Pro-Logic II and Sibilance

Discussion in 'Archived Threads 2001-2004' started by Neil S. Bulk, Jan 14, 2002.

  1. Neil S. Bulk

    Neil S. Bulk Screenwriter

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    I have a 10 year old Fosgate DSL 2 Dolby Pro-Logic surround sound decoder, and while I love it, it has a few operational quirks, and is sometimes a pain to use. I mainly only use the Pro-Logic mode as many of the other matrix modes have to much surround activity. When watching movies, the loud action sequences can be very exciting when the surrounds are in stereo or are not bandwidth limited, but in quieter, dialogue driven scenes, there seems to be artifacts popping into the surrounds. This drives me crazy, so I always turn back to the Pro-Logic mode.

    Now I'm interested in getting a receiver with Pro-Logic II. My guess is that since it is approved by Dolby, and is many generations away from the earlier Fosgate unit that I have, the matrix decoding is probably much better. Has anyone used Pro-Logic II and noticed occasionally a bit of dialogue leaking into the surrounds, or is the decoding so good, that this does not happen? Since this decoding meets Dolby's specifications, it probably doesn't happen, but I just want to know others experiences before I buy a new receiver.

    Thanks for the help!

    Neil
     
  2. GregK

    GregK Screenwriter

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    Hi Neil,

    As no one else has yet to chime in on this subject, I'll

    tell you my listening observations with DPL-II. With the

    certain audio material, yes - Sibilance does still occur.

    ..But it seems that it typically happens when listening

    to material that is even slightly dated or whenever the

    phasing is anything less than perfect. (Cable, some older

    LDs, older VHS, older films, etc,) Any *slight* bit of

    phase drift will introduce high frequency phase shifts.

    As you may know, when running full bandwidth surrounds

    in a matrix mode, sibilance will almost certainly pop

    up sooner or later, unless a band-aid of some sorts is

    used (HF filter, mono phase coupling of matrix derived

    surround channels etc). In DPL-II's case, two "band-aids"

    are on hand. The DPL-II Music Mode uses a gentle HF filter

    (nothing like the harsh DPL-I filter) that can help with

    slightly less than ideal recordings. Then there's the DPL-I

    retro mode still on tap- which is still rigged for "worst

    case scenarios": The surrounds are limited to 7khz and

    summed to mono. I think the advanced DPL-II logic action

    is active in the retro mode though, but this may vary from

    receiver to receiver.

    So my advice is to set your DPL-II mode to music or retro

    if sibilance gives you problems on a certain title.
     
  3. Neil S. Bulk

    Neil S. Bulk Screenwriter

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    Thanks Greg! I'm probably getting a Yamaha HTR 5490, so I'll post my findings with Pro Logic II after I do some intense listening. I'm itching to hear Raiders of the Lost Ark with this mode.

    Neil
     

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