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Andrzejsl

Question for Stereo Experts

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Andrzejsl

So I've got a constant low whine on my stereo but only when the engine is running after switching my amps out to a single 5 channel class D amp, crystal clear when engine is not running. I know this sounds like a ground loop problem but hear me out here. I've got a 2007 malibu response lxi silver edition with the hammerhead engine, and I've got 4 JL Audio MX650-CCX-SG-TB 6.5 for the cabin, 2 Infinity 6000M on the tower, and a sub under the observer seat. The amps have been installed in the same spot every time I've swapped them, under the observers seat on the wall.

 

Before Setup (no problems or whine, I only changed because the whole system was underpowered):

Rockford Fosgate Punch P450.4 4-channel car amplifier amp 60 watts RMS x 4 (to run the speakers)

Kenwood KAC-7203 1000w 2-Channel Car Amp (to run the subwoofer)

 

After Setup:

JL MHD900

 

So the only thing I changed were the amps. I even bought a new JL MHD900 to test it out but still the same problem, so I figured the problem was not the amp. So I then put in RCA ground loop isolators on the lines to see if I could cut out the noise, no luck. I also rewired the radio to come directly from the battery, no luck. I even bought a new radio, new RCA cables and using alligator clips ran the stereo outside of the boat and powered it directly from the battery, no luck. So I figured maybe the fancy HD MDH900 amp was too sensitive, I bought a Exile Audio Javelin 5 channel amp since this is what a lot of people use in boats so thought it would be happier, no luck.

 

Current Setup

Exile Audio Javelin 5 Channel

 

So any input or ideas here would be helpful, or should I just give up on modern amps and revert back to the underpowered old school setup. Thanks in Advance.

560f5hn.jpg

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kx250frider617

I had the same problem when upgrading to high powered amps. What fixed mine was running all the power and ground cables, all straight to the battery, Anything that is powered and part of the stereo such as head unit, Bluetooth modules, sat radio, etc. I then upgraded the power wires going from the batteries to the perko switch, along with sizing up the ground cables between all my batteries. 

I also ran better RCA cables, but those didn't make a difference. The cause of the noise is the voltage difference between all of your stereo components. The factory distribution blocks have a bunch of resistance after all the other electrical equipment is added. 

 

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MLA
1 hour ago, Andrzejsl said:

I know this sounds like a ground loop problem but hear me out here.

and it still sounds like a ground loop. So the only amp in the boat now is the 5 chnl and its driving the in-boats and tower speakers, plus woofer? The noise is present in all the full range speakers? Need to start by isolating where in the signal path, the noise is entering. 

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jonyb

How are the gains set?  How did you tune it?

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Andrzejsl

@MLA, and @jonyb, first of all thanks for the responses, much appreciated.

@MLA I only have 1 amp, rear runs the 2 cabin rear speakers, front runs the 2 cabin dash speakers and tower speakers, then the sub channel. Noise is present a full range. Here's a picture of one of the many isolation tests I've run. I've bought a new radio, new rca cables and completely disconnected existing radio from amp. I think plugged in RCA's from new radio to amp, powered new radio via alligator clips off of the battery (in picture below was off the dash side, I tried both sides to see if there was a difference). I also unplugged speakers, tried just fronts, rears, but still get it (noise is present on all speakers). Here's a picture of the setup I was using to test it. Is there another way I should try to do this?

csIN556.jpg

@jonyb, I've adjusted the gains, the more the gain, the more the sound, less the gain less the sound but it never goes away.

I've also have given up on doing this myself and had it done at a professional audio shop, I spent a lot of money and been there a few times but they havent been able to figure anything out either. The only thing left to try from my tech was moving the amp setup to another location in the boat, but I figured I'd reach out here before I do anything more to see what I can learn.

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TallRedRider

The ground and power lines from the head unit and amps should all terminate at the exact same location.  You might run a larger ground wire back to the engine block. 

I think it is more rare, but I think you can get noise from the turn on wire, which is probably connected to the keyed ignition.  So part of your system could sneak in power from an outside source if that were the case.  I moved mine to a switch on the dash, and the switch gets its power from the same place the rest of the stereo gets power.   Then EVERYTHING gets power from one source.  

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minnmarker
8 hours ago, Andrzejsl said:

@MLA, and @jonyb, first of all thanks for the responses, much appreciated.

@MLA I only have 1 amp, rear runs the 2 cabin rear speakers, front runs the 2 cabin dash speakers and tower speakers, then the sub channel. Noise is present a full range. Here's a picture of one of the many isolation tests I've run. I've bought a new radio, new rca cables and completely disconnected existing radio from amp. I think plugged in RCA's from new radio to amp, powered new radio via alligator clips off of the battery (in picture below was off the dash side, I tried both sides to see if there was a difference). I also unplugged speakers, tried just fronts, rears, but still get it (noise is present on all speakers). Here's a picture of the setup I was using to test it. Is there another way I should try to do this?

csIN556.jpg

@jonyb, I've adjusted the gains, the more the gain, the more the sound, less the gain less the sound but it never goes away.

I've also have given up on doing this myself and had it done at a professional audio shop, I spent a lot of money and been there a few times but they havent been able to figure anything out either. The only thing left to try from my tech was moving the amp setup to another location in the boat, but I figured I'd reach out here before I do anything more to see what I can learn.

I see the red turn-on and black ground wires going under the helm.  Where is the yellow wire getting power?

Try running red, yellow, and black all directly to the battery powering the amp.  Take all the boat's internal wiring, and any cross interference anywhere between observer compartment and helm, out of the equation and see what happens.

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Arick

I had a problem with noise/feedback.  I ran a ground wire straight from the deck to the battery.  Fixed my issue.

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Andrzejsl

@arick thanks for the suggesting, I already tried that with no luck. Any other ideas?

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Andrzejsl

@minnmarker, tried that too, that picture shows me running to the dash as the first test to see if my existing deck was bad, then I repeated this except when directly to the batter terminals. No luck. Any other suggestions?

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Andrzejsl

@kx250frider617 what size cables were you using?

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IdahoAxis

Where is your battery grounded? Have you checked that it's secure? Have you checked all connections to a battery selector/ACR/on-board charger? How about new battery cables?

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Andrzejsl

@IdahoAxis, Grounds are secure and solid goes to the motor, I recently replaced the alternator so know they are all good. I'm going to probably give the new battery cables and up the size a try. Thanks.

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