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-   -   non os measurement (http://www.diyaudio.com/forums/digital-source/86398-non-os-measurement.html)

Bernhard 12th September 2006 11:31 PM

non os measurement
 
This is about a partially filtered non os DAC.

First, music signal from an oversampling CD player, 31 kHz analyzer bandwith.
It can be seen the CD bandwith limitation of 22,5 kHz.

http://www.beautyphoto.de/music31khzos.jpg

Now the transformer + cap filtered non os DAC.
The empty space above 22,5 kHz is filled with harmonics.
Non os gives back a little of what the CD format has taken away.

http://www.beautyphoto.de/music31khznonos.jpg

Pink noise from CD with oversampling, 83 kHz analyzer bandwith.

http://www.beautyphoto.de/83khzpinknoiseos.jpg

Pink noise from CD with non os DAC.
It can be seen, at 80 kHz HF is pretty much down.
That should not be a problem for a good amplifier.

http://www.beautyphoto.de/pinknoise83khznonos.jpg

Bernhard 13th September 2006 12:50 AM

1 kHz full scale sine non os.
There is the rest of the HF visible.

http://www.beautyphoto.de/nonos1khzsine.jpg

FFT of the sine, analyzer bandwith 10 kHz, 94dB vertical scale.
The k2 harmonic is caused by the passive I/V.

http://www.beautyphoto.de/fftnonos.jpg

Same with 100 kHz analyzer bandwith, the 44,1kHz and 88,2 kHz are split, jitter :confused: :eek:

http://www.beautyphoto.de/fftnonos100khz.jpg

Werner 13th September 2006 06:24 AM

Quote:

Originally posted by Bernhard
The empty space above 22,5 kHz is filled with harmonics.
Non os gives back a little of what the CD format has taken away.
These aren't harmonics, and thus these aren't what 'the CD format has taken away'.


Quote:

Originally posted by Bernhard
Same with 100 kHz analyzer bandwith, the 44,1kHz and 88,2 kHz are split, jitter :confused: :eek:

Baseband frequency f creates images at every N*fs+f and N*Fs-f,
so 1kHz has images at
44.1kHz-1kHz
44.1kHz+1kHz
88.2kHz-1kHz
88.2kHz+1kHz
...

Bernhard 13th September 2006 09:12 PM

Quote:

Originally posted by Werner

Baseband frequency f creates images at every N*fs+f and N*Fs-f,
so 1kHz has images at
44.1kHz-1kHz
44.1kHz+1kHz
88.2kHz-1kHz
88.2kHz+1kHz
...

Thanks :blush:

Still, there is something above 22 kHz and maybe it makes a difference. Perhaps.


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