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

Robin Gareus robin at gareus.org
Fri May 28 15:05:19 UTC 2010


On 05/28/2010 02:31 PM, fons at kokkinizita.net wrote:
> Hello all,
> 
> This week I had to perform measurements on a audio
> interface, and this resulted in some quite interesting
> results. Before revealing what happened, I'll let you
> have a look at some of the data and come up with your
> own conclusions, see
> 
> <http://www.kokkinizita.net/linuxaudio/quiz.html>
> 
> (Free beer at the next LAC for the best analysis)
> 
> Ciao,
> 

Well, interpreting an 'experiment' that one has not conducted
him/herself without knowing _all_ parameters of the setup is not
something to encourage doing..

Did you use symmetric (XLR) connections? Are the sample-rate settings of
both cards identical? what was the physical distance between the devices
(cross-talk)? Was there any ground-lift equipment (built-in?) in place
or maybe you simply forgot to switch off phantom-power?

Anyway, good that you've labeled it 'quiz'; so here's my guess:

You're encountering reflections (or even standing-waves) in the cable.
(did you uncoil it? or was it a very short one?)

Did you repeat the measurement? using different cables for example.

Cheers!
robin



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