Mutec REF 10 Masterclock

[rickca]

26 minutes ago, romaz said:

While it appears Sonore has not yet substantiated the impact of clocking in these "spaghetti" devices, I would encourage you guys to give it a go.  Where there's smoke, there's usually fire, and so I believe you will find that the many who have gone down this path are not just listening to placebo.

When someone comes up with a better integrated solution ... let's call it a meatball ... maybe we won't need as much spaghetti to satisfy our appetite for enhanced sound quality.

[austinpop]

1 minute ago, rickca said:

When someone comes up with a better integrated solution ... let's call it a meatball ... maybe we won't need as much spaghetti to satisfy our appetite for enhanced sound quality.

 

Bravo!  

[rickca]

8 hours ago, julian.david said:

Hope this helps!

Thank you, Julian.  I'm very impressed with the attention to detail in every aspect of engineering in the REF 10.  There are just some functional things in both the REF 10 and the Mutec MC-3+ Smart Clock USB that are overkill for those of us who are more prosumer than pro.

[romaz]

11 minutes ago, barrows said:

This is a exactly what John S. is doing.  Hopefully his research will be able to determine the mechanism for any improvements, and then audiophiles can move forward in an informed way.  Of course we are well aware of the value of a better clock in our Ethernet Renderers, we first started experimenting with that long ago, which led to the development (among other things) of the ultraRendu and Signature Rendu SE.

But, if I am going to use clocks as accurate as the Mutec claims to be, they are going in my DAC first as a replacement for the audio clock(s) where they can do the most good.  Of course audio clock frequencies will not have as low phase at low frequencies as a 10 MHz clock can (phase noise scales with clock frequency all other things remaining equal) but using a fixed frequency clock at audio frequency will perform better than a 10 MHz reference clock used to generate (digitally) audio frequency clocks.  There are now some pretty nice audio frequency clocks available at semi-reasonable prices.

 

This is what is so challenging with digital audio.  No one truly understands it all.  What I respect about people like John Swenson and Rob Watts is that they fully acknowledge this and that some phenomena are inexplicable but just because certain observations are inexplicable, does't make them invalid.  Look how routinely Sonore and Uptone Audio get bashed on ASR based on lack of measurements.  It seems some people, purely based on theories or measurements, already know how somethings sounds even before the needle hits the groove.

 

With regards to the clock in a DAC, this appears to be a very complex topic and more than I am willing to tackle with my DAVE.  Here is what Rob Watts has to say:

 

"The issue of clocks is actually very complex, way more of a problem then in simply installing femto clocks. People always want a simple answer to problems even if the problem is multi-dimensional and complex. I will give you a some examples of the complexities of this issue.

 

Some years back a femto clock became available, and I was very excited about using it as it had a third of the cycle to cycle jitter of the crystal oscillators we were using. So I plugged it in, and listened to it. Unexpectedly, it sounded brighter and harder - completely the opposite of all the times I have listened to lower jitter. When you lower jitter levels in the master clock, it sounds smoother and warmer and more natural.

 

So I did some careful measurements, and I could see some problems.

 

The noise floor was OK, the same as before, and all the usual measurements were the same. But you could see more fringing on the fundamental, and this was quite apparent. Now when you do a FFT of say a 1 kHz sine wave, in an ideal world you would see the tone at 1 kHz and each frequency bucket away the output would be the systems noise floor. That is, you get a sharp single line representing the tone. But with a real FFT, you get smearing of the tone, and this is due to the windowing function employed by the FFT and jitter problems within the ADC, so instead of a single line you get a number of lines with the edges tailing of into the noise. This is known as side lobes or fringing. Now one normally calibrates the FFT and the instrument so you know what the ideal should be. Now with a DAC that has low frequency jitter, you get more fringing. Now I have spent many years on jitter and eliminating the effects of it on sound quality, and I know that fringing is highly audible, as I have done many listening tests on it. What is curious, is that it sounds exactly like noise floor modulation - so reduce fringing is the same as reducing noise floor modulation - they both subjectively sound smoother and darker with less edge and hardness.

 

So a clock that had lower cycle to cycle jitter actually had much worse low frequency jitter, and it was the low frequency jitter that was causing the problem and this had serious sound quality consequences. So a simple headline statement of low jitter is meaningless. But actually the problem is very much more complex than this.

