Help w/ Premium Stereo Whining Noise

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lghtspeedz
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Help w/ Premium Stereo Whining Noise

Post by lghtspeedz »

Hi Everyone,
I'm a stereo newbie. Done a little reading and digging but hoping that some more experienced folks can help me out. I have a 2015 R7 w/ the Premium Stereo. It has the RF hidden system with 2 amps, 6 speakers in the cockpit, 2 on the transom, a subwoofer, and two tweeters near the dash. It's a decent stereo. Because it's old, the USB does not recognize my iPhone so I listen to music on bluetooth. When the system is on, I get a constant whine or drone. It doesn't seem to matter what mode I am listening to (it's the same with FM radio). I have been messing around with the two amps trying to tune it a bit. In doing so, I found that if I switch the zone that controls the bow speakers (and possibly another area) from High Pass/All Pass to Low Pass, the noise goes away almost completely. When I do that though, all I'm getting is bass, nothing midrange or above. Also, this high pitched whine/feedback drone gets worse when I hit the bilge blower and/or start the motor.

Based on what I have read I've narrowed to either a problem with the amp or a bad ground somewhere. The system itself is decent, a huge step up from our last boat. I'd prefer not to have to start replacing stereo components our first year with the boat.

Here are some pics of the components to help. Can anyone provide some suggestions for a complete novice on how to make this stop? I'm looking for grounds, I have no idea how to do that. The noise is subtle but constant and if I have it loud enough it kind of downs it out. But that's not always practical or possible. Thanks in advance!
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2015 Cobalt R7- Navy w/ Yellow Stripe and VP V8-380HP
2014 Stingray 225LR - Red with Mercruiser 5.0 260hp (FOR SALE!)
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jwill323
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Re: Help w/ Premium Stereo Whining Noise

Post by jwill323 »

When the engine is running does the whine change pitch with the RPM's of the engine? This is most likely a ground loop and due to a bad ground somewhere. check all the connections on the amps and head unit are tight and clean, can you follow your ground wires (the yellow ones) from each component back to where they are grounded? There will probably be a ground bus bar somewhere where they go to. check all of those screws and the ring terminal connections to make sure they are tight and there is no corrosion and the connections are solid and give the bus bar a spray with deoxit, also make sure your battery ground lugs are tight and clean. If all the components (amps and head unit) are not grounded to the same point (same bus bar) this is also a likely culprit. if all of the above checks out then look at your RCA cables, the ones you have in your picture are not very high quality and could probably stand to be replaced. These run from you head unit to the amps (the red and white cables). you may want to look into replacing those with something better i used theT-Spec v10 Series cables from crutchfield in my new install and was very happy with them. They were very inexpensive but do provide excellent shielding from external noise.

Also changing the high pass, low pass, full range setting to low pass is just blocking all your higher frequency sound, since the ground loop makes a higher pitched sound you are just not hearing it anymore, this could also damage your tweeters since you are now sending low frequency information to a speaker that is not designed to play low frequency so this is not good! put those settings back to how they were originally set and we'll get your root problem solved!
2007 Cobalt 323
Twin 496 Mag HO Bravo 3X
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2001 Sea Ray 280 BR (previous)
1988 Four Winns 210 Horizon (previous)
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jhnmdahl
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Re: Help w/ Premium Stereo Whining Noise

Post by jhnmdahl »

Great advice above. RCA cables are a common problem, and cheap to replace.

Another thing you could do is connect the RCA cables from the hidden head unit to a portable speaker, a boom box, or something else with an RCA input and speakers so you can hear if the whine persists. The real goal is to remove components from the system (e.g. the speakers and amplifier in this case) to isolate where the whine is coming from. Once you know that, you know where to focus your efforts.

John
Administrator of the www.cobaltchat.com Cobalt boats community forum
2015 210 (Volvo Penta 5.7L V8-225)
lghtspeedz
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Re: Help w/ Premium Stereo Whining Noise

Post by lghtspeedz »

This is all really good advice. Thank you both! I’ll try to play around the next time I’m out. I’ll probably end up reporting back with more questions. Thank you both!
2015 Cobalt R7- Navy w/ Yellow Stripe and VP V8-380HP
2014 Stingray 225LR - Red with Mercruiser 5.0 260hp (FOR SALE!)
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