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Optical and Coax cable length?

Is 1M (3.3Feet) of Coax or Toslink digital cable the right length?

  • No! Too long! 0.5M (1.6ft) is good enough!

    Votes: 2 13.3%
  • Yes, perfection!

    Votes: 6 40.0%
  • No! Too short! 1.5M (4.9ft) is much better!

    Votes: 3 20.0%
  • No! Too short! 2.0M (6.6ft) is much better!

    Votes: 0 0.0%
  • No! Too short! 3.0M (9.9ft) is much better!

    Votes: 0 0.0%
  • No! And you don't have the proper length in the poll! (please state length below)

    Votes: 4 26.7%

  • Total voters
    15
Status
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I have a 1 m optical cable that is just too short (the cable only just makes it but with the strain the connectors are pulled slightly - intermittent loss of connection), and I can't move the components closer together. Here a 1.5 m length would be great, but I just have never got around to it. Using a coax currently. But for the fibre link, length should not be an issue, unless there is an interaction with the nominal wavelength of 650 nm & the maximum output power of the laser diodes. I have never looked at the standard re the TOSLink interfaces. Will be interesting to know what the limitations and recommended minimum and maximum lengths are.

Kevin
 
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@davidsrsb - exactly. And reflections can occur at the coupling points. Though error correction should cater for that.
P.S. After looking at a brief synopsis of the standard, I see they say that the standard commercial product is a high quality plastic "pipe"; WT*! proper silica/glass is not expensive, and is a much better medium. The plastic material has an extremely high attenuation rate compared to plastic.
 
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Each cable has an official spec which you can look up.
TOSLINK I think standard maximum is 5 meters, but that is because of cheap plastic fiber.
Glass can run a long way. Miles with the right GBIC. Don't know if anyone is making SPDIF in glass for long haul. I would bet 50M to be easy.
Don't know the coax length. Just 75 Ohm so I see little reason for it not to be good for 50 meters or so unless the driver is crap.

As you would expect, the longer the cable, the more important for a quality cable. Not some magic "audio crap", just quality. Belden has never let me down for cable.

If your cable is "too short" then it is a design defect with either the electronics. Not saying it can't happen, but it shouldn't. This is why we have standards.
 
I did a test with both and found that Toslink does not have the bandwidth needed over longer distances (88Khz instead of 44kHz over SPdif 10m). This could be a problem of the plastic fiber or/and the optical transmitter/receiver. So it depends on the quality of the used components as pro stuff can run 2km over fiber (Single mode) with very high frequency.
 
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