Coaxial Cables

[Alex2507]

I prefer shielded coax over these type of designs but that's only b/c I come from an RF background and know what works and doesn't work in the worst possible environments.

Please talk to me about RG-59, RG-6 and RG-6 Quad shield as it applies to audio and video signals at various lengths of cable.

Specifically how long a run can RG-59 be used for as a:

1. Subwoofer Cable?
2. Digital Audio Cable?
3. Component Video Cable?
4. Analog Audio Interconnect?

Is RG-6 Quadshield of appreciable benefit over the thinner and more flexible RG-6?

The RG-59 that I have is Belden M 8241. Link has data sheets at top of page (you have to scroll up). It's 23 gauge copper coated steel conductor with a 95% braided copper shield. I have 2 runs of about 50' each and Home Depot sells compression connectors that I can use with my compression tool. Anyway I really like the stuff and I'd like to know it's limitations. If I can use it for most of my needs I'd like to know so that I can start lusting after a 500ft roll and a crate of connectors.

TIA ... Gene.

 

[bandphan]

Your fine for 50'. I've run 100+ feet for component hd. The only applications for Quad would be commercial installations of video, I've found very little use for it. Regular 6 for home distribution and 59 for interconnects.

Edit: I'm sure AJ and Jerry might have a different take though


Also 50pk connectors from monoprice is about 20 bucks and 100pk of colored selves/rings cost about $8. Your wire management is gonna love you

 

[Rickster71]

If I may add my two cents.
Aside from the bandwidth issues and different shielding. (which don't matter in our sub or RCA wiring)
RG6, has a larger center conductor: 18 AWG
If you can get your wire cheap or free, that's good, and if it has the steel core, so be it. Though if you have the choice, look for the solid copper core; it's more flexible, and doesn't distort the inner foam insulation when bent.
And the babes dig the thicker RG6 Quad, I'm just sayin.

 

[highfigh]

If I may add my two cents.
Aside from the bandwidth issues and different shielding. (which don't matter in our sub or RCA wiring)
RG6, has a larger center conductor: 18 AWG
If you can get your wire cheap or free, that's good, and if it has the steel core, so be it. Though if you have the choice, look for the solid copper core; it's more flexible, and doesn't distort the inner foam insulation when bent.
And the babes dig the thicker RG6 Quad, I'm just sayin.

It's all about size with you, isn't it?

Another reason to get the solid copper core is that most cable cutters (the really sharp ones, not diagonal cutters) will have major problems with steel core cable. They get dinged up every time steel core cable is cut.

 

[Alex2507]

So a couple of HD channels were pixellating (SP). Verizon came out and swapped out the box. It still pixellated. They came out again. These guys are all management because Verizon is on strike. The 2nd guy to come out was Asian with a Phd in physics and he explained that switching from RG-6 Quadshied to anything else was a bad idea because the different wire caused a reflection in the signal at the interface which caused an unstable distortion. He first blamed the pixellation on what he called an overly tight connection on my home terminated RG-6. I explained that he could only quantify the tightness as being more than he could undo with his fingers. I have a Phd in pliers. Well he changed my cable out and the pixellation went away and I ate crow ... until it pixellated again. We found a Verizon service box with about a dozen really loose connections.

Even though my I don't believe my use of overly tight straight RG-6 was the problem I still kept the Quad after finally having part of this question answered. The explanation was that the cable acts as a wave guide and if there are different cables on either side of a connection it caused a phase dependent refection/distortion that would degrade the signal. He also said that other coax cable connections to other devices also contributed to the distortion in each others signals because it is a network.

The guy lost me here and there but he was good about going back and explaining and that's what I got out of it.

