Dull question about RCA/Componant cables

[Eirik]

Hey all,

I've usually found this to be a good source of information for off-the-wall tech questions since a good many folks here are much brighter than I about tech stuff.

I'm shortly going to be running wire through the walls in my home in order to neatly mount an LCD TV and run the wires about ten feet to all the various bits and pieces of my A/V system. I'm going to install wall jacks to make it all look much neater and easier to change connections when needed.

What I'm finding is that I can fairly cheaply run RCA wire though the walls, but my only obvious solution to running digital componant is a couple of rather expensive cable systems that all have to be ordered over the internet.

But by my eye, and what I've been able to gather online, the only real difference between decent quality RCA (RWY) and digital componant (RGB) is the colors of the jacks. If that's the case, I'd far rather do that and just mark the colors next to the jacks.

Does anyone know if I'd lose any real quality by doing this? Any advice would be much appreciated.

[SeanF]

Eirik, my understanding is that this should work okay as long as you get good quality composite cables. Sometimes the red and white cables in the composite set are of lower quality, since they're intended only for audio, and can cause problems. But as long as they're good quality cables, they should be able to handle the component signal just fine.

The other thing to consider, of course, is that if you want to run component video and audio, you need five cables - not the three of composite. :)

[yuzuha]

"digital" has become a marketing term used as an excuse to jack up the price of wire. i.e. I saw a "digital" subwoofer cable that was huge and fat so it looked like it could really carry those powerful bass notes.... much to the annoyance of the person trying to sell it to me, I unscrewed the rca plug cover and low and behold it was 22 awg twisted pair inside a hugely thick jacket (well, at least it was well protected twisted pair). A true "digital" cable applies to cables designed to carry digital sound signals between components that have optical or electrical transmitters or recievers. The electrical ones are supposed to have a 75 ohm characteristic impedance for use with 75 ohm coaxial cable (despite the fact that rca plugs have a characteristic impedance of about 35 ohms). Now composite and component video cables are also 75 ohms and carry a signal between 5 and 10 MHz, and will carry digital audio just fine.

If you are running it in the wall you probably want plenum cable in RG6 or RG59. RG6 generally has a foil shield and is good for satellite and cable television signals and is usually pretty stiff. The RG59 is generally has copper braid only and is a bit more flexible so makes better component/composite video and digital audio cables so you're looking at something like Belden 1695a or 89259 cable (electrical / fire codes do not require metal conduit for plenum cables). Ram or bluejeans or several other places can make up cables for you or you can make your own if you can find a place that will sell it in less than 1,000 foot rolls. Those are top of the line teflon cables that will run at least about $1.30 a foot so there are much cheaper alternatives.

search on "bundled rgb cables" (bluejeans also has these). These are color coded mini coax snake cables bundled in a single outer jacket and generally carry between 3 and 5 cables inside them.

[mugaliens]

The information contained in RCA is poor, as it's heavily mixed and transmitted over a single pair of wires. The information contained in Component Videos is very noticeably much greater, and it transmitted over three pair to isolate the various color information.

Go with the component option!

I've compared both, with numerous movies, and the component video option has, every time, produced a vastly superior pircture.

Expect to spend between $30 and $70. You'll be very glad you did.

[farmerjumperdon]

No expert on the specs or whys, but just my experience as a user - definitely go with component video. Noticably better than the RCA. Never used S-Video connections, and none of my components have the DVI thing I'd heard about last time I was shopping for AV equipment.

[SeanF]

Just to clarify something here. Eirik is not asking about the difference between component and composite signals. He is just asking if there's a physical spec difference in the cables that are sold as "component" cables versus those sold as "composite" cables.

[lek]

Should suggest that if you are breaking walls etc for a cable, add in one normal optical cable while you are at it. You might be grateful for that next time you upgrade your stuff...

[yuzuha]

All of them are essentially RG59 or RG11 (this is fat cable about 1/2" that is generally used in tv studios where cables get a lot of abuse). Granted, there are different versions of these... a home video cable isn't going to need the same low loss or high frequency characteristics as a microwave transmitter cable, but you probably want something a bit more substantial than the micro-mini coax that comes packed in with your dvd players and the like.

