I am thinking of upgrading my 45' coax digital cable...

Discussion in 'Archived Threads 2001-2004' started by John Morris, Jan 13, 2002.

  1. John Morris

    John Morris Guest

    I am currently using a quad shielded, copper core, RG-6 cable with F connector to RCA adapters on each end. I seems to work just fine. I am wondering about upgrading that cable but wonder if I am going to hear a difference. I've looked at Bettercables but a cable from them will cost me over $200. This cable is used to send DD and DTS soundtrack signals from my DVD and HD STB units.

    Any suggestions... or just stay pat?
     
  2. Mark Rich

    Mark Rich Second Unit

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    How long is this cable?

    Think the weekest part of your cable is the F to RCA adapter.RG6QS is also not the best cable to use. Fine for antenna applications but not for auydio/video applications. Yes it will work but not as well as a premium RG6 cable.

    For audio you will notice an improvemnt with a better cable. Ideally you should get a high performance digital coax cable such as the Rhinocables, Boldercables, Diycable offerings but the cost will be high.

    You could save money by going with a good Canare or Belden RG6 cable with the correct termination. You will notice an improvemnet in sound but not as much as with one of the above sepcialty cables.

    Try e-mailing the following and get a quote for a single run of Canare or Belden RG6 with Canare connectors. Heck if it doesnt improve the sound (which I doubt) you could always return it.

    Rhinocables.com

    Cscables.com

    KustomKables.com
     
  3. John Morris

    John Morris Guest

    Mark: It is 45 feet long. Since this is only passing a digital signal, how will the sound improve versus my current copper RG6QS setup? Keep in mind that this cable is only used for movie and TV coax digital audio signals sent to my pre/pro for DD, DPL and DTS decoding.
     
  4. Mark Rich

    Mark Rich Second Unit

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    What kind of cable are you using? Is it bare copper or tinned, are the shields copper, tinned copper or aluminum etc.. Is the dielectric foamed or solid? All these properties have an effect on both audio and video.The longer the run the more critical the quality of the cable.

    Just by eliminating the adapters you should get a small improvment in sound.

    With a premium cable You should notice clearer highs, tighter bass and possibly detail that you never noticed before. I have never used a cable that long but noticed great improvemnt with cable as short as 1m when I went from Monster digital to Belden 1506a based cable (Rhinocables).

    I cant recall where your cable is being run from. AVR to power amps or source to AVR etc.. If from source then I'd say that is far to long a run for optimal performance. Would recomend you check out the audio asylum forum as there is currently a discussion on max allowable IC length.
     
  5. Kevin Coleman

    Kevin Coleman Second Unit

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    Mark,
    He said this was his digital coax from DVD player to receiver.
    I am also curious how would a specialty digital cable from the places you mentioned be any better than a DIY made one from Belden or Canare? This is Digital Audio? A coat hanger would probably work?
    John,
    If you had the tools you could build a high quality Digital Audio cable 45' long with Canare cable and Canare crimp on ends for 18 dollars. If you don't want to buy the tools and DIY then I am sure you could find somebody here on the forum that could build one for you for a small fee. I wouldn't pay over 40 dollars for one though that is for sure. I definitely wouldn't pay 200 dollars.
    Kevin C. [​IMG]
     
  6. John Morris

    John Morris Guest

    Guys: Thanks for all your suggestions and opinions! This cable will carry a DD, DPL or DTS signal from either my DVD player or my HDTV Tuner(STB) via an Audio Authority 1177 Digital Switcher. Since these signals are packeted signals, I have not experienced any jitter and they sound just fine for this application in spite of the length of run and my usage of common RG6. However, I am in the process of finalizing my system, for the next year or so, and just want to cover all my bases. I have already replaced my component video cables with BC SS and my audio cables with Outlaw PCAs, and I just thought that I should get a "real" digital coax cable for my long run and forget it...? Still, generally, I side with Kevin and his opinion on digital coax cable.

    Mark: did you notice the cable caused differences you mentioned in your previous post when listening to non-pcm, packeted digital audio like DD and DTS?
     
  7. Mark Rich

    Mark Rich Second Unit

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    Kevin,

    Sorry, missed that.Did not have my glasses on I guess.

    If you belive a coat hanger would work then go ahead and use one. If you believe that digital is digital and the cable makes no difference then I'm not going to start a cable debate with you on the subject. Dont suppose you use lamp cord for speaker cable do you? Similar reasoning in my opinion.

