US3684051A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic duct speaker system
Assignee: Individual
•
Filing: 1970-10-08
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Granted: 1972-08-15
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Expires: 1990-10-08
Abstract
Abstract A bass reflex cabinet speaker assembly, e.g. as for use with stereo and high-fidelity speaker systems, having a port coupling the cabinet to the air, and having mounted within said port an acoustic duct formed of a large number of contiguous conduits each of a different length, differing progressively from the center to the periphery of the duct and preferably so formed that the end of the duct is in a concave or convex parabolic shape. In the most advantageous forms of the invention, a flexible corrugated paperboard sheet-or other sheet having a series of conduits therein-may be cut generally obliquely either rectilinearly or curvilinearly and rolled up to form the acoustical duct.
Inventors
- 👤 Herbert J Hopkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:13
CPC Classifications
H; H04; H04R; H04R1/00; H04R1/20; H04R1/22; H04R1/28; H04R1/2807; H04R1/2815; H04R1/2823; H04R1/2826
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
74 words
In a loudspeaker cabinet of the bass-reflex type, the improvement wherein an acoustic duct mounted in a wall thereof, and thereby forming a conduit between the interior of the loudspeaker cabinet and the surrounding air, is formed of a large number of conduits of differing lengths, all said conduits being formed into an integral acoustic duct of generally cylindrical shape said conduits being of progressively different lengths between the center and the circumference thereof.
Claim 2
Dependent Claim
74 words
In a loudspeaker cabinet of the bass-reflex type, the improvement wherein an acoustic duct mounted in a wall thereof, and thereby forming a conduit between the interior of the loudspeaker cabinet and the surrounding air, is formed of a large number of conduits of differing lengths, all said conduits being formed into an integral acoustic duct of generally cylindrical shape said conduits being of progressively different lengths between the center and the circumference thereof.
Claim 3
Dependent Claim
45 words
A loudspeaker as defined in claim 1 wherein said acoustic duct is formed of at least one continuous flexible sheet so cut that the ends of the conduits terminating within the loudspeaker cabinet all terminate at different distances from the wall of said loudspeaker cabinet.
Claim 4
Dependent Claim
32 words
A loudspeaker as defined in claim 2 wherein the flexible sheet is so cut that the ends of the conduits terminating within the loudspeaker cabinet form a parabola-shaped end on said duct.
Claim 5
Dependent Claim
36 words
A loudspeaker as defined in claim 1 wherein said large number of conduits of differing lengths are formed by cutting a flexible corrugated sheet at an angle and rolling said sheet up to form a cylinder.
Claim 6
Dependent Claim
15 words
A loudspeaker as defined in claim 4 wherein said flexible corrugated sheet is corrugated paperboard.
Claim 7
Dependent Claim
86 words
In combination with a loudspeaker cabinet of the bass reflex type, a generally cylindrical acoustic duct mounted in a wall of said cabinet, said duct comprising a large number of elongated, small diameter conduits all of differing lengths, said conduits being from about three quarters of an inch to about 12 inches in length, said duct being from about 2 inches to about 10 inches in diameter and said conduits being of progressively different lengths from the center to the periphery of said cylindrical acoustic duct.
Claim 8
Dependent Claim
86 words
In combination with a loudspeaker cabinet of the bass reflex type, a generally cylindrical acoustic duct mounted in a wall of said cabinet, said duct comprising a large number of elongated, small diameter conduits all of differing lengths, said conduits being from about three quarters of an inch to about 12 inches in length, said duct being from about 2 inches to about 10 inches in diameter and said conduits being of progressively different lengths from the center to the periphery of said cylindrical acoustic duct.
Claim 9
Dependent Claim
27 words
An acoustic duct as defined in claim 6 wherein said ducts are formed of a sheet of corrugated material cut generally obliquely and rolled up upon itself.
Claim 10
Dependent Claim
16 words
An acoustic duct as defined in claim 6 wherein said ducts are formed of corrugated paperboard.
Claim 11
Dependent Claim
38 words
An acoustic duCt as defined in claim 6 wherein said cylindrical duct is formed by adhering together at least about two hundred tubes to form said conduit, each tube being of a different length but of identical diameter.
Claim 12
Dependent Claim
100 words
In a low frequency loudspeaker cabinet having a port for balancing sound to improve reception: a close packed mass of elongated tubes, jointly defining an acoustic duct, said duct having one end mounted in said port for passing sound from inside said cabinet through said tubes to outside said cabinet; each said tube being of a different length, and having a different resonant frequency from the remaining said tubes in said mass; said tubes varying progressively in length from the center to the periphery of said mass, whereby a broader resonant band results which minimizes self resonance within said duct.
Claim 13
Dependent Claim
100 words
In a low frequency loudspeaker cabinet having a port for balancing sound to improve reception: a close packed mass of elongated tubes, jointly defining an acoustic duct, said duct having one end mounted in said port for passing sound from inside said cabinet through said tubes to outside said cabinet; each said tube being of a different length, and having a different resonant frequency from the remaining said tubes in said mass; said tubes varying progressively in length from the center to the periphery of said mass, whereby a broader resonant band results which minimizes self resonance within said duct.
Claim 14
Dependent Claim
24 words
An acoustic duct as specified in claim 10, wherein: each said tube is of uniform cross section from one end to the other thereof.
Claim 15
Dependent Claim
30 words
An acoustic duct as specified in claim 10, wherein: said tubes are formed by the corrugated flutes and liner of a corrugated paperboard-like sheet material rolled into a helical configuration.
Claim 16
Dependent Claim
37 words
An acoustic duct as specified in claim 10, wherein: the said one end of said duct is flat and planar, said tubes are in parallelism, and the said other end of said duct defines a parabolic configuration.
Claim 17
Dependent Claim
25 words
An acoustic duct as specified in claim 10 wherein: said duct is of predetermined length and diameter to tune the cabinet to a desired frequency.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-15 | 1976-02-14 | 1976-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-15 | 1980-02-14 | 1980-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-15 | 1984-02-14 | 1984-08-15 | $7700.00 | Window Closed / Lapsed |