Audio-GD DI-20
Aug 7, 2022 at 3:15 PM Post #3,828 of 4,373

DACLadder

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Aug 7, 2022 at 3:49 PM Post #3,829 of 4,373

dougms3

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Aug 7, 2022 at 4:09 PM Post #3,830 of 4,373

rsbrsvp

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Phase noise is NOT the only number that matters in a external clock. Thermal temperature and other numbers also effect results. Many OXCO manufacturers actually believe thermal temperature is more important than phase noise including Morion.

Innuos uses a OXCO with -85dcb noise in their OXCO for their phoenixusb. Pretty bad hu? Well- I saw two comparisons comparing the phoenixusb to the STOM tx-usb ultra reclocker using a Paul Hynes SR7 power supply and Mutec Ref10 clock with -115dcb phase noise and both said the phoenixusb was better (and much much cheaper). I had some emails with innuos and they said they tried many many OXCO's with their phoenixusb and many had much lower phase noise than the one they chose, but sounded worse. We oversimplify when we stress phase noise as being the only important number in an external clock.....

In addition- all 10mhz external clocks increase jitter (timing errors) even though they reduce phase noise. Look it up on google.....
 
Aug 7, 2022 at 5:11 PM Post #3,831 of 4,373

sajunky

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Phase noise is NOT the only number that matters in a external clock. Thermal temperature and other numbers also effect results. Many OXCO manufacturers actually believe thermal temperature is more important than phase noise including Morion.
What is thermal temperature affect other than a long term nominal frequency? Is this important to us and how? What are these other parameters?
In addition- all 10mhz external clocks increase jitter (timing errors) even though they reduce phase noise. Look it up on google.....
Yes, synchronisation errors are prevented (therefore do not contribute to the phase noise increase) if two devices are referenced by the same clock. I think this is what you have heard. Whether external clocks increase jitter is a matter of a type of internal clocks and end result cannot be predicted easily. So called and very popular ultra-low phase (fem-to-second) oscilators use digital PLL internally tuned to a fixed frequency. Clock digital synthesisers for 10MHz external clock use a similar technology and in both cases quality depends on the source clock. It means, external clock wins, but there are losses on connections. In other words, it may or may not...

One thing you need to remember. Phase noise is the same as jitter. Calculated differently, but the same. And which term is used, it depends on the application. External clocks have lower phase noise in a low frequency spectrum, while PLL generated clocks excel in higher frequecies, above middle audio spectrum range, but filtration is less effective for frequencies below 1kHz. For audio purpose this is the most important range.
 
Aug 7, 2022 at 5:27 PM Post #3,832 of 4,373

FredA

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What is thermal temperature affect other than a long term nominal frequency? Is this important to us and how? What are these other parameters?

Yes, synchronisation errors are prevented (therefore do not contribute to the phase noise increase) if two devices are referenced by the same clock. I think this is what you have heard. Whether external clocks increase jitter is a matter of a type of internal clocks and end result cannot be predicted easily. So called and very popular ultra-low phase (fem-to-second) oscilators use digital PLL internally tuned to a fixed frequency. Clock digital synthesisers for 10MHz external clock use a similar technology and in both cases quality depends on the source clock. It means, external clock wins, but there are losses on connections. In other words, it may or may not...

One thing you need to remember. Phase noise is the same as jitter. Calculated differently, but the same. And which term is used, it depends on the application. External clocks have lower phase noise in a low frequency spectrum, while PLL generated clocks excel in higher frequecies, above middle audio spectrum range, but filtration is less effective for frequencies below 1kHz. For audio purpose this is the most important range.
Yeah. Something many don't get get. Phase noise and jitter are different ways of looking at the same thing. Jitter is an average figure over the audio band giving the average timing error in seconds. Phase noise is more detailed, it give the specific timing error as a function of frequency. A phase error can easily be tranlated into a number in seconds, for those wondering.
 
Aug 7, 2022 at 5:29 PM Post #3,833 of 4,373

rsbrsvp

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What is thermal temperature affect other than a long term nominal frequency? Is this important to us and how? What are these other parameters?

Yes, synchronisation errors are prevented (therefore do not contribute to the phase noise increase) if two devices are referenced by the same clock. I think this is what you have heard. Whether external clocks increase jitter is a matter of a type of internal clocks and end result cannot be predicted easily. So called and very popular ultra-low phase (fem-to-second) oscilators use digital PLL internally tuned to a fixed frequency. Clock digital synthesisers for 10MHz external clock use a similar technology and in both cases quality depends on the source clock. It means, external clock wins, but there are losses on connections. In other words, it may or may not...

