Interesting article Marc. It essentially comes down to if you ignore room boundaries you may get different response based upon the orientation of the driver array (as opposed to dispersion specific to a driver). This will provide a good starting point for playing with my room config. As the...
Why do you need to keep the M22 vertical when run as a center? Is this due to the dispersion characteristic of the tweeter? I understand why things change when you get close to room boundaries, but I do not understand why the orientation affects things (assuming height etc remain constant). .