well, when you treat a room you treat it for acoustical pressure (bass) &/or for acoustical waves (mid/highs). When you are treating the acoustical waves you'll find that the treatment is rarely slammed against the wall - there's almost always an air gap. That's because when the acoustical wave hits the wall it stops. Thus, No use having the acoustical wave treatment against the wall when the wave has already stopped!
when you are treating bass the treatment is often in the corner 'cuz bass waves reinforce in the corner. Bass traps are almost always slammed against the wall. And, since you are treating acoustical pressure you need to have suitable material inside the treatment that absorbs bass freq (20-400Hz). The burlap outside is just for cosmetic purposes. I've also found that you need a lot of material to absorb bass effectively as opposed to a 2" or 4" panel to absorb mids/highs.
Not sure why the Real Traps work better for bass absorption with air behind them?? does not make too much sense to me. Maybe they are trying to absorb lower mid freq as well?
when you are treating bass the treatment is often in the corner 'cuz bass waves reinforce in the corner. Bass traps are almost always slammed against the wall. And, since you are treating acoustical pressure you need to have suitable material inside the treatment that absorbs bass freq (20-400Hz). The burlap outside is just for cosmetic purposes. I've also found that you need a lot of material to absorb bass effectively as opposed to a 2" or 4" panel to absorb mids/highs.
Not sure why the Real Traps work better for bass absorption with air behind them?? does not make too much sense to me. Maybe they are trying to absorb lower mid freq as well?