Poor quality audio from PC. What gives?

[Manmademan]

I bought the termination cap as cybepine suggested and capped an unused Radio coax socket in the wall. (Pictures attached below)

So there's been a development:
The extension cord improvement's effects are almost completely negated when I close the window in my kitchen.
I came to this realization when I noticed that the audio sounded oddly poor even after all the "improvements" I had in place. Turns out, I had closed the kitchen's window the day before. The window has been constantly open for the past 6+ months and I closed it yesterday for the first time since because it's getting chilly. I opened the window again and the clarity is back to before, just like that. It is that bad.
Do I start wearing a jacket inside and have increased audio clarity, or do I close the window and lose audio clarity? This is laughable.
When there is an unobstructed line of sight outside, the opened window must act a quick way out for the interference. Even glass panes seem to trap it inside. This is just what makes the most realistic sense in my head.
I don't know if there is a connection here, but there is another set of 2 water pipes and grounded radiator in the kitchen too, identical to the ones in the living room, just shorter. The openable kitchen window is 10cm above the radiator.


The termination cap helps with the audio clarity and the interference is definitely reduced, but doesn't completely get rid of it.
I still notice the increase and decrease in audio clarity/focus when I plug my headphones into my phone, listen to music and walk back and forth in my apartment. The audio doesn't sound as muddy anymore even when I stand in the TV coax outlet and radiator corner in my living room where it has always sounded the worst. It almost starts to feel like the effect of the interference is halved.

Okay. So I had the foresight to buy 2 termination caps, so I capped both the TV and Radio sockets, and the interference seemed to stop altogether when I had my headphones plugged to the phone. It was very hard to notice any changes in audio clarity, either in the worst spot in the living room or at the apartment's front door where the audio has sounded the clearest.
When I capped the Radio socket, it took the same 15-20 minutes for the clarity to be as strong as possible/settle, just like with the extension cords. There's almost a ripple; the audio clarity goes worse, good, bad, then suddenly very good, then worse, then balanced where it settles. It's all subtle and very gradual.
Once I took the TV socket's cap off and plugged the coax splitter back into it, the interference came back, but to the level as it was after I had capped the Radio socket.
The TV socket is radiating something even with the high quality coax splitter plugged into it.
With that, I'll order the MoCA filter next and hope that it will be the ultimate fix to this. Otherwise, I'll fucking explode.

[cybepine]

Since this apartment building was built in the early 70s, the only coax sockets in the entire apartment are the TV and Radio sockets in the living room. I also use an Axing TZU 21-65 TV/Data coax splitter which both my TV and internet router coax cables are plugged into. In this case, where should the filter be placed? Straight into the wall? To the TV/Data coax splitter's "Data" leg?

I also read that since the actual TV/Radio coax wires coming to this apartment inside the walls are "chained/chain installed", because the building is old, the coax cables continue from another person's apartment in this building to my apartment, and continue further to somebody else's after mine, installing a MoCA filter might cause signal or interference issues further down the wires, in the next person's apartment.

You are quite right. The coax is connected to all apartments and it could cause signal issues. I would first call your cable company to ask how to proceed and how it is done in you apartment complex. Also ask if there is any filter installed. And even ask to come check your apartment, because you have this serious interference.

Like I said I am not sure it will work. I would place it at the first point of entry that is usually outside house. But in your case (if it works?) straight to the wall.

Is this something to consider? Then again, to put this in videogame terms, all this is level 100 information to me and I'm level 1.
The only MoCA filter I found is on Amazon, is this correct?

Yes, that is one of models.

[Manmademan]

So.. maybe this will be the last update because the more things I try out, the more impossible it starts to feel to get to the issue's root or find out where the interference really originates from. I don't know who to call: an ISP tech, electrician, or an exorcist, because this place starts to feel interferencially haunted beyond belief.

The MoCA filter wasn't the ultimate fix as I had hoped. Instead it helped confirm that whatever I plug in to the coax sockets always alters the frequency or intensity of the interference in different ways, depending on what was plugged in.
For example, when I plug in coax signal splitters with varying passband frequencies: 0-1000Mhz, 5-1000Mhz, 5-1218Mhz, 5-900Mhz,
0,1-870Mhz, LTE filter 0-794Mhz, MoCA filter 5-1002 MHz passband and 1125-1675Mhz stopband.
From this testing, I noticed that the lower the passband's max. frequency, the smaller it made the audio sound. This wasn't good and didn't help. The higher the frequency, the better? No. It didn't fix the issue but only altered something in the audio.

After testing the above, I also tested a terminator with the capability to block DC, then two sheath current filters which I plugged into both coax sockets, then -10dB attenuators to reduce the incoming power from the sockets. All these things, just like the splitters above, always altered the interference's "frequency" or intensity. From this I can conclude that the coax sockets are probably not the cause, but most likely the sockets also receive the same interference and the filters only help filter out certain parts of it.
Judging by how much the sockets can influence the audio, they definitely seem to be connected to the electrical system. Maybe this is basic information.

