Loudspeaker system having bass response range below system resonance

Claim 2

A loudspeaker system comprising: first cavity means constituted by an enclosing wall means and confined air space and functionally operable as an acoustic capacitance; loudspeaker means mounted to and forming a portion of said wall means of said first cavity means; second cavity means constituted by an enclosing wall means and confined air space and functionally operable as an acoustic capacitance; coupling aperture means functionally operable as an acoustic inertance linking the acoustic capacitance of said first cavity to the acoustic capacitance of said second cavity; the inertance of said coupling aperture means producing a value of acoustic reactance that is equal to and of opposite sign to the acoustic reactance produced by the effective acoustic capacitance of said second cavity means at some specific frequency, F; port aperture means in a side wall means functionally operable as an acoustic inertance linking the acoustic capacitance of one of said cavities to the radiation impedance of the exterior system atmosphere; said loudspeaker system producing a radiated sound pressure vs. frequency curve characterized by a band of response below F, wherein radiation from said port aperture means supports the front-wave radiation from said loudspeaker; and wherein the sum of the effective internal air space of said first cavity means plus the effective internal air space of said second cavity means, the effective cone area of said loudspeaker means, and F are related substantially in accordance with the following formula: V 2.9 A/F + 80% - 40% Where: V total effective internal air space of cavity means, in cubic feet A effective piston area of loudspeaker cone, in square inches F frequency at which the reactance of said coupling aperture means is equal to and of opposite sign to that of said second cavity means.

Claim 3

System as in claim 1, wherein the ratio of said internal air space of said first cavity means to that of said second cavity means falls within the range of 0.4 to 1.7.

Claim 4

System as in claim 1, wherein said coupling aperture means is an acoustic inertance of relatively good efficiency substantially free of acoustic resistance.

Claim 5

System as in claim 1, wherein said port aperture means is in the enclosing wall means of said first cavity means.

Claim 6

System as in claim 1, wherein said port aperture means is in the enclosing wall means of said second cavity means.

Claim 7

System as in claim 2, wherein said coupling aperture means is an element of acoustic inertance of relatively good efficiency substantially free of acoustic resistance.

Claim 8

System as in claim 1, wherein said port aperture means is located in said first cavity means; and including also deflection means cooperatively operable with said port aperture means whereby sound energy emanating from said port aperture means is directed toward the area immediately in front of said loudspeaker means.

Claim 9

A loudspeaker system comprising: first cavity means constituted by an enclosing wall means and confined air space and functionally operable as an element of acoustic capacitance; loudspeaker means mounted to and forming a portion of said wall means of said first caviTy means; second cavity means constituted by an enclosing wall means and confined air space adjoined to said first cavity means and functionally operable as an element of acoustic capacitance; coupling aperture means functionally operable as an acoustic inertance linking the acoustic capacitance of said first cavity to the acoustic capacitance of said second cavity; the inertance of said coupling aperture means producing a value of acoustic reactance that is equal to and of opposite sign to the acoustic reactance produced by the acoustic capacitance of said second cavity means at a specific frequency F; port aperture means functionally operable as an element of acoustic inertance linking the acoustic capacitance of one of said cavities to the radiation impedance of the exterior system atmosphere; said loudspeaker system, when unmodified, producing a radiated sound pressure vs. frequency curve characterized by a response band below F wherein port aperture radiation is additive to said loudspeaker front-wave radiation, followed by a valley in response in the region above F; second cavity modification means for modifying said second cavity means and said coupling aperture means to cooperatively function as band-pass filter means and comprising; division means separating said second cavity means into first sub-cavity means and second sub-cavity means, said first sub-cavity means and said second sub-cavity means each functionally operable as elements of acoustic capacitance; the sum of the acoustic capacitance of said first sub-cavity means being equal to the unmodified said second cavity means; said division means incorporating sub-cavity coupling aperture means functionally operable as an element of acoustic inertance and linking the acoustic capacitance of said first sub-cavity means to the acoustic capacitance of said second sub-cavity means; the acoustic reactance produced by the inertance of said sub-cavity coupling aperture means being equal to and of opposite sign to the acoustic reactance produced by the acoustic capacitance of said second sub-cavity means at a frequency in the region of said response valley; the acoustic inertance of said sub-cavity coupling aperture means and the acoustic capacitance of said second sub-cavity means cooperatively functioning as termination arm in said band-pass filter means; the acoustic inertance of said coupling aperture means and the acoustic capacitance of said first sub-cavity coupling aperture means cooperatively functioning as transmission arm means in said band-pass filter means; the acoustic reactance produced by the acoustic inertance of said coupling aperture means being equal to and of opposite sign to the acoustic reactance produced by the acoustic capacitance of said first sub-cavity means at a frequency in the region of said response valley; wherein, at said frequency F, reactance produced by the inertance of said sub-cavity coupling aperture means and the capacitance of said second sub-cavity means as combined with the reactance produced by the capacitance of said first sub-cavity means results in a value of acoustic reactance that is substantially equal to and of opposite sign to the value of reactance produced by the inertance of said coupling aperture means as modified; said termination arm means incorporating substantial damping means; whereby said band-pass filter means selectively absorbs and dissipates sound energy in the frequency region of said response valley; and whereby said band-pass filter means functions essentially in the same manner as the unmodified said second cavity means and the unmodified said coupling aperture means in the frequency region below said frequency F, said modification means having substantially no effect on said response band below F, while raising substantially said valley.

