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  1. #111
    Robin Bowes
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    DAC Resolution Test and Don't EVERuse Digital Volume Control

    On 01/05/10 03:02, mswlogo wrote:
    >
    > Robin Bowes;542141 Wrote:
    >> On 01/05/10 02:11, mswlogo wrote:
    >>>
    >>> Robin Bowes;542127 Wrote:
    >>>> On 30/04/10 20:28, mswlogo wrote:
    >>>>> ... the pristine ones always take full advantage of all the
    >>>>> dynamic range and have just an itty bit of clipping.
    >>>>
    >>>> So, you think that the best sounding CDs have digital clipping???
    >>>>
    >>>> I think that speaks volumes.
    >>>>
    >>>> R.
    >>>
    >>> Absolutely. If you don't understand that it does speak volumes.

    >>
    >> .... or you're possibly using the term incorrectly.
    >>
    >> Would you care to elucidate further what you mean by "just an itty bit
    >> of clipping"?
    >>
    >> R.

    >
    > Sorry I don't have much time right now. But exactlty that. An itty bit
    > (say 10 samples by 1dB is sign a meticulous mixing job. If I see 3db or
    > 6db of headroom for no reason that's just lazy. Does a song have to have
    > a be clipping to be a good mix no. But most do. It's better to clip the
    > fringes than to compress or attentuate just avoid clipping a few
    > samples.


    You have just spent rather a long time doing some bizarre test which
    advises folk never to use digital attenuation because of the damage it
    causes to the signal, and now you're suggesting that cutting off whole
    samples by 1dB is fine???

    This is truly priceless!! You really have no understanding of either
    analogue or digital audio engineering, do you?

    R.

  2. #112
    Senior Member mswlogo's Avatar
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    Quote Originally Posted by Robin Bowes View Post
    On 01/05/10 03:02, mswlogo wrote:
    >
    > Robin Bowes;542141 Wrote:
    >> On 01/05/10 02:11, mswlogo wrote:
    >>>
    >>> Robin Bowes;542127 Wrote:
    >>>> On 30/04/10 20:28, mswlogo wrote:
    >>>>> ... the pristine ones always take full advantage of all the
    >>>>> dynamic range and have just an itty bit of clipping.
    >>>>
    >>>> So, you think that the best sounding CDs have digital clipping???
    >>>>
    >>>> I think that speaks volumes.
    >>>>
    >>>> R.
    >>>
    >>> Absolutely. If you don't understand that it does speak volumes.

    >>
    >> .... or you're possibly using the term incorrectly.
    >>
    >> Would you care to elucidate further what you mean by "just an itty bit
    >> of clipping"?
    >>
    >> R.

    >
    > Sorry I don't have much time right now. But exactlty that. An itty bit
    > (say 10 samples by 1dB is sign a meticulous mixing job. If I see 3db or
    > 6db of headroom for no reason that's just lazy. Does a song have to have
    > a be clipping to be a good mix no. But most do. It's better to clip the
    > fringes than to compress or attentuate just avoid clipping a few
    > samples.


    You have just spent rather a long time doing some bizarre test which
    advises folk never to use digital attenuation because of the damage it
    causes to the signal, and now you're suggesting that cutting off whole
    samples by 1dB is fine???

    This is truly priceless!! You really have no understanding of either
    analogue or digital audio engineering, do you?

    R.
    I work with analog and digital signals at data rates that would make your head spin. I work on mass spectrometers. What do you do?

    Replies like yours are priceless.

    I'm sorry that the clipping I'm referring to is beyond your grasp.

    Throwing bits off the bottom effects every sample negatively. Throwing bits off the top of a few samples won't effect audio negatively.

    You have factor TIME into this.
    Last edited by mswlogo; 2010-04-30 at 21:34.
    Transporter/DuetController > SPDIF > Meridian G68 > DSP6000, DSP5500HC, DSP5000

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  3. #113
    Senior Member pfarrell's Avatar
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    DAC Resolution Test and Don't EVERuse Digital Volume Control

    mswlogo wrote:
    > I work with analog and digital signals at data rates that would make
    > your head spin.


    Specifics please?

    > Replies like yours are priceless.
    >
    > I'm sorry that the clipping I'm referring to is beyond your grasp.


    1/10


    --
    Pat Farrell
    http://www.pfarrell.com/


  4. #114
    Senior Member mswlogo's Avatar
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    Quote Originally Posted by pfarrell View Post
    mswlogo wrote:
    > I work with analog and digital signals at data rates that would make
    > your head spin.


    Specifics please?



    > Replies like yours are priceless.
    >
    > I'm sorry that the clipping I'm referring to is beyond your grasp.


    1/10

    --
    Pat Farrell
    http://www.pfarrell.com/
    I write software for Mass Spectrometers. We sample at 4Ghz. We determine the speed at which IONS fly through a vacuum in order to determine their Mass.

    We have dozens of DACs and ADCs and I understand them quite well. We oversample from 2 - 2 million times. One ADC we use cost around $23K each (that's discounted in volume ).

