Thread: The Most Incredibly Un-killable Ground Noise ever...

Thanks for your help and time Insane, I truly appreciate it.

Ok, before reading your latest post, I spent a good amount of time in the car troubleshooting last night. You're definitely right that the Tio's are the culprit, and I agree with your assessment of double-amplifying the noise.

Now, further to that point, I've also figured out this is definitely NOT a ground issue. How? I powered the Tio's with a desktop ATX PSU plugged into regular AC power, and the noise still persists! All that crazy work trying to find a good ground for the Tio's and that was never the issue!

So, this tells me that it's an EMI/RFI issue... the Tio's are picking up noise from the PC. I would have thought they would be better shielded though since they are made to be installed INSIDE PC's!

Anyway, back to your point Insane - I would LOVE to completely eliminate the Tio's from the mix, I think my issues would disappear. The problem is, my audio would disappear too. I have a Dynaudio amp with DSP in my car (sounds INCREDIBLE and I don't want to lose it), but this amp (and all VW premium amps) requires high-level inputs to turn it on. That's the entire reason I had to get the Tio's to begin with. VW is a strange breed of car, and there is no ACC going to this amp, and it only turns on when it senses a strong-enough audio signal. The Tio's are low-wattage amps so they fit the bill perfectly, but they are creating this noise. So as much as I've always wanted to do your suggestion #1, my amp won't turn on with the audio coming straight from the sound card. It needs a boost.

Now, what I don't know, (and no one from VW seems to know either!) is if the amp requires a certain voltage, or a certain audio level to turn on? If the answer is voltage, I could just get a line driver, put it in between the Pc soundcard and the amp, and hopefully that would be the answer!

In any case, I feel like I'm closer knowing that it's the Tio's and not a ground issue. My next step is to definitely eliminate the Tio's from the mix and see what I can do to get the signal from my soundcard to turn on my amp. My soundcard is an Auzentech X-Fi, so the quality is definitely there! I didn't skimp in the soundcard dept.

More to come! Thanks!

just a quick thought, you may have allready mentioned this, or someone else might have.


what AWG wire are you using between the neg on the batter to ground? alot of cars i've seen use this really whimpy wire.

on one (non-carpc) install i helped with, it was the source of the ground loop, we replaced the ground wire with a 2/0 and the ground loop went away.


one other thing i've done personally, was ground the computer case. that made one HELL of a difference in ground loop noise

the audio that would normally feed the dynaudio... its not by chance a balanced input is it?

feeding an unbalanced signal (generic pc outs) into a balanced device often causes noise, i had to buy balancing gear for a project i did a while back because of that... (tho i was expecting to have to buy it)

do you have a model number of the dsp/dynaudio device?

@Insane: I originally had a HU in the mix to turn-on and get high-level inputs to the amp. It just muddied up my sound too much. I've since re-done the whole PC (I used to use a laptop, and wanted more expandibility) and ditched the HU altogether. I haven't seen any type of aftermarket kit available to do what I need. I'm not surprised though since VW is probably the only automaker with an amp that requires high-level inputs. And as far as VW techs go, they're clueless, at least at the two dealerships near me. I do plan to talk to some car audio shops though. I'd be willing to bet though that even the car audio shops haven't dealt with this amp b/c they probably always install a new aftermarket amp. People who opted for the Dynaudio pkg in their VW probably don't go wanting to get an aftermarket system installed

@fisch: I am using 4 gauge for MOST of the run. It does go into a smaller gauge when it gets close to the PSU. I'll try running 4 gauge for the entire run just to be sure. Also, I have definitely grounded the chassis of the pc case! I read that one awhile back and made sure to do that. My only question is whether I've grounded it at a good place on the case? The case is mostly aluminum. I have it grounded at a point near one of the PCI slots. Where do you ground your case? Is aluminum a sufficient ground material? I do have it screwed in using the PCI screw at an empty slot.

@Woofnstuff: honestly I don't know if it's balanced or not. I'd have to measure the output of the stock headunit, which I've wanted to do, but it's near impossible because the wire cluster that connects to the headunit has all the wires together (power, speakers, ground, etc) in one big plastic connector. So the only way to get power to the stock headunit means also blocking access to the speaker outputs on it (meaning I can't get to the speaker outputs to test their output if I want there to be power to the HU!) And again, asking these questions to anyone at VW warrants a blank stare. I don't know the model number of the Dynaudio amp. It came stock with the car so I only know the VW part #. I've taken it out and examined it, and the VW part # is the only thing written on it.

