US20090211840A1

US20090211840A1 - Loudspeaker Enclosure

Info

Publication number: US20090211840A1
Application number: US12/036,236
Authority: US
Inventors: Peigen Jiang
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-02-23
Filing date: 2008-02-23
Publication date: 2009-08-27

Abstract

A loudspeaker enclosure is disclosed which comprises an inner cabinet having a front baffle for mounting one or more loudspeaker drivers, the inner cabinet being a self-sustaining enclosure, and an outer cabinet covering at least a half of the inner cabinet surface area but exposing the one or more loudspeaker drivers, the outer cabinet keeping a gap from the inner cabinet.

Description

BACKGROUND

The present invention relates generally to loudspeakers, and, more particularly, to a loudspeaker enclosure structure.
One goal for better sound reproduction by loudspeakers employing dynamic drivers is to make the loudspeaker enclosure as inert as possible. Therefore, loudspeaker enclosures are typically made out of rigid materials such as median-density-fiberboard (MDF) or aluminum. The loudspeaker enclosures are made very thick as well. As a result, some high-end loudspeakers weight as much as 700 pounds each.
Another goal for better sound reproduction by such loudspeakers is to dampen the sound inside the loudspeaker enclosure as much as possible. However, rigid materials such as MDF or aluminum are very poor damping materials. In order to kills off the unwanted sound inside the loudspeaker enclosures, some are made to have odd shaped or curved enclosures, and are lined with damping materials inside the enclosure. Such solutions make loudspeaker production more complicated and certainly add to the cost.
A U.S. Pat. No. 6,719,092 discloses a lightweight loudspeaker enclosure with sandwiched panels. While the weight can be reduced, but such sandwiched panel structure is complicated to manufacture, does not have adequate mass to remain inert in bass sound impact.
As such, what is desired is loudspeaker enclosure that has good internal damping as well as good external inert characteristics.

SUMMARY

The present invention discloses a loudspeaker enclosure which comprises an inner cabinet having a front baffle for mounting one or more loudspeaker drivers, the inner cabinet being a self-sustaining enclosure, and an outer cabinet covering at least a half of the inner cabinet surface area but exposing the one or more loudspeaker drivers, the outer cabinet keeping a gap from the inner cabinet.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a loudspeaker having separated inner and outer cabinets according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view of the loudspeaker of FIG. 1.

The drawings accompanying and forming part of this specification are included to depict certain aspects of the invention. A clearer conception of the invention, and of the components and operation of systems provided with the invention, will become more readily apparent by referring to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings, wherein like reference numbers (if they occur in more than one view) designate the same elements. The invention may be better understood by reference to one or more of these drawings in combination with the description presented herein. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale.

