Ground Loop Isolator Location

[AlterEgo99 5,000+ posts]

If I have to resort to a ground loop isolator to remove some alternator whine from my iPod source, where are these little devices supposed to be installed? At the HU or at the amp?

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[nineball 10+ year member]

i don't think it matter much to be honest.

 

[AlterEgo99 5,000+ posts]

Yeah, guess not. Got a couple Stingers today that recommended hooking them up at the amp...did that temporarily and it did nothing to fix the slight alternator whine I have when on my iPod source. C'est la vie, they are going back!

 

[smoka 10+ year member]

Try grounding your rca's

http://www.caraudio.com/forum/showthread.php?t=198477

 

[AlterEgo99 5,000+ posts]

Wasn't sure this would be a good solution for an Alpine CDA-9887...if it won't hurt anything I suppose I can try it.

 

[350zspl 10+ year member]

are you using the ground from the radio wiring harness, to the factory ground in harness

try grounding the black wire in the aftermarket harness to bare metal behind radio if you have not already done that

 

[350zspl 10+ year member]

and are your rca and power wires running down opposite sides of the car

 

[Compjake 10+ year member]

Are you using RCA ground loop isolator or one that attaches to the power wire of your amp/hu?

If its RCA's connect at either end I believe..

If its Power wires then I would say connect it to whatever device is creating the whine.. I did this in my moms car by connecting a speaker to the speaker wires on the hu and listening for the whine.. since there was none I know the whine was being created by the amp or RCA's and not the HU, so I got a ground loop isolator for use on RCA's and connected one at each amp. Problem solved. Since then I moved the RCA's to the opposite end of the car and removed the ground loop isolators, you can only hear the whine now if the HU is on and the volume is all the way down.. but even then its minimal.

Good luck! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[AlterEgo99 5,000+ posts]

are you using the ground from the radio wiring harness, to the factory ground in harness
try grounding the black wire in the aftermarket harness to bare metal behind radio if you have not already done that

Yup, HU is grounded to chassis at same point as the amps...not using the OEM harness ground and am using 12 gauge ground wire for the HU. Amps are using 4 gauge. Maybe I should ground HU to another chassis point away from the amps? Again, I'd like to step by step determine where the noise is coming from first (if possible) before I start moving wires around.

 

[AlterEgo99 5,000+ posts]

and are your rca and power wires running down opposite sides of the car

Yes, power wires are coming in through the floor on the passenger side (there was an unused grommet for that, thanks GM!) and running under the passenger seat to the center console where the two stacked Alpine PDA's are located. trust me, it was the only place I could put them...believe it or not, NOT a lot of room in an '08 Chevy Silverado X-Cab...under the rear seat is a custom enclosure containing 2 10" subs, and there is NO other room available under those seats or behind them.

The RCA's are running directly from the HU, into the dash and straight down and back through the center of the truck to the center console where the amps are located. They never cross or even get close to the power wires. The only wires that have any power that get near these RCA's are the remote turn on wires, but I figured that these are so small and the RCA wires are top quality shielded wires that they shouldn't be having any effect.

 

[AlterEgo99 5,000+ posts]

Are you using RCA ground loop isolator or one that attaches to the power wire of your amp/hu?
If its RCA's connect at either end I believe..

If its Power wires then I would say connect it to whatever device is creating the whine.. I did this in my moms car by connecting a speaker to the speaker wires on the hu and listening for the whine.. since there was none I know the whine was being created by the amp or RCA's and not the HU, so I got a ground loop isolator for use on RCA's and connected one at each amp. Problem solved. Since then I moved the RCA's to the opposite end of the car and removed the ground loop isolators, you can only hear the whine now if the HU is on and the volume is all the way down.. but even then its minimal.

Good luck! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Thanks...I'm going to be using some of these forums and attempt to troubleshoot this step by step. It appears to be the iPod source via the high speed cable connected to the rear of the HU, but it may be something else.

When I connected the ground loop isolators last night, at the amp as suggested by the manufacturer, it made no difference. They had ground wires you could optionally ground so I did ground those as well at the same point where the HU is grounded and that actually made the noise much, much worse.

So, time to step back and test step by step, starting by disconnecting the RCA jacks at the amps and placing muting plugs on them and going from there. Should be fun! //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[SicAudio 5,000+ posts]

try using a dif temporary direct to battery power source for the HU and see if it goes away. I bet it will. the constant power on the new GM's is poopoo. Ill bet you will need to run a fused constant off the main underhood FB.

also try a dif ground spot first. if your amps chassis is grounded change it. that will create a ground loop as well. mounting the chassis where it can ground is a big nono. the only ground you want the amp to see is the big ground terminal never the chassis. and dont ground the deck to the same spot as the amp. multiple short grounds are better than lumping all of them in 1 spot.

 

[AlterEgo99 5,000+ posts]

try using a dif temporary direct to battery power source for the HU and see if it goes away. I bet it will. the constant power on the new GM's is poopoo. Ill bet you will need to run a fused constant off the main underhood FB.
also try a dif ground spot first. if your amps chassis is grounded change it. that will create a ground loop as well. mounting the chassis where it can ground is a big nono. the only ground you want the amp to see is the big ground terminal never the chassis. and dont ground the deck to the same spot as the amp. multiple short grounds are better than lumping all of them in 1 spot.

LOL! I have been discovering that most of the wiring in that **** GM OEM wiring harness is "poopoo". //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

Just so I understand, you are suggesting running a fused line directly to the battery, correct? Any issues with this new line being anywhere near the 4 guage amp lines (I have 2 of those bad boys running from the battery)?

Also, it seem like there should be some sort of noise filter one could install on the output wire of the alternator to eliminate any AC noise on the line. Do you (or anyone else) know of such a beast and if it would help? The stock alternator on my '08 Silverado is rated at 165 Amps so it would have to be able to handle that possible max. load.

 

[AlterEgo99 5,000+ posts]

try using a dif temporary direct to battery power source for the HU and see if it goes away. I bet it will. the constant power on the new GM's is poopoo. Ill bet you will need to run a fused constant off the main underhood FB.
also try a dif ground spot first. if your amps chassis is grounded change it. that will create a ground loop as well. mounting the chassis where it can ground is a big nono. the only ground you want the amp to see is the big ground terminal never the chassis. and dont ground the deck to the same spot as the amp. multiple short grounds are better than lumping all of them in 1 spot.

OK, I think I need to shorten up the grounds for the two amps. They are located in the center console but my ground point for them is up hear the gas pedal. It's only about 4 feet, but it is probably too long and both amps are grounded to that point. I think I can use some of the bolts at the rear of the front seats. That would only be about a 1 or 2 foot run for each amp. Separate ground points for each amp, correct?

Also, just to clarify, are you suggesting that I make sure that the amps are not screwed down in such a way that there is a ground via that attachment point? If so, yeah, I may need to check that as well, but I know that when I initially checked for this whine I had yet to actually mount the amps. After mounting the noise didn't seem to get any worse, but I will check it.

 

[nineball 10+ year member]

same ground spot for the amps. 1 less thing to worry about. if either makes noise, or both, try another ground point.