If you go to the audioperfectionist.com website and download the free journals, there is a very good describtion of how the author treated his living room. I have been to his house and you can't see the treatments. Looks like any living room. It also had the best acoustics of any listening room I have ever heard outside of a dedicated music room.
In brief, he took 2x2s and attached them horizontally along the middle of his walls, dividing the walls into two 4 foot high sections. Then 2x2s every 2 feet vertically. That divides the walls into 2foot x 4foot sections. Inbetween each section he placed 2x4 solid insulation from Corning, up to the first and second reflection point. From there back he left the spaces empty, although, I think you could continue the insulation and then cover it with something reflective like thick plastic sheeting or thin wood paneling if you didn't want the empty spaces. Then he stretched fabric, horizontally, over the whole wall , stapleing it to the 2x2s. Finally, he put molding all along the outside edges and one chair rail down the middle strip to hide the seams and staples. You would never know that the room had been treated, it simply looks like expensive cloth wallpaper. You could even use two types of cloth, one below the chair rail and one above.
The only commercial treatment he has is two ASCtube bass traps in the back corners.
In brief, he took 2x2s and attached them horizontally along the middle of his walls, dividing the walls into two 4 foot high sections. Then 2x2s every 2 feet vertically. That divides the walls into 2foot x 4foot sections. Inbetween each section he placed 2x4 solid insulation from Corning, up to the first and second reflection point. From there back he left the spaces empty, although, I think you could continue the insulation and then cover it with something reflective like thick plastic sheeting or thin wood paneling if you didn't want the empty spaces. Then he stretched fabric, horizontally, over the whole wall , stapleing it to the 2x2s. Finally, he put molding all along the outside edges and one chair rail down the middle strip to hide the seams and staples. You would never know that the room had been treated, it simply looks like expensive cloth wallpaper. You could even use two types of cloth, one below the chair rail and one above.
The only commercial treatment he has is two ASCtube bass traps in the back corners.