Audio system problebms/ how to ground amp

[Iceman Yella]

I put my car stereo cd player and amp sub hook up in my boat, when the boat is running I get bad distortion and can not hear any thing so I turn off the radio when the boat motor is running. I have one amp grounded to the battery and another one for the sub to the engine block. WHat is the best way to ground all of this and why am i getting distortion when the motor is running?

 

[Splat]

Re: Audio system problebms/ how to ground amp

It should all be grounded to the battery. The interferance you hearing is ignition noise from bad shielding. First isolate if your hearing it from the radio, or if the amp is pickng it up.

You can then try installing a inline noise supressor on the power wire to which is picking up the noise.

You don't have something goofy like your amp mounted in your engine compartment near the ignition coil do you?

You could even try switching to a sparkplug with a resistor, if they make one compatable with your engine.

Bill

 

[Daley]

Re: Audio system problebms/ how to ground amp

Splat's right - ground everything to the battery. What's happening here is you've introduced a "ground loop", where the ground circuit will gravel from the negative post of the battery to the one device, through the shielding on the signal cables to the other device, down to the ground you have on the block and back to the battery with the engine-ground. That in itself is a huge factor. His other point about having stuff near "noisy" electronics (IGN coils, etc.) is also spot-on.

I used to be a licensed car-audio guy, and even the challenges in a METAL vehicle were enormous - fiberglass/wood boats just add to the complexity. Save yourself the hassle (and enjoy your investments) - use a COMMON ground. You'll likely find that a noise-suppressor of any sort is unnecessary if everything else is right.

 

[NHGuy]

Re: Audio system problebms/ how to ground amp

I hate it when my ground gravels!

 

[RickJ6956]

Re: Audio system problebms/ how to ground amp

Did you splice or change the RCA cable that provides signal from the head unit to the amp? This cable must be shielded, and if it's spliced the shield must be intact for the entire length of the cable.

The shield is a braid or foil that wraps around (but does not connect to) the center conductor inside the cable jacket.

 

[Iceman Yella]

Re: Audio system problebms/ how to ground amp

Alright thanks for the info, so I should not ground the amp to the engine block? Both amps are mounted in the engine area of my 21 Scarab, they are are on opposite ends of the engine compartment. I also ran my rca cables next to one of the power wires and I know that could cause problems.
do you think I need to replace my voltage regulator?

 

[Daley]

Re: Audio system problebms/ how to ground amp

Before you replace anything, make sure your wire-routes are good (get 'em away from stuff that would induce noise), and yeah - ground directly to the battery (assuming that's where the radio's grounded).

That way your ground won't gravel and NHguy won't have to call me out on my stupid spelling mistakes