10-bit/54mhz vs 12-bit/108mhz video DAC

Discussion in 'Blu-ray & DVD Players & Recorders' started by Dolbyz, Jul 27, 2005.

  1. Dolbyz

    Dolbyz
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    I'm planning on 'upgrading' from a Sony DVP-NS955v (DVD/SACD) to a Marantz DV6500 (DVD/SACD/DVD-Audio). Everything seems on par with each other - except for the formats (Marantz has added DVD-Audio) and the video DAC (Marantz is half that of the Sony - 10-bit/54mhz vs 12-bit/108mhz in the ony).

    Will it effect the video quality considerably?
     
  2. Thunder

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    Implementation ;)
     
  3. Dolbyz

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    I seriously must be having a bad day ... what do you mean by implementation?

    The other items I plan to use it with? If so, a 28" (72cm) 4:3 standard CRT television, connected via SCART with RGB signals. If this isn't what you meant, I've just embarressed byself ... ;)
     
  4. AML

    AML
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    I also dont get these single word answers mate.

    Perhaps they think we can read minds?

    The DAC you are talking about is indeed for video. It should in theory be better the higher it goes.

    My Denon 3910 uses a 14bit 216mhz Video DAC. (thats twice as high as the Sony one you mentione.)

    I guess the quality does go up the higher the DAC, but since I use the digital video outputs, I dont really know!

    I did see a big difference between my first DVD player which was only 10 bit 24mhz and my second player which was 12bit 108mhz. If that is the change you are making im sure you will see a big difference in quality.

    If you can I recomend you get a player with a digital video ouput as that makes an even bigger difference if you have a display that is capable of showing it.

    Otherwise use analog component with a 12bit 108mhz DAC.
     
  5. Sofa1

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    maybe it means numbers are nothing :lesson:

    on paper, it looks like 12/108 will have better results but it is not always the case. did somebody compared directly PQ between 10bit and 12 bits models?
     
  6. wolfgang

    wolfgang
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    I think what he is suggesting is it depend what each companies do with them that matters in the end rather then the spec sheet. Even 2 players with the same type chip could have very different performances and abilities like how the firmwares are written.
     
  7. Dolbyz

    Dolbyz
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    AML - My Sony is only 240 quid while you're Denon is 800 quid :p You should have THREE times the bandwidth, not only twice ;)
     
  8. Nic Rhodes

    Nic Rhodes
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    As DVD is 8 bit, to accurately represent it you need 9. To make things easier we call it 10. Anything more is just playing the numbers game.....Ask John Dawson.

    Ever wondered why the top scalers don't play these games, well quality isn't about how high these numbers are it is about the quality of the DAC and how it is implemented.

    Anyone fancy putting their 14bit 216mhz Video DAC against my lowly one in my Tag player?

    You can tell nothing by these numbers.
     
  9. Thunder

    Thunder
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    Bingo! :)
     
  10. Thunder

    Thunder
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    Ditto :)
     
  11. Dolbyz

    Dolbyz
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    Tag *drool*

    Now THAT'S what I want to get one day!

    Do Tag make nothing higher than 10-bit/54mhz then ... ?
     
  12. Nic Rhodes

    Nic Rhodes
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    [QUOTE John Dawson, ARCAM]
    I lecture on this stuff to the trade from time to time and I have to say there is a lot of marketing-ese (aka bullsh-t) deployed in video specifications in the same way that it is nowadays de riguer to have 24 bit audio DACs in audio equipment, when they typically don't deliver more than about 17 bits of dynamic range and sometimes a lot less. I could go on (but won't).

    DVD is an 8 bit video medium. In order to accomodate the sync pulses, colour bursts etc that also make up an analogue video signal derived from DVD it is easy to show that you need a "perfect" 9 bit video DAC to accomodate all this. In practice a well engineered 10 bit DAC will therefore do a more than satisfactory job. In terms of sampling frequency you need a minimum of 13.5 MHz for interlaced video and 27 MHz for progressive video. So for most purposes 54 MHz is sufficient, allowing gentler slopes on reconstruction filters etc.

    Having said that all the digital processing that goes on before the DAC inside the MPEG decoder needs to be at a significantly higher precision, say 12 bits or more. A lot will depend on how well this is done, redithered etc and it is nigh on impossible to find such information in the public domain, or even under NDA. However it is certainly true to say that MPEG decoders (the heart of all consumer DVD players) vary quite a lot in terms of absolute performance.

    I can tell you that the excellent Zoran Vaddis 5 MPEG decoder (the BGA version not the less expensive and less well specified 5E one) that Arcam uses in the DV78/88Plus/89 family has 6 x 10 bit 54 MHz DACs integrated into it and produces excellent video quality. I happen to know it uses 12 bit internal processing too. In further support of this argument the highly regarded and very expensive TAG DVD players also used the internal 10 bit DACs integrated into the Mediamatics MPEG decoder and were always praised for their excellent (interlaced only) video quality.

    We use an external 12 bit 208 MHz sampling video DAC/encoder on the DV79, with suitably readjusted filtering and the picture is arguably better than the DV78 but IMO the differences are not huge by any means. Like all such external DACs it is coupled back to the MPEG decoder via an 8 bit digital video bus.

    Of course the video quality also depends on having good properly buffered analogue reconstruction filters after the DACs and a set of proper 75 ohm buffers afterwards, plus noise free power supplies etc. IMO inexpensive and mid range DVD players rarely pay as much attention to these as is really required.

    Incidentally the minimum number of video DACs you need on a DVD player is 4 to provide RGB plus sync on composite video (i.e. to a SCART equipped display). Having 6 allows you to support s-video simultaneously (all Arcam players do this with interlaced video) but it is not essential in most set ups.

    In general you get what you pay for, but judging a player on the spec of its video DACs is like judging a car on the size of its engine - it affects the result but there are many other factors that determine how well the car actually performs and drives. There is no substitute for having a proper demonstration at a good knowledgeable dealer of either a car or a DVD player.

    And we haven't even mentioned sound quality yet :)

    HTH.

    John Dawson (Arcam)
    [QUOTE John Dawson, ARCAM]

    The above was posted here by John some time ago.
     
  13. Nic Rhodes

    Nic Rhodes
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    Tag a curates egg, has been very unreliable recently but sound and video are exceptional when it works, FLR MUCH better reliabilty IMHO, so BE CAREFUL about buying one, it is a bit like playing russian roulette
     
  14. liam_b

    liam_b
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    Not that I want to disagree Nic but Russian roulette is longer odds against something going pop! :devil:
     
  15. Cable Monkey

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    Your on! Bring it down to Birmingham at the weekend and I will make a side by side comparison with my Denon. It'll take me about 6 months to make a definitive decision! ;)
     
  16. Nic Rhodes

    Nic Rhodes
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    all demos in Cumbria, Tags don't travel too well ;)

    Liam, are you sure death rate on Tags is nearly 50% ;)
     

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