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3 hours ago, Qstik said:

Sorry Alex and John - that statement does not correlate with my listening experience, nor can I find any supporting references in Google searches.  Sine wave impedance mismatches will cause reflections at the sine wave frequency while square wave impedance mismatches will cause reflections at the fundamental square wave frequency + higher harmonics of the fundamental square wave frequency.  I also fail to understand why a 10 MHz sine wave benefits from an 11 MHz low pass filter, unless there is considerable noise on the sine wave.  However, if a DAC, for instance, is expecting a 10 MHz sine wave external clock signal and only a square wave clock signal is available, that an 11 MHz low pass filter might filter a square wave to a passable sine wave.  Please enlighten me.

Lets tackle the impedance issue first. The problem with reflections occur at the receiver threshold detector, if the reflection comes back to the receiver and is near in time to the original it can cause the detector to give erroneous edges, or jitter to the detected edge. As you mention the sine waves do get reflected as well,  but at 10MHz the wave length is long enough that a reflection causing disruption will take either a very long or very short cable. With a square wave the harmonics have shorter wavelengths making it much more probable the reflection may cause a detrimental effect on the receiver.

The issue of shielding, filters etc is a bit more complicated. It has to with the "steepness" of the transition, the ramp time. A square wave has a very fast transition, a sine wave a very slow transition. When noise is overlayed on top of the signal, lets say from noise picked up by the cable, the result on the receiver is very different for a slow vs fast transition. Lets use some actual number here to make it easier to understand. Lets say we are using a receiver that has a threshold of 2V, below 2V the receiver interprets that as "low" above 2V it sees a "high". Lets say that there is 10mv of noise overlayed on the signal, the signal is now 2.01V, it will reach the 2.0V threshold slightly earlier, the square wave (with 1ns per volt ramp) sees a 10ps change in where the threshold crossing happens, but with a sinewave of 100ns per volt ramp that same noise causes 1000ps (or 1ns) of change in where the receiver sees the transition. Thus the same noise produces a huge difference in timing change at the receiver. The result is that sine wave signals need hugely better shielding than square wave signals. The filter at the receiver helps to filter out noise that makes it through the shielding.

With a squarewave the most important property is wide bandwidth, attenuation of the harmonics decrease the ramptime allowing noise to create greater timing changes in the receiver. Because of fast ramp times extremely good shielding is not as important. For a sinewave, which only has one frequency, wide bandwidth is not important at all, but shielding is extremely important.

John S.

2 hours ago, Qstik said:

1.  By saying that a DAC "expected" a sine or square wave clock signal I meant that its clock receiving PLL circuit was designed, optimized and/or worked best with either sine or square wave signals.

Sorry, but it just does not work that way.

Here is a primer post of John's that may be helpful:

2 hours ago, Qstik said:

2.  I can understand that a square wave clock signal with a very sharp rise time might be best for minimizing the effects of ground plane noise while a sine wave clock signal might be best for minimizing time domain jitter.  Put another way to John's point, sine wave clock signals tend to be worse for ground plane noise sensitivity.

That's conflating a bunch of complex concepts!  You might do well to reread our paper on the subject:

Considerations regarding 10MHz external reference clocks...

2 hours ago, Qstik said:

But my question to John is why wouldn't a 10 MHz bandpass filter be best for 10 MHz sine clock signals?  I would expect ground plane noise to be possible above and below the clock frequency.

I think because the characteristics of the filter itself are best kept away from the signal you are trying to pass.

2 hours ago, Qstik said:

3.  Google tells me that the wavelength of a 10 MHz electrical signal is 98.36 ft.  Since the cable I ordered from BJC is two feet in length; it is very nearly an integer ratio of 50:1.  This is probably bad from a reflection standpoint.  I may just order a 3 foot length of the same Belden 4794R SDI cable to try as an experiment.

Honestly this discussion of cables and outputs--especially since you are using sine wave clocks and not a Mutec (square wave) which is the topic of this thread--belongs in the other big thread on clocking and the EtherREGEN.  [I might move over to there all these posts.]

Thanks for you enthusiasm for the subject Mike.  

BTW, I'm happy to report that REF10 Nanos are selling well for us. Been getting a new shipment in nearly every week and it seems that so far UpTone has sold more REF10 Nanos than any other USA-based firm.  And that's without ANY advertising! 

3 hours ago, Qstik said:

Alex,

 

 

 

2.  I can understand that a square wave clock signal with a very sharp rise time might be best for minimizing the effects of ground plane noise while a sine wave clock signal might be best for minimizing time domain jitter.  Put another way to John's point, sine wave clock signals tend to be worse for ground plane noise sensitivity.  But my question to John is why wouldn't a 10 MHz bandpass filter be best for 10 MHz sine clock signals?  I would expect ground plane noise to be possible above and below the clock frequency.

