Correct me if I'm wrong. Using the ratios provided in your PiAlign document, the horn mouth would be 18"x24", giving a total area of 432 sqr in.

Area = ((speed sound/freq)^2)/(4*pi)

However, because the horn sits on the floor, effective area doubles to 864 sqr inch, giving me a cutoff of 130Hz.

Does this mean that by putting the OnePi into a folded horn, it will end up having worst bass response? Only frequencies above 130Hz will be increased by the 3dB that the horn provides?

Gar.