Digital audio output question

Discussion in 'Blu-ray & DVD Players & Recorders' started by dave_st185, Sep 5, 2007.

  1. dave_st185

    dave_st185
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    Is there a technical difference between a digital coax output and digital optical output in terms of bandwidth they can carry, re HD audio formats, particularly higher bandwith PCM signals?

    I've noticed that only the XE1 seems to have a digital coax output, and I'm using the only optical input on my processor for Sky HD, so I want a HD DVD player with digital coax, but would also prefer to buy a newer gen player than the XE1

    I was wondering if the reason most of the HD DVD players only have a digital optical output was performance or cost based?

    :hiya:
     
  2. Andy98765

    Andy98765
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    To get Dolby TRUE HD audio your AV amp must be able to decode it or it has to be connected to the AV amp with a direct 5.1 link (6phonos) so that the HD DVD can decode. If you say your amp has one exch optical and co-ax it sounds like a budget AV system. You should beable to still get DTS, Dolby digital though.
     
  3. dave_st185

    dave_st185
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    The processor's a Linn 5103 (approx £4k) so not quite low budget :)

    It's old though, but still an awesome stereo pre amp and excellent Dolby DTS and Digital decoder so I'm reluctant to upgrade it until I can afford something that will at least equal it's performance

    It can't decode the new Dolby HD formats, but it does process PCM signals, so I was wondering about digital coax outputs as I don't have any optical ones free
     
  4. telford_mike

    telford_mike
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    To all intents and purposes digital coaxial and optical are the same.

    Does your amp have 5.1 analogue inputs? If it does, you can let the XE1 do the decoding (which it does very well) and you'll be able to listen to the new audio formats like TrueHD.
     
  5. HeweyBoy101

    HeweyBoy101
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    Dave - does the Linn not have any 5.1 channel analogue inputs? If it does then you could avoid the digital connection altogether and let the player do the decoding, and still benefit from next gen audio.

    I personally use analogue for all my HD audio connections, as well as for DVD-A and SACD. Can't bring myself to replace my trusty Yamaha amp (much like you with your Linn). Also I don't trust HDMI digital audio to actually sound any better than analogue. I still use optical for Sky HD and coaxial for SD DVD though.

    Cheers.

    Mark
     
  6. Nic Rhodes

    Nic Rhodes
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    The 5103 is one of the really great processors and you should not get rid of it 'soon'. It doesn't have 5.1 from memory however so you are limited to coax or optical toslink. As had been said they are essentially the same and on this procesor is excellent. They are limited to DD 640MBS and DTS to about 1300mbs on the later models. Even with this lowley 'spec' you will find the 5103 will deliver on sound quality as much of this is about the quality of the digital and analogue engineering as opposed to playing the numbers game.
     
  7. dave_st185

    dave_st185
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    Thanks for the replys everyone

    Nic is correct, there's no 5.1 analogue inputs on the Linn just 4 coax and the one optical for the digital formats

    Thanks for the info re the coax and optical signals being essentially the same - I was beginning to wonder if there was an advantage to optical but I'll put the fact that only the XE1 has a digital coax output down to Toshiba doing a cost saving exercise

    It's nice to know the processor is thought of that highly, I'm quite keen to hear it with some HD sources, and this is where I might be getting confused so please correct away

    I was under the impression that players like the XE1 could output the audio either fully decoded via analogue 5.1, or as a purely digital undecoded Dolby True HD signal, neither of which the Linn will accept, or as decoded digital data in a PCM signal format, which the Linn will accept

    Am I mistaken about what a PCM signal is, and what quality of signal can be transfered from the player to the processor via it?

    If I have to 'settle' for just a 1.3mbs traditional dolby signal then I guess it's not the end of the world as it is rather sensational with a good DTS SD DVD soundtrack anyway, but if there's a way to improve on that, well you know... :)

    Thanks
     
  8. city fan

    city fan
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    The XE1 has both coaxial and optical outputs :)
     
  9. MikeK

    MikeK
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    I was under the impression that players like the XE1 could output the audio either fully decoded via analogue 5.1,

    Yes

    or as a purely digital undecoded Dolby True HD signal,

    No, although a firmware update to allow this is rumoured to be imminent, which will allow this over HDMI!

    or as decoded digital data in a PCM signal format

    Yes, but only over HDMI in multichannel - not coax/optical.
    For coax/optical it's 2 channel PCM only.

    AIUI, if you set bitstream for SPDIF, this model will downconvert Dolby TrueHD and DD+ to 640kbps vanilla Dolby Digital for transmission over coax/optical. It will downconvert DTS-HD to DTS for transmission over coax/optical. It won't do DTS-MA though, but then neither does any other player yet!
    Vanilla DD and DTS tracks will be output as is!
    If you set PCM for SPDIF, it will convert everything to 2 channel PCM.

    Not really much Toshiba can do about this - basically SPDIF is a very popular interface, but it's limited as to what it can do. Hi bitrate hidef audio is simply beyond it's capabilities.
    Even if it could do it, there are very few (if any) AV amps/receivers around, which could actually decode the incoming hidef SPDIF data anyway!
     
  10. dave_st185

    dave_st185
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    Thanks Mike, that makes things a lot clearer

    I guess multi channel PCM over digital coax is what I was hoping I could get from an XE1, it's a shame it's limited to 2 channel

    I'm sure I've had multi channel PCM into the Linn before from certain disks with my SD DVD player, but I guess it could have been the Linn forcing pro-logic from a 2 channel PCM input, so maybe not?

    It looks like the bitstream over digital coax will be the best option for me then, it'll be interesting to hear how that compares to a 'HD audio format ready' solution

    Thanks
     

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