Gee, I should have read more of the thread.......
"Accuracy", when it comes to clocks in CD players is not worth diddly-squat. Low phase-noise and jitter are important. They kinda go hand-in-hand, but it is possible to make a low-phase noise oscillator and then screw it up when you turn it into a square wave, and the jitter is lousy.
The practice of ovenised clocks has not disappeared. Just isn't always needed, pracitcal, or economical.
Like in a CD player.
Jocko
"Accuracy", when it comes to clocks in CD players is not worth diddly-squat. Low phase-noise and jitter are important. They kinda go hand-in-hand, but it is possible to make a low-phase noise oscillator and then screw it up when you turn it into a square wave, and the jitter is lousy.
The practice of ovenised clocks has not disappeared. Just isn't always needed, pracitcal, or economical.
Like in a CD player.
Jocko
Jocko Homo said:
So, as the original idea of this thread was 'what is the best performing clock', what is the best low phase-noise oscillator and what is the best way of turning into a square wave without 'screwing it up'?
I also find it hard to believe that 'accuracy when it comes to cd players is not worth diddly squat.' I have a xtal from a cd-p of 33.8688Mhz. I also have one of 33.000Mhz. Are you telling me I could exchange one for the other without any effect?
Andy
poynton said:
Hi,
In this case doesn't the xtal frequency need to be a integer multiple of the cd format ? (I don't think 33.000MHz is)
Accuracy, and precision.....
I always got pulled up at university for mixing them up!
http://www.flatsurv.com/accuprec.htm
http://en.wikipedia.org/wiki/Accuracy_and_precision
Kind regards,
Ashley.
poynton said:
in your particular example you will hear it, but when we stay within the redbook spec (+/- 100 ppm), no difference can be heard.
To clarify, this is about static errors, where we use ppm's. It strikes me that some commercial clock suppliers still specify this as being 'the" major specpoint of their clocks. Others try to convince you using a spectrum analyser measurement where 100 kHz (!) resolution bandwidth is used......
Lower jitter = better
However, at a certain moment we get into the ps range, and things then are hard to measure but still audible.
Similar clocks may sound different as the jitter spectrum differs. In addition, not all DAC chips react in a similar way to jitter.
best
As for performance, in terms of phase noise........it isn't that simple. It will have a frequency distribution (did anyone read the link on phase noise?) Some will say close-in noise is important; others will say absolute noise floor is.
When it comes to "not screwing it up"........
Well, hard to make things idiot proof, as idiots are so damn ingenious. One sure-fire way to muck it up is to stick it into a '04 gate, and use the other 5 gates in the chip. 6 signals.........one ground pin and one supply pin.........6 dB PSRR at transition.............nope, not a good idea. But one that you see all the time.
Accuracy means it can be......I forget............+/-500 ppm to meet Redbook. So, no, 33 MHz can't sub for 33.868.8 MHz. It can be off several kHz, and most people can not tell a difference.
If it wobbles so much that you hear pitch-bending..........then you most likey don't have a crystal oscillator. Hard to make one drift that much, that fast.
How to measure..........? Read the link. And, yes, I can make those measurements. Although I do not have data on any clocks other than my designs, because I don't care about other designs.
Especially Elso's!!!! [joke]
He knows why...............
Jocko
When it comes to "not screwing it up"........
Well, hard to make things idiot proof, as idiots are so damn ingenious. One sure-fire way to muck it up is to stick it into a '04 gate, and use the other 5 gates in the chip. 6 signals.........one ground pin and one supply pin.........6 dB PSRR at transition.............nope, not a good idea. But one that you see all the time.
Accuracy means it can be......I forget............+/-500 ppm to meet Redbook. So, no, 33 MHz can't sub for 33.868.8 MHz. It can be off several kHz, and most people can not tell a difference.
If it wobbles so much that you hear pitch-bending..........then you most likey don't have a crystal oscillator. Hard to make one drift that much, that fast.
How to measure..........? Read the link. And, yes, I can make those measurements. Although I do not have data on any clocks other than my designs, because I don't care about other designs.
Especially Elso's!!!! [joke]
He knows why...............
Jocko
Uh...........may have been in another thread. Senior citizen moment. Again.
Yeah...........here it is:
http://www.diyaudio.com/forums/showthread.php?postid=782617#post782617
Heh, heh...this thread was rather amusing at one time. New expert on the block wanted to pound his chest.
Pounded with rotten tomatoes, more like!!!!!! "Clan Abruzzese" strikes again, eh?
Jocko
Yeah...........here it is:
http://www.diyaudio.com/forums/showthread.php?postid=782617#post782617
Heh, heh...this thread was rather amusing at one time. New expert on the block wanted to pound his chest.
Pounded with rotten tomatoes, more like!!!!!! "Clan Abruzzese" strikes again, eh?
Jocko
I am sort of in the dark on this clock thing and just stumbled onto this thread. Maybe this is a good place to ask this, as something good may come out of it...maybe the 'best' clock!
something I've wondered for a while...
What If I took a ... say ..15Mhz rubidium (stratum 2?) telco oscillator and used a frequency divider? Is this an 'off the wall' idea or is it feasible with good/ great/ incredible results??
...or maybe just a high quality ~1 gig oscillator used in microwave transmissions ??
regards,
Marc
something I've wondered for a while...
What If I took a ... say ..15Mhz rubidium (stratum 2?) telco oscillator and used a frequency divider? Is this an 'off the wall' idea or is it feasible with good/ great/ incredible results??
...or maybe just a high quality ~1 gig oscillator used in microwave transmissions ??
regards,
Marc
It has been suggested before..........many times.
How are you going to get 11.2896 or 16.9344 or 33.8688 MHz out of any of those???????
The "high quality" microwave "bricks" we used to use had a comb generator and a multiplier in them. Eventually, Fujitsu came up with a DRO (dielectric resonator oscillator) that did not use a crystal. They all worked ok for FM, but trying to pass 256 QAM with them was a nightmare.
That is why they invented fiber optics. Got rid of microwave radios and the guys like me who designed them. Hello unemployment line...........
Jocko
How are you going to get 11.2896 or 16.9344 or 33.8688 MHz out of any of those???????
The "high quality" microwave "bricks" we used to use had a comb generator and a multiplier in them. Eventually, Fujitsu came up with a DRO (dielectric resonator oscillator) that did not use a crystal. They all worked ok for FM, but trying to pass 256 QAM with them was a nightmare.
That is why they invented fiber optics. Got rid of microwave radios and the guys like me who designed them. Hello unemployment line...........
Jocko
Well, I'm surprised.
4 pages into this thread and nobody has posted a comment along the lines of "X is better than Y because of Z".
Which leads me to wonder: is there any real (noticable performance) difference between an XO2, Trichord4 or Kwak? Or does it come down to implementation? Ie, avoid shoving it through a '04.
4 pages into this thread and nobody has posted a comment along the lines of "X is better than Y because of Z".
Which leads me to wonder: is there any real (noticable performance) difference between an XO2, Trichord4 or Kwak? Or does it come down to implementation? Ie, avoid shoving it through a '04.
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