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

SCAudiophile

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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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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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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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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.
 

cykin

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Mar 23, 2022
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Hi everyone,

I have just brought OP21A-D and found there is an Output level switch; LOW: 1.6 Vp-p HIGH: 3.0 Vp-p (4 system common switching 50 ohm). I am not quite sure of the function/difference of both selections.

I am going to connect it to N01XD. Please advise, thanks.
 

stevebythebay

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Oct 21, 2012
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Hi everyone,

I have just brought OP21A-D and found there is an Output level switch; LOW: 1.6 Vp-p HIGH: 3.0 Vp-p (4 system common switching 50 ohm). I am not quite sure of the function/difference of both selections.

I am going to connect it to N01XD. Please advise, thanks.
Seems that it would be advisable to contact Esoteric and Cybershaft (Kenji, who’s email is hasegawa@cybershaft.jp) to ascertain both the specific function of the setting and what is preferred based on whether using 50 or 75 ohm for the specific OP21 output. I’m assuming your dealer won’t have that level of knowledge, but I may be wrong.

Maybe others on this forum have more specific insights.
 
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SCAudiophile

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The N-01XD's only clock input is 50-ohm so make sure the dip switch (or switches if you bought a multiple output
model) are set to the 50-ohm setting. As an aside, if you bought a multi-output model of clock and will only connect
the N-01XD for now (or anything less than max number of outputs), I'd suggest using 50-ohm terminators on the
unused outputs. This is good hygiene in general for any clock, master clock, word clock, Cybershaft or not IMHO.

The switch you are referring to is for signal output strength as I understand it. For my own setups involving P03-U/D-03,
P-02/D-02 and now Grandioso P1/dual D1 stacks, "LOW" works perfectly and also yields a touch better sonics and
consistently shorter sync times. "HIGH" is reserved as I understand it for units that may expect or need higher signal
strength on their clock inputs to achieve sync.

As mentioned, in 3 generations of Esoteric gear, I've found LOW best and this has also tied with testing I've heard was done
by Cybershaft as well as many of their users.

I do not own the N-01XD however; I'd suggest writing Cybershaft at either the email given above ( hasegawa@cybershaft.jp ) or cybershaft777@yahoo.co.jp.

I'd also hazard a guess that like the multiple models I've owned the switch was set to LOW out of the box as that is
how it was tested and certified before shippings.

There is also a toggle switch for GROUND on later models (Chassis or ISOLATE); please consult the instruction guide and/or
write to them to seek advice for your setup as to which setting works best.
 

cykin

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Mar 23, 2022
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I have talked to Kenji and he is very helpful with my questions.

The input specification for the external 10MHz clock of the Esoteric N01XD you are using is 50ohm 1.0Vrms.

Therefore, the OP21A-D settings that meet the specifications are as follows.

Clock cable : BNC 50ohm Impedance ( The cable you have already ordered from us. )

Output level : LOW 1.6Vp-p

Output impedance : 50ohm

GND setting : isolate

Theoretically, the above settings are valid, but for audio equipment, the theory and practice may differ.

This is because the environment and circumstances in which the device is used vary from user to user.

Other than the above settings, you may get the situation you like.

Therefore, we recommend that you try all combinations of Output Level and GND settings.

There is no risk of damaging connected devices in all settings.
 
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