Please help me understand the purpose of such a filter at DAC line output

[Anatolii_A]

Hi ! It is something about impedance matching or what else ? Capacitors value are so small that my multimeter shows 0.01nF that propably be an error, but it measures values about 5-10nF very well...

 

[TNT]

Isn't that a 4th order LP filter. It will remove HF residuals spit out by the DAC and its purpose is to protect any electronics downstream from this HF "garbage". That would be my answer.

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[Anatolii_A]

But which will be cut off frequency with 10pF in such filter if we assume it is just a filter? Lets think about multimeter error and it may be 5-20pF, but it measures well 510pF cap right now.

Perhaps this is just trick to show exactly 10K at RCA ?

 

[Anatolii_A]

Sorry, my mistake. In original schematics here is additional coupling cap. At the left side here is a circuit to headphones op amp. I use it without coupling caps so show wrong scheme in 1st picture.

 

[TNT]

100ohm and 10nF -> 160k.... Lets await the experts... 🙂 its probably only 2nd order...

http://sim.okawa-denshi.jp/en/CRCRtool.php

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