More horn madness

Some horns get wider in a graceful way (to meet up with any 2pi woofer). At these lower mid frequencies the diffraction may be less of a direct issue. But understand that if you have diffraction, you also have modes that can affect response/power. These variations are still an issue.

For the same reason, unintended variations in directivity can be behind troublesome response issues.
 
@Pano and Allen,
Yes, there are some issues as usual! But these are not so difficult to live with as a "normal" two way speaker.
Anyway, I'm going to explore a coaxial driver as soon as I can visit Italy again. Hopefully, Sica has not turned belly up in two weeks...