Need to know if my new subwoofer is defective

I got the Onkyo HT540 7.1 surround system. The speakers sound fine. Inside the hole of the subwoofer is this what looks like a cardboard tube that just sits inside the hole freely and is not connected to anything. I can grab it and lift it but not connect it to anything or take it out. Now when listening to anything it sounds like the crossover is too low. Certain sounds that I expect to come from base do not play on base but play on the speakers., only deep base seems to come out of the sub. My current receiver is old and has no crossover setting, however my previous sony sub was very loud and never had this problem. Of course that sub had a crossover dial but the sub is broken. Just wondering if the sub might be defective, especially because of what seems like a broken piece.

the speakers and sub seem large to me, but i always have been a budget av person. cnet says they might be too large for some people