Jocko Homo Audio

Audio Topics => Digital Audio Stuff => Topic started by: Gen. Dreedle on December 30, 2012, 10:08:39 AM

Title: They're talking about jitter......................
Post by: Gen. Dreedle on December 30, 2012, 10:08:39 AM
Quote
Now I don't know the integration time of my AP. if you look at the phase noise ratings of crystal oscillators you will see the noise goes up as the frequency decreases. This 1/f effect may very well translate into enough jitter to cause missed bits.

Uh................well................that 1/f stuff does something more subtle. If you are into "imaging" and "three dimensionality", you must have low 1/f jitter.

I alluded to this over at Greaser's Palace: the gang I work with has come to the conclusion that Allan Deviation is the best way to characterize clocks. Since effective phase noise will go up 6 dB, with every doubling of frequency, you can't always say "x dBc @ 1 Hz" is the magic number. But, with Allan Deviation.............it will stay the same, at any frequency. And the magic number occurs at 0.1 sec. At least that is the conclusion of the cabal in Texas.

Now, what that magic number is...................ain't sayin'! Gotta hold something back in case any consulting work comes along. But, so far, it has held up to scrutiny.
Title: Re: They're talking about jitter......................
Post by: seagreen on December 30, 2012, 11:23:48 AM
Well... Yeah!

It's funny how what some people consider better resistors have lower 1/f sidebands than other resistors.

Or, how PM-AM conversion manifests itself at about the same level.

Or, how way above 20 KHz stuff can migrate in and cause the same sorts of effects.

Or, oh forget it!   Lunatic ravings of a crazy person.   :-X   At least I know that nobody would hire me for consulting work.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on December 30, 2012, 09:20:42 PM
Quote
On 125th AES Show (2008) Keith Johnson presented a master class Sonic Methodology and Mythology
Unfortunately I couldn't find any recorded information from this master class on the Net. The letter from Keith is cited, where he explained what was presented.
I attended this master class. Essentially he constructed low-bandwidth PLL system and analyzed the error signal (listened). Different optical/copper digital cable in the system revealed in different PLL error signal. Different power cords and their placement also gave different signature in PLL error.
More about Keith can be found here


Lemme guess................more "anecdotal evidence". I've spent 20 years trying to convince people to listen to the PLL error signal. I didn't need a TDR to know that cables made a difference. (Still more anecdotal evidence.)
Title: Re: They're talking about jitter......................
Post by: seagreen on December 31, 2012, 06:30:15 AM
My theory is that the high sunspot count is affecting people's brain activity.
Title: Re: They're talking about jitter......................
Post by: MystereoN on January 14, 2013, 02:32:19 AM
Since we all know our General adores crystals: http://archive.org/details/6101_Crystals_Go_to_War_01_20_16_21 (http://archive.org/details/6101_Crystals_Go_to_War_01_20_16_21)

Fascinating historical stuff
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on January 16, 2013, 06:05:53 AM
Is it really 41 minutes long?
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on July 22, 2013, 08:21:27 PM
Link to another link:

http://www.diyaudio.com/forums/analog-line-level/146693-john-curls-blowtorch-preamplifier-part-ii-4188.html#post3570395 (http://www.diyaudio.com/forums/analog-line-level/146693-john-curls-blowtorch-preamplifier-part-ii-4188.html#post3570395)

And the usual kvetching.

Actually, to be fair................not sure if the fallout is the fact that some guy has also figured out that sub- 1 Hz jitter is important, or that some putz is selling a $15k clock. Or that the clock probably sucks, because it is just another rubidium standard. Or all 3. (Who knows? Probably all 3, with that bunch.)
Title: Re: They're talking about jitter......................
Post by: seagreen on July 23, 2013, 03:03:45 AM
I believe Terra Firma is a SAW based oscillator.

In any case, clocks are only effects boxes.  I know it's true, because I read it on the Internet.

However, I confess that I can't get my arms around these:

http://www.diyaudio.com/forums/analog-line-level/146693-john-curls-blowtorch-preamplifier-part-ii-4188.html#post3570355 (http://www.diyaudio.com/forums/analog-line-level/146693-john-curls-blowtorch-preamplifier-part-ii-4188.html#post3570355)

http://www.diyaudio.com/forums/analog-line-level/146693-john-curls-blowtorch-preamplifier-part-ii-4188.html#post3570652 (http://www.diyaudio.com/forums/analog-line-level/146693-john-curls-blowtorch-preamplifier-part-ii-4188.html#post3570652)

Where and how was it determined that DBT and the simple suite of audio tests commonly used are either adequate or entirely accurate for specifying performance of a system used to stimulate a person's senses?  Not "accepted" but determined.

