Fiber optic differences?

Discussion in 'Location Recording' started by Sonarerec, Jan 16, 2005.

  1. Sonarerec

    Sonarerec Guest

    Now I need optic cables to tie my Myteks to the soon-to-arrive Alesis.

    I would like to hear opinions on various optical cables that address:

    - price

    - ruggedness

    - SOUND (dare I ask?)

    Rich
     
  2. FifthCircle

    FifthCircle Well-Known Member

    I'm going to go against the grain and say that cables for a digital transmission won't matter- especially in a well clocked environment. When you monitor on your DAC-1, Rich, you'll find that all the issues created by jitter seem to disappear. As long as the bits are there...

    While I haven't used the Alesis, I will say that if you can run clock as well as the signal into the recorder, you'll have better digital stability. ADAT does have jitter issues and clock data can be suspect. A BNC cable can save a world of hurt when it comes to interfacing everything.

    --Ben
     
  3. Simmosonic

    Simmosonic Active Member

    I'm not going to go so far against the grain, but I am going to say that digital transmission shouldn't make a difference! The better your clocking and interfacing, the better off you're going to be.

    When it comes to fibre optic cables, I've heard all sorts of reports about jitter and so on, and I'm not agreeing or disagreeing with them. I've had some nasty experiences with fibre myself, in the early days (er, 1992), but I was not able to test them back then so it remains inconclusive. Was it jitter? If so, was it due to the cable? The interface? Or what? The only thing I knew for sure back then was that a particular electrical SPDIF connection sounded far superior to a particular optical SPDIF connection between the same two devices (a DAT recorder and a stand-alone CDR).

    As Ben says, your DAC-1 will rid you of all those problems (if they exist). If it doesn't, then either it's not jitter, or you've already encoded it into the analog signal at some earlier point in the chain.

    Unless the clocking is terrible to the extent that you're losing bits, then the real problems caused by jitter are:

    1) Making it sound harsh or grainy, causing you to compensate with EQ (or similar) for things that don't really exist.

    2) If you convert back to analog at some point in the production process (e.g. to run the sound through an analog processor), and the DAC does not do a good job of overcoming the jitter, then when you re-encode to digital you will capture the harsher, grainier sound and be stuck with it. No converter can remove it if it exists in the analog signal...

    I don't think there's any harm (except financial!) in buying good quality cables and connectors, whether electrical or fibre optic. The trick lies in being able to tell a good one from a bad one. There are many mediocre cables sold for outrageous prices in hi-fi shops, and many fine cables sold in hardware shops (and similar) for next-to-nothing.

    As for ruggedness, what do you intend to do? Is it something you're going to be moving around? Continually plugging/unplugging? Or is it something that is going to stay put and permanently connected?

    It is nice to buy good connections, but are the connectors built into the equipment going to justify it?

    The nice thing with fibre is that you can tell by looking whether or not it is rugged. This is much harder to do with wire because you usually can't see the solder joints or the internal wires.

    Questions, questions, questions...

    - Greg Simmons
     

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