Originally Posted by cu_shane
So here are some pictures of the space where everything is going to go. The TV is going to go above the fireplace. The catch will be in front of the windows (directly across from the TV), but about 3' off of the wall. Eventually, we plan to put build-in shelving on either side of the fireplace, which would give me a great place to conceal my AVR, cable box, etc. As you can see on the floor plan in the OP, the room is 18' wide and 16' deep and you have two wide doorways on either side of the room. We'll add a large rug so that should help with the room acoustics.
If you're planning to place the TV above the fireplace (along the 18' long wall), try the following Main Listening Positions (MLPs) to minimize standing bass waves.
From the front wall = 0.32 x 18' = 5.76'
From the side wall = 0.32 x 16' = 5.12'
From the front wall = 0.45 x 18' = 8.1'
From the side wall = 0.45 x 16' = 7.2'
From the front wall = 0.55 x 18' = 9.9'
From the side wall = 0.55 x 16' = 8.8'
From the front wall = 0.68 x 18' = 12.24'
From the side wall = 0.68 x 16' = 10.88'
For correct stereo image, the left and right speakers need to be in an equilateral triangle to the MLP. Tweeters pointed pointed to the ears. If you're going with LCR arrangement, try to keep the maximum vertical displacement between the center and left + right speakers to be under 2'.
Position 1 is near field. Obviously the further away from the transducers, the higher the sensitivity needs to be to get the max value of 105dB. Position 4 might be a stretch with small satellites. A lot will depend on your Denon room eq results. Generally, like to see a negative number for the SPL levels.
For the sub placement, try out the front corners of the room first to excite all room modes. If this causes too much variation in the bass response at the MLP, try the following alternative sub locations along the 18' length wall: 4.5' & 13.5'. If this doesn't work, place the sub near the MLP. Later on and when funds are available, a 2nd sub will do a much better job of smoothing out the bass.
For your window, please consider using broadband sound absorption curtains/drapes, this will help reduce reflections from the back wall and improve the image from the front sound stage.
If you give me your ceiling height, I can post your room modes graphs.
Edit: Shane's listening room mode graph attached. Room volume is just over 2,300 cu. ft. The first mode is due to the ceiling of 71Hz. The width (31Hz) and length (35 Hz) modes are much lower.