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Old 05-10-2011, 03:18 AM   #25
Dannii
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Join Date: Mar 2010
Location: Adelaide, South Australia (originally from Geelong)
Posts: 5,598
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Quote:
Originally Posted by dungbeetle View Post
Well, I finally managed to try out both the ground loop isolator and the star grounding method over the weekend.

The isolator definitely improved matters, reducing the noise through the speakers to an acceptably innocuous hiss. Interestingly though, it only seemed to do its job while the amplifier volume was set to around 75% or less. Any higher than that, and it was as if it could no longer take the strain and all the nasty noise came bursting through again.

The thing that surprised me about this, was that it wasn't a gradual increase in noise when it eventually gave up the ghost. Tweak the dial to just over 75% and POW!, the floodgates opened and all the noise broke through. Turn the volume back down again and all is good. Strange.

With regard to star grounding, unfortunately it didn't seem to make much difference for me. I suspect that either I'm doing it wrong or there's just too much electrical equipment plugged into the lounge ring main, wreaking havoc.
A star earth setup won't solve the problem of noisy laptop power supplies in most cases. The problem here isn't a potential difference in the mains wiring due to wiring resistance, it is noise induced by the laptop and it's PSU finding it's way into your monitors via the ground connection. Somewhere along the path, you have to isolate the mains earth from the audio earth and break the loop between the laptop and the monitors. The only thing I have found that does this reliably is to remove the mains earth connection from the PSU.
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