Newsgroups: rec.audio.tech Subject: Re: Cabling question - Please help References: <[email protected]> Samwrites: > I would appreaciate hearing from anyone with an opinion on the > following: > > On a 25' run of S-Video connection, are we better off using a quality > S_video cable or using two quality RCA cables with Y/C splitters/ Is > there a difference? Avoid "RCA cables" and "quality RCA cables" at any long run video. Those RCA cables usually have the shielding made quite well, but their characteristic impedance can wrong for video and their high frequency losses can be high. Using cable with wrong characteristic impedance is like asking for cable signal reflections to mess up your video signal quality. Using cable with high losses at high frequencies (several MHz) will cause loss of high frequency picture details (=smears picture). Those reasons are why you should always use good quality 75 ohm coaxial cable to carry video signals. Those cables has the right impedance and low losses at high frequencies. And using proper 75 ohm ciaxial cable is no more expensive than "quality RCA cables", in can easily be a lot cheaper than high price "hifi RCA cable". Using right cable can save you the picture quality and some money! Running S-video-signal takes two 75 ohm coaxial cables. One of them carries Y signal and other carries C signal. This is how all good quality S-video interconnections are made. A S-video cable has two miniature 75 ohm coaxial calbes inside one outer cable jacket. This cable works well in typical video applications up to 10-15 meters very nicely (maybe longer distances). On some longer distance applications the signal is usually carried over two thicker 75 ohm coaxial cables (thicker cable = less losses). When using two separate calbes, usually an adapter cable which adapts the tine 4-pin S-video connector to two BNC connectors is used on the both ends of the connection, because it is hard to put two thick cables to a miniature 4-pin S-video connector. Both of those coaxial cable alternatives are usable in your case. > In component video on a 25" run, are we better off using a quality RGB > cable or running 3 RG quad shield coaxial. Bot options are are usable. Those RGB cables are just three (or more) 75 ohm miniature coaxial cables inside on outer kable jacket. Those cables work in practice wery well. The performance is the same as using three separate thin coaxial cables. If you use three separate thicker 75 ohm coaxial cables, you can get somewhat lower losses if you select the cable carefully. > How much audible difference is there to comoon ears between exotic RCA > or optiical cables connected to a quality audio receiver rather than > common interconnects. There is no consensus what is the difference between exotic cables and normal interconnection cables. Some people claim to hear the difference, most people do not (at least at short interconnects). In analogue interconnections the cable type and equipment connected to them can have even noticable effects. If you have a sound source has high output impedance (few kohms) and you have a long high capacitance cable, you could hear some losses in hifh frequencies. In this case the problem would be corrected by using low capacitance cable or using sound source with lower output impedance to drive the original cable (other sound source with low output impedance or suitable distribution aplifier between sound source and the cable). If using en exoctic RCA cable makes difference in the first case, depends on the cable, because an exotics cable is for sure expensive, but in use it's quality can be "good" or "bad". For digital interconnections (S/PDIF / IEC958) a good 75 ohm coaxial cable is the cable type to use (the same cable as for video). Using exotic cable does not help here in any way to give better performance than "average good" coaxial cable. For optical interconnections any proper quality a 1 mm plastic fiber with "toslink" type connectors will do. Using some exotic high price cable does not give any benefits compared to any "average good" cable. > Thank you in advance for your answers and feel free to email: > [email protected] -- Tomi Engdahl (http://www.iki.fi/then/) Take a look at my electronics web links and documents at http://www.epanorama.net/
