What happens to 5.1 signal in a 6.1 system?

Discussion in 'Archived Threads 2001-2004' started by Ryan Tsang, Jan 25, 2003.

  1. Ryan Tsang

    Ryan Tsang Second Unit

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    If the receiver/processor is selected to one of the 6.1 formats, is there output from the rear center(s) when playing a 5.1 soundtrack?

    or will the receiver/processor not allow you to select 6.1 when it detects a 5.1 signal?

    Thanks!
     
  2. Michael Reuben

    Michael Reuben Studio Mogul

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    There is currently only one "6.1" format, known as DTS-ES Discrete, and it only exists on 23 titles. All other so-called "6.1" titles are merely 5.1 titles from which a decoder synthesizes an additional channel from the left and right rears. Most decoders will happily apply the same processing to a title regardless of whether the track has been specifically encoded for it. Results vary, depending on the mix and individual taste.

    M.
     
  3. Steve Schaffer

    Steve Schaffer Producer

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    Michael is technically correct.
    DTS ES Discrete is the only format with a discretely encoded rear center channel. DD-ES and DTS-ES Matrix formats are specifically coded to derive a rear center channel from the two regular surround channels, similar to the way regular Pro-Logic coding got a front center and surround information from a 2 channel source. It's not discrete but works fairly well.

    Also as Michael stated, most all DD-EX/DTS-ES decoders will synthesize a rear center from 5.1 material that lacks the specific ES or EX matrix rear center coding, just as pro logic decoders would attempt surround decoding of non-pro logic encoded 2 channel sources.

    How well this works is probably going to vary by source material and/or the particular processor in the pre-pro or reciever.

    I have a Pioneer VSX-45TX and use EX/ES mode for all the regular 5.1 movies I've played, with very nice results. Many of the movies with non-EX/ES coding still playback with a very convincing rear center effect, and I've yet to find one that sounds better with the EX/ES matrix decoding turned off. I've even used it with DPLII processing of 2 channel sources (Tomb Raider from Directv) and gotten nice results.
     
  4. Ryan Tsang

    Ryan Tsang Second Unit

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    Thanks guys! I plan to upgrade my Acurus ACT-3 to 6.1 and by the sounds of it (no pun intended), I'll leave 6.1 decoding on at all times.
     
  5. JamesKr

    JamesKr Agent

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    Don't forget about 7.1! [​IMG]

    I have two rear channels which replace a rear center. The rear channnel speakers are about 5 feet apart. To the best of my knowledge, 7.1 plays the same sounds from both rear channels as if they were both rear centers. The 7.1 format gives a more immersive rear sound than 6.1 does due to the dual channels.
     
  6. Ryan Tsang

    Ryan Tsang Second Unit

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    jameskr: You're absolutely right. I too, would use two rear center when the time comes.


    There seems to be an inconsistent use of terms, and it can be misleading when "7.1" is made to sound like a format.
    I'm not counting Logic 7.

    6.1 describes the number of channels used (discrete in DTS-ES, matrixed in THX-EX and DTS-ES matrix)

    7.1 describes a system using two rear center speakers, and is based on number of speakers used.

    Yet, Dolby advocates the use of two rear centers, to eliminate possibility of the "reversal" phenomenon. So in practice, an ideal setup for 6.1 playback is 7 speakers + sub(s). So why the 7.1 designation at all? Just call it 6.1 and let the users decide how many center rears to use in their setup. We don't call our systems "5.2" if we run two subs do we?
     
  7. Scott Merryfield

    Scott Merryfield Executive Producer

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  8. Michael Reuben

    Michael Reuben Studio Mogul

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  9. AaronBatiuk

    AaronBatiuk Second Unit

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