The woofers, wired in series, met up with a single inductor, resulting in a 1st order electrical slope. I stress electrical slope, as opposed to actual roll-off, because I think there's a bit of smart planning in this. If the mid-bass drivers have sufficient bandwidth to accomplish this, problems can still arise if not addressed. Larger diaphragms beam higher frequencies. The larger the diaphragm, and the higher the frequency, the more it beams.
Speakers begin to beam as the wavelength approaches the diaphragm size.
A mid-bass with response approaching 4 kHz, however, will beam. Like I said, clever. Room response will vary from room to room, and location to location. I tried many positions, and found the best match several feet from the rear wall for bass response, toed in considerably for the most articulate and defined imaging capability. Clever is probably the most appropriate term.