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Car Computer Install: Noise In The System

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  • Car Computer Install: Noise In The System

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    Sean discusses problems with noise in the system and ways to eliminate them.
    Have a product you would like to sell on the mp3Car Store? PM me for more information.

    Have a car computer question? Ask me by emailing the store.

  • #2
    just remember that ground loop isolators and direct-to-battery grounding are not always the only options. you can also try grounding to different points in the car, or, if everything is grounded to multiple points, connect everything to a single point. or connect a length of wire from the outer portion of the rca cable to the ground cable.


    unwanted noise in a sound system is usually the result of what is called a difference in ground potential-- which basically means that some devices have a easier path back to the battery then other devices. the entire idea is to get everything onto the same ground potential, which usually will correct the issue.


    there are tons of different solutions to ground loops and unwanted noise, so if you happen to have a particularly annoying one, i suggest searching sites like realmofexcursion.com, or diymobileaudio.com, or the12volt.com. all those sites specifically cater to car audio systems, and will have tons of info on ground loops and the previous solutions that people have used to correct them.
    My OLD 2001 Mitsubishi Eclipse GT:
    "The Project That Never Ended, until it did"


    next project? subaru brz
    carpc undecided

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    • #3
      Or simply do it by standards like AES48. That should guarantee no noise not only from ground loops but from external interferences (neon lights, RFI, etc..) as well. Long story short... balanced lines with shield grounded to chassis at both ends of twisted pair cables.

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      • #4
        Did you try doing the big 3 upgrade? Maybe your chassis was not grounded properly to the battery?

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        • #5
          hey guys,

          i couldnt contain myself on this post i really couldn't..this is a nissan altima. not some S**tty demestic pile. the grounds in the car are fine, slappy didnt ground it to the chassis like said,
          he used a factory bolt >i.e. seat belt or spare tire nut. 101 of grounding in a car. dont uses factory anything. i will even scan the beginners guide from the MECP book about this..

          second .the paint was not scraped down to metal.(from what was shown)

          and then ground loop iso's!!!! really? come on.

          this really twist my nipples

          only because, how can someone who doesnt know much about cars, teach other people how to do things in there cars.
          this is the blind leading the blind man.
          you sir are the reason people have a bad taste in there mouth about real installers.

          I am sorry for the rant! but come on ...

          Comment


          • #6
            Originally posted by Zerohour2100 View Post
            i couldnt contain myself on this post i really couldn't..this is a nissan altima. not some S**tty demestic pile.
            reality check-- nearly all mass produced vehicles in the last 20 years, regardless of the make, are spot welded. and spot welds are not always consistent in their mating of the two panels. this is the issue at hand. i don't care if it's a vw, mercedes, mitsubishi or chevy, they all do that the same way, so that argument lacks substance.

            Originally posted by Zerohour2100 View Post
            the grounds in the car are fine, slappy didnt ground it to the chassis like said,
            he used a factory bolt >i.e. seat belt or spare tire nut. 101 of grounding in a car. dont uses factory anything. i will even scan the beginners guide from the MECP book about this..

            second .the paint was not scraped down to metal.(from what was shown)
            99% if the time, all the extra stuff like sanding the paint off, and using a non-factory ground point is not needed. i know of plenty of trouble-free sound system installs that used a factory bolt, and never sanded anything. but once you have a issue with a ground loop, these are some of the first things to check.

            Originally posted by Zerohour2100 View Post
            only because, how can someone who doesnt know much about cars, teach other people how to do things in there cars.
            this is the blind leading the blind man.
            4 years ago, i knew how to click a mouse, and open my email. now i use a carpc every day, and have modded my car electrically in ways i barely imagined 4 years ago.
            everything is a learning process. i think sean knows more then he shows in this series..(remember, this is part of a introduction to carpc series, not a advanced tech doument)

            Originally posted by Zerohour2100 View Post
            you sir are the reason people have a bad taste in there mouth about real installers.

            I am sorry for the rant! but come on ...
            and you leave a bad taste in my mouth. he never claims to be a real installer, that he knows all of it, or has all the answers. and any intelligent person will do the same. it is impossible to know it all. this forum is based on a hobby-ist activity, and as such, some of the installs are crude, or not up to what a 'pro' shop would do. the video series is meant to be a starting guide to new members on what it takes to install a carpc. if you don't like the series, you should make your own 'correct' version. i think they did a great job covering all the different aspects of the build, and showing the different ways of doing things. is it the way i do things? no. but i don't want to make a video.
            My OLD 2001 Mitsubishi Eclipse GT:
            "The Project That Never Ended, until it did"


            next project? subaru brz
            carpc undecided

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            • #7
              Originally posted by protias
              DELETED BY MOD
              Comments like that are not appreciated on this board...
              Last edited by 2k1Toaster; 04-30-2012, 11:07 AM.
              "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
              RevFE
              My Shop

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              • #8
                This thread has been cleansed. Please keep the discussion to the topic at hand.

