# Thunderbolt to BNC Splitter



## PDSaccman (Sep 21, 2014)

Is there a device out there that would allow be to take a digital signal (like thunderbolt) and distritube it across 8 different bnc monitors? Basically, I have a couple of CRTs in a show Im doing that need to all have a different videos on them that all comes from the same computer. I plan to use QLab 3 as my control software.


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## Footer (Sep 21, 2014)

Nothing off hand. What kind of signal do the monitors take? Composite, SDI.... 

Your first going to need to get 8 descrete outputs out of your computer. That is going to be a real challenge. After that, you will need to get a converter to whatever format you need. Can be done... but more information would be helpful.


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## PDSaccman (Sep 21, 2014)

Footer said:


> Nothing off hand. What kind of signal do the monitors take? Composite, SDI....
> 
> Your first going to need to get 8 descrete outputs out of your computer. That is going to be a real challenge. After that, you will need to get a converter to whatever format you need. Can be done... but more information would be helpful.



I'm doing SDI. How do I get 8 outputs? Is this something that is uncommon to do? 

Thanks for your help


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## Chris15 (Sep 21, 2014)

SDI and CRT together sounds an odd combination...


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## Edrick (Sep 22, 2014)

I think more detail is needed. Are you looking for 8 separate items playing or will you be using the same video on multiple monitors? The Mac pro can handle 4 thunder bolt displays on the newest model. Why are you using SDI?


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## StradivariusBone (Sep 22, 2014)

A device I've used with some success is the TripleHead2Go by Matrox. It essentially creates one wide display and then splits it into three components. There is an analog version that has the ability to output to VGA (which you'd still need an adapter to get to your BNC, but if you're not hung up on having a video monitor, you could conceivably find older VGA CRT's that have a similar look. To get 8, you'd need two TripleHead2Go's and one DualHead2Go (which does the same thing but with 2). I haven't used this in QLab personally, but I can't imagine it would be terribly difficult. In my experience, the Matrox device is remarkably resilient. http://www.matrox.com/graphics/en/products/gxm/th2go/guide.html

Actually, just looking at the Matrox website I found a PCI-e card that has 12 SDI outputs on it. http://www.matrox.com/video/en/press/releases/2014/sdi_cards/ibc/?ref=homepage

But I'm not sure why you'd want to output SDI to a CRT? That seems like a lot of front end tech for eventually signal degradation going from the digital to analog. 

Now the question is how much money are you willing to throw down?


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## FMEng (Sep 24, 2014)

Any monitor old enough to have a CRT (vacuum tube) display and BNC input, would require NTSC, not SDI. They use the same connector and cable, but the former is analog, the latter is digital (and more than half a century apart in development).


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## ruinexplorer (Sep 24, 2014)

While mostly true, there were reference monitors that would take SDI before CRT technology went with the dinosaurs. I agree that you most likely have an analog composite input with the BNC connector. This will require some translation of the signal through a scaling device.


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## MikeJ (Sep 25, 2014)

You can build a pc, and load it up with cheap graphics cards. Radeon 5450 or other low end cards will work fine, and can be had for sometimes $5 each. They only need 1-pcie lane even though they are in a 16x form factor. 
With 4 you can get 8 DVI/HDMI or 8 VGA, or a combination of the two. ***EDIT*** Qlab is Mac only isn't it?! Well this might be useful to someone else, but probably no useful for Qlab.**** 

Black magic also makes an 8 out sdi card, but most of these types don't have processing power.

The maxtor tripple head togo do work, I have run, I think 9 or ten outputs with the combination of a few video cards and the trippleheads, from one mac pro.

There are also options with programs like provideo player, you sync control of several different machines over the network, from one master, I'm not sure if Qlab offers that sort of control.


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## StradivariusBone (Sep 26, 2014)

If your end displays are analog, I'd try and find a splitter that outputs analog from the gate. The Mac will output the digital signal on their Thunderbolt (which is essentially DisplayPort which is backward compatible with VGA). The thing you've got to watch for is that Mavericks in my experience does not always play nice with analog video outputs. I utilize a setup with a Matrox TH2G feeding three analog projectors and one other USB->DVI->VGA adapter to feed an additional projector as a confidence display. 

After upgrading to Mavericks, that USB/VGA deal barely works. The new OSX apparently dropped some support for analog video output through USB adapters, so I would research that route before going too far. The Matrox boxes use ThunderBolt/DisplayPort to add the extra monitor and had no issues with the new OS.


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