Besides the THD+N it could be interesting to see the THD, so without the noise.
Have you considered making the PCB compatible with the AK4493? It only requires a small additional effort.
I have not but I should check it, I did notice its existence a while ago.
I do have THD results as well. Here is a graph from the VREF=5V case, from the same run I posted before the THD+N. At 0 dBFS THD+N is pretty much dominated by THD as can be expected, below that noise contributes more.
I could maybe extract more numbers from there but the lowest values are somewhere in the -116..-118 dB ballpark (and again, I forgot to change % to dB..).
Jens, you got to the better side of -120 dB with your analyzer?
In fact, I did not check THD only numbers with large extra capacitors so this is something I should still check. Too many variables!
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Yes, at -20dBFS I typically get just below -120dB THD.
Perhaps you are limited by the AP analyzer? It looks like your results are limited by noise. I normally use a large FFT window (512k) to suppress the noise floor in order to see the harmonics.
Perhaps you are limited by the AP analyzer? It looks like your results are limited by noise. I normally use a large FFT window (512k) to suppress the noise floor in order to see the harmonics.
However, this is the first project for me that I am thinking of running a small batch assembly of so BOM cost is one figure to pay attention to here.
I'm interested. I would buy two and use it together with a SigmaDSP in an active loudspeaker I'm working on. Then the modular approach with a DAC PCB with just I2S inputs would work great.