to the frame 30 using tension rods 55, the wood screws 57 are not necessarily required. In these cases, the wood screws 57 can be omitted.

[0038] The detailed configuration of the frame 30 is shown in FIG. 4 . Therefore, the following description will be made with reference to FIG. 4 . As shown in FIG. 4 , the frame 30 is composed of 12 rectangular pillar-shaped segments (hereinafter referred to as "segments") 31-42, and these segments 31-42 are configured to form the sides of the speaker box 60, which has a rectangular parallelepiped shape. Specifically, for example, square lumber is used, whose cross-sectional shape in the thickness direction has sides of a predetermined length. The "predetermined length" is a length sufficiently longer than the thickness of the six panels 21-26, such as the baffle 21. For example, the length is equivalent to two to three times the thickness of the baffle 21 or bottom panel 26, which has the largest thickness among these six panels 21-26.

[0039] The front portion, or front section, of the frame 30 is composed of four segments 31 to 34 that can form a rectangular frame that is slightly larger than the baffle 21 attached thereto. That is, when viewed from the front of the speaker box 20, the segment 31 located on the upper left-right direction, the segment 32 located on the lower left-right direction, the segment 33 located on the left-upward direction, and the segment 34 located on the right-upward direction are combined to form a rectangular frame, thereby forming the front section of the frame 30. Since the baffle 21 described above is attached to this front section, notched grooves 31a to 34a with an L-shaped cross section and a depth equivalent to the plate thickness of the baffle 21 are formed on the front side of the rectangular column shape of the segments 31 to 34, respectively, along the longitudinal direction of the square material (see FIGS. 2 and 4).

[0040] The rear portion of the frame 30, i.e., the rear section, is composed of four segments 35-38 that form a rectangular frame that is slightly larger than the rear panel 22 to which it is attached. In this embodiment (part 1), because the baffle 21 and the rear panel 22 have the same outer peripheral shape, the rectangular frame of this rear section is configured substantially identically to the rectangular frame of the front section of the frame 30 that is composed of the segments 31-34. That is, when viewed from the front of the speaker box 20, the rear section of the frame 30 is configured by combining the segment 35 located on the upper left-right direction, the segment 36 located on the lower left-right direction, the segment 37 located on the left-upper side, and the segment 38 located on the right-upper side to form a rectangular frame. In this rear section, notched grooves 35a-38a similar to the segments 31-34 are formed along the longitudinal direction on the rear side of the rectangular column-shaped segments 35-38 (see Figures 2 and 4).

[0041] The left side portion of frame 30, i.e., the left side section, is composed of two segments 39, 40, segment 33 constituting the front section of frame 30, and segment 37 constituting the rear section, so as to form a rectangular frame that is slightly larger than side panel 23 to be attached thereto. That is, in addition to front segment 33 and rear segment 37, segment 39 located on the upper left side in the front-to-rear direction when viewed from the front of speaker box 20 and segment 40 located on the lower left side in the front-to-rear direction are combined to form a rectangular frame, thereby forming the left side section of frame 30. On this left side section, notched grooves 33b, 37b, 39a, and 40a similar to segments 31 to 34 are formed along the longitudinal direction on the left surfaces of the rectangular pillar shapes of segments 33, 37, 39, and 40, respectively (see FIGS. 2 to 4).

[0042] The right side portion of frame 30, i.e., the right side section, is composed of two segments 41, 42, segment 34 constituting the front section of frame 30, and segment 38 constituting the rear section, so as to form a rectangular frame that is slightly larger than side panel 24 to be attached thereto. That is, in addition to front segment 34 and rear segment 38, segment 41 located on the upper right side in the front-to-rear direction and segment 42 located on the lower right side in the front-to-rear direction when viewed from the front of speaker box 20 are combined to form a rectangular frame, thereby forming the right side section of frame 30. On this right side section, notched grooves 34b, 38b, 41a, and 42a similar to those of segments 31 to 34 are formed along the longitudinal direction on the right surfaces of the rectangular column shapes of segments 34, 38, 41, and 42, respectively (see FIGS. 2 to 4).

[0043] The upper portion of frame 30, i.e., the upper side, is composed of segment 31 constituting the front portion of frame 30, segment 35 constituting the rear portion, segment 39 constituting the left side portion, and segment 41 constituting the right side portion, so as to form a square rectangular frame that is slightly larger than top panel 25 to be attached to it. In other words, the segments 31, 35, 39, and 41 on the front, rear, left, and right sides described so far are combined to form a square rectangular frame, thereby forming the upper side of frame 30. In this upper side, notched grooves 31b, 35b, 39b, and 41b similar to segments 31 to 34 are formed along the longitudinal direction on the upper surfaces of the rectangular column-shaped segments 31, 35, 39, and 41, respectively (see Figures 2 to 4).

[0044] The lower portion of frame 30, i.e., the lower side, is composed of segment 32 constituting the front portion of frame 30, segment 36 constituting the rear portion, segment 40 constituting the left side portion, and segment 42 constituting the right side portion, so as to form a square rectangular frame that is slightly larger than bottom panel 26 to be attached to it. In other words, the segments 32, 36, 40, and 42 on the front, rear, left, and right sides described above are combined to form a square rectangular frame, thereby forming the lower side of frame 30. In this lower side, notched grooves 32b, 36b, 40b, and 42b similar to segments 31 to 34 are formed along the longitudinal direction on the undersides of the rectangular column shapes of segments 32, 36, 40, and 42, respectively (see Figures 2 to 4).

[0045] The assembly configuration at each end of the segments 31 to 42 can be configured so that the segments 31 to 42 are perpendicular to each other, and a common method used in construction methods, etc. For example, this can be done using a mitre joint (a method of attaching a joint to the cross section of a member and joining it to the cross section of another member), a miter joint (a method of processing the joining cross section of a member at a 45-degree angle and joining the cross sections of both members by tightly fitting them together), or a joint (a method of joining members by inserting them together using a joint or dovetail).

[0046] In this embodiment (part 1), notched grooves 31a, 31b, 32a, 32b, 33a, 33b, 34a, 34b, 35a, 35b, 36a, 36b, 37a, 37b, 38a, 38b, 39a, 39b, 40a, 40b, 41a, 41b, 42a, and 42b (hereinafter collectively referred to as "notched grooves 31a to 42b") are formed in each of the segments 31 to 42 so as to fit the baffle 21, rear panel 22, side panels 23 and 24, top panel 25, and bottom panel 26. This allows these six panels 21 to 26 to be attached to the frame 30 in a stable manner without rattling or shifting up and down or left and right relative to the frame 30.

[0047] As described above, the six panels 21-26, including the baffle 21, are fastened to the frame 30 by inserting wood screws 57 into through-holes (not shown) formed near the four corners of each panel and screwing them into the segments 31-42. The tension rod 51 is inserted through the rod hole 21b of the baffle 21 and the rod hole 22a of the rear panel 22, and then a nut 52 is screwed onto the other end 51b of the tension rod 51. The tension rod 51 is then screwed until the baffle 21 and the rear panel 22, which are sandwiched between the screw head of the tension rod 51 and the nut 52, begin to deform. The tension rod 53 inserted into the rod holes 23a, 24a of the side panels 23, 24 and the tension rod 55 inserted into the rod hole 25a of the top panel 25 and the rod hole 26a of the bottom panel 26 are also screwed in the same manner as the tension rod 51.