 

What is poorly understood is that DAC architectures can tolerate vastly different levels of master clock jitter, and this is way more important than the headline oscillator jitter number. I will give you a few examples:

 

1. DAC structure makes a big difference. I had a silicon chip design I was working on some years back. When you determine the jitter sensitivity you can specify this - so I get a number of incoming jitter, and a number for the OP THD and noise that is needed. So initially we were working with 4pS jitter, and 120dB THD and noise. No problem, the architecture met this requirement as you can create models to run simulations to show what the jitter will do - and you can run the model so onlyjitter is changed, nothing else. But then the requirements got changed to 15 pS jitter. Again, no problem, I simply redesigned the DAC and then achieved these numbers. So its easy to change the sensitivity by a factor of 4 just by design of the DAC itself - something that audio designers using chips can't do.

 

2. DAC type has a profound effect on performance. The most sensitive is regular DSD or PDM, where jitter is modulation dependent, and you get pattern noise from the noise shaper degrading the output noise, plus distortion from jitter. R2R DAC's are very sensitive as they create noise floor modulation from jitter proportionate to the rate of change of signal (plus other problems due to the slow speed of switching elements). I was very concerned about these issues, and its one reason I invented pulse array, as the benefit of pulse array is that the error from jitter is only a fixed noise (using random jitter source with no low frequency problems). Now a fixed noise is subjectively unimportant - it does not interfere with the brains ability to decode music. Its when errors are signal dependent that the problems of perception start, and with pulse array I only get a fixed noise - and I know this for a fact due to simulation and measurements.

 

3. The DAC degrades clock jitter. What is not appreciated is that master clock jitter is only the start of the problem. When a clock goes through logic elements, (buffers level shifters, clock trees gates and flip-flops plus problem of induced noise) every stage adds more jitter. As a rough rule of thumb a logic element adds 1 pS of more jitter. So a clock input of 1pS will degrade through the device to be effectively 4 pS once it has gone through these elements (this was the number from a device I worked on some years ago). So its the actual jitter on the DAC active elements that is important not the clock starting jitter.

 

The benefit I have with Pulse Array is that the jitter has no sound quality degrading consequences - unlike all other architectures - as it creates no distortion or noise floor modulation. Because the clock is very close to the active elements (only one logic level away), the jitter degradation is minimal and there are no skirting issues at all. This has been confirmed with simulation and measurement - its a fixed noise, and by eliminating the clock jitter (I have a special way of doing this) noise only improves by a negligible 0.5 dB (127 dB to 127.5 dB).

 

This is true of all pulse array DAC's even the simpler 4e ones. In short the jitter problem was solved many years ago, but I don't bleat on about it as its not an issue and because it's way too complex a subject to easily discuss.

 

Pulse Array is a constant switching scheme - that is it always switches at exactly the same rate irrespective of the data, unlike DSD, R2R, or current source DAC's. This means that errors due to switching activity and jitter are not signal dependent, and so is innately immune from jitter creating distortion and noise floor modulation and any other signal related errors. The only other DAC that is constant switching activity is switched capacitor topology, but this has gain proportionate to absolute clock frequency - so it still has clock problems.

 

I plan to publish more detailed analysis of this, but from memory all of my DAC's have a negligible 0.5dB degradation due to master clock jitter, so its a non issue.

 

And yes you are correct, the absolute frequency is quite unimportant, so forget oven clocks, atomic clocks etc. Also the clock must be physically close to the active elements,with dedicated stripline PCB routing with proper termination. Running the clock externally is a crazy thing to do, as you are simply adding more jitter and noise and an extra PLL in the system."

[vortecjr]

1 hour ago, romaz said:

While it appears Sonore has not yet substantiated the impact of clocking in these "spaghetti" devices, I would encourage you guys to give it a go.  Where there's smoke, there's usually fire, and so I believe you will find that the many who have gone down this path are not just listening to placebo.

Barrows has already touched on what is taking place behind the scenes with John. While he is doing this on his own he is sharing the information with us. I also have something planned, but it has to wait until I have time. Anyway, I want to add that John is having to build very sensitive equipment just to prove his hypothesis. If it's this hard to measure then you have to really have faith that it matters as much as you think it does. Whatever is going on, if anything, is not at all obvious while other simple tweaks are. So what we are proposing is that people take care of the obvious things first since we can measure and substantiate them. Hopefully John finds something worth waiving the flag about.  

[romaz]

9 minutes ago, vortecjr said:

Barrows has already touched on what is taking place behind the scenes with John. While he is doing this on his own he is sharing the information with us. I also have something planned, but it has to wait until I have time. Anyway, I want to add that John is having to build very sensitive equipment just to prove his hypothesis. If it's this hard to measure then you have to really have faith that it matters as much as you think it does. Whatever is going on, if anything, is not at all obvious while other simple tweaks are. So what we are proposing is that people take care of the obvious things first since we can measure and substantiate them. Hopefully John finds something worth waiving the flag about.  

