Frequency selective acoustic waveguide damping

• US 6,278,789 B1
• Filed: 05/06/1993
• Issued: 08/21/2001
• Est. Priority Date: 05/06/1993
• Status: Expired due to Term

• Current Assignee: Bose Corporation
• Original Assignee: Bose Corporation
• Inventors: Potter, Dewey
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Harvey, Dionne N.
• Application Number:
  US08/058,478
• Time in Patent Office: 3,029 Days
• Field of Search: 381/24, 381/158, 381/154, 381/90, 381/88, 381/337, 381/351, 381/338, 381/353, 381/348, 381/395, 181/156, 181/187, 181/189, 181/190, 181/179, 181/151, 181/198
• US Class Current: 381/338
• CPC Class Codes: H04R 1/2857 for loudspeaker transducers

Abstract

An acoustic waveguide loudspeaker system has an electroacoustical transducer having a vibratile surface. An acoustic waveguide has a first end open and a second end adjacent to the vibratile surface and an effective length corresponding substantially to a quarter wavelength at the lowest frequency of pressure wave energy to be transmitted between the first and second ends. Damping material in the waveguide near the vibratile surface is positioned so as to negligibly attenuate bass frequency energy while of sufficient volume to damp peaks at higher frequencies above the range of the bass frequency energy.

Claims

1. An acoustic waveguide loudspeaker system comprising:

an electroacoustical transducer having a vibratile surface,

an acoustic waveguide having a first end open and a second driver end adjacent to said vibratile surface and an effective length corresponding substantially to a quarter wavelength at the lowest frequency of pressure wave energy to be transmitted between said first and second ends,

and damping material in said waveguide only at said driver end extending into said waveguide for a predetermined length near said vibratile surface constructed and arranged and positioned so as to negligibly attenuate bass frequency energy while of sufficient volume to damp peaks at higher frequencies above the range of said bass frequency energy,

the length of said waveguide between said first end and said damping material being significantly greater than said predetermined length.

2. An acoustic waveguide loudspeaker system in accordance with claim 1 wherein said damping material is polyester.

3. An acoustic waveguide loudspeaker system in accordance with claim 1 wherein said acoustic waveguide comprises a plurality of contiguous waveguide portions formed by a first set of waveguide walls generally perpendicular to said vibratile surface and a second set of waveguide walls generally parallel to said vibratile surface.

4. An acoustic waveguide loudspeaker system in accordance with claim 3 wherein a first of said waveguide portions near said vibratile surface is substantially filled with said damping material.

5. An acoustic waveguide loudspeaker system in accordance with claim 1 wherein a volume of said waveguide nearest said vibratile surface is substantially filled with said damping material.

6. An acoustic waveguide loudspeaker system in accordance with claim 3 wherein a last of said waveguide portions is separated from a first group of said waveguide portions by a second group of said waveguide portions formed by said waveguide walls generally parallel to said vibratile surface.

7. An acoustic waveguide loudspeaker system comprising:

an electroacoustical transducer having a vibratile surface,

an acoustic waveguide having a first end open and a second driver end adjacent to said vibratile surface and an effective length corresponding substantially to a quarter wavelength at the lowest frequency of pressure wave energy to be transmitted between said first and second ends,

and damping material in said waveguide at said driver end extending into said waveguide for a predetermined length near said vibratile surface constructed and arranged and positioned so as to negligibly attenuate bass frequency energy while of sufficient volume to damp peaks at higher frequencies above the range of said bass frequency energy,

the length of said waveguide between said first end and said damping material being significantly greater than said predetermined length,

wherein said acoustic waveguide comprises a plurality of contiguous waveguide portions formed by a first set of parallel waveguide walls generally perpendicular to said vibratile surface and a second set of parallel waveguide walls generally parallel to said vibratile surface,

wherein a last of said waveguide portions is separated from a first group of said waveguide portions by a second group of said waveguide portions formed by said waveguide walls generally parallel to said vibratile surface,

wherein said last of said waveguide portions is separated from said second group of said waveguide portions by a generally L-shaped waveguide portion.

8. An acoustic waveguide loudspeaker system comprising:

an electroacoustical transducer having a vibratile surface,

an acoustic waveguide having a first end open and a second driver end adjacent to said vibratile surface and an effective length corresponding substantially to a quarter wavelength at the lowest frequency of pressure wave energy to be transmitted between said first and second ends,

wherein said acoustic waveguide comprises a plurality of contiguous waveguide portions formed by a first set of parallel waveguide walls generally perpendicular to said vibratile surface and a second set of parallel waveguide walls generally parallel to said vibratile surface,

wherein a last of said waveguide portions is separated from a first group of said waveguide portions by a second group of said waveguide portions formed by said waveguide walls generally parallel to said vibratile surface,

wherein said last of said waveguide portions is separated from said second group of said waveguide portions by a generally L-shaped waveguide portion, and

a second electroacoustical transducer having a vibratile surface adjacent to the last of said waveguide portions and said L-shaped waveguide portion,

said first and second electroacoustical transducers having first and second axes respectively generally perpendicular to an associated vibratile surface,

said first and second axes angled slightly away from each other.