Digital Audio - Wordclock Expansion Tip!

[frederic]

For those into digital mixers, synths, recorders etc, you've probably discovered there really isn't an obvious way to hook everything together easily, without spending a bundle on something like an Lucid Wordclock Generator followed by a 1-in, 6-out Lucid splitter.

Of course, what do you do if you have more than six devices that require wordclock in? Like me, I have 7 tascam mixers, 6 akai recorders, and four synths that want wordclock. That's 17 - ack!

Well, here is a neat trick I just tested out. Wordclock is 75 ohm, cable TV is 75 ohm.

Hmmmm.

So, I buy myself a Radio Shack "Gold Series" 150-1235 Coax Splitter/Combiner, 1 in and 4 out, and attach the input to one of the six outputs of the Lucid that I have. I took a piece of Coax TV cable and cut off one of the F connectors, and crimped on a BNC. You can also buy adapters if you like spending money. Then, I ran four RCA-RCA cables from the splitter to four tascam mixers which have RCA wordclock in and out. Fired them up - wow, they all saw wordclock.

Neato!

Then I added another coax TV splitter to the second wordclock out on the Lucid, and attached the splitter (same method) to the two remaining small tascam mixers, the TMD-4000, and one of my akai recorders. They too saw wordclock.

Neato!

I then attached the remaining splitters I have to the other Lucid outputs, giving me a total of 24 wordclock outs out of the Lucid.

If you don't have a six output Lucid wordclock, you could just as easily use an aardvark wordclock generator, or one of your digital mixers, recorders, whatever, as long as the wordclock output is stable. Use cable TV splitters and have at it - its fairly cheap and one less wall-wart to stick in your power strip.

Off to rat-shack for some more coax Catch ya in a bit...

[xstatic]

In theory it sounds like it would work. In practice, I am not so sure I would do that. However, it might be better than not clocking at all.

[frederic]

Originally Posted by xstatic

In theory it sounds like it would work. In practice, I am not so sure I would do that. However, it might be better than not clocking at all.

Well, forget theory, I have everything wired for wordclock minus the Triton and everything seems happy. The local rat-shack didn't have enough of the splitters I bought, so I ended up with four of first style, and one labeled "Satelite Dish Splitter", which doesn't work at all. Obviously, has high/mid pass filter, leaving lower frequencies out. The cheapo ones I bought initially, don't seem to have that "feature".

I'll let you know in a month if anything catches on fire

[knightfly]

Frederic, do you have a fairly high frequency (maybe 100 mHz) scope you can look at the outputs of your Rat Shack splitters with? I'd be curious what the pulse shape looks like going through those, and how much delay they impose. 'course, if you're running ALL your WC's thru those and delay is the ONLY problem, then it's a NON-problem... :=))

[frederic]

Originally Posted by knightfly

Frederic, do you have a fairly high frequency (maybe 100 mHz) scope you can look at the outputs of your Rat Shack splitters with? I'd be curious what the pulse shape looks like going through those, and how much delay they impose. 'course, if you're running ALL your WC's thru those and delay is the ONLY problem, then it's a NON-problem... :=))

Definately have a scope (four actually), I'll grab one from my workbench tomorrow and take a look-see as to how it compares to the original signal in quality, delay, and voltage level.

I imagine the degregation is extremely small, or out of coincidence, my gear is very tolerant. Either way

And yes, gear will be connected to the splitters, and never the Lucid wordclock - for that very reason. Though before I moved to NJ (4 years ago), I had one TMD1000 set as the master wordclock, and the other five got their wordclocks through the daisy chain of s/pdif outs and ins down the line, and was never a problem. I did have syncing problems with the TMD4000 which was last in the chain, but I solved that by taking wordclock out of the first mixer, and feeding the TMD4000 wordclock directly. No clicks no pops, but I know that was just shear luck. The only thing that did "suck" was if a mixer earlier in the chain did something funky, all the mixers down the line would reset, and blink "wordclock invalid, using internal clock" and then I'd get pops, clicks and buzzing. Nice for the monitors

Irrelevent to this thread... but something I found amusing, is that the six TMD-1000 mixers have different concepts of 48Khz. Ranging from 47.917Khz to 48.210Khz. The TMD4000, the big "professional" mixer covered that entire range based on temperature directly. As the internal power supply headed up the interior of the console, the wordclock would slowly drift (over several hours) as high as 48.5Khz, which is why I didn't use it as the master. My akai recorders even though they are older than the mixers I have, were by far the most stable as far as wordclock. However, if one were to switch between the analog ins (burr brown converters) and the lightpipe card, wordclock would briefly be stopped while the digital interface resets. So, anything conneted to that would just to nuts. And since I ran my mixers as a daisy chain, that would make everything go nuts and require 15 minutes of going through ergonomically obnoxious menus resetting everything.

This is why I bought the Lucid in the first place - it powers up when the computer is turned on, so its always ready for the gear, which gets turned on second.

I'll post results tomorrow of the scope viewing.

[Track Rat]

Hmmm. The 4 ways have about 7.5 to 8 dB of loss per leg but if you have at least 1 V p-p, it should work. Have you thought about using BNC Ts and daisey chaining maybe 4 devices per output of the GenX?

[mshilarious]

There's a really long, long thread on Dan Lavry's board where he talked about this. I don't understand it at all, but here's the link:

http://recforums.prosoundweb.com/ind...51/0#msg_23451

[frederic]

Originally Posted by Track Rat

Hmmm. The 4 ways have about 7.5 to 8 dB of loss per leg but if you have at least 1 V p-p, it should work. Have you thought about using BNC Ts and daisey chaining maybe 4 devices per output of the GenX?

Yes, I have. This works for the TMD4000 and the Akai recorders, as they have switches to disable the built-in terminators. The other equipment, alas, does not, so daisy chaining (which I tried) results in the signal going only so far... then dying. I tried

That's one difference between "pro" gear and "consumer" gear - "Pro" stuff allows you disable internal termination.

[frederic]

Great link MsHilarious, and probably explains why what I've done works well (so far).

Scoped it out using a 2 channel scope comparing the original signal to the output, and the output signal is a little more rounded than what goes in, but not by much. 1.5V going in square wave from the lucid, and about a volt coming out with a little bit of noise on it. Not sure if that's my scope, or the splitter. I'll get the real scope up here tomororow.