 

Jesus, fair enough.  Any measurements John comes up with will be trusted as properly done, however, whether they explain what I am hearing or not is irrelevant.  As a proud owner of your products, I will remind you of threads such as these and the conclusions they have drawn based on their measurements:

 

https://audiosciencereview.com/forum/index.php?threads/hardware-review-and-measurements-of-sonore-microrendu-v1-4.1867/

 

https://audiosciencereview.com/forum/index.php?threads/measurements-of-sonore-microrendu-streamer.577/

[lmitche]

10 minutes ago, vortecjr said:

Barrows has already touched on what is taking place behind the scenes with John. While he is doing this on his own he is sharing the information with us. I also have something planned, but it has to wait until I have time. Anyway, I want to add that John is having to build very sensitive equipment just to prove his hypothesis. If it's this hard to measure then you have to really have faith that it matters as much as you think it does. Whatever is going on, if anything, is not at all obvious while other simple tweaks are. So what we are proposing is that people take care of the obvious things first since we can measure and substantiate them. Hopefully John finds something worth waiving the flag about.  

I think it is outrageous that Sonore takes a stand against it's competition like this, suggests they are the only ones that know anything and qualified to waive the flag, while the rest of the world waits in suspense.  Worse this is done in a thread about another manufacturers product.

 

You guys should be ashamed of yourselves.  I am a supporter of Sonore, but this troll like behavior has to stop.

[vortecjr]

45 minutes ago, romaz said:

 

This is what is so challenging with digital audio.  No one truly understands it all.  What I respect about people like John Swenson and Rob Watts is that they fully acknowledge this and that some phenomena are inexplicable but just because certain observations are inexplicable, does't make them invalid.  Look how routinely Sonore and Uptone Audio get bashed on ASR based on lack of measurements.  It seems some people, purely based on theories or measurements, already know how somethings sounds even before the needle hits the groove.

No one is saying that your observations are in valid. What we think is missing a basic understanding about what needs to be considered first and what matters the most. Barrows has been addressing some points of interest already. I only speak for Sonore, but we get blamed for everything and it's never your power supply, your speakers, your amp, or your ears:)  

[romaz]

2 minutes ago, vortecjr said:

No one is saying that your observations are in valid. What we think is missing a basic understanding about what needs to be considered first and what matters the most. Barrows has been addressing some points of interest already. I only speak for Sonore, but we get blamed for everything and it's never your power supply, your speakers, your amp, or your ears:)  

 

As I have reported my findings, I have kept my power supply, speakers, amps and ears a constant.  I have never blamed you.  Not sure where that is coming from.

[vortecjr]

2 minutes ago, romaz said:

 

Jesus, fair enough.  Any measurements John comes up with will be trusted as properly done, however, whether they explain what I am hearing or not is irrelevant.  As a proud owner of your products, I will remind you of threads such as these and the conclusions they have drawn based on their measurements:

 

https://audiosciencereview.com/forum/index.php?threads/hardware-review-and-measurements-of-sonore-microrendu-v1-4.1867/

 

https://audiosciencereview.com/forum/index.php?threads/measurements-of-sonore-microrendu-streamer.577/

Captain Obvious measured a SMPS into our gear and found some noise at the output of a unbalanced DAC. Something at -110 DB or more below the peak of the test signal. He then zoomed in and in big bold letters said it's adding noise. He is not going to win a Grammy Award for it, but maybe an Oscar for best actor in a drama. Why didn't he take that same SMPS and measure a DAC via the balanced output. He didn't because it doesn't promote his agenda. Why didn't he measure a lower noise floor DAC and show that his first measurement could be beaten via balanced and unbalanced. He didn't because it doesn't promote his agenda. These threads are not about things that are very hard to measure like your spaghetti solution. What he posted about can be measured.

[vortecjr]

13 minutes ago, romaz said:

 

As I have reported my findings, I have kept my power supply, speakers, amps and ears a constant.  I have never blamed you.  Not sure where that is coming from.

My apologies that was just a side note. Just something that has been happening for a while. No one seems to talk about sound quality of their gear anymore. 

[lmitche]

4 minutes ago, vortecjr said:

Captain Obvious measured a SMPS into our gear and found some noise at the output of a unbalanced DAC. Something at -110 DB or more below the peak of the test signal. He then zoomed in and in big bold letters said it's adding noise. He is not going to win a Grammy Award for it, but maybe an Oscar for best actor in a drama. Why didn't he take that same SMPS and measure a DAC via the balanced output. He didn't because it doesn't promote his agenda. Why didn't he measure a lower noise floor DAC and show that his first measurement could be beaten via balanced and unbalanced. He didn't because it doesn't promote his agenda. These threads are not about things that are very hard to measure like your spaghetti solution. What he posted about can be measured.