[0048] In the speaker box 20 of the first embodiment configured as described above, as shown in FIG. 3B , when the tension rod 53 penetrating in the X-axis direction (left-right direction) is tightened, the side panels 23′, 24′ deform (warp) into a concave shape (concave curved surface) so that the space between them narrows (so that they recess toward the inside of the speaker box 20 (internal space SP)). When the tension rod 55 penetrating in the Z-axis direction (up-down direction) is tightened, the top panel 25′ and the bottom panel 26′ also deform into a concave shape so that the space between them narrows. Although not shown in FIG. 3 , when the tension rod 51 penetrating in the Y-axis direction (front-rear direction) is also tightened, the baffle 21 and the rear panel 22 also deform into a concave shape so that the space between them narrows. In the first embodiment, the rear panel 22 and the top panel 25 are thinner than the baffle 21 and the bottom panel 26, and therefore the amount of deformation (warpage) is greater.

[0049] The amount of deformation of the six panels 21 to 26, including the baffle 21, increases when the tension rods 51, 53, and 55 are tightened and decreases when they are loosened. That is, these amounts of deformation can be increased or decreased within a range (predetermined range) from the flat state (minimum value) in which the panels 21 to 26 are not deformed to the maximum amount of deformation (maximum value) of each panel 21 to 26. This adjustment of the amount of deformation using the tension rods 51, 53, and 55 and the nuts 52, 54, and 56 that thread onto them (hereinafter referred to as "tension rods 51, etc.") is most effective when performed while the speaker 2 is connected to an audio device and any music or sound is being output from the speaker unit 10.

[0050] For example, if speaker 2 is installed in a room such as an audio room, a listener can tighten or loosen tension rod 51 while playing music of a genre that suits their taste (e.g., classical, jazz, rock, pop, etc.) from speaker unit 10 of speaker 2. This allows the listener to adjust the amount of deformation of panels 21-26 while checking with their own ears the materials and structures of the walls, ceiling, floor, etc. that make up the room, and the way the sound resonates that suits the music, genre, etc. Therefore, the listener can adjust speaker 2 to emit sound that matches their taste, including not only the direct sound transmitted directly from speaker 2 but also the reflected sound that is transmitted by being reflected by the ceiling, walls, and floor.

[0051] As described above, in the speaker box 20 of this embodiment (part 1), the frame 30 surrounds the rectangular parallelepiped internal space SP of the speaker box 20 as its sides, and segments 31 to 34 (the front of the frame) of the frame 30 are provided with a baffle 21 to which the speaker unit 10 is attached, and segments 35 to 38 (the rear of the frame) are provided with a rear panel 22. In addition, a pair of opposing side panels 23 and 24 are provided on segments 33, 37, 39, and 40 (the sides of the frame) and segments 34, 38, 41, and 42 (the sides of the frame) of the frame 30, and a pair of opposing top and bottom panels 25 and 26 are provided on segments 31, 35, 39, and 41 (the sides of the frame) and segments 32, 36, 40, and 42 (the sides of the frame). The tension rods 51 and the like can apply pressure to the baffle 21 and rear panel 22, the pair of side panels 23 and 24, and the top panel 25 and bottom panel 26 in a direction that narrows the gap between the panels, and can change the pressure.

[0052] Therefore, when the pressure applied by the tension rods 51 or the like narrows the gap between the baffle 21 and the rear panel 22, the gap between the pair of opposing side panels 23 and 24, or the gap between the top panel 25 and the bottom panel 26, the volume of the internal space SP of the speaker box 20 changes, and the natural frequency of the speaker box 20 also changes. This makes it possible to change the natural frequency of the speaker box 20 by changing the pressure applied by the tension rods 51 or the like, and therefore to change the frequency at which standing waves are generated when the speaker unit 10 vibrates at this natural frequency (resonance frequency). Furthermore, it is possible to change the reverberation characteristics of sound emitted from the rear surface 11 of the speaker unit 10, which reverberates in the rear panel 22, the side panels 23 and 24, the top panel 25, and the bottom panel 26.

[0053] Therefore, the speaker 2 configured with such a speaker box 20 and speaker unit 10 can be easily tuned to suit the installation environment by adjusting the pressure applied by the tension rods 51, etc. Furthermore, since the tension rods 51, etc. consist of the tension rods 51, 53, 55 and the nuts 52, 54, 56 that screw into them, they are not likely to be expensive. This prevents increases in cost and allows the speaker to be adapted to the installation environment.

[0054] Furthermore, in the speaker box 20 of embodiment (1), the frame 30 has notched grooves 31a-42b that can surround the peripheries of the sides of the baffle 21, rear panel 22, side panels 23 and 24, top panel 25, and bottom panel 26 and can accommodate the entire peripheries. The rear panel 22 can be attached to the frame by applying pressure to the baffle 21 and rear panel 22 using tension rods 51 and nuts 52 threaded thereon, and can be removed from the frame 30 by removing pressure. The side panels 23 and 24 can be attached to the frame by applying pressure to the side panels 23 and 24 using tension rods 53 and nuts 54 threaded thereon, and can be removed from the frame 30 by removing pressure. The top panel 25 can be attached to the frame by applying pressure to the top panel 25 and bottom panel 26 using tension rods 55 and nuts 56 threaded thereon, and can be removed from the frame 30 by removing pressure.

[0055] This allows easy attachment and detachment of at least the rear panel 22, the side panels 23 and 24, and the top panel 25 among the baffle 21 and the rear panel 22, the side panels 23 and 24, the top panel 25, and the bottom panel 26, depending on whether or not pressure is applied by the tension rods 51 or the like, thereby simplifying the replacement of these panels 22 to 25. Therefore, not only can the panels 22 to 25 be adapted to the installation environment, but any of these panels 22 to 25 can also be easily replaced with panels made of a material (e.g., veneer, laminated wood, plywood, particle board, metal, glass, ceramic, natural stone, artificial stone, concrete, hard resin) that is suitable for the type of music or sound source, such as classical, jazz, rock, or pop. Therefore, the reverberation characteristics of the sound emitted from the rear surface 11 of the speaker unit 10 and reflected by the rear panel 22, the side panels 23 and 24, the top panel 25, and the bottom panel 26 in the interior space SP of the speaker box 20 can be changed by changing the materials of these panels 22 to 26. Therefore, it is possible to easily provide sounds that match the preferences of the listener.

[0056] Furthermore, in the speaker box 20 of the first embodiment, among the baffle 21, rear panel 22, side panels 23 and 24, top panel 25, and bottom panel 26, for example, the rear panel 22, side panels 23 and 24, and top panel 25 are made of plate materials harder than wood, such as metal, glass, ceramic, natural stone, artificial stone, concrete, or hard resin, and the remaining baffle 21 and bottom panel 26 are made of wood, which is softer than these. Typically, when vibration is applied, hard plates (e.g., metal, glass, ceramic, natural stone, artificial stone, concrete, or hard resin) produce high-pitched sounds, while soft plates (wooden materials (such as veneer, laminated wood, plywood, or particle board), or soft resin) produce low-pitched sounds. Furthermore, the natural frequency of each plate varies depending on its hardness. This makes it possible to change the sound emitted from the rear panel 22, side panels 23 and 24, top panel 25, and bottom panel 26, the way that sound reverberates, and the reverberation characteristics that reverberate from these panels 22 to 26, due to vibrations transmitted from the speaker unit 10 attached to the baffle 21. Therefore, the texture of the sound emitted from the speaker 2 can be matched to the preferences of the listener.

[0057] Furthermore, in the speaker box 20 of the first embodiment, among the baffle 21, rear panel 22, side panels 23 and 24, top panel 25, and bottom panel 26, the rear panel 22, side panels 23 and 24, and top panel 25 have different overall thicknesses compared to the baffle 21 and bottom panel 26. These panels 22 to 25 have thinner overall thicknesses compared to the baffle 21 and bottom panel 26. Typically, when vibration is applied to plates made of the same material, thinner plates produce higher-pitched sounds, while thicker plates produce lower-pitched sounds. Their natural frequencies also change. This makes it possible to change the sound and resonance emitted from the rear panel 22, side panels 23 and 24, top panel 25, and bottom panel 26, as well as the reverberation characteristics of the sound reverberating from these panels 22 to 26, by vibration transmitted from the speaker unit 10 attached to the baffle 21. Therefore, the texture of the sound emitted from the speaker 2 can be tailored to the listener's preferences.

