To all respondents–room is 21′ wide and 19′ deep.. Ceiling height starts at 6.5′ at front wall, rises to c. 12′ above listening position, and then descends fairly quickly to 8′-high backwall.. The main, 16″-high, left-right beam near the front of the room is centered about 4′ from the front wall, and most speakers have been placed, over the almost-43 years I’ve had this room, with their faces 5 to 5-1/2′ from the front wall.. Listening position is c. 3′ from rear wall.. The room has a relatively low proportion of its flat surfaces parallel with other flat surfaces, and all walls are rather diffuse from all the cabinets, etc. around the room.
I’ve added two LARGE basstraps on the left and the rear wall, both being about 1.5×2.5′ rectangals maybe 10′ long and containing NO reflective plastic; these plus two 3’x 6’x 6″ panels on the front room absorb lots of broadband acoustic energy.. Due to its almost-square nature, the room has a bass node at c. 30Hz that’s VERY strong and peaky and substantially reduced by the basstraps.
I sit about 10′ away from the faces of the speakers, and the faces of my current speakers, the very excellent Vandersteen 7.2s, are centered about 9.5 feet apart.
I plan to get to SanDiego this Saturday to hear a pair of SLs.