Ground loop? Alternator whine! Southern Cali help!?

[nictlg7]

I have an unbearable alternator whine! I have been diagnosing it for weeks, and I am about to give up and rip everything I just purchased out! I think I have a ground loop, because the whine gets louder when you rev the engine. It only happens with the car started, from what I can tell. What I have in the car is as follows:

Stock receiver with Sirius radio hooked up (under passenger seat)
Grounding kit in engine (if it may contribute to ground loop?)
4 gauge wire running from Stinger battery terminals along drivers side to trunk
into a Stinger HPM series fused ground/power distribution block
8 gauge wire running from distribution block to 1 4 channel MTX amp
(I wanted to be able to run to my stock Kenwood amp and/or MTX 2 channel amp if I ever run all of the speakers off the 4-channel and save the 2-channel for the subwoofer, or if I run the stock subwoofer along with my Infinity)
out of the 4-channel amp is 12 gauge twisted wiring running to two Kenwood eXcelon series crossovers that run to the components: 5 1/4 mid and tweeters - Please note amp, then distribution block, then crossovers are all mounted next to each other in that order in a custom carpeted box)
For signal wires, I have Rockford Fosgate twisted RCA cables, and I have tested with the stock cheap RCA wire as well)

Also, tonight I disconnected the stock wiring. I found the crazy harness they use on the drivers side behind the back seat in the trunk, and disconnected it. I also clipped the wire when I ran the power wires into the battery terminal, and I disconnected the stock amps ground, which was the bolt I used for my ground wire. Oh yeah, the ground wire is only about 2 feet long, running from that custom box, under the back seat supports, over to the drivers side rear seat bracket, where I mounted it with a huge Rockford Fosgate 4 gauge ring terminal. It has been mounted to bare metal, as well as the seat bracket with paint scraped away for a good contact, with no change to the noise. If you disconnect the RCA for the components, you don't hear any noise in the subwoofer, but perhaps it can't pick up that high a frequency? If you connect only the components, or the components with the subwoofer, the sound is the same. It changes slightly depending on which wire you use and which output (front/rear/non-fading) you choose, but it is not a very noticeable change. I don't know where else to go with this unless I should ground it off above the factory amp rack. Someone on here suggested that in a thread I read. Does the cross-overs being next to the distribution block and power/ground wires have anything to do with this? I have better 16/12 gauge twisted wire and another twisted RCA cable from Fosgate on the way to help cancel the noise, but I am not sure if that will resolve the issue. I am thinking...not! Where might my ground loop be coming from? Anyone in Southern Cali who can fix it, I have cash!! Hah...thanks in advance for any help anyone can provide, thank you!

 

[Greg S]

Two things I can think of to try.

1st:
Move the x-overs away from your power wires, don't think htat is the problem but it's not a good idea to have them there.

2nd:
Run a ground wire from the eadunit back to the amps to make sure you don't have a poor ground at the radio, common problem of ground loops.

3rd:
If these don't work PM me and you can bring it by my place and I'll have a look at it but it'll be a bit of a crive as I'm in Valencia.

 

[sndsgood]

youve allready found the culprit, you said when u disconnect the rca's then the noise stops (alternator whine) this means the amp is not the problem. so it is eather your headunit or the rca's. disconnect the rca's and then take a speaker and run speaker wire from your headunit to your speaker, is the noise there? if so the noise is entering your headunit, if its not its entering your rca', if its entering your rca you should try and find a new route for it. but i bet more then likely the noise is entering your headunit wich means first trying a new grounding location, i'd do as poseur suggested and grounding to the same spot as your amp. or find another better ground in the dash.



fixing noise problems is all about tracking where the noise enters the system, once that done 90% of the time youlle find that the problem can be fixed without spending a dime.

 

[Poseur]

Wow now I'm making ghost suggestions???

My big thing 'cause it happened to me is to wrap the metal ends of any exposed RCA's There's a BAD grounding loop in that vertical support behind your HU that those thigns'll inevitable touch.

 

[sndsgood]

lol just looked up and thought i saw your blue protege so i assumed it was you, sorry about that greg s

 

[1sty]

Update?
Is everything solved?

 

[nictlg7]

Wow, I have been so busy the last few days, I have forgotten about this thread. I appreciate everyone posting and trying to help me out. I am not very experienced when it comes to car audio. I can do the basics, but this ground loop is killing me. I actually had taken a break from it and have been fighting with my HKS BOV and Spool hardpipes for several days now. I want to spend time this weekend fixing the audio properly. If anyone wants to help out, I will buy the pizza and drinks (within reason, hah). (cheers)I don't
know many people around here. All of my car buddies who used to help me are too far away to know what they are looking at.

That is good info about grounding the head unit. My new Rockford Fosgate twisted RCA cable should be here soon, they should help. I have one already, but I am running 2 sets currently, and the other RCA is not twisted, and may be causing some distortion? At any rate, I would appreciate some help if someone has a few hours. Thanks so much guys, you rock! (rockon)

 

[nictlg7]

How should I ground the head unit, btw?

 

[Shane5425]

the altenator whine, is it loader with the ac on, some reason i have a whine like that, but only with the ac on... if i turn the ac off u dont hear it....

