External Word Clock

[Old School]

Hi All,
Never used a 3rd party word clock before. Can I just buy a 75ohm BNC splitter cable and plug one end into the D8b and the other into my HDR with both units set to "external" in the clock settings?

Have a blessed day,
Mike

[Phil.c]

Yes, but better use two separate cables, that is if your external clock has the outlets, if I remember correctly, terminate your HDR.

[Y-my-R]

That's not how to do it right.

You need to "daisy-chain" these devices, and there should be only 2 "termination points" or I don't think you'll maintain 75 Ohms.

What you need to get is a BNC T-Connector (possibly two), and depending on the device, also separate BNC terminators (for devices that need to go at the end of a chain, but don't terminate internally).

Then you need to:

1. Connect one end of a BNC cable to the clock source - this end needs to be "terminated" with a 75 Ohm BNC terminator. That is unless the device is "always" terminated (like the Apogee Clock Card for the D8B - that one always needs to be at one end a wordclock daisy-chain, unless you are willing to mod the card to turn that off) or allows you to turn termination off or on.

2. Connect the T-piece to the second device in the chain (after the clock source), and the BNC cable from the clock source to one side of the T. This device needs to have its termination turned OFF! So, this CANNOT be a D8B with an unmodified Apogee Clock card, for example. An HDR would work in this position, though, since it lets you turn termination off.

3. Connect another BNC cable to the other side of the T (that is connected to the second device after the clock source), and the other end to the 3rd device in the chain.
Depending on if the last device on the "other end" of the chain is self-terminated (some devices are, some aren't - some mention it in the documentation, some don't. Can be a little tricky), or have a switch to engage/disengage termination (e.g. an HDR), you may also have to add another terminator at that end of the chain (via a second T-piece and separate terminator), if the device is unterminated and doesn't allow to switch that. (You may need to get another T-piece for that end, so you can connect the BNC cable AND another terminator at that end... but again, only if the device itself doesn't terminate internally or doesn't provide a switch for that)

So, basically, if you want to "distribute" clock from a single source in "star-shape" to multiple destinations (like you implied in your post... like a star with only one "center/origin" and two end-points extending from it... but you know what I mean) you need a master clock with multiple BNC clock outs.

If you don't want to use a Master Clock or don't have one, or your Master Clock only has a single BNC clock out (I think some old Aardvark clocks were like that) then the devices need to be a daisy-chained, where one device is placed after the next device and after the next, etc. (not via single source to multiple devices). And you need to be mindful about termination.

The whole point of the Apogee Word Clock card mod shown somewhere in the database, is to allow switching off the termination - so you can use the D8B at any place in such a "daisy chain" and not just at either end of it.

Also, there can of course only be one clock master in such a daisy chain (and at one end of it - at least that's what I have always been told). Everything else needs to sync to incoming word clock from BNC.

Or maybe this gives a better overview:

Device1 (75 Ohm TERMINATED! Clock Source!) ---> Device 2 with T-piece (NOT TERMINATED! Clock Slave) ---> Device 3 (75 Ohm TERMINATED! Clock Slave).

Also, before the question comes up:
Yes, there is a second BNC connector on the Apogee card and also one on DIO8 cards. These are NOT for daisy-chaining wordclock (on anything other than specific TASCAM devices that use the TDIF connectors (i.e. the DB25 connectors on DIO8 cards)).
If I recall correctly, these output a phase-shifted clock signal for use with TASCAM DA38/88 recorders, because for some bizarre reason, they needed the phase flipped (it's described somewhere in the database). If you try to daisy chain a non-TASCAM device off of these, it might work, but your clock is technically offset, and I would at least theoretically expect this to result in lots and lots of jitter (which may not be immediately apparent... but your resulting audio will not sound as good as it could - I think other than actual audible artifacts, the depth and stereo field of the signal will suffer).
Stay away from these "extra" BNC connectors on the Apogee Clock card or on DIO8 cards, unless you use them with vintage TASCAM devices and know what you're doing. (There were some revisions to the firmware on DIO8 cards, for example, where the phase used to be flipped in older versions but not in newer versions, etc. And that's a physical chip on these cards. So, it's a bit of a mess unless you're aware of all of that and factor it in when setting up).

[Y-my-R]

...and generally speaking, daisy-chaining "can" be a bit finicky and with the D8B in the setup, can result in the setup not always working right after startup (I daisy chained stuff early on when I got the D8B, but it caused trouble too often).

If you have more than 3 devices that need to be synced to the same clock source, I'd recommend to use a dedicated Master Clock with MULTIPLE BNC clock outputs.

You don't even need to use that as the clock master, and can use it to distribute the clock from another device to multiple destinations (in "star-shape").

In my setup, my UA Apollo 8 is the clock master (also b/c that's the converters I use the most often... it's usually best to have the device you use as your main input/converter, also be the clock source... unless the clock from that device is inferior... like the D8B, b/c it's so old).

From the Apollo 8, I go out the BNC WC out to a Lucid Gen192 that is set to "slave" to the Apollo 8. And from there, I go to several word clock destinations in "star-shape" that are then all clocked to the Apollo 8.
So, in my setup, I use the Lucid "Master Clock" not as the Clock Master, but as a clock distributor for the Apollo 8.

In such a setup, each end point needs to be terminated separately. Conveniently, the Lucid has LEDs in the back, that shows the termination status of each connected device, so you know if it terminates without having to find that info in the documentation (or troubleshoot if it doesn't work right).

