Thanks for the insights Steve. I haven't noted much "boom" down low, as the room resonances higher up in the mid-bass (say around 160-180Hz) are more prominent. I'm intrigued with the actual result of the corner loading continuing the horn flare particularly when the output is from a split 2-section horn and is augmented from the front-firing woofer. Frankly the physics and audio math necessary to figure out how this horn actually performs is beyond me, though Figure 2. in the PDF I posted in post #28 does show the interference effect you have mentioned around the flare cutoff.
If Jensen is specifying the flare cutoff at 43Hz (which has a wavelength of around 26'), I think this must be using the additional flare of the room walls?
Almost as if the entire cabinet is a loading chamber feeding the throat of a 1/2 horn formed by the room corner? I say 1/2 as the top of the horn is open with only the sides and bottom in place (walls and floor). Though I may be way off base (bass...
) here as I don't know how much loading a horn has when one of the 4 walls is absent? However, the Klipschorn seems to work this way. I'm interested in your thoughts on the audio physics of this, since once you are out into the room or in another room, one has the impression of the whole room loading the driver. I recall as a child that my father was playing around one day and cranked the system up full with pipe organ music...he cracked open a window in our den and closed the door to the room before he stepped out into the street. I could have sworn the pipe organ was the whole house as a loading chamber playing for the outside world.