Induced noise/Ground loop trouble shooting guide.

**Will Albers** · 07-18-2006, 01:49 PM

If it happens on head phones it is NOT, i repeat NOT, a ground loop between your sound card and amp. The ground loop isolater is not the solution.

You are getting a ground loop between your PC/Sound card and inverter. Ignore all other components. Use headphones as much as possible.

This is what I would try: Ground the cassis of the inverter to the same point you ground the PC. Ground the Chassis of the sound card and chassis of PC to the same point. Ground the USB cable (if possible) to the same point. If you still get popping through the HEADPHONES, i would bet its an issue of inverter quality. Look into a DC to DC power supply to solve your headaches.

There may not be an easy solution to the problem. Again, these components are never designed for automotive use. Its not that the devices are bad, just not designed for what you are trying to do.

**j0hn** · 07-18-2006, 03:01 PM

Thanks for pointing that out. I suppose I didn't think that through.

Now, since I am using a laptop in a docking station plugged into an inverter, I should just have to ground the inverter to the chassis, correct?

Components not designed for automotive use...what were they thinking?

**Will Albers** · 07-18-2006, 03:34 PM

Originally Posted by j0hn

Thanks for pointing that out. I suppose I didn't think that through.

Now, since I am using a laptop in a docking station plugged into an inverter, I should just have to ground the inverter to the chassis, correct?

Components not designed for automotive use...what were they thinking?

Carnetix make a 1900 DC-DC power supply. I would bet you can get it to work on your setup really well. It may eliminate a lot of your problems.

Now as far as your question goes, im not sure what you are asking. What i was implying is you want to ground the chassis of all of your components (The metal box surrounding the guts) to the same place where you ground the actual power flow. Its way overkill, but its a simple enough thing to do and can help out in these strange situations. If it works, start removing them and find out where it suddenly kicks back in. That was your problem source.

Anyways, check your power supply of the laptop. If its 19volts output or lower, you can usually modifiy the carnetix 1900 to power the unit perfectly, plus you get to eliminate the inverters. It will even give you shut down controller and 5v source! Look on the classified section to find em less than $100

Good luck

**p&gcustoms** · 07-18-2006, 09:43 PM

Originally Posted by j0hn

I did get a chance to try out the headphones and I get the same thing so it is still between the sound card and the amp. I will get a ground loop isolator and try it out. Anywhere local to get one of those or just order online?

yes me im on lawndale between wayside and telephone i could help u out with that prob

**soerenkroeger** · 07-19-2006, 05:11 PM

Hi Will

just wanted to thank you for that thread - it really helped me to eliminate the data-noise i had on my system - which was caused by bad ground cable and/or the stock grounding point was on a piece of metal, which was tacked to the rest of the car

The only noise i have left now is a little whinening where the frequency depends on the engine revs. But that might be my dc-dc inverter which isn't inverting any more (yeah i did a shortcut on the output *doh*) ...

Thanks - this was really the best explaination i have found on the internet so far :-)

Best regards,
Søren

**Wiredwrx** · 07-26-2006, 04:22 PM

Hello Will and everyone.

Hoping for some help.

Current setup:
M2-ATX
SV24
Using on board sound
Powring the some USB ports off the M2, some through the MB
Using AUX IN on crappy "Rampage" HU
High/constant power from battery to distribution blolck, all devices constant power from there.
Acc power from single sourcen all accessory power taken from the same point.
All ground itens grounded to the exact same point using same gauge of wire used for power.

I get some electrical noise from the computer. grounding the all metal case to the same ground point improved the situation.

But, I get heavy engine whine disconnected the computer from the headunit, and noise went away.

Checked the carputer with earphones, no noise. Used an Ipod thriugh the HU, no noise. Disconnected antenna from HU, no improvement. Grounded the chassis of the HU to the same ground point, no change.

It's gotta be in the patch cable between the catputer and the HU. Is there a more " proper" solution then a GLI?? Do you think I should try a balun or a choke first/also??

Any help is greatly appreciated, thanks in advance.

Michael

**RedGTiVR6** · 07-26-2006, 04:26 PM

So when you disconect the computer from the HU your noise goes away?

I hate to say it, but Rampage is not known for being even remotely high quality. If you've checked all your connects, all of your solder points are solid, and wires are not crossed, then I'd questions your RCA.

What kind of cable are you using? Is it shielded? Is it the Rampage quality RCA as well?

**Nomader** · 07-26-2006, 05:58 PM

hello.. good thread!!
I just installed everything.. and guess what. I am getting noise.. let me explain.
I have moved my head unit back in the trunk. by extending all the cables of the ISO connector all the way to the trunk. the HU works perfectly alone.. no problem there (by the way it is a veeery good Blaupunkt HU). Now I use the AUX in cable for blaupunkt which is not rca just a plain headphone jack that plugs directly into the soundcard..
I don't have noise when using headphones.
I don't have noise when using the HU alone.

so I guess the thing grounds through the Aux In cable right?
I had 2 noises.. one noise was constant.. it was there even when engine not running..(hard disk and mouse noises) the second was the whine which gets worse when i rev up..

iI used a good ground position..I tried to remove the ground cable from the ISO connector of the HU and ground the HU in the same ground with the PC...did not help a lot..
what i did and it actually removed the first noise was to place the HU on the metal case of my PC..that removed the hard disk nise by 95% and reduced the alternator whine by say 60%.. I stil heare that bird sing

any ideas how to remove it 100%??

I am using 4 AWG wires from the battery (for future expantions then 12 awg for the PC - just for 50 cm long) the ground is also 4 AWG and then it gets to 12 AWG (as the 4 AWG won't fit in the DSATX)

**Wiredwrx** · 07-26-2006, 08:06 PM

Originally Posted by Red GTi VR6

So when you disconect the computer from the HU your noise goes away?

I hate to say it, but Rampage is not known for being even remotely high quality. If you've checked all your connects, all of your solder points are solid, and wires are not crossed, then I'd questions your RCA.

What kind of cable are you using? Is it shielded? Is it the Rampage quality RCA as well?

Thanks for the response Red. I know Rampage is crap, but I didn't think it would cause this problem, and it was cheap.

The ONLY time there is noise is when they are connected together. Also, while it does get worse once the computer is started, even if it off, but has power and get, there is whine.

I am using a " patch cabe" between audio out of the carputer and aux in. It is a 3 conductor cable, and I am almosy certain it is shielded. Could be "rampage" quality. I have some "quality" rca's available, but not looking forward to all the gender changers and stuff like that.

Thanks
Michael