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Dac+ pro sine waveform

Hi all,

I have been doing some analysis of the hifiberry dac+ pro. I am in no means an expert so my apologies upfront if information is lacking.

What I observed is a sine wave that is not smooth and I am interested in how to improve the output of the DAC+ pro.

The reason for this post is to broaden my understanding of the workings of the dac+ pro and DACs in general.

I have generated a tone of 45Khz and exported is at 92khz and 196khz sample rate. The Tascam only goes up to 92Khz, but I tried both signal types on the DAC+ pro, it did not change the results.

I set up both the DAC+ pro (on a raspberry 4) and the Tascam DR-60DMK2 as a comparison.

What I've found on my scope is the following output of both devices:

I am interested in the cause of the non-smooth sine wave on the DAC+ pro compared to the TASCAM. Any suggestions or toughts are very welcome in my journey towards understanding the workings of this device better.

For further discussion, I have another question: Have does the DAC even know to put out such a constant sine wave, while the .wav datafile seems to be very imperfect at the 96khz sample rate for such a high frequency signal (45Khz).

To illustrate, here is the tone in Audacity at 96Khz and 384Khz.

Looking at the top signal, how does the DAC even know to put out a constant sine wave? I would expect a sine wave that varies a lot in amplitude, as the top signal realy seems to be doing.

I hope people find this information interesting and I am very much interested in your views on these topics.

Best regards,

Stefan

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