Tascam DA-78HR - DTRS - Word in / SPDIF

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Thu, 03/29/2007 - 05:00
cemart
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Joined: 03/29/2007

I want to use my Tascam DAT DA-78HR in slave mode with an extern word clock, the word-in-signal through a BNC connection.
In this case unfortunately I can´t use the S/PDIF out of the DA-78HR to connect it to a sound card, because this signal gets the worst cracks.
S/PDIF out seems only to work when the DA-78HR is the master unit.
But why? Could anybody help me?

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Thu, 03/29/2007 - 10:13
#1
tonybrooke
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Joined: 02/12/2009

Is the external word clock you're using to clock the DA-78HR coming from the sound card? If not, you'll get clocking errors because the sound card is not running off of the same clock as the DA-78HR.

If the external clock is coming from a third device, try sending it to both the DA-78HR and the sound card. If the clock generator only has one output, try a BNC "T" connector.

If you don't have the necessary word in/out jacks, you can also try clocking off of the DA-78HR's coaxial (S/PDIF) jack.

Also, be sure all devices are set to the same sample rate.

n/a
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Thu, 03/29/2007 - 10:34
#2
cemart
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Joined: 03/29/2007

Thanks for your answer.
I want to use my external clock, an Antelope Isochrone OCX and I connect this to the DA-78HR with a BNC connector.
I tried also to get the clock from the Isochrone to my RME sound card and I too connected both star like from the external clock.
The last one worked very well when I send the signal from the sound card through S/PDIF to the DA-78HR, but the other way it was impossible.
As soon I send S/PDIF signal out, DA-78HR doen´t work anylonger in WORD IN position.

Greetings from Northern Sweden

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Thu, 03/29/2007 - 12:06
#3
tonybrooke
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Joined: 02/12/2009

Ah, yes. It sounds like you have everything wired correctly. It should work in both directions. I'm stumped. If it's possible to call the US, try Tascam tech support, 323-726-0303. They are in Los Angeles CA, USA.

Or the European offices are listed here:
http://www.tascam.eu/en/1024.html

n/a
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Sat, 04/21/2007 - 05:53
#4
cemart
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Joined: 03/29/2007

could a 50 ohm termination help - as you wrote in the DA-78 Special Report?
(and by the way, thanks for this helpful report with all tips and tricks, very good work)

Quote:Wordclock termination
Yet another hardware design flaw is easily fixed. The word clock input jack is not terminated correctly.

Get a BNC "T" connector (Radio Shack part #278-270) and a BNC 50 ohm terminator (RS part # 278-112). Make sure that the terminator is not 75 ohm. Connect the terminator to one side of the T, and plug the T into the Word Clock input. Plug your clock source into the open side of the T. The THRU is self terminating as long as nothing is plugged in to it.

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Mon, 04/23/2007 - 10:32
#5
tonybrooke
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Joined: 02/12/2009

It's worth a shot, as the 50 ohm terminator and t-jack are both inexpensive. (Remember to mark your 50 ohm terminator so it doesn't get mixed up with any 75 ohm terminators.)

However in my experience, word clock termination problems are subtle. Your crackling issue might be a larger problem.

Please do report back on your results, this is a good mystery.

n/a
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Sat, 07/14/2007 - 13:43
#6
cemart
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Joined: 03/29/2007

I tried with all kinds of termination, it didn't help. So I found no way using extern word clock during S/PDIF signal out.
Now I have a new setup, using a Tascam IF-AE8 between the 78HR and my RME sound card and it seems to work. First from 78HR to IF-AE8 through a Tascam D25 cable and then AES.
And I really recognized that using an external word clock improves the sound quality a lot. So all 3 units are star like connected to word clock through BNC.

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