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  1. #1
    RGA
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    Hi Resolution Audio article which may be helpful..

    for those trying to figure out which DACs to get.

    Audial :: USB 2010 (page 1)

    As an aside some of the big designers in this field - the head of AMR "DSD is a single bit, 128 times oversampled format with extreme amounts of noiseshaping added. Some people (including myself) consider it "defective by design".../...DSD is precisely such a 2-Level system with 128 possible values for a 22.7uS Sample period (that is CD), in other words it is a 7 Bit - 44.1KHz equivalent natively, without noise-shaping. This is well below what CD is actually capable of.

    And noise-shaping in Digital systems is equivalent (but much larger in magnitude especially for single bit systems) to what I like to call "fuzzy distortion" in looped feedback circuits.../...Many modern DAC's do replay DSD/SACD, however most add digital filters to the DSD stream to clean up at least some of the noise, with predictable results. Anyway you need a DAC Chip that is designed to handle DSD in order to play back DSD.

    Or you need to convert DSD to PCM, which to me suffices with 88.2KHz sample rate and 20 Bit to contain all actual information in DSD (as opposed to the all the supersonic noise from the noiseshaping), but is considered by the current bunch of DSD advocates a major lese majesty and utter heresy (Ed Meitner took the same view and some of earlier SACD Players in fact converted DSD to double speed CD Standards PCM).

    At any extent, you can now use 176.4KHz and 24 Bits, so you are guaranteed to loose nothing except the ultrasonic noise, which seems to be what DSD fan's really like (I know, another utter heresy). Several Software Players now exist that can transcode DSD on the fly to PCM during playback, so no need to convert the File itself. The same can now also be applied to decoding HDCD, though I personally transcoded all my HDCD's to 20Bit/44.1KHz PCM."



    I'm getting a headache.
    Last edited by RGA; 10-01-2012 at 05:29 AM.

  2. #2
    Shostakovich fan Feanor's Avatar
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    Yes, the DSD vs. PCM thing has always been beyond my technical comprehension. Frankly I'd be happy with either -- as I would with hi-rez DTS and/or Dolby Digital.

    Going back to early DVD-A vs. SACD days, technical opinion seems to favor DVD-A, i.e. PCM at 24/96 or 24/192. SACD became predominant (relatively speaking) mainly on account of the labels that adopted it.

    Sir Terence has mentioned the professional format, DXD, which is PCM at 24/352.8. But apparently there are higher rez DSD formats, viz. DSD-wide and DSD Pure whose virtues I don't pretend to know or understand.

    I have a few dozen SACDs. I can't appreciate them fully in my stereo system on account of my crummy old player; I can listen to them multi-channel in my HT system but the amp & speakers lack the resolution of fully appreciate them.

    I have some hi-rez downloads from HDTracks. Based on limited examples these file sound better for sure than CD (in my stereo system). Most are SACD rips to 24/88.2, so I don't know what that tells us.

  3. #3
    M.P.S.E /AES/SMPTE member Sir Terrence the Terrible's Avatar
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    Quote Originally Posted by Feanor View Post
    Yes, the DSD vs. PCM thing has always been beyond my technical comprehension. Frankly I'd be happy with either -- as I would with hi-rez DTS and/or Dolby Digital.

    Going back to early DVD-A vs. SACD days, technical opinion seems to favor DVD-A, i.e. PCM at 24/96 or 24/192. SACD became predominant (relatively speaking) mainly on account of the labels that adopted it.

    Sir Terence has mentioned the professional format, DXD, which is PCM at 24/352.8. But apparently there are higher rez DSD formats, viz. DSD-wide and DSD Pure whose virtues I don't pretend to know or understand.

    I have a few dozen SACDs. I can't appreciate them fully in my stereo system on account of my crummy old player; I can listen to them multi-channel in my HT system but the amp & speakers lack the resolution of fully appreciate them.

    I have some hi-rez downloads from HDTracks. Based on limited examples these file sound better for sure than CD (in my stereo system). Most are SACD rips to 24/88.2, so I don't know what that tells us.
    DSD pure is just basic DSD edited completely in the DSD domain on a DAW.Can't really do much except edit before the system runs out of resources. So it is edited at 1bit 2.8224 MHz all through the process. DSD wide is DSD 8bit 2.8224 Mhz which allows for equalization, balancing, panning, and has the overhead room to process it, and then return it to a standard DSD stream.

    You can either record in DXD, or us it as a editing tool(balancing, panning, editing, EQ) for DSD.