 

[highfigh]

So a couple of HD channels were pixellating (SP). Verizon came out and swapped out the box. It still pixellated. They came out again. These guys are all management because Verizon is on strike. The 2nd guy to come out was Asian with a Phd in physics and he explained that switching from RG-6 Quadshied to anything else was a bad idea because the different wire caused a reflection in the signal at the interface which caused an unstable distortion. He first blamed the pixellation on what he called an overly tight connection on my home terminated RG-6. I explained that he could only quantify the tightness as being more than he could undo with his fingers. I have a Phd in pliers. Well he changed my cable out and the pixellation went away and I ate crow ... until it pixellated again. We found a Verizon service box with about a dozen really loose connections.

Even though my I don't believe my use of overly tight straight RG-6 was the problem I still kept the Quad after finally having part of this question answered. The explanation was that the cable acts as a wave guide and if there are different cables on either side of a connection it caused a phase dependent refection/distortion that would degrade the signal. He also said that other coax cable connections to other devices also contributed to the distortion in each others signals because it is a network.

The guy lost me here and there but he was good about going back and explaining and that's what I got out of it.

Did he leave any taps without termination caps? That causes reflections, too.

Crimped F connectors aren't used anymore in communications- if you don't have a compression tool, you need to get one. If the shield is compressed into the dielectric, problems arise. Neighboring houses with un-terminated cables can cause problems outside, unless they have a block where it enters (like they use for MoCA network devices).

 

[Alex2507]

Did he leave any taps without termination caps? That causes reflections, too.

Crimped F connectors aren't used anymore in communications- if you don't have a compression tool, you need to get one. If the shield is compressed into the dielectric, problems arise. Neighboring houses with un-terminated cables can cause problems outside, unless they have a block where it enters (like they use for MoCA network devices).

I already would have taken care of capping taps.I knew about that. Thanks for the vocabulary lesson thus far. I still have to look up MoCA but that sounds very familiar. We both had compression connectors so that's equal equal. Our problem went away for good after tightening the connectors outside.

 

[MR.MAGOO]

So coax cable can only do video/TV and CAT 5e or higher can do it all?

 

[Speedskater]

The RG-6 Quad-shied that the cable TV company's use is optimized for TV channel high frequencies up to 1 or 2 GHz. So it's bad for analog audio and only fair for digital audio and video signals.
There are many other coax cables optimized for these purposes.
Cat 5E can do video but not TV channels.

 

[highfigh]

I already would have taken care of capping taps.I knew about that. Thanks for the vocabulary lesson thus far. I still have to look up MoCA but that sounds very familiar. We both had compression connectors so that's equal equal. Our problem went away for good after tightening the connectors outside.

MoCA (Multimedia over Coax Alliance) uses the network over coax pieces that cable companies use (or, consumers who don't want to pay the cable companies for their parts)- Wi3 is one company and I think Belkin, Netgear and others sell these. If the block isn't used at the head end in the building, it passes to any nearby cable customers and it's less of an interference issue, but it can do that. The other problem is that an unblocked network could be used for access of the services that are being paid for by someone else and we couldn't have that, could we?

 

[highfigh]

The RG-6 Quad-shied that the cable TV company's use is optimized for TV channel high frequencies up to 1 or 2 GHz. So it's bad for analog audio and only fair for digital audio and video signals.
There are many other coax cables optimized for these purposes.
Cat 5E can do video but not TV channels.

Quad is used for all kinds of alternate signals- why would it not work for analog, digital and video? Coax (RG6 AND Quad) is usually sweep tested to at least 3GHz. Over long distances, it can be a problem but 100' is longer than most audio and S/PDIF runs. I don't like it for terminating in racks or other closed spaces because it's usually too stiff.

 

[Speedskater]

Quad is used for all kinds of alternate signals- why would it not work for analog, digital and video? Coax (RG6 AND Quad) is usually sweep tested to at least 3GHz. Over long distances, it can be a problem but 100' is longer than most audio and S/PDIF runs. I don't like it for terminating in racks or other closed spaces because it's usually too stiff.

Because it's optimized to work at 1 to 3 GHz means the trade-offs mean that it doesn't do a good job at low frequencies. Low frequencies require a heavy braided shield.
True a cable TV company quad-shield will work at low frequencies but the back-ground noise may be 20 dB more than a well chosen coax.

