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Insights into DAC specs and related graphs?

Tony C.

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Greetings! This is my first post, but I am long time lurker, and have developed more than a few systems over the past ~45 years.

Note that I have learned quite a bit through your forum already, and have made an effort to research the significance of the various specs and graphs that are typically used when analyzing components. But I have no science background, and have thus far only owned one stand-alone DAC, so I would appreciate any insights that readers might be able to provide into these measurements, which relate to a particular DAC. I think that it might be useful not to reveal the make and model, as I'd prefer to focus solely on the practical ramifications of these measurements. In other words, whether the DAC is overpriced or not is of little interest to me – I simply want to learn about how to best interpret these type of measurements, and, more specifically, I find this jitter frequency graph difficult to interpret.

Thanks in advance!

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amirm

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Welcome to the forum. We can't see those graphs. If they are from somewhere else, right click on the image and copy the "image source." Then here, use the image icon and select the link (paperclip) and paste the link. The image should then show.

If they are graphs on your computer, simply click on the image in the folder and drag it into your message and it should appear.
 

MZKM

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For Blue/Black:

That’s THD+N vs level, it however is going in reverse order of how we are used to with max output on the left. That graph shows that the DAC is overrun by noise from its minimum level up to around -20, after that is where distortion starts becoming prominent. As such, around -20dB is the best performance for that DAC in terms of THD+N, so if that output level is sufficient to drive your system, that is where I would keep its volume.

For Red/Black:

That is showing jitter, aka how precise & accurate the internal clock is. Spikes other than the center one are unwanted, and the further away from the center spike they are the more audible the are (think, you probably can’t hear the difference between a 1000Hz note and a 1005Hz note, but you for sure could if instead it was a 2000abs note) , so if they do exist you want to make sure they at least aren’t high in level.
 
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Tony C.

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Thank you, @MZKM

While I understand that in theory, DACs should be designed to convert and output as accurate a signal as possible, it seems that some designers, like some amplifier designers, attempt to "shape" the sound. Might such efforts contribute to higher levels of distortion?

To help me understand the jitter graph, and your related comments, here is a similar one, relating by a different DAC, but seen through the same software.

While there are spikes, the main pattern seems to be tighter, and better organized. Would that imply a cleaner reproduction? Or would the fact that there are spikes away from the center in both suggest similar, audible degradation (if any)?



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Killingbeans

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While there are spikes, the main pattern seems to be tighter, and better organized. Would that imply a cleaner reproduction? Or would the fact that there are spikes away from the center in both suggest similar, audible degradation (if any)?

It's cleaner measurements, but the worst case dirt is at -115dB. That's already a seriously low percentage. Audibility of that is questionable at best.
 

MZKM

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it seems that some designers, like some amplifier designers, attempt to "shape" the sound. Might such efforts contribute to higher levels of distortion?
Shaping the sound would be best done by actually altering the frequency response of the amp. Playing the distortion game is debatable wether it works, especially as the distortion of the speaker would be an unknown variable that the amp designer can’t plan for.
 
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Tony C.

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Shaping the sound would be best done by actually altering the frequency response of the amp. Playing the distortion game is debatable wether it works, especially as the distortion of the speaker would be an unknown variable that the amp designer can’t plan for.

Good points, thanks.

With regard to the contrasting jitter graphs, would you consider either, or both, to be potentially problematic from a practical/audible standpoint? And if the answer is "no", then I am wondering what, if any advantages DACs which measure exceptionally well might enjoy over those such as the examples shown.
 

MZKM

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Good points, thanks.

With regard to the contrasting jitter graphs, would you consider either, or both, to be potentially problematic from a practical/audible standpoint? And if the answer is "no", then I am wondering what, if any advantages DACs which measure exceptionally well might enjoy over those such as the examples shown.
I can’t tell the level of the center spike, so hard to discern how low in level the other spikes are (it’s always good form to have the test tone be at 0dB, to make comparisons easy). But, jitter is typically a not an audible issue, and if you had a DAC with such poor jitter that it became audible, likely other aspects of that DAC are terrible too. But, if you don’t know, audible jitter just sounds like noise.
 

Killingbeans

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With regard to the contrasting jitter graphs, would you consider either, or both, to be potentially problematic from a practical/audible standpoint?

No. Again, consider what -115dB means.

And if the answer is "no", then I am wondering what, if any advantages DACs which measure exceptionally well might enjoy over those such as the examples shown.

None, other than bragging rights.

Here's a 173 pages thread meant for that discussion:

 
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