Fair enough. I mean, loudspeakers and room refection phase noise dwarfs this by orders of magnitude. The question is why is it being talked about in this thread? It seems very unlikely it's the reason people say DAC X sounds better than DAC y.
Ok so one is jitter which is measured frequently and the other is t and is not an issue anyway. So what was your point again?
I have Mark muted as he was talking a lot of random noise I have no time for.
If the following answer doesn't make any sense to you, please read the Wikipedia articles on phase noise and on mixers, https://en.m.wikipedia.org/wiki/Frequency_mixer , and try again.
The phase noise floor matters because a DAC inherently works as a mixer in the RF sense of the word. If there is high-frequency noise on the voltage reference or the clock, it converts out-of-band quantization noise (*) into the audio band.
(*): which isn't really noise, but let's skip that for the moment.
I brought close-in phase noise up just as an example of differentiating properties that are not measured.
My view on the topic is that unless I can confidently identify dacs in AB test I don't consider there to be an objective difference which also means I cannot have an objective preference based on audibility. BTW none of the alternatives given in the topic fits this view.
My view on the topic is that unless I can confidently identify dacs in AB test I don't consider there to be an objective difference which also means I cannot have an objective preference based on audibility. BTW none of the alternatives given in the topic fits this view.
some 15 years ago wanted to decide between two dacs in the 2000 euro category and was perplexed how different they sounded on the same hifi chain.
This frustrated me so much I never ever bought any expensive gear any more.
This frustrated me so much I never ever bought any expensive gear any more.
I was simply trying to answer your question from post #81, but apparently didn't do a good job at it.
That's a pity, because he also gave some good replies. Besides, it makes it more difficult to follow discussions between Mark and me.
Far too much waffle mixed in with it. He seemed to be getting a kick out of doing it so he's muted.
It contributes to the noise floor, so when you play silence at a high enough volume setting, it will be audible.
It will also be quite measurable and will be routinely measured. My comment about different types of jitter was a reply to a remark of Mark, not to the original question of this thread.
Define "measure as audibly transparent"
Mark, I don't know if you ever read Steven R. Norsworthy and David A. Rich, "Idle channel tones and dithering in delta-sigma modulators", Preprints of the 95th Audio Engineering Society conference, preprint 3711, October 1993. It's 31 years old so it doesn't address the latest and greatest sigma-delta DACs, but you might find it interesting anyway, because it deals with nonstationary noise. It took me a while to understand why their Fig. 9 is not a horizontal line at 0: it's because the graph doesn't show the autocorrelation, but a numerical estimate of the autocorrelation. That numerical estimate has larger variations in the peaks of the nonstationary noise.
Phase noise is a property of an oscillator (aka clock) but phase error/distorsion is a property of e.g, an analog output of a DAC. A high level of phase noise of a used clock manifest itself as basically distortion on the analog output of a DAC but not a phase error. To be very clear: PN in clock don't do phase faults in sound.
To discuss PN is an impementation aspect of trying to lower a user experiance aspect as distortion.
There should be possible to measure the impact of PN on the analog side... but "we" seem not to know how.... or at least dont...
//
Maybe I am being somewhat naive, but it strikes me that “proof of audibility” ought to be somewhat testable - although not necessarily by me at this point.
In one of Douglas Self’s books he shows a test setup where the output of two amplifiers is subtracted and that difference signal is then amplified and fed to a speaker. If no sound emanates from the speaker then the amplifiers must therefore sound the same.
That nice simple picture gets a bit fuzzier where DACs are involved as synchronization of the audio signal between DACs is going to be problematic due to differing latencies between devices especially where dsp is involved and different buffer sizes are in use.
So I had an idea for tackling this. How about if the output from one DAC was recorded on a suitable high quality ADC and the resulting WAV file is stored.
Repeat for 2nd DAC.
Adjust for timing issues with a reference signal at the start, the subtract the two files.
Play the subtracted file.
What you are now hearing is the difference in sound between the two DACs.
There are clearly several possible objections regarding issues in the ADC and what DAC to use for playback, but this does seem like a plausible path to an answer. Issues wrt to bit rate and depth would need to have some consideration also.
Just for the record, I believe that I can hear differences between DACs. However that shouldn’t be too surprising given that my DACs are all low cost and have wildly different specifications.
My most expensive and exotic DAC uses the ES9018, (Xduoo MU604), and is by no means expensive at around €170. It is also the best sounding.
Perhaps I still have a long way to go on my journey to DAC heaven!
Is my idea too flawed to be useful?
Thoughts?
In one of Douglas Self’s books he shows a test setup where the output of two amplifiers is subtracted and that difference signal is then amplified and fed to a speaker. If no sound emanates from the speaker then the amplifiers must therefore sound the same.
That nice simple picture gets a bit fuzzier where DACs are involved as synchronization of the audio signal between DACs is going to be problematic due to differing latencies between devices especially where dsp is involved and different buffer sizes are in use.
So I had an idea for tackling this. How about if the output from one DAC was recorded on a suitable high quality ADC and the resulting WAV file is stored.
Repeat for 2nd DAC.
Adjust for timing issues with a reference signal at the start, the subtract the two files.
Play the subtracted file.
What you are now hearing is the difference in sound between the two DACs.
There are clearly several possible objections regarding issues in the ADC and what DAC to use for playback, but this does seem like a plausible path to an answer. Issues wrt to bit rate and depth would need to have some consideration also.
Just for the record, I believe that I can hear differences between DACs. However that shouldn’t be too surprising given that my DACs are all low cost and have wildly different specifications.
My most expensive and exotic DAC uses the ES9018, (Xduoo MU604), and is by no means expensive at around €170. It is also the best sounding.
Perhaps I still have a long way to go on my journey to DAC heaven!
Is my idea too flawed to be useful?
Thoughts?
Amir at ASR does this for cables. Here is a video where he tests an expensive power cable this way:
Maybe it is not all in the digital. As an avid DAC builder I made a series of prototypes of the simple Subbu DAC. I measured them all for anomalies and was hinted that regulators sometimes oscillated because of ceramic caps. This turned out to be an issue depending on brand/type of X7R ceramic caps. Changed that in all to the same decoupling cap (tantalum) and reviewed and measured that complete series another time. All measured good and practically the same but each DAC and each receiver had different electrolytic caps at the DAC/receivers chips supply pins varying from cheap standard to solid aluminium, polymer, Panasonic FC, Black Gate N series and other caps.
Everyone including myself could easily pick out (by ear) both the best sounding ones. I stopped wondering and just choose the caps of the best sounding DACs as recommended parts. Feedback of builders that did not fear experiments confirmed this.
Everyone including myself could easily pick out (by ear) both the best sounding ones. I stopped wondering and just choose the caps of the best sounding DACs as recommended parts. Feedback of builders that did not fear experiments confirmed this.
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Sweet!
So has anyone used this and found anything interesting in regards to DACs?
Looks like in Jean-Paul’s case above this technique ought to work?
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