John Swenson tutoring paper: "Considerations regarding usage of external reference clocks" (EtherREGEN and other): Sine vs. square, impedance, cables—and a money saving surprise at the end.

[Exocer]

9 hours ago, Superdad said:

 

For $19 you could try this board:

https://www.ebay.com/itm/OCXO-adjust-PCB-Power-supply-voltage-12V-suitable-for-51X51-51X41-package/313123416940?

 

But desoldering the OCXO from the BG7TBL board may not be terribly easy depending upon how tight those holes are since you have to get all the solder connections to let go so that you can pull the part.  Attempt at your own risk and please don't ask me anything about the above linked board. I just found it on the net and looks to be clean and simpler--a lot simpler than all the unnecessary circuitry that is on the BG7TBL boards.

Thanks and I have already switched from the FE-180 to the Symmetricom clocks being shipped with more recent BG7TBLs out of curiosity so I am familiar with removing he OCXO from the default board at this point. Rest assured there will be zero follow-up from me RE the above board you've linked to. This will just be a simple experiment since I now have the Symmetricom and FE-180 to play with.

 

Cheers and thank you!

[LEO SOUND]

I quote the info on the Sotm clock.

 

"As many audiophiles know, the clock signal is an angled square digital signal, but the sCLK-OCX10 produces a pure analog sine wave of 10 MHz, and this sinusoidal clock signal is the method adopted for the best clock performance because it produces significantly less noise than the angled square digital clock signal. In order to implement this, the sCLK-OCX10 consists of only analog circuitry which contains 10 years of know-how of SOtM, it derives high analog sound that is different from other master clocks on the market which output angled square digital clock signals."

 

Sotm explain a little what John @JohnSwensonjust wrote on his white journal?
On the sotm clock, the filter can be integrated then also?

 

Mutec REF 10 generates a square wave which must be excellent I think.

 

My Sunday evening question:
Insofar as the black phases of the two products Sotm and Mutec are excellent, in theory the Mutec must be "better" because it is square?

 

 

[Superdad]

1 hour ago, LEO SOUND said:

On the sotm clock, the filter can be integrated then also?

 

“Integrated”, as in filter built into the clock box? Not applicable assuming the box is producing a clean sine wave in the first place (which for the $3,500 SOtM I expect they are). 
No, the point of the low-pass filter is to place it at the far end of the cable (in our case at the EtherREGEN) so that you then don’t have worry about using short and very stiff semi-rigid clock cabling.

 

As well, and perhaps as important, the filter (again, only for sine wave clocks—don’t put one on a square wave!) will assure a very clean, free from harmonics and noise sine, regardless of what might have been transmitted by the clock or picked up the cable.

This is very important because (seen if you read John’s paper carefully) the circuits receiving 10MHz clocks—which always involve a clock synthesizer since that 10MHz is always turned into some other frequency(s)—are quite sensitive to harmonics. They would prefer a really good square wave, but if you feed them a sine wave it would best be an extremely clean one.

 

The above is really a key point of John’s paper so I hope everyone will ponder it further.  But try not to read too much or too little into it. 

 

—Alex C.

 

P.S. Anticipating the other obvious question regarding SOtM (not that I want to talk about their products): Their large clock board, (fitted in all of the “Ultra” models as well as the $1,700 version of their switch) uses a crystal as reference to an older Silicon Labs clock synthesizer—or, when extra is paid to have a BNC jack, the synth gets programmed to use an external 10MHz reference. Like every other (as explained above), that board would prefer a great square wave but will accept a (hopefully very clean) sine wave. Their clock board input contains neither an active sine>square converter chip nor a passive low-pass filter.

So the things we wrote about sensitivity to various factors (say with EtherREGEN) apply to the SOtM units as well. (Again, I am not referring to their OCXO clock box.)

[R1200CL]

5 hours ago, Exocer said:

This will just be a simple experiment

Please share in the clock tread. Your contribution is of great value to the rest of us. You can get very cheap versions of the BG7TBL at AliExpress, probably some with direct wiring to BNC connector. 

[R1200CL]

@Superdad

What version of the BG7TBL did you get ? The one claiming to be square and 75 ohm ?

 

Have @JohnSwenson put it on some sort of measurements ? Or intend to do ?

(if ever, time allows). 
 

Was it a Prince 50 ohm sine the other clock ?

[R1200CL]

If any help.

I guess some sort of group buy is needed. But I think it’s also quite clear by now, the 50 ohm version will just do. 
—————————————————————————————————————

Hi Andreas

Thanks for your email

The BLP-10.7-75+ is a non-catalogue part and is not recommend for any new designs, is this request a one off request or will you require this part again in the future?

Best Regards,

Dan Pearson.

.minicircuits.com

[Superdad]

13 hours ago, R1200CL said:

What version of the BG7TBL did you get ? The one claiming to be square and 75 ohm ?

Yes, the one labeled as having both sine and square wave outputs—with 75-Ohm BNC jacks.

