Uh-oh - I'm in trouble. I don't want to steal Chris's fire. But what the calculator does is to tell you the electrical equivalents R,L and C when given Free-air Qms and Zmax. Maybe if we grovel and beg, he'll add functionality to input other driver and box parameters so that it can calculate fo, fl and fh and provide electrical equivalents for sealed and bass-reflex systems too. Now with that, I think Chris is probably going to kill me for opening this up for discussion.About the midrange horn, I'm planning to load with the JBL 2012 or Delta 10. Something for the Alpha 6 or JBL 2115 is sweet too, but I'm working on something a little larger.