But, essentially the only difference between a good quality composite video cable and a digital audio cable is the word "digital audio" on the package, and the only difference between it and and a component cable is the component cable has 3 lengths of the same cable bonded together with fancy color coded plugs. If you don't mind doing a little soldering, you can save quite a bit by buying a bulk roll of high quality RG59 and making all your own cables. (you can even make speaker wire out of it http://www.tnt-audio.com/clinica/ubyte2e.html

[mugaliens]

Or, better yet, just use WinDVD and watch it on your home computer with high quality sound and video cards, a good monitor, and a pair of studio-quality headphones.

The last time I even fired up my TV and stereo was last October when a friend and I watched Sahara. I do 100% of my entertainment these days via computer.

[Metricyard]

Or, better yet, just use WinDVD and watch it on your home computer with high quality sound and video cards, a good monitor, and a pair of studio-quality headphones.

The last time I even fired up my TV and stereo was last October when a friend and I watched Sahara. I do 100% of my entertainment these days via computer.

I've been doing that myself for the last few years. I just recently installed a tv card into my computer too. It works great when the comercials come on, I just jump onto the net (end up here most of the time).

As far as trying to keep your cables all nice and ordered, I believe that Murphy has a law against keeping audio/video cables neat and organized.

:lol:

[Eirik]

I'm sorry to be dense, but if I do this wrong I'll have about 20 cables running incorrectly. Besides that, I had an aggressivly unhelpful clerk at Lowes today. I wanted to see what they had on the shelf, and he basically told me that what they sold isn't what I wanted at all. When I asked what type I needed, he kept telling me to go to certain websites, and to get any quality at all, I'd need to buy stuff that was between $2 and $2,000 a foot. He wouldn't tell me what to look for, though.

What I gather here is that I can use RG6 or RG59 for basically everything (digital componant, RCA, etc). The connectors won't be a problem, I've found kits to create custom wall plates. I might try and find bundled stuff, though. Might be easier to feed through the wall.

As for using the computer, my wife and kids sometimes like to watch, too. :-)

[Roving Philosopher]

I think you'd be better off seeking advice at a store that specializes in audio/video, rather than rely on the information from the Lowe's clerk (unless the Lowe's you are referring to isn't the home improvement chain). If you've got an Ultimate Electronics store out your way, they might fit the bill.

[yuzuha]

RG6 would be that stiff stuff the cable guy uses. It has a foil shield that is impossible to solder and generally uses crimp on connectors. It is best for really long runs at higher frequencies like those going to your cable converter or from a satellite dish. RG59 generally is more flexible, lacks a foil shield and can be soldered a lot easier. It is good for lower frequency stuff like vhf television, fm radio,VCR/dvd composite/component and digital (and line level analog, though these are usually twisted pair instead of coax) audio cables

[Demigrog]

I think you'd be better off seeking advice at a store that specializes in audio/video, rather than rely on the information from the Lowe's clerk (unless the Lowe's you are referring to isn't the home improvement chain). If you've got an Ultimate Electronics store out your way, they might fit the bill.

The "specialist" stores will be happy to sell you a $15 cable for $100 and glibly claim it has better quality than the el-cheapo cable from Big Lots. I've done A/B switch tests myself on Monster cables compared to cheap Big Lots cables (but don’t go too cheap), no statistical difference for me (anecdotal evidence, of course). Of course, a "cheap" cable may be more likely to have manufacturing defects that impact signal quality, and shielding can make a difference in noisy environments or long cable runs.

To the OP, Component video uses much higher frequencies than audio, so some cable defects that are not noticeable in audio cause problems for video. It might manifest as ghosting or color imbalance, particularly if the cables for each component are not well matched. I doubt the average person would notice unless there is a severe flaw in the cable or a large length difference in the component cables.

I’m personally disappointed that there is no common optical format for digital video; seems to be a huge omission as then we could have huge run lengths with a single strand of mixed video/audio/data and not have to worry about interference. I love optical audio; the high school working at Best Buy was pretty offended when he tried to sell me a $50 6-foot optical cable and I burst out laughing. At least they've generally stopped trying to sell them as "shielded" optical cables (instead they make inane claims about the speed of light; as if a fraction of a nanosecond is going to matter in audio).

