Mutec Ref-10

[baconbrain]

I had a look at the Ref 10 during the 2017 High-End in Munich and have been contemplating procuring one since.

@Swissbear: Glad to hear that your experiences with the device have been so positive and thanks for sharing your impressions.

Ultimately for me, I believe that the investment is only warranted when I can connect multiple devices (at least three) to the Ref 10. Given that I will be receiving a SoTM 200 Ultra with Word Clock input sometime within the next few days, I would then have 2 which the Ref 10 could feed. Which leads me to my next questions...

My Trinnov does not have a dedicated word clock connection but can either be set as master (using it's own internal clock) or slave (using the clock signal enclosed within the audio signal via BNC, in may case, received via the Mutec MC-3+) Can anyone explain how exactly does clock cascading work? How does the Devialet operate in this regard? What advantages does a dedicated Word Clock input provide over a cascaded one?

Questions, questions ...

[Confused]

Many questions baconbrain!  

It looks to me like you do already understand the basics of this topic as well as anyone, but are perhaps looking for explanations that simply do not exist, certainly in the area of 'clock cascading', an area where I have been looking for answers myself.  

Anyway, some thoughts from myself.  The sMS200Ultra does not have a 'word clock' input, it has a 10MHz reference clock input (or 'master clock' as SOtM call it).  A slightly pedantic comment I know, but these are different things.  Of course the Mutec REF10 is a 10MHz reference / Master clock. So a 10MHz reference clock input on the sMS-200Ultra is what you need.  

AES3 protocol includes a clock signal embedded in the feed.  So, if the REF10 is providing the clock to the Mutec MC3+USB, then the REF10 clock signal should feed to the Trinnov and then on to the Devialet.  It is not clear exactly how Devialet use the clock signal in the AES3 feed (AES/EBU), but if it was not using the clock in the feed then SwissBear would not be hearing the improvement that he is.  Indeed, if we assume that the implementation of the AES/EBU input is the same in principle as it was on the 'old' Expert range, we have to assume that the Devialet uses this embedded clock, otherwise SQ would not improve with Aurender W20's N10's, Mutec MC3's, dCS Vivaldi's and so on.  There have bee too many reports of Devialet SQ improvements via decent AES/EBU sources to make any other assumption.

So, you can attach the REF10 to you sMS-200Ultra, and your Mutec MC3, and in theory the high quality clock signal generated by the  REF10 should make it all the way to your Devialet.  Which is the point I think, you state that you need at least three devices to run from the REF10 to justify it's cost, I am not sure I would agree with this.  What you need is for the best possible clock signal to make it to the Devialet, and for this to offer a sound quality improvement that justifies the REF10's price.  The bit I cannot explain is why connecting the REF10 to the sMS-200Ultra will help, because the Mutec MC3+USB has an asynchronous  USB input, so the clock in the Mutec MC3 (improved by REF10) will govern here.  In theory at least, the 'clock cascaders' on CA say different, even claiming that the clocking the Ethernet switch makes a big difference.  (the modified switch is a relatively cheap option with the sMS-200Ultra, so you might want to try this, even though there is no current explanation why it should work!)

So to your question, 'Can anyone explain how exactly does clock cascading work?'  If you are referring to the use of a master clock running multiple 'up stream' devices, I do not think anyone has a satisfactory technical answer as to why this works, but many state that it does work.  The first half of post #7 of this thread covers this one, as does about 100 pages in a thread on Computer Audiophile.

[baconbrain]

Many questions baconbrain!  

It looks to me like you do already understand the basics of this topic as well as anyone, but are perhaps looking for explanations that simply do not exist, certainly in the area of 'clock cascading', an area where I have been looking for answers myself.  

Anyway, some thoughts from myself.  The sMS200Ultra does not have a 'word clock' input, it has a 10MHz reference clock input (or 'master clock' as SOtM call it).  A slightly pedantic comment I know, but these are different things.  Of course the Mutec REF10 is a 10MHz reference / Master clock. So a 10MHz reference clock input on the sMS-200Ultra is what you need.  

