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HDCD question (for Steve)

Discussion in 'TAG McLaren Audio Owners' Forum' started by Plump, Nov 4, 2004.

  1. Plump

    Plump
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    Hi,
    I have quite a few HDCDs and I was always wondering about following crazy thing.

    I own both DVD32R/AV32RDP and Arcam Alpha9CD.
    In normal CD replay difference is not significant, both being great CD players, but when listening HDCDs I strongly prefer Arcam. I did few blind tests and was able to distinguish difference with fairly high margin. First I was thinking there was gain problem somewhere. Therefore I recalibrated everything (voltmeter + testCD) to match the gains (output to the amp) and funny enough I felt even bigger difference afterwards.

    I assume my units work fine, so the question would be why? Maybe Steve who programmed code into Sharc could giuve an answer here. Or is is just my imagination.....
     
  2. Stevesky

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    Firstly I assume you have both players connected digitally to the AV32R, rather than using the analog outs of the Arcam.

    If so then the only possible difference would be jitter based and this would affect non-HDCD encoded discs. If there was a data difference between the two players then HDCD wouldn't work as it's encoded into the LSB's of the audio data. Does the HDCD indicator on the AV light up when HDCD discs are played on each player?
     
  3. Plump

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    no, sorry for being not specific
    Arcam goes into analogue in and DVD32R, well, ... no big choice how to connect it!
    and yes, HDCD tag comes on when source DVD32R
     
  4. Stevesky

    Stevesky
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    Is the Arcam connected via the 5.1 bypass, or a normal analog input?

    All I can think is that when decoding HDCD the process increases CD headroom by 6dB. To avoid leaps in volume the AV32R automatically reduces the volume by 6dB, I'm not sure if the Arcam CD player will. Also if connected via a normal analog input the technical performance will be far lower than the DVD32R feed as it will be going DA->(AD->DA) rather than just DA.
     
  5. Plump

    Plump
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    I actually tried both, bp and analogue in. Currently I am using analogue in (+TMREQ)
    First I also thought it might be linked to those 6dB but after levels were matched it should not be the case I guess.

    Could it be some decoding difference Sharc vs. PM HDCD chip in Arcam?

    I must add here I do not think I have perfect hearing, at least not so good to be able to hear that AD/DA conversion or for an example to differ between digital cables...
     
  6. Stevesky

    Stevesky
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    I don't know then. If I find 5 mins I can do a quick sanity check on the HDCD decoder but when my grubby little fingers last touched it on v4.31 it was ticking along quite nicely.

    Also all potential performance gains of HDCD would be lost if it's fed through a AtoD->DtoA....
     
  7. TaxHamster

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    There should be no difference between the decoding in the two units, all HDCD products have to be certified.

    The Arcam uses the PMD100 device, so could be using either analog or digital gain scaling (required to handle the 6dB peak extension) controlled by the PDM100. The TAG definitely uses analog gain scaling. Was your test CD playing a HDCD encoded tone when you did your calibration?

    Also, I thought the Arcam Alpha 9 had a digital out - have you tried your "blind" test with it connected digitally?
     
  8. Plump

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    Hi,
    yes of course, test CD had HDCD section with a test signal. I am not a professional for sure but also not a novice in this area.

    I also tried digital out from Arcam and in that case it was sounding pretty the same. I was actually able to spot the difference only when used Arcam analogue output.

    It might be something wrong in my setup, but I can not determine what. I was only surprised such a difference was there only when listening HDCDs.

    :oops: forgot to thank you for your answers!
     
  9. TaxHamster

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    Apologies, it wasn't clear in your original post that you had used an HDCD signal and that when connecting both sources digitally, there was little (or no) difference.

    Arguably, the TAG software decode (21065/21161) & the Arcam hardware decode (PMD100) should be the same, but.....

    As Steve says, the A-D, D-A process in the AV32R would remove most of the benefit of the HDCD process, but if you prefer the sound, go for it! :)
     
  10. Plump

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    Thanks All :) !

    I never comment tastes, it was only surprising to me ther was some clear difference (also thru bypass without AD->DA conversion) between those two units. I will go to my sister later today and take her Arcam CD23 for the test, maybe my Alpha 9 has something. You never know it with electronics!

    Good (or maybe bad) there are just a few HDCDs outside.
     
  11. Miron

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    Hi!
    I use AV32R (SP) and at the moment I have one Arcam 9CD here too.
    After reading this thread I made short listening check and found no difference at all. I haven't done any gain matching myself but apart from slight level difference I feel both decoders do the same job.
    Hope this helps.
    Regards
    Miron
     
  12. Stevesky

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    Hi Guys,

    Had chance to do a quicky check on the HDCD implementation on the AV192R (same as 32DP) and it all seems to be fine.

    On track 2 of the Pacific Microsonics process test disc I also checked that the encoder gave out the unclipped sinewave, while if I switched off HDCD decoding (shift+9 on remote) it gives a clipped version.

    Performance wise the THD+N (20-20K bandwidth, 1kHz ref.) of the AV192R was giving a healthy -99.2dB on HDCD material, -100.8dB THD+N on 48K/24bit material was the best my unit could deliver from a digital input.

    On an ARCAM CD23 that I had access to gave -94.2dB THD+N on HDCD material, which is a tad low, but decoding appeared to be ok. All measurements done on an Audio Precision System 2 and waveforms eyeballed on a Tektronix 2024 storage scope.
     
  13. Plump

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    Thanks Steve,
    I did another check with CD23 and it was really as you say. Hardly any difference to AV32R

    There must be something wrong with HDCD on my Apha 9. Thanks for your efforts, Arcam helpdesk will get my call today.
     
  14. Plump

    Plump
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    And of course I apologize for the confusion I made. :blush:
     

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