Is There Something Wrong With My Sub?

[horror4life245]

Hey Everyone,

I've had this new surround system for around a week and a half. The only thing is that the front speakers and the subwoofer are pretty old, about 7 years old or so. They were given to me by my older brother. The front speakers are MONSTERS and are loud and clear. They're Energy Connoisseur C-2. And I have a MartinLogan Encore TF Center Speaker, which is loud as hell, as well. The subwoofer is an Energy XL-S8. As of now the knobs are the low pass filter, which is at 75 out of 100. Then there is the bass volume, which is at 7 out of 10. No matter what movie I play, I only get the slightest whisper from the subwoofer.
I've tried movies such as King Kong (2005) (T-Rex Scene), SAW V (Pendulum Scene), and SAW VI (Ending scene with the theme, which I know has bass).
I've even tried music and it still comes out VERY soft and I can barely notice it. I get all the rumble from the front speakers, but I want a lot more from my subwoofer. I even did the auto-calibration with my Denon 1910 twice to see maybe if it just had something to do with that, and it didn't. The thing I KNOW isn't blown, because when I unplug the subwoofer, it makes a LOUD noise. However, when I do the auto-calibration and it makes the thudding noise, it's very small. This subwoofer has been known to be loud and to give a lot of rumble, but it isn't doing that. Is there anything I can do to improve the sub? It was originally on a desk and sounded bad and I just put in the floor and tested and it didn't sound any different. What do I do? Is there something wrong I'm doing? Please let me know so I can fix it and enjoy the bass parts of my movies, and hear it as loud as it is with my front and center speakers.

Also, is there maybe a way to make it on the receiver so it sends louder signals to the subwoofer? Please help!