CLOCKS, what should we look for in next generation

[austinpop]

2 hours ago, jabbr said:

That's all just terrific. Of course the transmission line length has effects: https://dl.cdn-anritsu.com/en-au/test-measurement/files/Technical-Notes/Technical-Note/MP1800A_EE1100.pdf

 

of course this is well documented. Now what is the phase error when the clock is converted to something usable for audio? ... and of course the question about the phase error of the DAC logic itself or whatever is being clocked. 

 

the problem is that the clock can't improve the phase error of the clocked circuit better than the best it can be, just as a low 1/f PSU feeding a high 1/f transistor can't make the transistor better than it can be...

 

issues such as: https://ac.els-cdn.com/S1877705812008636/1-s2.0-S1877705812008636-main.pdf?_tid=e19ed90e-ce44-11e7-834b-00000aacb35e&acdnat=1511218278_747e5edcf586778a9501c9ff0176ae6c, https://www.researchgate.net/profile/Rui_Aguiar/publication/4297963_Predicting_noise_and_jitter_in_CMOS_inverters/links/00b4951bed2dfe7cc4000000/Predicting-noise-and-jitter-in-CMOS-inverters.pdf

 

I envy your grasp of the technical aspects of this stuff. Bravo!

 

Like @zephyr24069 's previous reference clock - I use a reference clock with phase noise of -114 dBC/Hz @ 1Hz. It drives the frequency synthesizers in the SOtM sCLK-EX, for which phase noise specs have never been published - boo, hiss!

 

I do understand that what the Lord giveth with low phase noise at the OCXO source, He taketh away with transmission line length, reflections, etc. Still it is important to understand that the net effect is still an outstanding improvement in sound quality!

 

It IS important to understand the nuances on clock distribution, as well as the importance of excellent PSUs for clock generators, and I have written about it - albeit not at this level of expertise. But it should not detract from the key point that clock improvements of this nature do improve the SQ tremendously.

 

I can't stop listening to my system these days - it is so scary good!

[austinpop]

12 hours ago, PeterSt said:

 

I have a secret for you : the normally educated EE doesn't know much about these things. Say that this is because audio(philia) is not a real target (there is no education for it).

 

As a nominal PhD/EE (although my research was in networks) I would agree with you wholeheartedly!

 

On the whole EE subject - I should clarify that Electrical Engineering (what I did in my Bachelor's) and Electronics Engineering are actually somewhat different fields. And then, when you get into audio engineering, I'm not sure that's even a degree program anywhere. This is why you get into this realm of opinions. The link between engineering metrics and sound quality is still tenuous, even after all these decades. Rather than causality, we often only have correlation.

 

This is a fertile breeding ground for the cult of the personality.

[austinpop]

On 1/22/2019 at 2:42 PM, gordec said:

This is a very interesting thead to read as clocks is probably one of the last things on an audiophile’s journey to experiment with. I’m trying to experiment with external clocks for my Pro iDSD since it takes external clocks. How do I know if a clock would be an upgrade because the Pro iDSD has a high quality clock built in?

 

You can read about my experiments with a Ref-10 with the Pro iDSD here: 

 

 

[austinpop]

7 minutes ago, Superdad said:

BTW, here's the plot for an eye-poppingly great OCXO we have been looking at.  Have no idea the cost yet--likely $600 a piece.  But check it out: -110dBc/Hz at 1Hz, -143 at 10Hz!  (this is 10MHz part, but even in the mid-twenties audio clock range these are spectacular).

 

 

Clock porn!