How does the Yamaha rx-v2600 decode the signal

Discussion in 'Amps, Pre-Pros & Receivers' started by starflight, Dec 17, 2007.

  1. starflight Junior Audioholic

    starflight
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    Ok guys,

    I haven't bought a new receiver for a long time. My previous receiver to this Yamaha RX-v2600 was a Kenwood Sovererign series VR-3090 and I absolutely love it still but now that I have a new place and a new HT setup, I am starting to familiarize myself with new technology.

    What is confusing me about this receiver is that the GUI seems to let me choose whether I was to decode using Dolby Prologic, Dolby Prologic II or DTS:neo. regardless of what media is, I still can choose can kind of decoding. So if I'm watching a DVD movie that either has DTS 5.1 or Dolby Digital 5.1, I typically choose DTS 5.1 track. In my old receiver, if I chose DTS5.1 as the sound track, it would automatically select DTS decoding and it would be it. But now I can choose anyone I want on the RX-V2600, is that right?

    Also, does Dolby Digital changed its name to Dolby Prologic II? I'm kind of confused.. I my older receiver, Dolby Prologic and Dolby Digital (AC3) was two different beasts, with Dolby Digital sounding way better. Please enlighten me on this. Thanks.
  2. MDS Audioholic Spartan

    MDS
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    Dolby ProLogic, PLII, and DTS Neo:6 are all matrix decoders. If the source was encoded with Dolby Surround the matrix decoders just extract the extra channels that were placed in the recording by the encoding process. If the source was not surround encoded (like 2 channel analog or PCM) then they synthesize the extra channels; eg. to create 5.1 from 2 channels it will take out of phase information from the front channels and send it to the surrounds after a small delay and it will sum the front channels and send that to the center. The algorithms are all slightly different in how they accomplish it but that is the gist of it.

    Dolby Digital and DTS are 'discrete' formats - meaning they have separate discrete channels encoded and the DD/DTS decoder just extracts each channel and routes it to its respective speaker.

    The reason you can choose PLIIx when playing a DD 5.1 disc is that PLIIx can convert DD 5.1 to 6.1 or 7.1. PLII can convert any analog or digital 2 channel format to 5.1. PLIIx can convert any analog or digigital 2 channel format to 6.1 or 7.1. Some receivers will also let you layer PLII over DTS.

    If you only have 5.1 speakers connected you would not be able to choose PLII or PLIIx when playing DD 5.1 because it is already 5.1 and there would be nothing for the decoder to do.
    MDS,
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  3. starflight Junior Audioholic

    starflight
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    Thanks very much for the descriptive answer. I do have 5.1 speakers hooked up to my RX-v2600 out of the 7.1. I did not know about PLIIx being able to convert from 2 channel to 5.1 or higher output. That's very cool an all. I'm playing some movies from my PS2 which is connected via an optical cable to the receiver. When I choose DTS5.1 soundtrack, I still seem to be able to choose the decoder mode to be PL or PLII. I thought that if I choose the audio track to be DTS5.1, that the receiver would automatically detect that it was a DTS5.1 and stick with it and not let me choose otherwise...

    I wonder if my PS2 is outputting the audio correctly? If I go into the information section of the onscreen display for the receiver, should I see PCM if 5.1 sources are going into the receiver? I'm just wondering if there is something wrong with the way my ps2 is sending audio to the receiver.
  4. MDS Audioholic Spartan

    MDS
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    The receiver should show something like: DD 3/2.1 or DTS 3/2.1 for 5.1 DD or DTS. If it is PCM it will probably show the sampling frequency; eg my receiver would show fs: 48 kHz if the DVD player were outputting PCM.

    The PS3 should have a setting similar to a DVD player that allows you to choose 'bitstream' (sometimes labeled 'raw') or PCM. If it is set to PCM, the player decodes and downmixes to 2 channel PCM. If it is set to bitstream, it just sends the bits untouched to the receiver and the receiver does the decoding. If the receiver's display shows PCM or a sampling frequency, the output of the player is set to PCM.
    MDS,

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