Gordon,
you basically just described my speakers (pic posted earlier in thread). A Vifa XT19 loaded by a waveguide XO'd to a Seas W22 8" midbass @ 1.3k 48db/oct. Just as you said the roll off on the tweeter begins much higher than that to compensate for the 10+ db boost in output at 1.3k. Using an 8" driver avoids (somewhat) the inevitable cone breakup of a large dia. driver at higher frequencies. The other benifit of this approach is that the waveguide limits the dispersion of the tweeter to a much closer match to the midbass which is starting to beam (at 1.3k). The directivity of the entire system is (more) constantly decreasing with frequency, avoiding abrupt changes in the off axis response and power response of the system. 2 12" Peerless XLS's handle bass below 120hz. A monopole sub is used below 40hz to limit the excursion of the XLS's. The system will play excruciatingly loud without any strain on the tweeter (that I can hear).
AJ
you basically just described my speakers (pic posted earlier in thread). A Vifa XT19 loaded by a waveguide XO'd to a Seas W22 8" midbass @ 1.3k 48db/oct. Just as you said the roll off on the tweeter begins much higher than that to compensate for the 10+ db boost in output at 1.3k. Using an 8" driver avoids (somewhat) the inevitable cone breakup of a large dia. driver at higher frequencies. The other benifit of this approach is that the waveguide limits the dispersion of the tweeter to a much closer match to the midbass which is starting to beam (at 1.3k). The directivity of the entire system is (more) constantly decreasing with frequency, avoiding abrupt changes in the off axis response and power response of the system. 2 12" Peerless XLS's handle bass below 120hz. A monopole sub is used below 40hz to limit the excursion of the XLS's. The system will play excruciatingly loud without any strain on the tweeter (that I can hear).
AJ