Coax vs Cat6 for long component run?

[tiberiust]

Good day all,

My Sky+HD box is abt 9 metres from my PC with my shiny new Blackmagic Intensity inside. I’ve been disappointed with the encoding artifacts from the Hauppauge HD-PVR recordings so decided to upgrade (I archive mainly HD nature programmes for my HTPC with x264 and Avisynth).

The only way to get the HDMI working would appear to be the prohibitively expensive HD Fury, so it’s component time from my Thomson box which is close enuf in quality (just) to HDMI when viewed on the TV with good 3 meter component cables.

I suppose that decently shielded Coax would be the best quality bet, but 3 cables will be bulky going around the side of the room and ‘her who must be respected’ has issues (also the reason the PC is so far away from the Sky box!). It’s easy to solder RCA connectors to Cat6 pairs, but frankly the cables just look…’weedy’ and I’m not sure it’s gonna be good enough. Obviously trial and test is the correct way to go but there’s some effort and expense involved setting up both, only to dump one in the bin.

So, I wondered whether anyone here has any opinions or comparative experience?

Tks in advance anyone

T

 

[Joe Fernand]

How long is the required cable run? Joe

 

[tiberiust]

How long is the required cable run? Joe

Hi Joe. It's about 9 meters. IOW I suppose I could buy a 10 meter component cable but I'm always dubious of the quality of manufactured analogue cables hence I often use good coax then an F-Plug to RCA connector. Then there's the size issue of the cable again - I guess what I'm really asking is : Is Cat6 going to be good enough?

Tks
T

 

[noiseboy72]

Cat 6 is a balanced line cable, so you will need to use baluns at either end to change the 75 Ohm unbalanced component signal to a 600 Ohm balanced line.

At HD, this will need to be active rather than passive transformers as these will not have the required bandwidth. Expect to pay £200 for anything worth having.

A tidier option would be a good quality VGA HD 15 cable and a set of breakouts to RCA or BNC. VGA cable has the correct impedance cable and the connectors should be of good quality as well. Certainly better than using F-Plug to RCA.

 

[Joe Fernand]

VanDamme Red or Mini Red Series (4 core) can be supplied pre terminated with RCA at your required length and will work a treat – OD is 18mm (Red Series) or 8.9mm (Mini Red Series).

As noiseboy72 says ideally you’ll want Baluns when using CAT5 or CAT6 – though I have seen posts from folk doing what you describe saying its OK (though not sure how large a Display they were feeding).

Zektor

Joe

 

[tiberiust]

Cat 6 is a balanced line cable, so you will need to use baluns at either end to change the 75 Ohm unbalanced component signal to a 600 Ohm balanced line.
Expect to pay £200 for anything worth having.
A tidier option would be a good quality VGA HD 15 cable .

Ah!...Once again I seem to have reached a knowledge limit . I've read about people running Sky+ to TVs in other rooms using long runs of Cat5 or 6 based component - I merely assumed the signal quality would be fine. Your suggesting that it certainly won't be optimal?

As noiseboy72 says ideally you’ll want Baluns when using CAT5 or CAT6 – though I have seen posts from folk doing what you describe saying its OK (though not sure how large a Display they were feeding).
Joe

So you both agree that baluns will be required then? I'll see if I can find some quality VGA cable, that seems to be the most economical solution. Can yu give me some pointers as to what type of VGA cable to look for - or is ''the thicker the better'' any sort of guide?

FYG I live in Greece - not much here in the way of cable shops, hence my DIY mode

Tks very much to both of you for your guidance.

T

 

[noiseboy72]

Yep, thicker the better, and with good quality plugs. The main issue with most cabling is the connectors, not the cable. ghosting and picture instability is normally caused by reflections from poor connectors or plugs and sockets of the wrong impedance.

The reason why Naim and Quad used DIN plugs not RCA was beacuse they are the correct impedance for the cable. 75OHM BNC would be the best.

 

[tiberiust]

@Noiseboy72

Tks again. I'll buy one of those 10meter VGA cables from e-bay , chop it and solder RCA connectors on. The Blackmagic Intensity Pro has RCA inputs so gotta be really. I'll compare it against the HDMI b4 I use it and report back if it's not acceptable.

Cheers

T

 

[Alan Mac]

Re: noiseboy72 posts 4 and 7:

QUOTE:
“Cat 6 is a balanced line cable, so you will need to use baluns at either end to change the 75 Ohm unbalanced component signal to a 600 Ohm balanced line”

Category 6 cable has a nominal characteristic impedance of 100 Ω (not 600 &#937.


QUOTE:
“The main issue with most cabling is the connectors, not the cable. ghosting and picture instability is normally caused by reflections from poor connectors or plugs and sockets of the wrong impedance.”


http://www.avforums.com/forums/inte...s-switches/1281394-digital-coaxial-cable.html

See my post 15 and Return loss:75 JPG
The measured return loss (in the 75 Ω test system) for the RCA-phono connector was better than 26 dB at frequencies up to 50 MHz.

So we may conclude that RCA-phono plugs and sockets are perfectly adequate for HDTV base-band use.


QUOTE:
“The reason why Naim and Quad used DIN plugs not RCA was beacuse they are the correct impedance for the cable. 75OHM BNC would be the best.”

Quad and Naim used DIN plugs and sockets for AUDIO frequencies.

Unless the cables are many kilometres long, impedance matching is of no relevance at audio frequencies.


Alan