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Question on how laserdisc audio works

Discussion in 'Archived Threads 2001-2004' started by Todd K, Apr 30, 2002.

  1. Todd K

    Todd K Second Unit

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    Hello,
    I have been caught up in what seems like a resurgence of the laserdisc craze. I have read through numerous threads here on the HTF, and was very impressed from what I learned about Dolby Digital from this FAQ:
    http://www.precisionlaserdisc.com/newfaq.html
    However, all the literature hasn't been able to answer one question for me, since I can't really see the back panels to any players. This question mainly revolves around discs that have AC-3 audio on them, and the players that can handle them. I know I may never even own a Dolby Digital laserdisc, but I feel the need for answers.
    -Were any DVD players ever made that have a built in demodulator, so that you could just hook up a digital cable from the back of the player to a receiver? I would assume not, since that would mean two digital outputs on one player, right? (One for AC-3 and one for the regular digital channels.)
    -How does the AC-3 signal get from the laserdisc player to an RF demodulator (or receiver with built in demodulator)? Do you need to have a player with an AC-3 out? (Or I seem to recall some people were able to create an AC-3 out for themselves?)
    -Related to the above, if the AC-3 signal is stored where the right analog channel is supposed to go, what would happen if you just connected the white/red R/L analog jacks from the LD player to your receiver? Wouldn't you just get sound out of only the left speaker and garbage out of the right?
    That's all, for now, I think. With the answers to these I think I will be able to sleep at night now.
    Todd
     
  2. JamesTR

    JamesTR Auditioning

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    My Pioneer 503 has a digital audio output in addition to the two analog audio outputs. I use the single digital to feed a digital input on my reciever specifically marked for laserdisc players. The AC3 or other digital signals come through that cable and the reciever deals with them from there. JimR
     
  3. Tim Hoover

    Tim Hoover Screenwriter

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    I've never seen a LD player with a demodulated DD output. The ones that output AC-3 use an RF connection with an RCA jack. These will be labelled as "AC-3 RF output." Some also have a fiber optic connection, used for passing encoded DTS or the digital PCM tracks. If you used the analog outputs, you would get awful noise from the right speaker if you selected the analog soundtrack on the player. LD players use a built-in DAC to output the digital soundtrack through the analog outputs - like a CD player.

    I hope I'm making sense with all of this, because I've been awake since 3am! Perhaps some of the other LD buffs can chime in with a little more coherence...
     
  4. Kevin P

    Kevin P Screenwriter

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  5. Todd K

    Todd K Second Unit

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    Thanks so much, folks. These were the answers I was looking for.

    I do have some follow up questions, though:



    Does this mean it's up to the listener to decide on the connections to their receiver? If only the left channel signal has usable material, you'd have to either send that left channel to both left and right, or activate some switch on the receiver that sent the left channel to all speakers, right?
     
  6. Michael St. Clair

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    You can typically tell the laserdisc player to output the Left analog channel to BOTH the L and R analog outputs (creating two channel mono). Same for the right channel.

    No player I know of will convert the analog outputs to optical...but a $50 box you can buy will.
     
  7. Rachael B

    Rachael B Producer

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    Todd, you need to go over to the home theater basics section and read Vince's HT basics thread. I wrote the LD section at the bottom of page 2. It's a long scroll down.
    Actually there was one player with an AC-3 demodulator as an option but it wasn't produced in much quantity. The hi-end MSB Silver, a Panasonic clone, used to have an option to have a demod box mounted on the outside, back of the player. Memorize this it could come up in Trivial Pursuit.[​IMG]
    Best wishes from Laserland!
     
  8. Matt Stone

    Matt Stone Lead Actor

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    I've got a question. Is there anywhere besides precisionlaserdisc where I can find an optical output addon for a reletively low price?
     
  9. Philip Hamm

    Philip Hamm Lead Actor

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    Doubtful.
     
  10. Rachael B

    Rachael B Producer

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    Matt, the only other place I know of is: www.msbtech.com
    I know they used to do this. I won't swear it's stille on their current mod list. Best wishes!
     
  11. Matt Stone

    Matt Stone Lead Actor

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    Hmm...they only appear to have the AC-3 RF upgrade...thx anyway though.

    I figure I'll just get a new player in the future if it's that big of a deal to me.
     
  12. Matt Stone

    Matt Stone Lead Actor

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    After more looking, I found it Rachael. But it's 385 bucks...yowza, so at that price I'll definitely just go with a new player if digital out is that important to me.

    Thx.
     
  13. Tim Hoover

    Tim Hoover Screenwriter

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