New Headset using TRRS CTIA standard connector has low dB buzz

[antoniu200]

Hi! So, I recently had my Plantronics headset die (one 3 pole connector for the mic, another one for the headphones), because of the bad quality potentiometer, so I bought myself a new headset: a JBL Tune 500 (one 4 pole connector for both the mic and headphones). All great and dandy, until I notice a subtle buzz sound (very, very low dB) coming out of them when I connected them to my PC, but the sound wasn't present on my Xperia phone. Now, the first thing I tried was replacing my front 3.5mm jacks. After replacing them, the sound was still there.

Did some digging, and found out it could be a ground issue. I saw some people suggesting an adapter from one 4 pole connector to two 3 pole connectors. Had one ordered, arrived yesterday and the buzz sound is still there.

Now, I gave this a tought and I came to the conclusion that the adapter might not be using the ground connection.

And the question comes: what do you all think could be the problem here? My other Plantronics headset didn't have this buzz sound, and neither does my friend's headset when connected to my computer (also two 3 pole connectors). However, any 4 pole headset I connect to my PC has this buzz sound occur, as soon as I run some more intensive programs.

 

[sgrossklass]

The 4-pole headset connects headphone ground and mic ground together. This results in a ground loop partially inside the PC. In a nutshell, you're screwed.

If all you need the headset for is telephony / voice chat and the like, I would probably go back to something more traditional with two separate plugs. Maybe even some traditional headphones of higher sonic aspirations plus a Modmic if you feel fancy... the choice among actually good-sounding headsets has never been all that great. Even a rather good-sounding mic setup is no longer necessarily breaking the bank, though you'd probably still be looking at the better part of 100 € at least.

 

[antoniu200]

Well, then, wouldn't desoldering either the mic ground or the speaker ground from the PCB help?

 

[sgrossklass]

Well, then, wouldn't desoldering either the mic ground or the speaker ground from the PCB help?

Potentially yes, but you might have enough common ground return resistance that whatever plays in your headphones is heard loud and clear in the mic. People have had that happening, so don't be too surprised if it does occur.

You'd essentially be changing the grounding scheme in this area from star to bus.

 

[antoniu200]

Potentially yes, but you might have enough common ground return resistance that whatever plays in your headphones is heard loud and clear in the mic. People have had that happening, so don't be too surprised if it does occur.

You'd essentially be changing the grounding scheme in this area from star to bus.

I've asked this question on another forum and I've just received an answer. And it's interference related. Basically, the Graphics Card consumes so much it causes interference with the dedicated Sound Card sitting above it. And this does indeed seem to be the cause, as on my other PC the sound does still occur, but it's far from audible. You have to know exactly what to try and hear and you will still have a hard time hearing it.

If you still think it's a ground issue, please say so, I just want this issue solved.

 

[sgrossklass]

Graphis cards have a habit of drawing a lot of current, and you don't want to be sharing a ground path with them. They also have a lot of current going around internally though, invariably in loops of finite size, which can couple to other ground loops inductively - and there is basically no difference between a ground loop and a loop antenna. The inside of a PC is about the last place where you want to have ground loop issues. Due to the low levels involved, the mic input is also (literally) the most sensitive to any such issues.

At least your front panel has some sensible ground routing to begin with - there must be a lot out there where USB and audio grounds are just tied together and connected to chassis. I suppose it's a cheap way of getting your EMI compliance, but in terms of audio it's rather catastrophic.