You wrote:

>> Push pull mounting would cancel the second H (like using a push
>> pull transformer vs single ended) however of all the harmonics the
>> second is the least objectionable. That’s no reason not to do it
>> how ever.

Yes, that's what the shorting ring on a high-quality loudspeaker does too. That's why I asked Eminence to build the B12. The push-pull arrangement might actually work better at low frequencies though. We'll see.

As for the expansion of the room from the corner, I did some math and found it to be conical (of course) until the ceiling junction is reached, and then it becomes roughly parabolic. For visualization purposes, I compare the area expansion at different distances from the apex with a rectangular horn having straight walls in the post called "Room Corner Characteristics." I use this feature in some of my designs, but it isn't particularly germane to this particular horn. The horn I'm looking at right now is a high-power horn that probably won't be used in homes and its main feature is the push-pull plenum prior to the throat.

Wayne