 

[sndsgood]

first off i'd just hook a length of wire to the headunit ground then try sevearl diffrent locations, if you find one of them gets rid of the noise, go ahead and route it cleanly out of the way and hidden.

 

[nictlg7]

Hmm, that is interesting. I will try to work with the head unit. I never had any issues before the component speakers came along. Is this because the subwoofer would not handle the frequency where I hear the whine? Also, it does get louder if the defrost, lights, and other accessories are on. That makes sense, correct? I will keep working with it. Thanks again!

 

[1sty]

I assume the component speakers came along at the same time as the amp for the front speakers though?

A sub won't be very audible if its amp is in a ground loop becuase of the crossover just like you said, but sometimes you can tell. If your using the factory ground on the head unit then so long as its a good connection I doubt its your problem. My money is on the amps or the RCA cables.

What happens whne you disconnect the RCA cables form the amps, does the noise go away? If not, then we know its a ground loop on the ground cable. If it does go away then we know the RCAs are either picking up noise or are a ground loop of there own.

 

[nictlg7]

I assume the component speakers came along at the same time as the amp for the front speakers though?

A sub won't be very audible if its amp is in a ground loop becuase of the crossover just like you said, but sometimes you can tell. If your using the factory ground on the head unit then so long as its a good connection I doubt its your problem. My money is on the amps or the RCA cables.

What happens whne you disconnect the RCA cables form the amps, does the noise go away? If not, then we know its a ground loop on the ground cable. If it does go away then we know the RCAs are either picking up noise or are a ground loop of there own.

Actually, I haven't hooked the amp up to any of the stock speakers yet. I was going to, but I wanted to get a handle on this situation first. I would like to have all of the speakers, or at least all but the ones in the rear doors, run off of my MTX/Kenwood amps. That way I will get a much better sound from the system all around. I don't like just bass. I like my highs, and I like a nice, full sound!
The ground loop can only be heard when you swap the RCA cables from the sub input to the component speaker input. At that point, you can hear the alternator whine very easily. As you rev the engine, it increases. So it is definitely a ground loop, but how can you tell if it is the cable or the amp, or a certain ground? I have tried 4 different style RCA cables, and they have all had the same effect. I can minimize it by changing the settings for the gain or whatnot, but that isn't the fix I want. So what are we thinking, the grounds? the amp? (I think I have tried both the MTX amps) or the cables? Hold up, idea. I am going to get a picture of the setup, and post it here. One sec...

 

[Greg S]

I definitely would move the x-overs away from your power distribution, it's just too close for comfort. Also a great way to test if the noise is at the amp level or before is to use a set of shorting plugs. Basically a cheap RCA that has one end cut off and the positive and negative connected to each other and plugged back in to the amp input. If you still have whine then it is being introduced at the amp level or after, if not then it is at the headunit or RCA portion.

 

[nictlg7]

Hmm, I will try to check some of these things out this weekend, I guess. I still haven't received my new twisted RCA cables. I am about to give up and file on Ebay to get my payment back...

 

[sndsgood]

well youve allready determined its not the rca's themselves. the second set of rca's you tried answered that for you.

heres a hint 90% of noise is a bad ground issue. did u try changing the grounds of the headunit? did you try hooking a speaker up to the headunit, if you did this and the speaker played alternator noise, then u know the problem is entering the radio. if there is no noise u know the noise is not entering the radio but it is entering the amp itself. try that and let us know what u find out.



i would also try moving the crossovers away from the power wire, that is pretty close together. also looks like u scratched the paint for your ground. take that thing off, get some sandpaper and sand it nice and to the metal, get rid of all the paint. that piece looks like its painted on both sides so the opposite side of it may not be making a proper ground to the other metal piece

 

[nictlg7]

well youve allready determined its not the rca's themselves. the second set of rca's you tried answered that for you.

heres a hint 90% of noise is a bad ground issue. did u try changing the grounds of the headunit? did you try hooking a speaker up to the headunit, if you did this and the speaker played alternator noise, then u know the problem is entering the radio. if there is no noise u know the noise is not entering the radio but it is entering the amp itself. try that and let us know what u find out.



i would also try moving the crossovers away from the power wire, that is pretty close together. also looks like u scratched the paint for your ground. take that thing off, get some sandpaper and sand it nice and to the metal, get rid of all the paint. that piece looks like its painted on both sides so the opposite side of it may not be making a proper ground to the other metal piece

What I don't understand...is the ground I am using is the same one they used for the factory amp, which was a very thin wire, also. It was even on top of the paint. I am going to dremel or sand the paint off. or ground it to a location where there is no paint. I will also try your head unit suggestion this weekend. If anyone is going to be around the Long Beach/Orange County area...maybe they could take a look at it. I would be more than happy to drive someplace nearby if I could have someone take a look...Thanks for all the advice!

 

[nictlg7]

Another pic of the components...I am selling these if I can't install them properly this weekend. Hah!

 

[sndsgood]

the ground wire you were using was fine when you were just sending 8 watts to the facotry speakers, now you are taking that signal and having your amplifier amplify any sound traveling down the wire. noise that u couldn't hear at 8 watts can now be heard when amplified 20x.