Master Clock for your EtherREGEN

[Avalfa]

3 hours ago, R1200CL said:

Not sure how you’re powering the clock, but if possible a better DC cable won’t hurt. 

That's next on the list. Both ER and clock are now powered by the smps's that came with them.

[lwr]

1 hour ago, Avalfa said:

That's next on the list. Both ER and clock are now powered by the smps's that came with them.

Having both ER and clock now powered by the smps's that came with them is a definite bottleneck in your system.  Of course there are some who find it worthwhile to use LPS's that cost much more than the ER itself, but you need put off buying an inexpensive LPS to use until you can afford the ultimate LPS. 

 

Some smps's are better than others.  The smps that comes with the ER is actually far better than most, but the one that comes with the Chinese repurposed cell tower clock is not.  That's the first one to replace IMHO.  Replacing both smp's with decent quality LPS's will make a quite noticeable uptick in SQ, even if you use quite inexpensive ones. YMMV

 

[lwr]

correction: ... you needn't put off ...

[MartinT]

The clock needs good power (I use an LPSU), a good DC cable (Coherent), vibration control (Black Ravioli Pads, titanium block glued to OCXO, granite mat on top), good clock cables (Canare LV-77S) and a lot of warm-up time.

[Avalfa]

I will try in the near future.

The clock cable I used will be sufficient and is good quality, maybe I will try other ones In the future.

 

I'm planning on building a LPS  with ultra capacitors for the ER.

And a proper star-quad+shielded DC cable for the ER.

I have a proper smps 12 v DC  which I will try next week on the clock.

 

Vibration control is done here. 

[R1200CL]

On 9/29/2020 at 1:25 AM, Superdad said:

Still, all are months away and it is too soon for any bean spilling.

Any Xmas updates maybe ? 🤶🏻

[panhead]

On 11/16/2020 at 5:42 AM, R1200CL said:

This is the seller one should purchase from. 
 

https://www.aliexpress.com/item/4001245799329.html?spm=a2g0s.9042311.0.0.367a4c4dhrWEwV

 

@panhead

Your link has only one square wave output. It’s not the same as rest of us bought. (But will work). 

You were right!    Ordered from hamshop at the link and it arrived a couple of days ago.     It has the proper 75 ohm connector.    The ebay seller had 50 ohm.    Ive also swapped to the Geist  Apogee Wyde eye cable which is better than previous.

 

A big thank you!

[Avalfa]

Just now I tried a very short experiment, with a  for this experiment put together battery power supply 12.7V DC.

 

It was short because even while I paired 2x 9v battery together parallel and two big 1.5v 's in series behind it, it dropped in voltage quickly think about 2-3 songs before it went below 10.7 V that's where I stopped. since stable 12V is supposed to be best. I didn't want to push it.

 

However, indeed straight away noticeable more details. PRaT even enhanced in a way I didn't think was possible here.

 

So yes I agree on the better power supply on the clock.

Last days I have been reading through some older topics also. It makes more sense to me now. Since the BNC is at the clean b -side where you just don't want any cheap smps with all its noise etc. interfering with the clean signal.

 

For now aiming on a lps1.2 from uptone, I will order one in the nearby future (from vortexbox in the U.K.) or perhaps build one.

Since I have already got plans to build a proper ultra caps LPS at 10V to power the ER. Would be nicest if I can put it all together in one housing since I just hate all the loose small equipment pieces, and now there just getting more 😂.

 

 

 

[Roasty]

https://www.ebay.com/itm/10MHz-Reference-OCXO-Frequency-Standard-Sine-Wave-Square-Wave-For-EtherREGEN/284044913347?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

Is there any issue with ordering this one? Other than the 1 square 2 sine wave outputs. Have just messaged the seller to ask if it is 50ohm or 75ohm. 

 

I've no experience with using external clocks, so just gg to experiment with the ER first, and if it's a good improvement, I may send my sotm streamer in to get a clock input installed. 

 

By the way, has anyone tried the Paul Pang clock? 

[Roasty]

Reason I asked about the square or sine wave, is because if I get the sotm modded for a clock input, I assume it would like a sine wave since their own sotm clock outputs as a sine wave (?). 

[R1200CL]

9 hours ago, Roasty said:

Is there any issue with ordering this one?

Please purchase the link previously suggested on Aliexpress.

