Thread: Hard audio quality problem: Noise / Ground loop?

Have you tried grounding EVERYTHING (HU, computer, amp) to the same point?

As by hooking the sound into the amp directly got rid of the noise, there is a ground loop between the HU and the carputer/amp.

By grounding all my equipment to the same point, I was able to remove all the noise when I used a HU. Or, you could just try a wire from the casing of the HU to the ground for the amp/carputer


Garry

Originally Posted by Confused

Have you tried grounding EVERYTHING (HU, computer, amp) to the same point?

Exactly... your problem is that you have two different ground points... the amp hooked up to the battery and the comp hooked up to the chassis... Hook up both the amp and the comp to the same ground point on the chassis and not to the battery... ALL your ground should be hooked up to the chassis and nothing else

The thing that I don't get about ground loop isolator is that they say it is used to isolate problems where the devices are not properly grounded.

I bought some ferrite chokes and ground loop isolators today, but I don't understand why I need these if everything is, to the best of my knowledge, properly grounded.

I have all of my devices grounded as perfectly as I know how, and I still get a noise that follows the engine RPMs (I am assuming the noise is coming directly from the alternator).

Here is my wiring diagram:

I should update that drawing to show that the direct connection to the battery is not really there.

All devices are truely grounded to the chassis (not directly to the battery).
In fact, I have two power distribution blocks.
1) +: connects to the battery
2) -: connects to the chassis near the equipment
Every device I have has [more or less] a direct wiring (according to my schematic above) to both distribution blocks.
The amp is not shown in the above diagram, but it's + and - also go through the distribution blocks.

I haven't yet determined the precise recipient of the noise.
I don't know if:
1) The PC is receiving the noise and sending it to the amp's line in
2) The amp is receiving the noise and amplifying it
I will look in to this this weekend.

I just thought: maybe the noise is coming through my amplifier's ACC/power-on input?

Any other ideas where my loop may be?

Pv

Originally Posted by Confused

By grounding all my equipment to the same point, I was able to remove all the noise when I used a HU. Or, you could just try a wire from the casing of the HU to the ground for the amp/carputer


Garry

Hi Garry,

Does this mean if all the equipment is grounded to the same point, it doesn't matter where the positive is connected? I think this is where the problem is by many installers hooking up a HU with AUX IN. Even if the Amp/CarPC has all a common grounding point, the HU usually has another ground because of the ISO connectors.