Terrific interview by Matthew! These DT guys are getting scarily close to some right answers about loudspeaker design. Just a few corrections, or hints, to all of them, including Philip Jones:
1. Most of the pictures in the article show the speakers either positioned wrong or aimed wrong. It looks like they have them too close to the front wall and aimed straight fore/aft. They need to be 1/4 of the room width in from the side walls and the same distance out from the front wall. This will provide perfectly even spacing among all real and virtual (reflected) speakers. Then they need to be aimed 30° inward toward the listeners to get more correct angles for time/ intensity trading for a stable center and more importantly to strengthen the corner secondary reflections that bounce off the front and then side walls and come out as deep and wide as possible. I have tried to send DT an email on this, with a Powerpoint set of pictures that show why their owner manual recommendations are wrong.
2. I'm glad they have discovered the bipole radiation with adjustable pattern, but they still have it backwards. You need about 6 dB greater gain from the rear than the front, because the reflected sound has to travel twice as far as the direct.
It is NOT correct that the reflected sound messes up imaging! The early reflected sound focuses too, if you just know how to position speakers and/or make a drawing of the image model of the total horizontal pattern of direct and reflected sound that you are hearing.