Lightweight speaker enclosure
A speaker enclosure having a substantially seamless rigid outer skin, a middle sound absorbing layer, and a substantially seamless inner skin results in a lightweight speaker having sound absorbing characteristics. The speaker enclosure is comprised of two basic parts, a box section and a baffle section where each of these sections include a rigid outer skin, the middle sound absorbing layer and a seamless inner skin and are made according to the same method. The outer skin is formed from a layer of sheet molding compound, the middle sound absorbing layer includes pieces of honeycomb material, and the inner skin is formed from a layer of sheet molding compound. The layers of material are placed into a mold and then cured through vacuum bagging and heating thereby producing a strong, lightweight speaker enclosure made of materials which attenuate the transmission and retransmission of errant sound waves in the enclosure thereby reducing distortion of the sound signal produced by the speaker.
1. A speaker box comprising:
an outer layer of a cured sheet molding compound;
an inner layer of a cured sheet molding compound, wherein the outer and inner layers of the cured sheet molding compound are contoured to define an interior space to receive speaker components;
a sound absorbing layer, having a compression threshold along a first direction that is more than a compression threshold along a second direction that is generally perpendicular to the first section, interposed between the outer and inner layers of the cured sheet molding compound;
a continuous adhering layer interposed between the outer layer and the inner layer, wherein the continuous adhering layer is formed under a selected pressure below the compression threshold of the sound absorbing layer along the first direction, wherein the continuous adhering layer reduces errant sound vibrations.
2. The speaker box of claim 1 , further comprising a layer of film adhesive interposed between the sound absorbing layer and the continuous adhering layer.
3. The speaker box of claim 1 , wherein the continuous adhering layer substantially adheres to inner and outer surfaces of the sound absorbing layer to form a substantially uniform-thickness structure.
4. The speaker box of claim 1 , wherein the sound absorbing layer comprises a material that defines a plurality of open structures each containing a gas.
5. The speaker box of claim 3 , wherein the continuous adhering layer comprises at least one piece of sheet molding compound (SMC).
6. A speaker box comprising:
an outer layer of a cured sheet molding compound;
an inner layer of a cured sheet molding compound, wherein the outer and inner layers of the cured sheet molding compound are contoured to define an interior space to receive speaker components;
a continuous frequency attenuation layer interposed between the outer layer and the inner layer, wherein the continuous frequency attenuation layer absorbs acoustical energy through a plurality of discontinuous layers;
wherein the discontinuous layers are able to resist compression along a first direction more than along a second direction that is generally perpendicular to the first direction.
7. The speaker box of claim 1 , wherein the discontinuous layers comprises pieces of honeycomb material and at least one sheet molding compound.
8. The speaker box of claim 7 , wherein the pieces of honeycomb material and the sheet molding compound substantially adhere to each other to form a single substantially seamless layer of uniform thickness.
9. A method of forming a speaker enclosure using a mold that resembles the exterior dimensions of the enclosure, comprising:
forming an outer layer by cutting and folding a single sheet of sheet molding compound to substantially conform to the dimensions of the mold;
forming an inner layer by cutting and folding a single sheet of sheet molding compound to substantially conform to the dimensions of the mold;
positioning a middle layer, having a compression threshold, interposed between the outer layer and the inner layer, by placing sound absorbing material substantially conforming to the dimensions of the mold;
curing the enclosure by exposing the mold, the outer layer, the inner layer, and the middle layer to a temperature and a pressure sufficient to cure the outer layer and the inner layer to form a substantially rigid uniform structure, wherein the pressure is less
than the compression threshold of the middle layer.