RCA Run by Battery

[charha01]

I've installed a Pioneer AVH-2500NEX head unit in my car and paired it with a Kenwood X802-5 eXcelon amp. I cannot get rid of what sounds engine noise coming from the alternator and was hoping for some advice. I've changed the grounding point for the amp to several different spots, even grounding directly to the battery ground and that has made no difference. I've also run a 4g ground wire from the battery to the head unit ground to see if that would help but it also made no difference. The RCAs coming off the head unit go through the firewall and are routed behind the battery since that was the only path that would work for the installation. Could this be causing the issue?

Is there anything I can do to find the cause of this noise?

If it is the RCA cables, is there anything that can be done to shield them from the battery? They are shielded cables, but I'm wondering if their proximity to the battery is causing the issue.

Also, I'm using the factory power wiring to power the head unit. Should I run a dedicated wire from the battery for this instead?

Should I ground the chassis of the head unit in addition to using the ground wire coming off it?

I've read that you can install filters for alternator noise, but all the ones I've seen online look too cheap or get bad reviews, so is there something that someone would recommend?

Any help would be appreciated. Thanks

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[marc2112 10+ year member]

You could try aluminized loom to shield your rca but I don't think that would really help. The big 3 upgrade is your best shot imo especially if you have an older vehicle.

Convoshield Aluminized Chrome Wire Loom Tubing

Convoshield aluminum chrome finish wire loom is a high temperature tubing designed to protect wires or cables from excess heat & any potential harmful fluids.

www.cabletiesandmore.com

 

[charha01]

You could try aluminized loom to shield your rca but I don't think that would really help. The big 3 upgrade is your best shot imo especially if you have an older vehicle.

Convoshield Aluminized Chrome Wire Loom Tubing

Convoshield aluminum chrome finish wire loom is a high temperature tubing designed to protect wires or cables from excess heat & any potential harmful fluids.

www.cabletiesandmore.com

Thanks for the response. What is "the big 3 upgrade"?

 

[marc2112 10+ year member]

It's basically beefing up your stock power/ground cables. Lots of vids on youtube showing how.

 

[n2audio 5,000+ posts]

Here's what I would try:
Make some shorting plugs -- take a pair of junk rca cables and cut them so there's just a few inches of cable. Strip the wires and twist the +/- together.
Disconnect the signal cables at the amp and plug in your shorting plugs. If the noise is still there its being generated at the amp. If it's gone it's coming from upstream.
If the noise is gone plug your rca's back into the amp and disconnect them at the source. Short the pin and the outer cylinder. If the noise is still there it's being coupled into the rca's. If it's gone it's coming from the source.
This isn't going to solve the problem, but should at least tell you where to focus your efforts. And maybe if you have a defective amp.

I had a bunch of alt noise in my last install as well - stock HU. I never eliminated it, but I made a huge improvement by doing away with my LOC and running my speaker leads directly to the rca inputs via some plugs I made. Amp gain was adjustable up to 8v. I ran at min gain, which was actually a bit higher than ideal, but worked pretty well.

Thanks for the response. What is "the big 3 upgrade"?

The 3 primary wires in your car's charging system: Alt output to battery, battery to chassis ground, chassis (typically firewall) to block ground.

 

[charha01]

Here's what I would try:
Make some shorting plugs -- take a pair of junk rca cables and cut them so there's just a few inches of cable. Strip the wires and twist the +/- together.
Disconnect the signal cables at the amp and plug in your shorting plugs. If the noise is still there its being generated at the amp. If it's gone it's coming from upstream.
If the noise is gone plug your rca's back into the amp and disconnect them at the source. Short the pin and the outer cylinder. If the noise is still there it's being coupled into the rca's. If it's gone it's coming from the source.
This isn't going to solve the problem, but should at least tell you where to focus your efforts. And maybe if you have a defective amp.

I had a bunch of alt noise in my last install as well - stock HU. I never eliminated it, but I made a huge improvement by doing away with my LOC and running my speaker leads directly to the rca inputs via some plugs I made. Amp gain was adjustable up to 8v. I ran at min gain, which was actually a bit higher than ideal, but worked pretty well.



