Say Wayne: I'm assuming the cabinet volume for the theater 4 bass reflex is the same as with the 7 pi corner horn using the delta 15 eminence driver. So what if one had the HF driver and horn housed separately, unattached atop the the bass cab. If you want the theater 7 you'd use removable panels that can be screwed or bolted above and below the speaker to form the doghouse reflector of the corner horn or you could undo the panels for the theater 4 and flip er round. But how much of the crossover parts share compatability? If it's just a matter of a few resistors or caps for the compensation network then a flip of a switch could finish the change over.
Wow alright! I don't know if a corner horn will work in my house or not as one speaker would have to be in another adjoining room, but this would give some flexibility if it dosn't sound right without having to build another cabinet. Let me pontificate my praise for your friendly help on this forum. Thanks! Rick