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Thread ID: 34791 2003-06-24 03:56:00 USB Microphones - Laptop Power Supply Noise Problems Perigrin (4081) Press F1
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154655 2003-06-24 03:56:00 I have just purchased an ANDREA NC 7100 USB Mike to use with Dragon Naturally Speaking V6.0

It was touted as the answer to the Laptop users prayers as it by-passes the sound card.

However I get worse results from this than I ever did from the normal mike. This is due to 50 Hz noise from the power supply

I get good results when working on battery but this is not an option for obvious reasons.


Does anyone have a solution to this problem ?
Perigrin (4081)
154656 2003-06-24 05:58:00 I am surprised that a laptop power supply emits much 50 Hz EMI, as they usually employ switchmode technology that emits a much higher (several kHz) frequency.

Transformer based power supplies would be a problem, but I have never encountered one on a laptop. I wonder if its due to capacitive coupling with the 50 Hz, as these power supplies do not use an earth?
godfather (25)
154657 2003-06-24 19:52:00 You could well be right - I would not have a clue - I am truly clueless in this area.

Could you speculate on a cure, or a way to mitigate the problem?
Perigrin (4081)
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