Nor do you, I might point out. People who aren't delusional or jitter fetishists can read the relevant literature on this from TI, AD, and other sources and come to reasonable conclusions.
What do you think the intrinsic PN of the converter is anyway? How do you even know that your close-in phase noise isn't swamped by the fact that you're feeding it to a real converter? You guys don't even have real measurements other than plugging a clock into an Agilent PNA or whatever you're using and high-fiving yourselves.
What is it they say Joseph? When all you have is a hammer, everything looks like a nail.
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Finally something I agree with, with the observation that the outcome depends on the hypothesis under scrutiny (which also drive the test setup).
The other comment is about who should do such controlled testing and incur the costs; of course, those making the extraordinary claim, they could worst case ask for crowdfunding (and good luck with that).
If you are expecting me or anybody else to prove that something is not audible, then good luck waiting. Last time I've checked, proving a negative is a logical impossibility.
Can't forget the HQPlayer / DSD fetish
. Quite possibly the least productive use of computing power in existence.
No idea, but a III-V 20GHz 28Gbps clock buffer has 0.2pS random jitter and 2 to 6pS deterministic jitter https://www.analog.com/media/en/technical-documentation/data-sheets/hmc850.pdf
According to the criteria exposed here, it would be, subject to listening validation, marginally appropriate for audio with 3 orders of magnitude lower transfer rates.
P.S. Here's a good primer on jitter types and calculations https://teledynelecroy.com/doc/understanding-dj-ddj-pj-jitter-calculations
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This also seems pretty relevant:
https://www.analog.com/media/en/technical-documentation/application-notes/AN-756.pdf
https://www.analog.com/media/en/technical-documentation/application-notes/AN-756.pdf
It's interesting that You say that. I have spent quite some time fiddling about my Mirand dac, based on a 4490.
I have documented with testing the steps of advancement, which mostly consisted of cleaning up crosstalks in the ground plain, by clearly spearating routes for the reference PS etc..
First is jitter spectra before the latest tweaks, second is the same but after tweaks, on the output of the converter. Clock already had been changed, that was one of the first steps.
Each and every intervention around the converter can be seen on the output jitter spectra, in my humble opinion..
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And this was the original format, from where I've started from. I'm sure that all this is totally not audible, I am just "fooling myself" , but that all this is not measurable, on the output of the dac, permit me to refute categorically.
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You fixing pathological issues with your DAC has nothing to do with your fantasyland levels of phase noise and audibility. A bunch of plots without context are not useful.
Where are you controlling this experiment for close-in phase noise differences only?
No one is disputing that you can make measurable improvements to a cheap DAC as far as I’m aware.
Where are you controlling this experiment for close-in phase noise differences only?
No one is disputing that you can make measurable improvements to a cheap DAC as far as I’m aware.
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You do realize that humans invented planes (and other technology) to fly *in*, they didn’t discover that actually we had been flying all along, everyone else just couldn’t realize it (sorta like saying the phase noise is audible y’all are just too poor/ignorant to have systems that could let you hear it)?
Your analogy suggests something much different than jitter fetishism being a worthwhile approach to a “problem” rather than another odd at best fraudulent at worst way to waste money pursuing comfort about the unknown jitter and phase noise y’all imagine hearing. Like Scientology.
Care to just clean up this thread, mods? This is nonsense
If I'm not mistaken they're basically talking of a masking effect where low level signals get masked/buried by the widening of the base by lf phase noise of an adjacent stronger signal. Kind of like the average mp3 is defined.
Now if only we could calculate when this masking effect takes place and becomes detrimental to our perceived SQ.
For instance, is it true that a clock with a lf phase noise of -60dB at 1 Hz makes for a base -60dB wide at 99 and 101 Hz, if the high level signal of e.g. 0dB at 100Hz was taken?
I'd really like to know if that reasoning is correct, because to me this seems like a rather noisy signal.
Nothing at all like the free of rumble, hum and wobblefree digital source it supposedly should be.
And this happens when digitizing as well as when putting back to analog, so we're now hypothetically talking about -54 dB?
I am imagining my speakers being shaken -54dB on the rhythm of every signal it gets.
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The tests I've done are just a valid as yours and prove the exact opposite to what you're saying.
You say you don't have to convince anyone but you're trying awfully hard to do just that. Moreover it looks like you are doing your absolute best to show that your conclusions are correct and need to be taken seriously by everyone. If it didn't matter you wouldn't be posting.
Well, let me know about your tests, setup and XO/OCXO compared.
Maybe you could post a few pictures to better understand what you have compared.
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OT
That is a non sequitur as andrea_mori never stated (afaik), that due to his listening test results, everyone would or must perceive a difference.
Assuming for the moment that both of your results are true, it just means that andrea_mori "hears" a difference while you do not.
That is a non sequitur as andrea_mori never stated (afaik), that due to his listening test results, everyone would or must perceive a difference.
Assuming for the moment that both of your results are true, it just means that andrea_mori "hears" a difference while you do not.
The problem is another: he didn't perceive difference because he never tried.
It's obvious because when I ask to know the conditions of the test he does not answer.
Happy to be proven wrong, I'm still waiting.
What's sad is that you don't even get it.
In one system I've got low phase noise clocks. In another system I went with cheap as chips generic ones. The two systems are completely different. There is no control. There is no scientific method. I made standard DAC jitter measurements that showed the cheap clocks performing significantly worse than the low phase noise clocks.
When listening to the generic clock system it sounded amazing. To the extent where I am happy to conclude that you don't need particularly special clocks for audio.
That is it.
I have measurements of the two systems jitter. Just like you have phase noise measurements of your oscillators.
I have my listening impressions telling me that the cheap oscillators sounded great. You have your listening impressions about low phase noise oscillators.
You probably think that my comparison is flawed to the point of making it pointless. But this is the catch, I think your comparison is just as flawed. That is the point I was trying to make.
If we accept your listening impressions then you also have to accept mine. Neither listening impressions were done with the kind of rigour that science has shown is necessary for this kind of test to mean anything.
In one system I've got low phase noise clocks. In another system I went with cheap as chips generic ones. The two systems are completely different. There is no control. There is no scientific method. I made standard DAC jitter measurements that showed the cheap clocks performing significantly worse than the low phase noise clocks.
When listening to the generic clock system it sounded amazing. To the extent where I am happy to conclude that you don't need particularly special clocks for audio.
That is it.
I have measurements of the two systems jitter. Just like you have phase noise measurements of your oscillators.
I have my listening impressions telling me that the cheap oscillators sounded great. You have your listening impressions about low phase noise oscillators.
You probably think that my comparison is flawed to the point of making it pointless. But this is the catch, I think your comparison is just as flawed. That is the point I was trying to make.
If we accept your listening impressions then you also have to accept mine. Neither listening impressions were done with the kind of rigour that science has shown is necessary for this kind of test to mean anything.
What is really sad is that you continues to not reply about the setup and oscillators used for the comparison.
Of course I accept your measurements and your impressions, but to understand your tests you should specify:
- the audio setup you have used for the comparison
- the oscillators you have compared
- your jitter measurements
Me and the others who made the comparison we have specified the setup, the oscillators and I have posted the measurements.
Otherwise yours it's just words.