Stereo Alternator Whine

LMBoat

LMBoat

Well-Known Member
Oct 4, 2006
757
Ft Lauderdale
Boat Info
1999 450 EB
Engines
Cummins 6CTA's
Hi all,

I have a Clarion amp on the bridge that has an alternator whine. I've tried the Newmar filter, changing power and ground leads without success. Any other recommendation?

Thanks
 
LM,

Does your boat have a dual battery setup? If so, I would look into where the head-unit and amp are drawing their B+ from first. With a dual battery setup, it is crucial that all audio components share the same battery termination. If not, this invites noise, such as what you have.
 
Wylie_Tunes said:
LM,

Does your boat have a dual battery setup? If so, I would look into where the head-unit and amp are drawing their B+ from first. With a dual battery setup, it is crucial that all audio components share the same battery termination. If not, this invites noise, such as what you have.
Click to expand...
Help me please as well . . . is it not as equal importance for ground (B-) as well?
 
HIFI said:
Help me please as well . . . is it not as equal importance for ground (B-) as well?
Click to expand...

Excellent question and the answer is yes, but let me explain why I did not focus on the location of the ground in this example.

Since the stereo system is currently functioning, we know the head-unit is grounded. In almost every marine dual battery setup, except for a few custom applications, both the house and main battery banks are connected to the boat's common ground plane in some way. The banks may have a ground cable connecting each bank's GND post to each other, then the main battery GND running to the engine block, or both banks home run to the engine. Either way, both banks share the same ground plane, and therefore so does any audio componant that is wired up and working. Does that make sence?

So, this leaves us with the head-unit and amp's B+ terminations. With a dual battery system, the head unit can realistically be wired to the main battery and the amp to the house battery. At this point, noise can be entered into the audio path via the one thing that connects those two pieces of audio gear, the RCA's. When there is even a slight difference in potential (voltage level) between both bank, they try to equalize through the RCA and we hear noise. 99% of the boats that come to me or I get call on, as well as answer through boat forums, with a noise complaint like this, is traced back to the added gear like an amp, not sharing the same battery source as the head-unit. Even a remote MP3 dock that charges the unit can be a source for noise if its B+ is not on the same circuit as the rest.

Hope this help clear it up.
 
Last edited:
Wylie_Tunes said:
Excellent question and the answer is yes, but let me explain why I did not focus on the location of the ground in this example.

Since the stereo system is currently functioning, we know the head-unit is grounded. In almost every marine dual battery setup, except for a few custom applications, both the house and main battery banks are connected to the boat's common ground plane in some way. The banks may have a ground cable connecting each bank's GND post to each other, then the main battery GND running to the engine block, or both banks home run to the engine. Either way, both banks share the same ground plane, and therefore so does any audio componant that is wired up and working. Does that make sence?


Hope this help clear it up.
Click to expand...

Very well explained . . . And Thank You!
 
As a follow up question and more help to me, the OP and everyone else . . .

Does the AC side of the boat share same ground as the DC side of the boat?

I think there are issues where people try to integrate some of the cabin AC electronics (TV,DVD) with the cockpit DC hifi system and the same RCA grounds cause issues. And we know up front these mixing of components share different B+ power connections.
 
Are we talking an AC device thats receiving AC through an on-board inverter connected to the boats batteries, or are we talking all DC devices that are fed via AC shore charging thats running through a converter with its outputs going to the batteries?
 
Wylie_Tunes said:
Are we talking an AC device thats receiving AC through an on-board inverter connected to the boats batteries, or are we talking all DC devices that are fed via AC shore charging thats running through a converter with its outputs going to the batteries?
Click to expand...
Well . . . my first question still stands . . is the AC system ground shared with the DC system ground.

To answer your question . . . Example . . . someone tries to connect the audio out from the AC TV because they want to watch the game/movie and play it through the 12 volt stereo system.

Thanks for staying with me on this.
 
Wylie_Tunes said:
Excellent question and the answer is yes, but let me explain why I did not focus on the location of the ground in this example.

Since the stereo system is currently functioning, we know the head-unit is grounded. In almost every marine dual battery setup, except for a few custom applications, both the house and main battery banks are connected to the boat's common ground plane in some way. The banks may have a ground cable connecting each bank's GND post to each other, then the main battery GND running to the engine block, or both banks home run to the engine. Either way, both banks share the same ground plane, and therefore so does any audio componant that is wired up and working. Does that make sence?

So, this leaves us with the head-unit and amp's B+ terminations. With a dual battery system, the head unit can realistically be wired to the main battery and the amp to the house battery. At this point, noise can be entered into the audio path via the one thing that connects those two pieces of audio gear, the RCA's. When there is even a slight difference in potential (voltage level) between both bank, they try to equalize through the RCA and we hear noise. 99% of the boats that come to me or I get call on, as well as answer through boat forums, with a noise complaint like this, is traced back to the added gear like an amp, not sharing the same battery source as the head-unit. Even a remote MP3 dock that charges the unit can be a source for noise if its B+ is not on the same circuit as the rest.

Hope this help clear it up.
Click to expand...

Man, I wish you were in my area! I would love to have someone that knows what he's doing install my new system. The buddy I had lined up took a job installing home theater systems primarily in Manhattan and that doesn't leave him any time for sidework. The other references I have got never return calls so I just throw them on the pile with all the other discarded losers I have encountered in the past.
Thanks for that explanation, especially in terms that I can understand.
 
Thanks for compliment TD, I hope the info helps. If you where any way close, I would be happy to help directly. Good luck, I hope you finally find someone local.
 
I have a feeling he'll find someone soon.....

Dale
 
MasterFab said:
I have a feeling he'll find someone soon.....

Dale
Click to expand...

Dale,
Do you know something that I don't? Lol
I am resolved to having to install myself but not sure I will have the time. I still have to finish installing the rest of my VHF radios & other electronics that I R&R'd last season when I had the arch & windshield off. That's when I got the fiberglass in my eye & resulting infection.


Sent from my iPhone using Tapatalk
 
Wylie_Tunes said:
Yes, and if the AC TV thats plugged into the boat's AC receptacle has a 3-prong plug, then it also shares the same ground plane.
Click to expand...
WT . . . With that said . . . is there or is there not noise issues for folks that mix cabin AC components with cockpit DC components? The reason I ask is I was told this is not a recommendation a professional installer makes.

I am not trying to pollute this thread . . . this may be relevant.
 
Guys,

Thanks for the discussion. Yes, a 2 batt setup. At the bridge, I have 2 seperate 12 v circuits, one for helm power and one for the electonics, but I don't know if either of these is on the same batt as the head unit which is down in the salon. I will be at the boat tomorrow and will check.

BUT, my problem is only when the engines are running. If they are not, all is good. Does that help trouble shoot at all?

Thanks again!
 
Larry,

When the audio gear shares different power sources, its when the alternator is charging, that we tend to get that noise, so I think you are on the right path. One thing you can do as well, is to pull the RCA cable from the amp, power up the system and then fire up the engines. If the noise is gone, we know its coming in on the source signal cables.
 
Hifi,

With electrical, there is always "noise" present, so we do all we can to prevent it from entering the audio gear. Once in, the amps will do their job and amplify it and the speakers are more then happy to reproduce it for us to hear :smt021 In regards to having an AC TV and wanting to take the audio out to the DC head-unit, I suppose the chance for unwanted noise goes up. One way that I have had luck with in integrating these two systems, is to use the TV's 3.5mm head-phone port out to the head-units AUX input. One could even do this bluetooth and have no hard wire link at all.
 
might just be a bad diode in one of the alternators, can only be detected using a scope.It`s called "ripple"
 
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