One thing you need to remember. Phase noise is the same as jitter. Calculated differently, but the same. And which term is used, it depends on the application. External clocks have lower phase noise in a low frequency spectrum, while PLL generated clocks excel in higher frequecies, above middle audio spectrum range, but filtration is less effective for frequencies below 1kHz. For audio purpose this is the most important range.
I am not very technically adept but if you look at the Morion site- they say clearly that thermal temperature is the single most important factor in OXCO clock performance. Why?- I have no idea. Stability, and other measurements which I don't understand also effect.

In addition- many technically minded people have told me that these -121dcb clocks will NOT get anywhere near that number in a non controlled home environment. The manufacturer of the Hibiki 10mhz clock, and innuos both told me this as well.

Again- the Phoenixusb is perhaps the most highly respected usb reclocker made. It uses a -85dcb OXCO. It beat out in several comparisons the SOTM usb reclocker using Ref10 (-115dcb) clocking and paul Hynes PS in several reviews. Check Auudiobacon and Audiophilelifestyle forum for several of these comparisons...

From my personal experience, I recently owned two etherregens for which I had Ref10 -120SE clock hooked up to both of these switches... I compared it to the innuos phoenixnet with -85dcb clock and it was about a tie to my ears. I see from this that the phase noise number is not everything.... So many other factors I do not understand...
 
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Aug 7, 2022 at 5:36 PM Post #3,834 of 4,373

rsbrsvp

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If phase noise and jitter are the same thing- than external clocks harm jitter- and do not improve it..

Google quotes:
1. 10MHz master clocks use rate multipliers to convert to digital audio rates, which generate more jitter and tend to have a dirtier spectrum.31 Oct 2020
2. Although external clocks do increase jitter, it's a FACT there is a widely reporting increase in SQ.
 
Aug 7, 2022 at 5:40 PM Post #3,835 of 4,373

rsbrsvp

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Check out this article: https://www.soundonsound.com/techniques/does-your-studio-need-digital-master-clock

Overall, it should be clear from these tests that employing an external master clock cannot and will not improve the sound quality of a digital audio system. It might change it, and subjectively that change might be preferred, but it won't change things for the better in any technical sense. A‑D conversion performance will not improve: the best that can be hoped for is that the A‑D conversion won't become significantly degraded. In most cases, the technical performance will actually become worse, albeit only marginally so.
 
Aug 7, 2022 at 5:42 PM Post #3,836 of 4,373

rsbrsvp

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So- for a fellow who is not technically capable, I'm really getting in over my head. My intention was just to make it clear that it does not seem clear at all that external clocks help- and seemingly- unless I am really misunderstanding these articles- they technically make things worse...

You technically minded headfiers are welcome to correct me and put me in my place if need be.... i welcome your input
 
Aug 7, 2022 at 5:43 PM Post #3,837 of 4,373

FredA

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Check out this article: https://www.soundonsound.com/techniques/does-your-studio-need-digital-master-clock

Overall, it should be clear from these tests that employing an external master clock cannot and will not improve the sound quality of a digital audio system. It might change it, and subjectively that change might be preferred, but it won't change things for the better in any technical sense. A‑D conversion performance will not improve: the best that can be hoped for is that the A‑D conversion won't become significantly degraded. In most cases, the technical performance will actually become worse, albeit only marginally so.
It is not my experience. External clocks with Audio-gd improve staging and bass quality.
 
Aug 7, 2022 at 5:49 PM Post #3,840 of 4,373

FredA

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Check out this article: https://www.soundonsound.com/techniques/does-your-studio-need-digital-master-clock

Overall, it should be clear from these tests that employing an external master clock cannot and will not improve the sound quality of a digital audio system. It might change it, and subjectively that change might be preferred, but it won't change things for the better in any technical sense. A‑D conversion performance will not improve: the best that can be hoped for is that the A‑D conversion won't become significantly degraded. In most cases, the technical performance will actually become worse, albeit only marginally so.
This article misses a very important point: phase noise under 20hz is detrimental to sound quality and no internal clock i know of can come close to an ext master clock with this regard. So using the internal clock, you are stuck with this low freq phase noise.
 

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