Various ways of syncing converters...

[thebigcheese]

I've been trying to find some information on the advantages/disadvantages of the different ways of synchronizing converters, but I can't seem to find a whole lot of information. There's word clock sync over BNC, there's ADAT over an optical cable, there's AES/EBU (I think, though most things I've seen don't have that), and there's firewire when you chain several interfaces.

I have heard that ADAT isn't a very good way to sync, but I have no idea why. It seems to me that word clock would be affected by the quality of the cable since it's an analog signal (right?), which would be less ideal. But ADAT is digital, so the cable would be irrelevant. I would think the same thing would apply with firewire, but I've never seen a standalone converter with that. And I don't know anything about AES/EBU and don't have anything that can do it anyway, so that one doesn't matter to me. Can someone point me in the right direction?

 

[samth3mancgp]

I slaved my Project mix I/O to the clock on a Presonus Digimax preamp via ADAT with no problems whatsoever for about a year. I now use a Black Lion Audio microclock MK2 that syncs via BNC cable. I don't think that the interface (cabling) used to clock your converters really matters, though there are some that say that using a dedicated master clock for multiple digital devices can result in a nicer overall sound when stacking lots of tracks.

I am no professional, so I do not claim to know everything there is to know about this stuff..

I have been reading about clocking quite a bit over the last few days. What seems to be the general conclusion is that the internal clock of your interface will always have the cleanest signal, and that slaving it to an external clock of any kind will actually introduce MORE jitter, even if the clock is labeled as having low jitter by the manufacturer. A college professor here at school told me that:

"Your BLA clock may start out clean at the source, but by the time it is transmitted through a cable, has (probably) 100's X the jitter that your Presonus has internally. It may not be a better clocking system after all, just different. It's really the receiving equipment's ability to resolve the clock and reject the transmitted jitter that is important here."

Here is an artice from SOS that shows how even some of the most high end clocks on the market actually REDUCE converter performance compared to internal clocks. This increased jitter can result in a change in sound that some may find desirable in sound, but are actually lowering the performance of your converters.

I paid $500 for my BLA microclock a few months ago, and after doing all of this reading I am kind of shocked.. I feel that that Microclock has improved the sound of my system, but this is actually due to introducing MORE jitter, not less!

 

[thebigcheese]

I read that article, too, which is why I will just be using my Firestudio as the master. On the other hand, I could use my Digimax D8 as the master if I use ADAT to sync. I thought I had read that ADAT sync isn't as good because you're also sending audio and somehow it's bad to have both, but it seems to me that a digital signal would be more reliable... And then I was wondering if it's actually any better to use a Firestudio and a Digimax or to just chain two Firestudio Projects.

 

[samth3mancgp]

I wouldn't lose much sleep over which of those two is going to work better. Do you already have two firestudio interfaces? Or just the Firestudio and the Digimax ADAT pre? Maybe go with whatever is cheaper? I never had any problems syncing clock signals over ADAT when I did I was set up that way.

I slaved the project mix to the Digimax because I felt that the presonus stuff had better hardware in it (everything from the preamp design all the way down to the clocking signal) than the Pmix. Even at that point I only felt that there was a noticeable change in overall sound of a mix when moving onto the Microclock.

In your situation where both the interface and the digital pre are both made by Presonus I think that you will not gain or lose any quality of sound by doing it either way. All this clocking stuff just makes me dizzy.

 

[thebigcheese]

I already have all the stuff to do it either way, minus a BNC terminator. I'm mostly interested in what the science or theory behind each way is. I just have one Firestudio and a Digimax, so I couldn't do it over firewire. I've also got a MOTU 2408 I'd like to use, though now that I think about it, word clock is likely to be the only way to sync all that. The D8 doesn't have word clock out or ADAT in.

 

[samth3mancgp]

I don't know a whole lot about the science behind it either. A quick google search led me to this thread on another forum.. But you've probably already seen it. The suggestion of a dedicated master clock (using BNC) is brought up shortly after the beginning of the thread. It seemed to be general consensus that the BNC is a more stable way of syncing devices. Perhaps BNC is the way to go.

If you want to be sure you are getting top quality BNC cables I would get them from Black Lion Audio. I bought them with my Microclock, one for the Pmix, one for the Digimax D8. Really really nice cables in comparison to many others that I have seen in the same price range. Oh, and the standard BNC cable is the one that I got, not the premium. Even then they are top notch stuff.

http://www.blacklionaudio.com/content.php?p=4