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Difference between DD5.1 EX and DD5.1 PLIIx?

Discussion in 'AV Receivers & Amplifiers' started by JIT, Jun 25, 2004.

  1. JIT

    JIT
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    On some DVD's the amp, Denon 3805, automatically selects DD5.1 EX whilst on others it is on DD5.1 PLIIx.

    What are the differences between these?
     
  2. dishdoc

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    My understanding of dolby PL IIx is that it allows a 5.1 or stereo soundtrack to be played through a 6.1/7.1 system.Its explained much better here, www.dolby.com/press/ce_pr_0309_plIIx.html

    Hope this clears things up for you :thumbsup:

    dishdoc
     
  3. Mr Bump

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    :lesson: Dolby Pro Logic IIx is still a matrixed surround, so it is taken simply from a stereo signal and the various channels are decoded from this. PLIIx is supposedly 7.1, but like any matrixed surround it isn't a patch on a true discrete mix. DD5.1 EX is a 'true' discrete 5.1 (each channel is a seperate signal) that also has a 6th 'center rear' channel matrixed into the L&R rear channels, that a 6.1 amp can pick out. This is far better than PLIIx, although still not as good as a 'true' 6.1 (DTS-ES is a true, discrete 6.1 - examples include the LotR Extended Editions - normal editions only have DD 5.1 EX). Just to muddy the water further, there is also a DTS-ES with a Matrixed center rear, just like DD5.1 EX (I *think* Final Destination 2 is one of these, but can't be 100% without checking) - amps will usually say either DTS-ES 6.1 Discrete or DTS-ES 6.1 Matrixed. Oh and there is also a DTS Matrixed surround like PLIIx, called DTS Neo. Confused yet? :zonked:
     
  4. MarkE19

    MarkE19
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    DPLIIx is still very new and everybody seems to be getting slightly different ideas on exactly what it does. This is my best guess at it:

    If you play a EX encoded disk then the 3805 detects it and plays it as recorded - 6.1 channels.
    If you play a standard DD 5.1 encoded disk then DPLIIx kicks in and creates its own surround back channels from the other channels that are being decoded as DD. So you still get the full quality DD for the 5.1 mix, but also get the DPLIIx creating the surround rear channels.

    Well I know what I mean - Has that made it any clearer to anybody else :confused:

    Mark.
     
  5. Mr Bump

    Mr Bump
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    No, because that isn't what the 3805 does - if you give it a dd5.1 disc it plays it as dd5.1, not PLII or anything else. The PLIIx only seems to come up on dd2.0 (stereo) sources, which indicates that it is just another fully matrixed surround - just one that is supposed to be 'better'. But IMO that's like saying a better VCR - it's still a VCR no matter how good it is. Matrixed surround will never be a patch on true discrete surrounds.
     
  6. Mr Bump

    Mr Bump
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    Okay, I've had a read of the 3805 manual - from what I can make out, all PLIIx is is an 'enhanced' version of normal PLII (which is itself is just an enhanced PL).

    Okay, let's get one thing straight - ProLogic works from a stereo signal. When the stereo signal is mixed, they take the surround channel and center information and place it in a certain area in the mix - a PL processor then knows to 'pick out' sounds from these parts of the mix and send them to certain speakers, based on where in the mix they are placed. This is very different to Dolby Digital and DTS, where each channel (speaker) is a seperate signal. From what I can see, PLII and PLIIx have no difference in the way the stereo signal is mixed - it is done in exactly the same way as it was for ProLogic - the only difference is the way the signal is processed by the amp - with PLIIx they have tried to make it so that the signal fills a 7.1 speaker setup in a reasonable fashion - but that is all it is - the processor deciding what to do based on a strict set of rules, rather than the encoding dictating where the sounds go, as a discrete mix (such as DTS-ES Discrete) would do.
     
  7. JIT

    JIT
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    MarkE19

    That's what i think is happening too.
     
  8. Mr Bump

    Mr Bump
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    So you're telling me JIT that whenever you put a Dolby Digital DVD in your player, it doesn't come up DOLBY DIGITAL on the 3805, it comes up Pro Logic IIx? Because it sure don't do that on my 3805.....
     
  9. JIT

    JIT
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    No, some come up "Dolby D EX" whilst others show "Dolby D PLIIx".
     
  10. ShinObiWAN

    ShinObiWAN
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    Both MarkE19 and Mr Bump are correct on this.

    DPLIIx can be used in 2 ways:

    (The one MarkE19 suggested)
    Play a DD5.1 disc and you do indeed get matrixed full range rear channels created by the DPLIIx decoding algorithms, so in essense you have 5.1 channels of discrete information plus your rears adding ambience to create something like 7.1 sound. I suppose what I'm trying to say is that it doesn't add any extraneous information to the existing 5.1 channels but only adds 2 discrete rears, nothing less and nothing more.

    (The one Mr Bump suggested)
    Use DPLIIx with stereo signals and again it will provide you with 7.1 but the center, side and rear surrounds are all using information derived from the 2 channel audio. Not nearly as impressive as the above example but effective non the less.

    Either way JIT, I would use DPLIIx for 2 channel and Dolby Surround films. And when using DD5.1 engage DPLIIx at you discretion, though on some films you will be pleasantly surprised at how good the extra rear channels are when DPLIIx is engaged.
     

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