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Standard User Littleseen
(regular) Tue 04-Sep-12 16:51:36
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ground loop isolator


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I have a tower pc running XP with an Audigy-2 PCI sound card. The Nicole twin speakers are mains powered from the 230v AC mains feed into the tower and not from the pc's PSU, all normal enough. My mic of many tried is a dynamic into the sound card (a USB2 mic is hopeless)

The problem seems to be what I might (?wrongly) call mains hum. It spoils mic work. The more the volume is turned up in the sound card or on the volume knob on the speaker the louder the wretched hum. Killing the speakers at its own mute button stops the hum.

With the pc off and the mains suppy to the speakers on, the speakers hum & 'tis bad

If I record mic speech via the Audigy-2 Creative soundcard the hum is on the recording, cannot be got rid of, and saving to HD merely saves the speech and the hum as well.

I have tried a Maplins L07BK "mains isolator" --- costly, got my money back though --- which did nowt. It was supposed to clean up a dirty 230v AC mains supply being inserted in series upstream of the offending item. I expected nothing from it, read some very mixed reviews, and it quite failed to produce any blue smoke or a smell of frizzing.

But I did have hopes of Maplin's VW43 ground loop isolator. When rigged to 3.5mm stereo jacks I was able to insert it at various points into my system. This too did nothing.

Not technical, muggins here wonders if the Nicole speakers might themselves generate the hum? How can I tell without spending much £sd on something better, whatever better might mean. The hum btw is still present in any brand of earphones I try with of course the speakers muted.

Obscurity is a comfortable cloak
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