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RGB Scart to Component ??? HELP!!!

Discussion in 'Cables & Switches' started by MAD ANDY, May 9, 2005.

  1. MAD ANDY

    MAD ANDY
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    Hi all

    I currently have a Panasonic SC-HT70 DVD player with scart, S-Video and Composite video out. I also have a Sanyo projector with S-Video and component in.

    I was originally advised to buy a composite cable to connect to the pj which I did - then found out composite was the worst possible video cable and to upgrade! As I dont have component out on the DVD player, I have been looking for a s-video to s-video cable... then I found this:

    http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=11073&item=5763245029

    I have just bought some Thomson RGB scarts for connection between the DVD-TV and Sky-TV, and the seller of these mentioned he didnt believe the RGB scart to component cable would work properly, just after some advice as to whether this is correct or not, just on the basis that if the cable has been made, what use is it if it dont work?

    If the cable above is no use, the choice after that is one of these two:

    http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=67859&item=6765798018

    http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=32837&item=5763222984

    Confused on the second one though as the seller mentions 'sound' - thought s-video was for video only?

    TIA

    Andy
     
  2. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    S-VIDEO only carries picture so the comments about sound are pretty pointless.

    The RGB to component cable will not work.

    You want an RGB to YPrPb convertor if you are after what should be your highest image quality. www.rgbtosvideo.co.uk John Sim does one. Then get three RCA to RCA video cables from it to the PJ.

    Alternatively get a quality s-video to svideo cable (will cost you less and will give miles better quality than composite)

    Gordon
     
  3. MAD ANDY

    MAD ANDY
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    Gorden

    cheers for the reply. The company who make the cable seem to have a reputable site: http://www.clicktronic.de/products.php?language=en so not sure what the use of it is for if what you say is correct.

    I'll stick with the S-Video option though, out of the two I put in the post above, do the spec of them seem good enough? Especially the second?

    cheers
     
  4. severnsource

    severnsource
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    I think your cable sellers descriptions are being a bit confusing, which isn't helped by the vagueness attached to the term "component". Strictly speaking any form of connection which isn't composite can be called component, e.g. RGB is component, so when the dealer says component he means RGB components.

    However component generally implies colour difference signals, that is luminance (Y), R-Y and B-Y. In order to generate colour difference signals from RGB you need electronics, a passive cable can't do it, so as Gordon says you either need a convertor box or make do with an s-video cable, which should give pretty acceptable results.

    If your projector has a vga input it may be possible to use a SCART to vga cable as I do with my Sanyo Z1.

    I think the sound references are just bad copy checking.

    Bill
     
  5. MAD ANDY

    MAD ANDY
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    cheers for the reply severnsource

    interesting what you say about the VGA, as my Sanyo pj does have a VGA input, however I need a 15m cable, which I'm assuming isnt an issue due to the length of VGA cable run in offices for ceiling mounted pj's etc, but is it ok to run this distance with scart at one end? and if so, would this be better than s-video?

    cheers
     
  6. severnsource

    severnsource
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    The distance shouldn't be a problem as long as the cable is good quality, but I think my suggestion about the VGA input is probably a red herring.

    The signals from a PCs VGA output are slightly different from those on a SCART connector. My (home cinema oriented) Z1 has the option to switch between PC standard and SCART standard on its VGA input. As your projector appears to be a data projector I doubt that it has this capability and probably won't work properly with this sort of connection.

    Bill
     
  7. MAD ANDY

    MAD ANDY
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    ah ok :(

    on that basis, out of the two S-Video leads I have listed above, which would be your recommendation?

    or do you think these are nothing special and could recommend a lead around a similar or cheaper price?

    cheers
     
  8. severnsource

    severnsource
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    Sorry, it's impossible to make a realistic assessment, because those descriptions don't give enough meaningful information about the cable.

    Apart from the length, the only useful comment is that the cables are foil and braid screened, which is good and implies that the quality of the cable should be OK. Assuming that the cable is OK either of them should do the job, I would just choose the shortest. As far as I can see the prices look about par for the course.

    Bill
     
  9. MAD ANDY

    MAD ANDY
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    Bill

    cheers for looking, on the opposite scale, what info would you say made the best cable so that I can look for one of the spec you recommend? and why choose the shortest cable? does s-video get affected by distance?

    cheers

    ---
    edit:

    Bill, I've found this cable now which I'm very interested in which has the bits on to reduce interference, how does this one look (unfortunately doesnt come in a 15m option which is the minimum I need hence having to look at this 20m option)

    http://www.audiovisualonline.co.uk/dynamic/eshop_products.set/ref/315/display.html
     
  10. Joe Fernand

    Joe Fernand
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    Hello MAD ANDY

    Here's info on our best selling S-Video cable - compare the specs with anything else your considering and note that distance does play a part in S-Video signals.

    See http://www.bettercables.com/15me4febecas.html

    If these are outside your intended budget go to the 'Cable Power Buy' section of the AV Forums and order an S-Video cable from Mark Grant; again very high quality and miles better than the cables your considering.

    Best regards

    Joe
     
  11. severnsource

    severnsource
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    The requirements for a good video cable are simple, and they are the same whatever signal is going down the cable, composite, RGB, component of s- video.

    Cable impedance should be 75 ohms.
    The cable should have good screening, foil and a dense braid will give very good results.
    It should have a reasonably low loss dielectric.
    Copper is the best conductor for the inner and the braid.

    The connectors should have the correct size pins and not fall apart when connected or disconnected.
    Tin or nickel are perfectly acceptable materials for the pin contacts, a good thick silver coating is probably the best but isn't significantly better under domestic conditions than the cheaper materials. Gold is just a marketing ploy.

