Hi, new to the forum. I've always used AVS whenever researching home audio equipment or had general. audio questions, so I'm glad I finally joined the forum. Within the last few months, I've finally upgraded my equipment from a Sony htib. The difference is night and day and I've found a new hobby that I really enjoy. Although recently purchasing my first home and having a second baby due soon, I can't go as crazy as I'd like. Anyways, my question is regarding subwoofer rumble, and it's totally a newbie question. In the last two weeks, I've upgraded my subwoofer from a cheap 10" Sony, to a Polk PSW110, to finally a Bic America F12. Neither the Sony or the Polk rumbled like the Bic and I'm wondering what's causing it. It just gets a little annoying during deep bass scenes when the subwoofer itself is making noise. I may be expecting too much out of it, but neither of my previous subs did it. I know it's not anything around the sub vibrating, it's the actual subwoofer. I know it's not the floor neither, I've held the sub in the air and it still does it. Also, I've shaken the sub and it doesn't sound like anything is loose in there. Each subwoofer was calibrated to 75db so I don't believe that it's happening because it's simply louder. Can it be the fact that the bic can get deeper but at the same time not handle it too well? If that is the case, I'd rather have a sub with less extension but can handle itself. Any feedback would be awesome, and I apologize ahead of time for such an amateur question.