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Frustrated with Dolby Pro Logic II

Discussion in 'AV Receivers & Amplifiers' started by Ikki, Oct 23, 2005.

  1. Ikki

    Ikki
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    I run the sound for my AV setup though a Yamaha RXV-430RDS receiver. Most of the audio feed is from a Freeview box which outputs stereo or Dolby Pro Logic encoded stereo.

    In use with DPLII engaged, most of the time the sound comes from the centre speaker with only a small contribution from the front side and the rear speakers. This effectively means that most transmissions become mono and not 'surround sound'.

    Am I expecting too much that the receiver can produce decent stereo / surround sound from a stereo source while it is in DPL II or DPL mode rather than something akin to the pseudo mono sound that it seems to output most of the time? Even obviously stereo transmissions like Jools Holland's Later exhibit the above characteristics. I have tried many combinations of settings, without success.

    Any ideas? :lease: (non expensive :eek: )

    Just a p.s.

    It's fine in full Dolby Digital or DTS from a DVD.
     
  2. Knyght_byte

    Knyght_byte
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    if a program is only recorded in a basic mono or stereo, PL2 isnt really that useful, as you say, most of the stuff ends up coming out the centre channel.....this happens mostly on analogue TV broadcasts
    if its a Dolby Surround broadcast (like a lot of Sky stuff) then it can be a lot better....

    you might wanna try some of the in-house DSP modes that your amp offers (if it has any, i dunno what your amp is capable of)......if its a simple amp it will probably have things like Church, Dance Hall, Disco etc as the names.....or if its more expensive amp then it will have probably 10 or 20 different ones, some based around TV, some around films, some around games, some around music etc.....

    if you have DTS:NEO6 then try that, it can be a bit better than PL2 with some TV stuff but not always...
     
  3. pragmatic

    pragmatic
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    The degree of pro logic decoding may depend on the unit its self, i have a 2500 and plIIx and neo 6 produce a very good sound involving the centre for vocals the fronts for music and the backs are often used for ambient effect. This was while beeing connected to telewest cable box and as such it had digital sounnd quality, was pretty much always nicam or dolby pro logic recording.

    For example on star gate or enterprise the 'hum' of the station or base would come through the rears. On adverts this is further used for music too, although i suspect that most of this content has been recorded in pro logic so the amps getting a little help.

    When you say non expensive, how much we talking about, as without getting a new processor or better source (make sure its got nicam atleast, i.e. go through a video first if its analuage terestrial).

    As your using a frewview box i can't see there being a source problem, what model is it?

    Without changing your reciever you could try 5 channel stereo(you may enjoy it more), or one of yamahas dsp on the pro logic mode.

    I must say when i had a 620 and used a standard analoge terestrial signal i can't remeber being bowled over with prologic, unless the content was written for it, but i assumed it was because it was the origional pro-logic which everyone said was pretty poor.
     
  4. Ikki

    Ikki
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    Thanks for the replies,

    What you have said concurs with my own thoughts. When watching something like Enterprise which is PL encoded, the effects are ok if not stunning. I guess the decoder is a bit lacking in the ability to create pseudo surround from a stereo program. It's not the source that's the problem (a Humax PVR8000T) although that may be upgraded soon. I think that the receiver may be the area where improvements could be made as it is about four years old now and doesn't have the latest decoding modes. I think that some research is in order.
     
  5. Mandel

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    Unless the material is actually Dolby Surround encoded I think you are better using either Prologic 2 music mode or DTS:Neo. The music mode will stop the centre channel taking over so much of the sound and will disable some of the steering logic that you don't really want turned on for non-encoded material.
     
  6. Steve.EX

    Steve.EX
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    Gents.

    I think there is something amiss here.
    It sounds very much like, for what ever reason, the decoder is acting as if fed with a mono (or more correctly 2 channel mono) signal.
    In either pl or pl2 modes the center channel outputs any signals that are common to both front left and right channels, this is commonly dialogue which along most music cd's sits "center" of the stereo image.
    Although (again for whatever reason) digital broadcast stuff does indeed seem less phasey than it's analogue brethren there should still be lots and lots appearing from front and rear L+R. Even Coronation Street has loads of presence! Channel 5 always "seems" to have far more by way of surround presence in my experience, whether this is attributed to broadcast bit-rates is unknown to me but i find consistantly that action films broadcast on Ch5 are as good as the surround experience gets on digital tv.
    My quite extensive listening/comparisons of these sources leaves me in no doubt that at it's very best, freeview sourced stuff (i used a Pace Twin via Toslink to a Tag 32DP) is barely the match of the good old analogue equivalent.
    PL2 is notoriously fussy about about poor source feeds. I remember when PL2 arrived and people were complaining of all sorts of weird and wonderful effects eminating from rear channels which, IIRC is directly linked to the PL2 algorythm not liking the lowly bit-rate sourced stuff thrown out by Freeview, particularly by (but not exclusively) the cheap-seat channels.
    This is not exclusively related to cheap kit, my 4k processor is more than happy to exhibit PL2 oddities and i have heard on better kit than my own. In this respect vanilla PL and Neo6 seems to be more stable.
     
  7. Steve.EX

    Steve.EX
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    I wouldn't pay to much attention to "surround encoded" broadcast material.
    You should get something (surround wise) from pretty much anything circa late eighties. Commoner-garden advertisements often have sublime sound.
     

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