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RME User Forum → FireWire & USB series → Word Clock 75 ohm Termination
Hello All,
Can anybody tell me please what the effect on my Word Clock chain signal will be, when I have a digital device within the chain which has permanent 75 ohm internal termination? Will this device diminish the voltage of the WC signal, and if so, will placing a FF 800 next in the WC chain allow the WC signal to be perfectly regenerated?
Best Wishes
Jim
I would suggest to keep the device at the end of the WCK chain.
But then, you can always try how much the FF will be affected...
Regards
Daniel Fuchs
RME
Hello Daniel,
I am not able to place the 75 ohm WC terminated device at the end of the WC chain due to physical limitations in the studio.
Can you tell me please if the voltage of the WC signal will drop if I use a "T " adaptor at the WC input of a device that has permanent 75 ohm termination inside the WC chain?
Thank you for your help.
Jim
Hello to All,
Can anybody tell me please if it is OK to plug a BNC "T" adaptor into the WC output of my FF 800 with one arm of the "T" adaptor connected to a 75 ohm internally terminated WC device and the other arm plugged into another 75 ohm internally terminated WC device?
I am trying to connect two terminated devices to the WC output of the FF 800.
The advantage of my proposal is that both of the devices connected to the FF 800 will be receiving the WC signal at exactly the same moment in time, if I use the same length cables???
This would be better than a WC daisy chain wouldnt it?
Have I got this right or will my proposal degrade the WC signal in some way?
Jim
NO T WITH WORDCLOCK !
You can use :
One 75 ohm plugged from wc out of the FF800 to one device.
One Spdif out to spdif in plugged from FF800 to another device.
Sync the devices following the clock signal they receive (one slave from wc, the other from spdif).
You can also use AES, ADat to realize it.
The best way to use WC is to realize wiring like a star...
One device gives the WC to all of the other. This is the reason why I send you a link from MUTEC WC distributors !
May be you feel ok with an T adaptor, but in fact you will get jitter for almost sure !
May be you feel ok with an T adaptor, but in fact you will get jitter for almost sure!
really? I've been doing this all the time and it did never occur to me that it is no good this way...
ok, I can imagine that a star-like distribution is ideal, but daisy-chaining is what the common people do, don't they? 
HeadScratch
laex
Using a T adaptor with 75 ohm is an very bad use.
If you want to do a test : Try to use an T adaptor to provide 2 videos signal to 2 diff?rent video monitors !
The image will not be stable et you will get a lot of sync problems.
This is the reason why I say : dont use T adaptor. 75 ohm does'nt support it ! it's not like audio...
Wordclock needs similar to SCSI a termination at the end of the chain!
You have to change the cables so that the last device is terminated.
If there is a device with fixed terminator you must put it to the end of the chain. Point.
This at least produces less troubles.
So change your cables accordingly, sorry.
With regards
Zapp
We use Tees to sync tons of Video Gear (a massively large broadcast facility). I believe we use up to 8-10 units in a chain per DA Output. If we relied strictly on DA's - we'd have DA's piled up everywhere 
I'd think the active circuitry in a DA would have more detrimental effect on jitter than the small interaction between unterminated BNC inputs (of course - terminate at the end of the chain).
I'm no expert - that's for sure 
The T split is on the RME word clock in.
The Lucid 9624DA has no word clock in and locks through the optical in.
I'll get off my ass and build some cable with RG6.
You can fast with eat stop eat that's what I would like to do.
Standard/basic WC setup:
WC out -----------T---------------T-----------------T---------------------
l l l l
WC in dev.1 WC in dev.2 WC in dev.3 WC in dev.4, TERMINATED
One of my setups, with my Focusrite Octopre at the end, which does not have an internal termination option:
WC out -----------T---------------T-----------------T---- 75 Ohm TERM plug.
l l l
WC in dev.1 WC in dev.2 WC in dev.3
spdif out dev.1
l
l
spdif in - PC audio interface
(PC synced to this input)
Geir.
RME User Forum → FireWire & USB series → Word Clock 75 ohm Termination
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