DIY Ground Loop Isolator 1:1, help

Thinking of building my own HiFi RCA stereo ground loop isolator with 1:1 ratio for transformers.

Trying to mimic Supra AGS-10k
Frequence intervall: 15 Hz - 22 kHz
In- and Out Impedance: 10 kOhm
Ratio: 1:1

Any suggesstions for this DIY project?

That Supra AGS-10k costs around 60 euro so if i can build a similiar cheaper im happy. If not im buying it.

Use for reciever sub preamp and subwoofer amp.
Having issues with noises from PC via HDMI and antenna cable tv to antenna socket/wall. Humming in subwoofer.
 
Thank you for all the suggestions.
I know that there allready are built working products.
But what is the fun with that to not DIY?

That Monacor looks premium and seems to have "premium" specs on the paper too.
It differce a little in the frequency range but.. i dont know.

My main usage of this ground loop isolator is to eliminate my audible noise when using my computer. HDMI and RCA seems to pick it up.

Signal path: Onkyo TX-NR818->Subwoofer PREOUT RCA (mono)->RCA single end with Y-split->Ground loop isolator->Left&Right RCA stereo RCA cable -> Left&Right RCA input.

I hope i declared myself correct or somewhat understandable.

XLR-RCA is also an option. To use XLR input on subwoofer amp and single ended RCA to receiver subwoofer preout.

Supra/Jenving are using Toroidal-transformers for low distorsion and wide frequency range.
@simon7000 suggessted Triad TY141. If i want to try and build my own i will need two of those then and 4 RCA female input connectors? Maybe some kind of test board or something to solder everything in or something similiar.
 
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I made a board for two TY250P transformers.

Driven from a low Z circuit, and with a zobel on the secondary consisting of a 1000pF cap in series with 1k5, it makes clean 20kHz square waves.

I have a some left.

2$ each plus postage if you're interested.
 

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Can you please post a link that would explain the basics of the line level ground loop problem and how you fix it? I definitely have some of it in my system. Unfortunately, I was unable to understand the discussion above lacking the basics to begin with. Thank you.
 
@Galu thank you it was very helpful! Now I know exactly what I have and why.
Now I also see from that article that because I have a very mild case of the ground loop, I can only hear it clearly like 1-2 ft from the speakers, I can try other options before trying the transformer.
My plan is to make all ground wires very conductive - I will double them down at the power cables, and make a thick wire in my DIY XLR cables. Also double down the ground connection inside the Furman power strip. The article is discussing something like that at the bottom.
 
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