Author Topic: They're talking about jitter......................  (Read 6194 times)

Gen. Dreedle

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They're talking about jitter......................
« on: December 30, 2012, 10:08:39 AM »
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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.
"Major Danby, sir."
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"Take him out and shoot him."
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"I said take him out and shoot him. Can't you hear?"

seagreen

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Re: They're talking about jitter......................
« Reply #1 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.
No double blind testing was used in the making of this post.

Gen. Dreedle

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Re: They're talking about jitter......................
« Reply #2 on: December 30, 2012, 09:20:42 PM »
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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.)
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

seagreen

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Re: They're talking about jitter......................
« Reply #3 on: December 31, 2012, 06:30:15 AM »
My theory is that the high sunspot count is affecting people's brain activity.
No double blind testing was used in the making of this post.

MystereoN

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Re: They're talking about jitter......................
« Reply #4 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

Fascinating historical stuff
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Gen. Dreedle

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Re: They're talking about jitter......................
« Reply #5 on: January 16, 2013, 06:05:53 AM »
Is it really 41 minutes long?
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

Gen. Dreedle

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Re: They're talking about jitter......................
« Reply #6 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

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.)
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

seagreen

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Re: They're talking about jitter......................
« Reply #7 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#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?

No double blind testing was used in the making of this post.

Gen. Dreedle

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Re: They're talking about jitter......................
« Reply #8 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."
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

seagreen

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Re: They're talking about jitter......................
« Reply #9 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

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.

No double blind testing was used in the making of this post.

Kryten

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Re: They're talking about jitter......................
« Reply #10 on: July 26, 2013, 11:26:03 PM »
Been fixing and listening to audio for waaay too long....

Gen. Dreedle

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Re: They're talking about jitter......................
« Reply #11 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.
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

Gen. Dreedle

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Re: They're talking about jitter......................
« Reply #12 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.
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

MystereoN

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Re: They're talking about jitter......................
« Reply #13 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
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then beat you with their experience!!!

Gen. Dreedle

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Re: They're talking about jitter......................
« Reply #14 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!
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"