[0058] <<Modification 1>> Note that, in the speaker box 20 of the above-described embodiment (part 1), the baffle 21, rear panel 22, side panels 23 and 24, top panel 25, and bottom panel 26 have been described as being configured so that the thicknesses of their entire surfaces are substantially the same, but, for example, the thickness of at least one (or six) of the six panels 21 to 26, including the baffle 21, may be made thinner or thicker in part of the entire surface. In other words, the panel may be configured so that the thickness of parts of the entire panel is different.

[0059] Taking the top panel 25 as an example, as shown in FIG. 5, a top panel 25w may be configured in which the thickness of almost the entire surface is reduced by forming a recess 27 except for the area around the rod hole 25a in the area α surrounded by the dashed line in FIG. 5(A) (see FIG. 5(B)). The area around the rod hole 25a is excluded in order to increase the mechanical strength of the area around the rod hole 25a. Alternatively, a top panel 25x may be configured in which the thickness of a portion of the top panel is reduced by forming a recess 27 except for the area around the rod hole 25a in approximately half of the area in the left-right or front-back direction (see FIG. 5(C)). Furthermore, a top panel 25y may be configured in which a plurality of recesses 28 are formed in the remaining approximately half of the area of ​​the top panel 25x shown in FIG. 5(C) where the recess 27 is not formed (see FIG. 5(D)). Alternatively, a top panel 25z may be configured in which recesses 28, 29 of different depths are formed in different positions (see FIG. 5(E)).

[0060] As a result, for example, at least one of the six panels 21 to 26 of the baffle 21 has thin and thick portions in a portion thereof, and compared to when the entire surface of at least one panel is the same thickness, it is possible to vary in a more diverse and complex manner the sound emitted from the rear panel 22, side panels 23 and 24, top panel 25, and bottom panel 26, the way that sound reverberates, and the reverberation characteristics of the sound reverberating from these panels 22 to 26, due to the vibrations transmitted from the speaker unit 10 of the baffle 21. This not only prevents increases in cost and allows the speaker 2 to be adapted to the installation environment, but also allows the texture of the sound emitted from the speaker 2 to be more precisely matched to the listener's preferences.

[0061] Furthermore, because the thinner portions where the recesses 27, 28 are formed are more susceptible to deformation than the thicker portions when pressurized by the tension rods 51, etc., it is possible to control the portions that deform due to tightening or loosening of the tension rods 51, etc., based on the positions of the recesses 27, 28. Although not shown, rib (skeletal) material may be provided in the X-axis or Y-axis direction within the recesses 27, 28 or in portions where the recesses 27 are not formed. This increases the mechanical rigidity of the portions where the rib material is present, so that by changing the position and number of the rib material, it is possible to control the portions that deform due to tightening or loosening of the tension rods 51, etc., and to vary in a diverse and complex manner the sound emitted from the rear panel 22, the side panels 23, 24, the top panel 25, and the bottom panel 26, the way that the sound resonates, and the reverberation characteristics that reverberate in these panels 22-26.

[0062] <<Modification 2>> Furthermore, in the speaker box 20 of the above-described embodiment (part 1), the frame 30 has been described as having cutout grooves 31a-42b that can surround the peripheries of the sides of the baffle 21, rear panel 22, side panels 23 and 24, top panel 25, and bottom panel 26 and can accommodate the entire periphery. An example of this using panel 25 is shown in Figures 6(A) and 6(B). Note that the dashed dotted line indicating the cut portion in Figure 6(A) extends from the left of the page along the Y axis to point β, and then extends upward along the X axis, resulting in an irregular cross-sectional view in Figure 6(B).

[0063] That is, in the speaker box 20 of the first embodiment, for example, the segments 31, 35, 39, and 41 constituting the frame 30 have notched grooves 31b, 35b, 39b, and 41b that accommodate the periphery of the top panel 25 and surround the periphery of the side of the top panel 25. However, for example, the segments 39 and 41 located in the Y-axis direction (front-to-back direction) may be configured without notched grooves 39b and 41b. That is, as shown in Figures 6(C) and 6(D), the frame 130 may be configured with notched grooves 31a and 35b that can surround the periphery of the side of the top panel 125 and accommodate a portion of the periphery. Note that Figure 6(D) shows an irregular cross-sectional view, similar to Figure 6(B).

[0064] In this configuration, the segments 139 and 141 do not have the notched grooves 39b and 41b. As a result, the side surfaces 139b and 141b of the segments 139 and 141 protrude inward by that amount, and the width of the top panel 125 in the X-axis direction (left and right direction) is smaller than that of the top panel 25 described above. As a result, the segments 31 and 35 surround the periphery of the side surface of the top panel 125 along the Y-axis, and the segments 139 and 141 abut against the side surface of the top panel 125 along the X-axis. In other words, the frame 130 formed by the segments 31, 35, 139, and 141 is configured to have the notched grooves 31b and 35b that can surround the periphery of the side surface of the top panel 125 and can receive part of the periphery of the top panel 125. As a result, both side portions of the top panel 125 in the X-axis direction (left-right direction) are more likely to deform (warp) and sink toward the internal space SP than both side portions in the Y-axis direction (front-back direction) that are fitted with the cutout grooves 31b and 35b, since they do not have the cutout grooves. Note that, contrary to this example, the frame segments may be configured to have the cutout grooves 39b and 41b without the cutout grooves 31b and 35b.

[0065] 6(E) and 6(F), for example, the periphery of the top panel may be configured with an inverted L-shape (top panel 225). In this case, grooves 239a, 235a, 241a, and 231a are formed in the segments 239, 235, 241, and 231 of the frame 230 to accommodate the protruding ends 225a, 225b, etc., of the top panel 225. These grooves 239a, etc. are configured so that their inner wall portions 239b, 235b, 241b, and 231b are lower than the outer wall portions by the thickness of the top panel 225 or more. Note that FIG. 6(F) also shows an irregular cross-sectional view, similar to FIG. 6(B).

[0066] By configuring the top panel 225 and the frame 230 in this manner, when the top panel 225 is attached to the frame 230, the periphery and four convex edges 225a, 225b of the top panel 225 fit into the recessed grooves 239a, 235a, 241a, 231a, and the periphery of the side surface of the top panel 225 is surrounded by the segments 239, 235, 241, 231. The inner surface of the periphery of the top panel 225 abuts against the inner wall portions 239b, 235b, 241b, 231b. In other words, the frame 230 formed by the segments 231, 235, 239, 241 is configured to have cutout grooves 231b, 235b, 239b, 241b that can surround the periphery of the side surface of the top panel 225 and can receive the entire periphery of the top panel 225. This increases the degree of sealing between the top panel 225 and the frame 230 compared to the top panel 25 of the speaker box 20 described above, making it possible to prevent sound transmitted through the internal space SP from leaking to the outside.

[0067] Furthermore, as shown in Figures 6(G) and 6(H), for example, the top panel may have a convex shape that protrudes from its inner periphery (top panel 325). In this case, the segments 339, 335, 341, and 331 that make up the frame 330 are formed with recessed grooves 339a, 335a, 341a, and 331a that can accommodate the protrusions 325a, 325b, etc., of the top panel 325. These recessed grooves 339a, etc. are configured so that their inner and outer walls are the same height. Therefore, the top panel 225 in this case has an outer shape that is approximately the same size as the rectangular outline formed by the segments 339, 335, 341, and 331, i.e., its periphery is expanded by the amount of the outer wall of the recessed groove 339a, etc., compared to the top panel 25. Note that Figure 6(H) also shows an irregular cross-sectional view, similar to Figure 6(B).

