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Dsingram

Engine whine on tower speakers...

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Dsingram

I recently had new, glorious wet sounds installed on the tower.  All was great in the shop but I get engine whine in the tower speakers.

I have a head unit connected to a WS420, this then runs to three amps.  One for the in boat, one for the tower, and one for the subs.

First thing I tried was a 12 gauge ground wire from the biggest amp (wet sounds) to the Ws420 and the head unit ground in parallel.

Then I cut the bundles and separated the power wires from the audio wires.

Now I can stop the whine by disconnecting the leads from the 420 to the towers at the 420.  This makes me think it is still at the head end or 420, but shouldn't a 12gauge ground be enough?

Any other ideas out there?

Thanks

David

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ThinkinBu

Think if you do some searching you will find its the 420.  Put one on my last boat and had hiss on the rev 8's.  Moved the 420 to the new boat with completely different audio gear and have hiss on my new rev 8's.  MC to BU.

 

Disconnect it from the system and see if it goes away.

 

 

Edited by ThinkinBu

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MLA

its likely not a ground problem, but rather a B+ problem. 

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David

A 12-gauge ground is more than enough for the EQ.

In the same manner in which you created a single ground point for all audio components in the signal path, you must do the same for the B+ side.

Alternator whine is not an issue with equipment but an issue with the installation. The identical wiring approach may be noise free in one boat but have noise in another boat. In your case both the B+ and ground must be isolated from the factory harness for all audio components.  

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Dsingram

Thanks!... Dumb question... What's a B+?  

Time to google.

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Dsingram

Got it.  B+ is positive battery leads... So the theory is the boat harness power comes off a different battery.  This is causing a voltage difference between the amps and the 420 / head unit power sources.  Could be both my quiet hiss and alternator whine.

Right?  So the solution would be to run a new power lead from the "house" battery feed directly to the 420 and head unit?

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minnmarker
13 minutes ago, Dsingram said:

Thanks!... Dumb question... What's a B+?  

Time to google.

 

Just now, Dsingram said:

Got it.  B+ is positive battery leads... So the theory is the boat harness power comes off a different battery.  This is causing a voltage difference between the amps and the 420 / head unit power sources.  Could be both my quiet hiss and alternator whine.

Right?  So the solution would be to run a new power lead from the "house" battery feed directly to the 420 and head unit?

Yep, Positive and ground from the stereo battery direct to the HU and EQ - both always-on and switched leads which means you'll have to use a separate switch if the stereo is currently on the key.

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MLA
38 minutes ago, Dsingram said:

So the solution would be to run a new power lead from the "house" battery feed directly to the 420 and head unit?

Maybe not direct to the battery, but to the same battery reference as the amps. if the amps are battery direct, then ok, if the amps are wired through the main battery switch, then ok. 

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David
1 hour ago, Dsingram said:

Got it.  B+ is positive battery leads... So the theory is the boat harness power comes off a different battery.  This is causing a voltage difference between the amps and the 420 / head unit power sources.  Could be both my quiet hiss and alternator whine.

Right?  So the solution would be to run a new power lead from the "house" battery feed directly to the 420 and head unit?

Yes, pretty much the theory. This is called a ground loop but can also apply to a supply loop. Different batteries of different voltage potential feeding different audio components in the signal path will force voltage to flow in places that it should not and thus creates noise. If everything is wired to the output post of a dual battery switch, the B+ battery conflict is not possible. However, it's not quite that simple, the same noise scenario can occur via different cable lengths, different cable sizes, and multiple connections, collectively causing the same voltage differential between audio components. You really don't know what's in a factory harness but with certainty it is a very roundabout path to the same supply source. Any path "resistance" (wire size, length, connections) in the B+ or ground results in a "voltage" difference, which generally equals noise.

Everything running to the battery posts is not necessary as long as all audio components access the same battery. For purposes of noise elimination, the key is to have the absolute lowest degree of resistance between all audio components. This is often best achieved by directing all grounds and supplies to common junction points closest to the amplifiers.    

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Dsingram

I said battery leads but meant off the power blocks downstream of the selector switch.. Thanks! Oh goody, I get to run another cable across the boat!  But hopefully it will fix me, thanks all!!  

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Dsingram

Sorry, last question.  I know I don't need a huge cable as the current is so low to the eq and head end... But want to fix it for good.  I am thinking shielded 14 gauge.. Is that about right or can I go 16?

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David
36 minutes ago, Dsingram said:

 

Shielded cable does nothing for you in this case. Just a 14ga + and a 14ga -. 14ga. is fine, 12ga. maximum.  

 

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Dsingram

Thanks all.  I ran the boat this weekend and the alternator whine is gone.  I still have a little hiss, but I can only hear it when the speaker is quiet... almost!!

Running the positive was what cured the problem.

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Stevo

You may want to lower your gains on the amps and see if that reduces the noise. Also the 420 has a jumper you can switch to help isolate the engine noise

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