Room Treatment? How important is it to treat the wall behind/between the speakers?

@macg19,

Your equipment is very nice and room seems to have good capability. First thing I would do is to move your speaker at least 3 more feet into the room (if possible). Adjust the seat position to close to an equilateral triangle, keeping all vertices between the speakers and speakers and you the same. That will also improve direct sound from them vs room reflections. I use lots of diffusion in my room (all walls and ceiling). You can check the pictures of my room in my profile. They are not updated after my latest diffusers and bass traps inside the closet were added, but you'll have an idea. Best of luck, 

@macg19,

Glad to hear that :). Give them space to breath. You can always keep tweaking and also adjusting the toe-in to find the best compromise between the phantom center and lateral front soundstage.

For reference, the front plane of my speakers are now 77in from surface of the front wall, with 84in between tweeters and also 84in from the listening position, in a perfect triangle. Toe-in less than 10 degrees I cannot ever tell the sound is coming from the speakers, but will come from behind their plane all times and "extending" several feet behind the front diffuser as some of the recordings were made. Soundstage to left and right of speakers is more dependent on the mixing but sometimes extend up to 3 feet beyond their physical positions, like coming from outside the side walls of the room. 

@macg19,

You can see updated pictures of my room in my profile now.

Long story on how to deal with the window... First thing I did was to use REW real time analyzer data/graphs (using the MiniDSP calibrated mic) to see where the resonant points of the room were when I played  low frequencies that I would hear the clear "booms" from the listening position. Just play the tones you want and walk through the room with the mic and find them while you are using the RTA or a SPL meter calibrated with C curve (A curve will not tell you true response for bass). Room bass nodes were partially located in the 4 room corners walls, from floor to ceiling, but they were much more concentrated inside the back sides of the closet - almost up to15db higher than in the listening position. So, I started to investigate what type of bass absorber was the best for the buck and ended using the Acoustic Fields designs. Worked like a charm... I made them as big as I could to fit the available space of the closet without tearing it apart. To make it happen, I had to repurpose the fractal diffuser that was inside the closet and moved it to the right-side wall and the small one from the right wall I originally had I moved to the window side. I did not want to remove the window, so what I did was to use a technique they use in mixing studios where they use portable treatment to control their recordings. I build a pair of sawhorses and created a support for my small fractal diffuser.

The bass traps significantly improved the entire bass response of the room because I could better integrate the subs with the main speakers using crossover & volume adjustments while maintaining a better response of the bass. With the 4 bass absorbers in place, I was able to lower the response of the room around ~35Hz by about 6db. Repurposing the two fractals, I also eliminated the problem of the window, since I eliminated the first reflection problems from both speakers adjusting the position of the middle of the diffuser height to the listening position. Soundstage got more precise and expanded to the sides of both speakers.

You can use a mirror to find first reflection points. Just ask someone to hold it in the wall and move it until you see the mid driver/tweeter – just pay attention to which speaker you are seeing... That is the area where you need to treat for first reflections. Same is true for ceiling and floor.

Hope this helps answers your question.