Hi George - without added source Z your driver would be 8.4cu.ft. QB3, f3~34Hz, fb~29Hz - could probably lop a bit of volume off and tune a bit lower - if it sounds good - have 95oz older Eminence kinda like Sigma with 3" voice coil and qts close - they have pretty good subjective definition in my 6.4cu.ft R-J style boxes but was using solid-state - wish could help on Eminence 15" - only have Delta Pro and discontinued 295-070 Dayton - freddy