The 3 primary wires in your car's charging system: Alt output to battery, battery to chassis ground, chassis (typically firewall) to block ground.

Thanks for the info. I'll give that shorting plug option a try. At least I'll know where to focus my efforts!

 

[1aespinoza 10+ year member]

Thanks for the info. I'll give that shorting plug option a try. At least I'll know where to focus my efforts!

I had the same problem with an old Pioneer Z2. Grounding chassis helped alot, but still had noise. Changed to an old amp for subs. No filters, x-overs, fades, nothing. Just pure gain. Well, the whine came back with a vengeance! I gave in and used the front rcas for both amps. Now it is clean as a whistle. Good luck.

 

[charha01]

I used the shorting plugs at the amp. I unplugged the RCA’s from the head unit and plugged in the shorting plugs on the amp inputs. The noise was gone. I then tried plugging in one set of RCA’s from the head unit and still noice engine noise on the speakers. I then plugged another set of RCA’s and the noise came back but much less of it. When I tried plugging all three sets of RCA’s the noise was back full again. Does this give anyone any info on what the cause could be. Does it sound like this is coming from the RCA’s?

 

[n2audio 5,000+ posts]

can you access the back of the head unit? I would plug them into the amp and unplug them from the HU. Short the center pin to the outer barrell.

That will tell you if it's being generated at the HU or coupled into the signal cables. I would be surprised if it's the cables. Assuming that's the case you might try relocating the HU ground wire -- especially if it's running through the factory harness.

There used to be an amazingly detailed noise troubleshooting guide. I'm pretty sure David Navone wrote it, but I can't find it anywhere.

 

[wew lad 5,000+ posts]

A battery will not induce RF noise into RCA's. At least it makes zero logical sense for it to. It's a passive device that actually reduces noise.

 

[charha01]

can you access the back of the head unit? I would plug them into the amp and unplug them from the HU. Short the center pin to the outer barrell.

That will tell you if it's being generated at the HU or coupled into the signal cables. I would be surprised if it's the cables. Assuming that's the case you might try relocating the HU ground wire -- especially if it's running through the factory harness.

There used to be an amazingly detailed noise troubleshooting guide. I'm pretty sure David Navone wrote it, but I can't find it anywhere.

Thanks for sticking with me on this. How would I short the center pin to the outer barrel? Would I take a cheap female RCA cable and cut the wire, then connect the two cut wires?

I'm running the ground from the HU directly to the negative battery terminal. It was going through the factory harness, but I read that I should connect it to the battery so I did that. I didn't see any difference in noise by doing that. I'm using a 4g cable (same as the power cable to the amp) to go from the negative battery post to the back of the HU, then connecting the HU to that.

 

[n2audio 5,000+ posts]

Thanks for sticking with me on this. How would I short the center pin to the outer barrel? Would I take a cheap female RCA cable and cut the wire, then connect the two cut wires?

That would work, but any little piece of metal wedged between the tip and barrel would work too. A paperclip? Small screwdriver. Small screw/bolt?

 

[huberoy123 10+ year member]

I had a similar problem with the stereo I installed in my daughter's car. I tried the inline noise suppression to no avail. The alternator stopped working and I replaced it. The whining noise disappeared. Have your alternator checked to rule that out.

 

[charha01]

I had a similar problem with the stereo I installed in my daughter's car. I tried the inline noise suppression to no avail. The alternator stopped working and I replaced it. The whining noise disappeared. Have your alternator checked to rule that out.

Does anyone know if they make a filter for alternator noise? I’ve tried the small RCA kind, but that didn’t work. I’ve heard that there’s some kind of filter that goes on the power line coming off the alternator, but I can’t seem to find one online.

 

[huberoy123 10+ year member]

Type "alternator noise filter for car stereo" in your search engine. They show the type that you install between the battery and alternator. You may want to look at some reviews to see if they work.