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  • problems with aux sound

    Hello guys, so i have this for you and i really hope you can help me cause otherwise my installation would be pretty useless
    So, i completed my installation of my pentium 4 pc and i have this problem.
    I am trying to listen from my radio-cd the pc's sound via an aux connection
    -the same radio works with aux with my netbook
    -the same pc works with normal pc speakers...
    -Also the sound car is reaaaaally old (pantium 4 age, on board...)
    So i have connected them with a 5m aux extantion, and then a 1m male-male aux calbe... the same cable except that its long, it also passes near the power supply cables of the inverter and the pc powe supply (near 750w total) and its not anything spacial to be shielded or something.... anyone has something to propuse? any help would be very aprixiated

  • #2
    Separate it from the power cables. (If interference is your problem.)

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    • #3
      thanks for the details, but what is the problem your having?
      My OLD 2001 Mitsubishi Eclipse GT:
      "The Project That Never Ended, until it did"


      next project? subaru brz
      carpc undecided

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      • #4
        lol yea i forgat:P i cant get the damned car sound system, to play music from the pc..... also i now think that when i connect the sound cable, the mic dosent work so well...

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        • #5
          have you checked that your plugging into the correct port? if you can change the assignments of each port, have you checked that the one your plugged into is correct? and have you tried speakers on the extension cable to make sure that works?
          My OLD 2001 Mitsubishi Eclipse GT:
          "The Project That Never Ended, until it did"


          next project? subaru brz
          carpc undecided

          Comment


          • #6
            they are in correct ports since the mic is working. but i indeed havent tried the cable with other speakrers (i have two cables, one long and one small connected, and i have tried th small (it worked))
            BUT i have used enother speaker with its own cable directly into the pc and it didint worked.... i'm leaning towards interfiaring with the amplifiers cables...(will try to see if that will solve it today)

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            • #7
              okey so. i bought a new sound card and works. But still i get the buzzing sound as background noise..
              i have connected the inverter to the battery, and whn i start the engine the noise gets worse...
              i have tried many diferent groundings (as well as battery itself) and the noise stays exactly the same.... any ideas?

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              • #8
                well, inverters can be problematic because of the A/C signal, but it could also be a ground loop (you'll need to search, my keyboard hates me for retyping the troubleshooting steps)...
                My OLD 2001 Mitsubishi Eclipse GT:
                "The Project That Never Ended, until it did"


                next project? subaru brz
                carpc undecided

                Comment


                • #9
                  no its not a ground loop.. i checked many diferent groundings(including battery)... i also have tried enother battery so its not a batter prob either.. so.. inverter, or pc itself??.. can u tell me if its possible for either?
                  i am also thinking, for beating the sound, to put a hpf on the sound system. but then i will win it only in sound... does it go to the usb and screen as well??? cause my touch dosent work either...

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                  • #10
                    I FIXED IT!! IS there a way , i can say in the post that its fixed, so it could help others too?
                    anyway... what was faulty was the Power supply of the pc.. i dont know why. But i cut open the cable that goes from the iverter to the power supply, and combined the ground one (the internal grounding cable)(going from the power supply back to the inverter) with a grounding in my car, instead of back. That took care of all the buzzing noises!!!
                    \

                    Comment


                    • #11
                      That's what we call a ground loop. Or it may be - your description is a bit ambiguous, else I amn't awake.

                      Funny - I was going to reply "So what ground did you cut?" to your previous
                      Originally posted by settra View Post
                      no its not a ground loop...
                      The question I have is whether fuses/protection will work if you have a ground fault on your PC PSU, though I think it will.


                      For those interested in inverter "earthing" (and dc-dc earthing since a dc-dc converter is also dc-ac but with its output converted back to dc), keep reading.
                      Otherwise don't.


                      Normally ground loops are fixed by breaking the signal ground - ie, breaking the (pair of) shields in an audio signal path.

                      But it may be that what you have done is bond a noisy floating chassis to the vehicle ground. That's normally done by the signal cables to the PC (chassis being signal return/shield) or by adding bypass capacitor(s) from PSU chassis to vehicle ground.