[Sammy]

You need to study the basics and decide what you really need to do. If you are talking about transmitting hi-def digital audio/video between components of your system (e.g., between a cablebox or satellite box/TIVO and a hi def TV) you should go with HDMI cables/connections. HDMI transmit both digital audio and video over the same cable, reducing the number of cables and the clutter.

Most places sell terribly overpriced cables, loaded with un-needed insulation and shielding; it is not needed because you are dealing with digital, not analog signals, and they are relative immune to interference. There are many good fora devoted to home theater/hi def where you can search and find a wealth of info. The AVS Forum is a particularly good one (http://www.avsforum.com/avs-vb/index.php?).

Many sites on the net sell good quality cables at very reasonable prices--Moonoprice.com is one I have used and sells excellent product.

RCA cables are not suitable for digital signals; component cables are bulky, do not carry audio, and are rapidlt becoming obsolescent due to the introduction of digital copyguard schemes which will block transmission over non-digital cables.

[mid]

You keep saying Digital Component. Before you spend any money, we better sort out what you mean by that.

There are a whole bunch of ways to connect a video source to an LCD TV. Worst is R/F, but I'm going to assume you're not that daft.

Next is 'Composite', which is the single RCA cable for video, and two more for audio left/right.

Then you've got S-Video, which is essentially seperates the chrominance and luminance signals from that Composite video lead and sends them to the 5-pin plug that you've probably seen the socket for a million times.

Us Europeans then get to worry about SCART cables, which are the work of The Devil, or a European TV Standards Committee, which is pretty much the same thing. 21 pins that carry both the above in both directions, seperate Red Green and Blue (RGB) signals too, power, ground, stereo audio, aspect ratio info and God only knows what else. Being American is a lucky thing here, as you'll probably never see one.

Right, then on to Component. Three video RCAs and stereo audio for a total of five RCA wires, and rated for every signal up to HD 1080i. Lovely stuff, if you're using analogue signals.

Then, most LCDs will take the 15-pin VGA signal from your PC. Which is nice, but obviously a lot of wiring and soldering when that's 15 pins before audio.

Finally, you've got your properly digital options. Two of them, in fact - DVI and HDMI. The video component of HDMI is identical to DVI, just a different plug shape. The difference is that HDMI also carries digital audio signals, so you've got everything you need in one cable (with obviously a bunch of wires in it).

If you're in a position to do so, run the HDMI - it's the most future-proof; the only thing to watch is that you'll want fairly good cables to ensure they'll cope with the bandwidth for HDMI 1.3, which is pretty busy.

If you have to run analogue, run for component. Which is what everyone else has been advising about already; choose decent wires, but don't get carried away with the silly high-end stuff.

[mugaliens]

I think you'd be better off seeking advice at a store that specializes in audio/video, rather than rely on the information from the Lowe's clerk (unless the Lowe's you are referring to isn't the home improvement chain). If you've got an Ultimate Electronics store out your way, they might fit the bill.

Bingo, although don't buy into the Monster Cable pitch, as their cables are no better, performance wise, than a set costing half as much at Best Buy or even Wal-Mart, for that matter.

[mugaliens]

By the way, I would strongly recommend you buying your cables instead of making them, as manufactured cables are precisely the same length and impedance, which reduces discoloration and timing artifacts.

[mugaliens]

Third comment: Both the media and marketers continuously and wrongly use the term "digital" when referring to audio/visual components and cabling.

Key example: http://www.twice.com/article/CA443674.html

And there the media wrongly buys into the "high end" cable myth.

Numerous tests have been done to compare Monster's cables with others such as those offered by Belkin and more generic brands found at Best Buy and Walmart.

Slight electronic differences were found.

However, in double-blind tests, subjects were absolutely unable to distinguish between them.

By the way, there is even more ridiculous fluff from eCoustics: http://forum.ecoustics.com/bbs/messages/34579/125179.html

This article is just plain ridiculous marketing designed to pump the prices of digital cables. The plain truth is that it doesn't matter how bad the waveform degrades over a digital cable, so long as 10100 is sent and 10100 is received.

By the way, digital cable such as SPDIF uses transition, so when the signal goes from positive to negative, that's a 0, and from negative to positive, that's a 1. Thus, it doesn't matter how horribly the waveform is changed due to a shoddy cable, so long as it remains positive when it's supposed to be positive, and negative when it's supposed to be negative.

