Newsgroups: sci.engr.television.advanced
Subject: Re: Are component video cables same as RCA
References: 
"Normand Peladeau"  writes:

> I would like to connect my new TV set to my DVD player using Component
> cables.  The price for those cables are rather high and I was wondering
> whether I can use standard RCA cables (actually they are spare Monster
> Cables I have purchased for my audio system).

The proper cable for transferring video signals is 75 ohm coaxial
cable. It is the right cable no matter if you transfer composite
video, S-video, component video or RGB. In all those systems the 
picture components are designed to travel through their own
75 ohm ciaxial cable.

If you put video signal form video equipments to something else 
than 75 ohm coaxial cable, you get an impedance mismatch which
will caus signal attenuation and signal refelections, which
decrease the picture quality more or less (depends on signal
frequency, amount of impedance mismatch and cable length).

Typical RCA audio cables are not designed for any particular impedance,
and their impdance can vary from soemthing like 40 to 200 ohms depending
on the cable construction. Typically those impedances are in 50 ohms
to 100 ohms range. The fact is that if you just pick any RCA cable,
it is very propable that is more or less off that 75 ohm impedance
and so cause signal reflections to the system. For video signals for TVs
at distances of 1-2 meters you do not usually see any difference if
you use use normal audio RCA cables, but at long distances you will
most propably see (in rare good cases RCA cables can work quite
nicely, but in most cases not).  75 ohm cable is the sthign which will
work for sure, no matter if distance is few meters or more than 10 meters.

If you are buying or building cables for any more than few meters distance,
my advice is go to 75 ohm real video cables. Unfortunately some shops
seem to chage horrible prices on this kind of cables, which should
not cost any more than any decent quality audio cables with 
RCA connectors (materials cost for both cables about the same,
so does the manufacturing). if your shop is charging outgorgously
high prices for you cables, try some other shop, there should be
cheaper ones. Check places which sell profession video accessories,
because form this kind of places you can find both good selection
of good quality cables that prices which can be much cheaper than
thing in hifi shops. To my knowledge Monster Cables are quite expensive
audio cables, and using them for video applications sounds to me like
waste of money because they are most propably the most suitable
cables and you shoudl be able to get right 75 ohm cable from less
money than many Monster Cable models I have heard about. 

If you are building cables yourself, you can get both good quality
audio cable material and 75 ohm coaxial cable for about $1 per meter
(or even less). RCA connectors cost typically $1-2 per connector
(very good ones somewhat more). Those are the prices of those
components in shops which sell electronics components. 
I buy my video cables either as components or ready made from
my local electronics shops here in Helsinki Finland  (the best 
place for this kind of components are www.yeoy.fi and www.partco.fi).


-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/