Lula mentioned Eric Alexander's Sigma OB (open baffle) speaker. I've had a pair for over 9 months and (as it relates to Eric's other fine work) I can tell you I am quite pleased with these! I come from 15yrs of bipolar Apogee Duetta Signatures / Hsu Research subs. These are not only better sounding (coherence!) but a steal at the price! For whatever reason they are not currently listed on the Tekton website but I'm guessing Eric could build you a pair. For all I know he may be in the middle of a new version incorporating his new multi-tweeter alignment...oh, now that I'll have to hear if it proves to be true!