Reality is Cruel : Cybershaft new Ultimate OCXO 10M Clocks Shootout OP20 vs OP17

SCAudiophile

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Sep 11, 2010
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To get the best measuring clock and then introduce impedance mismatches has seemed counter-intuitive to me. Some are saying though that impedance mismatches matter far less though with sine wave than with square wave. Which type of clock signal yielded the side effects you folks heard?
Both; varying degrees of impact.

People tend to focus on square versus sine wave, using that to argue the point, and yes, I do get the difference certainly.

It "may" matter less with sine wave than square (stress this word as those who have said that had a long way to go to prove it so I categorize it as just opinion and something that is possible but not proven), however, that is not to say it does not matter at all.

I've always wondered though why this is one area of audio where some would advocate ignoring the fact that the manufacturer
had thought to pick a spec to follow, mark it, include it in the manual, etc..

I don't know all the answers, far from it; I do tend to practice "RTFM" figuring if the vendor followed a spec, I probably should too.
 

kennyb123

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Nov 30, 2012
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I've always wondered though why this is one area of audio where some would advocate ignoring the fact that the manufacturer
had thought to pick a spec to follow, mark it, include it in the manual, etc..
In a hobby where we repeatedly see that “everything matters”, it is a little surprising that some would ignore this. But maybe some have to because they face constraints. It surprised me that so few clocks support simultaneous 50 ohm and 75 ohm outputs.

As an aside, on Friday my REF10 returned from Mutec with the SE120 upgrade. The oscillator they selected actually measures -121 dBc at 1 Hz. The clock has barely settled in and yet it brought a tremendous upgrade.
 

SCAudiophile

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I agree with you kenny123 on that and are there are those that face constraints. Also, the truth is, going back a few years there were not many high quality 50-ohm cables. At that time we have Esoteric Mexcel 8N-A2000 (an excellent cable, owned 2) 50-ohm, Evolution Acoustics 50-ohm, and a very few others that all commanded steeper prices so those who would rationalize (as there were constraints) did so more frequently. Now, years later, there are many high-quality 50-ohm cables with proper 50-ohm terminations available from quite a few vendors including Habst, Shunyata and a quite a few others at various price points.

Some make the statements out of ignorance and others for various other reasons. There are still others, e.g. one dealer, who was quoted on his forum as saying "his actual testing verified that it didn't matter and it so happened that his favorite for-sale brand's 75-ohm cable was the best...." when in fact that brand did not make a 50-ohm cable. Seemed a bit convenient to me at the time,...perhaps I'm just cynical on this point <LOL>.

The differences are subtle in some cases and more pronounced in others however I do tend to believe based upon much trial, error and focused listening that it does make a difference.
 

QuadDiffusor

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Apr 3, 2017
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From AXPONA 2022, the world-debut of Aurender’s MC20, with a MSRP of US$30k+ Personally, I’m confused about the merits and necessity of the expensive rubidium clock; its ultra-low long-term time drift is actually not as relevant as low phase noise offset (ideally, less than -120dBc at 1Hz), already available through calibrated and stable OCXOs in proven designs from Cybershaft and Mutec.
 

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CKKeung

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Jun 18, 2011
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Hi John,
USD3xk is a big sum!

But I examined you photo carefully and noted that there were already two ocxo clock modules on the circuit board of this MC20 ext clock.
Why need the rubidium clock module?
IMG_20220427_173508.jpg

And I have never seen an ext clock with replaceable rubidium clock module.

I think Aurender must have some tricks up their sleeve!
:p
 

QuadDiffusor

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Apr 3, 2017
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Hong Kong
Hi John,
USD3xk is a big sum!

But I examined you photo carefully and noted that there were already two ocxo clock modules on the circuit board of this MC20 ext clock.
Why need the rubidium clock module?
View attachment 92102

And I have never seen an ext clock with replaceable rubidium clock module.

I think Aurender must have some tricks up their sleeve!
:p
CK, the OCXOs are for 44.1k and 48.0k word clocks, whereas the rubidium oscillator is for the 10.0000MHz sine master clock. It’s the latter which I have reservations about.
 

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