low pass filter for DSD

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#43
look at the DSD1794 datasheet, it shows the internal schematic that includes the output filter, but you will need to work out the cap and resistor values for your system.

regardless you will be connecting USB ground as your analogue system ground, that doesnt sound like a great idea. I think the only viable options for this sort of circiuot involve much more involved filtering, power supply and isolation than a simple resistor and cap.
 
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#45
no problems, sorry I just double checked the DS, it mustve been somewhere else I saw the internal schematic, but if you look at page 37 of the DSD1794 datasheet, you can see the different output filter values for DSD mode which gives you a good starting point. notice for PCM and DSD mode the first section is the same, but the bal-SE section filter values are quite different
 
#49
Grazie ho capito tutto. Thanks I understand all.
 

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#58
abraxalito said:
Butterworth or Chebyshev would be fine - I suggest Butterworth as its simpler to design. The corner frequency depends on you - perhaps 50kHz -3dB would be fine as a first attempt.

A 4th order LC would have two series inductors and two shunt capacitors, followed by a resistive termination

<edit> Attached a schematic based on a design I did for an ESS DAC. Its Butterworth but 30kHz -3dB.
Click to expand...

abraxalito said:
Had a look, could not see any DSD outputs marked. Assume the output impedance is low - so use a 180R series resistor at the input to the filter (rather than the 195R shown). Remember it has 6dB attenuation in the passband.
Click to expand...

Could I use 160R in place of 180R?

346093d1367484624-low-pass-filter-dsd-merlinlc.png
 
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