 

13 hours ago, R1200CL said:

Have @JohnSwenson put it on some sort of measurements ? Or intend to do ?

He already looked at circuit and the waveforms. And it wasn’t pretty.

No current plans to run phase noise plots as we see no point and he is very busy with other development work.

 

6 minutes ago, R1200CL said:

But I think it’s also quite clear by now, the 50 ohm version will just do.

That’s what we have been saying from the start! (With sine wave and filter at the target end of the cable.)

[Duckworp]

@SuperdadI am not so technically minded as many here so do not fully understand.  I have a SOtM sCLK-OCX10 which is connected to my EtherREGEN and to an SOtM sms-200 Neo.  Would this configuration benefit from two mini circuits items, one on each unit that connects to the clock?  If so would you know where to buy this item?  I am in the uk and cannot see it for sale anywhere.  Thanks for your help. 

[R1200CL]

3 hours ago, Duckworp said:

If so would you know where to buy this item?

They ship from UK. 
https://www.minicircuits.com/WebStore/dashboard.html?model=BLP-10.7%2B

 

Soon out of stock 😀

[MartinT]

My Mini-Circuits BLP-10.7-75+ has just shipped.  Running sinewave into the ER, this seems well worth trying.

[Tokyokyoto]

This one is from mini- circuits.  Weighs as much as the clock (almost)
One coming from Mouser on Thurs.

 

I have the $99.00 clock but not sure hat wave or impedance.  It does have 50 ohm taps though.

[soares]

5 hours ago, Tokyokyoto said:

This one is from mini- circuits.  Weighs as much as the clock (almost)
One coming from Mouser on Thurs.

 

I have the $99.00 clock but not sure hat wave or impedance.  It does have 50 ohm taps though.

Any impressions?

Thanks,

Jorge

[Tokyokyoto]

IWell at the very least, no harm done.  Last night I was streaming Qobuz and came upon a fantastic live performance recording that just blew me away.  Sound was spot on, but more important I was rockin’ out.  

I wasn’t able to put in the filter until just before dinner tonight.  I decided to do some tidying up at the same time which meant me unplugging, plugging and shifting stuff around.

I dropped the needle and streamed another(different) live performance and I was again immediately transported, seemingly quicker than usual, and the analytical perception was that there were less boundaries/more open.

I didn’t get to anything with vocals though which for me/my system is the toughest.  I think by tomorrow evening I will know the if, what and why, but I think a good start. 

I have an additional filter coming soon earmarked for another component.  I think that if there are benefits to be had the  cumulative enhancements will be easier to hear.

[soares]

1 hour ago, Tokyokyoto said:

IWell at the very least, no harm done.  Last night I was streaming Qobuz and came upon a fantastic live performance recording that just blew me away.  Sound was spot on, but more important I was rockin’ out.  

I wasn’t able to put in the filter until just before dinner tonight.  I decided to do some tidying up at the same time which meant me unplugging, plugging and shifting stuff around.

I dropped the needle and streamed another(different) live performance and I was again immediately transported, seemingly quicker than usual, and the analytical perception was that there were less boundaries/more open.

I didn’t get to anything with vocals though which for me/my system is the toughest.  I think by tomorrow evening I will know the if, what and why, but I think a good start. 

I have an additional filter coming soon earmarked for another component.  I think that if there are benefits to be had the  cumulative enhancements will be easier to hear.

Mine arrives tomorrow. I will post my findings also. Thank you. Jorge

[R1200CL]

11 hours ago, Tokyokyoto said:

I have the $99.00 clock but not sure hat wave or impedance.  It does have 50 ohm taps though.

Judging from that picture you’re doing a lot of clocking 😀

 

You may test out remove one or two clock cable, based on the idea of isolation. 

[R1200CL]

Not sure if right time or tread, but by accident I just came across this very old post. 

I suppose some of it has been covered by previous white paper, but I suppose there are more things that can be shown or told about these effects of a jitter / phase noise marker the next coming 2 to 5 year.  Part of this of cause what the fantastic EtherRegen is all about and why we all love it. I would expect the effect of external clocks can be measured. And in both directions. Rember the B>A effect was said might not be as good as A>B. Would be interesting to know. 

“John will prove--by evidence of the marker at the analog output of the DAC downstream--that the phase-noise fingerprint of upstream interfaces can have a measurable influence on the analog output.”

I had to do some changes and error search in my setup yesterday. I really don’t need those fingerprints to be convinced 😀

System with and without the EtherRegen was different. Now my second, but first clock from Adrian has been ordered. I couldn’t afford what I wanted. So I go with the King. After all there is already a queen at home 😉

 

 

[soares]

Unbelievable it’s what comes to

my mind.  I never imagine that such a device could improve so much the reality of what I am hearing. Thank you John and Alex for the tip. Details, timbres and all the rest are there in spades. I must say that I ordered the 50 ohms version as the 75 was not available and it fits the Chinese 75 ohms clock.

