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Old 3rd September 2010, 08:54 PM   #11
Tenson is offline Tenson  United Kingdom
diyAudio Member
 
Join Date: Feb 2006
Location: Kent
Hi,

Digging up an old thread. I downloaded the J-TEST file and ran it through my DAC and FFT'd the output, but I don't really understand hat to look for. Can someone explain to me how to read this and calculate the jitter?

Do I just look at the two direct side-bands of the 11025KHz signal, or is there more to it?

Here are my results.

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Old 1st November 2010, 02:07 PM   #12
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by Tenson View Post
Digging up an old thread. I downloaded the J-TEST file and ran it through my DAC and FFT'd the output, but I don't really understand hat to look for. Can someone explain to me how to read this and calculate the jitter?
cMP² | CMP / 03Jitter

The above contains references and formulas.

http://www.stereophile.com/digitalpr...rs/index4.html

This from stereophile has some practical data and interpretation.

Quote:
Originally Posted by Tenson View Post
Do I just look at the two direct side-bands of the 11025KHz signal, or is there more to it?

Here are my results.
Well, the two highest sidebands will likely determine the overall jitter level (looks like around 400ps PP eyeballing it, decent enough for 14 Bit digital...).

On the other hand RMS and/or PP Jitter measurements relate to it's audibility about the same as single number THD Measurements do.

It seems your DAC also has a lot of 50/100Hz Hum (and upper harmonics), worse than my TDA1541 DAC with Tubeoutput stage (which is not particulary quiet) and higher jitter as well.

Ciao T

Last edited by ThorstenL; 1st November 2010 at 02:10 PM.
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