Subs...ugh

Ive already posted this in the audio section, but I know that some of you guys know stereos too, so here it is....

In my civic, I have two mtx 6000 series 12" subs powered by a kenwood 1000 watt amp. One of my subs is grounded out, so I have it completely disconnected. The one sub I do have connected is bridged. My question is this: When I start my car, and my stereo turns on, my amp comes on, and immediately, my subs have a whine first of all, but thats more in the background. The sub also has a rumble in it, and it goes according to my rpm's, up to about 2000 rpm's. Then it dies off. I can really only hear it at low volume levels, however, it stays the same, like if I have it on volume 1, it will be as loud as if I had it on volume 50, I just wouldnt be able to hear it since everything else would be so loud. What is causing it to make all this noise? Is it not grounded right or is something else wrong...my amp...wiring...rc cables...etc? I need help, and this is the only place I knew to come.

Sounds like a ground loop to me... make sure your amp is grounded good to the body... with as large guage wire as you can (no smaller the 8 guage.... I'd reccomend at least 4guage)... and try to keep the ground cable under a foot long.

I know my ground cable is 4 guage, and its about a foot and a half, and where its positioned, it goes right to my strut tower in the rear, so I have it fastened under a bolt that goes to my body. I can go check to see if its alright, but I know that another place in my trunk works great for grounding, but its a good 2 1/2 feet away from my amp. Why is it bad to have a long ground?

the shorter the cable, the quicker the electric loop can ground out and not feed back up through the cable to the amp causing the ground loop.... the longer the cable is, the more distance the current has to feed back up through the cable...

it's like a microphone... if you have a speaker in front of a mic it's hooked to, you get a feed back loop... but the further the distance you place it away (or in a sense, the closer the larger area is to the mic) the less problem you have with a loop...

Okay, thanks for the info, I went out and it looks like my ground might not be getting a great connection to my body, and it has a connecter on the end of it that like comes to a circle,(im sorry, I have no idea what those are called) but yeah, the circle is too small to fit flush against the bolt. Should I cut off the circle thing and just attacj the ground cable wire itself to the body and by way of the bolt, or should I just try to get a better connection with what I have?

Just drill you a hole in the floor pan of the trunk, sand the area down, put a bolt through there and tighten down real good... put some silicone calking around the hole and the bolt to prevent rust.

Alright thanks man, I'm going to do that at work tomorrow, thanks for all your help.