what causes OLED interference at speakers

Rasseru · 13 Mar 2017 at 17:47

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

kitfit1 · 13 Mar 2017 at 19:13

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.

Rasseru · 14 Mar 2017 at 09:22

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

joeyjojo · 14 Mar 2017 at 09:26

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.

Rasseru · 14 Mar 2017 at 14:36

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

Steampunk · 14 Mar 2017 at 15:49

Rasseru said:
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

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

joeyjojo · 14 Mar 2017 at 15:53

What PSU?

Steampunk · 14 Mar 2017 at 16:06

joeyjojo said:
What PSU?

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

joeyjojo · 14 Mar 2017 at 16:22

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

Sorry, was aimed at the OP as in 'what PSU is in the PC?'

Rasseru · 14 Mar 2017 at 16:26

its coming out the speakers, they are active.

Dell precision T3500 with corsair hx 850 powering the GPU

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

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

Rasseru · 14 Mar 2017 at 16:29

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

joeyjojo · 14 Mar 2017 at 16:52

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

Steampunk · 14 Mar 2017 at 17:07

Rasseru said:
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

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.

Rasseru · 14 Mar 2017 at 17:31

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

neil_g · 14 Mar 2017 at 21:12

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.

Rasseru · 15 Mar 2017 at 01:45

Ground loop isolator being installed first. Hopefully that nails it

joeyjojo · 15 Mar 2017 at 08:41

Rasseru said:
They are JBL LSR305s, active internal power supplies

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.

Rasseru · 15 Mar 2017 at 11:06

joeyjojo said:
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.

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

Rasseru · 15 Mar 2017 at 11:41

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