 

[Alex2507]

Because it's optimized to work at 1 to 3 GHz means the trade-offs mean that it doesn't do a good job at low frequencies. Low frequencies require a heavy braided shield.
True a cable TV company quad-shield will work at low frequencies but the back-ground noise may be 20 dB more than a well chosen coax.

I ran 20 or 30 feet of quad for my subs. You think you could hear a difference going to rg6 95% copper braid? 20 decibels sounds like you should be able to hear it.

 

[highfigh]

Because it's optimized to work at 1 to 3 GHz means the trade-offs mean that it doesn't do a good job at low frequencies. Low frequencies require a heavy braided shield.
True a cable TV company quad-shield will work at low frequencies but the back-ground noise may be 20 dB more than a well chosen coax.

'Optimized' means different things to different people. Until fairly recently, many satellite and cable installers weren't required to use RG6, so they didn't. I still see RG59 on satellite and cable installations that are fairly new. Unbelievable!

Do you have any idea how many subwoofers have RG6/RG6Q from the AVR or pre-pro? More than not, is my guess.

 

[KenM10759]

I have about 1/3rd to 1/2 of a 1000ft roll of that same Belden 8241 RG-59U that I'm willing to part with if anyone wants it. Insult me with an offer. I think it could ship in a box that qualifies for US Postal Service Large Flat Rate box, so about $20 to ship.

 

[c.coyle]

The RG-6 Quad-shied that the cable TV company's use is optimized for TV channel high frequencies up to 1 or 2 GHz.

Optimized for what qualities or characteristic(s)?

So it's bad for analog audio and only fair for digital audio and video signals.

What exactly is bad about it for analog audio? For digital audio? For digital video?

There are many other coax cables optimized for these purposes.

What qualities or characteristics are optimum for analog audio? Digital audio?

 

[Speedskater]

Steve Lampen of Belden Cables has written to entire books on the subject of cables.

"Wire, Cable, and Fiber Optics for Video & Audio Engineers"

"Audio/Video Cable Installer's Pocket Guide"

Stephen H. Lampen

They have chapters on cable properties.

 

[Speedskater]

The Steve Lampen, Belden Blog.
I don't know how many of the 100 blogs are a cable properties.

http://www.belden.com/blog/index.cfm?authorID=1000035&postedby=Steve Lampen

 

[Speedskater]

Some good digital cables:

Coaxial Digital Audio Cable: Belden 1694A
Our favorite cable for coaxial digital audio use is Belden 1694A "Brilliance" precision digital video coaxial cable, a 75 ohm coax engineered for low signal loss over long runs. These cables are exceptionally well shielded to keep outside electromagnetic interference from entering and polluting the signal; the shielding consists of a combination of a dense (95% coverage) tinned copper braid and a double-sided aluminum-on-polyester foil, for the best protection both against EMI and RFI.

Belden 1505F Coax:
For most applications, where cables will be installed once or a few times and seldom handled, we recommend the solid-conductor coaxes above. However, if you will be handling your cables on a regular basis because of frequent system reconfigurations, or mobile use, or what-have-you, a multistranded, more flexible cable will stand up to that handling much better, and of course it's a bit easier to route. Until recently, there was no 75 ohm high-flex cable available that could compete with Belden's best cables for impedance consistency and bandwidth--to fill this void, Belden introduced 1505F, a highly flexible cable designed for use in video patch panels. Belden 1505F uses a compacted stranded center conductor and a double braid shield, and is sweep-tested to 3 GHz. The result is a more flexible, more durable cable, at a very slight sacrifice in performance characteristics.

Belden 1695A Coax:
Belden 1695A is a Teflon-dielectric version of 1694A and carries a plenum fire-safety rating; its performance is essentially identical to that of 1694A.

more info at:
http://www.bluejeanscable.com/store/digital-audio/index.htm