AES3 protocol includes a clock signal embedded in the feed.  So, if the REF10 is providing the clock to the Mutec MC3+USB, then the REF10 clock signal should feed to the Trinnov and then on to the Devialet.  It is not clear exactly how Devialet use the clock signal in the AES3 feed (AES/EBU), but if it was not using the clock in the feed then SwissBear would not be hearing the improvement that he is.  Indeed, if we assume that the implementation of the AES/EBU input is the same in principle as it was on the 'old' Expert range, we have to assume that the Devialet uses this embedded clock, otherwise SQ would not improve with Aurender W20's N10's, Mutec MC3's, dCS Vivaldi's and so on.  There have bee too many reports of Devialet SQ improvements via decent AES/EBU sources to make any other assumption.

So, you can attach the REF10 to you sMS-200Ultra, and your Mutec MC3, and in theory the high quality clock signal generated by the  REF10 should make it all the way to your Devialet.  Which is the point I think, you state that you need at least three devices to run from the REF10 to justify it's cost, I am not sure I would agree with this.  What you need is for the best possible clock signal to make it to the Devialet, and for this to offer a sound quality improvement that justifies the REF10's price.  The bit I cannot explain is why connecting the REF10 to the sMS-200Ultra will help, because the Mutec MC3+USB has an asynchronous  USB input, so the clock in the Mutec MC3 (improved by REF10) will govern here.  In theory at least, the 'clock cascaders' on CA say different, even claiming that the clocking the Ethernet switch makes a big difference.  (the modified switch is a relatively cheap option with the sMS-200Ultra, so you might want to try this, even though there is no current explanation why it should work!)

So to your question, 'Can anyone explain how exactly does clock cascading work?'  If you are referring to the use of a master clock running multiple 'up stream' devices, I do not think anyone has a satisfactory technical answer as to why this works, but many state that it does work.  The first half of post #7 of this thread covers this one, as does about 100 pages in a thread on Computer Audiophile.

Confused,

Thx for the well phrased response. My thought pattern behind having at least three devices to justify the cost for the Ref10 was based on the uneducated presumption that cascading only goes to the next device in the chain. Given that I have four (Sotm > Mutec > Trinnov > Dev), I assumed I needed three.

If you gentlemen have the patience, I also have another question for you ...

All of the Ref 10 connectors are BNC with 8 (I believe) of them 70 ohm coax and two 50 ohm coax. With the Dev using a 100 ohm AES connection would it not be better for the sake of of cascading to feed it with a 70 ohm coax instead?

[Confused]

If you gentlemen have the patience, I also have another question for you ...  

All of the Ref 10 connectors are BNC with 8 (I believe) of them 70 ohm coax and two 50 ohm coax. With the Dev using a 100 ohm AES connection would it not be better for the sake of of cascading to feed it with a 70 ohm coax instead?

Depends which cable you are referring to!  For the clock reference cables from the REF10 to the Mutec MC3 or sMS-200, you need to make sure you have exactly the right cable.  For example, I believe the Mutec MC3 has a 75 ohm BNC, so you need a 75 Ohm cable with 75 Ohm BNC connectors.  I have been reading about some 75 Ohm clock cables that have 50 Ohm connectors, because they look the same but are cheaper.  Double check this, you need 75 Ohm cable with 75 Ohm BNC connectors.  I think the sMS-200Ultra comes with a choice of 50 or 75 Ohm input, so use the matching cable.

The BNC (S/PDIF) connectors on the Mutec MC3 are also 75 Ohm, the XLR (AES/EBU) style connectors are 110 Ohm, which will be exactly the same on your Trinnov.

[baconbrain]

I guess it is just not my day today. Can't even get my numbers straight ....

Understood. The intent of my question was to ask if it would be a better idea to connect the Dev to the Trinnov with a 75 ohm coax cable instead of a 110 ohm AES in the interest of clock cascading?

[Confused]

I guess it is just not my day today. Can't even get my numbers straight ....

Understood. The intent of my question was to ask if it would be a better idea to connect the Dev to the Trinnov with a 75 ohm coax cable instead of a 110 ohm AES in the interest of clock cascading?

In terms of the AES3 protocol and how the clock signal is transferred and used, it should make no difference.  However, the AES/EBU input to the Devialet is preferred, so use that with a 110 ohm cable.