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Posted on April 21, 2015 at 11:29:06
wolfy
 Still trying to have a better understanding of digital audio. My ears tell me that higher resolution formats sound better. At the same time, I am a little mystified by the opposition being expressed at the movement beyond redbook CD.

I bumped into an article that was interesting and found a concept with which I could identify and was very well articulated (see below). Thanks Joe!:




Joe Baldwin, Virginia Beach, USA

With all do respect to the experienced engineers and sound technicians I must disagree. This disagreement is on a fundamental level and with the premise of the original article. The "facts" listed are not all of the facts and do not do justice to the bigger issue, (no matter how big a font the word "fact" is presented). If you stay with me a bit, I think that you might agree.

I have friends that claim to be audiophiles, but are really techno-weenies with too much money, and I have other friends who can actually discern differences in audio component in double blind tests simply because they have extraordinary hearing as well as technical knowledge. To the latter group, CD's (Redbook 44.1KHz/16bit) are clearly not as true a medium as high quality vinyl. There is a good technical reason for it. It appears to be resolution, encoding/decoding errors, and encoding/decoding standards errors.

Repairing the standards errors, advent of higher quality A/D D/A converters (no matter the resolution) has gone a long way to improve the digital medium.

With respect to resolution: it appears that many recording professionals have warmed up to an increase is resolution. Lets be specific here: the vertical axis representing amplitude has been steadily increasing from 8 to 16 then to 24 bits, and now some software has standardized on 32 bit internal processing. The horizontal axis representing time has increased (recently) from 44.1 samples per second to 48, then 96, and on up to 192.

It appears from the current discussion that increasing resolution in the vertical axis is assumed to be G.O.O.D while increasing resolution in the horizontal direction is assumed to be B.A.D. The only real cogent reason (other than misunderstanding) for this is that increased bit depth is much easier to store and process with current computer technology than is sample rate. High sample rates mean costlier computers and M.U.C.H bigger hard drives, and S.L.O.W software.

So why is the horizontal axis resolution increase not invited to the party and the vertical axis resolution embraced? Good question. Lets table that question and get to the F.A.C.T.S. Here is a table of Horizontal Resolution:

48 KHz sample rate Table

Audio Frequency | Number of Samples/wave

------------------------------------------------

24 KHz | 2 samples/wave

12 KHz | 4 samples/wave

6 KHz | 8 samples/wave

3 KHz | 16 samples/wave

1500 Hz | 32 samples/wave

750 Hz | 64 samples/wave

.... and so on

Kind of surprising F.A.C.T.S when lower frequencies are considered, isn't it? Therefore, this is not just a discussion about super high frequencies, this is ultimately a discussion of Horizontal axis waveform resolution.

Now for Vertical resolution:

Bit-Depth Table

# Bits | Discrete Amplitude steps

----------------------------------------

8 | 256 steps

16 | 65,536 steps

24 | 16,777,216 steps

OK, so far we have 16 Million steps in the vertical direction vs 'way not many' in the horizontal.

Even the most entrenched Horizontal-High-Resolution-phobic among us will observe that even in substantially mid audio frequencies such as 1500 Hz while there is over 16 Mega-Steps in the Vertical there are only 32 Steps in the horizontal.

Can your ears hear it? Yep. Do we really need HD TV at 1080 Horizontal scan lines when we have Super Video at around 400 scan lines, or 16 Million colors? Yep. In fact I would argue that if the technology could support it, 192 KHz sample rate is not nearly enough. Crazy? Well consider this factiod: at 192 KHz sample rate we would be up to a whopping 256 samples for a 750 Hz wave. Dude, that is like almost 8 bits rotated to the Horizontal axis for a substantially well-within-the-hearing-range of non-audiophiles and old people :).

Finally, check out this (very daunting) analysis of "Nyquist Theorem's Consequences":

http://www.digital-recordings.com/publ/pubneq.html#theorem

It appears to confirm my 3rd grade math-tool analysis above (as well as my ears), that the trouble with adhering to the Nyquist Theorem in a pedantic manner results is more errors as the frequency increases (starting at relatively mid-range frequencies). Said simpler: as the frequency goes up so do the errors and thus distortion as a direct result of decreased resolution per wave.

My conclusion is that given what my hearing tells me, the low resolution of samples/waves, and the Nyquist Consequences analysis, current sample rates per wave must be improved upon in order to faithfully capture mid-high frequencies that are demanded by audiophiles and others. Personally I think, when we get to the point of having on the order of >= 65,000 (or even 1/10 that number) samples per wave at 15Hz-10KHz-audio, then we can start a reasonable debate about what is 'too much' resolution in the Horizontal direction. Until then, striving to increase the Horizontal resolution while not overburdening a CPU (or the pocket book) is an exceedingly worthwhile endeavor for the technical recording artist.
Wednesday January 18, 2006

 

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Well...all that analysis is a bit too technical for me, but..., posted on April 21, 2015 at 16:06:37
jeffreybehr
Audiophile

Posts: 5719
Location: Phoenix, Arizona
Joined: December 10, 2004
Contributor
  Since: December 13, 2004
 ...I know that what I hear as the BEST-sounding, most-transparent* recordings, ever, from my system are always SACDs mastered in DSD. Never have I observed with my ears HIGH transparency to discover the recording was mastered in 44.1MHz PCM of any bit depth. I really enjoy the spaciousness and concerthall naturalness of BIS recordings, but when I buy a BIS SACD and listen and am NOT impressed with its (lack of) transparency, it's always mastered in 44.1KHz PCM. I wonder why they do that?

