New external hard drive makes my Hifi buzz

[Parsfan]

Hi

Not sure if this is the right area to ask but.

I use my PC for music. All my mp3 are stored on my hard drive. I have my hifi plugged into the computer using a headphone jacl to phono lead. I plug the headphone jack in to the headphone socket of my PC and that runs to the phono in sockets on my hifi. Up till now it's worked well.

I decided to buy a new hard drive which would be specificaly for mp3's. I got an external 200 GB one. I'm sometimes asked to bring music to partys and with an external I can unplug it at take with me.

Anyway, the hard drive works great, very fast and quiet. The problem is as soon as I it in to the USB port the hifi starts buzzing. Unplg the hard drive from the PC and the buzzing stops.

If I plug my headphones directly into the PC sound card using the headphone socket things are fine, it's only the hifi thats the problem.

Is this a USB lead fault or the PC - Hifi lead fault. Are there leads available that would sheild the wires from any electrical disturbance.

[uripyores]

I had a buzz like you describe and I found that by connecting a separate earth/ground wire to the unit cut it out. It wasn't exactly the same thing as yours but it could be worth a try anyway.
[ignore if you have already done that]

[smurfy]

that runs to the phono in sockets on my hifi

And there is your problem.
The phono jack on most amps or pre-amps is the only one that cannot be interchanged for other inputs. If you have an AUX input, use that.
Others more qualified in the audio theory can probably explain why but I think it has something to do with the impedence or something (plus gou will normally see a ground pin for the phono as well - as uripyores mentions)

[Parsfan]

Thanks for the replies, sorry I couldn't get back sooner. I should have been a bit clearer, the leads are going into the aux socket at present i'm afraid. I've bought a new cable since then and it fixed one part of the problem but i'm still getting the buzz. I suspect that a better sheilded USB lead might help so will get one. If that doesn't work then i'm stuck again.

I've treid the separate ground wire as well with no success.

[Ned Seagoon]

Hi Parsfan

The problem you are talking about is caused by what is called an earth loop. An isolation transformer will solve the problem. The transformer needs to match the impedance of the two circuits it is connected to, ie the aux socket on your HiFi and the headphone jack on your computer.

See here for a diagram and some details.

A hifi or kit shop should be able to sell you what you need.

Good luck. BF

[Parsfan]

Thanks, thats brilliant. I had a search and found you can get the equipment for around £15-£20. Hopefully this will solve my problems.

The link was really useful.