MagicianT

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  1. It's a pity, that X5R type of capacitors was used in the audio path. Cirrus Logic missed to put a note into CS4344 data sheet on this occasion, as they did for CS4354 https://statics.cirrus.com/pubs/proDatasheet/CS4354_F3.pdf page 12, figure 5: I can add, that even common aluminium electrolytic capacitors would be better choice to keep THD at low level.
  2. In my first message, I mention than if you open schematic from this link: https://reference.digilentinc.com/_media/reference/pmod/pmodi2s2/pmodi2s2_sch.pdf you see that C4 & C5 at the OUTPUT of the DAC CS4344. Outputs left & right channels were loaded with standard 47k impedance of the USB sound card. I have another codec from the same manufacturer (Cirrus Logic) CS4354 that doesn't require DC blocking capacitors, and I'm pretty sure my test setup is perfect, since I get -94dB THD running two codecs in parallel simultaneously. Same data bus, same clock etc. Since DAC are always slaves on I2S, nothing prevents line up 2 or more units for comparative testing. I would expect same issue for the INPUT to ADC CS5343 ( C14 & C15), but I didn't test this part yet.
  3. I 'd like to refer to TI, page 5, 6, 7 https://training.ti.com/system/files/docs/1324 - Low Distortion Design 4 - slides.pdf or Maxim-IC https://pdfserv.maximintegrated.com/en/an/AN4333.pdf Those docs explain in details why X5R & X7R are NO-GO into audio design, especially with high quality codecs (-100dB THD level). My test setup shows almost -40 dB for 2-nd harmonics at lower frequency end, and -80 dB in the middle band. It's not even close to what I was expecting reading cs4344 data sheet.
  4. Hi, Is there any info I can get on the type of components for PmodI2S2 codec module. I observed unusually high THD level at the DAC outputs, that make me think about C4 & C5 (3.3uF).