Alternator whine out of speakers - I've trouble shooted, need your help?

[XPerties 10+ year member]

So normally I chill over at some f150 forums but I think this issue is for the experts, you guys. So here is my post I made over there and then some follow up on some testing I did. Your help is much needed and very very much appreciated.

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I've done a lot of searching on the forums for the last 2 days and have trouble shooted this issue and can't figure it out. I have a whine come from my front and rear speakers which are hooked up to my rockford amp. I never had this issue until:

[1] I added a sony amp to run my memphis 12 sub

[2] Added a second set of RCA cables

The rockford use to run front components on 2 channel and the other 2 channel ran my sub. Now I added the other amp (sony) for my sub. I first grounded to my seat bolt in the rear but found that was a bad spot (per forums) so I found a post that said:

1) Get a length of 8 or 6 AWG long enough to reach the battery (as an "extended lead") and check resistance of said wire with a DMM. Remember this number as it will be important to you very soon.
2) Attach the "extended lead" to the negative terminal on the battery. Now touch one lead of your DMM to the proposed ground and the other to the end of your 8AWG. Subtract that number from step one and that is your total resistance. If its a good ground it will be less than 1 ohm.

So I did that and found a nice ground for both amps that was around .2-.5. Whine noise still there so I found a post about HU ground and never using factory ground so I ran 2 grounds from the bottom right hand panel to the HU. One ground went to wire harness and the other went to the back of the heatsink (per manual suggested to do this. The HU is a Alpine FYI.

I have the hot wire from the battery running up the passenger side door seal and 3 RCA cables and remote wire running under carpet up the center of the truck to the back where both amps are installed on back wall, mounted on 1/2 MDF.

Is it possible to have a bad set of new RCA cables?

Running remote with RCA cables bad or would that cause this issue?

Running RCA cables together bad?

Your input is much appreciated.

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So I read on some google search, forums post that you can hook your ipod up to your amp and if you don't have the whine anymore then it's RCA and back to your HU.

I did this and it sounded perfect. I then grabbed a good home audio pair of RCA and ran a jump test from my head unit to the amp. I unplugged all RCA's that are ran under my carpet and used the home audio cables and I still got the whine.

I think tomorrow I'm going to rip the HU out and rewire it as if I was putting it in for the first time (been in my truck for over a year). Any ideas on the issue pertaining to the HU and how to fix?

Someone said it's probably my, as they called it "crap sony amp" and I followed up with this reply:

Sony amp is not in play as I said in my prior post. In fact the sony amp is powering my sub and has no whining. The whining is coming from my door speakers which is powered by the rockford amp. With sony turned off and completely disconnected I still get the noise.
With the RCA cables unplugged, sony amp turned off and source of music coming directly from my ipod it sounds perfect. Plug the RCA back in and noise returns. Unplug all RCA that are ran under carpet and use a spare pair and do a direct jump from head unit to amp and noise is back.

It seems I have pinned it down to the HU being the source of the whining. I have ran 2 grounds (1 from heatsink and 1 from HU black ground) to a permanent ground to the foot floorboard. I also tried the trick and wrapped a ground wire around the outside of the rca plugs and then plugged the RCA's in and that didn't work.

HU power source: could this cause a major alternator whine?

I know it's a lot of reading but I try to give as much information as I possible can.

Click to read more...

 

[DammitJames 10+ year member]

well what i got out of that is that you put your ipod direct to the amp and the whine goes away? so that eliminates the amp ground which is one of the major causes of it next is where is your rcas ran? are they next to your power cable?

 

[randpost 10+ year member]

I have my RCA's ran on one side of the car and my power on the other side. I also had alternator whine through my speakers. this occurred due to the fact that i had my RCA cables laying beside my power cables near the amp ( only near the amp). After I secured my wires near the amp so that the RCA cables and the power cable were as far apart as possible (while still being connected to the amp), the alternator whine was eliminated.

This might not solve your issue, but I went through what you did, and this was the only cure to my WHINE.

 

[michaellane 5,000+ posts]

your rca's are too close to the power wire somewhere near the amp. try moving them around a little. or right behind the radio cover them with electrical tape for a few feet and the same near the amp. see if that helps.

 

[XPerties 10+ year member]

I don't think it's the RCA. I have the RCA ran under my carpet directly down the center of the truck and power ran down the passenger side door seal HOWEVER as a test I grabbed a new pair of high end RCA and plugged them in to the HU and held them in my hand as they jumped right to the amp and the whining noise was there. The RCA weren't close to anything.

I'm not using the factory ground on the HU, as a matter of fact I have 2 ground (1 from heatsink and 1 from wire harness) that goes to a perfect ground. Would using the factory power wire cause this?

Should I maybe run a power source directly to the positive terminal of the battery?