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  • odds of having ground noise?

    If I go the cheapest route, what are the odds of me having really irritating ground noise and would it be nearly impossible to fix?

    Right now I have an amd 900mhz, 8 gig 3.5" hd, 300 watt psu, and I'd be purchasing a 400 watt inerverter. I'd be power the front and back speakers with one amp, and powering my sub with another amp (will daisy chain the rca's). I have onboard sound on the via mobo.

    I do not have a case but I was going to make my own case out of sheet metal and mount it hidden somewhere.

    What concerns me is the 2 amps, the inverter, psu, and the onboard soundcard... What do you guys think?

    Oh yah I'm going to get a touchscreen lcd too, just haven't decided on which one yet, most of them can be hooked up directly to the battery?

  • #2
    there a few main points to remember, to help prevent "noise"

    -keep power cables as far away from your RCA's as possible. (by this, run them down opposite sides of the vehicle, take the seats out if it helps).
    -Ground you PC case (when you make it) and ensure all grouding points are making good contact
    -ensure you use the shortest ground possible, some people also find a "common" ground useful (by which ALL negative leads will ground to the same point)
    -because you are using two amps, run one larger set of cables big enough for both amps, then use a distribution block to power each amp from the larger cables, this prevents running several lengths of the same cable.
    -if necessary, install a ground loop isolator (helps reduce noise in a system)

    best of luck...
    Hilux Surf (4runner) install
    false floor in rear housing;
    4 channel amp
    600w cont. inverter.
    Also- DigitalWW 7VGA indash
    headunit for FM/AM,DVD,SVCD,CD,MP3
    P4 3.0 with low profile AGP card.
    4x4" speakers (splits) in factory locations
    BU-303 GPS

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    • #3
      Just like they said, its all in the wiring. Keep it clean, do it right, and you should have very little if any noise in your audio or video.
      -Drew Taylor
      2000 Grand Am GT PC

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      • #4
        Keep the actual inverter box away from the RCA cables as much as possible too. Supposedly those things put off a huge field of noise/interference. I'd like to recommend a PW-X series PSU from mini-box.com, however. They are about the price you're gonna be paying for a nice 400 watt inverter. Just run it without the ITPS. Or you could get an M1 psu, but I dont remember how much they are...
        CarPC install is starting to come along again...

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        • #5
          Thanks for the info guys... I understand all of that stuff about running power wires and such, I just wasn't sure about the computer/power inverter part of it and/if it was a big issue (moreso than common audio wiring/amplifiers)

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          • #6
            You need to make sure the ground is as good as possible, and the resistance is very low. This is critical. Ground noise / ground loops occur when the electronic device, such as the motherboard chooses the RCA shielding as the ground rather than your actual ground / DC - This could be because your ground is crap, your case is not grounded properly or well enough, or the distance through to ground is quicker/lower resistance through the RCA>amp>ground than the PSU>ground. You can use a ground loop isolator, they are pretty good at getting rid of a few other bits of noise too.
            Ford Focus MP3 : www.stevieg.org/carpc Blog Updated 29 January 2009!
            Car PC Status: Complete - Undergoing Software Redevelopment

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            • #7
              Oh using a DC>DC automobile PSU although not a magic want helps keep that route to ground as short as possible and makes sure the DC current that arrives at the MB is as clean as possible, as you might know the invertor is only generating a fake, square sine wave for AC from the DC power which is then converted back to DC by the domestic ATX psu. You can tell the crap sine wave by the 50hz humming noise appliances running off cheap invertors make.
              Ford Focus MP3 : www.stevieg.org/carpc Blog Updated 29 January 2009!
              Car PC Status: Complete - Undergoing Software Redevelopment

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              • #8
                So is a $50 inverter from wal-mart going to be causing problems?

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                • #9
                  I'm looking at this, http://www.mini-box.com/s.nl/ck.GJ6P...it.A/id.300/.f ...

                  Do I need anything else for power and will that work with my motherboard? Are there any serious consequences to not using a ITPS? It says it works with 12v... does that mean it won't work at 11.5v or 13v? The pw80 says it works at 11-30v...

                  My motherboard is a... k7vza ATX with a via kt133 chipset

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                  • #10
                    Originally posted by CornFlake340
                    I'm looking at this, http://www.mini-box.com/s.nl/ck.GJ6P...it.A/id.300/.f ...

                    Do I need anything else for power and will that work with my motherboard? Are there any serious consequences to not using a ITPS? It says it works with 12v... does that mean it won't work at 11.5v or 13v? The pw80 says it works at 11-30v...

                    My motherboard is a... k7vza ATX with a via kt133 chipset
                    Yeah you would need that + ITPS. It won't survive engine cranking though. You might be better with that + carnetix.com PSU.

                    LOL @Wal-mart we don't have that in this country, I couldn't comment how good they are

                    Steve
                    Ford Focus MP3 : www.stevieg.org/carpc Blog Updated 29 January 2009!
                    Car PC Status: Complete - Undergoing Software Redevelopment

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                    • #11
                      Stevie, thanks for the explanation of what causes ground noise.

                      If youre using an inverter, you would want to ground it to the same point where your amp is grounded. But what do you guys mean by grounding the case??

                      Be careful with those PW psu's. I havent looked at them in a while, but the PW60/70 seemed alright, while the others appeared to overstate their output.

                      Wow, no Wal-Mart in UK!! Just wait a week or two...
                      My first carPC!
                      MP3/CD player
                      Celeron 633MHz - 10GB Seagate - 64MB PC100 - Win XP

                      Soon to actually find its way into the car!

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                      • #12
                        Grounding the case = running a wire (of suitable gauge) from the metal case to the car's chasis. Of course you will probably want the same grounding point for all of your devices.

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                        • #13
                          Is this inverter suitable? http://www.walmart.com/catalog/produ...uct_id=1818511

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                          • #14
                            Seems a little bit on the high side ($'s) even for Walmart but should be fine for wattage. It's pretty much hit or miss though if you get one that can survive cranking.
                            Rick S.

                            XP Pro SP2, Soyo P4RC350 MB, Nvidia FX5200, 320W PS, Inverter & uSDC20D, 2.4GHz CeleronD320, 512MB DDR, 30GB 3.5", Pioneer 106s Slot DVD, Linksys WMP54G WiFi, Lilliput 7" & 4" TFT LCD, Zippy EL610 Keyboard, Touchpad, Garmin GPS V

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                            • #15
                              We have Wal-Mart kinda


                              Are you sure you want to go down the invertor route, though? Always cheaper to start out on the right foot.
                              Ford Focus MP3 : www.stevieg.org/carpc Blog Updated 29 January 2009!
                              Car PC Status: Complete - Undergoing Software Redevelopment

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