How low does this thing go? How does it compare to the F-20? As I posted earlier in another thread, I would love to build a horn sub just to try out, it might actually work well as a riser like the OP has done. I was intending on building a riser anyway, if for nothing more than getting up off my concrete floor in order to get the more tactical sensation!
I seriously need to learn how to simulate and design horn subs as I do not believe that there are any existing designs that would fit my goals of having massive output for >20hz and to be slim enough to work as a riser.