[gregorio]

Don't think of it as jitter. It's noise superimposed on the data signal. It is a big problem and will limit your sound quality if you don't deal with it.

It’s the opposite of “a big problem”, in most cases it’s such a minuscule problem that the noise/distortion cannot even be resolved into sound and therefore obviously cannot “limit your sound quality”.

If two audio gears have all the components the same except different quality internal clocks, what is the main metric that measures the quality of sound production? Only the reduced jitter?
I am asking if there's other metric that can reflect the influence of external clock other than the level of added jitter.

Jitter is timing inaccuracies and that’s the only thing that a different clock will affect. A more accurate/better clock does not necessarily reduce jitter though, it’s the processing of the clock signal before it enters the DAC which determines that and with an external clock, it’s the clock recovery circuitry. However, we can also talk in terms of noise/distortion added to the analogue signal upon conversion, as that’s the consequence of jitter, although in pretty much any modern DAC that noise/distortion is vanishingly tiny.

G

 

[MartinWT]

If two audio gears have all the components the same except different quality internal clocks, what is the main metric that measures the quality of sound production? Only the reduced jitter?
I am asking if there's other metric that can reflect the influence of external clock other than the level of added jitter.

Phase Noise is the most important metric, together with short term Allan Variance.

 

[sajunky]

Jitter is timing inaccuracies and that’s the only thing that a different clock will affect. A more accurate/better clock does not necessarily reduce jitter though, it’s the processing of the clock signal before it enters the DAC which determines that and with an external clock, it’s the clock recovery circuitry.

Yip. If inside DAC clock synchronisation do not work as it should, then adding external clock do not bring benefits. Some people report it is a case with Gustard DACs.

External clock brings the best results if source of a synchronous stream is synchronised to the same frequency as a DAC. It makes clock recovery job much simpler, because input data stream never cause buffer under/overruns which is a main reason for using PLL. But PLL do not remove noise in the most important low-frequency area, while adding its own. It is a reason why external clocks are used in a pro-audio.

10MHz clock standard is different to a pro-audio. It presents different challenges. As a new technology, it is frequently not adopted properly. Some companies that offer DAC's and external clocks devices demonstrate that they have problems both with clock generation and clock synchronisation.

 

[gregorio]

Phase Noise is the most important metric, together with short term Allan Variance.

Actually the exact opposite it true, pretty much every other metric is more important than those metrics because even in relatively cheap modern DACs those metrics are dealt with and the artefacts (noise/distortion) are so low in level they cannot even be resolved into sound at any reasonable listening level. Don’t let the facts get in the way of a fun story though! lol

If inside DAC clock synchronisation do not work as it should, then adding external clock do not bring benefits.

Well an external clock would bring benefits in such a scenario but that isn’t applicable because there are no DACs with such poorly performing internal clocks. Even the DACs in cheap consumer gear from before the millennium didn’t have such poor clocks.

It makes clock recovery job much simpler, because input data stream never cause buffer under/overruns which is a main reason for using PLL. But PLL do not remove noise in the most important low-frequency area, while adding its own. It is a reason why external clocks are used in a pro-audio.

If there were buffer under or over runs, data would be lost and you would get dropouts. In almost all scenarios an external clock would either make no difference or actually reduce performance as the clock signal from an external clock has to be processed by the DACs PLL (or similar). So your argument against PLLs is why you should not use an external clock and why external clocks are NOT used in pro-audio! The only exceptions are certain pro-audio applications where the use of an external clock cannot be avoided: In A/V applications (where the audio system has to be ”genlocked” to a video blackburst or tri-level sync clock) or applications where multiple digital units (such as banks of converters, digital mixers, etc.) have to be locked to the same clock signal, although this latter scenario is becoming increasingly uncommon.

G

 

[sajunky]

If there were buffer under or over runs, data would be lost and you would get dropouts.

Actually there are companies not deploying PLL for clock synchronisation. An example is Denafrips. They use very large circular buffer and a clever method to avoid dropouts. They do not share details with you, but such technique has been published in scientific papers. Any developer is aware of this method, nothing new. If you are interested, just search. I am going to stop on it, as it is going off-topic.

In almost all scenarios an external clock would either make no difference or actually reduce performance as the clock signal from an external clock has to be processed by the DACs PLL (or similar). So your argument against PLLs is why you should not use an external clock and why external clocks are NOT used in pro-audio! The only exceptions are certain pro-audio applications...

Thank you for sharing that external clocks have limited use in a studio of your employer.

 

[gregorio]

Actually there are companies not deploying PLL for clock synchronisation.

