I finished the report for my Acoustics class that discusses the effects of enclosure shape on speaker response. I am hesitant to post it to the forum because the bibliography is not up to par. Basically, I found that in terms of diffraction, the sphere is best in terms of shape. Using felt however, is just as good or better when used on a flat baffle. So, by rounding the edges of the baffle and using felt would be the best bet (*Flush mounting drivers is very very important too*). For internal resonances, all the evidence pointed to an enclosure that did not have parallel walls. Tapering the walls seemed to be very good, whether done like the B&W Nautilus or the Sonus Faber Amatis. As far as materials go, wood is the best. MDF or hardwoods of significant thickness will prevent enough transmission through the walls of the cabinet into the listening area to keep the desired sound unaffected. I originally thought that a more rigid material like marble would be the best, but in the case of marble, almost all transmission through the walls is prevented and a buildup of energy on the inside will almost definitely make its way back out through the cone (very bad). I didn't see any designs using this technique, but a cabinet with wood on the inside and marble on the outside, might take advantage of the benefits of both materials. Of course, some internal dampening is required to achieve the best results, although the amount is drastically decreased when you use a modified shape. The paper addresses time-alignment of the drivers, which did not seem to be a big problem in loudspeakers, unless you are far from the speakers. The best results are achieved by staying relatively close to the speakers. Slanting of the front baffle didn't seem like a good solution because it pointed the speakers at the ceiling. Separate enclosures staggered the proper distances worked best for time-alignment, but could add more problems diffraction-wise. kingdaddy's SST8's look like they would do a relatively good job in taking care of both time-alignment and diffraction. Those are the only factors I took into account for the paper, I would be happy to research other factors if anyone is interested. I can email a copy of the paper to anyone who is interested also. Hope some of the information is helpful.
Austin
Austin