[0068] By configuring the top panel 325 and the frame 330 in this manner, when the top panel 325 is attached to the frame 330, the convex portions 325a, 325b, etc. on the periphery and four sides of the top panel 325 fit into the recessed grooves 339a, 335a, 341a, 331a, and the inner surface of the periphery abuts against both the inner wall portion and the outer wall portion of the recessed groove 339a, etc. In other words, the frame 330 formed by the segments 331, 335, 339, 341 is configured to have cutout grooves 331b, 335b, 339b, 341b that can abut against the inner surface of the periphery of the top panel 325 and can accommodate the entire periphery of the top panel 325. This increases the degree of sealing between the top panel 325 and the frame 330 compared to the top panel 25 of the speaker box 20 described above, making it possible to suppress sound transmitted through the internal space SP from leaking to the outside. Additionally, the top panel 325 hides the frame 330, which may improve the appearance and enhance the aesthetics.

[0069] In the configuration examples shown in Figures 6(E) and (F) and the configuration examples shown in Figures 6(G) and (H), convex end portions 225a, 225b, etc. and convex portions 325a, 325b, etc. are provided on all four sides of the periphery of the top panel 225, 325. However, as in the configuration examples shown in Figures 6(C) and (D), convex end portions 225b (225a), etc. and convex portions 325b (325a), etc. may be provided only on two sides of the periphery of the top panel 225, 325 along the Y axis (or two sides along the X axis), and the remaining two sides may be narrowed to correspond to the segments 139, 141 without providing convex end portions or convex portions, as with the top panel 125. Furthermore, top panels having any combination of the configurations of the sides of the top panels 25, 125, 225, and 325 may be configured, along with frames having segments 39, 139, 239, 339, etc. that correspond to such top panels.

[0070] Furthermore, while the above-described modified example 2 illustrates the case of the top panel 25, the baffle 21, rear panel 22, side panels 23 and 24, and bottom panel 26 may also be configured in the same manner as the top panels 125, 225, and 325 of modified example 2. In that case, the frame cells also need to be configured in accordance with the baffles, etc., like segments 139, 239, and 339 of modified example 2.

[0071] <<Modification 3>> In the speaker box 20 of the above-described embodiment (part 1), the speaker box of modification 1 (Figure 5), and the speaker box of modification 2 (Figure 6), the six panels 21 to 26 including the baffle 21 are configured to maintain a flat state without warping when there is no pressure due to tightening force from the tension rod 51 or the like, but the four panels 22 to 25 excluding the baffle 21 and the bottom panel 26 may be configured, for example, as follows.

[0072] That is, in the absence of pressure from the tightening of tension rods 51 or the like, the rear panel, two side panels, and top panel corresponding to the four panels 22 to 25 may be deformed in advance so as to maintain a convex curved shape with their approximate centers bulging outward from the speaker box 20. The tension rod corresponding to tension rod 51 is set so that its axial length is longer than the distance between the baffle and the convexly curved rear panel, and the tension rod corresponding to tension rod 53 is set so that its axial length is longer than the distance between the two convexly curved side panels. The tension rod corresponding to tension rod 55 is set so that its axial length is longer than the distance between the bottom panel and the convexly curved top panel. Because the baffle 21 needs to stably hold the speaker unit 10, and the bottom panel 26 needs to mechanically stabilize the speaker box 20 on the installation surface, it is desirable for them to maintain flat surfaces in the absence of pressure from tension rods 51 or the like.

[0073] As a result, when there is no pressure from tension rods and nuts corresponding to tension rods 51 or the like, these four panels have a convex curved shape (convex) in which approximately their centers bulge outward from the speaker box 20. When a predetermined pressure is applied by tightening the tension rods, these panels assume a planar shape with a flat surface without warping. Then, as the tension rods are further tightened and pressure exceeding this predetermined pressure is applied, these four panels deform (warp) so as to be concave toward the inside of the speaker box 20, i.e., they deform (warp) into a concave curved shape (concave), as shown in Figure 3(B). Therefore, the amount of deformation of these four panels can be increased or decreased within a range from a convex state (maximum positive value) in which these panels are deformed into a convex curved shape to a concave state (maximum negative value) in which these panels are deformed into a concave curved shape.

[0074] In this way, in the speaker box of Modified Example 3, the range over which the volume of the internal space SP of the speaker box can be increased or decreased is wider than in the speaker box 20 of the above-mentioned embodiment (No. 1), and therefore the range over which the resonance frequency of the standing wave can be varied (adjusted) is also wider. Therefore, the range over which the pressure applied by the tension rod and its nut can be adjusted is wider, making it easier to tune to suit the installation environment and increasing the degree of freedom in tuning, which prevents costs from increasing and allows the speaker box to be adapted to a wide range of installation environments.

[0075] [Other Embodiments] Here, speaker boxes 60, 70, and 80 of other embodiments having a configuration different from the speaker box 20 of the embodiment described above will be described with reference to Figures 7 to 9. Note that the speaker boxes 60, 70, and 80 described here do not have the speaker unit 10 attached, but similar to the speaker box 20 described above, when a speaker is constructed, the speaker unit 10 is attached to the unit holes 63a, 73a, and 84a of the baffles 63, 73, and 84. Note also that the panels of the baffle 63 and the segments 61 shown in these figures are simplified for the purpose of illustration, and plate thicknesses, grooves, and the like are omitted.

[0076] 7A and 7B, a speaker box 60 according to a first embodiment (hereinafter referred to as "Embodiment 2") is a cylindrical, sealed speaker box. Therefore, the speaker box 60 is primarily composed of a circular baffle 63 and rear panel 64, semi-cylindrical side panels 65 and 66, two rectangular pillar-shaped segments 61 and 62, one tension rod 69, and a nut.

[0077] The baffle 63 is, for example, a circular flat plate member having an outer diameter to which the speaker unit 10 described in the above-mentioned embodiment (part 1) can be attached, and is made of a relatively thick wooden material (for example, laminated wood, plywood, particle board, etc.). The baffle 63 is formed with unit holes 63a to which the speaker unit 10 can be attached. The rear panel 64 is a circular flat plate member facing the baffle 63, and is constructed in the same manner as the baffle 63 except that it does not have the unit holes 63a formed therein.

[0078] The side panels 65, 66 are curved plate members having a shape equivalent to a semicylinder obtained by cutting the cylindrical shape of the speaker box 60 in two along its central axis, and their axial length (Y-axis direction) is set to correspond to the axial length of the speaker box 20. The side panels 65, 66 are each formed with rod holes 65a, 66a through which a tension rod 69 can be inserted. In this embodiment (part 2), since there is only one tension rod 69, unit holes 63a, 64a are formed in approximately the center of the axial direction of the side panels 65, 66 at positions where the tension rod 69 can be perpendicular to the central axis of the speaker box 60, that is, at the diametric position in the X-axis direction in Figure 7.

[0079] The side panels 65, 66 are made of, for example, wood material (single board, laminated wood, plywood, particle board, etc.) that is thinner than the baffle 63 and rear panel 64, or a metal plate with excellent spring properties (for example, phosphor bronze plate, etc.). Therefore, when pressure is applied by the tension rod 69 and its nut, the side panels 65, 66 deform so as to be recessed inward of the speaker box 60 according to the pressure, or when pressure is reduced, they bulge outward, approaching (recovering) their shape before pressure was applied.

[0080] The segments 61 and 62 have, for example, a rectangular column shape, and their length is set to correspond to the axial length of the speaker box 60. More specifically, for example, square lumber whose cross section in the thickness direction has sides of a predetermined length is used, and one end of the lumber is connected to the baffle 63 and the other end is connected to the rear panel 64. In this embodiment (part 2), there are two segments 61 and 62, and therefore they are connected to the baffle 63 and the rear panel 64 at half a circumference (180°) apart in the circumferential direction (diameter position in the Z-axis direction in FIG. 7 ).