Claim 10

A loudspeaker system comprising: first cavity means constituted by an enclosing wall means and confined air space and functionally operable as an element of acoustic capacitance; loudspeaker means mounted to and forming a portion of said wall means of said first caviTy means; second cavity means constituted by an enclosing wall means and confined air space adjoined to said first cavity means and functionally operable as an element of acoustic capacitance; coupling aperture means functionally operable as an acoustic inertance linking the acoustic capacitance of said first cavity to the acoustic capacitance of said second cavity; the inertance of said coupling aperture means producing a value of acoustic reactance that is equal to and of opposite sign to the acoustic reactance produced by the acoustic capacitance of said second cavity means at a specific frequency F; port aperture means functionally operable as an element of acoustic inertance linking the acoustic capacitance of one of said cavities to the radiation impedance of the exterior system atmosphere; said loudspeaker system, when unmodified, producing a radiated sound pressure vs. frequency curve characterized by a response band below F wherein port aperture radiation is additive to said loudspeaker front-wave radiation, followed by a valley in response in the region above F; second cavity modification means for modifying said second cavity means and said coupling aperture means to cooperatively function as band-pass filter means and comprising; division means separating said second cavity means into first sub-cavity means and second sub-cavity means, said first sub-cavity means and said second sub-cavity means each functionally operable as elements of acoustic capacitance; the sum of the acoustic capacitance of said first sub-cavity means being equal to the unmodified said second cavity means; said division means incorporating sub-cavity coupling aperture means functionally operable as an element of acoustic inertance and linking the acoustic capacitance of said first sub-cavity means to the acoustic capacitance of said second sub-cavity means; the acoustic reactance produced by the inertance of said sub-cavity coupling aperture means being equal to and of opposite sign to the acoustic reactance produced by the acoustic capacitance of said second sub-cavity means at a frequency in the region of said response valley; the acoustic inertance of said sub-cavity coupling aperture means and the acoustic capacitance of said second sub-cavity means cooperatively functioning as termination arm in said band-pass filter means; the acoustic inertance of said coupling aperture means and the acoustic capacitance of said first sub-cavity coupling aperture means cooperatively functioning as transmission arm means in said band-pass filter means; the acoustic reactance produced by the acoustic inertance of said coupling aperture means being equal to and of opposite sign to the acoustic reactance produced by the acoustic capacitance of said first sub-cavity means at a frequency in the region of said response valley; wherein, at said frequency F, reactance produced by the inertance of said sub-cavity coupling aperture means and the capacitance of said second sub-cavity means as combined with the reactance produced by the capacitance of said first sub-cavity means results in a value of acoustic reactance that is substantially equal to and of opposite sign to the value of reactance produced by the inertance of said coupling aperture means as modified; said termination arm means incorporating substantial damping means; whereby said band-pass filter means selectively absorbs and dissipates sound energy in the frequency region of said response valley; and whereby said band-pass filter means functions essentially in the same manner as the unmodified said second cavity means and the unmodified said coupling aperture means in the frequency region below said frequency F, said modification means having substantially no effect on said response band below F, while raising substantially said valley.

Claim 11

System as in claim 8, wherein the ratio of the acoustic capacitance of said first caviTy means to the acoustic capacitance of said second cavity means falls within the range of 0.4 to 1.7.

Claim 12

System as in claim 8, wherein said coupling aperture means is an acoustic inertance of relatively good efficiency substantially free of acoustic resistance.

Claim 13

System as in claim 8, wherein the sum of effective air space of said first cavity means plus the effective air space of said second cavity means, the effective cone area of said loudspeaker means, and the frequency F are related substantially in accordance with the following formula: V 2.9 A/F + 80% - 40% Where: V total effective internal air space of cavity means in cubic feet A effective piston area of loudspeaker cone in square inches F frequency at which the reactance of said coupling aperture means is equal to and of opposite sign to that of said second cavity means.

Claim 14

System as in claim 8, wherein said port aperture means is located in said enclosing wall means of said first cavity means.

