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upgrade component and s-video with BNC?


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4 replies to this topic

#1 of 5 OFFLINE   Craig Aguiar

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Posted January 05 2005 - 07:48 AM

Hey all. I read an article online where the writer states that if you remove the S-video connectors on your cables and hardware and replace them with BNC connectors (soldered to the PCB, not using adaptors) then you can significantly increase the picture quality. He even stated that it would be better looting than RCA component video (non progressive). Can anyone confirm that? Next then, if I replace my RCA connectors with BNCs will that improve my component video picture quality? Thanks, Craig

#2 of 5 OFFLINE   Bob McElfresh

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Posted January 05 2005 - 04:06 PM

I'm not sure it will "significantly" increase the picture quality.

Look, the BNC connector IS superior to SVideo or RCA plugs because it keeps the center wire rigidly in the middle of the shield. This, and the locking ring, is why most professional gear use them.

The signal advantage is it maintains a uniform 75 ohm impedence.

Think of your video cable as a pipe that you are shoving water through. At the end, the pipe suddenly goes through an adaptor that makes the pipe ... 15% smaller. Water flowing through the pipe will hit this restriction, bounce back a bit, cause disruption in the flow, etc.

In a video cable with crappy SVideo or RCA plugs, the higher-frequency signals will "hit" the plug and reflect in the cable. This causes a slight "ghost" image and a loss of some finer-grain detail.

The BNC connector could remove an artifact from a low-end component video cable, but not really improve the video quality.

It MIGHT improve a SVideo signal more because instead of running two thin wires twisted together, you would be using 2 separate runs of coax cable.

So cutting the ends off of your cables and installing BNC jacks IS a good thing, but you need to do it at both ends.

The other problem is: it takes an experienced electronic tech to correctly solder the connections to try and make sure the spacing is uniform on the solder, things are clean, etc. It's not for the casual user.

I build my own RCA video cables, but I wont try to build a SVideo cable for the same reason. It takes an experienced hand to keep the twists in the cable, and do a neat solder job on that tiny plug, etc. I'd go to someone like www.bluejeanscables.com for this or a custom HDMI cable.

Does this make sense?

#3 of 5 OFFLINE   KurtBJC

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Posted January 06 2005 - 06:46 AM

There's a small theoretical advantage because you'll get a better impedance match with the BNCs than with s-video or RCA type connectors--but really, the length of the impedance mismatch is so short that it's very unlikely to matter in any perceptible way. I love BNCs--but I sure wouldn't want to spend the time de-soldering all the RCA and s-video terminations on my gear.

#4 of 5 OFFLINE   Chu Gai

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Posted January 06 2005 - 08:25 AM

A pity the online writer didn't take pictures to substantiate things. I'll toss my hat in with Kurt and Bob.

#5 of 5 OFFLINE   Craig Aguiar

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Posted January 08 2005 - 04:07 PM

I do alot of soldering so I'm pretty confident I could do a very clean job. And I understand I would have to do both the source and the display. I would run two runs of decent coax and turf the S-video all together. Anywho, I think I agree with you guys. I was skeptical as well, otherwise people like us would have done this from the first day JVC introduced S-Video. Maybe if I'm bored one day I'll do a satelite receiver as I have the parts lying around. Until then I have better things to do. Thanks for the input Craig




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