Grounding an amplifier

[brick75]

Looking to install an amplifier, and I'm wondering if there is a spot to connect the ground wire up under the dash? Pretty sure there is, but I'm not familiar enough with boat electronics to know where it would be. I'm sure I could trace a ground from the depth finder or some other device, but just want to be certain that I get to the right place and that it is designed to handle the grounding of an amplifier. Thanks for any insight.

 

[bruceb58]

Re: Grounding an amplifier

How much current does your amplifier draw? To be safe, and for electrical noise considerations, might be worth bringing it back straight to the battery.

 

[brick75]

Re: Grounding an amplifier

That's what I was originally planning to do until I read in the amp's manual to keep the ground wire at 24 inches or less. I think even with a front connection I'd end up at more like 5', but going all the way back to the engine would make it more like 18'. The amp isn't overly powerful, just 35w RMS x 4.

 

[seabob4]

Re: Grounding an amplifier

What I do on electronics installs is I run a separate hot and ground bus off the ones behind the helm, fed by 8GA. Then all power supplies to the electronics are fed from these two buses...

 

[bruceb58]

Re: Grounding an amplifier

I think even with a front connection I'd end up at more like 5', but going all the way back to the engine would make it more like 18'. The amp isn't overly powerful, just 35w RMS x 4.

Think about what you are saying for a second. If you tie into the the ground at the helm, you add 5' to the length of wire that is already running to the helm! Just because it is two different pieces of wire doesn't mean you have kept the ground down to 5'.

 

[RickJ6956]

Re: Grounding an amplifier

Brick,
Consider putting the amp near the battery. Run two shielded RCA's and a single 16-gauge from the head unit for audio signal and remote power.

Seabob, if the mains coming to the helm are 10 gauge, the 8 gauge isn't going to allow you to pull any more than the 10g can handle.

 

[Audio Greg]

Re: Grounding an amplifier

Brick,

If this is a new installation, your boat's manufacturer did not plan for the amplifier. Your amplifier manual tells you to keep the ground wire short because it is either an automotive amplifier, or the amplifier company based the amplifier on an automotive amp and did not correct this part of the manual.
Boats do not have the steel chassis car amplifiers use for ground. Further, boat manufactures do not over-size ground buss wiring "just in case" an owner might wish to add another high-current device (i.e.: amplifier).

Run ground back to the battery just like you do for power. Use the same AWG wire.

 

[seabob4]

Re: Grounding an amplifier

Brick,
Consider putting the amp near the battery. Run two shielded RCA's and a single 16-gauge from the head unit for audio signal and remote power.

Seabob, if the mains coming to the helm are 10 gauge, the 8 gauge isn't going to allow you to pull any more than the 10g can handle.

Rick,
You are correct. But I've benn an electrician at Wellcraft, Hydra-sports, Stamas, and Proline. The least I've used to feed the helm was 8GA. At Wellcraft, it was 6GA...

 

[seabob4]

Re: Grounding an amplifier

Here's a pic of the helm of a complete re-wire I just did on a Proline 18 Flats. Note the helm feeds, which are 8GA...

 

[brick75]

Re: Grounding an amplifier

Brick,

If this is a new installation, your boat's manufacturer did not plan for the amplifier. Your amplifier manual tells you to keep the ground wire short because it is either an automotive amplifier, or the amplifier company based the amplifier on an automotive amp and did not correct this part of the manual.
Boats do not have the steel chassis car amplifiers use for ground. Further, boat manufactures do not over-size ground buss wiring "just in case" an owner might wish to add another high-current device (i.e.: amplifier).

Run ground back to the battery just like you do for power. Use the same AWG wire.

Thanks Audio Greg. I guess that brings me to another question. The amp I was considering is in fact an "automotive" amp. I know using marine equipment is the better way to go, but I have a very dry location that it can be mounted, so I was hoping to save a little dough by going that route. Is there some other reason why an automotive amp cannot be used on a boat other than the moisture concern?

 

[Audio Greg]

Re: Grounding an amplifier

Brick,

Indeed, water is the concern. Bone dry is where your amp would like to operate. Even the marine amps will fail when they get wet. Just keep your wet gear (life jackets, etc.) out of the dry area to prevent extra humidity and/or condensation.

The "Marine" amps are supposed to have a conformal coating to help resist moisture. I read a post recently suggesting all head units now have the coating. That doesn't sound right to me. I guess only Taiwanese children on the assembly lines know for sure. Anyway, there is no other advantage to "Marine" amps over the "Automotive" amps.