 

 

I'm not talking about ground plane noise here, I'm talking about noise picked up "through the air" by the cable itself. Even if you had significant leakage current running through the clock cable, a filter wouldn't do any good because leakage current is common mode, it is the same on the ground AND signal conductors, a filter works on the difference between the ground and signal, if they are the same a filter has nothing to work on.

The length issue is only applicable IF you have an impedance mismatch and you are running a square wave. With a sine wave with an impedance mismatch the only length issue is being too short. Exactly how short is very much determined by the receiver circuit so there is no way to generalize. My guess is that 2 feet and up is probably fine in most cases, between 1ft and 2ft may or may not be fine, and probably a good idea to not go below 1 ft. If everything is properly impedance matched there is no length issue at all.

John S.

15 hours ago, Schafheide said:

...but my concern (in leaving it on 24/7) is the life of the electrolytics (this, of course, also applies to the LPS).

Your thoughts?

There is likely much more stress on components from power on/off cycles--and heat/cool cycles--than from continuous use. Quality aluminum electrolytic capacitors will last decades.  I have power amps that are more than 40 years old and have rarely been powered off.  Still perfectly fine.  

Your Mutec clock is likely to outlive you. 

Update time from across the pond, hope all you chaps are well this week.

The Nano does take a while to FULLY deliver its true potential, just leave the clock switched on it will NOT harm the unit, as John has mentioned, I have two Wadia's that were left on for close to 26 years with zero issues other than natural electrical cap degrading.

Its obvious when you first switch on the spatial information is more correct and those cues in the music you didn't realise were there or were hidden in the programme are now evident. Music just makes more ‘sense'

Low frequency response with also improve with better definition/timing and depth, although this is one of the last traits to fully develop imho.

One of our demo units have been returned from a reviewer, I did measure it before it went away and again yesterday subtle difference in the measurements BUT large differences in the sound quality.

Two weeks minimum being actually on would be my suggestion, one of our units has 1500 hours now and sounding very nice indeed.

Is using a quality power supply worth the extra? unequivocally YES

Thus far we have tested over 16 aftermarket and DIY constructed LPS and not one has failed to improve the Nano

It’s also a great size and easy to use, very pleased with Mutec’ s latest offering and I’m sure that you will be 100% as well. Alex is your man this side of the pond, great chap, great products

"Depends upon your system application and needs, but the performance and refinement of the big REF10 is hard to beat—especially at the new lower price (for years it was $5K). 
Call or write if you would like one. Can ship right away. "

I received  the Nano about 2 weeks ago. I have a mid-fi system. We stepped out of the audiophile world for about 10 years and wanted to get back into audio.  It is shocking what streaming audio can do now. In my recent experience,  pretty damn/darn good through Tidal (I also use Amazon through a WIIM PRO) . Current setup is  running from a Spectrum router/switch>> TP link optical converter>>AOC cable>> Etherregen via optical in.

B side of output via ethernet cable >> Integrated amp (Lyghdorf TDAI-3400).

The Etherregen is connected to the Mutec Mano VIA a Belden Cable from Custom Cables. I think they are in TX. The cable model may be  a 4694R or something like that. It is pretty flexible and I think Alex told me it would work ok at shorter distances, which it does. 

I am shocked by the improvement. I know that my speakers are the limiting factor.  I had the opportunity to hear everything from the Magico Q series to the Vivid Giyas, Hartbeth, Spendor, blah blah blah. . I am basing my review of very mid-fi speakers: Sonus Faber Olympia I. I am running 2 subs with the  system to help out with the lower frequencies. 

I am going to try to explain the difference the Nano made AFTER the Etherrengen was in place. The Etherregen made a a great difference and I am very thankful for having found it.

There is no magic in this crap. We are just moving along digital information. This is just simple 1 and 0, to the damn horse. How we integrate them is way above my pay level. The difference in my very modest system, race for the triple crown. The listening difference, It MADE me go into work one hour late. I had to listen just a little bit longer, hence the reason for me being one hour late to work. The combintaiton MADE listen to more. 

In all reality, I was just lookin for a reason not to go to work. All kidding aside, you will hear details that not hear before, subtle crap, like pitch, intonation, stuff that like in voices. Bass, more pitch and control. The biggest thing that I hear: silk, continuity, coherence and naturalness. I hope you all enjoy the world of digital as much as I do. I am still keeping my vinyl for for a rainy day, but this is fun as can be.