More on the subject of comb filtering.
I guess I haven't hung around enough to see what everyone is doing
Very cool danny
I recall the Tekton Enzo, with a three tweeter line array, measured pretty well by Stereophile. Even though it is a 2.5 way with ten inch woofers the mids looked decent.
They do not work like a line source. A line source needs all the drive units to be center to center within the wave length of the lowest freq prominently produced . And, they should be as tall as the room to create a "line source" type wave front. Of course, there are watered down versions of this that have some success. Tekton (say the Impact) uses attenuation and outright phase rotation to blend the array. Rather clever.
I think for the most part, danny is talking about speakers like these: