[audioengr]

So, what might this mean for the average audiophile like me? Let’s take just one example. My very best digital recording is a Mercury SACD of Rachmaninoff’s 3rd Piano Concerto played by Byron Janis. The original recording was made in 1960.
 
But I also have the same recording on vinyl. I had a group listening session a couple of weeks ago in which I played both versions. The result: everyone preferred the vinyl version.

Means nothing.  The is no doubt in my mind that you have very high jitter in your digital system.  Bring this down and reduce the distortion in your DAC and you will rival or exceed the vinyl sound quality.

Want to hear REALLY low jitter?  Try a Sonos followed by a Synchro-Mesh reclocker into a Metrum Pavane DAC (no reclocking).

Steve N.

[HAL]

This is a decent oscillator at 45 and 49MHz, but not at 24 or 22MHz.

Try this one instead:

https://www.mouser.com/datasheet/2/94/CCHD-575-18036.pdf

Steve N.

Looking at the two datasheets the noise floor for the first unit is 7dB lower noise at 10Hz than the second datasheet for the 22MHz and 24MHz parts.  Why would it be better?

[art]

This is a decent oscillator at 45 and 49MHz, but not at 24 or 22MHz.

Sort of right.....................

Those parts should NOT have the same phase noise numbers. There should be a 6 dB difference, between the 22/24 ones and the 45/49 ones.

Try this one instead:

https://www.mouser.com/datasheet/2/94/CCHD-575-18036.pdf

Steve N.

Uh, no thanks!

Only if you worship at the altar of low noise floor. Which most of the industry does. Which is also why they are wrong.

[art]

Looking at the two datasheets the noise floor for the first unit is 7dB lower noise at 10Hz than the second datasheet for the 22MHz and 24MHz parts.  Why would it be better?

Because the industry is convinced they are experts, and noise floor is the most important spec.

(IOW, see above post.)

[audioengr]

Looking at the two datasheets the noise floor for the first unit is 7dB lower noise at 10Hz than the second datasheet for the 22MHz and 24MHz parts.  Why would it be better?

At 10Hz, the 575 is -101dB, the 957 is -98 dB, both at 24.576MHz.  The 575 is better at this frequency, 3dB better.

It's the phase jitter that is highest that will be audible, not that at 100KHz which is the "noise floor".  Nobody can hear -165dB or -170dB.

Steve N.

[wushuliu]

Nothing magic about it.

Mouser...................Digikey....... ........others...................

http://www.crystek.com/crystal/spec-sheets/clock/CCHD-957.pdf

Well, well, well. That just happens to be the clock I bought a little while ago for some cheap dac diy'ing (along w/ your Newava recommendations). I was pleasantly surprised by what I heard. I was skeptical I'd hear much daylight between it and the clock it replaced - the above-mentioned Crystek 575 (and before that, a Fox Xpresso). But the 957 sounds noticeably better to me.

[art]

It's the phase jitter that is highest that will be audible,

?????

Oh, really.........................

not that at 100KHz which is the "noise floor".  Nobody can hear -165dB or -170dB.

Steve N.

Then why do guys like you rely so heavily on measurements that are really nothing but the noise floor? (That is what your fancy Tek 'scope does, whether you want to admit it or not.)

What you fail to realize is there are other metrics, that determine a clock's suitability, for use in a digital audio system.  The phase noise is just part of it, and is the easiest to comprehend. (The folks that build these parts know all of this. They also know what the "magic numbers" are, for all of those other bizarre and obtuse metrics. Why do you think they are willing to work with such a PITA like me? Because I know this stuff, and have the understanding which ones are important and why they are important. And more significantly at what level they are important.)

But you guys feel free to brag about how many fSec of jitter that your stuff has, based on the noise floor specs.

[audioengr]

?????

Oh, really.........................


Then why do guys like you rely so heavily on measurements that are really nothing but the noise floor? (That is what your fancy Tek 'scope does, whether you want to admit it or not.)

What you fail to realize is there are other metrics, that determine a clock's suitability, for use in a digital audio system.  The phase noise is just part of it, and is the easiest to comprehend. (The folks that build these parts know all of this. They also know what the "magic numbers" are, for all of those other bizarre and obtuse metrics. Why do you think they are willing to work with such a PITA like me? Because I know this stuff, and have the understanding which ones are important and why they are important. And more significantly at what level they are important.)

But you guys feel free to brag about how many fSec of jitter that your stuff has, based on the noise floor specs.

The period jitter distribution is not the noise floor.  All of the metrics, including phase noise plots, period jitter distribution plots, period jitter spectrum plot and listening tests are needed to fully characterize the jitter.

Steve N.

[HAL]

Did not have to remove the top.  Plenty of pictures of it on the web.  Could not find the part numbers DFAS13-LH with the clock frequencies, but it is from 2011.  Any idea about them would be interesting.

The hiFace Evo clock unit pc board from the search:

[art]

The period jitter distribution is not the noise floor.  All of the metrics, including phase noise plots, period jitter distribution plots, period jitter spectrum plot and listening tests are needed to fully characterize the jitter.

Steve N.

That, on its own, is debatable, but is of ZERO value, when discussing clock jitter. Which is what this is about.

But, fine, you believe whatever you want to believe. I have the feeling any further discourse with you is an exercise in futility.

For everyone else.....................

If one of you guys swaps out the bog standard clock, with one that is "ok" (by the metrics ne'er-do-wells like us use), and it sounds "day and night different", what has changed? Has any of the stuff someone here likes to ramble about (because that is what they have to measure "jitter") changed? NO! The only thing that has changed is the clock, and none of those metrics are applicable to quantifying any clock.

