[mythtv-users] coax vs. composite

[Brian Wood]

On May 15, 2006, at 6:45 PM, Robert Johnston wrote:

> On 5/15/06, Brian Wood <beww at beww.org> wrote:
>> If it hasn't been made clear (I just had 63 messages in my inbox and
>> may have missed a few):
>>
>> In home consumer systems:
>>
>> RCA connectors are used for composite video, and are also used (in
>> groups of three) for component video.
>>
>> When used for composite video they are sometimes color-coded yellow,
>> and when used for component video they are sometimes color coded red,
>> blue and green.
>>
>> They are also used for unbalanced audio, and when in this service
>> they are sometimes color-coded red and white.
>>
>> RCA connectors are also sometimes (not very often these days) used
>> for RF signals in radio receiver systems.
>>
>> An RCA connector is probably the worst connector ever designed (IMHO)
>> for either video or audio. They have no real "nominal" impedance, are
>> difficult to solder properly, make the "hot" connection before the
>> ground (thus rendering audio systems susceptible to loud hums and
>> pops). The provision for strain-relieving the cable is poor to non-
>> existent and they tend to get noisy easily. They depend on friction
>> to "lock" the connector in the socket. Whwn used in audio systems
>> they make no provision for keeping left and right oriented properly
>> (except for color, if that's used correctly,which is rare).
>>
>> In short, they suck. Why are they used? You can guess that, they are
>> cheap.
>
> Hand-wired Balanced XLR3's all the way... For Audio, anyways (Though
> some would argue you should be using ST Fibre Optics).
>
> For Video (Or more accurately, A/V) we SHOULD be using RGB over SCART
> (Or "Péritel" in France).
> --  

I agree, for a small number of audios an XLR( Cannon), also known as  
A3M/F (Switchcraft) connectors, also known as "QG" for "quick  
ground" (look carefully at the female connector and you will see that  
pin 3 comes out just a bit further than the other 2, so the ground  
will "make" first).

Of course when you get to many many audios that many XLRs get a bit  
unmanageable.

For video here in the US, BNCs are pretty much the standard now,  
though I remember when "UHF" connectors were used (PL-259/SO-239),  
those are pretty much used only for RF nowadays. Interestingly,  
although they were called "UHF" they were never certified for  
anything above VHF frequencies).

UHF connectors were better for video in some ways, especially on  
remote trucks, where they were often getting pulled, tripped over  
etc. The UHF connector held tighter than a BNC. Both BNC and UHF  
connectors were a pain to make, though nowadays crimp-types are used  
as opposed to the "clamp and solder" original ones.