Is the amp at fault?

**Will Albers** · 06-26-2006, 07:13 AM

Well thats your first issue. You have a ground differential between the PC and one of the amps. They need to be grounded to the same point.

A test speaker allows you to cut out the possibility that the noise is picked up through the spekaer wires/crossovers, etc. A test speaker is any old speaker witha little bit of wire attached that you plug into the amp output. If you hear noise with your normal speakers, but not when you disconnect them and plug in your test speaker, then the noise is not the amplifier.

I think your first issue is you need to ground the amps to the same point

**Tim Lake** · 06-26-2006, 08:23 AM

Ok, I guess I'll have to tear the car apart this weekend

Does everything (carnetix unit, head unit, crossover and amps) need to be grounded to the same place?
Do I need to ground the PC chassis in some way?

**Will Albers** · 06-26-2006, 09:44 AM

did you read my sticky!?

Yes, you want everything grounded to the same spot if possible. It cuts down on ground loops.

Yes, it cant hurt to ground the PC chassis as well

**parksgm** · 06-26-2006, 09:52 AM

Originally Posted by Will Albers

Yes, you want everything grounded to the same spot if possible. It cuts down on ground loops.

Yes, it cant hurt to ground the PC chassis as well

...and another thing...it's nice to use the same size and length of wire from each component to the ground to minimize differences in resistance from wires. But grounding to the same point is the first, best, step.

Also, there's a great FAQ in the ...wait for it... FAQ section on this, IIRC.

**Tim Lake** · 06-26-2006, 10:50 AM

Ok, I just re-read it!
So I'll rip the trim out, get some good thick wire and earth EVERYTHING to the same (good) ground point?
Is the battery the best idea or would it be better to go to the car chassis?
Are these the things I should be earthing:
Head unit/screen
Computer chassis
Startup/shutdown controller
Active crossover
Component amp
Mono amp

One more thing. Does it matter if I have to run quite a long length of wire in order to earth things to the same place or will using good wire avoid any problems?

**Shadow** · 06-26-2006, 04:52 PM

DO NOT RUN EVERYTHING TO THE SAME BOLT IF THEY'RE NOT WITHIN 2 FEET OF EACH OTHER.

Now that that's out of the way. Ground everything as close to the component as possible and use the same ground plane. In your car it's probably going to be best to use the floorpan/trunk floor for your grounding point. Your shutdown and carputer chassis need to be grounded to the same exact point. Everything else just ground near where the component is, but to the same plane.

**Tim Lake** · 06-26-2006, 06:02 PM

What is a plane (apart from the winged wright brothers invention)

**Will Albers** · 06-26-2006, 08:13 PM

In my car I have the amps and PC close to each other. I use a distribution block where my 8 gauge grounds all enter the block and a single 4 gauge wire comes out of the block to the grounding point.

Id guess your amps, crossovers and PC all fall close enough where you could do this. Your radio is far enough away where you need to ground this to a seperate place.

Some people run a ground wire back to the battery but its overkill. As long as you are careful about making your grounds overkill, you are usually ok.

Keep your amps close together and ground them at the same point. When thats done tell us if you still have noise.

**Will Albers** · 06-26-2006, 08:14 PM

Originally Posted by Shadow

DO NOT RUN EVERYTHING TO THE SAME BOLT IF THEY'RE NOT WITHIN 2 FEET OF EACH OTHER.

Why?

**Shadow** · 06-26-2006, 08:44 PM

Because long ground wires pick up more noise than short ones.

An electrical plane (think geometry, not aeronautics) is a solid surface that's electrically connected to another source. In cars usually the floorpan is the biggest single sheet of metal and it often runs from the firewall to the rear bumper.

Did you scrape the paint off of where you grounded everything?