Ground Q/A sticky

I'm having a problem with my LOC, i was getting a bit of static type noise through the speakers. I checked the manual and it said when this happens to hook up a ground wire to the chasis of the car. So I did that and now you can hear engine noise through the speakers, it is much worse! It happens even if I just hook it onto another wire that is a ground.

Is this what a ground loop isolator is for???

they are adjustable, they only output 2 volts at max and are at about 3/4 setting. The static seems to come and go now, sometimes at no volume I can hear it and sometimes I cant...

it's comming from all of the speakers, they are all aftermarket. Boston Acoustics FX93 and Phoenix gold tantrum 5.25"

Let me try that again...

Okay, here goes.  I don't think it is a ground problem, but maybe: 

I have a noise problem with a new HU.  Equipment involved:

2003 Hyundai Santa Fe GLS 3.5L

Currently I haven’t even connected the HU to the PA275 and sub.  That amp and sub are wired up but there are no patch cables running from the HU to that amp. 

The noise is not something I have run into before.  It occurs only when the engine is running and sounds like a “popping” or “ticking” ignition sound, but the “ticking” does not increase frequency or pitch as the engine RPMs increase.  It doesn’t sound like alternator whine.  It sounds like ignition noise, but I would have expected that to vary with engine speed. 

Anyway.  It does not get louder as the head unit’s volume is turned up.  My amp gains are all the way down.  The noise is there whether listening to the radio or CD.  The power and signal wires are run separately.  All accessorires are turned off (heat, A/C, etc…)

The odd thing I didn’t expect is that the noise occurs only on the RCA outputs.  The rear speakers are running directly off the HU and there is no noise.  I connected a LOC to the front speaker outputs and ran that into the amp and there is no noise.  Is there an obvious (but not to me) reason that there is noise on the RCA outputs, but not the speaker outputs?

I have tried:

Muting plugs on the amp – No noise  (This essnetally rules out the amp, x-overs, & speakers; correct?)

Noise occurs on front and rear RCA outputs. 

So any ideas?  I could use a couple.  Is there an internal problem with the HU?  I’ve grounded it to the same block as the amps, and the amps produce no noise.  The power wire has a factory installed choke coil integrated with the fuse holder.

The unit was purchased from Crutchfield and since I am past my 30 day free return period, I’m pretty much stuck with this unit.  I’ll call their tech support (which has been good in the past), but I’ll take all the help I can get.

As you would expect, I am a bit demoralized.  I’m no pro installer, but I’ve done this enough times that I never give doing the install a second thought.  I’ve dealt with ignition noise and alt whine before, but this is different and I’m rapidly running out of ideas.

I'm solving DEH-860MP alternator noise problem dropping 10db more.

By connecting RCA ground to main ground.

But it still there which I never have before with my old KEH-8650,

Though now it's much acceptable.

They say 33000uF or 47000uF capacitors might help in Taiwan's forum.

I will try if I can get them.

Hi finally I drop more by going battery power through a big filter coil which was sold in DIY store.

And drop a little by paralle a 50000uF capacitor.

So RCA grounding drop 90%, power filter drop 8%, capacitor drop 1% & I have ~1% WN.

I might leave this unit along & wait for my CDA-9855 which was shipped yesterday.

Dang it.  It's related to the PA2150 amp.

For the hell of it, I ran the HU into the PA275 and hooked up a spare full range speaker - no noise.  I had planned on shifting the front speakers to the PA275 eventually; so this just gave the incentive to do it sooner rather than later.  Everything is wired up in the front through the PA275 now and it sounds great.

Now I have to find out what is going on with the other amp.  Why no noise except when connected to the HU; a ground problem on the amp's RCA inputs? 

I'll see what I can find out.