Minimum CSA 65in^2, but more is good, anywhere to 140in^2. Bigger is better.Length, 130 inches, or 65 inches as folded pipe. Internal DIM's ex: 6.5 X 10 X 65 = High WAF BIB. Line gain @ Fs =10db (!!!) this is before room loading, which generally adds ~2-3db. (no kidding)
Zo Driver 27.75 inches from sealed end.
FR ~Flat to 34Hz, F5=30Hz. *this is a very full range horn alignment. This calc is VERY similar to the Jordan model on www.zillaspeak.com/bib.asp
I will attempt to learn how to post the FRP to this forum. (techno-peasant)