If you get something like the Avia Guide To Home Theatre disc, there is a subwoofer calibration chapter that goes through a frequency sweep ... I found a rattle on a panel of the back of the TV at 43hz. Fortunately I was able to nip that little problem in the bud with a folded piece of heavy duty (high-tech anti-rattle) paper. Nobody looks behind the TV, right!

Rick
Our Room

smile