                      FYI - normally inverter AC outputs are totally isolated - ie, floating with respect to input DC +12V and ground.
                      The inverter output AC "earth" (ground) should be connected to its L2 output. [ IE - to imitate domestic AC distribution with 3 pins (active aka hot or L1, neutral aka return or L2, earth or ground) where the neutral and earth are bonded together at the power-source end, the inverter output's L2 is joined to its output earth/ground. ]
                      That can mean to totally floating AC system between the inverter and PC PSU.
                      Or it could be vehicle-chassis connected if the PC has its PSU's chassis(/earth) joined to the motherboard ground (via audio or other connections to vehicle ground), or otherwise if the inverter's output AC earth is connected to the inverter chassis which then touches the vehicle ground.
                      Easy eh?

                      Unfortunately it isn't always simple or obvious. The only "definite" should be that inverter AC outputs L1 & L2 aka active & neutral are totally floating (isolated) from the DC input EXCEPT when deliberately wired otherwise - eg, by the user. (Or maybe authorities requiring output earth to inverter chassis, and then maybe output earth(/chassis) to output L2/neutral.)
                      Hence the output AC might be floating which may be good from a safety point of view, but it means a floating AC chassis or antenna that might need bonding to ground.
                      Ah, the fun and games.

                      Otherwise an inverter is essentially the same as a dc-dc converter - they both convert to dc.
                      But the dc-dc converter may have its fully internal ac shielded by its chassis which is itself connected to vehicle chassis on typical automotive dc-dc converters (by both input & output for negative ground vehicles; noting that on typical dc-dc converters, the outputs are NOT isolated from the input unless they use a separated 2-winding transformer instead of an inductor or auto-transformer; most simply use inductors).


                      I'm going back to bed.

                      Comment


                      • #12
                        Originally posted by OldSpark View Post
                        Otherwise an inverter is essentially the same as a dc-dc converter - they both convert to dc.
                        But the dc-dc converter may have its fully internal ac shielded by its chassis which is itself connected to vehicle chassis on typical automotive dc-dc converters (by both input & output for negative ground vehicles; noting that on typical dc-dc converters, the outputs are NOT isolated from the input unless they use a separated 2-winding transformer instead of an inductor or auto-transformer; most simply use inductors).


                        I'm going back to bed.
                        hope you slept good (time to wake up!)


                        while the principles of invertors, and dc-dc's are the same, the applications, and switching frequencies are different(as you know).. dc-dc's use a very high, switching freq. while most inverters are limited to a very-audible 60hz...

                        i had a similar problem using a car subwoofer in the house using a pc psu. i had to ground the outside of the rca cable to the ground of the ac power supply to get rid of the hum that it had..
                        My OLD 2001 Mitsubishi Eclipse GT:
                        "The Project That Never Ended, until it did"


                        next project? subaru brz
                        carpc undecided

                        Comment


                        • #13
                          Oldspark dude.. Sry but i didint understood a s@#t from what you just discriped i dont even know what the dc-dc /ac-dc diferences have to do with that post:>

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                          • #14
                            Originally posted by soundman98 View Post
                            ... dc-dc's use a very high switching freq. while most inverters are limited to a very-audible 60hz...
                            Not quite...
                            Inverter output is mains frequency (50 or 60Hz), but internally they are high frequency.
                            For example, the 1200VA inverter I once spec'd used 50kHz switching.

                            Whereas dc-dc is say 12Vdc - ac - 20Vdc, inverters are 12Vdc - ac - 150Vdc which is then "stepped" out as maybe 80V, 120V,80V,0V,-80V etc for 120VAC.

                            A true-sine inverter would convert to above 120VAC x root-2 (the peak voltage) = 170V (say 180Vdc) and then high-frequency modulate (PWM) to get the sinewave.
                            (Not that I described the -ve half of the cycle.)

                            So both use high frequency conversion.

                            Even if inverters only had their mains output (50/60Hz), if stepped wave, it would have "infinite" harmonics - ie, frequencies of 3x, 5x, ... 157x, 159x ... the "fundamental" frequency (eg, 60Hz). [ Or is it 2x, 4x, etc - a square wave is a summation of all (even or odd) harmonics to infinity....

                            Fun stuff eh?

                            Hence why I say inverters = dc-dc converters.

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                            • #15
                              ye ye, but all that stuff are still irelevant to the post. if you can explain why the problem was solved the way i told in the first page, then plz do it, else, dont comfuse people up..

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