The basic concept is a Unity horn built into bass traps. This makes it a very unobtrusive version since I was already going to build the bass traps. There is considerable volume behind the traps, since the space behind the 150mm panel does not need to be filled in.
The horn will actually be a waveguide (oblate spheroid) 60 degrees vertical x 90 degrees horizontal dispersion. It will feature a B&C DE250 compression driver, mids are yet to be decided. It will be a 3 way active design with 18" woofers. I plan to run a horn sub below the floor based on 3 x Rythmik servo kits clustered together in a tapped horn arrangement. They will achieve maximum efficiency that way.
The tricky part is to build arrange the woofer boxes so that they don't become a boundary that effectively means the bass trap is no longer very deep. Hence the bass must be free to move around them. If they filled the corner completely, then the traps would have an effective depth that would make them midrange absorbers and not bass traps. I have them in two boxes joined at the middle to avoid difficult cuts in a design that has the Unity and woofers isolated.