What Do You Think . . . and How Does It Work?

i heard these speakers at AXPONA a few years ago.  it was in the madisound room that sells these kits online.  
very incredible deal for the $230 for the kit less the PVC piping.  in this case they used minidsp for the active crossovers.  
sound was deep, rich and had very good bass impact. not the last word in midrange transparency though.  

kenjit,

from an engineering standpoint a tubular shape is inherently the most rigid and deflects the least under pressure than a box shape.  
that's why pressure vessels are cylindrical- e.g. pressurized gas, liquid nitrogen storage dewars, compressed air cylinders and HVAC boilers.  
as a speaker enclosure this translates into ultra low resonance and coloration.  Magico in fact sees the value in ultra rigid enclosures by making theirs from aluminum.  
The downside of using PVC tubes for conventional speakers include the difficulty of the manufacturing process and cost of adding adaptations for stands, speaker mounting interfaces, speaker terminal interfaces and finishes.  
The higher end B&W diamond towers mimic this to some extent- they remind me of trash receptacles.