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Ethernet Cable Audio Extension

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CAT5 Ethernet cables to connect audio from my PC to my room stereo.  My shop has a nice stereo on the far wall away from my PCs and work bench. Rather then purchase a long audio extension cable I scrounged up some CAT5 Ethernet cable and audio connectors, a few quick splices and a 30 foot audio cable is born. Sounds great!


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A few hundred feet of CAT5 cable left over from a home networking project. Saved so the wire could be recycled.

Just measure out the amount you need, leave some slack for mistakes and cut to length.




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RCA audio cables and a small stereo headphone jack also scrounged from a previous audio project where they were scrounged from some left over audio cables.

To splice the audio cables to the CAT5 start by picking two pairs of wires, I used the Brown and Orange pairs for Left and Right audio.

The wires are soldered and each connection is staggered to prevent shorts.

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After building the cable check it with an Ohm Meter to make sure its correct. Then install.



RJ45 Pin# Wire Color Function Headphone Jack RCA
1 Orange/white Right Ground Sleeve Red Outer
2 Orange Right Audio Ring(red) Red Inner
3 Green/white
4 Blue
5 Blue/white
6 Green
7 Brown/white Left Ground Sleeve White Outer
8 Brown Left Audio Tip (white) White Inner

Posted in Discovering, Hacks, Ideas, Parts, Projects, Scrounging, Scrounging Parts, Workshop Tips.


10 Responses

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  1. Florin says

    It always feels good when you can recycle something. Even nicer when it’s electronics :-)

  2. Anon says

    with plenty of wires left over to run a 100Mbit network over there too… if you wanted :D

  3. admin says

    @Anon Yes 100 MBit Ethernet only uses two pairs (4 wires) of the 4 pairs available (8 wires) We could use the other wires to route signals between the Ethernet jacks. I’m sure we can think of some good uses.

    I’m thinking a serial home control network.

  4. David says

    This is a clever idea, but there’s no such thing as a free lunch, and that applies here as well. CAT5 twisted-pairs are low-impedance balanced cables, whereas, consumer and semi-pro audio signals and cables, as well, are high-impedance unbalanced (i.e., the signal is referenced to ground). This probably won’t matter over short distances in low RF environments, but if you try more than a few few in an urban setting, this is going to be a disaster. You really need a balun, which is a transformer that converts from unbalanced-to-balanced on one end of the CAT5 and then another balun on the other end. Check amazon.com for “niles balun” to handle audio, video, etc. Unfortunately, these things are not cheap, nor are they completely transparent because iron coupled inductors with parasitic capacitance are going to cause unwanted filtering of the audio signal. So, just like other fields of pseudo-science and pseudo-medicine, sometimes it’s best to trust the experts. In this case, good shielded high-impedance unbalanced audio cable will be a bargain in the long run.

  5. A name is required says

    Why do you think they put shielding on the RCA cable – for amusement of the manufacturers?

  6. admin says

    Hey thanks for the comments, I am a EE myself so I understand and agree, would be better to use shielded cables and matching, but this was an experiment to see how well CAT5 would work for about 20 feet. I cant hear the difference between this setup and the one I had before with an Airport express from ITunes. At least now any sound source works to drive my stereo.

  7. admin says

    OH and I should add that I am an avid listener. Driving two Warferdale speakers with about 200 Watts each, they are just barley warmed up at that. It seems that while the Ethernet cable is not the ideal solution, its not easy to hear the difference even with great listening equipment.

  8. admin says

    Yes it amuses the manufactures greatly to put shields on audio cables. You should see them laughing so hard their false teeth fall out over that little white strip they put on speaker zip wires. They really do have a great time with that stuff.

  9. Berni says

    CAT5 cable is about the most useful kind of cable there is. Its perfect for making breadboard jumpers or wiring up your DIY projects.

    I always keep a length of CAT5 cable handy.

Continuing the Discussion

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