A couple of months ago I bought the Velodyne Deco surround sound system. Everything is great about it, except for one thing. When im playing a dvd, if there is just voice (no music, little or no background noise), the sub will "thump" as the person is speaking. Its a low frequency thump thats not very loud at all, but its noticeable to my ear. Whats strange is that it seems to only get worse when I lower the crossover to allow only the lowest frequencys.

Im guessing it might be some settings on my receiver (Pioneer 509S), but I just wanted to know if anyone else has had this problem and what troubleshooting ideas everyone might have. Thanks...