                If you would like to debate domestic vs. imported vehicle design and quality, feel free to do so in the Off Topic section found here: http://www.mp3car.com/off-topic/
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                • #9
                  Good example of troubleshooting. Sometimes things just don't go the way you plan them and you have to recover with some intelligent afterthought.

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                  • #10
                    Wanted to see if someone could tell me why it would it would a be a bad idea to run a ground wire from the battery to the trunk (like the video showed.)
                    You don't hear about doing that often. I heard it a few times but not as often as I thought you should.

                    Granted I am a noob to car audio installs (the right way) LOL. As a noob it makes common sense to me to run a seperate ground to eliminate all the grounding problems that can come up. I have not done it but always thought about doing it that way.


                    Besides overkill, not necessary if done right etc. Is there any other major concern for running a seperate ground?
                    I know there is also a possibility that a new ground loop can come up or still be there but it seems like 99% of the time it should fix it.

                    Any ideas?

                    Thanks

                    Comment


                    • #11
                      the main issue with doing it that way is the extra cost of cabling. it's really not the 'wrong' way, just not as cost effective as using a short length of wire to a solid chassis point.



                      while sean's setup will work fine with equally-gauged wires, it is also important to run at least 1 gauge larger(thicker wire) for the ground when using this method to try to reduce the resistance on the devices at the end of the wires.
                      My OLD 2001 Mitsubishi Eclipse GT:
                      "The Project That Never Ended, until it did"


                      next project? subaru brz
                      carpc undecided

                      Comment


                      • #12
                        Originally posted by soundman98 View Post
                        the main issue with doing it that way is the extra cost of cabling. it's really not the 'wrong' way, just not as cost effective as using a short length of wire to a solid chassis point.



                        while sean's setup will work fine with equally-gauged wires, it is also important to run at least 1 gauge larger(thicker wire) for the ground when using this method to try to reduce the resistance on the devices at the end of the wires.
                        Thanks for the clarification, that's what I thought but was not sure.

                        Thanks

                        Comment


                        • #13
                          Originally posted by soundman98 View Post
                          the main issue with doing it that way is the extra cost of cabling. it's really not the 'wrong' way, just not as cost effective as using a short length of wire to a solid chassis point.



                          while sean's setup will work fine with equally-gauged wires, it is also important to run at least 1 gauge larger(thicker wire) for the ground when using this method to try to reduce the resistance on the devices at the end of the wires.
                          Sorry don't take me the wrong way but this is not entirely true! The longer a ground is the more chance there is for noise to get introduced into a system. Also there are a lot of times where people get confused with what ground is a fault. Your signal cables if not of good grade(not twisted or shielded) can introduce noise as well.
                          Sean took what we call "The Boat" method. Even though in a boat you have to run a ground from the battery to wherever you are putting the equipment you have less chance of noise in a boat because you are surrounded by fiberglass. Fiberglass does not carry interference like a chassis of a car does. Not to mention the audio card or motherboard. Computers them selfs make noise which is filtered through the audio card.If that "filter" is no longer working correctly you will get noise. A four channel amp is the same way and is more sensitive to noise input through gain. Turning up the gain on an amp is not a volume control, it turns up the sensitivity on the input signal. I hope this has clarified things a little bit for you guys. If not ask away!

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                          • #14
                            as long as you explain yourself


                            but i still don't agree with it.. you are either using the car for a large ground conductor, with a short length of thinner wire connecting the component to that ground point, or a long wire-- either still is bathed in large amounts of EMI--either from nearby devices outside the car, or emi from devices mounted within the car. i see your point about a single small cable having a higher chance of EMI induction from internal EMI sources within the car, but i really don't think there would be much of a difference because the smaller cable also can be better isolated from those EMI sources, where using the car chassis as ground can't be moved-- the EMI source needs to be isolated.

                            at least that is how it works out in my head..
                            My OLD 2001 Mitsubishi Eclipse GT:
                            "The Project That Never Ended, until it did"


                            next project? subaru brz
                            carpc undecided

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                            • #15
                              the "noise" most people hear though those sources is most commonly a resistance to ground issue. A good resistance to ground to stay around and get no higher then .006 ohms. Depending on the wire used(oxygen free, copper plated, silver, short strand, long strand etc...) that plays a factor. So to eliminate or try to is to keep your grounds less then 18" long and ground in kick panel,rear strut towers,unibody, or to they frame it self. Then again it all depends on the car i.e. a corvette(fiberglass body and cast aluminum components).

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