US Patent 7088841 Subwoofer

A subwoofer having a novel component geometry that permits large voice coils and high efficiency heat transfer capability. The subwoofer comprises a frame having an outside and an inside, a central portion, radial heat sink fins, lower ventilation apertures, and a bottom portion having a bottom vent aperture. A motor unit comprising a case and a pole unit, the case having lower ventilation apertures and the pole unit having a cylindrical portion having a center aperture, wherein the cylindrical portion of the pole unit is of a diameter less than the diameter of the case, defining a first chamber area. The lower ventilation apertures of the frame, and the lower ventilation apertures of the motor unit are aligned to allow air to flow from the outside of the subwoofer into the first chamber area.