    There is also double rate DSD128 which is also a 1 bit system but operates at 5.6Mhz instead of the normal 2.8224Mhz of standard DSD.

    All of the DSD variants are really recording side formats, as all lead back to basic DSD after all post processing is done.
    Sir Terrence

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  4. #4
    Audio casualty StevenSurprenant's Avatar
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    Great article!

    One of the more interesting points he made, from my perspective, is how filtering affects what we hear, i.e...

    However, this intuitively still a bit bizarre looking response corresponds pretty well to some subjective qualities, traditionally associated to the transient response of the system. Namely, all the brickwall FIR filtered digital systems that I've heard up to date, had big problems conveying natural decay and space, and timbre. In addition, they are prone to boost intense and echoing, false"details", which is rather only imitation of desirable system's ability to convey unrestrained resolution, which should appear within the overall coherent artists' performance. And there was no brickwall filtered digital system that was able to convey natural sound stage, with precise instruments positioning, and natural instruments dimensions. Instead of such a natural space, they boost artificial reverberation of undefined spaciousness, which often swamps the instruments themselves.
    Twice, I've heard soundstaging that was extremely defined, where you could see where people were on the stage and believe that you could walk between them. This was about 17 years ago and the gear they used was Theta Digital on one system and Spectral on another. I have no idea of the technical aspects of either piece. Both times this was with a CD provided by the store owner, which I assume, at that time, was bluebook.

    All the other very good CD playback units I auditioned didn't produce such pinpoint imaging, but did well at creating a layering effect from front to back. On a good CD recording, that's what I normally hear at home. Another way of saying this is that with the Theta and Spectral gear, I could see the "space" between each instrument and with the other gear, not so much.

  5. #5
    M.P.S.E /AES/SMPTE member Sir Terrence the Terrible's Avatar
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    Rather than looking at imaging in a vacuum, one has to understand the proper microphone setup has to be used to achieve the effect. If some CD do not produce pinpoint imaging, it is likely the microphone setup does not allow for the effect to exist, or it minimizes it. The reality is, there are plenty of well recorded classical music CD I have that do support both lateral imaging, and depth to the recording.

    The reconstruction filters are not always the issue, sometimes it is in the recording itself.

    Imaging is profoundly recognized in the frequencies between 800 hz and 4khz - well within the bounds of CD's bandwidth. At 10khz and above which is CD's weakness, there is only harmonics, air, equipment and ambient noise of the recording space. Couple that with the fact that our hearing is less sensitive the higher you get in frequency(around 10khz and above) and at lower frequencies below 800 hz as well), and that supports the fact that imaging is not determined by high frequencies, or by low frequencies as well.

    Also keep in mind these conclusions are only based on the authors experience. Yours may differ entirely.

    Can anyone explain to me what is a Bluebook CD?
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  6. #6
    Audio casualty StevenSurprenant's Avatar
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    24/192 Music Downloads ...and why they make no sense

    I thought that you might enjoy this. I'm not taking sides because I don't know.


    24/192 Music Downloads ...and why they make no sense:
    24/192 Music Downloads are Very Silly Indeed

  7. #7
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by StevenSurprenant View Post
    I thought that you might enjoy this.
    By its length, I gather that was the "full" Monty. Monty who?

    As one who has read considerably about the Boston Audio Society test along with commentary by John Atkinson and one of E Brad's friend's Tony Lauck (who is an engineer), I was curious to see his commentary on that.

    "BAS conducted the test using high-end professional equipment in noise-isolated studio listening environments with both amateur and trained professional listeners."

    Now that's pretty funny! BTW, the "high end professional" Universal players used for high resolution playback were a Pioneer 563A with a suggested retail price of $249 and a Yamaha DVD-S1500 that retailed for $450 in 2004.
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  8. #8
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by StevenSurprenant View Post
    I thought that you might enjoy this. I'm not taking sides because I don't know.


    24/192 Music Downloads ...and why they make no sense:
    24/192 Music Downloads are Very Silly Indeed
    I scanned this document but will need to read it in detail. The argument that hypersonic frequencies causes more distortion than it removes is interesting but I don't know how relevant since no 192 kHz content would ever actually get to the amplifier, much less the speaker. Meanwhile I'll make these comments ...

    My own experience is with 24/88.2 and 24/96 files from HDTracks. They sound better than CD -- better resolution, especially in high frequencies and in loud passages having strings or brass, and a less strained sound in loud passages in general.

