Why can't my subwoofer properly play back super-low sub bass tones?

I have a $200 polk subwoofer hooked up to a modern Onkyo receiver autoconfigured with that Audyssey MultEQ or whatever blabla stuff. However, when my system plays songs with maybe 30-50 hz sweeps, the subwoofer goes off the deep end and starts clicking and it overall fails to properly reproduce these sounds. What's wrong? I think it has something to do with whatever those things are called low pass filter? I'm sure my expensive sub can play low bass right but something's janked up with the settings