How much did you open it, Mine isn't very open. I think it just bounces it out the back at the wall then around you. Worked quite well in a 15x14 room. It takes some of the bass sounds like 5 - 10% if you have someone open and close it while your playing. It sounds less muddy/muffled out, not a lot, the most noticeable thing was that the sound fills the room with a wider soundstage. I have velcro stuck to the back panel from when I tried adding some batting, didn't change the characteristics of the closed box much at all.