I used 1" x 1" wood to build a large frame in which I placed 1" duct board by using thick duct tape. This duct board is available at your local contractor supply housein 4' x 10' sheets for about $25. It is foil backed and has 1" of compressed insulation.
You can then cover the frame with your choice of acoustically transparent material. I haven't gotten around to covering mine. It does an amazing job at sound absorption. I don't use it often, but for my most serious listening, I put this in front of the TV. It covers the whole TV (I have a 57" Toshiba widescreen.) It stops alot of early reflections of the sound energy coming off the back and sides of my speakers. It helps to lock in the soundstage. When you are not using it, you can lean it against a wall or take it to the garage, etc.
You can then cover the frame with your choice of acoustically transparent material. I haven't gotten around to covering mine. It does an amazing job at sound absorption. I don't use it often, but for my most serious listening, I put this in front of the TV. It covers the whole TV (I have a 57" Toshiba widescreen.) It stops alot of early reflections of the sound energy coming off the back and sides of my speakers. It helps to lock in the soundstage. When you are not using it, you can lean it against a wall or take it to the garage, etc.