Ground Loop From Computer

[Adam_G]

I've recently been using a Marantz receiver that I borrowed from a friend, but it's really irritating me that I can't get rid of a ground loop issue. I've been using my computer and running signal to receivers in the same setup and never had the buzzing be this bad. Nothing other than the receiver has changed.
No matter what I do, if the volume is muted or at 100%, I get a constant buzz in my signal that plays through the speakers. If I disconnect the cable (a standard headphone cable) the buzzing instantly stops, so it's not interference in the cable. Any clue what may be causing this issue? Or how to fix it?

[billfitzmaurice]

Re: Ground Loop From Computer

Any clue what may be causing this issue?

I assume this only happens when on AC. If it still happens when on battery then there's something wrong with the receiver.

[Adam_G]

Re: Ground Loop From Computer

Yes it's AC, it's a desktop computer. If I plug in my phone or something to the same cable I don't have any issues.

[billfitzmaurice]

Re: Ground Loop From Computer

Yes it's AC, it's a desktop computer. If I plug in my phone or something to the same cable I don't have any issues.

You probably will have to transformer isolate the signal cable from the receiver. You don't have issues with a phone because it's not connected to the AC ground.

[Face]

Re: Ground Loop From Computer

Use the optical out from your motherboard.

[Adam_G]

Re: Ground Loop From Computer

You probably will have to transformer isolate the signal cable from the receiver. You don't have issues with a phone because it's not connected to the AC ground.

How would one go about that, preferable on the cheap.

[1100xxben]

Re: Ground Loop From Computer

How would one go about that, preferable on the cheap.

Don't have a clue on the quality, but here's an inexpensive solution.

This is a little pricier, but at least they claim 20 Hz -20 kHz +/- 0.1 dB.

Something that is even more expensive, but I can definitely vouch for would be Jensen transformers. The DIN2-LI would get you stereo isolation with pretty much ruler flat FR and miniscule distortion, but you'll pay for it at $200+

[Adam_G]

Re: Ground Loop From Computer

Use the optical out from your motherboard.

Unfortunately my motherboard doesn't have an optical output, otherwise that'd be first on my list.

I'm hoping my power supply isn't crapping out. I figure the AC noise should be filtered as the computer runs on DC power internally, but it may be a case that it is grounding to the frame or something like that. I'm not quite sure. :(

[kevin007]

Re: Ground Loop From Computer

buy a power supply tester. you get them at fry's or another electroic show. you most likely have a bad PSU.

[Paul O]

Re: Ground Loop From Computer

This is a very common problem with computers, and the Behringer HD400 and other such devices do a great job of eliminating the problem. http://www.musiciansfriend.com/pro-a...ehringer-hd400

[billfitzmaurice]

Re: Ground Loop From Computer

Unfortunately my motherboard doesn't have an optical output, otherwise that'd be first on my list.

I'm hoping my power supply isn't crapping out. I figure the AC noise should be filtered as the computer runs on DC power internally, but it may be a case that it is grounding to the frame or something like that. I'm not quite sure. :(

The problem isn't bad grounds, it's too many grounds and unbalanced transmission. This explains:

http://www.rane.com/note110.html

[PEB]

Re: Ground Loop From Computer

Are the PC and receiver on the same wall outlet?

[Johnnycat]

Re: Ground Loop From Computer

Have you tried a USB to analog converter like http://www.parts-express.com/pe/show...number=230-110

[Adam_G]

Re: Ground Loop From Computer

Are the PC and receiver on the same wall outlet?

No, they aren't. They're actually in different rooms with about a 20ft cable run apart. I was thinking of somehow running them off of the same outlet, but I'm not quite sure of the logistics of that.

[Adam_G]

Re: Ground Loop From Computer

Have you tried a USB to analog converter like http://www.parts-express.com/pe/show...number=230-110

I haven't, and the only reason I haven't is that if I get something like that I'm going to go with an external sound card with optical output, and I'm hesitant because of the money it would take and the fact that I have 5.1 outputs on my built in sound card as it is, so the money wouldn't be the best spent.