My question will be about the Atlantic Technology 452 PBM Sub THX.(PDF below)

http://www.atlantictechnology.com/Upload/PDFs/manuals/discontinued/452PBM_manual.pdf

My receiver is the Yamaha RX3800, the problem I'll mention was also one I had with my Denon 3803. I currently have a new Sub cable, replacing my old Sub cable. Cable goes to Low Level in on the Sub, comes from the proper section on the Yammy. I've tried the settings of 80 and 100 on the sub, and in the Yammy's settings.(Matching each time) All speakers are set to large in my system 450TXH because that is what is suggested paired with the Toshiba XA2.

Currently, I need to set my front Bass Level knob on the sub in the 10% range, 15% range max. Anything over that, the sub gets a nasty rattle type sound vibration. I know subs boom, but this is a rattle that sounds very bad. This sub did have a small slice/cut in the front cone and I thought that was it. I just ordered the new entire front and replaced it thinking that would fix it. That was not the answer. I have it set at 0db in the Yammy's settings, and I've moved that up and down. No help there.

With the sub level in the 10% to 15% range, I do not get thump with my movies. I can turn it up to the 40% range or greater and it sounds great, but that vibration is included and sounds horrible. I want my punch, I want to be at 40%, but I can't even get close because of this rattle.

Everything is on tight, there are no parts that may be loose. Any thoughts on what might be going on?

Are you sure that there is not something loose inside the sub? That is what it sounds like to me.

Well, it sounds like the vibration/static comes from the cone itself.(Maybe the correct term is distortion looking at the sub's manual??) Regardless, I looked around when I replaced the woofer/cone and it was nothing but cotton inside. I guess if I pulled all that out, I could get to the back of the unit where the power is. But the rattle is right up front, sorta in the center of the cone.

Probably a blown driver.
Try pushing the cone in when there is nothing being played through it. If you hear a scratching noise or rough resistance, you have a bad driver.

I think the driver is part of what I just replaced, correct? It was $130 for the part. It was the cone all the way back through the magnets. The thing I replaced was about 8 or 9 inches from the front cone to the back of the magnets.(About 20 to 30lbs??) The only thing behind this 8" deep thing I replaced is about 12 inches of cotton then all the electronics on the back wall. I'm thinking my driver was replaced when I put a new cone on, only way I could get it from AT.