Here is a link to measured response and impedance files for the TD12M and the SEOS12 drivers, these are for measurement with the FRONT edge of the SEOS12 being on the same plane with the TD12M.. if the TD12M is modeled using the Z offset shown in the Notes.txt file. http://libinst.com/SEOS/SEOS12_TD12M/ The curves were taken at 22degrees off the horizontal axis, at the tweeter's vertical center. The 22deg offset is why the very high treble drops like that. I figure that since these will always be used toed-in (RIGHT???) that 22deg is a better angle to adjust for. This was with a driver kindly loaned by pgwalsh over at AVS, and a phase plug supplied by HomeTheaterDoc. I also modeled (but didn't build) a crossover design for these drivers, here are the simulated freq response and impedance curves: (ignore the glitch around 800Hz, that's a PCD thing) This is the schematic: The schematic file is at https://www.circuitlab.com/circuit/4638dz/td12m-seos12/ Very nice driver, that too. Heavy suckers, though!