But, what do I know..............................

And for the record......................

Yes, we have expensive gear that measures all of that other crap. I can say with 100% certainty is useless, when it comes to clock jitter. In fact, one of the best clocks (in our shop) measures like doo-doo, when those metrics are used.

Why?

Because it gives a "double-hump" histogram. IOW, it is the kind of result one would see if there is "deterministic" or "correlated" jitter present. (A good example of this would be mains-related crud getting into the clock supply, and mucking things up.)

In this case, it is due to an odd-looking, slightly asymmetrical waveform, that is created when you take a 5 MHz "rock", build an oscillator with it, and run it through a Class C amp to make a 10 MHz oscillator. (You can see what its phase noise looks like somewhere in this thread.) (Should not be too hard to figure out which one it is, since you already know it is a 10 MHz one. The last hint is how good its phase noise plot is.)

[art]

Oh, so it is "those guys". Yes, those guys, from the land of my ancestors.

OK, joke time.

A good buddy is an Alfa Romeo fanatic. (And not of a heritage from that place.)

"Know what the best thing about an Alfa is?"
"No. What?"
"Designed by the Italians! Know what the worst thing about an Alfa is?"
"No, please tell me."
"Built by the Italians!"
"Well, duh!"
"I see that you know Luigi and his cousins."
"Yeah, because they would be my cousins, if they were not in Milano."

OK, no more jokes....................

Spec sheet:

https://lnx.m2tech.biz/wp-content/uploads/2017/06/Evo-Clock-Two-User-Manual-PrA.pdf

Most important part:

Phase noise:
-98dBc/Hz (@ 10Hz)
-131dBc/Hz (@ 100Hz)
-144dBc/Hz (@ 1kHz)
-154dBc/Hz (@10kHz)

(Looks like a 24.xxx MHz clock.)

IOW, about the same as that $20-30 part previously mentioned.

Since they no longer make them, you can make something that works just as well for a lot less than what they sold theirs for. Better than what a lot of you presently have. Still leaves a lot to be desired.

(No, we have no plans to make a similar product. Folks in the Pro Audio world have approached us about this. When you talk to the places they buy their stuff from, and ask them what kind of demand they see, for this type of product................................ ...)

(Like I said, we have no such plans!)

[HAL]

art,
Thanks for the feedback.

I have one and it has both the 22.5792MHz and 24.576MHz clocks in it with the switch between the two.

Looks like no real upgrade going from what is already installed and something 8 years newer from your observation in the thread.

[art]

Yep, not much sense in mucking it up.

[audioengr]

Because it gives a "double-hump" histogram. IOW, it is the kind of result one would see if there is "deterministic" or "correlated" jitter present. (A good example of this would be mains-related crud getting into the clock supply, and mucking things up.)

Not always.  Here is my Synchro-Mesh reclocker output at the end of a 4-foot coax cable:



The double-hump can be caused by impedance mismatch as well.

Steve N.

[tubesguy2]

I posted this yesterday on the ar-t forum, but have a few more thoughts:

"I'm still listening to music, rather than devoting much time to writing, but I'd be remiss if I let too much time go by before saying that the new Legato arrived on Friday, and is one of the best audio devices that I've ever had a chance to evaluate. From the very first track, it has impressed with an organic, but crystal-clear rendition of the textures, timing and timbres of everything I chose, whether "audiophile" or just plain ol' damn good music.

I had thought that I was one of those guys who had to upsample everything to DSD1024 to, you know, make it sound extremely hi-res, but please trust me on this: Properly reproduced (and this isn't, I'm sure, limited just to a good clock) 44.1 recordings are incredibly satisfying. More to come, but if you have a chance to audition one of these, do so."

A couple of things that I've been asked:

"Wait, limited to 44.1? I've got all kinds of hi-res recordings, both PCM and DSD. Why would I want to retreat to mere CD resolution?" Well, as Pat and others have pointed out, the 22 and 24mhz clocks have better phase noise performance than their 44 and 49mhz counterparts, regardless of manufacturer or price point.  And I'm now a believer that ar-t's testing and sorting abilities can produce superior digital reproduction, at least compared to anything that I've had in the past.

You can, using the software that you probably are already using (I use Daphile, a free Linux-based streaming system), convert all of your hi-res recordings on the fly to 44.1 output, and to these ears, 44.1 playback done extremely well is superior to any of the hi-res formats. In my house, and on my system.

"Yeah, but SPDIF? Hadn't we long ago abandoned that primitive tech for fancy USB to I2S gizmos (and, of course, some necessary "purifiers")?" Yes, but unless you're doing that process inside the DAC, there can be problems with things like the length of the I2S wiring that are significant, and you're still at the mercy of that first piece of the puzzle, the clock, or clocks. I've seen (and used, I'll admit) some boards that eschew the old-fashioned low speed clocks and push it to 90 and 98. It's true that you are at the mercy of the design of the receiving circuit in the DAC or other device, but Pat has spent many years perfecting the design of the transmitting side and associated hardware. (Use a long cable.  )

In short, the Legato is a great audio device, one of the best that I've spent my own hard-earned dough on, and, in the specific context of this thread, it appears to be the answer to the question of how significant clock jitter is in the whole process.

[wushuliu]

Just want to say with great sadness that the OP 'art', Patrick DiGiacomo aka Jocko Homo (on diyaudio and diyhifi.org) passed away a month ago...