Linkwitz Pluto, available as either a turnkey product ($3K) or DIY (about $800 if you buy the plans and circuit board package from SL and stuff the boards yourself).
Speakers with uniform but more directivity sound as natural but suffer less from nearby objects and retain clarity farther into the room; but more directivity comes from things like dipoles (you dump a lot of displacement into the acoustic short circuit) or wave guides (which are harder to construct in small quantities).
Speakers with uniform but more directivity sound as natural but suffer less from nearby objects and retain clarity farther into the room; but more directivity comes from things like dipoles (you dump a lot of displacement into the acoustic short circuit) or wave guides (which are harder to construct in small quantities).