Ground Loop Troubles

[Ditiris]

Okay, here's the deal. I have a receiver, and a computer. I want to hook up my computer's sound card to the receiver in order to hear the computer's sound on my home theatre system. I rolled my own RCA cables (they're unshielded, but I don't think that's the problem), and I got a nice 60Hz hum, although the sound was there and clear, just accompanied by the 60Hz hum. There is no way to hook up the computer and the receiver to the same power outlet. I tried getting a ground loop isolator (I bought it from radio shack) and the damn thing cancelled ALL the sound. Someone, for the love of God or your selective deity, please help!

 

[zogg]

can you reverse the polarity of the stereos power cord? just a thought.

 

[Workin']

If both are plugged into the wall using a 3-prong plug, try using a "groundbuster" (you know, one of those little 49 cent adapters that lets you plug a 3-prong device into a 2-prong outlet) on ONE of them.

Are you sure you connected the ground loop isolator properly? I've never heard of the result you got......

I doing these things or what zogg suggested doesn't fix the problem, then I would suspect the cables you made are better antennas than patch cords. Actually, that's the first thing I suspect.

Good Luck! Ground loops can sometimes be a b!tch to isolate.

 

[DaddyG]

Why did you 'roll yor own RCA cables'. I've done this lots of times but always used pre-built cables with an adapter for the mini-plug on the Sound Card.

 

[Ditiris]

First, let me say I'll try the prong-adapter.

Now, to answer the other question. The reason that I rolled my own cables was because a prebuilt cable costs an assload of money. I would also have to buy adapters since I know of no place that sells prebuilt RCA cables that are approximately 60 feet in length (to connect the shorties together). The longest I've ever seen are 20 feet, mostly because people are just hooking up home stereo components. Plus, all the stores around here in Dallas only sell those stupid Monster cables, which run around 50 dollars for 20 feet. I can't afford that, gold plated connectors or not. I used some of the speaker wire I bought when I rewired my home theatre system, which cost around $0.005 per foot. Throw in the mini-plug for the sound card (.35) and two RCA connectors (.30) and I make out just a bit better with rolling my own RCA cable. That's a $1.25 total, for those of you counting. Plus, I like to solder things.

 

[FOH]

"I rolled my own RCA cables (they're unshielded, but I don't think that's the problem)"


Unshielded cables are the MOST likely problem. If the cables are anywhere near power cords they can pick up 60Hz hum. (sometimes they don't have to be very close at all). Try re-making the cables with GOOD quality sheilded cable. (You said you like to solder things.) When I say good quality I don't mean you have to spend a fortune on those "audiofile" cables, just get 100% shielding. Foil shielded cables are good.