Description

The following will provide a detailed description of a loudspeaker enclosure that has separated inner and outer cabinets for good internal damping as well as good external inert characteristics.
FIG. 1 is a perspective view of a loudspeaker 100 having separated inner and outer cabinets according to one embodiment of the present invention. The loudspeaker 100 comprises an outer cabinet 110, an inner cabinet 130 and a gap 120 between the outer cabinet 110 and the inner cabinet 130. Two exemplary drivers, a tweeter 103 and a woofer 106, are mounted on a front baffle of the inner cabinet 130. The inner cabinet 130 is an entirely enclosed cabinet that prevents the sound produced from the back of the drivers 103 and 106 from escaping out of the loudspeaker 100. However, the inner cabinet 130 will inevitably vibrate and produce a sound under the acoustic energy of the drivers 103 and 106. Then the outer cabinet 110 seals off the sound produced by the inner cabinet 130.
Referring again to FIG. 1, the exemplary loudspeaker 100 has a box-like shape. The outer cabinet 110 comprises panels on five sides with only the front baffle of the inner cabinet 130 being exposed, so that sound can be radiated from the front of the drivers 103 and 106. The gap 120 between the outer cabinet 110 and the inner cabinet 130 prevents the vibration of the inner cabinet 130 from reaching the outer cabinet 110. Therefore, the outer cabinet 110 is a very quiet one without requiring massive weight. Since the outer cabinet 110 covers five sides of the loudspeaker 100, the inertness of the enclosure thereof is greatly improved.
FIG. 2 is a cross-sectional view of the loudspeaker 100 of FIG. 1. The outer cabinet 110 surrounds the inner cabinet 130 on all sizes except the front baffle where the woofer 106 is mounted. The gap 120 separates the outer cabinet 100 from the inner cabinet 130. A plurality of spacers 225 are placed in regular intervals in the gap 120 for maintaining the same. In order to reduce couplings between the inner cabinet 130 and the outer cabinet 110, the plurality of spacers 225 may be made of a vibration damping material such as rubber. In order to bond the outer cabinet 110 and the inner cabinet 130 together, screws may be used (not shown) either from inside screwing toward outer cabinet 110, or from outside screwing toward the inner cabinet 130. Since the function of these screws is only to prevent the inner cabinet 130 from sliding out from the only opening side of the outer cabinet 110, there is no need for many of such screws. For instance, one screw on each of the five sides can hold the inner cabinet 130 onto the outer cabinet 110. Fewer screws reduce the coupling between the inner cabinet 130 and the outer cabinet 110. In this case, the outer cabinet 110 and the inner cabinet 130 can be independently assembled, and then the inner cabinet 130 can slide in the outer cabinet 110. Apparently, the screws can be replaced with other fixtures such as pins.
A skilled artisan may also realize that there are many other ways to hold the inner cabinet 130 onto the outer cabinet 110, such as making the opening of the outer cabinet 110 slightly smaller than the inner cabinet 130. In this case, the outer cabinet 110 has to be assembled after the inner cabinet 130 being placed inside. In this case, fastening devices may be spared, but at some point the outer cabinet 110 will make contact with the inner cabinet 130. But as long as the contact does not substantially relay the vibration from the inner cabinet 130 to the outer cabinet 110, the isolation between the inner cabinet 130 and the outer cabinet 110 is achieved.
Beside sealing the sound, it is also desirable for the inner cabinet 130 to dampen the sound, therefore, some low density materials, such as low-density-fiberboard (LDF) or plywood, can be used for constructing the inner cabinet 130 except the front baffle where the drivers 103 and 106 are to be mounted. The front baffle of the inner cabinet 130 should be made as rigid as possible.
Since the acoustic purpose of the outer cabinet 110 is to seal off the sound, the outer cabinet 110 should be made of rigid materials, such as MDF or aluminum.
Since both the outer cabinet 110 and inner cabinet 130 need to hold up on their own, the panels thereof should be strong enough and thick enough. In case they are made of fiberboards, the thickness of the fiberboards in general should be thicker than one half inch.
In case there is a large area of the front baffle not being occupied by sound producing drivers, the outer cabinet 110 can be extended to cover that area as well, without making contact with the inner cabinet 130. Screws or other fastening fixtures may be used to bond this part of the outer cabinet 110 to the inner cabinet 130.
Referring again to FIG. 2, the gap 120 may be filled with some sort of sound proofing material to further improve the inertness of the loudspeaker 100. Lose sand or fiberglass can be such filling material. Then the inlet of the gap 120 should be sealed, ideally, also by a sound damping material, such as silicone.
For a ported enclosure design, a port opening has to be made on the inner cabinet 130 either on the front baffle or another side of the inner cabinet 130, otherwise the inner cabinet 130 is an enclosed box when the drivers are installed. The inner cabinet 130 is also a self-sustaining box. In fact, the inner cabinet 130 is very much like a conventional single-layered loudspeaker. Since the outer cabinet 110 essentially has no contact with the inner cabinet 130, the outer cabinet 110 has to be self-sustaining and structurally sound as well. To be self-sustaining and have proper structural strength, the side walls of both the outer cabinet 110 and inner cabinet 130 should have enough thickness, and ideally be thicker than one half inches.
The above illustration provides many different embodiments or embodiments for implementing different features of the invention. Specific embodiments of components and processes are described to help clarify the invention. These are, of course, merely embodiments and are not intended to limit the invention from that described in the claims.
Although the invention is illustrated and described herein as embodied in one or more specific examples, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention, as set forth in the following claims.

