Question about reflex duct shape

[Bigun]

using a tapered port is one way to avoid resonances in the port. I designed my port to taper so that the larger opening was on the outside. I figure it's going to do a better job coupling the sound to air, like a BVR.

my design accomplished this with a triangular port spacer:


http://www.diyaudio.com/forums/full-range/175056-martello-enclosure-fr88ex.html#post2327342