Dynamic acoustic waveguide

Abstract

A loudspeaker and a method of operation which allow for the production and emphasis of extremely low bass tones. The loudspeaker generally is formed from a loudspeaker driver cone of conventional type which is placed in a very small enclosure with two waveguides attached thereto. A smaller balance waveguide is positioned forward of the face of the cone and a larger tuning waveguide is positioned to the side of the cone. The cross-sectional area of the aperture connections of both waveguides to the enclosure are small compared to the cross-sectional area of the loudspeaker driver cone.

Claims

1. A loudspeaker comprising: an enclosure having a back side and an opposing front side, said enclosure enclosing a loudspeaker driver cone having a cross-sectional area at a forward face, said loudspeaker driver cone being disposed in said enclosure such that said cross-sectional area is generally flush with said front side; a tuning waveguide coupled to said enclosure at a position lateral to the loudspeaker driver cone, said tuning waveguide extending from said enclosure in a direction generally parallel to the plane of said cross-sectional area; and a balance waveguide coupled to said front side of said enclosure at said forward face of said loudspeaker driver cone generally coaxially with said cross-sectional area; wherein said tuning waveguide has a greater volume than said balance waveguide which in turn has a greater volume than said enclosure.

2. The loudspeaker of claim 1 wherein said tuning waveguide includes at least 2 times the volume of air of said balance waveguide.

3. The loudspeaker of claim 1 wherein said tuning waveguide includes at least 10 times the volume of air of said balance waveguide.

4. The loudspeaker of claim 1 wherein said volume of air in said tuning waveguide is at least 10 times the volume of air in said enclosure.

5. The loudspeaker of claim 1 wherein said volume of air in said balance waveguide is at least 2.5 times the volume of air in said enclosure.

6. The loudspeaker of claim 1 wherein said coupling of said tuning waveguide to said enclosure has a cross-sectional area generally the same as said cross-sectional area of said coupling of said balance waveguide to said enclosure.

7. The loudspeaker of claim 1 wherein said cross-sectional area of said coupling of said balance waveguide to said enclosure is less than 75% of said cross-sectional area of said forward face of said driver cone.

8. The loudspeaker of claim 5 wherein said cross-sectional area of said coupling of said balance waveguide to said enclosure is less than 50% of said cross-sectional area of said forward face of said driver cone.

9. The loudspeaker of claim 6 wherein said cross-sectional area of said coupling of said balance waveguide to said enclosure is less than 25% of said cross-sectional area of said forward face of said driver cone.

10. The loudspeaker of claim 1 wherein said cross-sectional area of said coupling of said balance waveguide to said enclosure is between 25% and 50%, inclusive, of said cross-sectional area of said forward face of said driver cone.

11. A method of producing a sound wave of less than 60 Hz, the method comprising: providing: an enclosure having a back side and an opposing front side, said enclosure enclosing a loudspeaker driver cone having a cross-sectional area at a forward face, said loudspeaker driver cone being disposed in said enclosure such that said cross-sectional area is disposed concentrically with said opening and is generally flush with said front side; a tuning waveguide coupled to said enclosure at a position lateral to said loudspeaker driver cone by an aperture having a cross-sectional area less than said cross-sectional area of said forward face, said tuning waveguide extending from said enclosure in a direction generally parallel to the plane of said cross-sectional area; and a balance waveguide coupled to said enclosure at said forward face of said loudspeaker driver cone generally coaxially with said cross-sectional area; wherein said tuning waveguide has a greater volume than said balance waveguide which in turn has a greater volume than said enclosure; driving said driver cone to produce a sound wave at said forward face; directing at least a portion of said sound wave into both said tuning waveguide and said balance waveguide in a manner that said sound wave upon exiting said tuning waveguide and said balance waveguide is less than 60 Hz.

12. The method of claim 11 wherein said sound wave upon exiting said tuning waveguide and said balance waveguide is less than 40 Hz.

13. The method of claim 11 wherein said sound wave upon exiting said tuning waveguide and said balance waveguide is less than 20 Hz.

14. The method of claim 11 wherein said sound wave upon exiting said tuning waveguide and said balance waveguide is less than 10 Hz.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a 2-dimensional concept drawing for the purpose of explaining a theory of operation of an embodiment of a dynamic acoustic waveguide.

(2) FIG. 2 shows a 3-dimensional exploded drawing of an embodiment of a loudspeaker utilizing a dynamic acoustic waveguide of the present invention.

(3) FIG. 3 shows a top view of the upper stack of the loudspeaker of FIG. 2.

(4) FIG. 4 shows a bottom view of the lower stack and cover of the loudspeaker of FIG. 2.

(5) FIG. 5 shows the upper stack of FIG. 3 connected to the lower stack of FIG. 4.

(6) FIG. 6 shows the embodiment of FIG. 5 from an alternative angle.

(7) FIG. 7 shows an embodiment of an upper stack of a loudspeaker which includes rounded guide pieces in the waveguides.