Me thinks that reductionism can only be taken so far, especially when all interactive parameters and dependencies aren't well defined, understood, or worse, just plain ignored.  I guess systems thinking might upset their dogma...

Waddya do?

Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on July 23, 2013, 06:54:24 AM
It might be SAW based. Hard to tell, since he spends too much time talking about some POC Harley discovered.


Ok the ironic part...........SAWs have a lower noise floor, than multiplier-based clocks. But, not so great, when it comes to 1/f.

But, they may have changed, since I looked at them, a while back.

As for those other 2 guys.......................one contradicts himself, although he would argue that we don't understand what he is saying. (Yeah, think so!?) The other one............ok, I prefer A over B, but I can only say I prefer it, and not that B sucks.

So, I can do a DBT, with one amp in clipping, for most of the time, but I can not say it is worse than the one that sounds good. Go figure. (I'm sure the same rebuttal will apply.)

At the end of the day, no one really cares why they like what they like, as long as they are happy with what they like. But, no.............unless you like it for the right reason(s), then...................hey, wait.............that starts to sound like fascism.

Oh, I understand: wine notzy-cum-audio notzy! It all makes sense now............

"Comply, or else."

Or else what?

"We make you listen to Bose."
Title: Re: They're talking about jitter......................
Post by: seagreen on July 23, 2013, 10:31:27 AM
SAWS'r'Us:

http://www.diyaudio.com/forums/digital-source/222596-oppo-s-bdp105-discussions-upgrading-mods.html (http://www.diyaudio.com/forums/digital-source/222596-oppo-s-bdp105-discussions-upgrading-mods.html)

I hear you on the rest...

Just this very morning on my joyful commute - now 25 miles longer... - I was listening to some PhD types discussing multi-tasking.  PhDs know everything, you know.  Anyway, they were saying that the latest serious studies show that the human brain does not really multi-task very well.  At all.  No need for me to go over the rest. 

But, I, already multi-tasking myself by driving and listening, had a flash.  Or a stroke.  Not sure which.

If you are listening and trying at the same time to do whatever else you do for a DBT, subtle things would become ignored in the primary focus.  At least according to these guys.

Great, eh?

They're probably boobs, though.

Title: Re: They're talking about jitter......................
Post by: Kryten on July 26, 2013, 11:26:03 PM
(http://www.customanalogue.com/images/TFL_1000W_border.jpg)
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on November 30, 2013, 11:47:32 PM
Well, not about jitter, per se, but..............it is headed in that direction.........

OK, some poor sod, over on The Pub, wants to change the clock in his digital whatever disc playin' thingamajig.  Problem is................

It has 3 clocks, and he does not know which one to change out!

OK, friendly advice, that you will not find helpful, friendly, or even welcome (but we can do whatever we want here), but.............

If you don't know which one to change, then why are you wanting to change it?

Translation: Ok, you don't know which one it is, but you are certain that you will replace it with something better.

Right............................

(And since it probably has one 27 MHz "master clock", it isn't going to matter!)

Let's see how long it takes the brain trust of that place to point out that simple fact.

Oy vey.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on May 13, 2015, 10:47:24 PM
Well, now they are going at it in the Blowtorch thread. (I don't read that crap: someone called to tell me.)

Ah...............the usual experts and over-paid consultants, showing how ignorant they truly are.

Good luck trying to measure clock jitter, at the output of a DAC. Oh, it will measure jitter. Just not the clock jitter. Just because they are under the misapprehension they can does not make it so.

Better luck measuring it with an FM tuner! (Hint: if you can hear it on an FM tuner, you have problems.)

Back to their regularly scheduled nonsense.
Title: Re: They're talking about jitter......................
Post by: MystereoN on May 16, 2015, 10:25:40 AM
Yes, a lot of entertainment and laughing

BTW: anyone knows what frequency should I dial on my FM tuner to hear jitter?

 ;D
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on June 02, 2015, 12:20:36 AM
Andrea Doria thinks you can simulate an oscillator, and it will tell you how well it is going to work.

I see someone told him about the "B" mode, that SC-cut crystals have. I would have let him learn it the hard way.

Not that it will make much difference, in the long run.

Someone needs to get hold of one of his standard offerings, so we can measure it and see how bad it is.