    I am deaf above 10 kHz at any volume that I would listen to, i.e. 85 dB or less. Whether it's the hypersonic that I'm not consciously hearing that what makes the hi-rez sound better, I don' know. In a few cases I've compared a hi-rez downloads with CD versions of the same recordings: the hi-rez versions sound better as described above. Possibly different masters are used for the hi-rez versions, however.

    In any case I will continue to buy hi-rez downloads and SACDs, (though I will need a better SACD player than I've got to realize the benefits of that format).

  9. #9
    Audio casualty StevenSurprenant's Avatar
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    Feanor...I am deaf above 10 kHz at any volume that I would listen to, i.e. 85 dB or less.
    This got me thinking. I knew I could hear 16kHz and I still can, but I hadn't plotted my hearing in many years. So I went to - Equal loudness contours and audiometry - Test your own hearing - which allows me to plot it. Of course the results are only relative to the volume I had used and my computer sits at ear level so it masks some of the frequencies. In addition, my sound card wasn't calibrated so that could skew the results.However, it's good enough for my purpose. BTW, I was using Grado SR60i headphones.

    Again here is the link for anyone that wants to test their own hearing.
    Equal loudness contours and audiometry - Test your own hearing

    I guess that I'm just like you since I usually listen at about 70dB give or take 10dB.

    Here are my results and it's not pretty!
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  10. #10
    Audio casualty StevenSurprenant's Avatar
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    The odd thing is that whenever I EQ I usually turn the bass down in the regions that the graph shows reduced hearing.

  11. #11
    M.P.S.E /AES/SMPTE member Sir Terrence the Terrible's Avatar
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    I am very familiar with this test and while I respect the outcome, I think it really misses the point of high resolution audio.

    The object of high resolution is to get the negative digital sonics(glassy, brittle, poor performance above 10khz with CD) out of the equation, and away from the music. 24/192khz does an excellent job of that with a good playback system.

    The second has to do with improved imaging. Humans can distinguish time delays when they involve the difference between their two ears of 15 microseconds or less. If you do the math, and you can see that while the sampling interval at 48 kHz is longer than 15 Ás, the sampling interval at 96 kHz is shorter. Therefore we prefer higher sampling rates because of time-domain resolution between the left- and right-ear signals is more accurately preserved at 96 kHz. It is even better improved at 192khz.

    Looking at the photo of the testing system, one can see just how close to the boundaries the speakers sit. This is surely to lead to reflections that cause comb filtering at the listening position. I see no acoustical treatment within the vicinity of the speakers to control or eliminate this. In this particular situation even moving your head a few inches could result in a -10 db dip, or +10 db boost in the frequency response you are going to hear. This is the effect of comb filtering, and it happens in varying degrees depending on how well the room is treated- it will always exist though. If a person gets up, and then sit back down, it is unlikely in this room they are going to hear exactly the same thing based on this because it is not likely the head will be in the same place each time. So while the speakers are stationary, the head would not be which affects what you will hear. If they didn't sit in the chair with their heads in a vice, I seriously doubt they would hear any changes in the program material. This would apply to each of the different systems and rooms the test was conducted in.

    There is also no frequency response plots of the speakers themselves, so how do we know the equipment itself is even capable of reproducing ultrasonic frequencies?

    Another thing that troubles me is different equipment in different rooms with different technical specification and acoustical properties yield different results.
    Last edited by Sir Terrence the Terrible; 10-04-2012 at 06:16 PM.
    Sir Terrence

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  12. #12
    Forum Regular hifitommy's Avatar
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    STT-bluebook cd=one listed in the orion blue book. heheheh!
    ...regards...tr

  13. #13
    M.P.S.E /AES/SMPTE member Sir Terrence the Terrible's Avatar
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    Quote Originally Posted by hifitommy View Post
    STT-bluebook cd=one listed in the orion blue book. heheheh!
    Okay, you got me! LOLOLOLOL
    Sir Terrence

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  14. #14
    M.P.S.E /AES/SMPTE member Sir Terrence the Terrible's Avatar
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    Quote Originally Posted by StevenSurprenant View Post
    The odd thing is that whenever I EQ I usually turn the bass down in the regions that the graph shows reduced hearing.
    Maybe because your system does not follow the hearing charts frequency response. Also this could be a matter of taste as well.

    I prefer a system that follows the chart in the bass region, but does the exact opposite in the high frequencies(has a slow roll off above 12khz).
    Sir Terrence

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  15. #15
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Sir Terrence the Terrible View Post
    I prefer a system that follows the chart in the bass region, but does the exact opposite in the high frequencies(has a slow roll off above 12khz).
    Diito. I abhor overtly *bright* sounding systems.

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