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davidstan
07-03-2011, 04:59 PM
There are 4 ground posts in the back of my x2 close to the perko. It looks like there is one ground cable going to each of 3 posts and 4 cables going to the 4th post. 2 of those ground cables i traced back up to the 2 amps i run on my boat. Question is could the hissing i am getting from my speakers be from too many grounds on one post? I have separated the rca cables from the power cables to the point where they are hardly still in my boat. The ground at the amp that is producing the hissing looks good but i still reinstalled the ground after cleaning and inspecting. It is not a bad amp as it works great until i trigger the hissing with turning on any dash switch or decellarate the throttle. Anyone have an idea or have a similar issue with grounds?

Stutsman230
07-03-2011, 10:15 PM
Did you say that this has always been a problem? If it just started showing up there may have been a small order of grounds problem and as connections get corroded the voltage drop is getting bigger as others on this forum have stated.


The whine is probably caused by the "order of grounds" not the gauge of the wire. The ground wiring in order of connections should be as follows:

Motor wiring ground connects closest to the battery,
Next I would connect the gauges and any other motor system grounds,
Next are the power amps and finally the audio equipment such as head unit, radio, equalizer.

The basic idea is that you don't want any noisy grounds such as ignition or alternator to send current pulses through the most sensitive circuits. The reason for the amps to go before the head unit or radio is that the high amplifier current will modulate the sensitive circuit preamps etc and either create oscillation or distortion.

Always connect the highest current devices (least sensitive to noise) closer to the battery and the most sensitive farthest away from the battery. Replacing the wiring with welding cable will not fix a ground loop problem.

JimN
07-03-2011, 10:30 PM
There are 4 ground posts in the back of my x2 close to the perko. It looks like there is one ground cable going to each of 3 posts and 4 cables going to the 4th post. 2 of those ground cables i traced back up to the 2 amps i run on my boat. Question is could the hissing i am getting from my speakers be from too many grounds on one post? I have separated the rca cables from the power cables to the point where they are hardly still in my boat. The ground at the amp that is producing the hissing looks good but i still reinstalled the ground after cleaning and inspecting. It is not a bad amp as it works great until i trigger the hissing with turning on any dash switch or decellarate the throttle. Anyone have an idea or have a similar issue with grounds?

If the posts are on a metal strip, they could be dirty/corroded and any resistance on your ground and/or power circuit can increase the chance of having noise in the audio system.

If you would re-read the other noise thread, look for the post where I described how you should re-wire the ground to the head unit. This cures about 90% of the noise problems I have dealt with, and I dealt with a lot of them over 20 years working with 12V audio/security systems. If you measure more than about .1 Ohm from the head unit's case to the amplifier's ground terminal, it's too much and that's where your problem is. Look for the part about looping the head unit's ground wire to the stud on the back of the case and running a ground wire to the amplifier's ground terminal.

If you have a multi-meter, measure the resistance from the head unit's case to the battery ground post. Not the clamp, not the 4 studs, not any distribution blocks. ALL POSITIVE AND NEGATIVE CONNECTIONS SHOULD BE REFERENCED TO THE BATTERY POSTS. Measure from the battery posts to the first terminal (ring, spade, or other type- these are usually mistakenly called 'connectors'). If you see any resistance from the post to the metal or to the wire, it should be replaced. Work your way toward the amp- if you can measure more than about .1 Ohm from the battery post to the battery side of the fuse, it's too much. If you can measure more than .1 Ohm from the negative battery post to the negative terminal on the ground wire, it's too much and needs to be repaired.