Can someone explain the clock sync?

@brbrock Well I can only go by what I was told by the dealer I bought my T15th from and at this time there are no plans for a Flagship DAC, maybe in a few years. So the Terminator15th IS the flagship. It certainly sounds like it to my ears. I understand that Denafrips still has some of the T+ Faceplates they want to sell off.  I think that is why they are tight lipped about the T 15th detailed specifications, they lead you to thinking it is a replacement for the old Terminator II, but that is basically the new Venus 15th. At some point they will be forced to spill the beans to make all the models make sense.

@fthompson251 Since they rebadged the Terminator plus to the Terminator 15th are they going to create a new Terminator plus?  The Terminator plus is still for sale on the website.

@fthompson251 wow 👌 if that is the case then your 15th and the Venus 15h at $3700 are smoking deals. Tempted but thinking of the new Weiss DAC502 Mk II because of the DSP functions.

@kairosman  I missed your question about the Terminator 15th being a rebadged Terminator Plus. It seems to be the case from all that I can gather-it is the same other than the faceplate. It is also my understanding that the 15th engineer team did some programming enhancements through the FPGA, but I am not positive. It is surely about the Terminator II level which is now supposedly the new Venus 15th. 

The sync clock for digital isn't the same as the syncing to movie's 29 frames per second or TV's frame rates together such that the sound and visuals are synced. That is called SMPTE timecode.

PS - Never meant to imply it was the same thing.  Just that when mastering a multichannel movie you may have even more devices to keep in sync than stereo mixdowns.

The sync clock for digital isn't the same as the syncing to movie's 29 frames per second or TV's frame rates together such that the sound and visuals are synced. That is called SMPTE timecode. When digital audio came to being in the mid 70's and one of the big issues with any digital signals is a when you try to mix two or more sources together - the summing together of digital signals is how to sync them together such that you don't get drop outs or aliasing issues. So a word clock was developed so that every pro digital equipment could follow one word clock. The easiest way to bypass that is to place it back to analog and re-sample the analog signal back to the digital domain. But if you want to keep it in the digital domain then work clock is the most preferred way. There are quite a few standards of digital audio - S/PDIF, AES/EBU, MADI ( subset of midi) ADAT and TDIF. They all use word clocks to sync thing together, but there must be only one word clock. Then there are units that will sync together digital signals from machines that don't have the capabilities to sync (or adjust their internal clocks) such that the signal will get reprocessed to sync into the main stream digital audio. 

Home audio isn't as complicated, and for the most part isn't really needed. Your cd collection once placed into your PC will follow your PC word clock, or if any of your equipment has a word clock, it will convert it's clock over. Cd players that have word clocks are mostly masters. It gets quite expensive to have adjustable clocks on such devices - you need a fairly large buffer to hold the data before syncing. In the studio these days most of the work flow are on PCs, so you just download the data into the PC and away you go. 

If you have a good CD collection, it's just better to download the data into a dedicated PC and play from there. Far better that any CD player on the market that I know of. 

Thank you @kairosman ​@audphile1 ​​​​@erik_squires for your responses. 

Hey OP,

The idea behind a master clock comes from the pro world where you might have many digital sources that had to be kept in synchronization. Especially true for movie production. You can’t have skew.

The only time skew is really an issue for home AFAIK is in a situation where you have an external CD player and separate DAC. A master clock will ensure the CD player gives the DAC bits just in time.

The thing audiophiles and vendors try to do by spending more money is reducing jitter figures. That is, ensuring that the width of each step in the signal remains exactly the same. Not something external clocks were meant to do, but they have some possible uses.

The lowest phase error is now going to be by putting a very good (femto-) clock right next to the DAC. The longer the distance between the clock and the DAC the more error you can have, so having a clock and cable plus internal distance travel means the internal clock MAY outperform any external clock. Benchmark has a good white paper on this and Mytek also wrote about this.

Probably the best idea for home would be to use the DAC’s clock as the master, have a buffer, and sync external sources to it. Asynch USB DACs do this, but some also have clock out capability, allowing the DAC clock to control an external CD spinner. Combination DAC/Streamers do a similar thing but usually have up to several seconds of buffering. Roon does something like this in their server.

Before Async USB DAC’s attempted to fix these issues by guessing the incoming clock rate and buffering the input. They still do this when needed such as for S/PDIF inputs.

Also, lastly, in the last 10 years or so chip clocks have gotten SO much better than they were before. Unless your DAC is old the internal clock is probably going to be the best reference.

My understanding is clock synching between two devices has the clocks work together seamlessly when clocking signal inputs, so the signals the Hermes are fed are clocked in tandem with the clock in the Terminator. IOW the two devices "are on the same page". This synching supposedly lowers jitter thus distortion, sonically speaking this supposedly improves phase coherence thus clarity. In my system this benefit has been mercifully clear, but often others report little to zero audible improvement. Congrats on the Terminator 15th, curious to know if the rumor is true that it's a rebadged Plus.

@fthompson251 

This information from the Denafrips site should help

In short, your DDC reclocks the signal from your streamer before sending it down to the DAC. There’s also DSP that takes place. The objective is to lower jitter to levels where it is no longet a factor for the DAC. The i2s into the DAC is then extremely clean. This supposed to result in better sound. 

I would not worry about any of the clock stuff. The whole jitter-worry is overhyped as with anything remotely contemporary, jitter is not audible at the values found in contemporary digital devices. See here for a discussion:

https://audioxpress.com/article/audio-electronics-is-digital-jitter-really-a-problem

You don't worry about MHz output in the audio signal, as it is equally irrelevant. If you hear differences in DACs, it may be a whole lot of things before I would consider jitter.
Also the video linked above explains nothing about what is supposed to happen with this clock stuff, just how to do settings on a particular device.

Just enjoy the music!

It should sync the Hermes internal clock with the Terminator clock as the master.  It is intended to reduce jitter.

@jastralfu I know how to do it, I have it set up. What I wanted to know is what it does. How does it work? Thanks.

@jond I just want to know what exactly it does.

I am talking about the 2 BNC Cables connected to the clock output of the DAC to the clock inputs on the Hermes, what does this accomplish?

Regardless of how it works you will never know it's an improvement until you stop using the clock and compare. It may be a PITA but it's the only way to really know.

This should help 

https://youtu.be/db3YaZnZcuE?t=187&si=v-IymvSihryqKfIb

If it’s set up correctly it should sync to the clock in the DAC.  I’ve never set it up  since I have my Hermes connected to a Pontus II so I can’t help you there but there should be videos on the Denafrips site that can help you confirm your setup.