[0081] The tension rod 69 is a long-shaft bolt having an axial length sufficient to pass through the speaker box in the radial direction (X-axis direction), and like the tension rod 51 of the speaker box 20, has a screw head (not shown) formed on one end and a male thread (not shown) formed on the other end. In this embodiment (part 2), the tension rod 69 is inserted through the rod holes 65a, 66a of the side panels 65, 66, passes through the speaker box 60 in the radial direction, and is then fastened with a nut (not shown) that screws onto the male thread.

[0082] In this way, by connecting the segments 61, 62 to the baffle 63 and the rear panel 64, the segments 61, 62, together with the baffle 63 and the rear panel 64, can correspond to a frame that surrounds at least a portion of the internal space SP of the speaker box 60, that is, a frame having four sides of a rectangular cross section obtained by cutting the cylindrical shape of the speaker box 60 along its central axis. Although not shown in Figure 7, the segments 61, 62 each have a notch groove formed along the longitudinal direction of the square timber, the notch groove having a depth equivalent to the thickness of the side panels 65, 66 and capable of receiving the ends of these panels.

[0083] 8A and 8B, a speaker box 70 according to a second embodiment (hereinafter referred to as "Embodiment (3)") is a sealed type speaker box having a square prism shape. Therefore, the speaker box 70 is primarily composed of a square baffle 73 and rear panel 74, semi-square cylindrical side panels 75 and 76, two rectangular prism-shaped segments 71 and 72, one tension rod 79, and a nut. In other words, while the aforementioned speaker box 60 is cylindrical, this speaker box 70 differs in that it is square prism-shaped.

[0084] Therefore, segments 71 and 72, baffle 73, unit hole 73a, rear panel 74, side panel 75, rod hole 75a, side panel 76, rod hole 76a, and tension rod 79 correspond to segments 61 and 62, baffle 63, unit hole 63a, rear panel 64, side panel 65, rod hole 65a, side panel 66, rod hole 66a, and tension rod 69, respectively, that make up the speaker box 60 described above. Therefore, a description of these will be omitted.

[0085] Like the segments 61 and 62 of embodiment (2), the segments 71 and 72 of this embodiment (3) are connected to the baffle 73 and rear panel 74, and together with the baffle 73 and rear panel 74, can correspond to a frame that surrounds at least a portion of the internal space SP of the speaker box 70, that is, a frame having four sides of a rectangular cross-sectional shape obtained by cutting the square prism shape of the speaker box 70 along its central axis.

[0086] In the second embodiment, the speaker box 60 is configured to have a cylindrical shape, while in the third embodiment, the speaker box 70 is configured to have a square prism shape. When the pressure applied by the tension rods 69, 79 narrows the gap between the opposing side panels 65, 66, 75, 76, the internal space SP of the speaker boxes 60, 70 changes so that its volume decreases, and the natural frequency of the speaker boxes 60, 70 also changes. This makes it possible to change the natural frequency of the speaker boxes 60, 70, and therefore the frequency at which standing waves occur (resonant frequency) when the speaker unit 10 vibrates at this natural frequency. It also makes it possible to change the reverberation characteristics of sound emitted from the rear surface 11 of the speaker unit 10, which reverberates off the side panels 65, 66, 75, 76.

[0087] Therefore, a speaker constructed with such speaker boxes 60, 70 and speaker unit 10 can be easily tuned to suit the installation environment by adjusting the pressure applied by the tension rods 69, 79. Since the tension rods 69, 79 consist of the tension rods 69, 79 and the nuts that screw onto them, they are not likely to be expensive. This prevents increases in cost and allows the speaker to be adapted to the installation environment.

[0088] Furthermore, the side panels 65, 66, 75, and 76 can be easily attached and detached depending on whether or not the tension rods 69 and 79 apply pressure, simplifying the replacement of the side panels 65, 66, 75, and 76. Therefore, not only can the side panels 65, 66, 75, and 76 be adapted to the installation environment, but they can also be easily replaced with panels made of materials (e.g., veneer, laminated wood, plywood, particle board, metal, hard resin, etc.) suitable for the type of music or sound source, such as classical, jazz, rock, or pop. Therefore, the reverberation characteristics of the sound emitted from the rear surface 11 of the speaker unit 10 and reflected by the side panels 65, 66, 75, and 76 in the internal space SP of the speaker box 60 and 70 can be changed by changing the materials used. This makes it easy to provide sounds that match the listener's preferences.

[0089] In the speaker box 60 of the second embodiment, the baffle 63 and rear panel 64 are formed in a circular shape, but they may also be formed in an elliptical or oval shape, for example, to form a sealed speaker box having an elliptical cylindrical or oval cylindrical shape. In this case, for example, by providing a unit hole corresponding to the unit hole 63a at an eccentric position in the elliptical or oval baffle, it is possible to ensure space for providing a rod hole in the baffle.

[0090] In addition, in the speaker box 70 of this embodiment (part 3), the baffle 73 and rear panel 74 are formed in a square shape, but for example, they may be formed in a rectangular shape to form a sealed speaker box having a rectangular prism shape. In this case, for example, by providing a unit hole corresponding to the unit hole 73a at an eccentric position in the rectangular baffle, it is possible to secure space for providing a rod hole in the baffle.

[0091] These features allow tension rods to be inserted through the speaker box in the axial direction (Y-axis direction). For example, if the rear panels 64, 74 are constructed of a wood material (such as a single board, laminated wood, plywood, or particle board) thinner than the baffles 63, 73 or a metal plate with excellent spring properties (such as a phosphor bronze plate), the pressure applied by the tension rods in the Y-axis direction narrows the gap between the baffles 63, 73 and the rear panels 64, 74. This reduces the volume of the speaker box's internal space SP, thereby changing the speaker box's natural frequency. This allows the speaker box's natural frequency to be changed, thereby changing the frequency at which standing waves occur (resonance frequency), which may occur when the speaker unit 10 vibrates at this natural frequency. Furthermore, the reverberation characteristics of the sound emitted from the rear surface 11 of the speaker unit 10 reverberate off the side panels 65, 66, 75, and 76 can be changed.

[0092] As shown in Figures 9(A) to (C), a speaker box 80 of a third other embodiment (hereinafter referred to as "Embodiment (No. 4)") is a sealed type having a regular triangular prism shape. Therefore, the speaker box 80 is mainly composed of a baffle 84 and rear panel 85 having a regular triangular shape, rectangular side panels 85, 86, and 87, three segments 81, 82, and 83 having a prismatic shape, and three tension rods 91, 92, and 93 and their nuts. Note that in Figure 9(B), the side panel 88 is represented by a two-dot chain line so that the segments 81 and 82, rear panel 85, and tension rods 91, 92, and 93, which are hidden behind the side panel 88, can be seen. Therefore, in the exploded perspective view, the side panel 88 exists in the same way as the other side panels 86 and 87.

[0093] The baffle 84 is, for example, an equilateral triangular flat plate member having an outer diameter to which the speaker unit 10 described in the above-mentioned embodiment (part 1) can be attached, and is made of a relatively thick wooden material (for example, laminated wood, plywood, particle board, etc.). The baffle 84 is formed with unit holes 84a to which the speaker unit 10 can be attached. The rear panel 85 is an equilateral triangular flat plate member facing the baffle 84, and is constructed in the same manner as the baffle 84 except that it does not have the unit holes 84a formed therein.

[0094] In the speaker box 80 of the fourth embodiment, the baffle 84 and rear panel 85 have an equilateral triangular shape, and these opposing panels 84, 85 are connected at the three vertices of the triangle by three segments 81, 82, and 83. The segments 81 to 83 have, for example, a prismatic shape (such as a square piece of material whose cross section in the thickness direction has sides of a predetermined length), and their length is set to correspond to the axial length of the speaker box 80. One end of each of the segments 81 to 83 is connected to the baffle 84, and the other end is connected to the rear panel 85.

