Jitter -- How low is low? - Page 3

Yep, so we have nothing to fear from jitter.
Talking about the CS8414: whilst discussions are held about the various DAC chips and opamp, next to no attention is paid to the digital receiver. The CS8414 is perhaps the most musical of all the receivers. It is however now only available to specialist users, whilst the general public has been forced to use the CS8416, which I find far less musical to my ears. The DIR9001 and WM8805 are just as disappointing when connected to the same DAC chip and audio output, even though they all have better jitter performance figures than the CS8414.

As an electrical and accoustical engineer, I disagree at least in part with the article that suggests that PPM has little to do with the measure of Jitter. The piece is a bit of a marketing angle, but correctly states that there are other, external considerations other than the PPM oscillation expressions. On closer inspection, the quoted piece is at least incomplete as it does not provide any perspect on the type of measurement clock used etc.. For example, piece doesn't indicate the type of clock used, or any aspect of stabilization etc. In crystal oscllators, (like XO word clocks for example and those used by Esoteric, Apogee and others), PPM can be a very helpful refrence for the determinaion of stabliztion of a frequency (whether affected by jitter or otherwise) within a frequency range. In these types of oscillators, a quartz fragment ofis employed that is stimulated with electricity to the point that it resonates. The resonnance is typically at a frequency correlated to the size and orientation of the crystal. Once the oscillator circuit becomes stable, crystals resonate at a very stable frequency where the accuracy is generally in the 100 ppm (parts per million) range. For those scoring along at home, that means that a crystal with a nominal frequency of 80 MHz might resonate at anywhere between 79.99200 and 80.00800 MHz. The article might make more sense if it made the point I assume that it is attempting to make more directly. Tht is; that crystals are somewhat susceptible to variations in temperature among other factors and great care is taken in oscillating clocks to provide stable environments.

As an electrical and accoustical engineer, I disagree at least in part with the article that suggests that PPM has little to do with the measure of Jitter. The piece is a bit of a marketing angle, but correctly states that there are other, external considerations other than the PPM oscillation expressions. On closer inspection, the quoted piece is at least incomplete as it does not provide any perspect on the type of measurement clock used etc.. For example, piece doesn't indicate the type of clock used, or any aspect of stabilization etc. In crystal oscllators, (like XO word clocks for example and those used by Esoteric, Apogee and others), PPM can be a very helpful refrence for the determinaion of stabliztion of a frequency (whether affected by jitter or otherwise) within a frequency range. In these types of oscillators, a quartz fragment ofis employed that is stimulated with electricity to the point that it resonates. The resonnance is typically at a frequency correlated to the size and orientation of the crystal. Once the oscillator circuit becomes stable, crystals resonate at a very stable frequency where the accuracy is generally in the 100 ppm (parts per million) range. For those scoring along at home, that means that a crystal with a nominal frequency of 80 MHz might resonate at anywhere between 79.99200 and 80.00800 MHz. The article might make more sense if it made the point I assume that it is attempting to make more directly. Tht is; that crystals are somewhat susceptible to variations in temperature among other factors and great care is taken in oscillating clocks to provide stable environments.

pps = pulse per second. = measurement for clock.
ps = pico second = measurement for jitter.

Yes, frequently, look at American TV adverts, comparisons between painkillers, athletes foot treatments, heartburn pills, kitchen towels and so on, this may be not allowed by UK TV authorities but it is far from a universal policy. (I spent 10 years living in the USA)


No, but I am not making any outrageous claims for my kit. Though I have seen the measurements that Stereophile did on my DAC and I can compare that against similar products, however that would be largely meaningless as even really average kit has superb measurements these days.


To some extent, however claiming that a DAC or a CD player sounds good is different from claiming that one cable will be better than another when all it does it transfer a digital signal. There is a good deal more "plumbing" in a DAC than a digital cable.

So I must accept all opinions equally ?, surely some opinions are more valuable than others. Also it seems to me that the bigger the claim the more evidence is required.

What I could do is this. I have several different digital coax cables. I could use each in turn to connect my transport to my DAC, then I can record the output from the DAC and see if there are any differences. I could use each cable several times to allow for sample variability.

* *************************************************
* I have successfully been able to demonstrate actual measurable *
* differences (small) between different CD players analog outputs *
**************************************************

I can then load the recorded tracks in an ABX comparator and see if I can tell a difference or I could host fair use small segments of them for others to try out. If the null hypothesis was supported would you grant that it was likely that there was no difference with my given cables and given DAC ?

I could of course use a bit-comparator or Audio Diffmaker to do more controlled tests.

Nevermind. It appears you're one of those people who doesn't know what "theory" means in the context of science.

I'll say it again. Science is as sure that nothing can go faster than light as it is sure of any trivial fact, such as that things fall when you drop them or that the earth goes round the sun.

But anyway, back to the regularly scheduled action. I'm quite fascinated with the subject matter here.

...as far as theories go look up Godel's Incompleteness Theorem

http://en.wikipedia.org/wiki/G%C3%B6del's_incompleteness_theorems

Listening tests performed in a perfect vacuum would clear this all up! So let's gather all the power cord & clock proponents and get them on the next shuttle launch!

There comes a point where pragmatics comes into play. Even if you can never prove that (for instance) jitter is inaudible in commercial kit under all circumstances if you run test after test (properly controlled blind tests of course) and each time and each variation of the test you get the null result (the situation that currently holds) you reach a point where there does not seem much mileage in carrying on. You might never be able to prove inaudibility but it becomes something that does not appear to be worth pursuing any futher. This may explain why there have been no more jitter audibility papers in the last three years ?

Well don't you understand, he is saying Jitter effects are metaphysical. Why is that so hard to grasp


Now as much as I don't believe in Jitter audibility especially after experimenting with the DIR9001 I am going to build a DAC based on Guido Tent's VXCO PLL synch-reclocking.

But I think the whole high end clock upgrade trend has gained momentum because it is not something that people can ABX.


.

I installed "quantum purifiers" in my HP and now I can divide by zero!

Ofcourse you can! If your clock is replaced with a new clock AND it sounds better then the improvements must be because of the new clock, it's that simple.

I am not interested in theory, only to know how it works. I only listen with my ears and if something makes the cdplayer sound better, i am happy.

There's no gain in discussing this unless you heard the difference between the old clock and the reclocking device.

I am in the market for a reclock upgrade as part of a total cdplayer mod. Thus far, every step made the cdplayer sound much better.

The problem is people have almost zero hearing memory. By the time you take a CDP apart and install a clock your mind has forgotten what the sound was.

The only way to settle this would be to have two identical CDP's and install a clock in one then do a blind ABX between the two. My guess that people couldn't identify any difference.

But I hope I am wrong because I am investing some $'s in a fancy tent labs reclocking DAC.

That is NOT necessarily true. if you own your cdplayer for a long time and "know" how it sounds, you'll hear differences for the good or the bad on a longer term listening!

Yes, i am also looking into the tentlabs reclock and psu.