    The reason the cables I mentioned are better in this role is because of the properties of the coax cable used. They use Teflon as insulation with a solid bare copper core.The Belden cables also have better shielding than the Canare cables. The mentioned cable makers also use an additonal shield to eliminate further RFI/EMI.

    Yes, you could go out and buy the material and make one yourself. The Cable asylum is full of advise on how to do this.

    Read and compare the specs on both the Belden and Canare web sites. They do not have the the same specs and Canare does not make Teflon based cables. Therefore they do not sound as good. Yes they work well but they do not offer the final bit of detail that the above cables do. I know because I have actually compared them (Monster, Canare, Belden and a few other retail brands)and in my system there is a definate improvemnt.

    I would not recomend John go out and buy a specialty 45ft digital coax from Rhino,Bolder or Diy. The cost would be prohibitive and I think the performance increase with such a long run would be wasted. To get the best from a system such as this I would move the component closer to the AVR. Even if I had to re-arrange the whole room in order to do this.

    The S/PDIF format is only rated up to 50ft (if I recall correctly). Many sources do not have good enough output stages to handle a run that long. So the use of a premium low capacitance cable will only help the situation.

    If I was john I would at the very least purchase a good Canare 18AWG cable from an on-line source or better still a belden 1694a/1695a based cable. At least he will get a performance increase without breaking the bank. The cost should be between $50 and $75.

    John,

    Yes the audio improvemnt was there with all audio material.
     
  8. John Morris

    John Morris Guest

     
  9. Bob McElfresh

    Bob McElfresh Producer

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    John: I agree. If you have a choice between needing a long digital cable or long video cables, go with the long digital cable.
     
  10. Bob McElfresh

    Bob McElfresh Producer

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    John: Call MarkerTek at 800-522-2025 and ask about a Canare digital cable SPDIF with the Canare plugs on the end.

    They have one for 50 feet listed for $77 but with BNC connectors (MarketTek sells to broadcasters who prefer the locking BNC connectors).

    Another page lists S/PDIF Digital Cables (which is what you want) for 15 ft $27 using Canare coax & plugs:

    S/PDIF10 - $24

    S/PDIF15 - $27

    Seems to be $3 for 5 feet so you could gestimate the extra 35 feet on top of the 15 foot price would be:

    S/PDIF50 - $27 + 35ft ($3/5ft) = $48

    Or if you wanted to try the Belden cables mentioned above, talk to them. They do custom work.
     
  11. Kevin Coleman

    Kevin Coleman Second Unit

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    John,
    If you look here I can make you a cable just like this one except it will be 45' long for 35.00 dollars plus shipping.
    That is Canare L-5CFB RG6 coaxial cable terminated with Canare true 75 OHM RCA connectors. I could ship it tomorrow if you like.
    http://home.kscable.com/kevshometheater/new_page_1.htm
    Kevin C. [​IMG]
     
  12. Wayne A. Pflughaupt

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    Mark,

    With all due respect, I think you are making the classic “cable guy” mistakes, for one assuming that if a cable made an audible difference in your system that it will in everyone’s, and not even finding out if John’s equipment is good enough to even hear a difference – especially with digital cables, which are even more subtle than regular cables.

    That said, John, it never hurts to try a high-quality cable. If you can find a return-friendly vendor, go for it.

    Even with the DIY approach, Mark’s advice on using good-quality cable should be heeded. At the very least any RG-6 for audio use (both analog or digital) should use copper for both center conductor and shield.

    John, don’t you live in or around Houston? If so, I could solder some RCA connectors directly on to the RG-6 for you, provided the shield is not made of steel. That would at least eliminate the adapters.

    Regards,

    Wayne A. Pflughaupt
     
  13. Chu Gai

    Chu Gai Lead Actor

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    what testing protocol do you use Mark to establish your relative rankings of cables?
     
  14. John Morris

    John Morris Guest

     
  15. Wayne A. Pflughaupt

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    John,
    Nice system! I have a JVC HR-S7500, too, as well as a 7100 and 7300. Great machines.
    Hope you know I wasn’t dissing your system; that was directed to Mark, and assuming he didn’t know anything about your system (’course, I’ll owe him an apology if it turns out he did! [​IMG] ).
    It’s just that too many times I see someone ask about cables and the “cable guys” will tell him what an audible or visual improvement it will make, even though the inquirer never said if he had a $50,000 system or a $500 system.
    Regards,
    Wayne A. Pflughaupt
     
  16. Rich Malloy

    Rich Malloy Producer

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    If given a choice between inexpensive coax (say something like PartsExpress's Dayton brand at approx. $10/yard) vs. a low-priced optical cable, which would be superior?