 

Is there any reason not to ?

 

Edit

Are you sure SoTM is using sinus ?

[Roasty]

17 minutes ago, R1200CL said:

Please purchase the link previously suggested on Aliexpress.

 

Is there any reason not to ?

 

Edit

Are you sure SoTM is using sinus ?

 

From sotm site :

 

Frequency : 10.000MHz sine wave
  Output level : 13dBm(2.825Vp-p@50Ω), ±2dBm
  All isolated clock output
  Output connector
    50Ω BNC connector x 4
    Optional 75Ω BNC connector available

[Superdad]

15 hours ago, Roasty said:

Reason I asked about the square or sine wave, is because if I get the sotm modded for a clock input, I assume it would like a sine wave since their own sotm clock outputs as a sine wave (?). 

Maybe @JohnSwenson will weigh in on this with more accurate and authoritative knowledge than I.

As I understand it, most all digital audio and computer devices prefer a clock which is a square wave—I think because easier and more accurate to trigger at a given voltage transition level.  I recall that sine wave clocks are mostly used in GPS, ham radio, and test equipment systems.

But producing a really good square wave from a clock is harder—at a minimum requiring extra sine>square converter circuitry which, if not done well will reduce the measured phase-noise performance.

[It can be noted that the very fine Mutec REF10 outputs a square wave—and this is one aspect that makes it a superior device.]
 

I find it confusing that some reference clock makers in the audio space are offering only sine wave output when most all the devices they are being used with work better from a square wave.  Even SOtM’s own streamer would be better fed a square wave as I do not think it has a internal sine>square circuit.  I could be wrong on this last point with regards to SOtM. As with any device which accepts an external 10MHz reference clock (but whose chips run at some other frequency), the SOtM units have a clock synthesizer chip, and while those may perform better with a square wave input than with sine, they will in most all cases be outputting a square wave for the chips they are feeding.

One last oddity in regards the SOtM Ultra models (of smS-200 streamer, tX-USB hub, and sNH-10G switch) is that they all include SOtM’s older giant sCLK-EX board, which, when fully populated can be programmed to output four separate frequencies, yet the products they build it into (for $700 premium) are using only one clock line from it—via a rather long coax cable. 
[In contrast, the EtherREGEN uses a much newer version of SiLabs clock synthesizer, positioned right next to both the BNC jack and the Crystek CCHD-575 (for when internal XO is used as reference), and we use all four differential outputs of the chip (two lines at 250MHz for our special ultra-low-jitter differential flip-flops on each side of the A>B moat, and two lines at 25MHz for the Ethernet chips on each side of the moat).]
 

[JohnSwenson]

OK, here goes a bit of a primer on clocks, clock transmission and digital audio.

 

First the use: digital circuits require square wave clock signals. If fed a sine wave the signal would have a very slow ramp at the threshold that noise on the wire would produce large amounts of jitter, so much so that in many circumstances the circuit would not work AT ALL.

 

BUT square waves are hard to send long distances over wires. If you look at the specs for coax cables you will find that the attenuation through the cable increases as the frequency goes up, otherwise known as a low pass filter. Putting a square wave through this attempts to convert it into a sine wave. The longer the cable the more like a sine wave it looks at the other end. This is why all traditional clock distribution networks use sine waves. It takes very expensive cable to keep a square wave square over long distances. Over short distances (say a few feet) this effect is very small.

 

The reason most "master clocks" you find out there use sine waves is they were designed to drive large distribution networks where a sine wave was the only way to do it.

 

If you send a sine wave into a digital audio device, there has to be something that converts the sine wave into a square wave for use by the digital circuits. ALL such circuits add some jitter to the clock signal in doing this conversion, some circuits a lot, some a little and some a VERY little amount. There are three common ways to do this:

 

Comparitors are cheap and easy, but because they are essentially very high gain amplifiers, they also amplify the noise on the sine wave, increasing jitter by a large amount.

 

Cheap digital inverters are also frequently used, these do quite a good job actually: because they are not very fast they tend to limit the high frequency noise thus add quite a bit less jitter.

 

The best way is a multi-stage low gain amplifier with a filter between stages designed to just amplify the specific frequency. This gets rid of almost all of the noise which results in a VERY small amount of jitter added to the signal. It should be obvious that this is neither cheap nor easy, thus very rarely done.

