Ground Loop only when I take Faceplate off???

nobb · 09-09-2007, 12:13 AM

I was previously using the line level outputs on my headunit to connect to my amp and have had no problems. My speakers started distorting and upgraded to RCA cables instead of using the line levels to try to diagnose the problem (turns out it was not a cabling issue).

As long as I leave my faceplate on the headunit, there is no ground loop. But as soon as I take off the faceplate, I will get a slight buzz. I know for a fact that it is due to the RCA's because when I unplug them, the buzz is gone. I should also mention that the buzz seems to be the same frequency that emits from my ATX powersupply when it is connected to my inverter. No, I dont plan to go DC-DC anytime soon, so hopefully someone can give me some suggestions on why I am getting a buzz only when my faceplate is off. I am guessing the ATX psu is somehow interfering with my audio (never happened previously), but why? I also like the sound quality a bit better from using the RCA's, so I would prefer not having to downgrade to line level again. I also do not want to use ground loop isolators because I heard transformer based units will mess with the sound quality.

Its a slight annoyance, but maybe someone has some suggestions. Thanks.

2k1Toaster · 09-09-2007, 12:19 AM

Well your question of "where" the noise is coming from is apparent, and you meantioned it... inverter.

As to how to bandaid it, have you tried a bigger wire on your HU's ground?

Or trying the RCA to ground thing. I think you take 1 side and ground the shield the other you keep.

There may be more, those other than a GLI, those are the most popular options.

Also just to make sure, you do have your RCA's running in a different area than your power right?

nobb · 09-09-2007, 12:23 AM

Yes the RCA's are in a different area than power. My HU is also grounded to the chassis because of reports of Pioneer HU's blowing a microfuse if grounded to the radio harness.

Can you elaborate on the RCA to ground thing with the sheild? I am guessing you take the grounds on one side, connect them, then ground it? Which side is preferred to do this at? I am not sure if this would be a good idea in my case because I have a Pioneer HU. According to another forum, some users have blown a microfuse in their hu's due to the fact that their RCA ground was of a less resistance than the main ground on the hu. This would mean that the HU would ground itself through the RCA's and blowing the fuse.