High-pitched whine in stereo speakers

[Photo_G]

Hi,

I hope someone here can help with some suggestions on how to track down and eliminate a high-pitched whine in our stereo speakers while the motor is running. It doesn't happen then the motor is off and, interestingly, it doesn't happen when we're running on the starboard battery, or when the port and starboard batteries are combined - only when running on the port battery alone. I picked up an RCA Ground Loop Isolator and connected it between the head unit and the amplifier, but that didn't affect it at all.

My near-term plan is to just run the batteries combined, but I'm curious whether someone thinks that this might cause a problem of some sort. Longer-term I really want to figure out what's not connected up right, assuming that it's actually a ground loop (which was my first and best guess).

If someone has any suggestions, I'd be very appreciative!

Thanks in advance,
G

[NautiGirl]

You are on the right track /w the Ground Loop. The issue is the head unit and the amp's are grounded to two different points in the boat. Where are the amps grounded? I would run a ground from that point to the head unit and see if that fixes it. It should.

Also, assuming they are close, you can try grounding the head unit to the amp ground terminal as a troubleshooting step. I wouldn't leave it like that, but it will help you figure out what you have going on.

Make sense?

[Photo_G]

Thanks!! There's only one amplifier, it's a Kicker DX100. I'll have to try to trace the amp ground wire the next time I'm at the slip (it's too cold today, for me anyway). In this instance, do you think that it's could be problematic to just run the batteries combined? I don't want to fry anything, you know...

G

[NautiGirl]

Thanks!! There's only one amplifier, it's a Kicker DX100. I'll have to try to trace the amp ground wire the next time I'm at the slip (it's too cold today, for me anyway). In this instance, do you think that it's could be problematic to just run the batteries combined? I don't want to fry anything, you know...

G

Your call - it won't hurt anything but if you sit in a cove and listen to the stereo /w the switch in combine there is nothing stopping you from killing both batteries. Just something to be aware of.

I would start by tracing the ground and see where that gets us. Our head unit is in the glove box and was grounded to the port battery. Dunno if that was factory or not. Don't worry about frying anything......if you mess up a ground nothing is going to fry, course it also won't power on

[Big Block Power]

Yep Agree with Mr Nauti. Find your factory amp grd. Could be going to the grd block on the transom wall. You will want to run a new head unit grd to there.

[Photo_G]

Awesome! Thanks so much for the great advice!!

Take care,
G

[NautiGirl]

Yep Agree with Mr Nauti. Find your factory amp grd. Could be going to the grd block on the transom wall. You will want to run a new head unit grd to there.

I would be careful using the ground block on the transom. I had originally planned on it, but when I took a closer look I found the wire that connects the ground block to the engine was 10ga. So all the work I did running nice 4ga ground wire would have been for nothing had I gone that route. If the ground block on your boat has a nice big wire to the engine block then by all means use it, ours just didn't. Remember, the ground has to be able to handle as much current as the positive battery cable.

My opinion you didn't ask for? Run 4GA from the amp to the negative battery post. Run 14ga from the head unit to that same battery. Done and Done.

My opinion only, we still haven't heard our stereo with the engine running so I could be posting in a month or two with a totally different plan.

[Photo_G]

Wow, that's some great insight, thanks again!

G

[NautiGirl]

Wow, that's some great insight, thanks again!

G

Take my experience /w a grain of salt. From what I have seen Cobalt didn't have a real strong handle on in boat entertainment back in 2007. I have crawled around a couple of the new boats - and gotten some really weird looks while doing it, turns out most people dont care about speaking wiring - they are doing a really good job of stuff now.

Maybe the Malibu influence, maybe they hired a 18 year old kid who lived in Neodesha and had a really nice system in his car as a consultant, who knows. Either way I would check out where the amps and the head unit ground before you do anything radical to your boat.

[Photo_G]

You have way more experience than I do, so I really appreciate your help! If I can't get a good handle on it though, I'll probably have the marina tech's take a look. Or, I'll just run them combined while underway and switch to port only after shutting the motor down. At least in the near term, that strategy will keep my Wife from cringing (it's pretty shrill).

Thanks again,
G

[okielaker]

found this:
Alternator noise can be heard in radio and stereo equipment as a high-pitched whine that increases
as the engine speed increases. A 0.5-microfarad, 50- to 100-volt, 40-amp coaxial capacitor
(www.jameco.com) or an alternator filter can be installed on the alternator to suppress the
interference.

https://www.boatingmag.com/ask-ken-elim ... nce#page-8

Don't know why that would manifest on only one battery source, though.

[Photo_G]

Thanks, that's a great article...very helpful!

G