 

When dealing with a clock synthesizer (such as in the ER and SOtM products), things are a little different, you are not directly converting the sine wave into a square wave. The input is used as a reference signal of a PLL. You can use either a sine or square, but will get different performance depending on how the PLL was designed. In the case of the Silicon Labs synthesizers they were specifically designed for a square wave reference, they WILL work with a sine wave, but the jitter on the output will be lower with a square wave.

 

We designed the EtherREGEN making the assumption that the user will have the "master clock" a few feet away rather than hundreds of feet away. In this configuration it is better to assume a square wave going directly into a clock synthesizer. If we had decided to assume a sine wave the extra circuitry would have degraded the signal if you fed it a square wave. Thus for a master clock a short distance away the best result is obtained with a square wave going directly into the synthesizer.  It is also way cheaper, and saved months off the development time.

 

John S.

[Roasty]

@JohnSwenson

 

Thank you for that brief but to the point masterclass! I'm sure a lot of people appreciated that informative post. I know I did! 

[manueljenkin]

1 hour ago, JohnSwenson said:

OK, here goes a bit of a primer on clocks, clock transmission and digital audio.

 

First the use: digital circuits require square wave clock signals. If fed a sine wave the signal would have a very slow ramp at the threshold that noise on the wire would produce large amounts of jitter, so much so that in many circumstances the circuit would not work AT ALL.

 

BUT square waves are hard to send long distances over wires. If you look at the specs for coax cables you will find that the attenuation through the cable increases as the frequency goes up, otherwise known as a low pass filter. Putting a square wave through this attempts to convert it into a sine wave. The longer the cable the more like a sine wave it looks at the other end. This is why all traditional clock distribution networks use sine waves. It takes very expensive cable to keep a square wave square over long distances. Over short distances (say a few feet) this effect is very small.

 

The reason most "master clocks" you find out there use sine waves is they were designed to drive large distribution networks where a sine wave was the only way to do it.

 

If you send a sine wave into a digital audio device, there has to be something that converts the sine wave into a square wave for use by the digital circuits. ALL such circuits add some jitter to the clock signal in doing this conversion, some circuits a lot, some a little and some a VERY little amount. There are three common ways to do this:

 

Comparitors are cheap and easy, but because they are essentially very high gain amplifiers, they also amplify the noise on the sine wave, increasing jitter by a large amount.

 

Cheap digital inverters are also frequently used, these do quite a good job actually: because they are not very fast they tend to limit the high frequency noise thus add quite a bit less jitter.

 

The best way is a multi-stage low gain amplifier with a filter between stages designed to just amplify the specific frequency. This gets rid of almost all of the noise which results in a VERY small amount of jitter added to the signal. It should be obvious that this is neither cheap nor easy, thus very rarely done.

 

When dealing with a clock synthesizer (such as in the ER and SOtM products), things are a little different, you are not directly converting the sine wave into a square wave. The input is used as a reference signal of a PLL. You can use either a sine or square, but will get different performance depending on how the PLL was designed. In the case of the Silicon Labs synthesizers they were specifically designed for a square wave reference, they WILL work with a sine wave, but the jitter on the output will be lower with a square wave.

 

We designed the EtherREGEN making the assumption that the user will have the "master clock" a few feet away rather than hundreds of feet away. In this configuration it is better to assume a square wave going directly into a clock synthesizer. If we had decided to assume a sine wave the extra circuitry would have degraded the signal if you fed it a square wave. Thus for a master clock a short distance away the best result is obtained with a square wave going directly into the synthesizer.  It is also way cheaper, and saved months off the development time.

 

John S.

Regarding the analog design, is it like the inverse of notch filters at the fundamental and harmonics of the square wave to be obtained?

 

What are the recommended cabling/signal routing choices for this approach? Do we have a litz or uspcb equivalent for this connection for both better hf performance and lower spurious noise.

 

The hf roll off issue is because of skin effect which is because of eddy currents which is because of electromagnetism (governed by Maxwell's laws) which is because nature just seems to work that way right? (Apart from self inductance, and line-to-line or line to ground inductance or capacitance too).