So anyway, last night I picked up a line driver (JL Audio CL-RLC) to see if I could get the amp to turn on with just a voltage boost from the PC soundcard output (my soundcard already claims a 5V output, but it's truly more like 2.) I tried this b/c from what I read here...

http://www.mp3car.com/vbulletin/faq-...nsoon-amp.html

... it seemed to me that these VW amps just need 5v to turn on (even though it's Monsoon vs. Dyaudio, I thought maybe the same concept). The line driver I bought claims 7.5V RMS output so I thought maybe it'll do the trick. Long story short, nothing. It would not turn the amp on. I'll be returning it today. Bummer.

At this point, I'm willing to get a small proper car amplifier that will turn on the amp for me but hopefully be better built so as to not pick up noise. I love the size and convenience of the Tio's. but they aren't doing the trick for me.

Any suggestions on such an amp? It would have to be at least 2 channels in/4 channels out.

Thanks again for trying to help me out!

Just bought a small 4-ch Kenwood amp. I'll hook it up tonight and report back tomorrow. I hope this works and doesn't just give me the same noise the Tio's give me...

When you connect the GLI you stop the dc pass from your amplifier (TIO) to your car amplifier, that's why your amplifier turns off.

Looking at http://www.mp3car.com/vbulletin/faq-...nsoon-amp.html
you see, the sound level is not important to turn on the amplifier, what is importar is the dc level of the signal.

The DC level of a line out of a sound card is 0V, so it's not enought to turn on the amplifier, the dc level of a balanced output (BTL) of a radio-cd or the TIO is normally 6V, enough to turn on the amp. The level of AC (audio), makes no difference in turning on the amplifier, it affects only the max power output you will get from your power amp.

The noise you have will be originated by cascading the two power amp, a little noise in the output of the TIO will be superamplified by the second amplifier, muting all soundcard unused inputs will help, can you draw a detailed schematic with your current audio signal wiring, from pc to power amp?.

I suggest you to remove the tio and build the schematic presented in the link:
http://www.mp3car.com/vbulletin/faq-...nsoon-amp.html.

This circuit is a simple mixer that uses the GLI and a regulador to add a DC level of 6V to your sound card output.

Hey Visenri,

Thanks for jumping on board my mess of a noise issue!

Are you sure that all soundcards output that 0V level? This the soundcard I have, which claims a 5V rms output... (scroll to "Specs" at the bottom of the page)

http://www.auzentech.com/site/products/x-fi_prelude.php

Awhile back when I first started my car pc hobby, I built myself one of those 6v boxes to turn on my amp, and yes, it does work. Problem I had with it back then is the volume level I would get out of it was way too low when I came straight out of the soundcard into the amp. BUT, that was a soundcard of significantly lower quality than the Prelude so maybe the one I have now would produce different results.

In any case, I agree with you that I have to get rid of the Tio's, and I definitely understand yours and Insane's explanation of cascading the noise through two amps. One thing on that note though... when I was using a HU to turn on and drive my Dynaudio amp, I did not have any such noise. But I got rid of the HU b/c it made the sound muddy and blah.

Perhaps what I need is a good quality head unit that does not color the sound at all, and has a function where I can use only its power amp section. Does such a HU exist?

On a side note, the Kenwood amp I bought would not turn on my Dynaudio amp??? I basically put the Kenwood in place of the Tio's. There has to be something wrong with it... unless the level I'm sending to the KW input from my soundcard is too low. But the manual says it takes a range of 0.2V - 5.0V. Surely my soundcard can't be putting out less than 0.2V when it claims 5.0V!! Anyway, the Kenwood is probably not the answer anyway.

I just spent another 2 hours out there troubleshooting. I feel so defeated. I ran the pc ground to a new ground point just to be sure... I sanded down to bare metal and tapped right into the body of the car. No improvement in the noise. What would happen if I ran the pc ground wire to the ground wire up front that the LCD screen is connected to (which is the ground wire of the car's radio cluster)? Too long a ground wire? Seems it would definitely be at the same potential as the battery, but would the run be too long?

And one final question to add to the other 3: Would a power line noise filter on the 12V from the battery help my issue?