[0095] In this way, the segments 81 to 83 are connected to the baffle 84 and rear panel 85, and are arranged together with the baffle 84 and rear panel 85 to surround the internal space SP of the speaker box 80. In other words, for the speaker box 80 which has a regular triangular prism shape, the segments 81 to 83 are configured like the sides of the regular triangular prism shape.

[0096] The side panels 86, 87, and 88 are rectangular, flat plate members that can be attached to the segments 81 to 83 so as to cover the rectangular shape formed by the two opposing sides of the baffle 84 and the rear panel 85 and the two segments. The side panels 86 to 88 are made of, for example, a wood material (such as a single board, laminated wood, plywood, or particle board) that is thinner than the baffle 84 or the rear panel 85, or a metal plate with excellent spring properties (such as a phosphor bronze plate), and have rod holes 86 a, 87 a, and 88 a formed approximately in the centers thereof. These rod holes 86 a to 88 a allow the insertion of tension rods 91, 92, and 93, and their inner diameters are set slightly larger than the shaft diameters of the tension rods 91 to 93.

[0097] In this embodiment (No. 4), for example, side panel 86 is attached to segments 81 and 82 so as to cover the rectangular frame formed by side 84α of baffle 84, side 85α of rear panel 85, and segments 81 and 82. Side panel 87 is attached to segments 82 and 83 so as to cover the rectangular frame formed by side 84β of baffle 84, side 85β of rear panel 85, and segments 82 and 83. Side panel 88 is attached to segments 81 and 83 so as to cover the rectangular frame formed by side 84γ of baffle 84, side 85γ of rear panel 85, and segments 81 and 83. Although not shown in FIG. 9 , segments 81 to 83 each have a notch groove formed along the longitudinal direction of the square timber, the notch groove having a depth equivalent to the plate thickness of side panels 86 to 88 and capable of receiving the ends of these panels.

[0098] The tension rods 91, 92, and 93 are long-shaft bolts whose axial length is longer than the perpendicular line connecting the vertices of the equilateral triangle of the speaker box 80 to the side opposite those vertices at the shortest distance. In this embodiment (No. 4), for example, one end has a countersunk head (not shown) and the other end has a male thread (not shown). The tension rods are inserted through the approximate centers of the segments 81 to 83 and the rod holes 86a to 88a in the side panels 86 to 88 facing those segments 81 to 83, respectively, and then penetrate the speaker box 80 in the radial direction. Then, they are fastened with nuts (not shown) that thread onto the male thread. Alternatively, one end of the tension rod 91 may be pre-fixed to the approximate center of the segment 81, one end of the tension rod 92 to the approximate center of the segment 82, and one end of the tension rod 93 to the approximate center of the segment 83.

[0099] As a result, when the side panels 86, 87, and 88 are compressed by the tension rods 91-93 and their nuts, they deform by being recessed inward into the speaker box 80 depending on the pressure, or when the pressure is reduced, they bulge outward, approaching (recovering) their original shape before compression. In the speaker box 80 of embodiment (4) configured in this way, when the tension rod 91 penetrating from the segment 81 to the side panel 87 is tightened, the side panel 87 deforms (warps) by being recessed toward the inside of the speaker box 80 (internal space SP). Furthermore, when the tension rod 92 penetrating from the segment 82 to the side panel 88 is tightened, the side panel 88 deforms by being recessed toward the inside of the speaker box 80. Furthermore, when the tension rod 93 penetrating from the segment 83 to the side panel 86 is tightened, the side panel 86 deforms by being recessed toward the inside of the speaker box 80. In the fourth embodiment, the side panels 86 to 88 are thinner than the baffle 84 and rear panel 85, and therefore have a greater amount of deformation (warpage).

[0100] In the fourth embodiment, the speaker box 80 is configured to have a regular triangular prism shape, and the pressure applied by the tension rods 91-93 causes the side panels 86-88 to deform, recessing toward the inside of the speaker box 80. As a result, the internal space SP changes and its volume decreases, and the natural frequency of the speaker box 80 also changes. This makes it possible to change the natural frequency of the speaker box 80, and therefore the frequency at which standing waves occur (resonance frequency) when the speaker unit 10 vibrates at this natural frequency. It also makes it possible to change the reverberation characteristics of the side panels 86-88, where sound emitted from the rear surface 11 of the speaker unit 10 reverberates.

[0101] Therefore, a speaker constructed with such a speaker box 80 and speaker unit 10 can be easily tuned to suit the installation environment by adjusting the pressure applied by the tension rods 91 to 93. Because the tension rods 91 to 93 consist of the tension rods 91 to 93 and the nuts that screw onto them, they are not likely to be expensive. This prevents increases in cost and allows the speaker to be adapted to the installation environment.

[0102] Furthermore, the side panels 86-88 can be easily attached and detached depending on whether or not the tension rods 91-93 apply pressure, simplifying the replacement of the side panels 86-88. Therefore, not only can the side panels 86-88 be adapted to the installation environment, but they can also be easily replaced with panels made of materials (e.g., veneer, laminated wood, plywood, particle board, metal, hard resin, etc.) suitable for the type of music or sound source, such as classical, jazz, rock, or pop. Therefore, the reverberation characteristics of the sound emitted from the rear surface 11 of the speaker unit 10 and reflected by the side panels 86-88 in the interior space SP of the speaker box 80 can be changed by changing the materials used. This makes it easy to provide sounds that match the listener's preferences.

[0103] In the speaker box 80 of the fourth embodiment, the baffle 84 and rear panel 85 are formed in an equilateral triangle shape, but for example, they may be formed in an elongated triangle shape such as an isosceles triangle to form a sealed speaker box having an elongated triangular prism shape. In this case, for example, by providing a unit hole corresponding to unit hole 84a at an eccentric position in the elongated triangular baffle, it is possible to ensure space for providing a rod hole in the baffle.

[0104] This allows tension rods to be inserted through the speaker box in the axial direction (Y-axis direction). For example, if the elongated triangular rear panel is constructed of a wood material (such as veneer, laminated wood, plywood, or particle board) thinner than the elongated triangular baffle or a metal plate with excellent spring properties (such as phosphor bronze), the pressure applied by the tension rod in the Y-axis direction narrows the gap between the baffle and the rear panel. This reduces the volume of the speaker box's internal space SP, thereby changing the speaker box's natural frequency. This allows the speaker box's natural frequency to be changed, thereby changing the frequency at which standing waves occur (resonance frequency) when the speaker unit 10 vibrates at this natural frequency. This also changes the reverberation characteristics of the sound emitted from the rear surface 11 of the speaker unit 10 reverberating off the side panels 86-88.

[0105] In the speaker box 20 of the above-described embodiment (part 1), pressure is applied to the pair of opposing baffles 21 and rear panels 22 by tension rods 51 and nuts 52, to the pair of opposing side panels 23, 24 by tension rods 53 and nuts 54, and to the pair of opposing top panels 25 and bottom panels 26 by tension rods 55 and nuts 56, so as to narrow the gap between each panel, but the number of tension rods that apply pressure to the pair of opposing panels is not limited to one.

[0106] For example, it may be configured so that pressure can be applied to a pair of side panels 24, 25 by two or more tension rods arranged in the up-down or front-back direction, or so that pressure can be applied to a pair of top panel 25 and bottom panel 26 by two or more tension rods arranged in the left-right or front-back direction. This allows pressure to be applied over a wide range in the surface direction, making it possible to expand the deformation range of these panels 21 to 26 and increase the variation in deformation by applying uneven pressure to each tension rod.