    I also have written a children’s programming language and digital simulator I publish for free and used in many schools and colleges. Hence the name mswlogo.

    I also run the Meridian forum for 10 years. And have invested about $40K in Meridian audio. And I want every ounce of performance out of it.

    Is that specific enough for you? Do you need my full resume?

    I would provide you some real examples with wave forms to explain how this works but you folks are so close minded I think I'd be wasting my time.

    I gave a fairly good example.

    Here it is again slightly changed.

    Think of a photo that is 24 x 24 inches.

    But your frame is 16x16.

    Where is the best place to place the frame?

    The "important" content is in the middle !!

    Do you place it on the upper right corner?
    So you won't "Clip" the upper right.
    Oh my that would be terrible to clip white sky with a tiny bug in it you can't see from 2 feet away. Let the bug clip so you can get some nice grass on the bottom. It adds to the WHOLE picture.

    You place it some where in the middle.

    You could "compress" the photo to fit but that has problems too. But a little compression is ok.

    It's a balance !!!

    Don't ignore the bottom (even if it's low level).
    Don't be paranoid about the top either (if it does not persist long enough you won't hear it if you clip it out).

    And don't F'k with the frame once it's been placed by a good framer.
    Last edited by mswlogo; 2010-04-30 at 22:19.
    Transporter/DuetController > SPDIF > Meridian G68 > DSP6000, DSP5500HC, DSP5000

    "It's the speakers and room stupid".

    My Transporter Setup
    Hitch Hikers Guide to Meridian

  5. #115
    Senior Member pfarrell's Avatar
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    DAC Resolution Test and Don't EVERuse Digital Volume Control

    mswlogo wrote:
    > We determine the speed at which IONS fly through a vaccum in order to
    > determine their Mass.


    I did that in high school physics class, over 40 years ago.

    You are still a troll, and your score is no higher than
    1/10
    on the SeanTrollScale

    --
    Pat Farrell
    http://www.pfarrell.com/


  6. #116
    Senior Member mswlogo's Avatar
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    Quote Originally Posted by pfarrell View Post
    mswlogo wrote:
    > We determine the speed at which IONS fly through a vaccum in order to
    > determine their Mass.


    I did that in high school physics class, over 40 years ago.

    You are still a troll, and your score is no higher than
    1/10
    on the SeanTrollScale

    --
    Pat Farrell
    http://www.pfarrell.com/
    It's such a shame folks like you are allowed trash a discussion like this.

    Talk about being a troll.

    I'm done you win. It really is a shame.
    Last edited by mswlogo; 2010-04-30 at 22:53.
    Transporter/DuetController > SPDIF > Meridian G68 > DSP6000, DSP5500HC, DSP5000

    "It's the speakers and room stupid".

    My Transporter Setup
    Hitch Hikers Guide to Meridian

  7. #117
    Senior Member Themis's Avatar
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    I follow this with interest, as I know little on the subject.
    I hope you folks will stop being rude to each other and won't let your passion spoil the debate...
    SBT - North Star dac 192 - Croft 25Pre and Series 7 power - Sonus Faber Grand Piano Domus

  8. #118
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    I've studied the Meridian papers and the 518 manual.
    In 1995, the 518 was addressing certain very real problems that to some extent have now been addressed in other ways.
    Specifically, their major concern is optimising the transfer function across boundaries where bit-depth changes and preserving/improving the "subjective dynamic range" (their term) across boundaries of equal bit-depth.

    Where DSP functions such as gain control act on digital signals they introduce errors (noise) in the LSB's. For a signal well below full-scale (say 30dB - a very quiet section in a piece of classical music) the MSB carrying musical signal is only a few bits away from the noise floor. Errors introduced in the LSB will be more audible here. So they advocate, amongst other things, raising the gain of a track so that it peaks at full scale (or even occasionally clips) in order to maximise the gap between the LSB errors and the music.

    This is perfectly logical, not voodoo and indeed what I and 99% of people who have ever mixed/mastered anything would do - although there are many different ways of doing it.

    For dealing with very brief clippping on individual tracks for instance, I would manually edit the handful of samples involved to reduce their level to full scale - effectively a manual compression operation, albeit rather time consuming and fiddly. In practice this would enable a master mix at near full-scale peaking without having to leave 3-6dB headroom across the track as a whole. One could also use soft-clip digital (or analogue) limiters to achieve the same thing - this can be abused (loudness wars).


    Anyway, all of the above is very pertinent to what happens prior to dithering down to 16-bit for CD manufacture.

    Bear in mind that in 1995 full-chain 24/96 recording was not available... and that 20-bit DACs were not common in domestic settings.

    The term "subjective dynamic range" is important... they are talking about keeping the dsp-generated noise in the LSB as far away as possible away from the signal. So, it's really a discussion about SNR.

    I think this is where we are talking at cross-purposes. AUDIBLE dynamic range is the difference between the max/min SPL actually produced by your speakers (excluding the noise floor post-DAC) - i.e. what you hear! A DAC signal has a fixed, finite theoretical "dynamic range" determined by the number of bits (96/144). In practice, this is limited by noise in the LSB's (from a variety of causes) and the real-world 20-bit limitation of audio ADC's.