Claim 15

System as in claim 8, wherein said port aperture means is located in said enclosing wall means of said first sub-cavity means; and wherein said port aperture means is functionally operable as an element of acoustic inertance linking the acoustic capacitance of said first sub-cavity means to the radiation impedance of the external system atmosphere.

Claim 16

System as in claim 8, wherein said port aperture means is located in said first cavity means; and including also deflection means cooperatively operable with said port aperture means, whereby sound energy emanating from said port aperture means is directed toward the area immediately in front of said loudspeaker means.

Claim 17

A loudspeaker system comprising: first cavity means constituted by an enclosing wall means and confined air space and functionally operable as an element of acoustic capacitance; loudspeaker means mounted to and forming a portion of said wall means of said first cavity means; second cavity means constituted by an enclosing wall means and confined air space adjoined to said first cavity means and functionally operable as an element of acoustic capacitance; coupling aperture means functionally operable as an acoustic inertance linking the acoustic capacitance of said first cavity to the acoustic capacitance of said second cavity; the inertance of said coupling aperture means producing a value of acoustic reactance that is equal to and of opposite sign to the acoustic reactance produced by the effective acoustic capacitance of said second cavity means at a specific frequency F; port aperture means functionally operable as an element of acoustic inertance linking the acoustic capacitance of one of said cavity means to the radiation impedance of the exterior system atmosphere; said loudspeaker system, when unmodified, producing a radiated sound pressure vs. frequency curve characterized by a response band below F, wherein port aperture radiation is additive to said loudspeaker front wave radiation, followed by a valley in response in the region above F; second cavity modification means for modifying said second cavity means and said coupling aperture means so that their cooperative function is essentially that of a single cavity means and single aperture means in the frequency region below F, while also functioning as a frequency selective sound energy absorption means in the frequency region of said response valley, said modification means having substantially no effect on said response band below F, while raising substantially said valley.

Claim 18

A loudspeaker system comprising: first cavity means constituted by an enclosing wall means and confined air space and functionally operable as an element of acoustic capacitance; loudspeaker means mounted to and forming a portion of said wall means of said first cavity means; second cavity means constituted by an enclosing wall means and confined air space adjoined to said first cavity means and functionally operable as an element of acoustic capacitance; coupling aperture means functionally operable as an acoustic inertance linking the acoustic capacitance of said first cavity to the acoustic capacitance of said second cavity; the inertance of said coupling aperture means producing a value of acoustic reactance that is equal to and of opposite sign to the acoustic reactance produced by the effective acoustic capacitance of said second cavity means at a specific frequency F; port aperture means functionally operable as an element of acoustic inertance linking the acoustic capacitance of one of said cavity means to the radiation impedance of the exterior system atmosphere; said loudspeaker system, when unmodified, producing a radiated sound pressure vs. frequency curve characterized by a response band below F, wherein port aperture radiation is additive to said loudspeaker front wave radiation, followed by a valley in response in the region above F; second cavity modification means for modifying said second cavity means and said coupling aperture means so that their cooperative function is essentially that of a single cavity means and single aperture means in the frequency region below F, while also functioning as a frequency selective sound energy absorption means in the frequency region of said response valley, said modification means having substantially no effect on said response band below F, while raising substantially said valley.

Claim 19

System as in claim 15, wherein said second cavity means is functionally operable as a band-pass filter means, and includes: division means separating said second cavity means into first sub-cavity means and second sub-cavity means, said first sub-cavity means and said second sub-cavity Means each functionally operable as elements of acoustic capacitance.

Claim 20

System as in claim 15, wherein the ratio of the acoustic capacitance of said first cavity means to the acoustic capacitance of said second cavity means falls within the range of 0.4 to 1.7.

Claim 21

System as in claim 15, wherein said coupling aperture means functions as an acoustic inertance of relatively good efficiency.

Claim 22

System as in claim 15, wherein the sum of the effective air space of said first cavity means plus the effective air space of said second cavity means, the effective cone area of said loudspeaker means, and the frequency Fr-C2 are related substantially in accordance with the following formula: V 2.9 A/F + 80% - 40% Where: V total effective internal air space of cavity means in cubic feet A effective piston area of loudspeaker cone in square inches F frequency at which the reactance of said coupling aperture means is equal to and of opposite sign to that of said second cavity means.

Claim 23

System as in claim 15, wherein said port aperture means is located in said enclosing wall means of said first cavity means.

Claim 24

System as in claim 15, wherein said port aperture means is located in said enclosing wall means of said second cavity means; and wherein said port aperture means is functionally operable as an element of acoustic inertance linking the acoustic capacitance of said first sub-cavity means to the radiation impedance of the external system atmosphere.

Claim 25

System as in claim 15, and the incorporation of deflection means cooperatively operable with said port aperture means, whereby sound energy emanating from said port aperture means is directed toward the area immediately in front of said loudspeaker means.