Is there a preferred shape for loudspeaker enclosures?
There are a number of shapes that improve performance and some that cause distinct degradation in performance. For single, full-range drivers a sphere is the ideal shape for an enclosure because the curved surfaces avoid the diffraction effects of cabinet edges, which bend sound waves in a manner dependent on frequency. For multi-way loudspeaker systems, spheres are usually impractical because of the large size needed and because of the precise orientation required for optimal listening. Conventional enclosures work best mounted flush into a wall where diffraction is controlled by virtue of the wall surface, and for free-standing enclosures, tilting, angled and curving surfaces may be employed to help reduce or control edge diffraction. As for subwoofers specifically; slightly angled enclusures ensure that there are minimal standing waves inside the enclosure; you want to stay away from having too many parallel sides. It is best to avoid enclosure dimensions that are multiples of each