Just for reference I share with you my setup:

Router>Rj45>oM>SFP>
Buffalo2016>SFP>oM>Rj45>Zen Mkiii>Rj45> Delock 62619>Rj45>eR  (+ MC)>SFP>oR>USB>iR
USB>Phoenix>USB>
DAC.

Cheers Jorge

[agladstone]

20 minutes ago, soares said:

Unbelievable it’s what comes to

my mind.  I never imagine that such a device could improve so much the reality of what I am hearing. Thank you John and Alex for the tip. Details, timbres and all the rest are there in spades. I must say that I ordered the 50 ohms version as the 75 was not available and it fits the Chinese 75 ohms clock.

Just for reference I share with you my setup:

Router>Rj45>oM>SFP>
Buffalo2016>SFP>oM>Rj45>Zen Mkiii>Rj45> Delock 62619>Rj45>eR  (+ MC)>SFP>oR>USB>iR
USB>Phoenix>USB>
DAC.

Cheers Jorge

Nice and simple 😂

..... I’m sure it sounds amazing!! 

[soares]

13 minutes ago, agladstone said:

Nice and simple 😂

..... I’m sure it sounds amazing!! 

To be honest, I never heard such a good SQ in my whole life... 

However it’s a little bit complicated with the other members of the family...😂

[agladstone]

@soares

Love it!!! The back of my rack looks even worse!! 
mom finding it more and more challenging trying to find space for all my little gizmos and then the associated power supply for each one of the gizmos! 
Like your set up, I also have been making all sorts of homemade foam and rubber and wood blocks etc to hold or balance them all and the cables are all heavier and stronger than the little gizmos, so yet another issue :) 

I think it’s about time that Uptone comes out with a special rack to hold all these things 😉

 

[MasterWarzombie]

2 hours ago, soares said:

To be honest, I never heard such a good SQ in my whole life... 

However it’s a little bit complicated with the other members of the family...😂

it is the jungle.

[MasterWarzombie]

19 hours ago, R1200CL said:

Not sure if right time or tread, but by accident I just came across this very old post. 

I suppose some of it has been covered by previous white paper, but I suppose there are more things that can be shown or told about these effects of a jitter / phase noise marker the next coming 2 to 5 year.  Part of this of cause what the fantastic EtherRegen is all about and why we all love it. I would expect the effect of external clocks can be measured. And in both directions. Rember the B>A effect was said might not be as good as A>B. Would be interesting to know. 

“John will prove--by evidence of the marker at the analog output of the DAC downstream--that the phase-noise fingerprint of upstream interfaces can have a measurable influence on the analog output.”

I had to do some changes and error search in my setup yesterday. I really don’t need those fingerprints to be convinced 😀

System with and without the EtherRegen was different. Now my second, but first clock from Adrian has been ordered. I couldn’t afford what I wanted. So I go with the King. After all there is already a queen at home 😉

 

 

 Rember the B>A effect was said might not be as good as A>B. Would be interesting to know?

 

can you clarify this point?

[R1200CL]

5 hours ago, MasterWarzombie said:

can you clarify this point?

 

So we don’t know how good phase numbers is needed if B to A is utilized. 
 

[R1200CL]

@JohnSwenson

Do you think changing some parameters in the EtherRegen SW can be beneficial when using an external 10 MHz clock ?

 

”Oh, one other cool thing:

We've been going over and over how the programming of the Ethernet switch chip (its actually a part capable of being a fully managed switch be we are not running it that way; just a bunch of other key interface registers have to be set) and the clock synthesizer will be handled.  Because the synthesizer has to have a whole different set of parameters if someone decides to use an external 10MHz clock as its reference (instead of the nice Crystek CCHD-575 internal), we can't just program the synth timings and frequencies once here at our offices.  So both the switch chip and the clock synth will each have their own tiny microprocessor (which we will first flash here during production) and which will program their respective parts each time power is applied the EtherREGEN.  The couple of things I think are cool are:

1) the microprocessors turn off completely after they load their code to their assigned chips (so no noise or power draw from them);

2) for the Ethernet switch chip, there will be a vertical microUSB port on the board, and in the eventuality that later on we discover a needed or desired code change, we can make a file available on the web.  And John worked with Adafruit to figure out code such that plugging the USB cable will turn on the boot-loader, make a pseudo drive appear on the computer desktop, and when the updated code file is dragged to it the code will automatically load and be stored in the EtherREGEN.  We think this is really simple and elegant!”

[Superdad]

2 hours ago, R1200CL said:

Do you think changing some parameters in the EtherRegen SW can be beneficial when using an external 10 MHz clock ?

No. None at all.  The clock synthesizer already receives correct and optimized programming code for a 10MHz clock when the EtherREGEN is set to run from an external clock.

Other than being more precisely referenced, the 4 differential clock output lines from the synthesizer (two at 25MHz and two at 250MHz to run our special reclocking flops) are exactly the same as far as the rest of the functioning of the switch goes. Nothing to change.