I get many e-mails asking about using a Sphere as the best shape for a loudspeaker. A sphere is clearly a better shape than a rectangle. One thing to consider is that there are no speakers which are truly spheres. The reason is that the area where the driver is flat and not round. This means that the sphere will not act like a complete sphere but rather more like a semi-sphere.
Most sphere speakers are acoustic suspension speakers.
This means that the energy trapped in the speaker will try to find the weakest point to come out of the cabinet. The weakest point will be the driver. The nOrh drum combines a semi-sphere. The energy inside the drum is funneled to the port. The port is tuned so that at the resonate frequency of the cabinet, the port is producing 50 per cent of the bass.