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Discussion Starter #1
So I installed the PIE preamp to increase the level when running my XM receiver through the aux input on the front of the RF HU. Everything was fine until a few weeks later when I started hearing a very annoying, high pitched whine. So last night I took the amp's ground wire and tried grounding it to a different spot under the dash. Well, no matter where I stuck the wire I still had the whine. the funny thing is that without the ground wire connected the whine disappeared and the amp still works fine. So right now the ground wire is just hanging, not connected at all. Is grounding the amp absolutely necessary or can I just leave it the way it is now? I thought the amp wouldn't work at all without a proper grounding connection.
 

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No, the amp will not work without a proper ground. What you have shown is that it is getting a ground from somewhere else (probably through the AUX connector on the radio). The whine is likely the result of a ground loop (two ground points at different electrical potential), removing the ground wire to the amp 'opened' the loop removing the whine.

The ground wire to the amp is it's DC return, that wire needs to be connected because it is not a good thing to have the shield of an audio lead serve as a DC return. If the whine returns in that configuration then you need to work on isolating the audio leads to break the ground loop. This could require relocating the physical location of the audio leads or use of isolation transformers.
 

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Discussion Starter #3
So since I couldn't find a good place to ground the amp what are my options? Other than continuing to search for a good place to ground, that is. I'm sure eventually I find a spot that doesn't give me that whine but the length of the ground wire and the fact that it was getting dark limited me.
 

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Do you have a permanently installed satellite radio or is it a portable? If portable do you have a charger/power source for the device installed in the Titan? If you have a portable device power source or permanent satellite installed, try connecting the amp ground to the same location as that device.

Since the problem did not occur at initial install, but became apparent over time, then something has changed. It could be a relocated audio cable - try moving those around, or it could be a failure in one of the other devices (sat receiver or charger).

You could also try feeding a totally external source into the pre-amp such as a portable, battery powered audio device that is not connected to your truck in any way except the audio leads to the amp.
 

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Maybe try to ground at or near the same place that the cable shield connects to ground.

I noticed that the RF HU grounds at least three ways (1) via the mounting bracket (2) via the harness - which I believe goes to ground at a metal bracket located under the plastic skirt of the lower driver side dash and (3) via the antenna.
 

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Discussion Starter #6
bestatchess said:
Maybe try to ground at or near the same place that the cable shield connects to ground.

I noticed that the RF HU grounds at least three ways (1) via the mounting bracket (2) via the harness - which I believe goes to ground at a metal bracket located under the plastic skirt of the lower driver side dash and (3) via the antenna.

Bestatchess - My original grounding point was your #2 above ((2) via the harness - which I believe goes to ground at a metal bracket located under the plastic skirt of the lower driver side dash) so that point is out. I guess I could just splice some longer wire to the ground lead and keep trying different spots until I find something that works.
 
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