Ground Q/A sticky

question, is it ok to ground 3 amps (all 8 gauge all 2 feet long)to a distrabution block and ground it with 4 gauge also at 2 feet?i have 2 kickers 250.2 and a 350.2 and last but not least a sony mono amp at 800 wattts.

Yes this is fine to do. I will leave out the particulars on grounding for now. If you have specific questions or problems that arise post them up and they will be answered. Once we have compiled the info for the main grounding topic, go through your system again and address the issues that may be specific to your installation.

Hi guys. I recently had my system professionally installed. Cosmetically they did a great job. Unfortunately, i have an awful alternator whine.  I have only had the system running for 1 wk yet i cant stand to listen to it because of the noise!!! aaaaaaggggggggghhhhh!

Anyway, i did a few tests. im fairly certain (please speak up if im off base) that the ground loop is entering via the HU ground which is grounded up front through the original factory ground.  Im assuming this is through the wiring harness?? anyway ive isolated it to the HU ground because......

 1. I replaced the head unit (sony cdx c910) with new eclipse cd8443.  ground loop persists

 2. I patched my ipod into the eclipse via the AUX input.  same ground loop.

 3. i disconnected the eclipse rca output and directly patched my ipod into my line driver. The line driver normally takes the output of the HU via 18 inch RCA cable and converts it to balanced XLR outputs whihc is routed to the back into xover, amps, etc. After patching in my ipod (headphone out) , Viola! the alternator whine disappeared.

Am i correct in believing the HU ground is the cause of the ground loop.  The remainder of the system is grounded in the back (3 amps, xover, etc).  I know install rule 101 says to ground all compnents to a SINGLE spot.  I am assuming that this includes the HU. Nevertheless, i am extremely disappointed in my installer.   1000$ install and i have alternator whine??? 

So, i rescheduled to have the installer go back and run a ground cable from the HU to the back where the ground distribution block is located. 

So what do ya'll think??    I am well aware that car audio is frought with noise but i feel they should at least ground the system properly .  Did they follow standard install technique and i am being too demanding???   Is my HU ground the reason for the loop? Thank you for your input.

Btw, car = 1997 civic

hi rob! thanks for your help.!

yes, i have bypassed the line driver and the whine persisted.  also, the gains on the line driver and amplifiers are minimized.  i bypassed the line driver by plugging rca's directly from HU into xover. 

i could use the HU's xover and bypass the line driver and tube xover and patch an rca cable directly from the HU to amp, but havent pursued once noise disappeared swapping eclipse source for ipod soucre. i know the ipod is not part of the car's electrical circuit obviously, but the line driver, xover, and amps are connected to the electrical system; so am i wrong in assuming that they are not the source of the loop. since i 'removed' the HU from the signal chain, isnt this the culprit???

no, the installer did not check ground resistance.

This is just my opinion so don't take it for gospel, running a ground wire all the way to the back is impractiacal. The only thing that makes any sense here is that all grounds should be at the same potential, zero volts.

Yes, the factory wiring is rarely in any kind of shape to supply clean power to the HU, this is common.  Ground the HU to the body right about where the HU is, if you have to run a ground directly to the firewall or floor, that's fine. Also, bring 12 + directly from the battery, fused as always.

A muting plug is simply an RCA plug with the two conductors shorted together. Anyone can do this with a pig tail, by splicing the wiring with a crimp. Soldering the pins together is better.

Just remember: DO NOT CONNECT THE MUTING PLUGS TO THE OUTPUT!!! 

The only purpose of the muting plug is to zero the input signal at the line level INPUTS......It will short the output stages of the HU or whatever else, since it is indeed a shorted plug.