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Discussion Starter · #1 ·
Hey guys, I did a search and lots of threads regarding cable length came up but none in regards to toslink and spdif that I could find.


What I am trying to accomplish requires me to run a digital audio cable approximately 50'. From the little bit of investigating I have done through google searches I found out that optical/toslink isn't the best choice, that leaves me with digital coax.


Does anyone have experience with running digital coax 50'+?

Will I run into any signal loss/drop?

I read that rather than buying a digital coax cable that I should use a rg-6 quad shielded cable and terminate the ends with the proper digi.coax/rca connectors or buy the adapters. Good or bad idea?


My reason for such a long run is to get a cable from my theatre pc to my 2 channel room. I'd rather not buy an intermediate device to put in the 2 channel room (ps3, squeezebox). I know what i'm doing isn't the best method, but i'm trying to keep things simple and not degrade sound quality (much). Supposedly the rg6 quad shield is great for longer distance digital transmission without any drop/loss. Hoping somebody who has done this or knows more about this can give me some input.


Please don't shoot me but the cable will probably be purchased from monoprice for it's cost effectiveness, unless somebody else can recommend a place to buy a cable for a reasonable price. I know a better branded cable of the length would cost me an arm and two legs.
 

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Fifty feet is no problem, but don't use Quad-Shield! It's not designed for this application. Regular RG-6 is much more appropriate.
 

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Quote:
Originally Posted by Speedskater /forum/post/18306998


Fifty feet is no problem, but don't use Quad-Shield! It's not designed for this application. Regular RG-6 is much more appropriate.

A few years back I did almost 50' with standard RG-6 and for over 2 years never had a dropout. The only caveat is it's a little hard to work (bend) with.
 

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Quote:
Originally Posted by Speedskater /forum/post/18306998


Fifty feet is no problem, but don't use Quad-Shield! It's not designed for this application. Regular RG-6 is much more appropriate.

I agree with using RG-6. Why couldn't the OP use RG-6 Quad Shielded cable?


I was under the impression RG-6/UQ was a step up from RG-6/U which is dual shielded. I was thinking quad shielded is overkill for this application but it could be used so the OP has even better shielding from interference. Maybe I am misinformed about quad shielded RG6 vs regular RG6. Part of the reason I ask about the differences is I am going to replace some older RG59 cable running to rooms in the house. I was thinking of going with RG6 Quad Shielded.
Quote:
Originally Posted by robbbby /forum/post/18306958


Please don't shoot me but the cable will probably be purchased from monoprice for it's cost effectiveness, unless somebody else can recommend a place to buy a cable for a reasonable price. I know a better branded cable of the length would cost me an arm and two legs.

I'm a fan of Monoprice. Due to their problems recently complete the purchase using Google Checkout so your credit card info isn't shared with Monoprice. You may want to check out http://www.bluejeanscable.com and http://www.parts-express.com . Monoprice will probably beat them on prices but the other two have some really good products at decent prices.
 

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Discussion Starter · #5 ·
Thanks for the replies and advice on other cable/wire stores.


It probably won't make a difference for me between the regular rg6 and the quad shielded, although i'd like to know the reason why the quad shielded isn't good for this sort of thing. I always assumed the shielding just helped with interference, especially if run in the walls near 120/240v wiring.


Thanks.
 

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Quote:
Originally Posted by Speedskater /forum/post/18306998


Fifty feet is no problem, but don't use Quad-Shield! It's not designed for this application. Regular RG-6 is much more appropriate.

It really depends on what you are calling Regular RG-6. RG-6 cable can most certainly go beyond the fifty foot range for SPDIF (digital coaxial audio) but some RG6 is rated at 1 gig for cable tv use, 2 gig up for satellite use, but for digital audio you have to have something that works with those frequencies like Belden 1694A. It has a solid copper center conductor as opposed to copper covered steel used is most cable applications. It is also dual shielded (quad is not necessary). This cable can also be used for component video cable and is sweep tested at 4.3 gig as I recall.

I would not be afraid to run this cable at lengths above 100 feet for spdif applications.
 

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Quote:
I always assumed the shielding just helped with interference, especially if run in the walls near 120/240v wiring.

This is a common misconception. Sheilding does nothing for electromagnetic interference. A coax cable is a transmission line, the shield is part of the circuit and the construction of the line ensures that the impedance between center conductor and ground (the shield) is maintained along the length of the cable.
 

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Different RG-6's are designed (optimized) for different signal frequency ranges.

Quad-shield is designed for extremely high frequencies, beyond 1 gig.

So they trade-off lower frequency shielding for that 1 gig.

Digital audio is at a rather low frequency when compared to 1 gig.
 

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The cable I suggested works fine because it has a solid copper center conductor. Some RG-6 uses copper covered steel and as Kevin explained is made for higher frequencies. The 1694A covers quite a range and is great for many analog and digital applications.
 

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Quote:
I read that rather than buying a digital coax cable that I should use a rg-6 quad shielded cable and terminate the ends with the proper digi.coax/rca connectors or buy the adapters. Good or bad idea?

No, bad idea. I'm assuming you mean standard RG6 as commonly used for cable TV/SAT, which is copped-clad steel. For this application, you want to be using a solid-copper coax cable. 50' is not super-duper far for SPDIF, a good solid copper RG59 or RG6 video coax should be way plenty adequate. You would probably be okay with mini coax as well.


There is also some very cheap toslink cables from monoprice at longer lengths, I'm using I think like a 30-40ft toslink cable from my Mac to my receiver for audio no problem.


Here's a 50ft coax for under $10:
http://www.monoprice.com/products/pr...seq=1&format=2


Here's a 50ft toslink for under $10:
http://www.monoprice.com/products/pr...seq=1&format=2



Either way, no need to spend a lot of money.


If you want the absolute best coax you can get, then 1694a, still very affordable, but that'll run you about $50 I think at bluejeans.com.
 

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There is quite a bit of 1694a on Ebay for very low prices. If you are able to solder you could save a considerable amount. I have had experience with it but not so much with the imported cables. The copper covered steel center conductor is not suitable for this application because of the skin effect. Alternating current at high frequencies travels over the outside of a conductor and does to a greater effect as the frequency goes up as I recall.
 

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I run the previously linked $10, 50 ft monoprice coax cable from my computer to my denon 2807 with no problems. Nothing fancy done whatsoever, just hooked it up, strung it through the ceiling (drop tile) from one end of the basement to the other room with the computer. Never had an issue.
 
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