Since I really like the Altec Model 14 for the mains at 114 max SPL (4 ft), I will use one Pi 7-18" as a subwoofer only. I build my own electronic crossovers and filters using Electronic Workbench V4.1 software and I get great predictable results. It has a Bode plotter (spectrum analyzer) that gives -3Db points, etc. 3rd order filters are no problem and since this subwoofer will be behind the left main at a diagonal, I will need to have as steep a crossover as possible, maybe 80Hz or so. Bi-amping and electronic filters are so great, no passive network loss.

I looked at your Pi 7 design (math) and it looks like "D" is about 12". That constant seems to make the exterior box dimensions come out about 49" x 25" x 13". Do you sell the plans for this design? If so, I would like a set.

I will sell the JBL 4508 W/2226J's here in Atlanta as I really have no use for them. I couldn't believe that JBL had free shipping on this 100+lb speaker!

Thank you again for responding,

Richard