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So how does this differ from using RG6 cable ...
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I assume you are talking about CATV grade RG6? The often-recommended Belden/Canare cables from the custom sites almost all use RG6 form-factor.
But just being "RG6" does not tell you the coax is built for video frequencies.
Here is how engineers pick coax for an application:
- Determine the maximum frequency signal you will send. For this example, let's pick
35 Mhz for 1080 video.
- Multiply the max frequency by 2 and 4 to give you an acceptible range. For our example, this would be 70 - 140 Mhz.
- Now look at the specs on the Belden or Canare web site and select a coax that has
less than 3 db drop over 100 feet of coax.
Belden gives tables of numbers, but Canare has a nice chart:
Look at the horizontal line that indicates 3db of "attenuation" (attenuation = reduction)
The V-5CFB hits the 3db line at around 250 Mhz. - This coax would work well for 1080 video.
The V-4CFB and V-3CFB both hit the 3db line at about 150 Mhz. The V-4 would be a better choice as it hits a bit higher.
CATV Coax - Before you just go down and buy RG6 coax from the local store, remember that CATV signals only go to about .. 1 Mhz. Component video goes up to 4 Mhz, let alone Progressive or 1080. See the roll-off in the Canare graph? The hardware-store RG6 coax will look much worse than this in the 1-35 Mhz range.
Yet, it will APPEAR to work. There will be a loss of focus because the higher-frequency signals are rolled off, but you will "see" video. This is why the rumor that any-old RG6 coax will work came about.
Note: People will say that some CATV coax is rated to the GigHz range for Sat/cable modems. But these signals are DIGITAL so they are a lot more robust/forgiving of the cable. Dont buy coax rated for 1.1 Ghz digital and then assume it works for 35 Mhz analog. Read the fine print.
The other issue: the RCA connector.
Think of the RCA plug as a "speed-bump". You really want to get a RCA plug that as closely matches the 75 ohm impedence of the coax. While it's impossible to exactly match this, some RCA plugs like the Canare plugs come darn close.
The generic RCA plugs from Radio Shack - could be 30 ohms, 50 ohms, 90 ohms... etc. Audio is NOT sensitive to the impedence like video. Try to find RCA plugs with impedence ratings, or any verbage like "Component Video" or "HD Video" compatible.
The Price: See the Canare graph? See the really good V-5CFB coax? How much WOULD you pay?
$5.00 /ft
$4.00 /ft
But wait. If you call now, you can buy this 3-conductor, HD Grade RG6 coax for:
$1.52/ft
This is what production studios/broadcast stations pay.
(Yes, they have to buy spools of 300 feet at a time.)
If you have long runs, contact the custom web sites. They will likely charge you more than the bulk price (because there is storing, cutting, measuring, handling involved), but you WANT them to put the good Canare RCA plugs on the ends (the tools cost about $300 to do it right).
A cable made with this stuff will rival/beat the Monster CX-300 component cable set that sells for $220 for 6 feet.
