That noise......

[Motovet 10+ year member]

Stumped, even after going through a few searches. Anyway what I thought was an HU issue is an install issue. Getting noise from front speakers...kinda like a short wave radio that's not tuned in. Anyway tried swapping around the RCA's and still noise on fronts. Hooked up a home CD deck to front amp...and sound gone. HU problem I figure...must be ground? So try grounding everywhere, even to the battery, and still have noise. Another thing that's wierd is with another HU the sound came from the front and rear speakers, now it's just the fronts. What is happening?

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[Motovet 10+ year member]

Anyone? I will add the noise is the same with the HU gounded....and not grounded.

 

[Frankensuby 10+ year member]

Hmm... I'd say

1.buy a set of RCA's from Wal-mart or something, and just run them through the cabin to wherever your amp is. Make sure not to get the RCA near the power wire

2. If noise is still present, swap out the amp for someone elses. Doesn't matter the power output, just as long as it can get loud enough to hear the noise.

3. If that does not work, try swapping out the Head Unit for another. At this point it leads to either ground loop isolation or the Head unit.

4. If the new HU swap does not eliminate this issue, buy a ground loop isolator from Wal-mart. Plug it in and see if this eliminates the noise.

Remember, use the new RCA for each setup atleast. Just to be safe.

Does the noise follow the RPM of the engine? I.E.- you rev it and it gains pitch with the RPMS?

If so, it could be the RCA Pre-Outs on your Head unit. I have had this issue on 2 decks now, both are Pioneers.

The first example was an Older Pioneer, which are known for their noise. I bought 2 sets of RCA Ground Loop isolators and it helped alot.

The newest issue was an injury I inflicted myself. I roasted the RCA Pr-outs because a ground came loose on an amp I was tuning, and it found a new ground through the RCA's. Pioneers fix for the old Pioneer noise issue was a form of fuse that protected and eliminated the noise in the RCA pre-outs. I blew that fuse up //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif The Unit is the new line DEH-6800, a great unit...when not messed up by said owner :lol:

Hope this may clear some things up for you.

 

[Motovet 10+ year member]

This noise is present with the accessory on, engine off. RPM's make no difference. I will try another set of RCA's, though I already swapped all three to that amp and it made no difference. The home player plugged into that amp and the sound is gone. This is also the second HU with the same noise. Thing that's wierd is with the HU gounded or not, it's the same.

 

[Frankensuby 10+ year member]

This noise is present with the accessory on, engine off. RPM's make no difference. I will try another set of RCA's, though I already swapped all three to that amp and it made no difference. The home player plugged into that amp and the sound is gone. This is also the second HU with the same noise. Thing that's wierd is with the HU gounded or not, it's the same.

What were the 2 decks make and model #?

What type of car are you running?

It honestly sounds like something to do with the RCA or deck source. If the amp is confirmed as not the issue, and you've grounded to everything short of straight from the battery, and your still having issues, I could only see it as deck or RCA problem.

Also, you've checked to make sure all of your speakers are on correctly? I've never had issues with this, but I've heard that reversed polarities can cause noise.

 

[Motovet 10+ year member]

2005 Tahoe. It's not the deck....If I ran the RCA to just the fronts, no noise. Fronts and rear, no noise. Add sub RCA to deck, noise. In fact I got the same noise with no RCA's to the deck. I disconnected the power to the sub amp, and no noise with all RCA's plugged in. My power to amps is like this: 4 guage from battery going to distro block. From distro, one 4 quage to front amp, and one 8 guage to rear amp. One 4 guage from battery to sub amp. The front amp is grounded in one location, and the sub and rear amp are grounded in another.

 

[Motovet 10+ year member]

This is driving me nuts. Anyone have a clue on this one?

 

[Frankensuby 10+ year member]

I'm assuming this only happens when the sub amp has power?

Grab 2 sets of Gound loop isolators. Wal-Mart sells them for 15$~ and they work. If you truly have some form of ground loop isolation, these will dramatically reduce the noise. If you open the Package carefully, you can return it too.

 

[helotaxi 5,000+ posts]

Ground all the amps to the same place. Double check the ground of the sub amp, it appears to be your problem. Make sure it has a sloid connection at the amp and make sure that the point you have it grounded is really a good ground, not all metal in the car has a good path to ground.

 

[Motovet 10+ year member]

I'm afraid it is the ground to the amp, and that sucks cause I'll have to undo alot of stuff to get to it. Strange thing is my small amp for the rears is grounded with the same bolt as the sub amp, and it is fine. The grounding spot for the Zed Duece, (fronts)is on the opposite side of the Tahoe, but the very same location. Also with everything hooked up the noise only comes from the sub and fronts, not the rears...sound about right?

 

[helotaxi 5,000+ posts]

It could just be that you have a bad connection for hte ground wire at the amp not at the ground point. I would check that first.

 

[Motovet 10+ year member]

That could be actually. I had to bend those wires pretty hard to fit it where I did. In fact I barely got all three amps to fit under the rear seat. I like your sig....I know so well running a large facility with many employees....not all smart.

 

[Motovet 10+ year member]

Well now I think it has to be the amp itself. I ran a new ground wire to the same place as the front stage amp that works fine, and no difference. Only way I can make the noise go away is by not powering that amp. Is there an easy way to bench test it to be sure before I return it? Or should I assume I am sure....what else can it be....

 

[Motovet 10+ year member]

Dammmmmit! It is not the amp. I tried another amp...and same **** noise. If I disconnect the power to sub amp all is quiet. I located the ground from the sub amp to the ground for the fronts, so that can't be a problem. This is what I have found prior to trying another amp, and re-grounding

1. Everything hooked up and home player off front amp = noise only comes through sub.

2.Everything hooked up, but RCA's off front amp = noise only through sub.

3. RCA's off all amps = less noise only through sub amp.

4. RCA's on front amp only = less noise through front speakers, and sub.

5. RCA's all off HU, but all connected to amps = noise through front speakers and sub.

6. Sub amp not powered = quiet.

7. Only sub amp powered = noise through sub.

8. Only sub powered and run off home player = noise through sub.

9. Different amp, and verified ground = all of the above.

Where could I possibly be picking up this noise? Also this is the second HU with same results.... AND this noise is constant...key in any position, and no change with engine running.

 

[Frankensuby 10+ year member]

I'd go insane if I was you haha. I really don't know what to say.

Have you ever done ANYTHING to your car that isn't stock besides the audio system?

I ask because someone plugged a monitoring system into the car and instantly he recieved noise into his system at any point the amplifiers were powered on. In the end it was a form of ground loop isolation.

Just another though to put out there.