I know................I'm rotten!
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on August 16, 2015, 10:34:43 AM
Someone just told me about this one, over at that other place:

Quote
Besides Gerhard's warning about the difficulty to suppress the so-called "B"-mode, which is just 9% to 10% above the desired "C"-mode, there my be an issue if you operate an SC crystal without oven at room temperature. Because the frequency vs. temperature characteristic has a rather deep slope around RT, any minor temperature fluctuation will immediately translate into close-to-carrier phase noise and jitter. Thus the inherent advantage of an SC cut may be cancelled by this effect.

Right about the "B" mode.

Wrong about what happens at RT, wrt phase noise.

Yes, the frequency will change, if you look at it. It doesn't mess up the close-in phase noise. Somewhere I have some plots that prove this, but what do I know? I'm just some redneck in Texas.

There are some other things I can not  talk about. My associates are working on some things we are constrained by NDAs.

Maybe soon..............
Title: Re: They're talking about jitter......................
Post by: MystereoN on August 16, 2015, 02:54:56 PM
Keep up the good work, we are awaiting good news  :)
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on August 19, 2015, 09:26:51 AM
Word is some important folks are going to be here, on Thursday, to meet with the Ace Face.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on December 28, 2015, 09:24:33 PM
I see the usual "experts" are re-hashing the same ol' same ol', acting like they are at the cutting edge.

Hey, experts, I tried that 15 years ago, and it is NOT good enough.

But, it is a free country, and you are free to waste your own money and time, as you see fit. Just don't try to con us that you are on top of things.

And, yes, you really do need to measure below 1 Hz. And, yes, Allan Deviation would show the same stuff, more or less, but that doesn't mean you understand any of it.

Clearly, you do not.

Give up.
Title: Re: They're talking about jitter......................
Post by: MystereoN on December 30, 2015, 11:55:04 AM
DiyA thread from "testa dura" about master clock?
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on January 08, 2016, 12:42:56 PM
Si.
Title: Re: They're talking about jitter......................
Post by: MystereoN on April 23, 2016, 03:00:32 AM
I like older Dutch gentleman very much  :)
Title: Re: They're talking about jitter......................
Post by: MystereoN on July 14, 2016, 02:38:38 PM
Nothing new on the DiyA, "experts" are still re-hashing the same ol' same ol' and presenting Epay POC as SOTA no-jitter design  :-\
LINK (http://www.diyaudio.com/forums/equipment-tools/292222-info-ultraanalog-jitter-analyzer-2.html)
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on August 10, 2016, 06:47:08 AM
Do me a favor, and see if you can get John W to contact me. I have his Skype number.............well, it was................it no longer works.

Anyway............they are talking about me, again!

Quote
Someone very known in the diy audio circle got -122dBc at 10 Hz from the carrier with a simple unbuffered '04 Pierce oscillator. He got this result using a 0.35 USD crystal strongly selected from a bag of them. Most of them were discarded because they performed very bad.

But they still won't listen. IDIOTS!

(You notice he did not specify the oscillation frequency, so that number doesn't really mean much. Idiot.)

(It was 11.2896 MHz, for those of you who are listening.)
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on August 10, 2016, 06:50:08 AM
Quote
Did you make any measurements of the Crystek? Was listening your only means of determining performance?

Dear Misguided "Expert":

Don't know about that idiot, but "we" have done both. "We" have tons of data on them. "We" do not use them.

Does that answer your question?
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on August 10, 2016, 06:51:52 AM
Quote
Have you measured a 24 MHz Crystek? Is there any reason to question their published performance?

Yes and yes.

Don't ask about 49 MHz.............................
Title: Re: They're talking about jitter......................
Post by: MystereoN on August 12, 2016, 06:17:25 AM
Do me a favor, and see if you can get John W to contact me. I have his Skype number.............well, it was................it no longer works.

Done.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 03, 2016, 11:40:30 AM
Quote
I used to use a granite surface plate a pneumatic isolators for phono. Worked well for structure born vibration. But acoustical stuff needs addressing.

You can actively correct for vibration, kind of like a txco or actively suspend the oscillator. Both intersting but nontrivial projects.

What in the hell is this so-called expert rambling on about? He seems clueless.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 03, 2016, 11:43:46 AM
Now, here is a guy who obviously NOT clueless. Probably because he actually works with RF, instead of just pretending RF is just some funny kind of audio, and all the same crap applies.

