@mijostyn "you need to learn more about speaker design. The foot comes from the wavelength at the crossover point. ... What you are succumbing to is lay assumption and as we all know assumptions are the mother of all f-ups"
So now I know that the "foot" comes from your assumption about the cross-over frequency - some mother of an assumption, especially with 3-way speakers which have two crossover frequencies!
Your next statement is equally flawed "If two drivers are closer together than 1/2 the wavelength at the crossover frequency they function acoustically as one drive".
This proposition fails when reduced to absurdity. Imagine the two drivers are omnidirectional and 1/2 wavelength apart.. Then along the line of the drivers, there is complete cancellation! And on any other position, except equidistance, there is some cancellation. Hardly functioning as one driver.
From memory you have made equally odd claims. One is that only the sound from the closest point of your Sound Labs reaches your ear. Well, if that were true, you could just keep an horizontal inch or so of the panel, and ditch the rest. (See the reciprocity principle below). The idea behind your assertion probably comes from that White Peper which describes the radiation pattern like the bristles from a bottle brush, entirely in the horizontal plane.
But that is not true either. If it was, there would be no radiation to reflect from the ceiling and floor, and no need for the speaker to reach either!
The White Paper makes a big thing of an "acoustical principle that we refer to as microphone/speaker reciprocity". I would not dignify it by calling it a principle, but it makes the case that speakers should be positioned as far apart as the (two!) microphones were, and the incoming (microphone) and outgoing (speaker) radiation patterns should match. The aim is that walking around the listening room should give the same experience as walking round the recording venue.
Why then, does this principle not also dictate that the speaker should be positioned at the same height as the recording microphone, and approximate it in vertical dimension? I don't like so-called principles where you pick and choose what applies.
Walk round a concert hall (unpopular with the rest of the audience) and you will find sound coming from every direction. Elsewhere I believe you have said the soundstage should be entirely between the speakers, and anything else is because wall reflections have not been eliminated. Get real, decent systems can, and should, throw a soundstage extending far beyond the speakers, because that mimics the original venue.
"Quad was trying to improve dispersion. Stick with your KEFs"
Seems as if you are unfamiliar with the ESL-63 and later Quads? Quad deliberately reduced the treble dispersion to "improve" it.