Yes, there are and have been various topologies and even PLL/clock recovery circuitry varies in performance but the best performing systems result in no better performance than just using the internal clock.

Thank you for sharing that external clocks have limited use in a studio of your employer.

I’m not sure why you’re thanking me for that, because I did not share that external clocks have limited use in “a studio of my employer”, I shared that external clocks have no use in any studio, with the exceptions I detailed. Incidentally, I forgot to mention that 10MHz clocks are not a new technology, I used one in a studio around 20 years ago!

G

 

[sajunky]

I’m not sure why you’re thanking me for that, because I did not share that external clocks have limited use in “a studio of my employer”, I shared that external clocks have no use in any studio, with the exceptions I detailed. Incidentally,

In such case there is no reason to thank you indeed. But I come to a conclusion that your studio do not contract with audiophile grade labels.

I forgot to mention that 10MHz clocks are not a new technology, I used one in a studio around 20 years ago!

Maybe you did, but 10MHz clock is not a mainstream technology in pro-audio. This is a problem I see in your response. In fact it is not a new technology in high-speed communication, GPS applications and very recently in computer datacentres. It is critical for token recognition that a receiver knows exact frequency of a datastream. Consumer audio equipment do not have problems with token recognition, but timing is critical for DA conversion, it is why solutions are similar. Leaking to the consumer audio very recently, so companies need a time to gather experience.

I mentioned in my previous post that in pro-audio there is a different standard, you seem didn't pick it up. No problem, thank you for conversation.

 

[MartinWT]

I mentioned earlier that I had acquired two new Uptone JS-2 power supplies, one for each of my AfterDark clocks. It was easy to listen to just a single change at a time: swapping out a Zero Zone power supply for a JS-2.

This has enabled me to hear just the effect of reducing phase noise in my system by improving the power regulation to the clock and making no other changes. The outcome is a really surprising uplift in sound quality, especially in texture, definition and soundstage. It's hard to believe that changing the power supply to a clock (not even changing the clock itself) can elicit such a dramatic change in the music.

These practical tests have helped me to improve my system; I never would have thought of using choke-regulated PSUs for a clock application. Hearing is believing.

 

[Psilonaught]

@MartinWT unfortunately the Cisco AOC assembly isn't compatible with my Netgear Nighthawk x10 which is a bummer.

Their list of tested transceivers is here

https://kb.netgear.com/31408/What-S...hthawk-Pro-Gaming-XR700-routers?article=31408

Just wondering if you think it would be worth me trying a FTLF1318P3BTL??

 

[MartinWT]

Just wondering if you think it would be worth me trying a FTLF1318P3BTL??

That's a shame. I couldn't comment, I'm afraid - they all sound quite different and I haven't tested that Finisar.

 

[Presence]

I recall the "latest sensation" when modernly packaged Single-Ended Triodes became "the new" audiophile market focus back in the early 90s and Stereophile contrasted the debate between solid state vs. single-ended zero feedback designs. Then Cary introduced a feedback dial from 0-10% so listeners could both correlate the measurements with feedback and hear the effects.

I was contemplating trade offs in my choice of a NOS DAC because I wanted the best time-domain performance as evidenced in its reproduction of an impulse response compared to other filtered approaches that introduce ringing. I don't have a right answer but like Cary introducing a dial with feedback control, it'd find it usefully revealing to be able to have a fantasy dial to introduce ringing and jitter on MY platform to have some experience of their tradeoffs.

In the meantime, I don't have an Audio Precision to make measured inferences but I do trust my ears to tell when my mods are headed in the right direction or not...
If this is "wrong" then I'll take more WRONG please. Austin Powers filling out job application - Sex? "Yes please"

With what's going on in this thread it makes it difficult to want to inquire or share experiments and experiences for fear of being invalided/shut down in the name of tribalism.
Both sides have deep experiences to share but when it becomes adversarial it shuts down the opportunity for the rest of us to learn - which for me, is what it's all about.
A thread Reset Button would be pretty cool right about now...

I love imaging and holography as I find it suspends my mind's evaluation of the music and allows me to become immersed in it. I have my own inventory of smeared music passages [both time and frequency-based] that annoy the crap out of me that I always go back to after my latest equipment mod. For example, a clarinet or violin ascending in scale where certain notes sound bottle-necked as the harmonics sound constrained and don't bloom like the rest of the range. It's no wonder until recently I couldn't stand listening to classical music [I still largely can't ]
Check out Sarah Chang track 2 "Adiagio"
She's awesome! Even without distortion and feedback she and Sophie Mutter I believe still smoke most shredding metal guitarists!