(8) FIG. 8 shows an embodiment of a loudspeaker in the trunk of a vehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

(9) Using the principles of resonance and a special method of acoustic coupling a dynamic acoustic waveguide of the present disclosure greatly improves the low end response and efficiency of acoustic drivers. As discussed in more detail in the FIGS, an embodiment of a dynamic acoustic waveguide will generally comprise a driver enclosure of much smaller proportions than what is considered to be standard, an overriding vent or port that is much larger in volume than the drivers enclosure, and a shorter vent or port that acts as both a low pass filter and to provide equilibrium to the loads on the front and rear of the drivers cone. Both vents or ports generally have a cross-sectional area that is markedly smaller than that of the driver.

(10) FIG. 1 provides a general concept drawing of an embodiment of an acoustic waveguide to provide amplified low tones. FIG. 1 shows a loudspeaker driver cone (1) (generally from between 10 to 20 in diameter and intended to produce bass tones but this is by no means required) of generally conventional construction and of a type well known to those of ordinary skill in the art in a small enclosure (20) with an attached large port or vent that from this point shall be referred to as the tuning waveguide (8) and an attached smaller port or vent that from this point shall be referred to as the balance waveguide (7).

(11) The balance waveguide (7), in an embodiment, will preferably have a length of 50%, 33%, 25%, or less the length of the tuning waveguide (8), depending on embodiment, however, this is by no means required. Similarly, the volume of air in the tuning waveguide (8) will generally be significantly greater than that of the balance waveguide (7). In an embodiment, this will be a volume around 2 times, 4 times, 10 times, or more than that of the balance waveguide (7). However, in alternative embodiments, this is by no means required. Specific values for both relative volumes and lengths would be selected by one of ordinary skill in the art within these ranges based on the particular tones and ranges the loudspeaker is intended to operate within and reproduce.

(12) The tuning waveguide (8) having the largest volume and therefore the largest mass air movement capability is considered dominant and generally has the greatest impact on the dynamic range of the system. The enclosure (20) is also extremely confined and in the depicted embodiment, is only as large as is necessary to enclose the cone of the driver and includes an air volume less than that of either the tuning waveguide (8) or balance waveguide (7). As shown in the FIGS, the enclosure (20) is purposefully rendered even smaller by positioning the magnet of the driver (1) outside the volume of the enclosure (20). This allows for the enclosure to be of general size of a parallelepiped having two dimensions close to or equal to the diameter of the forward face of the cone (1) and a third dimension which is less than the depth of the cone (1). In an embodiment, the volume of empty an in the enclosure (20) (the volume of air not taken up by the cone (1) itself and associated electronics attached thereto) is significantly less than the volume of air in either waveguide (7) or (8). In an embodiment, the volume of the empty air in enclosure (20) is about 1/10 of the volume of the tuning waveguide (8) or less. In yet another embodiment, the volume of the balance waveguide (7) is at least 2.5 times that of the enclosure (20). To reduce the volume of the air in a bigger formed enclosure (20), the volume of the enclosure (20) may be at least partially occupied by baffling or other material.

(13) Further, the tuning waveguide (8) is connected to the side of the driver cone (1) and is not directly behind the driver (1). Instead, the rear of the driver cone (1) is actually positioned outside the enclosure (20). The relationship between the tuning waveguide (8) and the enclosure (20) is such that the enclosure (20) becomes secondary in response to driver output and that an intended acoustic mismatch between them causes an exaggerated quarter wavelength resonance from the tuning waveguide (8). Again the volume of the tuning waveguide (8) is about 10 times or more that of the enclosure (20) in an embodiment, but that is by no means required.

(14) As should be apparent, the balance wave guide (7) in the depicted embodiment of FIG. 1 is positioned in front of the transducer or driver (1) while the larger mama waveguide (8) is positioned to the side of the driver (1). Further, both the balance waveguide (7) and the tuning cross-sectional area substantially smaller than that of the driver (1) meaning the apertures (11) and (12) are much smaller than the cross-sectional area of the forward face of the cone is generally preferred that the cross-sectional area of both the aperture (11) and the aperture (12) be similar or the same.

(15) Depending on embodiment, the aperture (11) may have a cross-sectional area of less than 75% of that of the cross-sectional area of the forward face of the driver (1). In alternative embodiments, the aperture (11) may have a cross-sectional area less than 50%, less than 25%, or between 25% and 50%, inclusive, of the cross-sectional area of the driver (1) forward face. The remaining area of the forward, face of the driver (1) is positioned against an acoustical baffle forming a portion of the acoustic guide and a base of the enclosure (20).

(16) The relatively smaller enclosure (20) volume may attribute to driver accuracy. The intended mismatch between the tuning waveguide (8) and driver enclosure (20) volume provides an efficient method of coupling between the driver (1) and tuning waveguide (8). This mismatched coupling is the result of the tuning waveguide's (8) mass air movement overriding that of the enclosure (20). The tuning waveguide's (8) dominance coupled with the small enclosure's (20) volume creates an extreme non-compliance that allows direct and efficient communication between the driver (1) and the tuning waveguide (8). The balance waveguide (7) provides equilibrium between the loads on the front and rear of the driver cone (1) improving overall efficiency. The balance waveguide (7) being shorter in length than the tuning waveguide (8) further acts as a low pass filter.

