A friend of mine wanted to do some recording in his Mancave, and a friend/engineer came up with this setup, using Reaper... the "jam" room is on the other side of the glass...
The back wall however wasn't that far behind (ten feet ) and reflective, so the engineer asked me to build a baffle similar to what was in a studio in Arizona he worked at. Notice the pattern on the slats to break up and absorb frequencies... works well. It's hung on the wall with a 2x4 sawn in half at a 45-degree angle, with one piece attached to the baffle, and the other secured to the wall, with foam between the two "faces", so the baffle doesn't touch the wall. (Large and heavy paintings are hung using the 45-degree "rails", and one just slides down on to the other... ) Foam was also attached to the bottom of the frame so the baffle doesn't physically touch the wall at all. Beneath the material is 2-inch hard fiberglass panels. If I remember correctly, it's 4-feet tall, 7-feet wide, and 4/5-inches deep. I think total labor was ten hours-or-so....
So that's the secret to a pro recording: 25,000 pounds of sand! I guess it's off to Toys R Us to purchase play sand now. Can't wait to pump it into my walls, only to accidentally puncture my sheetrock with a mic stand and find myself buried alive! 
