Try the corner of the room. That is where I get the best response and I got the idea from M&K sub manual. I tried it on Creative S750 computer speaker sub.http://www.mksound.com/pdf/user_manu...5000_mx350.pdf
A simple rule to remember is that you get more bass when you move the subwoofer towards any wall or corner. Moving it away from a wall or corner gives you less bass. Remember that the floor also loads the subwoofer, and that maximum bass is found with the woofer on the floor in a corner.
We recommend starting with the woofer in a corner (or very close to one), and proceeding from there. Extensive MLSSA measurements have shown corner locations to be most likely to give the best overall bass response. A corner location will give you maximum bass output and sonic excitement,
as well as a standard to compare with if you move the subwoofer around.
In some rooms, corner locations excite resonance modes, producing a "muddy" or "boomy" sound. In these rooms, a location along a wall, away from the corner, may give the best results. Find a spot where no single bass note overpowers the others and the overall sound is powerful and clean. You want to achieve a smooth sound quality, with the entire bass spectrum equally prominent. Usually, this will be along one wall, close to or directly in a corner, not in the center of the room.