    I am afraid that I can't tell you which cable to buy. As a rule retailers descriptions don't give any meaningful information and I don't have experience of the multitude of cables on the market. However I would expect that any of the cables that you have pointed out will work acceptably well, any significant problems with poor impedance matching or screening failures will be readily visible and you can return the cable as unsuitable for its purpose if you buy from a UK dealer.

    While I have no doubt that Joe Fernands cable works perfectly well it won't work any better than a properly made cable at a quarter of the price.

    The reason that I mentioned length was that it seemed to be the only significant difference between the cables. Coaxial cables have frequency dependent losses which are proportional to cable length, so the longer the cable the more HF loss is possible. However, if you have used decent cable in the first place there should be no significant visible losses with the relatively low frequencies and short distances involved here. Also shorter cables have less exposure to interfence if your environment suffers from a lot of that. But the difference between a 15M cable and a 20M one will be very small.

    Bill
     
  12. Joe Fernand

    Joe Fernand
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    Hello Bill

    If someone can produce a cable for £0.01 that was 'properly specified and constructed' then as you say it ought to be as good as our BetterCables cables.

    The problem now is folk will grab on to the 'quarter of the price' line and believe our cables are overpriced - yet as you say you don't know of any properly constructed cables that are a quarter of our price :)

    Our cables are all provided on a Sale or Return basis and we don't get many back.

    15m is a long cable run for the majority of Consumer source kit to 'drive' and the cable you use will play a significant part in what you see on your Display.

    Keep in mind MAD ANDYS using a projector + screen not watching a 14" portable - any image flaws are going to be very apparent.

    Best regards

    Joe
     
  13. MAD ANDY

    MAD ANDY
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    Gents

    your input is very valuable and I very much appreciate your time here! :)

    Joe - I would be more than happy to try the cable, but at $129 its way over my budget I'm afraid :( sounds like the one for the job though, can you do it for £30 delivered ;)
     
  14. Joe Fernand

    Joe Fernand
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    MAD ANDY

    Not unless I want to lose some money :)

    Up the budget by a fiver and a 15m VanDamme Red Series is on the cards - we use these on lots of installs where were running S-Video at 10m+ and get good results; though as before at 15m you are relying on your Source kit to have a decent signal on its S-Video output socket.

    The VanDamme Red Series S-Video is a Twin 75ohm OFC cable with moulded plugs.

    Best regards

    Joe
     
  15. severnsource

    severnsource
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    This is completely meaningless. It doesn't matter if the cable is 5cm long or 5Km, the requirements of the source are exactly the same.

    Video signals are sent along impedance matched transmision lines, they are fed from a 75 ohm source impedance into a 75 ohm transmission line and terminated by a 75 ohm load. As long as the soiurce can feed a 75 ohm load correctly the cable length is irrelevant.

    Bill
     
  16. Joe Fernand

    Joe Fernand
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    severnsource

    I'm sure from a technical point of your very correct - me I deal in real world installations and If I stick a 15m S-Video cable into the back of the majority of 'Consumer' kit I get a B&W or colour smeared image up the far end on the customers TV.

    Using a properly engineered cable ensures the cables not going to cause problems but I have no way of guaranteeing someone's £50 DVD player is anywhere near proper spec; talk to John Sim at JS Technology I'm sure John will be happy to discuss how much kit is out of spec and how much time he spends customising converters to work with wayward source kit.

    I'd love to 'see' you plug 5Km of cable into a DVD player and get an image at the far end :)

    The VanDamme Red Series cable I mentioned earlier is a properly specified cable yet the manufacturer advises its use at 20m max - quite a way off of your 5Km!

    Even if we add an S-Video line driver into a system were looking at 50 to 100m max depending on what Line Driver we use.

    Real World and Technical Correctness are not often one and the same thing I find!

    Best regards

    Joe
     
  17. hornydragon

    hornydragon
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    impeadance matched is very good but copper wire will not transmit 100% signal power over an infinately long cable......Impeadance matching reduces reflected signals but doesnt make the medium lossless.
     
  18. severnsource

    severnsource
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    Yes, I am well aware that cable is not lossless, what I was commenting on was Mr Fernands claim that the results at the far end of a 75 ohm cable depend on the "quality" of the sending device. If the sending device has a properly implemented 75 ohm output video amplifier, then the signal at the far end of the cable will be the same regardless of the originating equipment. These days it is trivially easy to design good enough video amps and I would expect the cheapest equipment to have acceptable amplifiers.

    Bill
     
  19. hornydragon

    hornydragon
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    Bill unfortunately many major manufacturers dont find it a trivial matter. :rolleyes:
     
  20. Joe Fernand

    Joe Fernand
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    Hello all

    Bill, Joe suffices most of the time :)

    I think your arguing with yourself on this one - you say if the source is technically correct and the cable is technically correct then the Input signal will arrive intact at the far end of the cable; which seems reasonable enough.

    I say the majority of kit is far from perfect (its all built to a price) and even if the cable is perfect your not guaranteed a decent signal on the end of a long cable.

    If your designing a DVD player to a price and you have the option of an output amp designed to drive 1m of cable and a more expensive output amp designed to drive 20m of cable which one do you include in your design - bearing in mind 99% of your paying customers use 1m cables?

    Best regards

    Joe
     
  21. MAD ANDY

    MAD ANDY
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    I run a Panasonic SC-HT70 DVD player, how can I tell if the S-Video is outputting at 75ohms?
     

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