Game Input MultipleXer

So here's the thing: I built my own GIMX adapter using teensy 2.0 and UART converter that I ordered from China. I use a G27 firmware for G920 wheel on PS3 and it works flawlessly. Everything is mapped correctly, wheel range is correct, the full shebang.
Due to the fact that I don't have a dedicated cockpit yet I use my computer desk for playing and since I have only one main pair of headphones for now it was very tiring to switch from one headphone jack to the other(I use an HDMI audio extractor to have a headphone option for my PS3) I decided to get my PS3 to be heard through my PC speakers to be able to chat with friends, listen to podcasts/music and play on my PS3 at the same time. So I use M/M 3.5mm cable that goes from HDMI audio extractor into a line-in on my motherboard's audio card, it then goes through Voicemeter software and into my headphones connected to my Behringer UM2. That was the explanation of the whole commutation.

Now for the problem: whenever I listen to line-in channel with GIMX adapter connected to the PS3, I hear electronic hum through it with some oscillations that appear to be USB signals being sent through the bus. I am almost 100% sure that GIMX adapter is causing this as when it's unplugged from the PS3, I only hear a faint normal combination of white noise and EM-interference if I amplify the sound enoough. I will try and record this sound for you to understand what I'm talking about. I didn't try this on my PS4 as I lended it to my friends for a couple of weeks (guys want to play Ghost of Tsushima and The Last of Us ) but I feel like it's something to do with the HDMI audio. The only idea I had so far is to buy an AV cable for my PS3 and run the audio separately through it but I'm not sure if it will help. Thing is, it will not work for my PS4, I'll have to find another solution if this problem persists on that console. Maybe it's something in the adapter? It's in a pretty tight enclosure and maybe there's something that causes this buzz? If anyone ever encountered something like this and fixed it, please let me know.

Here's a link to the sound file with the noise: https://sndup.net/8szz

Solution: don't use crappy aux cables, spend $10-12 and buy a good thick cable with quality connectors, preferrably soldered by you or in-shop and not pre-made from a factory.

One thing i would look at is if the HDMI cables is goldplated. I have had numerous audio interference with cables that are not goldplated (ex. rca - 3.5 cables while connected to ps3) test another HDMI cable between the HDMI audio extractor and PS3 and see if the problem persist.
Second thing is the motherboards soundchip. Check and see if there are others that has same issues with the same motherboard. Some motherboards use cheap components or have to many circuits around the sound chip creating Buzzing interference. (This could explain when the gimx is connected).
If that doed not help i would strongly test same setup on another computer and before buying a cheap PCI-E soundcard.

ckaiycool wrote: ↑Tue Aug 10, 2021 6:43 pm One thing i would look at is if the HDMI cables is goldplated. I have had numerous audio interference with cables that are not goldplated (ex. rca - 3.5 cables while connected to ps3) test another HDMI cable between the HDMI audio extractor and PS3 and see if the problem persist.
Second thing is the motherboards soundchip. Check and see if there are others that has same issues with the same motherboard. Some motherboards use cheap components or have to many circuits around the sound chip creating Buzzing interference. (This could explain when the gimx is connected).
If that doed not help i would strongly test same setup on another computer and before buying a cheap PCI-E soundcard.

So I tested around some more: I connected 3.5 mm cable from HDMI extractor to my audio interface's instrument input(it's mono but I'm just testing the noise) and the noise was still there. Granted the interface is still connected to my PC through USB and audio is still processed partially on my PC so yeah, still the same enclosed system. As for HDMI, the cable that was in my PS3 was gold-plated. It's a bit worn out on one end though so I switched the cables around just for good measure and the result is the same. Same high-pitched whine with buzz.
Funny observation I made: I connected a M/F cable to the audio extractor and then connected the headphones to it so it was going straight between PS3 and my headphones without my PC interfering with any of it and I didn't hear a thing! Well, some EMI but that's to be expected, nothing unusual or anything of this whine sort I mean.

Now I see two possibilities: either it's a shoddy audio cable (I didn't buy it for this specific use-case, it's a really old flimsy cable that was lying around in my closet for god knows how long, I just thought a few damned strips of copper in a rubber enclosure can't be THAT bad) that can't deal with all the EMI going on or it's my motherboard creating too much EMI in the first place. I checked if other people had this noise issue on their microphone-in ports and there are several topics on different forums saying that circuitry on the mobo is quite bad and that the static is very noticeable.

I'll probably go and buy a new M/M 3.5mm cable first and see how it goes. I wouldn't want to spend more money on a PCI-E sound card as I already have a usb audio interface and just for a stereo line-in it's not worth it IMO.

Thanks for your input btw, I really appreciate it!

Crewarookie wrote: ↑Tue Aug 10, 2021 7:48 pm Thanks for your input btw, I really appreciate it!

Glad i could help

So 10$ and one new thick balanced cable later there's ZERO whine and just a tad bit of white noise at MAXIMUM sound level for the device. Lesson: check your cables and don't use cheap stuff!

Well done