Noise in my sub? Please help.

ok I have a higher pitched humming comming out of just my sub when ever my amp is on, also there is rumbling noise when i change tracks on the cd. and it gets worse when the car is running, when I unplug the rca cables the noise is gone. this is the weird part. I tried running cables straight from the battery thinking that my power/ground might be bad but still had the same problem. So I used the same cables from a different car(outside power sorce to power my amp) and the noise went away, sounds very clean and tight. I also tried different grounds and power for my head unit and still the same noise. Then i brought in a small battery and hooked up my pioneer head unit to it, and the noise stopped. Its like the amp and the head unit are interfearing with each other. I've seen that you can get rca noise filters that are to match the impeadence betwene the amp and head unit. Do you think that could be the problem, some kind of impeadence mismatch? Also if i put the amp in bridged mode the sub will flutter (a low sounding flutter) so i have to run it on only one channel? also tried a new amp and that does the same thing. Do you think there is something wrong with my head unit if so why do all my problems go away when i power my amp from an outside sorce?

There are varies things that you can try. Are your RCA and power cable run on opposite sides of the car? Lowering the gain on the sub from your head unit or the amp. Get better shielded rca cable. Isolate the amp from any metal body of the car. Check your speaker cable and see if they are touching any of the power wire. Be careful whose advice you buy, but be patient with those who supply it.

no my rca and power are run on the same side, but they have allways been on the same side and I never had noise before. just recently, would rca cables just go bad? and why does the noise go away when i hook up the amp to an outside sorce. what about a noise filter on the power or ground cables? I will try to get ahold of some new rca's and try that, ill post my results.

try moving the rca from the power lines and turn on and check to see if the are pushed in all the way at the head and amp and chech the gain

"why does the noise go away when i hook up the amp to an outside sorce." You are probably not getting any electrical interference on your RCA cable when you are hooking it up from an outside source. On the other, the RCA inside your car might since they are much closer to your power cable. Don’t spend your money on noise filter. Lots of people have bought them and ask me to put them in. I have yet seen one that works. Spend money on a well-shielded RCA cable instead of a noise filter. I have a lot of success on eliminating engine noise by doing two simple things. Run the power and RCA cable on the opposite side of the car. Second, find a big fat seatbelt bolt or some sort for a good ground. Be careful whose advice you buy, but be patient with those who supply it.

when i say outside sorce I am not talking about the rca's. I hooked up the power and ground on the amp) with jumper cables to a different car and the noise went away.??? so if its the rca's for some reason they dont pick up the interfearence when the amp has outside power,

"so if its the rca's for some reason they dont pick up the interfearence when the amp has outside power, " In this case, run your RCA on the opposite side of your power cable and it should solve your problem.Be careful whose advice you buy, but be patient with those who supply it.