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Buzzing 3.5mm stereo extender?

nelmr

Active Member
I bought a 12 foot 3.5mm (1/8 inch) stereo plug extender cable from amazon for about $3. I never have had any issues buying cheap cables but this time is different.

This cable is so that I can hide a cable run from my PC to my TV (then the signal gets run to my sub's x-over and finally to the audio engine A2 speakers via other cabling obviously). I currently have a 3.5mm stereo to RCA jacks cable that is 6 feet long. I was going to buy a 6 foot extender, but the 12 foot was just a few pennies more from the same manufacturer.

When I plug the 3.5mm to RCA cable into the line out of the PC I don't get any buzzing. When I use the 12 foot extender I get buzz. I also get crackle if I twist the 3.5mm jack on the extender at the PC line out connection. Depending on how I twist the cable the end resulting buzz can be slightly louder or quieter. If I do this with the 3.5mm to RCA cable I don't get any crackle or buzz.

Is this a bad extension cable?

Here is the cable I bought:

http://www.amazon.com/RiteAV-3-5mm-...6?s=electronics&ie=UTF8&qid=1295737264&sr=1-6
 

Yesfan70

I'm famous now bitches! vvvvv
Famous
Honestly, for $2.78 I would either just order another one and see how it does. If it gives you the same problem, then look elsewhere as you're only going to be out a little over $5 in the end.
 

Flint

Dog Faced Pony Soldier
Superstar
Sounds like a ground loop problem which is being remedied by a heavy ground (shield) wire when present but when the longer cable is used the shield wire resistance can vary depending on the bend or twist of the cable.

I'd get a newer, heavier extension wire. Check out Hosa Cables for a heavier, beefier model.
 

soundhound

Well-Known Member
Flint said:
Sounds like a ground loop problem which is being remedied by a heavy ground (shield) wire when present but when the longer cable is used the shield wire resistance can vary depending on the bend or twist of the cable.

I'd get a newer, heavier extension wire. Check out Hosa Cables for a heavier, beefier model.
Actually, wire gauge has nothing to do with how well a cable deals with a ground loop; in fact, a cable of any gauge is not going to stop a ground loop if there is the potential for one. Either there is a ground loop or there isn't; a ground loop is current flowing through the shield of a cable from two components which have grounds at different voltage potentials, and that current is then magnetically induced into the center conductor. All that heavier shielding of a cable accomplishes is to form a better electromagnetic barrier from interference arriving outside the cable from reaching the inner hot conductor - that is not the same thing as a ground loop.

I agree the solution is to get another cable, a better cable, but the problem is very likely contact resistance, not cable resistance. Cheap cables are notorious for using very cheap metal surface plating on the electrical connections. When you are turning the connectors, you are changing the electrical resistance, which generates a better and worse contact; the resistance of the wire is a constant, whether the cheapest cable in the world or the most expensive. Cheaper cables usually have less shield coverage than more expensive cables, which translates to worse protection from induced interference from external sources.

When there is a ground loop between two components, there are a number of things you can do such as making sure the devices are on the same 120V electrical circuit. I have cured ground loops by running a third physical wire (any gauge) from one chassis to the other so that the ground currents flow through this wire and not the audio cables. Other times a ground "cheater" plug works. Sometimes reversing the AC plug in the outlet helps, although all AC plugs now are keyed. At any rate, I would make sure the two components are on the same AC circuit, even if you have to run a 12' extension cord. Computers are also tricky beasts about generating various buzzes and other unwanted signals; in my very complex system I deal with these almost daily. Some mysterious buzzes come and go depending on the load on the pole transformer which supplies AC to my house and two others. Also, all the EMI/RFI which is generated by my neighbors goes straight through into my house wiring via the pole transformer which we share, then I have to deal with it by line filters / isolation transformers.
 
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