Speakercon Posted March 9, 2012 Share Posted March 9, 2012 Hi, The basic scenario is a LCD monitor on the stage, which requires to be connected to a laptop at the back of the hall (to send the song lyrics down) and the only cables from the stage to the control area is the XLR snake, We don't want to spend a fortune, if worst comes to worst we'll just gaffer a long VGA cable round the room but I'd rather not if I can help it. I've tried sending a composite video signal down the snake (from a DVD player to a TV) and that works fine. Can anyone see a reason why this would not work. Using one of these http://www.ebay.co.uk/itm/160732238747? to convert the VGA out the laptop to composite, send that down the snake then use of one these http://www.ebay.co.uk/itm/220898958318 to convert it back to VGA to plug into the monitor. I know it's not allot of money wasted to try it and see but thought I'd ask anyway, encase I'm missing something obvious. Thanks allot. Link to comment Share on other sites More sharing options...
dbuckley Posted March 9, 2012 Share Posted March 9, 2012 The only thing I'd note is that this is a composite video quality connection (ie shit quality) and thus the image will be severely degraded compared to a VGA image. Only you can determine if the quality loss is acceptable in your application. You've tried it with a DVD player, so what you'll get at the far end of your link will look like the picture that came out of the DVD. Of course, you shouldn't be sending composite video down an audio multicore, but it can work; a video balun at each end to convert the video to balanced is recommended, and they don't cost much from anyplace that does CCTV. They typically have BNC at one end and RJ45 at the other, so buy a short RJ45 lead, chop it in half, determine which pair carries the video signal, and wire those to pins 2 and 3 on the XLR (using the same colour or core at each end!!!) leaving pin 1 unconnected. Link to comment Share on other sites More sharing options...
Speakercon Posted March 9, 2012 Author Share Posted March 9, 2012 Thanks for the reply, I know the quality won't be top notch, but as long as the lyrics are visible it doesn't really matter. I'll give it a go! Thanks for the balun idea! Link to comment Share on other sites More sharing options...
Matthew Robinson Posted March 9, 2012 Share Posted March 9, 2012 Why do you need to convert back to VGA? You could save money by converting to composite as you suggested above but then feeding the composite at the other end of the multi straight into the TV. Link to comment Share on other sites More sharing options...
Speakercon Posted March 10, 2012 Author Share Posted March 10, 2012 Why do you need to convert back to VGA? You could save money by converting to composite as you suggested above but then feeding the composite at the other end of the multi straight into the TV. Thought about that, but we don't have any LCD TV's to spare, but we have a room full of monitors! Link to comment Share on other sites More sharing options...
Matthew Robinson Posted March 10, 2012 Share Posted March 10, 2012 Alternatively, a VGA balun? I've seen some for cat5, but I don't know how many of the cores they use. Use David's idea of getting cat5 to XLR (although you may need more)? Link to comment Share on other sites More sharing options...
paulears Posted March 10, 2012 Share Posted March 10, 2012 As it's quite common to do VGA to component, on a VGA to phono cable, couldn't you just break out the VGA to a number of unbalanced connections, squirt that down the multi and the reverse the connections at the other end to give you a VGA connector. Impedances would be a bit random, but wouldn't this just enable the VGA to stay VGA? Link to comment Share on other sites More sharing options...
Owain Posted March 10, 2012 Share Posted March 10, 2012 run an ethernet cable to the stage, put a Rasp Pi with a VNC client at the stage end to mimic the laptop screen. or substitute a cheap 2nd laptop if cannot wait for Rasp Pis to become available. Or use wifi and not need the ethernet cable. Link to comment Share on other sites More sharing options...
mac.calder Posted March 10, 2012 Share Posted March 10, 2012 run an ethernet cable to the stage, put a Rasp Pi with a VNC client at the stage end to mimic the laptop screen. or substitute a cheap 2nd laptop if cannot wait for Rasp Pis to become available. Or use wifi and not need the ethernet cable. If the OP is willing to run cat5, just use a VGA->Cat5 balun. One step better would be an active VGA->Cat5 system. Link to comment Share on other sites More sharing options...
Speakercon Posted March 10, 2012 Author Share Posted March 10, 2012 As it's quite common to do VGA to component, on a VGA to phono cable, couldn't you just break out the VGA to a number of unbalanced connections, squirt that down the multi and the reverse the connections at the other end to give you a VGA connector. Impedances would be a bit random, but wouldn't this just enable the VGA to stay VGA? Tried that, by chopping a VGA cable in half and fitting XLR plugs and sockets to the 6 cores (2 per XLR + ground), it worked but the picture was unreadable so it must have been picking up interference from somewhere. Also tried that with 2 of these http://image.made-in-china.com/2f0j00CMNQRvUPbIce/VGA-to-RCA-Plug-Cable.jpgwith XLR - phono adapters, the results were pretty much the same. Its funny though it worked fine when connecting the cut VGA lead it to a 20m role of 6 core alarm cable with no twisted pairs or sheaving. Hmmmm If we had cat5 links from the stage to the control area that would be great (Add that to the list of things to do next time we get the opportunity) but we don't so if we were running that round the room we mers-well just use a VGA lead. So many problems! Link to comment Share on other sites More sharing options...
smalljoshua Posted March 10, 2012 Share Posted March 10, 2012 I'd just pull a half dozen lines of Cat5E Cable in. The flexibility gained in doing that will out weight the time spent doing it. Did you try putting baluns on the Lines once you split it out into the RGB? Also, did you try splitting it to RGBHV then putting Baluns on it from there? Josh Link to comment Share on other sites More sharing options...
Speakercon Posted March 13, 2012 Author Share Posted March 13, 2012 No I did not use any baluns, didn't think about it tbh! Yeah lots of cat 5 would be useful, its a bit tricky though as there's no loft space so concealing cables is difficult. Link to comment Share on other sites More sharing options...
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