At the same time the loudspeaker system has to present the proper sound stage image to all listeners in the room. It must properly control the pattern of sound radiated into the listening space. Three identical front main speakers are needed to provide a full performance acoustic image at all listening positions.
I'm calling it "Der Blitzhornlautsprecher". The bass horn used is the LABsubwoofer v3.0 which is thoroughly described on this web site. The centrally located horn mouth provides a great sound stage and the sound blends perfectly with the top speakers. The cat knows better than to sleep in the bass horn.
The three top speakers are SPL-td2's, an updated model of the td1 from Sound Physics Labs. They are a special multi-driver horn design referred to as a "Unity Summation Aperture". They are described here by the designer Tom Danley and also in the patent. They represent the best "point source" loudspeaker configuration available in my opinion.
This speaker system is capable of extreme sound pressure levels and must be used with caution. The tremendous headroom results in a very big, clean, and effortless sound quality.