Well that could be a positioning problem. You can try either moving the sub to a different location, or for less hastle, even turn it 90 degrees or something. Just something to give it a new position/orientation to see if your results change at all. Sometimes even a very slight adjustment (a couple inches) can make a noticable change in sound.

____________________________ M22 VP100 QS8 EP500 Yamaha HTR-5960