Please demystify: Wordclock!

[snafu]

UPDATE (Oct 17th)
- I still don't get it (completely) -

I am so sorry, but somehow I can't wrap my head around this, so in this post there may be some redundance and moments of "duh" for you, but let me explain first:

Wordclock is needed to synchronize audio signals whenever they experienced some sort of digital conversion, when said conversion happend on different digital devices.

I hope I got this one finally right.

Now, I finally got all connections and devices that will finally end up in my set up:

- the DM3200 as central audio interface; my direct connection to the PC.
- one MOTU 2408 MK III connected via TDIF [ 8 I/O]
- two TASCAM DA 8 connected via TDIF [each 8 outputs, so 16 O in total]
- one FOCUSRITE OctoPre connected via ADAT [8 I/O]

Now: I have one BNC cable so far, two ADATs, and three Sub D-25 with Tascam Norm.

While I was looking up everything about wordclock on wikipedia, delamar, and in forums the last weeks, I found some interesting statements (of which I can't confirm one, since I have no practical experience whatsoever):
- although I could connect all devices in series, this would result in other problems, so I should consider parallel connection.
- parallel connection would therefore need a central clock (a dedicated clock device I guess), and all BNC cables from this clock to all other devices to be the same length.

Now, to be honest, this asks too much of me at the moment. So, to set up everything right, I would now need an external wordclock. Or some kind of wordclock distributor?

As always, best regards, your's truly confused
snafu

 

[Arjan P]

IMO, yes - the most optimal setup would be with a central clock source sending WC in parallel to all units. BUT, do you need most optimal (mostly used with high end converters), or is functional enough? Word clock and the series setup has been in use for a long time and if you terminate correctly and the units aren't too far apart (I would assume they're very close together) I don't think you'll have any issues. Just my two cents.

BTW, nice setup! I think you've really maxed out the possibilities on the DM3200!

 

[snafu]

Thank you, Arjan. I don't know, wheter you saw that image file, I linked to earlyer (see last page, one of the last posts): the siderack is below the window, and a bit hidden by my PC-case door. As for the Motu unit, the OctoPre, and the two Tascam DA8's, they are located in the siderack - I need aproximately 3 meters of cable from the DM to the siderack; the TDIF-devices themselfes are only a couple of centimeters away from each other (ca. 30, to be precise).
So, I'd say functional is enough, but I found an Apogee bigben for about 500 € (way back they cost a lot more...), respectively a Mutec smart clock 3+ for 699€. Not exactly what I would call low-priced, but in comparison to the top-notch-high-end-devices... .
What do you think? Is the price (especially for the apogee) worth a second thought, or is it better to put all decvices in a row?

P.S: I think (!) I finally understand. Problem is: I had all the time only the Motu-unit. With this alone, I had no need for clocking anyway. The OctoPre came a bit later, and the DA8s only yesterday - I finally get a sense for what clocking is good for. Although I must say: if I plug in any instrument or microphone I don't encounter any problems so far, but it seems, the audio experience would be hell of a difference (at least, if you believe what the "clockers" say). I thought about this again and again, and slowly I begin to understand:
though the sample rate of any device given might be 44.1k, each device has it's own "clock ticking" - so, there is no reveree saying "now", when the device should actually start to sample. So, the more players come into player, the more likely things will differ in timing. Like an orchestra without conductor. Correct me, if I'm wrong. Sorry, you see I am more the visual type of learner - I need some real life analogies

 

[Arjan P]

Yeah, I think you understand right. A master clock (whether from a series connected line or parallel) simply lines up all AD-converters to have all samples at the exact same timing.

In your shoes, I think I'd start with the series setup. There will always be Big Bens and similar devices for sale to later move to a dedicated master clock - I doubt whether you'd hear the difference though.. But - this is purely theoretical, I don't have any experience in using a dedicated master clock, maybe others who do can chime in.

 

[snafu]

Thank you, Arjan - I think you are right! It's no big deal right now, and I need to make some music asap! The last four years cumulate in these final weeks, before I can make full use of my studio and finally say: done.

 

[skier]

Hey Snafu, I fully agree with Arjan’s suggestion: save money and make this a series configuration. But seeing as your new to this part of things, I thought it might be helpful to be more specific, so here goes:

The DM is set to MASTER and is the output device with a BNC cable carrying Word Clock (also called Word Sync) out to all the other devices. The next device will have a BNC “T” adaptor with its middle connector connected to the device itself with the cable from the DM connected to one end of the “T” and another cable connected to the other end of that “T” as if the DM cable goes straight through the “T” with the middle one connecting the device (I hope I made this clear and didn’t confuse you). This device should be set to SLAVE and its termination resistor, if it has one, is OUT. Every single subsequent device will be connected and configured the same way, but with a slight difference on the last device in the chain. The last device will not need a “T”, the end of the last cable will connect directly to the Word Clock IN connector of the device. This device will still be set to SLAVE, but its termination resistor will be IN — it is the only device that should have the termination resistor set to IN.

Some people use another cable with an external termination resistor, but we’re not going to go there at this time. I only mention it in case someone told you to do that — I don’t think you’ll need it.

NOTE: If you have a device that has a fixed termination resistor that is always IN, then it must be the last device. If you have more than one, then we have a problem we’ll have to discuss, but fortunately, most devices have a termination resistor which can be switched in or out. Hopefully, I haven't overlooked anything or said anything stupid.

Good luck!