Houston We Got a Hiss

[JBehrens]

So last trip I noticed a background high level hiss coming from the stereo while the boat was on. When stop the hiss went away so I didn't think much of it. Started doing some investigating and am finding that the hiss noise only occurs when anything to do with the stock electrical system is engaged (blower on, bilge on, engine start, etc). From what I can tell, the noise is somehow making it's way from the HU to the amp, with the RCA's disconnected and amp on there is no noise. Everything has common grounds and looks to be wired correctly so where should I go from here?

Thanks

 

[mark_m]

How short are the interconnects between the HU and the AMP?

Suggest starting with that link first. I have my HU connected to Jl800/8 with non special rca patch cord.

How is you amp powered? Did you run from battery/bus bar to amp with ? Gauge wire? Need more information about your setup please.

 

[JBehrens]

The RCA from HU to Amp is 3ft Knukonceptz Krystal twisted pair RCA 2ch x3

Setup is a Kenwood HU (KMR-M325BT) connected to the factory wiring harness, Amp is JL M600/6 with 3ft RCA to the HU, 4 gauge MESA 100% OFC wire for power and ground back to the battery. Battery has a BEP 2 battery switch (the basic one without DVSR), battery 1 and 2 have common ground both neg poles linked with 0 gauge jumper. Power to the amp is delivered from the battery switch with a 150amp house breaker.

 

[swatski]

The RCA from HU to Amp is 3ft Knukonceptz Krystal twisted pair RCA 2ch x3

Setup is a Kenwood HU (KMR-M325BT) connected to the factory wiring harness, Amp is JL M600/6 with 3ft RCA to the HU, 4 gauge MESA 100% OFC wire for power and ground back to the battery. Battery has a BEP 2 battery switch (the basic one without DVSR), battery 1 and 2 have common ground both neg poles linked with 0 gauge jumper. Power to the amp is delivered from the battery switch with a 150amp house breaker.

View attachment 97192

If you ground the HU to the amp ground wire, not factory harness, I bet you will remote 90% of the hiss if not all of it.

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[JBehrens]

If you ground the HU to the amp ground wire, not factory harness, I bet you will remote 90% of the hiss if not all of it.

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I shall give that a shot today, Thanks!

 

[JBehrens]

If you ground the HU to the amp ground wire, not factory harness, I bet you will remote 90% of the hiss if not all of it.

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Yep moving the ground to the amp made the hiss disappear. Finally have this thing sounding like it should. Thanks for all the help!

 

[swatski]

Yep moving the ground to the amp made the hiss disappear. Finally have this thing sounding like it should. Thanks for all the help!

View attachment 97245

BTW - that's @Mainah - for credit, just regurgitating his advice that worked for me and others (can't find the thread now). He keeps reminding us that boats are funny, you know - no chassis w/ ground...lol.

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[JBehrens]

BTW - that's @Mainah - for credit, just regurgitating his advice that worked for me and others (can't find the thread now). He keeps reminding us that boats are funny, you know - no chassis w/ ground...lol.

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Haha yep makes sense but still you would think that it would be fine because it all goes back to the same battery. At least that's my thought.