Alternator Whine / Ground Loop help..

[AndrewH05]

Hello everyone.. I'm new here but have been reading through the forums for awhile now, I'm in need of some advice / help / opinions, I'm just going to copy / paste what I posted on another forum but unfortunately I was unable to get any help there so hopefully I'll have better luck here! Thanks in advance!

As far as amps are concerned I have a 4 channel amp for the interior speakers and a 2 channel amp for the subwoofers.

So this past weekend a friend and I spent 13 hours installing front / rear speakers, subs, 2 amps etc. etc. By the time we got done it was after 2 am so I didn't really get a chance to tune / listen on the way home, the next day I start my car and as I accelerate I hear the alternator whine. Now we spent extra time on the grounding, making sure it was good, the only mistake I believe I made is using the ground / power from the wiring harness. What makes me believe that it's not from any of the equipment I installed is because before I installed anything every time I would have my GPS and/or cell phone plugged into the cigarette lighter charging the radio station would go to total static. And that still happens even with the new Alpine HU and on top of that the alternator whine, which I didn't have with the stock speakers and HU. So since I believe my power and grounds are good, other than using the wiring harness this is what I plan to do:
The big 3 with 0 gauge wire, basically to re ground the electrical system, I'm going to go Battery > Engine Block > Chassis

Check radio antenna, is it possible for an antenna to 'go bad' and need replacing?

Wire power and ground from HU straight to battery, what size fuse should I use for the HU wiring to the battery? Should fuse both power/ground?

So my question basically is, is there anything else I should do while I'm doing the rest of this stuff? I'm really trying to avoid using ground loop isolators on the RCAs. Should I also ground the RCAs?

Thanks for all your help!

Update #1

Well, I figured out the radio static problem, apparently the connector came loose and fell out of the antenna. After reconnecting it the radio comes in crystal clear and the HD Radio feature works flawlessly.
After looking in the engine compartment, I noticed the main ground from the battery is grounded on an engine mount that is quite corroded so I'm looking for 0/1 gauge wire locally and will be doing the big 3 in hopes that will solve my problem before ripping out the dash again and running new power / ground wires for the head unit. What should I fuse my 105 amp alternator at? 120 amp fuse is the closest I believe..

Update #2

OKAY, so after some more testing these are the results:
1. I disconnected both sets of RCAs from the 4 channel amplifier, started the car ZERO noise

2. I reconnected the front speaker RCA system only which are DB Link Competition series, NO NOISE.

3. I reconnected the second set of RCAs bam, alternator whine was back, the second set being KnuConceptz RCAs that came with the amplifier installation kit I bought from them.

4. Disconnected the DB Link RCAs (front) and left the KnuConceptz (rear) plugged in, no alternator whine

So the problem only occurs when BOTH sets of RCAs are connected, and not individually, so I do not believe it to be a bad set of RCA cables..

Click to read more...

 

[BrownVanMan 10+ year member]

tried hooking up the knu rcs's alone? if theres no wine when those are in alone id be willing to bet its a HU issue

 

[AndrewH05]

tried hooking up the knu rcs's alone? if theres no wine when those are in alone id be willing to bet its a HU issue

Yes, that was what I attempted to say in Update 2 but it doesn't sound right, I get zero noise when either set of RCAs are connected by themselves, only when both are connected do I have an issue.

 

[BrownVanMan 10+ year member]

then i would bet its an RCA issue

 

[AndrewH05]

then i would bet its an RCA issue

Does it matter if I ground them at the amp rather than the back of HU? That way I can run them to the same ground as the amplifiers. Re running the RCAs is literally the last thing I'd ever do. I ran them on the opposite side as the power cables and seeing as there's no issues when either one is plugged in but not both, I can't imagine the issue is the RCA, if one was picking up interference it would do so regardless of whether or not both are connected.

 

[Only The Best 10+ year member]

might be a bad amp. plug another one in the same spot to rule out that option

 

[AndrewH05]

might be a bad amp. plug another one in the same spot to rule out that option

At least I don't believe it is amp, here's what I did today.. I removed the dash and pulled out the head unit.. I disconnected the RCAs from the HU, no whine. I reconnected one set, no whine, disconnected first set, connected second set, no whine. Then I ran a new ground, in multiple spots, one even being straight to the battery, with both RCAs connected still got frickin alternator whine!

Is it possible that with both RCAs connected the amp is trying to ground itself through the RCAs? There's only two options, maybe 3 left.

1. Bad HU

2. Bad RCAs (highly improbable as neither has any noise when connected alone)

3. The amp is sending it back through the RCAs this is how my power set up is..

2 amps connected via power and ground to Rockford Fosgate CPCC25 capacitor, and the main power goes into the capacitor and the main ground goes out of the capacitor. My ground from the capacitor is 4 gauge and is unfortunately longer than 18" is more like 30"..

I need to know what I should try.. My return Window for the amp and head unit close in 4 days...

 

[Only The Best 10+ year member]

what kindo f amplifier is it and who did you buy it from?... ij ust recently got a fosgate 600.5 amp and had the same problem you are having but I know it was the amp. if you have another 4 channel amp, try to plug it in and see what happens... otherwise contact the company you got it from that you are having problems with the amp and/or HU and are troubleshooting ATM to find a problem, most places are nice.