Word clock cables....bitching things

[Cape]

Sorry this is second post in about as many minutes,

Wordclock cables, can you buy a extension (no penis jokes please!!), why do they always come so small!! Do I have to use my defunct (use here and there) DBX quantum as the extension!!

I can run digital devices clocking to aes, but to some that really doesn't work , digi's 192 sends out some heavy clocking info, that freaks out Focusrite's, Eventide's internal readers, it seems!!

So why can an XLR carry wordclock miles and them silly little WC cables only a foot, stupid, stupid, stupid.

[Steve Smith]

I have a 30'WC cable, no problems.. just buy em longer...

[Cape]

Cheers dude, just got the idea from other peeps that they needed to be a ft long for accuracy. But I'm not doing Steven Speiliiiiberg movies, so I'll hunt em down.

So many things to know, it's like a friging quest for the truth.

The Q remains the same.........what has a Wrd clock cable got that a AES cable aint??

[droog]

You can get a feedback loop if you use AES for you clock source. E.G. your eventide is connected to the AES inputs and outputs of your 192 I/O in a fx send / return configuration. The clock information is going out and coming back in. sometimes it works , sometimes it doesn't.

Word clock is meant to be used serially , not in a loop , hence no feedback

[BrianT]

The reason for the difference in recommended length is primarily because AES is a balanced, 3 conductor circuit as opposed to Word Clock, which is an unbalanced 2 conductor circuit.

There is therefore some truth to the notion that WC cables should stay relatively short. The quality of the cable itself, correct impedence matching, proper termination, RFI and EMI in a particular location, as well as the specific driving and receiving circuit designs all come into play.

So the high number of variables gives rise to one person saying "Any length is OK" as opposed to another person who says, "Keep WC cables very short", with both possibly being correct in their particular install.

The answer is, use the best WC cables you can afford and keep the length as short as is practical. Personally, WC cables past 3 feet make me a tad nervous and over 10 feet is a definite "No" for me.


Regards,
Brian T

[Steve Smith]

Brian, It does totally depend on the cable, the gear, the time of day... I generally go with the short as possible, and as may as poss the same length, but if you use a good quality cable ( appogee, monster, etc) it can work fine..

[chap]

ideally, all your word clock cables should be the same length (I admit to having one long one of out 8)
and correctly terminated at each device. Apogees like a 'T' connector with a 75ohm terminator on the other side. This rig will be more stable than any conventional AES clocking.
Even when running a house synch, it's still better to clock your word clock to video and then distribute wc to the remaining devices.

[NYC Drew]

Originally posted by chap
ideally, all your word clock cables should be the same length ...

Why? What's the logic?

more later on co-axial (75 ohm wordclock cables) versus 110 ohm cables...

[Steve Smith]

The asame length theroy works on the principle that same length = same time of delivery.. I feel that the spped is so great and the distances so small that in a typical studio it is not a super important issue.. YMMV, in my rig it doesnt.

[chap]

hence the preface 'ideally'.
110 ohm cables are best for digital audio and 75 ohm for carrying clock stuff.
If I knew all the logic, I'd make the shit, I just use it.

[Cape]

Okay, I'm getting lost amongst all this 110ohm, 75ohm stuff going down.

Thanks for the info and I'll use it no doubt when I'm next drunk and blagging about what I know (nothing about).

But my eventide can't lock to the 192, even on the smallest wc cable at 96khz, you've gotta keep telling it to go to ext wc, and after your 100th try it get's it (and then, when you re-open session!!!). All the other 99 times it will go either down to 46,750khz or something stupid??, this is surely as case of the Digi super clock, the clock that ticks very fast indeed.

I've got a ISA220 that clocks to the 192, through it's output AES??? I'm not planning on keeping it this way, but it's funny it can do it, weirdo.

Well, it's 3ft WC cables for me now, I feel safe and happy that I don't have to have every bit of digital gear stacked on top of one another.

[Magic Genie]

I just got the Lucid AD9624 Convertor from another relaly nice fellow Gearslutz member, and have the Waves L2 convertor. Both of these have Word Clock in and no OUT.

My Word Clock master source is the 828MK2.

Do you know how if I can use a Y-cable or some inexpensive box to "split" or Duplicate or otherwise distribute wordclock to both of the A/D convertors?

Thanks in advance!

[marc@soundpost]

Lucid makes a word clock distribution amp. They dont cost much either. I use 2 of them in studio 1, and another in studio 2. Both rooms have the Apogee word clock cables and the SSG 192 word clock generator). The system works great.
Marc McManeus

[Steve Smith]

or spend 3 dollars on a BNC "T" connector. Many folks perfer using "T" connectors rather than looping in and out of gear as well.

[Bob Olhsson]

The whole point of using word clock cables is a parallel clock connection that is separate and hence can't be modulated by the audio signal. Unfortunately, nobody has ever implemented it properly with phase trimmers such as are used with video sync so there's a bit of mysticism involved getting everything to misbehave properly. Precision 75 Ohm video cables of the same length are a real good idea however, unlike video sync, there's too much design slop to run long cables in addition to the fact that, unlike AES sync, nothing identifies the beginning of a word.

This used to be a bigger deal because of some serious design problems with the most common digital audio input chip. If you are using pre-96k. capable gear, word clock can be a good idea for locking multiple A to D converters together or for cleaning up your monitoring if you don't have a jitter-resistant D to A. With gear that uses the latest chips, AES sync (AES/EBU black, i.e. no audio signal) or even self-clocking with an AES/EBU signal is going to be fine unless the manufacturer really screws up. (something that is not unprecedented...)