Jesus, you gotta stop.  Name calling a customer solution, built from components from one of your major competitors is very poor form.

 

Personally I think you owe everyone here an apology.

[vortecjr]

23 minutes ago, lmitche said:

I think it is outrageous that Sonore takes a stand against it's competition like this, suggests they are the only ones that know anything and qualified to waive the flag, while the rest of the world waits in suspense.  Worse this is done in a thread about another manufacturers product.

 

You guys should be ashamed of yourselves.  I am a supporter of Sonore, but this troll like behavior has to stop.

So I should just sit idle and not have an opinion because a few of you might get angry with me. I'm taking a stand against the scheme until the evidence shows otherwise. 

[Octagon]

Dear all,

 

I have started this thread about Mutec's REF 10 with some specs at an early stage of its launch. We have seen some valid discussion and first reports of owners. My own report will follow at a later stage.

 

 In between some lost track in this thread. This happens but has nothing to do with some post we are recognizing now. Isn' it disturbing how some CA members with commercial background are posting lately in this REF 10 thread without staying on topic?

 

May I ask to open own threads for discussions like the ones before, in case of commercial postings please make use of your own (sponsored) forum.

 

Many thanks

Thomas

[vortecjr]

15 minutes ago, lmitche said:

Jesus, you gotta stop.  Name calling a customer solution, built from components from one of your major competitors is very poor form.

 

Personally I think you owe everyone here an apology.

I'm sorry that you don't like the term Spagatti Solution, but that is what it looks like to me. 
I'm sorry that you don't like the term Captain Obvious, but maybe it's a term of endearment. I think Captain Obvious could be useful to the audio community if he didn't have an agenda.

[lmitche]

3 minutes ago, vortecjr said:

So I should just sit idle and not have an opinion because a few of you might get angry with me. I'm taking a stand against the scheme until the evidence shows otherwise. 

Yes, you should sit idle. Your hands are tied because SOTM is a competitor.  You can't win by bashing your competition. It doesn't work in any business anywhere.

 

The best response, and the one we all want for you, is for you to come back to us with a bigger, better more beautiful solution.  If you can measure and prove scientifically why it is better, that would be icing on the cake. We all have respect for all your team have done for us in this hobby,  Sonore, Barrows, John S and yourself.

[vortecjr]

4 minutes ago, lmitche said:

Yes, you should sit idle. Your hands are tied because SOTM is a competitor.  You can't win by bashing your competition. It doesn't work in any business anywhere.

 

The best response, and the one we all want for you, is for you to come back to us with a bigger, better more beautiful solution.  If you can measure and prove scientifically why it is better, that would be icing on the cake. We all have respect for all your team have done for us in this hobby,  Sonore, Barrows, John S and yourself.

Point well taken.

[vortecjr]

10 minutes ago, Octagon said:

Dear all,

 

I have started this thread about Mutec's REF 10 with some specs at an early stage of its launch. We have seen some valid discussion and first reports of owners. My own report will follow at a later stage.

 

 In between some lost track in this thread. This happens but has nothing to do with some post we are recognizing now. Isn' it disturbing how some CA members with commercial background are posting lately in this REF 10 thread without staying on topic?

 

May I ask to open own threads for discussions like the ones before, in case of commercial postings please make use of your own (sponsored) forum.

 

Many thanks

Thomas

Thomas...you have the floor. 

[rickca]

2 hours ago, rickca said:

When someone comes up with a better integrated solution ... let's call it a meatball ... maybe we won't need as much spaghetti to satisfy our appetite for enhanced sound quality.

Here's the only spaghetti we need to worry about in Florida

https://www.sebastiandaily.com/news/local/tropical-storm-maria-spaghetti-models-show-hope-for-florida-8126/

[Cormorant]

2 hours ago, lmitche said:

You can't win by bashing your competition. It doesn't work in any business anywhere.

 

Apple bashed Microsoft for years.  Worked great.

[barrows]

5 hours ago, romaz said:

Also the clock must be physically close to the active elements,with dedicated stripline PCB routing with proper termination. Running the clock externally is a crazy thing to do, as you are simply adding more jitter and noise and an extra PLL in the system

Exactly that.  Actually it appears that Mr. Watts is extolling the value of very low phase noise at very low frequencies, and internal clocking as close to the active elements as possible, and I could not agree more.

