Are you running the driver in the center "fullrange" and using some kind of crossover(s) on the supertweeter and bass driver?

I think that setup is the reason why some persons prefer the name "wideband" to "fullrange" for drivers... Cuz it does sound funny to augment bass with a 15 woofer and treble with a supertweeter, if the driver is "fullrange"... It took me awhile to understand what benefit such a setup could have over a typical threeway design... I am fascinated with the concept though and hope to assemble, or at least audition, such a system some day...

Also are you using the same amp to run the Supertweeter and the widebander?