    In short, do I have to pay the big bucks for coax to be an improvement over optical?
     
  17. Mark Rich

    Mark Rich Second Unit

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    Wayne,

    I am talking about a noticeable improvement on a mid-fi system and not a mega priced audio/video phile system. i assumed that he had a typical mid-fi system.

    Bob,

    I disagree. You will have less problems with a long video cable compared with a long digital cable. like I stated the S/PDIF performance is hitting its limit at around 50'. decent video cables can go hundreds ( 1000' + with some cable)of feet depending on the cable and still meet full specs.

    of course in John's case where he cant justify the cost of buying additional cables or moving his sytem then doesnt really have a choice.

    CHU,

    I'm not going to touch the double blind testing etc... debate
     
  18. Bob McElfresh

    Bob McElfresh Producer

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    Mark: If I could disagree with your disagreement..errr (you know what I mean) [​IMG]
    We routinely run digital signals hundreds of feet over cable that is much less shielded than RG6 coax. And yes, the computer network IS packatized, but this allows the hubs to track errors and frankly, errors are the exception rather than the rule.
    And my little 18" DSS dish recieves TONS more data than the SPDIF cable handles and it goes through miles and miles of air/fog/clouds, etc.
    To do the same thing in Analog takes a 9-foot dish.
    Analog coax has a length component which is why all the manufacturers that publish frequency specifications roll out 100 feet for their frequency tests so that we can do a apples-to-apples comparison. Attenuation in the signal IS a concern for analog.
    A digital signal can drop by as much as 40% (intollerable for a analog signal) and still appear to have PERFECT transmission. Attenuation of a digital signal has nearly dropped off the issues list.
    So Digital is a LOT less sensitive to the cable/transmission medium than analog. This is the basic tenate behind my recomendation of "Short analog and long digital cables".
    You may disagree with my conclusion Mark, but we all know that traditional Analog systems are all being converted to Digital. IMHO it's because of it's basic robustness, reliability and INSENSITIVITY to the transmission medium.
     
  19. Kevin Coleman

    Kevin Coleman Second Unit

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    I agree with Bob. It would be much better to run one 45' digital coax than run two 45' component video cables. Remember he said he is running a 45'long run of digital coax right now and it works fine. We are not even talking PCM here where it might make a difference in such a long run but we are talking about DD and DTS specifically. With DD or DTS if you are not getting audio dropouts then you are already getting a perfect signal.
    Kevin C. [​IMG]
     
  20. brucek

    brucek Second Unit

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    Interesting discussion - given the choice in a 15 meter distance and the interfaces involved , would I choose long digital cable or long video. I don't think the answer is as clear cut as a few seem to think...

    With the digital cable I don't feel there's too much difference between PCM, AC-3 or a DTS bitstream.

    The responsibility for clocking the AC-3 data is still that of the SPDIF transmission format. This has little to do with the AC-3 standard. The SPDIF format combines the data and clock using biphase-mark encoding. The clock is then recovered by the sampling and DAC circuitry generally using a phase locked loop. So, as it is with PCM data, the timing of the bits for DAC clocking is determined by the zero-crossing point of the signal, and any distortions can introduce jitter.

    So jitter would be the only effect the (so-called) digital cable would have on the digital data - both PCM and AC-3. This time-base error is up for debate whether it's audible or not. How much of an effect will the cable have. Well I think everyone agrees that we aren't considering bit errors. Not a chance.

    Consider that AC-3 5.1 audio is compressed data. That means if you have so much as a single bit error the decoder will have no way of uncompressing the data. The audio signal will completely drop out until the decoder re-syncs to error free data. Similarly, you'll hear some pretty bad audio dropouts when there are any bit errors in PCM data.

    Besides, at these low frequencies and cable lengths, there just ain't gonna be any bit errors. The SPDIF standard supports frequencies from 100Khz to 6 Mhz with up to 15 meter distances. Generally, digital audio will be in the order of 1Mhz. Will the cable cause any slewing of the signal at these frequencies - maybe. Can you hear the effects of jitter - maybe. Personally, I don't think so, but there's lots of anecdotal data to support it.

    Baseband video frequencies for NTSC are in the order 6Mhz. HDTV signals are several order higher. At these low frequencies and only a 15 meter distance, will there be visible degradation - maybe........

    Mmmmmm..tough question.

    My advice to John Morris - keep the cable you have - its great...

    brucek
     

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