Bill Whitlock from Jensen gave a presentation to the AES group in Los
Angeles 3 months ago on Common Mode Rejection in Real-World
environments, If you're interested in learning more about how to combat
the "hum" in your audio, check out his information page, there's
multiple application documents and an AES document (which they usually
charge for) he has posted about dealing with noise in audio setups. Some
of them are a lengthy read, very informative though even if you decide
not to buy this products. Bill gives speeches regularly, if you can
catch him at a presentation go check it out.
http://www.jensen-transformers.com/apps_wp.html
BTW: AES meetings are always free to attend.
On 9/18/2010 12:51 AM, david wrote:
Alex Tinsley wrote:
First off any noise that you hear through your USB Audio interface is
because the grounding in the audio device is using the grounding on
the laptop which is most commonly data ground wired to earth ground.
So you hear all computer noise through the audio output. One way to
alleviate this is to lift the ground on the laptop (unplug the power
adapter from the laptop or get a ground lift adapter). Noise goes
away. A lot of devices suffer from this, 1394 has same issue.
I only get noise on my USB soundcard when I plug it into my external
hub. I get no noise with it plugged directly into the laptop. I guess
the laptop ground is OK and the external hub's ground is junk.
The hub has other devices plugged into it, I don't recall if I tried
using it with only the soundcard. Wouldn't be surprised if some of the
other USB devices on the hub (scanner, printer, MIDI interface,
PS/2<>USB adapter for keyboard & mouse, flash card reader) are sources
of noise by themselves.
Thanks for the extensive info!
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