The absolutely best, most-transparent Classical-music recording I've ever heard is a TELARC, titled Grieg/Dvorak/Elgar, number SACD-60623, now discontinued I believe. The Rotterdam Chamber Orchestra plays the Holberg Suite, the Serenade for Strings o. 22, and Serenade for Strings o. 20, respectively. Polyhymnia recorded it in DSD. I and a golden-eared friend, independent of my observations find the Elgar to sound best, and when I listen to that and when the moon, stars, other planets, etc., are all aligned, it really sounds as if I'm in the hall, sitting on a stepladder a few feet behind the conductor, with those 31 musicians playing just for me. The jillion dollars I've spent on my music-reproduction system over the decades is all worth it then.

* 'Transparency' describes the sense of there being NOTHING but 10 to 20 feet of air between me and the musicians.

 

RE: horizontal resolution, posted on April 21, 2015 at 17:29:21
John Elison
Audiophile

Posts: 23900
Location: Central Kentucky
Joined: December 20, 2000
Contributor
  Since: January 29, 2004
 Horizontal resolution? I guess that's why they invented DSD. ;-)

 

RE: horizontal resolution, posted on April 21, 2015 at 17:43:00
fantja
Audiophile

Posts: 15524
Location: Alabama
Joined: September 11, 2010
 Thanks! for sharing- wolfy. Really interesting info.

 

Oh no!!! Already a competing new format for MQA!!!!, posted on April 22, 2015 at 00:35:00
stehno
Manufacturer

Posts: 739
Location: Oregon
Joined: November 8, 2001
 Only the horizontal format seems to make more sense than what the seemingly hyped MQA format intends to do.

There's only one problem with the theoretical horizontal resolution format as well as with the MQA and all other already established high-resolution formats.

They are all barking up the wrong technology tree. That is, if one is seeking anything more than relatively minor performance improvements.

What nobody seems get or at least admit to, is that listening to even the most well-engineered high-rez recording on a well-thought-out $1million SOTA-level playback system, the listener is not audibly hearing anything more than roughly the equivalent music info capacity of a well-engineered MP3 recording.

That's the intellectual truth of the matter.

The cause of this catastrophic problem (to use Robert Harley's words) is not inferior resolution. Rather it's a grotesque amount of superior and universal distortions that utterly destroy or cripple a component's precision and accuracy so that the noise floor is raised so high as to render much of the music embedded in the recording inaudible below the much raised noise floor and therefore remain inaudible.

I would attest that perhaps every last reasonably thought-out playback system is reading and processing roughly 99.999% of all the bits embedded in a given recording. No better or worse than downloading a 100MB flac file or burning that same flac file to your $40 CD burner that came with your computer.

All the detail in the world is being read and processed, only just like a severely blurred photo of a beautiful red Ferrari where the noise floor of the photo is so high, you can barely even tell it's a Ferrari. Is all the detail of the Ferrari stored in the photo? I say yes. But much of the signal is so distorted, it remains invisible. A performance-limiting governor if you will, that plagues every last playback system. This is why even well-thought-out playback systems all sound more alike than they do different and not one of them comes even remotely close to the absolute sound aka the live performance.

Bear in mind that the most severe distortions are not even audible per se. These are inaudible distortions that quietly go about their business of catapulting a given playback system's noise floor to very high levels. And it's not just low level detail as many speculate. The harm is induced pretty much equally between low and high level detail.

And just like with a 3.5MP camera or a 13MP camera, the problem with the blurred photo is regardless of the camera's resolution capability or the number of pixels stored per photo graph. An unblurred photo of a beautiful red Ferrari taken with a 1.5MP camera is far more beautiful than a blurred photo of the same Ferrari taken with a 16MP camera.

And just like the camera analogy, it's not the number of music info bits that remain inaudible, it's the percentage of music info bits that remain inaudible due to the much raised noise floor.

This is not hypothesis, this is fact and is demonstrable. But when "scientists" and the science-minded are already halfway up the wrong technology tree, it's pert near impossible to call them down until the entire industry has been forced to buy into it at great expense.

Only for many to wake up 5 or 10 years later realizing they've been doing cartwheels over small incremental improvements when the industry had them convinced the advancement would be life changing.

This is why a well-engineered MP3 recording played back on a SOTA-level system theoretically isolated from the harm induced by such universal distortions should sound at least if not far more naturally musical than a well-engineered 24-bit / 192 kHz high-rez recording on the same SOTA-level system fully susceptible and affected by these universal distortions.

It's not the resolution or format.

 

The analysis is old hat - obsolete, posted on April 22, 2015 at 06:59:25
Fitzcaraldo215
Audiophile

Posts: 1120
Location: Philadelphia
Joined: September 7, 2008
 One of the key points about higher sampling rates/bit depths "overtaxing" processors is hopelessly out of date. There is no such problem today. Some recording companies routinely use 384k or higher PCM sampling or double DSD sampling, or even higher than those. Home equipment for playback also exists. My DAC handles 384k/quadruple DSD with no problems from my PC.

My PC routinely plays 6 or 8 channel recordings from my NAS at 192k or from DSD converted to 176k, while simultaneously performing DSP processing for bass management and complex Dirac Live room EQ. It does that without any degradation whatsoever even while independent processing tasks are running simultaneously. The PC itself is a stock Windows PC using an I7 processor, which cost under $1,000.

Yes, there are rapidly dimishing returns and vanishingly small sonic advantages from ever higher sampling rates/bit depths. But, hi rez sounds noticeably better than standard 44k/16. Even 48k/24 does. One main advantage is greater freedom from time domain artifacts in the reconstruction filter for PCM as it is pushed up further in frequency into inaudibility, and DSD also avoids that by its very nature. Added bit depth audibly improves low level detail, such as reverberation tails.

So, one can go crazy with resolution numbers. But, single DSD or 88k or 96k PCM are very worthwhile over 44/16.



 

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