Claims

1. A loudspeaker enclosure comprising:

an inner cabinet having a front baffle for mounting one or more loudspeaker drivers, the inner cabinet being a self-sustaining enclosure; and

an outer cabinet covering at least a half of the inner cabinet surface area but exposing the one or more loudspeaker drivers, the outer cabinet being self-sustaining and keeping a gap from the inner cabinet.

2. The loudspeaker enclosure of claim 1, wherein the gap between the inner and outer cabinet is less than a half inch distance.

3. The loudspeaker enclosure of claim 1, wherein the side walls of both the inner and outer cabinets are at least one half inch thick.

4. The loudspeaker enclosure of claim 1, wherein both the inner and outer cabinets are box-shaped, and the inner cabinet has panels in all six sides, while the outer cabinet has panels on five sides leaving the loudspeaker driver mounting side of the inner cabinet exposed.

5. The loudspeaker enclosure of claim 4 further comprising a panel partially covering the loudspeaker driver mounting side of the inner cabinet but still exposing the one or more loudspeaker drivers.

6. The loudspeaker enclosure of claim 1 further comprising one or more spacers in the gap between the inner and outer cabinet, the spacers being made of a vibration damping material.

7. The loudspeaker enclosure of claim 1 further comprising a filling material in the gap between the inner and outer cabinet, the filling material being a sound proofing material.

8. The loudspeaker enclosure of claim 1 further comprising one or more fastening devices holding the inner and outer cabinets together.

9. The loudspeaker enclosure of claim 1, wherein the side walls of the inner cabinet are made of a low-density-fiberboard, while the side walls of the outer cabinet are made of a medium-density-fiberboard.

10. A loudspeaker enclosure comprising:

an inner cabinet having a front baffle for mounting one or more loudspeaker drivers, the inner cabinet being a self-sustaining enclosure with side walls at least one half inch thick; and

an outer cabinet covering at least a half of the inner cabinet surface area but exposing the one or more loudspeaker drivers, the outer cabinet being self-sustaining with side walls at least one half inch thick and keeping a gap from the inner cabinet.

11. The loudspeaker enclosure of claim 10, wherein the gap between the inner and outer cabinet are less than a half inch distance.

12. The loudspeaker enclosure of claim 10, wherein both the inner and outer cabinets are box-shaped, and the inner cabinet has panels in all six sides, while the outer cabinet has panels on five sides leaving the loudspeaker driver mounting side of the inner cabinet exposed.

13. The loudspeaker enclosure of claim 12 further comprising a panel partially covering the loudspeaker driver mounting side of the inner cabinet but still exposing the one or more loudspeaker drivers.

14. The loudspeaker enclosure of claim 10 further comprising one or more spacers in the gap between the inner and outer cabinet, the spacers being made of a vibration damping material.

15. The loudspeaker enclosure of claim 10 further comprising a filling material between the inner and outer cabinet, the filling material being a sound proofing material.

16. The loudspeaker enclosure of claim 10 further comprising one or more fastening devices holding the inner and outer cabinets together.

17. The loudspeaker enclosure of claim 10, wherein the side walls of the inner cabinet are made of a low-density-fiberboard, while the side walls of the outer cabinet are made of a high-density-fiberboard.

18. A loudspeaker enclosure comprising:

an outer cabinet covering at least a half of the inner cabinet surface area but exposing the one or more loudspeaker drivers, the outer cabinet being self-sustaining with side walls at least one half inch thick and keeping a gap from the inner cabinet,

wherein gap between the inner and outer cabinet is less than a half inch distance.

19. The loudspeaker enclosure of claim 18, wherein both the inner and outer cabinets are box-shaped, and the inner cabinet has panels in all six sides, while the outer cabinet has panels on five sides leaving the loudspeaker driver mounting side of the inner cabinet exposed.

20. The loudspeaker enclosure of claim 18 further comprising:

one or more spacers between the inner and outer cabinet, the spacers being made of a vibration damping material; and

a filling material in the gap between the inner and outer cabinet, the filling material being a sound proofing material.