Post a picture of your room and we can really give better advise.
The front wall may need a combination of absorbers in the corner and diffusers in the middle.
Just look at your wall and how much black space you have back there. Flat walls are the enemy.
The space behind the absorber should be about equal to the thickness.
Porous material is best to work well with a wider frequency range. Painted canvas will work well too but better in a mid frequency range.
Here are the pictures of my listening room. The room is about 15x22. The recliner will be taken out when I get my speakers complete. My NX-otica's will be on each side of the TV stand about 3 to 4 feet out. I have that slanted ceiling on one side not sure what that will do to the sound. I have about 3.5 ft of empty space between the back wall and couch.
Front of the room.
Not exactly sure what I need to put on this wall.
Left side of room
Right side of room. I am going to put some sound absorbing art above the fireplace and maybe above the curtains. There are double doors behind each set of curtains.
I am wanting something to put on the back wall to disperse. Maybe a large book shelf.
Although this room is not perfect I feel like I have a really good area to work with.
