noise from line out to my amply ,why?

Discussion in 'hardware' started by mantra, Dec 28, 2017.

  1. mantra

    mantra Registered Member

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    hi

    i have a normal cable very cheap , and i have connected my line out of my desktop and laptop and imac
    i can notice a noise during the boot but as soon as windows load the drivers the noise does disapear
    the same i did with my imac , turn on my amply and turn on my imac , i can hear noise from the speakers ,during the boot the noise disapears , macos doesn't use drivers i guess kexts
    the point if i shut down my imac , my laptop or desktop ,(they are connected to an ups)
    i changed cable i bought a ugreen , and there is no more noise
    may i know what does cause noise with a normal cable?
    and why does a cable like ugreen suppress noise ? and suppress noise or audio frequency ?

    thanks
     
  2. Bill_Bright

    Bill_Bright Registered Member

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    Impossible to tell from here but most likely it is a grounding or shielding problem with the cheap cable. That is, it does not provide a good ground between components, or it has poor shielding and is failing to suppress spurious interference - or both.
     
  3. mantra

    mantra Registered Member

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    hi
    but mostly motherboard like asus use the same audio chip realtek , do they make noise when they are connected to an amply with an old cheap audio cable?
    and the cable like Ugreen 10591 suppress nosie , they claims to suppress noise because there is no oxygen in the copper
    thanks
     
  4. Bill_Bright

    Bill_Bright Registered Member

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    That's just marketing nonsense.

    And even the best cables can be damaged or improperly made at the factory.
     
  5. Peter2150

    Peter2150 Global Moderator

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    All right ENOUGH!!
     
  6. mantra

    mantra Registered Member

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    hi Bill
    thanks for

    hi Peter
    what's up?
    just because sometime i have problem to understand english ,and use google translator,can't ask information in this forum?
    "all right enough" google translator translate "ok and stop it"
    thanks
     
  7. Peter2150

    Peter2150 Global Moderator

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    Hi Mantra

    That Enough was not meant for you, but for two others
     
  8. trott3r

    trott3r Registered Member

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    I used to listen to my commodore amiga 4000 cpu working hard by turning up the line level out on my amplifier :)
    It was up to 5/10 though when i normally used 2/10.
     
  9. Bill_Bright

    Bill_Bright Registered Member

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    Well, high-speed digital switching devices have a tendency of producing EMI/RFI. This is exactly why products in the US must comply with FCC (Federal Communications Commission) guidelines for RF shielding and emissions. The UK, EU and other jurisdictions have similar regulations.

    Back in prehistoric times with your Commodore (I still have my C64 stuffed in closet! :)) the regs were not as stringent and EMI/RFI shielding and suppression was not as sophisticated either.

    Either that, or you had flaky grounding. ;)
     
  10. trott3r

    trott3r Registered Member

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    Spread spectrum in the bios is supposed to help with rfi I believe but i seem to remember that it had some negative affect.
    Maybe on speed of the cpu.
     
  11. Bill_Bright

    Bill_Bright Registered Member

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    It's been so long since I've seen that feature, I had to look it up to refresh my memory.

    That was a motherboard FSB setting on older motherboards used to reduce EMI (similar to RFI, but "electromagnetic" rather than "radio frequency") on the memory bus by slightly varying the FSB speed. Most of the time, it did have a negative affect (especially when overclocking) and fortunately, was disabled by default.

    Looking at my motherboard manuals, none of my current systems have that setting in the BIOS anymore. I am assuming due to modern CPUs using different methods to communicate.

    Since replacing the cable fixed the OP's problem, I suspect that was not the problem here.
     
  12. mantra

    mantra Registered Member

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    Hi Bill
    i have noticed the same with an imac ,line out with a very cheap cable it's noisy, by the way the cable is 10 meters
    thanks
    happy new year
     
  13. Bill_Bright

    Bill_Bright Registered Member

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    That's very long - especially for low-level audio signals.

    The greater the distance, the greater the resistance. The greater the resistance the greater the signal loss. The greater the signal loss, the lower the signal to noise ratio. And that is not good.

    And there's no way to eliminate that. To minimize the adverse affects of long cable runs, use better cable. This means go with a smaller gauge cable (smaller gauge = larger conductor/wires for lower resistance) with quality terminations (connectors - including the crimp and soldering job), and depending on cable type, better grounding and shielding.
     
  14. mantra

    mantra Registered Member

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    Hi
    great point about the long cable , i did know about it , i mean i was sure that short cable or long cable don't make differents
    5meter or 3meter are still too much ?
    thanks
     
  15. Bill_Bright

    Bill_Bright Registered Member

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    There are too many variables to say. It depends on the cable quality, wire sizes (gauge), and initial signal strength. 6 - 10 feet (~3m or less) is probably not a problem (assuming the cable is in good condition). More than that and I would worry about signal loss, noise (at least with analog signals) and interference.

    Frankly, this is why I generally make my own cables. Then if I need an 18 inch cable, I don't have to buy a 6 foot cable.
     
  16. mantra

    mantra Registered Member

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    hi
    last question , is there a non exansive cable with these features of 5 meter, i know it's too long ,but if i ask the component to make my own cable it costs really a lot
    thanks and happy new year Bill
     
  17. Bill_Bright

    Bill_Bright Registered Member

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