After testing everything I could think of related to coax sockets, I found that these completely random things alter or even help the audio clarity and image quality more or less (the interference affects AV quality equally):

1. Pulling any curtains or blinds away so there is as little in the way of the apartment's windows, probably where the interference wants to go. Now I always pull all curtains to the side because it really does help.
2. Leaving all apartment doors fully open. Now all my doors are always open, it helps just like with the above.
3. Making sure none of the wall outlets are blocked by anything. I recently relocated my microwave in the kitchen so it wasn't blocking the grounded outlet behind it.. and surprisingly that made a noticeable difference to the audio. There's that. HOW?
4. Turning the thermostat dial in my fridge to the lowest value helps, highest makes the audio worse. The fridge seems to do something here.
5. Setting all the apartment's radiators' thermostats to the lowest/max alters the audio. Lowest dial setting = the audio sounds drier, max = the audio sounds warmer, but these do not fix the clarity, or really help. This also takes hours to "settle".
6. Putting away my big circular metal analog clock on the wall. The metal part is disturbing the interference in some way. That's funny.
7. Moving my WLAN/WiFi router around or placing my phone with WiFi enabled near my PC subtly alters or disturbs the interference.

From all this I can only take away one thing: anything that is part of the electrical system in this apartment, radiates interference that it is truly pervasive, and anything and everything I do (which isn't related to plugging things in or out) can "disturb" it temporarily, until it gradually settles/balances out/equalizes over a certain time period, and it only ever manifests as reduced audio/image quality and clarity. What even on earth. I have zero clue where I currently stand on the way to fully fixed, between 0-100%.

I have attached below two images of before and after plugging something into the coax sockets (I forget), but these should paint a clear picture of how much the interference is influencing the clarity of the image. It's equally as noticeable when it comes to audio.
Notice how there is a stronger diagonal pattern all over the first image. It's only visible to the camera in my phone, but this is what the interference could look like.

[themagic]

So.. maybe this will be the last update because the more things I try out, the more impossible it starts to feel to get to the issue's root or find out where the interference really originates from. I don't know who to call: an ISP tech, electrician, or an exorcist, because this place starts to feel interferencially haunted beyond belief.

The MoCA filter wasn't the ultimate fix as I had hoped. Instead it helped confirm that whatever I plug in to the coax sockets always alters the frequency or intensity of the interference in different ways, depending on what was plugged in.
For example, when I plug in coax signal splitters with varying passband frequencies: 0-1000Mhz, 5-1000Mhz, 5-1218Mhz, 5-900Mhz,
0,1-870Mhz, LTE filter 0-794Mhz, MoCA filter 5-1002 MHz passband and 1125-1675Mhz stopband.
From this testing, I noticed that the lower the passband's max. frequency, the smaller it made the audio sound. This wasn't good and didn't help. The higher the frequency, the better? No. It didn't fix the issue but only altered something in the audio.

After testing the above, I also tested a terminator with the capability to block DC, then two sheath current filters which I plugged into both coax sockets, then -10dB attenuators to reduce the incoming power from the sockets. All these things, just like the splitters above, always altered the interference's "frequency" or intensity. From this I can conclude that the coax sockets are probably not the cause, but most likely the sockets also receive the same interference and the filters only help filter out certain parts of it.
Judging by how much the sockets can influence the audio, they definitely seem to be connected to the electrical system. Maybe this is basic information.

After testing everything I could think of related to coax sockets, I found that these completely random things alter or even help the audio clarity and image quality more or less (the interference affects AV quality equally):

1. Pulling any curtains or blinds away so there is as little in the way of the apartment's windows, probably where the interference wants to go. Now I always pull all curtains to the side because it really does help.
2. Leaving all apartment doors fully open. Now all my doors are always open, it helps just like with the above.
3. Making sure none of the wall outlets are blocked by anything. I recently relocated my microwave in the kitchen so it wasn't blocking the grounded outlet behind it.. and surprisingly that made a noticeable difference to the audio. There's that. HOW?
4. Turning the thermostat dial in my fridge to the lowest value helps, highest makes the audio worse. The fridge seems to do something here.
5. Setting all the apartment's radiators' thermostats to the lowest/max alters the audio. Lowest dial setting = the audio sounds drier, max = the audio sounds warmer, but these do not fix the clarity, or really help. This also takes hours to "settle".
6. Putting away my big circular metal analog clock on the wall. The metal part is disturbing the interference in some way. That's funny.
7. Moving my WLAN/WiFi router around or placing my phone with WiFi enabled near my PC subtly alters or disturbs the interference.

From all this I can only take away one thing: anything that is part of the electrical system in this apartment, radiates interference that it is truly pervasive, and anything and everything I do (which isn't related to plugging things in or out) can "disturb" it temporarily, until it gradually settles/balances out/equalizes over a certain time period, and it only ever manifests as reduced audio/image quality and clarity. What even on earth. I have zero clue where I currently stand on the way to fully fixed, between 0-100%.

I have attached below two images of before and after plugging something into the coax sockets (I forget), but these should paint a clear picture of how much the interference is influencing the clarity of the image. It's equally as noticeable when it comes to audio.
Notice how there is a stronger diagonal pattern all over the first image. It's only visible to the camera in my phone, but this is what the interference could look like.

I have no fucking what the issue is for you but by just read the first lines...i have here better experience sometimes with WIFI than through LAN connections....and that all completely fucked my mind. I know that here some Guys who had the same exact weird improvement experience through Wifi ...but not for very long play time...

but that all another Topic and its all about Wifi and how it can affect you rOnline Gameplay....just by switching frequency or channels levels....

and even the audio changes...that true stuff.