Optical cable

Discussion in 'Digital Sources' started by wanders, Jun 25, 2017.

  1. wanders

    wanders Super Member

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    I recently added a Bluesound Node 2 to my system. I'm going to run the output through my Marantz sa7004 dac. I'm going to need a fairly long optical cable: 20' - 25'.

    I believe in using good quality interconnects, but know zero about optical cable. So any advices would be welcome. What are the variables to consider? How sensitive is sound quality to cable characteristics? Etc.

    Thanks
     
  2. Splatter Pak

    Splatter Pak High-End Scrounger

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    Be sure to get a good quality glass-fiber cable, and avoid plastic Toslink. Simple.
     
  3. charles 1973

    charles 1973 Super Member

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    4thChoice, transmaster and faber12 like this.
  4. Bodyblue

    Bodyblue AK Subscriber Subscriber

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    Optical cables
    Most of what you'll be transmitting over optical cables is digital, namely audio in PCM (Pulse Code Modulation) or Dolby Digital format. All Dolby Digital decoders are designed to cut out completely if they don't get a perfect signal. If bits are missing or wrong, the decoder transmits silence before it risks sending something that might damage your speakers. So if you're getting a Dolby Digital signal, and it's not cutting out, your optical cable is fine.

    If you're transmitting PCM, the audiophile answer is that different optical cables can cause different amounts of jitter. The reality is, the digital-to-analog converter in your gear has vastly more effect on the sound. Could a "better" optical cable result in audibly better PCM sound? Doubtful.

    https://www.cnet.com/news/when-are-expensive-cables-worth-it/
     
  5. transmaster

    transmaster Addicted Member

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    Last edited: Jun 29, 2017
  6. Electone

    Electone Well-Known Member

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    Monoprice.
     
  7. ferninando

    ferninando AK Subscriber Subscriber

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    I prefer digital coax but thats just me.
    no double conversion .
     
  8. transmaster

    transmaster Addicted Member

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    Me too because as Blue Jeans Cables says you can use them as a conventional analog cable.
     
  9. restorer-john

    restorer-john Super Member

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    I prefer optical. There is no 'double conversion' in optical. The signal turns on and off an LED and at the other end, a photo transistor turns on an off. The most it runs through is a mark/space 50/50 duty cycle gating before entering the PLL.

    Coaxial properly done has a transformer optimized for 75ohm and at the other end a bunch of components to clean up the signal (filter/schmidt triggers etc) before running into the same front end. Optical is simpler and completely resistant to ground loop currents or electrical interference.

    Optical offers advantages that coaxial can only dream of, but we've got both to play with so have fun I say. :)
     
  10. transmaster

    transmaster Addicted Member

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    From the point of view of a ham radio operator an optical cable does not have problems with RFI in a room with high powered transmitters. On the other hand this is the difference between a quality coaxial cable and a cheap one. But it is getting very difficult to find a really poor quality coaxial digital cable.
     
  11. techguy0192

    techguy0192 AK Subscriber Subscriber

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    I prefer optical cables. Due to the nature of optical cable, there's zero risk EMI interference....whether is 1' or 20' in length.

    I've never be into comparing coax and optical because it's digital...ones and zeros....they get there or they don't.
     
    Bodyblue likes this.
  12. for_p1

    for_p1 Addicted Member

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    Actually jitter is a real thing (though one can argue if it can be heard). If you look at spectum of signal with significant jitter - you will see high amount of high frequency distortion products. That is why any good DAC should have ASRC or other advanced clock recovery circuit.
     
  13. for_p1

    for_p1 Addicted Member

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    And then you increase a chance of creating a ground loop and associated noise/hum.
     
  14. wanders

    wanders Super Member

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    Appreciate all the input. I ran the Node 2 with a 12' optical cable for a period then moved the unit a little farther away and needed a longer cable. Based on Blue Jeans' comments, I purchased a 30' Belden 1694A coax cable from them. Their most persuasive arguments were that optical cable was more fragile than coax and the Belden 1694A showed no loss of signal or sound quality up to lengths of 50'. Having listened to the 12" optical and 30' coax, I could not detect a difference. Time will tell.
     
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  15. transmaster

    transmaster Addicted Member

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    You can't go wrong with BJC. Their advice is straightforward and it does not have any voodoo science. Belden cable is a industry standard and has been since it's founding by Joseph Belden in 1902. Read up on the history of Belden it is fascinating. I stopped using optical cables several years ago. The optical jacks on my Onkyo are fragile the locking mechanism a joke. I only used a couple one from my ASUS Zonar Essence sound card and the other from the Apple TV 3. When I built a new PC the Zonar sound card was retired in favor of the much, much better AMD True Audio coming out of the Radeon GPU via HDMI. I also configured the Apple TV for HDMI sound output. I have a BJC coaxial digital cable for the digital LFE cable to my subwoofer.
     
  16. bacobits

    bacobits Active Member

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    Just picked up a Lifatec optical cable. It is very good.
    They are used in the medical field.
     
  17. transmaster

    transmaster Addicted Member

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    Nice quality wish I would have known about these cables when I was still using the ASUS Zonar Essence sound card. As I said above what caused me to abandon optical cables was the poor quality of the optical jacks on my Onkyo TX-NR709. The locking doors on the ports fall apart I had to tack the plug in place with a drop of hot glue. With the PC I assembled a couple of years ago I retired the Zonar, and used the Radeon GPU audio and with the Apple TV-4 I went to it's HDMI audio feed.
     

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