Thanks for the info. I am familiar with horn theory and hornRESP, I just like to have Wayne in on complex horn designs. The only reason I'm using stereo subwoofers is to decrease standing waves and room modes... Operating more than one subwoofer smooths frequency response over the whole room.

A 24 Hz horn would be great... I'm not seriously worried about reaching huge sensitivity levels. I just have to make sure the 1/4 wavelength and the mouth size can be accomidated. I have no idea what the 1/8th space mouth size would have to be on a 24 Hz horn, but I imagine it's fairly large!

Adam