A big benefit of a setup like that is, if there's an issue with one device in the chain, it doesn't take the rest of the setup down with it. Such an issue will only affect that ONE device.

In a daisy-chain scenario, if any of the devices cause trouble, you might have unstable clock going around. (I used to have to boot various devices repeatedly, until the whole chain finally functioned, when I still had everything set up via daisy-chain).

It really depends on the devices you want to have in the word clock "daisy chain" though. Some are pretty forgiving and easily clock to anything that comes in, while others (like the D8B) are finicky AF about that.

Master Clock/Clock Distribution for the win, IMO! At least if you have more than 2 clock destinations (in addition to the clock source).

[Old School]

Thanks for that info! I'm not quite clear about terminating the cable connected to my clock source at the source end with a termination device, can you post a link to one of these devices? What I want to do is use a Behringer ADA8200 as the clock source and send signal to the HDR and D8b. The input gains on all my d8b's are now noisy and scratchy and the phantom power is suspect as well. This unit will allow me to record straight to the HDR, bypassing this input section and simultaneously providing direct outs to my studio monitoring system and will connect to the HDR via optical cables. The unit has only one clock output.

Thanks for your assistance,
Mike

[Y-my-R]

I tried to look up if that ADA8200 is internally terminated at the BNC connector... but it didn't say in the Quick Start Guide. I couldn't find the full manual just now (but again, often that's not even listed... this lack of information was a repeated source of frustration for me in the past).

I did look at a pic of the back panel for the ADA8200, though, and it seems that the single BNC connector on that thing, can be used either as a word clock source, or as a word clock destination, depending on the switch position next to it.

This would suggest to me that IF the device should be word clock MASTER, then Behringer should have internally terminated it, since that device would then need to be at the beginning of the chain. But with this being Behringer, there's a good chance they didn't do it right (...anybody else "love" Behringer as much as I do?)

Anyway, IF the Behringer is internally terminated, and you want to use a D8B and an HDR with it, the connections would have to look like this:

1. Behringer set to "Master" via the switch next to the BNC Sync connector, at either 44.1 or 48 kHz, depending on what you use. (If the final result is for CD, 44.1 kHz is usually preferable, since the minimal theoretical quality gain of the slightly higher sample rate, usually gets lost when having to dither down from 48 kHz to 44.1 kHz when converting for CD). If it's for video/movies, 48 kHz is preferable, since that syncs better to common video frame rates).
If internally terminated, connect the BNC cable directly to the BNC connector on the ADA8200 (no separate terminator).

2. The HDR needs to be second in the chain. It has a switch in the back, that lets you engage or disengage word clock termination. Make sure it's disengaged. Then connect a BNC T-Connector piece to BNC connector on the HDR.
Then connect a BNC cable between the ADA8200 and one side of the T-Piece on the HDR.
Set the HDR to syncronize to external word clock and to the same sample rate as the ADA8200.

https://www.sweetwater.com/store/detail/BNCTAdapter--pro-co-bnc-t-adapter-2-female-1-male-2-female-1-male-adapter

3. Connect the other side of the T-Piece on the HDR, to another BNC cable, and then to the BNC connector on the Apogee clock card in your D8B. This one definitely IS internally terminated (if not modified), so don't put an extra terminator on that end. Set the D8B to synchronize to external word clock, and to the same sample rate as the ADA8200.

The only open question in this scenario, is if the ADA8200 is internally terminated, when set to act as the Clock Master (it should... but again, Behringer rarely does everything right... IMO, quite often they do NOT. That's what makes Behringer Behringer, hahaha).
If you have trouble with the synchronization, then there's a good chance that it is NOT terminated internally. And if so, you'll need another T-Piece (see link above), and a 75-Ohm BNC Terminator like this:

https://www.sweetwater.com/c809--Connectors?highlight=BNCTerm&mrkgadid=&mrkgcl=28&mrkgen=&mrkgbflag=&mrkgcat=&acctid=21700000001645388&dskeywordid=&lid=58700008506025409&dsproductgroupid=&product_id=BNCTerm&prodctry=US&prodlang=en&channel=online&storeid=&device=c&network=x&matchtype=&adpos=largenumber&locationid=9031189&creative=&targetid=&campaignid=20442635221&awsearchcpc=&gad_source=4&gclid=Cj0KCQiA2KitBhCIARIsAPPMEhLIcIU_1WerryAtYcEganBe6Rug0ttJ9eoLgkhDYUlQEN4IhJ2b5CoaArnVEALw_wcB&gclsrc=aw.ds

Again, some devices can be finicky when daisy-chained, but at least in theory, this is how you'd properly set up a Wordclock Daisy-Chain (with the open question about having to separately terminate the Behringer or not).

Btw., Monoprice sells dirt-cheap BNC cables that work just fine in my setup. Some other places charge multiple times the price of them.

Best of luck!

[Old School]

Thank you so much for that detailed info! The "T" at Sweetwater is kind of expensive, will this one work? https://www.bhphotovideo.com/c/product/ ... o_two.html


Thanks again and have a blessed day,
Mike

[Y-my-R]

Looks like the right thing. Should work

[Phil.c]

Sorry if I miss understood but I was under the impression that you were using a Master Word Clock with multiple outputs in which case one would go to your D8b and the other to your HDR with no T piece needed.

Having said that and it’s not the ideal way but about twenty years ago and before I had a master clock, I daisy chained four devices including two d8b’s from a HDR without any problems at all?

[Old School]

No worries, Phil,
Good to know that I can possibly daisy chain 4 because if this works out, I might add another.

Have a blessed day,
Mike