    Using Meridians own graph, the scope of human hearing is 19-bits.
    This is why a 20-bit replay chain can outperform a 16-bit one with 20-bit source material. However because of auditory masking, the EFFECTIVE (ie the difference between the loudest and softest sounds you can actually discern at the same time) "subjective dynamic range" is more like 60-75dB (10-13 bits). This is why good FM radio, analogue master tape and even vinyl can sound great!

    The LSB errors that Meridian are (rightly) concerned with are MUCH less important with a 24/20 bit chain - as they are at/below the scope of human hearing. Also, the MSB-LSB gap is greater at all times, even on quieter passages so the LSB noise remains further from the music.

    This is why many people love tracking at 24-bit - you can run with (say) 18dB of headroom for the occasional peaks without needing compression and not worry too much about the noise floor - you simply wouldn't do that with 16-bit - you'd run as near full scale as you dare and use a hard-knee compressor for safety - but then the compression is irreversible and the original dynamics have been permanently altered...



    So returning to the original topic of this thread, what level of digital attenuation in an SD device is deleterious to the sound?

    The OP's opinion is "any digital attenuation is bad" (but presumably analogue attenuation POST-DAC is fine?)

    My position is that both analogue and (properly designed 24-bit or greater) digital attenuation are audibly indistinguishable on decent downstream equipment... until you reach the point where the EFFECTIVE (ie resolvable) subjective dynamic range is compromised. IME this doesn't begin to happen until you get down to below 13 "live bits" on 16-bit source material (19 on 24-bit material)

    So, incorrect gain staging can induce this. Stay below 18dB of digital 24-bit attenuation on 16-bit material, use a 24/20 bit DAC and all should be fine...

    On 24-bit material, up to 30dB of 24-bit digital attenutaion should be fine.

    And remember, once something is so quiet you can't hear it, it doesn't matter HOW it go to be that quiet...

    For the last time... if you can't hear a marching band mixed into Brahms Lullaby in the bottom 3-bits of a 16-bit full-scale peak recording, you can't hear the bottom 3-bits of the Lullaby either!!!!

    If ANYONE can pass this test (or indeed if anyone can tell me how to cheat the test - and there are enough clues in this post to answer that conundrum) we can talk further..


    By the way, I was looking at some very quiet passages on 16-bit classical stuff and the lowest level I could find was 40dB (7 bits)... and that was right at the very beginning of a quiet track. So even losing 3 bits is not fatal to the music... although for that brief period the SNR will only be 24dB or so...

    Does it sound bad - no, just quieter.
    Can you hear the worsened SNR? - not at normal listening volumes. If you boost the post-DAC gain to speaker-threatening levels and press your ear to the tweeter... yes. I wouldn't advise this.

    Can any of this be measured? - yes. A final point to all of those worried about "loss of resolution", which I take to mean they think that bits of music signal are being damaged... use ADM and prove it to yourself. How far do you have to attenuate before the null difference is not just white noise?

    That's your homework... now play nicely.
    You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal...
    Touch(wired/W7)+Teddy Pardo PSU - Audiolense 3.3/2.0+INGUZ DRC - MF M1 DAC - Linn 5103 - full Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Pekin Tuner, Townsend Supertweeters,VdH Toslink,Kimber 8TC Speaker & Chord Signature Plus Interconnect cables
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  9. #119
    Senior Member Themis's Avatar
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    Quote Originally Posted by Phil Leigh View Post
    For the last time... if you can't hear a marching band mixed into Brahms Lullaby in the bottom 3-bits of a 16-bit full-scale peak recording, you can't hear the bottom 3-bits of the Lullaby either!!!!
    I'm not sure about that, Phil.

    The marching band is uncorrelated to the Brahms, so it is treated as background noise.
    The fact that you can't hear it, doesn't necessarily mean that if you had 3 bits of correlated signal it wouldn't be noticeable.
    Does it ?
    SBT - North Star dac 192 - Croft 25Pre and Series 7 power - Sonus Faber Grand Piano Domus

  10. #120
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    Quote Originally Posted by Themis View Post
    I'm not sure about that, Phil.

    The marching band is uncorrelated to the Brahms, so it is treated as background noise.
    The fact that you can't hear it, doesn't necessarily mean that if you had 3 bits of correlated signal it wouldn't be noticeable.
    Does it ?
    Themis - Try it for yourself and see what you think. In one version the bottom 3 bits are the bottom 3 (100% correlated) bits of the lullaby, in the other they have been replaced by something else (in this case a marching band mixed with the lullaby, could have been anything uncorrelated really)...

    So the bottom 3 bits in that version are a mixture of correlated and uncorrelated information

    Still can't hear those 3 bits...
    You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal...
    Touch(wired/W7)+Teddy Pardo PSU - Audiolense 3.3/2.0+INGUZ DRC - MF M1 DAC - Linn 5103 - full Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Pekin Tuner, Townsend Supertweeters,VdH Toslink,Kimber 8TC Speaker & Chord Signature Plus Interconnect cables
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