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what causes OLED interference at speakers

Discussion in 'Home Cinema & Hi-Fi' started by Rasseru, 13 Mar 2017.

  1. Rasseru

    Hitman

    Joined: 17 Jan 2017

    Posts: 582

    Changed to usb soundcard which used to eliminate ground loop on my laptop, and its still here.

    Is it even a ground loop problem, or specific to OLED? its my first of these tvs. I've tried to google and it not many pc users with this problem it seems
     
  2. kitfit1

    Mobster

    Joined: 24 Feb 2003

    Posts: 3,947

    Location: Stourport-On-Severn

    To be honest, i have no idea what your actual problem is. You are going to have to be a lot more more detailed and specific, as in what kit you have, how you are using it and exactly what the problem is.
     
  3. Rasseru

    Hitman

    Joined: 17 Jan 2017

    Posts: 582

    Sorry, i heard someone mention these TVs buzzing. I thought it might be a known thing with PC users.

    LG OLED C6, JBL LSR305 actives and theres a buzz from the speakers, it is directly related to the screen. So when I rotate in a game, or transition from dark to light areas the sound changes in pitch.

    I have tried onboard sound & a basic usb soundcard. The cabling is pretty good, its minijacks to 1/4" jacks, but soldered well. I can change to XLR but the source jack into the onboard/soundcard is always going to be minijack. I dont know if that stops the XLR from being grounded or not
     
  4. joeyjojo

    Soldato

    Joined: 2 Dec 2005

    Posts: 5,515

    Location: Herts

    So you have a PC plugged into an LG TV, and some speaker/hifi separates of some sort?

    Seems unlikely to be interference getting from the TV back to the PC and then to the audio interface, then speakers. You could make fairly certain of this by using an insulated interconnect like S/PDIF TOSLINK. The only point of contact then is in the mains wiring. Seems a long shot though and more expense.
     
  5. Rasseru

    Hitman

    Joined: 17 Jan 2017

    Posts: 582

    Its not the TV turns out. Something else is causing sound interference. firestrike 3dmark stress test is really loud, and doesnt matter if onboard or usb, maybe its power related ground loop from the 6-gangs or something, when the pc is drawing a lot of juice the sound changes
     
  6. Steampunk

    Sgarrista

    Joined: 1 Jun 2013

    Posts: 8,848

    This sounds like coil whine. Sure it's not coming from a graphics card, PSU, or some other undamped coil component?
     
  7. joeyjojo

    Soldato

    Joined: 2 Dec 2005

    Posts: 5,515

    Location: Herts

    What PSU?
     
  8. Steampunk

    Sgarrista

    Joined: 1 Jun 2013

    Posts: 8,848

    In the laptop or TV. Or any other powered thing that's hooked up and has coils in it.
     
  9. joeyjojo

    Soldato

    Joined: 2 Dec 2005

    Posts: 5,515

    Location: Herts

    Sorry, was aimed at the OP as in 'what PSU is in the PC?' ;)
     
  10. Rasseru

    Hitman

    Joined: 17 Jan 2017

    Posts: 582

    its coming out the speakers, they are active.

    Dell precision T3500 with corsair hx 850 powering the GPU

    Oh, just checked out a video on that, yeah, its loud coil whine coming out the speakers. Like coil whine amplified or coil whine 2, the return.


    Its not so high-pitched though due to the speakers, so its more like coil rasp lol
     
  11. Rasseru

    Hitman

    Joined: 17 Jan 2017

    Posts: 582

    ah, but it isnt present with the speakers off. But it has the same thing where when you move about in games the pitch changes

    edit* I only noticed it since OLED & GPU upgrade, so maybe its the both of them drawing power and oscillating GPU, with the speakers all on the same circuit
     
  12. joeyjojo

    Soldato

    Joined: 2 Dec 2005

    Posts: 5,515

    Location: Herts

    What are the speakers, and how are they powered? (E.g. power brick at the wall, internal power supply...)
     
  13. Steampunk

    Sgarrista

    Joined: 1 Jun 2013

    Posts: 8,848

    If you have a long extension lead, try powering the speakers off a different power circuit, like upstairs or the kitchen if it's on a separate ring. It might confirm interference, ground loop, etc, then maybe it can be filtered. Actually, then try powering the PC and the TV off the different circuit and see what happens.
     
  14. Rasseru

    Hitman

    Joined: 17 Jan 2017

    Posts: 582

    Yeah i'm gonna try that all out. Need to get some more extension leads from my bedroom.

    They are JBL LSR305s, active internal power supplies
     
  15. neil_g

    Capodecina

    Joined: 9 Dec 2007

    Posts: 10,343

    Location: Hants

    I had issues with interference coming from my pc to active speakers. Tried motherboard and pci sound card.

    Only thing that fixed it was going optical to a SMSL SD793-II dac then rca from the un-amped output to active speakers. Gained a good headphone amp by doing that too.
     
  16. Rasseru

    Hitman

    Joined: 17 Jan 2017

    Posts: 582

    Ground loop isolator being installed first. Hopefully that nails it
     
  17. joeyjojo

    Soldato

    Joined: 2 Dec 2005

    Posts: 5,515

    Location: Herts

    Strange, they should have pretty good (in noise rejection) power supplies.

    The thing about ground loops is they sound like mains frequency, whereas yours is higher pitched.
     
  18. Rasseru

    Hitman

    Joined: 17 Jan 2017

    Posts: 582

    Yeah this isnt 50hz hum, I know that frequency quite well. It is definitely when the 1080 is pushing pixels. I've tried different PSUs & sound cards.


    It also might still be my OLED, because the brightness can control the pitch change? i'l record it sometime
     
  19. Rasseru

    Hitman

    Joined: 17 Jan 2017

    Posts: 582



    the whine in all its glory. sorry for the bent neck but I cba to edit it



    I dont know why the video kept cutting out volume (it was hella loud & constant in the room, maybe my fingers on the mic), but this is it synced to the FPS when I just rediculously maxed it out at 4k with tons of AA
     
    Last edited: 15 Mar 2017