Quote
That is so typical for audio, that one of the minor aspects is singled out,
blown up beyond any proportion and that is then the benchmark in a
community. Be it FETs, use of iron in boxes, but in transformers it is ok,
but ferrite is bad again. OMG.

I can assure you that granite does not play a role in commercial oscillator design,
and a good oscillator can deliver stellar performance, just sitting on a lab table
but shielded from moving air.

Vibration sensitivity is a problem when you build a radar for a helicopter
where a crystal is multiplied up to 10 GHz and you get Doppler echoes from
slowly moving targets that are just 5 Hz off the transmitted carrier.

Anyone notice the most important line???

He gets it. The rest of that crowd..............especially the "experts"............clearly do not.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 03, 2016, 11:49:03 AM
Quote
It would be interesting to see what performance can be had using a Potato gate in a gate oscillator.

No, it wouldn't................you..........you...................you "expert".

Will someone please tell this guy to shut up, before he embarrasses himself, any more.

Wait, on second thought:

No, go ahead, show your ignorance. Maybe, just maybe, some of the outfits that throw money at you, for "consulting", will throw some money at some of the folks that I know. In which case, in some obtuse and circumlocutory manner, a pittance benefits might fall in my direction.

Unbelievable.....................
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 03, 2016, 11:56:55 AM
Quote
For the lowest "jitter" you need to go for the fastest logic, preferably 74AC series.

SERIOUSLY!!??!!??

I guess I am going to have to find some plots, of SC-cut crystal oscillators, made with cheap ol' TI LVC chips.

IOW, an unbuffered 04. Followed by a second one, to isolate it from the world.

Oh, and working at ROOM TEMPERATURE.

Oy vey....................they all seem to get more stupid by the day........................
Title: Re: They're talking about jitter......................
Post by: MystereoN on September 04, 2016, 03:30:18 PM
 ;D

Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 09, 2016, 01:01:32 PM
"Who is this man?"

Quote
I mentioned a while ago that I saw some measurements on the AT vs SC crystals.
They did not differ at close-to-carrier offset frequencies.

Very roughly:
the close-in PN is much more dependent on the ESR of the xtal, as this dictates the xtal self-noise.
Strangely not the Q of the xtal so much.

Here, the SC xtals are almost 10 times worse.

The close-in PN can be improved by increasing the current through the xtal (the Drive Level) and using AT cut xtals for their much lower ESR.
Both of which has been adressed in the RutgerS oscillator.

I seriously doubt that RutgerS oscillator's excellent performance at < 100 Hz will be improved upon by using SC-cut xtals.
Neither is it trivial to design a ”proper” mode-surpressor for SC based oscillators.

"Take him out, and............................."
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 09, 2016, 01:03:12 PM
Quote
can we draw any information about close in noise from ADEV measurements? I would think that there would be a good correlation but maybe i'm missing something. I would prefer than since I'm setup for ADEV.


YES! YES! YES! YES!

Time to earn that big consulting fee, bub.

Only don't ask me what the correlation is, since my measurements are obviously bogus.

Have a nice day.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 09, 2016, 01:04:51 PM
Quote
At lower f even SC-cut xtals operate at fundamental-mode.
For each additional overtone mode, the ESR increases.

Yeah, someone may need to put him out of his misery.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 09, 2016, 01:12:10 PM
Quote
Phase noise is short term variations in frequency. 'Close in " phase noise really is longer term variations in frequency. The region in question here seems to be in the 1 second to 100 Hz range, which is also the most difficult to measure.

Well, it is if you are not using the right gear. IOW, some DIY gizmo is not going to cut it. (We gave up on that approach, around 15 years ago.)

Then, there is that ADEV............................

Quote
And still finding a way to genuinely attribute sonic benefits in blind testing is needed. The current lit indicates that the audibility threshold is way higher than any of this stuff, whether for wow and flutter or for jitter.

Part of the challenge is confirming that the sonic difference is from the phase noise and not some other incidental change that could be significant.

Blah, blah, blah, blah, blah...................

I could 'splain it to you, but since my measurements are crap, and I am not published in some stupid "peer reviewed" (by idiot professors) journal, yeah, everything I have done will get ridiculed, so what is the point of 'splaining it.

Good luck continuing to flounder on the beach....................
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 09, 2016, 01:16:13 PM
Quote
Obviously, I look forward to measure the phase noise of all the oscillators to confirm the listening impressions, but at this moment I can't afford an Agilent E5052, so I have to wait until I will access the University Lab to do the measurement. In the meantime I will try to get the suitable stuff to do the JTest.