I only use the term "femto" myself because it has come to mean something to some audiophiles (hence the quotes), eventhough it does not really describe anything: is a clock with 400000 femto seconds of jitter low jitter?  Of course not.  When I talk about premium clocks for audio, I am referring to  clocks with very low phase noise at 10 Hz and below.  Although I disagree that OCXO cannot be advantageous for audio, they do address long term stability, which does not matter for audio, they are also better in some cases at achieving low phase noise at low frequencies.  I believe the Mutec is based on an ovenized oscillator, and it appears to achieve very low phase noise at low frequencies. 

[barrows]

4 hours ago, lmitche said:

The best response, and the one we all want for you, is for you to come back to us with a bigger, better more beautiful solution.  If you can measure and prove scientifically why it is better, that would be icing on the cake. We all have respect for all your team have done for us in this hobby,  Sonore, Barrows, John S and yourself.

I would suggest that, perhaps, this already exists.

 

Anyway, i have never bashed a component made by anyone.  I have suggested that some approaches, which may be used by some manufacturers are of questionable value: like using an external clock instead of using a good one internally.  Hey, look, Rob Watts, of Chord (a designer I respect very much) said the same thing...

My posting here has been towards two purposes, try to learn something myself about the Mutec products (some of which has been achieved) and try and educate some posters when they are making claims that are just plain technically wrong (like how async USB audio works).

[romaz]

5 hours ago, barrows said:

I would suggest that, perhaps, this already exists.

 

Your bias and your agenda are quite obvious.

 

5 hours ago, barrows said:

Anyway, i have never bashed a component made by anyone.  I have suggested that some approaches, which may be used by some manufacturers are of questionable value: like using an external clock instead of using a good one internally.  Hey, look, Rob Watts, of Chord (a designer I respect very much) said the same thing...

 

Barrows, really, enough is enough.

 

You should know that Rob Watts doesn't think highly of the microRendu at all but at least he is willing to admit he doesn't know everything.  Because of the galvanic isolation he has implemented in his DACs and because his pulse array DACs are inherently immune to jitter, he believes all sources sound the same with his DAVE and that the microRendu is no better than a Windows laptop.  Here is what Rob shared with me last year shortly after I bought my microRendu and I told him I was hearing an improvement:

 

"Hmm, I am somewhat bothered by the idea that the microRendu is better than a windows (it must be windows) lap-top on batteries, as there is absolutely no explanation for why that may be. But "you know nothing Jon Snow" is my favourite quote for good reason; it reminds me that there are limits to one's knowledge."

If you are going to come on to the REF10 thread and publicly question the value of an external clock like the REF10 based purely on your theories, at least have the decency to listen to it first.  No one questions the value of using a good internal clock but sometimes, the components that we buy don't have the best internal clocks and that there are external clocks like the REF10 that are better.  Your continued bleating about how using an external clock is a bad idea makes you look ignorant when those of us who have experienced the REF10 first hand clearly believe differently.  Please, enough with the insults.

[SwissBear]

In order to try and come back to the roots of this thread, which are to evaluate the interest of a Ref-10 high stability clock in the context of sound reproduction, I would like to remind a few things:

1. the debate between proponents and detractors of external clocking technologies does not seem to be a new. According to this article (http://pinknoisemag.com/pink-papers/pink-paper-002), it has longingly opposed technicians to practitioners in the pro-audio industry and is probably not closed.
2. a long cohort of satisfied customers have made the observation that the Mutec MC-3+ USB was a fantastic gear inside their system, which helped them solve most of the difficulties of USB audio reproduction. It would be an insult to these people to consider that all these customers were just fools adoring a useless component, in the same way that stating that the µ-rendu is useless would be an insult to the cohort of happy µ-rendu users. And even more so that there are many customers satisfied with the combo of µ-rendu and MC-3+ USB
3. some of these satisfied customers very lucky enough to be able to test the Ref-10 as an improvement to the performances of the MC-3+ USB and I am one of those. Having no financial interest in Mutec, I sincerely advise MC-3+ USB users to test for themselves and appreciate the improvements
4. another field has been investigated with using the Ref-10 to improve the quality of an asynchronous USB flow. Although I have not been able to witness it by myself, I trust the listening capabilities of Romaz and Mr. Lee from SOtM who have witnessed and reported significant improvement. Although less understandable from a technical perspective, this is a field where improvements have been witnessed by practitioners. So be it.

So why not, as would be fit in a free society, leave it up to each of the readers to make up his/her own mind and decide whether it is appropriate for him/her to test/buy such an equipment ?

 

Just my 2c.

[vortecjr]

Thomas I'll ask Chris to move these posts to a new thread.