DUNLAVY SC-VI

What do you mean by a room build?

A good friend had Duntech Princess (more similar to DAL SC-IV) in a 20x20 room with a 9' vaulted ceiling and they sounded fantastic.

HOWEVER, read any source on acoustic design and they all recommend against a square room (avoid standing wave reinforcement). I think my friend's room worked so well only because one end has a 6' wide opening into a smaller room plus an open door way leading to another room; in other words his room was not square acoustically.

I would suggest contacting Rives Audio or other acoustical designers to discuss your situation. And I will suggest that all Dunlavy designed speakers work best with placement well out from both the front and sidewalls. I would be more concerned with sidewall distance than distance between speakers (meaning 4-4.5' each side with 10-12' between speakers [centerline to centerline] in a 20' room). In my experience the 10-11 feet to the listening chair that Daverz suggested will be the minimal distance. Such tall speakers need distance for the drivers to converge, particularly time/phase coherent designs like the DAL.

Room build means that I am purpose building a room for audio listening. Everything will be acoustically optimized including room treatments. Audio processors make me cringe even though they can be very effective. I think I have the width thing down pat, I am more concerned about low ceilings. 9 foot at the front wall and 6 foot at the back. 7.5 foot ceiling height 10 feet from the front wall. This means if they are 2 feet from the front wall, listening position should have a 7 foot ceiling height roughly. Perhaps I should place the speakers at the short wall facing the other way ?

I think you want the speakers firing away from the short ceiling side so that reflections are not "focused" on the listener by the ceiling, but I don't have any empirical acoustical data to back that up.

Alissatweaks, That's what I thought. With that in mind, is there a reason the room is 20' X 20'? Doubling dimensions is usually not the best way to go. I don't share your disdain for audio processors, and with those dimensions, such a piece of equipment might be helpful. I agree with Daverz that firing the speakers from the short ceiling side might be preferable, with that in mind the Dunlavy SC VI's height might be an issue.