Oh, poor baby......................

If you didn't slag off the only person with the gear and knowledge of this stuff...................

But, you did. You know more than me. Sod off!

Have a nice day.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 09, 2016, 01:21:47 PM
Quote
i know this is a high end design, but maybe there is a ''budget'' oscillator available that would be cheaper than the commercial ones (like the popular crystek's or ndk's) that would perform better than these and ''give a taste''....?

Good question. Might be hope for this lad.

Actually................no!

If there was, you-know-who would be building them, and selling them.

To manufacturers. Not cheap-@$$ DIYers.

BTW, the Craptek 22/24 ones...................can anyone 'splain why they have the same phase as the 45/49 ones?

Anyone see anything wrong with that?  Hmmmm........................?

BTW, don't expect them to meet spec, because a lot don't.

Which ones are more likely to meet spec................exceed spec...............not meet spec......................etc.

Yeah, guess who knows that answer. It will cost you $$$$$ to find out.

You can find out where to send PayPal donations...............................
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 09, 2016, 01:23:05 PM
Quote
Vibration can easily induce high levels of "close-in" noise on the oscillator output.

That is why I still remain slightly sceptic to the idea of close-in PN as being the single most mportant parameter for audio clocks.
In a listening room environment, all that hard work of lowering the close-in PN is wasted once the enclosure and the xtal start vibrating to the music.

Yet upgrading the clock seems to improve the percieved sound...

Can it be something else than just close-in PN??

Please, stop now....................................
Title: Re: They're talking about jitter......................
Post by: MystereoN on September 10, 2016, 02:53:38 PM
Quote
BTW, the Craptek 22/24 ones...................can anyone 'splain why they have the same phase as the 45/49 ones?

Anyone see anything wrong with that?  Hmmmm........................?

45/49 should have 6dB worse noise figures as 22/24 ones ..... somebody is writting fairy tales in datasheet
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 11, 2016, 04:00:59 PM
Right........should be 6 dB difference.

Which really means....................the 22/24 ones are crap.

Also assumes the 45/49 ones meet spec.................

Ha, ha, ha!
Title: Re: They're talking about jitter......................
Post by: MystereoN on September 11, 2016, 04:08:33 PM
Ha ha
I don't care about Craptek, still running on 11.2896  :)
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 11, 2016, 04:27:17 PM
Yeah, but if you have a reel of NDKs, the right gear, a lot of spare time..............and a flip-flop......................you can use 22.whatever MHz.
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on September 14, 2016, 12:37:51 PM
Oh, crap....................they are back on the vibration crap..............again.

Yes, you truly are a Fluke of the Universe. We are laughing at you.

Give up.
Title: Re: They're talking about jitter......................
Post by: MystereoN on September 15, 2016, 02:08:11 AM
worrying about vibrations .... but don't worrying about using Craptek oscillators  ;D
Title: Re: They're talking about jitter......................
Post by: MystereoN on January 11, 2017, 08:43:53 AM
here we go again...
http://www.diyaudio.com/forums/digital-line-level/301009-s-pdif-pll-8.html#post4947698 (http://www.diyaudio.com/forums/digital-line-level/301009-s-pdif-pll-8.html#post4947698)
Title: Re: They're talking about jitter......................
Post by: Gen. Dreedle on January 26, 2017, 10:24:40 AM
Not too long ago, we made some measurements of old Toshiba TOSLINKs vs the crappy brand that you can buy at Mouser. Since the folks we did this for prefer to keep it private, I can not share it.

Let's just say they get worse as speed increases. The HS version is better than the regular version. Main conclusion is the RX have crappy, noisy (Chinese) transistors, and the TX LEDs are just ok.

All have a high noise floor. Which may or may not be important. Since SPDIF already has a high noise floor....................

The difference is the TOSLINKs have just plain ol' noise, and the SPDIF has correlated noise.

The only reason why SPDIF sounds ok is that nothing that you do affects the phase noise below 10 Hz or so. Eventually, the noise floor intersects the source phase noise, and that is that.

End of story.

No more help or clues.

Screw you guys.........................!
Title: Re: They're talking about jitter......................
Post by: MystereoN on June 19, 2017, 11:29:29 AM
Somebody is famous at DiyA  ;D

(http://jockohomo.net/forum/index.php?action=dlattach;topic=182.0;attach=240)