Bad feedback from rear speakers/subs/amp!!

[jbwilliam]

My buddy has a Pontiac Bonneville and i figured id just post here instead of searching for a forum signing up for one and asking someone on a Pontiac forum. My buddy bought about 1g worth of audio equipment and we hooked it all up about 8 months ago. EVERYTHING HAS WORKED FINE ALWAYS. No problems whatsoever. About 2 months ago we installed interior neon lights. Hooked them to the 12v from the amp to the head unit and just wired it in. NO PROBLEM! Worked fine for two months and today he was driving down to my house and this bad feedback started happening out of know where. Now the weird thing is the volume will be all the way down and it will still happen, also when he revs his engine and the alternator charges more the sound changes pitches and gets louder. Took a video of the sound to see if anyone knows anything. Also when I turn off the interior lights the sound fades less but I think its just because its not using as much power. Idk lemmie know your thoughts! We have disconnected the power line to the amp and tried again and have disconnected the neon lights and rewired the amp 12v together and the sound still happens. Lemmie know your thoughts!

heres the video!
http://yfrog.com/2himg0134z

 

[xWIREMANx]

Is that a 5 channel amp? What do you mean you hooked them up to the 12v from the amp to the head unit? Do you mean the blue remote wire? If you hooke them up to the remote wire then disconnect them from there. That is a low current remote wire and can't run them by itself. You could use the remote wire to turn on a relay from a more powerfull source if you want them switched with the deck like that. If you used the remote wire from the deck you may also have damaged the headunit as well. Does the sound go away when you disconnect the RCA's? You may be getting noise injected into the RCA's by having them run too close to power whether it be your amp power or just power in the car. You could check the ground of the amp to make sure it is tight and to clean metal (not painted). No alternator noise should come through the sub when the amp is on low pass. If you are running your highs on that amp then make sure your RCA's are running down the opposite side of the car as the power cable. Prefferably RCA's down passenger side and power down drivers side. If you ever have to cross the two then it should cross in an x pattern and not side by side. They also make ground loop isolators for RCA's as a last resort or filters for the power line on the deck in case it is coming from there. Use the process of elimination method to find the source first. Unplug RCA's at amp. If noise stays then something is wrong at the amp. If noise goes away then plug them back into the amp and unplug at deck. If noise goes away then it is coming from the deck if noise stays then it is coming from noise being injected into the RCA's. There are other things to check such as grounds in the engine bay, power connections at the battery and alternator. Is the battery staying charged? Could be a damaged alternator as well. Hope that helps find your problem.

 

[lethal6]

Ugh! Alternator whine. One of the biggest pains in the a$$ to deal with when doing stereo installs. Most of the major points were covered above so I won't restate them. There are a couple "bandaids" that you could buy (loop isolators, etc) but it is better if you can hone in on the problem and nip it at the bud.

My best guess would be that the power wire from the lights is leeching into the rca wires. Try running them on the opposite side of the car.