There is lack of consensus in many areas in audio - John Atkinson has commented after a DAC review with poor measurement performance, " It's hard to know whether it sounded as good as it did because of the measurements or in spite of them".
In addition to my NOS DAC, I chose loudspeakers that are phase coherent and reproduce an "accurate" impulse response as yet another means to best reproduce imaging and holography.
And yet there are differing audiophile camps that disagree over this. I recall Richard Vandersteen and Gayle Martin [Martin/Logan] arguing over importance of impulse response of a loudspeaker at a Stereophile show "Meet The Designer" presentation.

While I haven't seen that anyone is particularly interested in this and perhaps this should go on the Audio GD product thread instead, I inquired a while back about the direct earth grounding of the BNC barrel on my Audio GD R8 DAC and being connected to a transformer-coupled Mutec Ref10 SE120, whether the coax cable [75ohm Harmonic Tech Silver] would act as an antennae. One reader I believe commented that it would.
So I removed the terminating 75ohm SMD resistor and added a 75ohm balun [isolation transformer]
https://www.digikey.com/en/products...13927615?so=84687585&content=productdetail_US
inside the AGD DAC and noticed the spacial/holographic presentation had expanded and the frequency bottleneck of inventoried passages [that annoy the crap out of me] were very significantly reduced. The frequency presentation initially sounded much worse until about 100 hours or so of settling in.

I love to experience separation and dimensionality listening to rock/studio recordings with out-of-phase content.

- When a guitar doubles over the bass part and out of the silence I can differentiate the two.
Especially if the guitar is out of phase and adding low-level texture. Otherwise the two parts fuse together to sound like one event and the space/separation from the out-of-phase guitar is lost.
- ZZ Top does a great job with out-of-phase effects that nicely fill in the sound stage - sometimes from zero to 180 degrees where the guitar originates at one area of the soundstage and decays in another - often times outside of the speakers.
- Yes and The Who also have so much going on that is out of phase. It's nearly always from a zero - 180 degree soundstage [as are many other rock studio mixes]
It's nice to be inserted into a 180 degree hemisphere where each instrument and voice has its own 3-D space that overlaps the 3-D space of other instruments/voices.
Also, when out of phase content is reproduced more accurately, it takes on a preciseness with more weight to the image outside the speakers vs the previous level of vagueness experienced before improving system resolution
- When bass is more controlled, it seems to reach deeper and absence of bloat exposes timbre of the bass guitar or standup.
The once bloated sub-synth effect [?] on the voice from the track "Three Wishes" on Roger Waters "Amused To Death" really tightened up.
I had this passage in my "annoyance inventory" for years to only recently learn that it was largely due to my front end.
I could keep going but I'll wrap it up.

Let's keep learning from each other. You guys all have deep experiences that should be voiced but not ongoingly and territorialy fought over...
I hope this makes sense. Thanks for listening.

Rich

 

[MartinWT]

Hi Rich

Stick to your beliefs and trust what you hear, you seem to be saying that and it's all you'll need. There is only tribalism from entrenched views. Ask questions, try things out and form your own opinions.

I'm listening to the Sarah Chang and it's a reasonable recording for a Warner but the mix sounds unbalanced. Kurt Masur* I have a lot of time for. Chang plays well enough and the violin is not full-on as in some presentations, yet it gets harsh in the crescendi. The orchestra are a little murky when things get busy, too.

*his masterful conducting of Jessye Norman and the Gewandhausorchester performing Strauss' Four Last Songs is some of the best music making I have ever heard.

EDIT: that synth voice on Three Wishes is very tight and grunty on my system.

 

[Psilonaught]

Sorry i have more SFP questions... I'm trying to find this famous Corning "gold" cable.

Am I right in thinking that the one referenced here https://www.adark.co/products/copy-...ayx-constellation-sfp-module-for-audiophile-1

Is Corning SMF Ultra Fibre Optic Patch Cable 2 x 2.0 mm Singlemode Duplex LC ??

 

[duffer5]

Sorry i have more SFP questions... I'm trying to find this famous Corning "gold" cable.

Am I right in thinking that the one referenced here https://www.adark.co/products/copy-...ayx-constellation-sfp-module-for-audiophile-1

Is Corning SMF Ultra Fibre Optic Patch Cable 2 x 2.0 mm Singlemode Duplex LC ??

https://www.eaccu-tech.com/patch-cords/fiber/040402r5120002m-corning/

 

[Psilonaught]

https://www.eaccu-tech.com/patch-cords/fiber/040402r5120002m-corning/

Thanks