(17) FIG. 2 shows an exploded 3-dimensional drawing of an embodiment of an acoustic waveguide utilizing the principles of FIG. 1. In FIG. 2, the waveguide is in the form of a generally rectilinear cabinet (30). The cabinet (30) could be constructed of a wide variety of materials including; particle board, Medium Density Fiberboard (MDF), plywood, fiberglass, or any other suitable material. In an embodiment, the cabinet (30) will be constructed of an acoustic metamaterial such as, but not limited to those, discussed in Song et al. Emission Enhancement of Sound Emitters using an Acoustic Metamaterial Cavity Scientific Reports (3 Mar. 2014)available at www.nature.com/srep/2014/140303/srep04165/full/srep04165.html, the entire disclosure of which is herein incorporated by reference. The cabinet is generally constructed as two stacks which are arranged to be positioned on top of each other.

(18) The driver (1) is attached to the main body's upper stack (2). The main body's upper stack (2) is attached to the main body's lower stack cover (6) as is best shown in FIG. 5. The lower cover is then attached to the lower stack (3). The lower stack cover (6) encloses the lower stacks (3) portion of the tuning waveguide (8) and the balance waveguide (7). The upper stack (2) has two covers, One cover (4) encloses the driver and has a circular hole to allow the driver's (1) magnet(s) and pole piece to slide through it. The other cover (5) encloses the top stacks (2) portion of the tuning waveguide (8)

(19) The driver (1) attaches face down over the top of a circular hole (10) in the main body's upper stack (2) to provide relief for driver (1) cone excursion. The driver (1) may have a compressible foam or other suitable material (9) fixed to the perimeter of its magnet(s) structure as to provide a seal between the driver (1) and the driver cover (4). The driver (1) faces the relief hole (10) and produces sound that travels through the relief hole (10) and through the balance waveguide aperture (11) into the balance waveguide (7) and eventually to the outside of the cabinet. The rear side of the driver (1) produces sound that enters through the tuning, waveguide aperture (12) into the upper portion of the tuning waveguide (8) through the upper and lower tuning waveguide couplings (13) into the lower portion of the tuning waveguide (8) and eventually to the outside of the cabinet.

(20) FIGS. 3-8 provide drawings of an embodiment constructed according to the design of FIG. 2 in various states of assembly. FIG. 3 provides a drawing of the upper stack (2) as viewed from above with a Diamond D3 subwoofer (1) installed and without the covers (4) and (5). The tuning waveguide aperture (12) and the tuning waveguide coupling (13) are visible.

(21) FIG. 4 is a drawing of the lower stack (3) and cover (6) viewed from below showing the balance waveguide aperture (11) the balance waveguide (7) the timing waveguide (8) and the tuning waveguide coupling (13). The base (17) is not shown for clarity in this drawing.

(22) FIG. 5 is a drawing of the upper stack (2) connected to the lower stack (3) via the lower stack cover (6) as viewed from above showing the balance waveguide (7) and the tuning waveguide (8). The driver cone (1) is not present in this drawing for clarity.

(23) FIG. 6, shows the embodiment of FIG. 5 from a different angle. FIG. 6 shows the enclosure (20) with the balance waveguide aperture (10) the driver cone (1) relief hole (10) into which the transducer (1) would normally be positioned. As can be seen, the aperture (10) is significantly smaller than the hole (10). There are also included anchor studs (31) for securing the transducer in the hole (10). The tuning waveguide aperture (12) is also visible.

(24) FIG. 7 is a drawing showing the upper stack (2) with guide pieces (41) installed therein. Guide pieces (41) may be used to smooth hard corners in the various ports to better direct the acoustic waves through the waveguide and around bends. The guide pieces (41) in the depicted embodiment comprise cardboard surfaces which have been arranged into smooth curves. In this particular embodiment, the guide pieces (41) comprises a Sonotube which has been quartered into 90 degree segments and fastened to the main body using wood screws (43). The lower stack (3) may also include guide pieces (41) therein.

(25) FIG. 8 provides a drawing of the completed loudspeaker installed in the trunk of a vehicle. The upper and lower stacks (2) and (3) are visible as are the upper stack's (2) tuning waveguide cover (5), the diamond D3 subwoofer (1) of FIG. 3, the drivers enclosure cover (4), the tuning waveguide (8), and the balance waveguide (7). The cabinet (30) has attached thereto an optional audio amplifier (80) which may be used to boost signal into the speaker (1). While FIG. 8 shows the device without any finishing, further finishing to the cabinet (30) such as upholstering or veneering as those things are understood by those of ordinary skill in the art may be carried out in some embodiments.

(26) While the invention has been disclosed in connection with certain preferred embodiments, this should not be taken as a limitation to all of the provided details. Modifications and variations of the described embodiments may be made without departing from the spirit and scope of the invention, and other embodiments should be understood to be encompassed in the present disclosure as would be understood by those of ordinary skill in the art.