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40oz

getting a good ground

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40oz

Having some engine noise come through my tower speakers only when the boat is on. From all the research that i have done, it is a bad ground issue. My question is where do i get a good ground on a boat? I thought about getting the ground straight from the battery, but remebered from my car stereo days that the ground wire should not be longer than 18". Should i just relocate the battery closer to the amp?

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Earmark Marine

The best grounding point for you is at the battery. If the amplifier is farther away then you simply increase the wire gauge to match the current draw times the distance.

There are always sources of noise present on a boat. But normally they do not have a free path into the audio system.

Your most important reference is between all the components in the audio signal path. This means that it is critically important that ALL audio electronics share the identical ground point.

Normally you could ground the source electronics at the battery terminal where the amplifier(s) are also grounded...when the amplifiers are in close proximity to the battery. However, when distance separates the battery and amplifier, then it is usually more important to ground the source electronics as close as possible to the amplifier primary ground terminal.

Use the same logic for the B+ supply also.

The second most common cause for noise is wide open amplifier input gains.

This is the time of year that aging batteries begin to reveal themselves and when shock and vibration begin to tale a toll on the terminations/connections.

David

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40oz

Thanks for the response David!

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Brianinpdx

Jim - I'd agree with the comment above about grounding to the battery. The most common reason for this is very simple. The CD player is grounded to a different point than the amplifiers or other electronics. What your hearing is the difference in ground potential between the devices. Eliminate the differential and you've eliminated the audible engine noise

In my experience, the second most common cause for engine noise is a EQ's in the signal path, that does not share the same ground as the other devices.. This issue comes up a lot when they are wired into the helm and grounded in that proximity.

I would Respectfully point out, amplifier gains do not cause noise. They amplifier it. Most amplifier designs of today do a very good job of isolating the circuitry internally and that protects against this issue. I would agree, Turning amplifier gains down to a reasonable point is always a good practice as it will eliminate the inherent hisssssss you hear in many systems. Separate issue tho completely.

If your engine noise doesn't go away after home-running all your grounds to the battery post up and we'll offer a few more detailed check list options for you.

-Brian

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MLA

In my experience, 9 out of 10 times, these types of noises are not related to where the head-unit and amps are grounded, but rather where the head-unit's yellow B+ and amps are obtaining there B+. Unless someone has done a custom install with a stand-alone battery bank for the stereo, then all batteries and electronics will actually be sharing the same ground plane. If not, then the batteries will not charge and components will not operate.

The source of the noise is a result of the amps "seeing" X voltage level from battery B and the head-unit "seeing" Y voltage level from battery A. When you have a difference of potential, the battery voltage tries to equalize. They do this between the only link between the head-unit and amps........the RCA cable. So this is where the noise enters then system, gets amplified and reproduced by the speakers. You can split hairs on terminology, but when the gains are too hot, you can have an unwanted hiss omitting from the speakers. The more efficient they are, the more noticeable it is.

With that said. Its always best to take the amps B+ and ground directly to the battery bank, simply due to their current draw. Its always a good practice to relocate the head-unit's GND and B+ either directly to the stereo bank, distribution blocks or amp lugs, depending which is closer and a cleaner/shorter run. This goes for EQ's, SAT receivers, MP3 chargers, etc. This is the absolute best way to prevent the unwanted noise.

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