I was reading another post regarding subwoofer drop off at certain frequencies. I am not completely sure what that is, but I wanted to test my subwoofer. I put on "Shake Rattle and Roll" from my Chesky test disc. What it does is play a tone starting at a frequency of 300 and goes down gradually over a period 2.5 minutes to 20. Using my sound meter, I observed the decibel level as the pitch went down. I was expecting the decibel level to stay about the same. For most of it, it stayed at around 90 Db (+/- 7 or so). At about 50, it started to drop off. It went to about 80 Db. Then at about 30 it dropped pretty fast to about 60 Db by the time it reached a frequency of 20. Is this normal for a Rava subwoofer?