Re: [LAD] A little quiz about audio measurements...

From: Ralf Mardorf <ralf.mardorf@email-addr-hidden-dsl.net>
Date: Fri May 28 2010 - 21:29:50 EEST

Niels Mayer wrote:
> On Fri, May 28, 2010 at 8:37 AM, <fons@email-addr-hidden> wrote:
>
>> On Fri, May 28, 2010 at 08:30:54AM -0700, Niels Mayer wrote:
>>
>>> [...]
>>>
>> You're close. See the extra hint in a previous post.
>>
>
> It the "close" has to do with jitter:
>
> * Something on the USB bus is causing a "periodic jitter" with a cycle of 100Hz?
> * Something is causing a buffer to become empty every 0.01 seconds and
> causing a periodic desync?
>
> If the "close" has to do with induced or actual 50hz hum, perhaps
> frequency-doubled via rectification:
>
> * something in the USB power supply, as well as how that power supply
> floats w/r/t ground (ground noise) is the source.
>
> Which would agree with the Wolfson experts from
> http://wolfsonmicro.com/uploads/documents/en/Specifying%20Jitter%20Performance.pdf
> stating "One of the authors once spent several days trying to track
> down a low-frequency jitter problem, only to find that it was in fact
> a problem of LF noise on the voltage reference."
>
> Niels
> http://nielsmayer.com
>

Don't forget to argue for what card. A or X?
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Received on Sat May 29 00:15:08 2010

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