I have an SPDIF out from my sound card into my computer speakers (Creative Labs 5.1 system). I just yanked the high-quality (yeah, I was a sucker, too) $14 SPDIF cable out and manually inserted 18 guage speaker wire in there, wrapping the lead around the outside of the RCA post.

This is NOT designed to work this way.

At all.

It worked fine, and I could hear absolutely no difference, as the digital stream was transmitted perfectly by this "low technology" cabling subject to massive interference.

There's additional information in the signal to provide for error detection and correction (rarely needed), improve timing for brief dropouts, etc.

HOWEVER, Component Video, the RGB used by higher end DVD players and HDTV, is ANALOG, not digital. As such, it is subject to degredation. Yes, you can use cheap Radio Shack a/v cables (and I did so for a time) instead of the more expensive cables.

And yes, in an a/b comparison test, I noticed a very slight difference in the clarity of the signal during a scene of a DVD movie between radio shack's yellow $9 solution of three very thin yellow video cables and the more expensive ($29) set of cables I purchased at Best Buy.

Repeat - it was very slight.

Still, how much did you spend on your TV? Add 10% for the absolute maximum price you should spend on the video cables.

And yes, do add both SPDIF (optical) and another digital video cabling in your walls for upgrades.

Finally, as a further aside...

I had the joy of wiring my new house in 1999. I installed 9 RJ-45 jacks throughout, as 802.11b wasn't yet off the blocks, and I wanted to be able to jack my laptop into high-speed access anywhere in the house.

I also ran the speaker wires for a 6.1 system (that being all there was at the time). As the TV sat atop a 30-year-old hi-fi cabinet containing all my components, I didn't have to run any additional cabling.

Result: Utterly Outstanding.

However, it doesn't come close to the "Big Theater" experience I have with my computer, WinDVD, a pair of $50 headphones, my 21 inch monitor, and my Creative Lab's Soundblaster audio card and my nVidea video card.

Total price for the computer solution, not counting the computer, audio, and video cards (which most people have anyway): $130.

Of course it can only be enjoyed by one person.

Total cost of my home theater setup: More than $3,000.

Something to consider...

Did I mention this link: http://www.wiredhome-weblog.com/50226711/video_cable_primer_from_ecousticscom.php

A quote:

"The job of the cable in a digital signal circuit is clear enough: maintain the specified impedance, as tightly as possible."

Horsehocky. All that need happen is to maintain the barest possible level/waveform before transition. So long as that's preserved, it doesn't matter how badly the signal degrades. Consider the fact that Gigabit Ethernet (1 Billion bits per second) travel over CAT-5 cabling, and over just 4 pairs, at that.

That's 250 million bits per second per unshielded twisted pair.

Consider the fact that digital video requires just over 3.6 million bits per second, and you see why I get a little ticked about marketers, as the a/v cables are shielded, while CAT-5 is not.

True, if you combine all three components that comes to 10 million bits per second, but that's still 25 times less data than what travels over CAT-5, an inferior technology.

So, no, you DON'T need Monster Cable "technology." I would recommend a decent quality, but don't "roll your own" and don't pay more than $100 for extended component video runs.

[yuzuha]

The thing with impedance missmatches is that they cause reflections and signal loss. The thing is that these are not really significant unless the missmatched length is a significant fraction of the wavelength of the signal.

The velocity factor of coax is about .7 so the speed of light in coax is about 2.1 x 10 to the 8th meters per second so a 10 MHz signal would have a wavelength of about 21 meters making a quarter wave a bit over 5 meters. I'd have to dig out my electronics handbook but if I remember correctly, the strength of the reflection depends on the impedence ratio and the length of the missmatched section of the transmission line. In any case, it is pretty much totally irrelevant for small missmatches between a 75 ohm cable and an inch long 35 ohm RCA plug since its electrical length is too short to be noticed (These things would be important to a cable tv company with miles of coax and possibly long sections of missmatched cable, but no you don't have to worry about special impedance matched rca plugs or short video patch cords).

For that matter, I've used 6 foot 52 ohm RG8 cables with RF2RCA adaptors on the ends for video cables (needed a video cable but all I had was 50 ohm shortwave radio cables) and noticed no change at all in the picture when I finally got around to buying some 75 ohm coax to make proper video cables out of.