linuxaudio.org

Ralf Mardorf wrote:

quoted text
> Gabriel M. Beddingfield wrote:

>>

>>

>> On Fri, 28 May 2010, Folderol wrote:

>>>

>>> Once you connect the analogue side of the the USB device to the

>>> installed (high quality card) you have an earth loop that traverses

>>> both the analogue and digital domains. You also have an +5V loop

>>> (unless

>>> the USB device is externally powered) This loop does not exist when the

>>> USB card is self testing. I still can't think exactly how, but I

>>> believe this is likely to be a significant part of the problem.

>>

>> OK... but ground loops usually produce noise or a DC offset, right?

>> What could be causing the ground loop to oscillate?

>>

>> -gabriel

>

> Somebody ask for ground lift

The switch, for totally cutting or decoupling by a capacitor.

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