[0107] Furthermore, in the speaker box 60 of the second embodiment and the speaker box 70 of the third embodiment, the number of tension rods that apply pressure to the pair of opposing side panels 65, 66 or the pair of side panels 75, 76 is not limited to one. These side panels 65, 66, 75, 76 may be configured to apply pressure using two or more tension rods arranged in the vertical or front-to-rear direction.

[0108] Furthermore, in the speaker box 80 of the fourth embodiment, the number of tension rods that apply pressure to the side panels 86, 87, and 88 is not limited to one each. Each of the side panels 86 to 88 may be configured to apply pressure using two or more tension rods arranged in the up-down or front-to-back directions.

[0109] This allows the speaker boxes 60, 70, and 80 to be pressurized over a wide range in the surface direction, making it possible to expand the deformation range of these panels 65, 66, 75, 76, 86 to 88 and increase the variation in deformation by applying uneven pressure to each tension rod.

[0110] Furthermore, in the speaker boxes 20, 60, 70, 80 of the above-mentioned embodiments (No. 1) to (No. 4), an example has been given in which the panels 21 to 26 including the baffle 21 and the side panels 65, 66, 75, 76, 86 to 88 are pressurized from the outside by the tension rod 51 etc. or the tension rods 69, 79, 91 to 93 and their nuts, but the speaker box of the present invention is not limited to this, and as long as it is possible to reduce or increase the volume of the internal space that houses the rear side of the speaker unit, it is also possible to reduce or increase the volume of the internal space by applying an attractive force from the inside of these panels 21 to 26 or side panels 65, 66 etc.

[0111] For example, both ends of a rod-shaped telescopic mechanism whose amount of expansion and contraction can be controlled externally (a mechanism that extends when rotated clockwise and contracts when rotated counterclockwise by inserting a screwdriver or the like externally and operating it) are connected to the inside of a pair of opposing side panels 24, 25, etc. (in the case of embodiments (1) to (3)) or to the inside of a pair of opposing segment 81 and side panel 87, etc. (in the case of embodiment (4)). This allows the pair of side panels 24, 25, etc. or the side panel 87, etc., to be deformed so that they are recessed inward, thereby decreasing or increasing the volume of the internal space SP of the speaker box 20, 60, 70, 80. Therefore, even if such a telescopic mechanism is provided within the internal space SP of the speaker box 20, 60, 70, 80, tuning to suit the installation environment is easily possible. Furthermore, such a telescopic mechanism can generally be realized using mechanical components, and therefore is not costly. This prevents costs from increasing and allows the speaker box to adapt to the installation environment.

[0112] 1 to 4, the inventors measured the frequency characteristics of the sound pressure level of the sound output from the speaker 2 in order to confirm the change in the natural frequency when pressure is applied to the side panels 23, 24, etc. by the tension rods 53, 55. Note that in this measurement, four different types of panels (veneer, aluminum plate, acrylic plate, and MDF (Medium Density Fiberboard)) were used as the side panels 23, 24, top panel 25, and bottom panel 26, and changes in the reverberation characteristics due to differences in material were also confirmed.

[0113] First, the measurement system used in this measurement will be described with reference to Fig. 10. As shown in Fig. 10, measurement system 100 is composed of low-frequency oscillator 101 and amplifier 103, which output a low-frequency signal of 20 Hz to 20 kHz to speaker 2 placed on mounting stand S to activate speaker unit 10, and microphone 105, amplifier 106, low-pass filter 107, and level meter 108, which collect the sound emitted by speaker 2 diagonally above it and measure its level. Note that this measurement was carried out in an anechoic chamber (sound transmission loss of 40 dB or more, cutoff frequency of sound absorber 200 Hz, background noise level 20 dB or less).

[0114] The speaker unit 10 constituting the speaker 2 used in this measurement system 100 is a coaxial 2-way full-range unit (model number 409-8E) manufactured by Altec Lansing Technologies, USA, and its specifications are as follows: Unit: low-frequency aperture 20 cm, high-frequency aperture 5 cm, crossover frequency 2.5 kHz; playback frequency range: 50 Hz to 14 kHz, minimum resonance frequency 90 Hz; efficiency: 98 dB; impedance: 8 Ω; maximum input: 64 W (continuous); external dimensions: diameter 21 cm, thickness 8 cm, weight: 1.3 kg.

[0115] The external dimensions of the speaker box 20, baffle 21, etc. are as follows: Speaker box 20 (including frame 30): Width 36 cm x Height 40 cm x Depth 40 cm Baffle 21 and rear panel 22: Width 25.6 cm x Height 32.8 cm x Thickness 0.4 cm Unit hole 21a formed at the center of baffle 21: Opening diameter 19.5 cm Side panels 23, 24: Width 32.8 cm x Height 32.8 cm Top panel 25 and bottom panel 26: Width 28.8 cm x Height 32.8 cm

[0116] The frame 30 was made of wood, and the baffle 21 and rear panel 22 were made of MDF. For these measurements, four types of panels with different materials and thicknesses (veneer plywood (5.5 mm thick), aluminum plate (1.0 mm thick), acrylic plate (2.0 mm thick), and MDF (4.0 mm thick)) were prepared as the side panels 23 and 24, the top panel 25, and the bottom panel 26. These panels were secured to the frame 30 by applying wide adhesive tape (e.g., packing tape) to all sides of the panels 23 to 26, covering both the panels and the frame 30.

[0117] The tension rods 53, 55 were of the M6 ​​type (metric thread with a thread pitch of 1 mm and a shaft diameter of 6 mm) and had a shaft length long enough to extend between the side panels 23 and 24 or between the top panel 25 and the bottom panel 26. A cap nut was threaded onto one end of the tension rods 53, 55, and a wing nut was threaded onto the other end, and these nuts were abutted against the side panels 23, 24, the top panel 25, or the bottom panel 26 via flat washers with an outer diameter of 22 mm and a thickness of 1 mm.

[0118] For this reason, pressure is applied by rotating the wing nuts on the other ends of tension rods 53, 55 in the screw-tightening direction, and the separation distance (between the panels) between side panels 23 and 24 or top panel 25 and bottom panel 26 narrows in response to the applied pressure, bending them toward the inside of speaker box 20. This measurement was performed in three patterns: a state where no pressure is applied by tension rods 53, 55 (unpressurized state), a state where the wing nuts are turned two times in the screw-tightening direction and pressurized by 2 mm of the screw pitch (2 mm pressurized state), and a state where the wing nuts are turned five times in the screw-tightening direction and pressurized by 5 mm of the screw pitch (5 mm pressurized state).

[0119] The low-frequency oscillator 101 utilizes the function of a sine wave oscillator (output frequency 5 Hz to 159.9 kHz) provided in an audio analyzer (model number VP-7721A) manufactured by Matsushita Communication Industrial Co., Ltd. The amplifier 103 is a Lepy brand power amplifier (model number LP-V3S) manufactured by STRIVEHUGTOSUCCESS, which is an audio amplifier capable of amplifying the low-frequency sine wave signal output from the low-frequency oscillator 101 to an output power of 10 W or more (maximum output 25 W + 25 W (2 channels)) sufficient to drive the speaker unit 10. The mounting stand S on which the speaker box 20 is placed has a height Da set to 77.5 cm from the floor F.

[0120] The microphone 105 is a Superlux brand omnidirectional measurement condenser microphone (model number EMC999) manufactured by Global Spec Corporation of Taiwan, with a frequency response of 20 Hz to 20 kHz and a sensitivity of -37 dBV / Pa (14 mV). In this measurement, the microphone 105 was installed at a distance Db of 48 cm from the baffle 21 of the speaker 2 and at a height Dc of 175 cm from the floor F. In other words, sound was picked up by the microphone 105 diagonally above the speaker 2.

