Stereo Noise Issue

[300sflyer]

Hey folks,

I have a noise issue on my stereo system that is driving me crazy. Last year I added an amp and 2 more speakers to our Monterey. It works great while I am hooked up to shore power, however when we are out on the water and our dual voltage fridge is running on 12V, I get this nasty static out of the extra two speakers. When the fridge turns off, the noise stops. The noise does not come out of the other 4 speakers connected directly to the head unit.

I have tried many things to try to resolve the issue. I have checked the grounds and the power wires, replaced the RCA cables with shielded ones, added a ground wire between the head unit and the amp, added a choke to the 12V line going to the fridge, and to the amp itself. I even replaced the amp itself with a brand new one, and I have still have the same issue.

When I disconnect the RCA cables from the amp, the noise is gone.

Thanks for your help!

 

[BrianNJ]

Check the voltage into the amp with the frig running and without. The frig is probably a pretty hefty current load and may be drawing down the supply voltage to the amp, which could cause clipping or other crazy behavior. A hefty amp can generate a pretty good load too. As an experiment, you might try running separate power from the battery to your amp and see if there is any difference. If there is a difference after the experiment, you will need to determine where the voltage drop is coming from by measuring voltage at as many places as you can access between batteries and the amp. If you are lucky, it is a poor connection somewhere. Or it could be you need a bigger gauge wire from power to the amp or frig or both. I have been to Georgian bay and hope to go back there someday.

 

[300sflyer]

I am pretty sure it is not a voltage issue. I have 3 group 27 house batteries, with about 6 feet of #6 cable going to the amp, directly from those batteries. I did try running the amp directly from one of my starting batteries instead of the house ones, and it made no difference.

Thanks.

 

[H20Rat]

So does it do it with no audio signal? Can you disconnect the RCA's and still get noise? The other thing I'd try if those are true is disconnect the blue remote wire and just jumper that from the positive going into the amp, with the RCA's disconnected. Basically do everything humanly possible to eliminate everything else that is electrically touching the amp.

 

[300sflyer]

When I disconnect the RCA cables, the noise is gone.

 

[midcarolina]

Sounds like you need a ground loop isolator.

 

[bruceb58]

It's your stereo that is picking up the noise.

Where does it get its power and ground? Where does the amp get its power and ground?

When you turn the volume of your stereo up, does the noise also increase in volume or is the static volume constant?

 

[300sflyer]

The head unit uses the original factory wiring from the main panel. The amp is wired directly to the house batteries. When the sound is turned right down to zero, you can still hear the static when the fridge is running on 12V. I cannot tell if the static is still there at high volume levels.

 

[midcarolina]

I was kinda tired when I posted my very short response last night.........so, first does the amp have an adjustable gain setting? are you running the built in amp in the head unit?
is the amp a mono amp pushing two subs?

 

[300sflyer]

I was kinda tired when I posted my very short response last night.........so, first does the amp have an adjustable gain setting? are you running the built in amp in the head unit?
is the amp a mono amp pushing two subs?

Yes, it does have an adjustable gain setting. It is set so the two additional 6x9 speakers, are at about the same volume level, as the other 4 speakers being driven by the head unit.

 

[bruceb58]

The head unit uses the original factory wiring from the main panel. The amp is wired directly to the house batteries. When the sound is turned right down to zero, you can still hear the static when the fridge is running on 12V. I cannot tell if the static is still there at high volume levels.

So does that mean the head unit is not on the house battery?

 

[300sflyer]

So does that mean the head unit is not on the house battery?

No, the head unit is also powered by the house batteries, along with the fridge, lights, water pump, etc.

 

[H20Rat]

added a ground wire between the head unit and the amp,

Did you disconnect the old one when you tested the new one? Given the latest posts, I would HIGHLY suspect the current ground and positive wiring of the head unit.

 

[300sflyer]

Did you disconnect the old one when you tested the new one? Given the latest posts, I would HIGHLY suspect the current ground and positive wiring of the head unit.

Not sure what you by remove the old one... The main +12V and ground for the amp is #6 wire. At the suggestion of a local stereo installer, the ground was added between the case of the amp and the head unit. The head unit works perfectly with its current wiring, except when the 2nd amp was added, and only then do I have an issue when the fridge is running.

 

[bruceb58]

I would do a test where both the amp and head unit are running of the exact same battery using the exact same ground. That may mean running new power/ground from the head unit to where the power gets attached. That may be the only way you can solve this issue anyway.

 

[midcarolina]

Try and turn the amp in the head unit off and see if noise goes away.........btw what amp do you have?
Sometimes the trigger wire from the head unit can cause noise, you can unhook the trigger and jump from amp power and see if noise goes away.

although I still think a ground loop isolator will fix the noise, It really is just a cover up of the issue! all be it a easy cover up

 

[300sflyer]

Try and turn the amp in the head unit off and see if noise goes away.........btw what amp do you have?
Sometimes the trigger wire from the head unit can cause noise, you can unhook the trigger and jump from amp power and see if noise goes away.

although I still think a ground loop isolator will fix the noise, It really is just a cover up of the issue! all be it a easy cover up

Can't turn off the amp in the head, without turning the entire stereo off... it is built in. All of my stuff is Pioneer. The replacement amp I bought which did not help is Clarion.

Do you have a recommendation for an isolator?

 

[midcarolina]

Hmmm...... I have a pioneer super tuner in my boat and can adjust power settings in audio to bass boost on/off and different power levels,

On the isolator I think one is just as good as the other........it's a simple device, Any big box store, radio shack or the like carry them.

 

[bruceb58]

Just so you know, you will lose some audio quality if you use the isolation transformer, especially cheap ones with low quality transformers in them. That may not matter to you since its in a boat.

Personally, an isolation transformer is a band aid fix.

You said in your first post you added a ground between the head and the amp. How did you connect them? Hopefully not to their cases but to the ground input themselves.

How is the fridge wired? May help to twist power and ground leads together to the fridge. I actually do twisted power leads on anything that I want to reduce noise on including depth sounders and radios. A very large capacitor at the power input to the fridge may also help.

Check out this link:

http://continuouswave.com/ubb/Forum6/HTML/001038.html

 

[midcarolina]

OK, I talked to a buddy of mine who is a stereo guru, He said Pioneer head units are notorious for blowing the smd fuse inside the head unit, said this typically happens if the rca cables are unplugged while head unit has power.

He said the work around fix to the problem is to use wire strippers to expose the shield on both ends of the rca cable, then use a piece of wire to ground both ends of the rca cable.