[GS6]

Having seen the big sonic boost provided by 1st the external clock, second the tungsten block, 3rd an isolation platform, and 4th making a 20cm clock cable from solid silver Oyaide 75ohm cable and solid silver Oyaide 75ohm BNC connectors, I'm waiting on my Longdog Audio LPS arriving, which I'm sure will give another big uptake. Thanks for all the advice everyone has given here; i'm a year or so down the rabbit hole of the hobby, and still very much learning on the technical side.

 

With that in mind, if my clock-fed EtherRegen is feeding my UltraRendu a very good signal, and the UltraRendu is feeding my DAC over only 0.5m on a good USB cable, will a device that reclocks the signal again (like an iFi iPower USB or an ISORegen) do more harm than good?

 

(This is not an X brand vs Y brand question, it is about me trying to understand the clocking concept more generally). 

 

Thanks in advance all!

 

[MartinT]

I can only speak from my own experience. I reclock ethernet with the ER and then reclock the USB from my ultraRendu again with a Mutec MC-3. Both ER and Mutec are fed with 10MHz from my OCXO master clock. Does reclocking twice work? It certainly works for me, giving incredible detail and insight from my LKS DAC and analogue-like soundstage and note decay.

 

Nick Gorham's Longdog PSU will give you great performance for sure.

[FIndingit]

Now we only need somebody to look at the Chinese ocxo boards and say whether the square wave implementation looks good or bad.
 

I don’t think there is any isolation of the signal, which the expensive ones have. 

[Pro Jules]

Mutec Master clock REF10 SE120 sounded heavenly in my recent trials. Turned horizontal left / right into a glorious 3D hemisphere of reverb depth and HEIGHT. 
 

clock experiments - definitely worth trying to hear for yourself. 

[JohnSwenson]

21 hours ago, manueljenkin said:

Regarding the analog design, is it like the inverse of notch filters at the fundamental and harmonics of the square wave to be obtained?

 

What are the recommended cabling/signal routing choices for this approach? Do we have a litz or uspcb equivalent for this connection for both better hf performance and lower spurious noise.

 

The hf roll off issue is because of skin effect which is because of eddy currents which is because of electromagnetism (governed by Maxwell's laws) which is because nature just seems to work that way right? (Apart from self inductance, and line-to-line or line to ground inductance or capacitance too).

The type of filter used in the multistage squarers are classed as bandpass, they let a narrow range of frequencies pass through without attenuation but attenuate everything else.

 

The HF roll-off of the cables is actually primarily due to the dielectric used and the size of the cable. This means that the lowest roll-off cables are large diameter and stiff (they use teflon). Thin flexible cables have high attenuation at high frequencies.

 

My analysis of the cable situation shows that probably the best square wave clock cables would be custom flat cables. There are some extremely good high frequency dielectrics available for flat cables. Unfortunately they are very expensive and the NRE charges for implementing such a cable are very high.

 

John S.

[manueljenkin]

Thank you very much John. Is there any possibility of mitigating some of the cable limitations by using a carefully designed PCB (controlled parasitics) instead of a wire?

 

Curious about this because the uspcb sounds much better than any cable at similar price to me. The causation I guess is different though, the latter being more due to better ground plane right?

[R1200CL]

11 hours ago, FIndingit said:

Now we only need somebody to look at the Chinese ocxo boards and say whether the square wave implementation looks good or bad.
 

I don’t think there is any isolation of the signal, which the expensive ones have. 

I think @JohnSwenson is supposed to have one, if Alex has sent his over for evaluation. 
I guess not a prioritized task 😀

[JohnSwenson]

2 hours ago, manueljenkin said:

Thank you very much John. Is there any possibility of mitigating some of the cable limitations by using a carefully designed PCB (controlled parasitics) instead of a wire?

 

Curious about this because the uspcb sounds much better than any cable at similar price to me. The causation I guess is different though, the latter being more due to better ground plane right?

What I mentioned above ARE PCBs, to be precise flexible multilayer PCBs using very high quality thin flexible dielectrics between copper layers. With multi layers they can be shielded very well and have very high precision impedance control. They just cost a lot of money.

 

Back in my days as a custom chip designer we used such cables for very high speed connections between boards, they cost in the range of $900 to $1400 per cable and were about 7 inches long. Not exactly cheap cables.

 

John S.

[JohnSwenson]

34 minutes ago, R1200CL said:

I think @JohnSwenson is supposed to have one, if Alex has sent his over for evaluation. 
I guess not a prioritized task 😀

I have not received anything yet.

 

John S.