[0121] The amplifier 106 is a TOPINCN brand audio amplifier (model number M-20) and functions as a preamplifier for the microphone 105 in the measurement system 100. The gain of this amplifier 106 was adjusted so that the needle of the level meter 108 indicated 0 dB when the speaker unit 10 was operated at a frequency of 440 Hz and 3.3 Wrms. The low-pass filter 107 has a cutoff frequency of 100 kHz and was provided for the purpose of removing power supply noise generated by a switching power supply (not shown) that drives the amplifier 106.

[0122] The level meter 108 is an AC voltmeter capable of measuring the sound pressure (sound pressure level) of the sound output from the speaker 2 as an effective value of AC voltage, and utilizes a function provided in the audio analyzer (model number VP-7721A) mentioned above. 0 dB on this level meter 108 is 1 Vrms, which corresponds to the AC voltage level (effective value of AC voltage) obtained when the speaker unit 10 in the unpressurized speaker box 20 is operated at a frequency of 440 Hz and 3.3 Wrms and the sound picked up by the microphone 105 is amplified by the amplifier 106.

[0123] The inventors of the present application used this measurement system 100 to confirm the changes in natural frequency in the three states (unpressured, 2 mm pressurized, and 5 mm pressurized) for the side panels 23, 24, top panel 25, and bottom panel 26 when they were made of plywood ( FIG. 11 ), aluminum ( FIG. 12 ), acrylic ( FIG. 13 ), and MDF ( FIG. 14 ). Note that plywood corresponds to the aforementioned plywood. Aluminum corresponds to the aforementioned metal. Acrylic corresponds to the aforementioned hard resin. MDF, like the aforementioned particle board, is a type of wood board and is also known as medium-density fiberboard.

[0124] 11 to 14 are characteristic diagrams showing examples of frequency characteristics of the sound pressure level of the sound output from speaker 2, with the vertical axis (linear axis) representing the value (unit: dB) of level meter 108 and the horizontal axis (logarithmic axis) representing the frequency (unit: Hz) of the low-frequency sine wave signal output from low-frequency oscillator 101. In these diagrams, the solid line represents the frequency characteristics of the sound pressure level of the sound output from speaker 2 in the no-pressure state, the dashed line represents the frequency characteristics in the 2 mm pressurized state, and the dashed dotted line represents the frequency characteristics in the 5 mm pressurized state.

[0125] Note that Figure 15 shows the characteristic curves (solid lines) in the unpressurized state shown in Figures 11 to 14 on the same graph, thereby confirming the changes in the frequency characteristics of the sound pressure level of the sound due to differences in the materials of panels 23 to 26 (solid line: plywood, dashed line: aluminum plate, one-dot chain line: acrylic plate, two-dot chain line: MDF).

[0126] First, as shown in Figures 11 to 14, it was confirmed that, regardless of the material of the panels 23 to 26, by rotating the wing nuts of the tension rods 53, 55 in the screw-tightening direction, the frequency characteristics of the sound pressure level of the sound output from the speaker 2 changed compared to the solid line in the no-pressure state (dashed line in the 2 mm pressurized state, dashed line in the 5 mm pressurized state).

[0127] In particular, when panels 23 to 26 are made of plywood, the maximum sound pressure level is around 600 Hz in the unpressurized state, but changes to around 350 Hz with a 2 mm pressure and to around 120 Hz with a 5 mm pressure (see Figure 11). Also, when panels 23 to 26 are made of aluminum plate, the maximum sound pressure level is around 170 Hz in the unpressurized state, but changes to around 150 Hz with a 2 mm pressure and to around 220 Hz with a 5 mm pressure (see Figure 12). These are thought to indicate changes in the natural frequency of speaker box 20.

[0128] Also, when panels 23-26 are made of acrylic plates, the change in sound pressure level due to the pressurized state is small, but it can be seen that the change appears to be shifted along the frequency axis (see Figure 13). Furthermore, when panels 23-26 are made of MDF, it can be seen that the change in sound pressure level is greater in the mid-range (200 Hz to 2 kHz) than in the low-range (20 to 200 Hz), and in the high-range (2 kHz to 20 kHz) than in the mid-range (200 Hz to 2 kHz). These are also thought to be due to changes in the natural frequency of speaker box 20.

[0129] Furthermore, as shown in Figure 15, when the materials of panels 23-26 are different, the frequency characteristics of the sound pressure level vary significantly depending on the material. For example, compared to plywood (solid line), aluminum (dashed line), acrylic (dotted line), and MDF (dotted line) all have higher sound pressure levels between approximately 70 Hz and 350 Hz, while aluminum (dashed line) and MDF (dotted line) have higher sound pressure levels even above 7 kHz. In contrast, acrylic (dotted line) has higher sound pressure levels between approximately 70 Hz and 1 kHz compared to plywood (solid line), but lower sound pressure levels below 70 Hz and above 1.5 kHz. This change in sound pressure level due to the different materials of panels 23-26 is thought to be due to changes in the reverberation characteristics within speaker box 20.

[0130] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications or variations of the above-described specific examples. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives alone has technical utility. Note that the description in parentheses in the [Explanation of Symbols] column may clearly indicate the correspondence between the terms used in the above-described embodiments and the terms described in the claims.

[0131] DESCRIPTION OF SYMBOLS 2...Speaker 10...Speaker unit 11...Rear surface 20...Speaker box 21...Baffle (front panel) 21a...Unit hole 21b, 22a to 26a...Rod holes 22...Rear panel (rear panel) 23, 24...Side panels (side panels) 25, 25w to 25z...Top panel (side panels) 26...Bottom panel (side panel) 27 to 29...Recess 30...Frame (frame body) 31 to 42...Segments, segments (frame body) 31a to 42b...Notched grooves (groove portions) 51, 53, 55...Tension rods (variable pressure members) 52, 54, 56...Nuts (variable pressure members) 57...Wood screws 60, 70, 80...Speaker box 61, 62, 71, 72, 81 to 83...Segments, segments (frame body) DESCRIPTION OF SYMBOLS 63, 73, 84... Baffle (front plate, frame) 63a, 73a, 84a... Unit hole 64, 74, 85... Rear panel (rear plate, frame) 65, 66, 75, 76, 86 to 88... Side panels (side panels) 65a, 66a, 75a, 76a, 86a to 88a... Rod holes 69, 79, 91, 92, 93... Tension rod (variable pressure member) 100... Measurement system 101... Low frequency oscillator 103, 106... Amplifier 105... Microphone 107... Low pass filter 108... Level meter Da, Dc... Height distance Db... Separation distance F... Floor surface S... Placement base SP... Internal space

Claims

1. A speaker box having an internal space capable of accommodating the rear side of a speaker unit, comprising: a frame surrounding at least a part of the internal space; a front plate on which the speaker unit is attached and which is provided at the front of the frame; a rear plate provided at the rear of the frame opposite the front plate; a side plate provided on a side of the frame; another side plate provided on the other side of the frame opposite the one side plate; and a variable pressure member that can apply pressure or attractive force (hereinafter referred to as "pressure, etc.") to a set of opposing plates in a direction narrowing the distance between the plates and can change the pressure, etc., wherein the set of plates is the one side plate and the other side plate, and / or the front plate and the rear plate.

2. A speaker box as described in claim 1, characterized in that the frame has a groove that can surround the side of at least one of the front plate, the rear plate, the one side plate and the other side plate or abut the inner surface of the periphery and can receive part or all of the periphery, and the variable pressure member can attach the at least one plate to the frame by applying pressure, etc. to the at least one plate and the opposing plate, and can remove the at least one plate from the frame by not applying pressure, etc.

3. A speaker box as described in claim 1 or 2, characterized in that one or more of the front panel, the rear panel, the one side panel and the other side panel are made of a material that is partially or entirely different from the remaining panels.

4. A speaker box as described in claim 1 or 2, characterized in that one or more of the front panel, the rear panel, the one side panel and the other side panel have a thickness that is different in part or in whole from the remaining other panels.

Images