Which is more accurate: digital or vinyl?

Thanks, Al :-)

Vbr,
Sam

"Had this problem been addressed properly from the get-go, I suspect that about 90% of the D vs A debate in the last 30 years simply would not have occurred. "

Would would constitute addressing it properly?

I do not hear the brightness you refer to categorically associated with CD or digital in most of my CDs compared to vinyl or other references I have heard. So my ears tell me that there is no redbook plague associated with the format that makes it incompatible to human ears (which I understand are not ruler flat in response, so what, we hear everything the same be it coming out of a stereo or real). I do understand though that it can be a common plague with many CD rigs and has been in mine as well in the past. But I do not understand how the format itself or even being digital precludes this.

I listen to CDs with Class D amps that use negative feedback and still have no issues I can go as loud as I want with my rig with little to no fatigue or brightness. So my experience does not correspond to what you are saying.

I will not question that digital and SS amps with negative feedback in practice have been more plagued by this. Only that it is not inherent to teh technologies categorically, end of story. It can be done extremely well in either format. I do suspect though that R2R is in another league though, for whatever that is worth practically to most.

The how we actually hear stuff is fine but I don't see how what you say applies to analog only. Both analog and digital are shooting for similar results as best I can tell and I have heard both do quite well despite the inherent limitations of each.

Mapman, not trying to change the subject, just pointing out that in the development of Redbook, human perceptual issues were largely ignored. To give a little more depth, we humans tend to not make things perfect, try as we might. In the case of digital, there tend to be in-harmonic distortions that are related to the scan frequency rather than harmonically related to the signal like we have in analog systems.

The problem is that the human ear takes higher-ordered content like this and interprets it as brightness. (this significance of this is that when you measure the digital system on the bench, it will appear to be ruler-flat in frequency response- it is our human perceptual rules that assign the brightness.) Had this problem been addressed properly from the get-go, I suspect that about 90% of the D vs A debate in the last 30 years simply would not have occurred.

This is an issue that has nothing to do with the misapplication of Nyquist, BTW. Now I have been accused of many things over the years, bias being one of them, but in this matter of digital, all I can say is I would really like it to work! I would much prefer to not have to provide space for all the vinyl I own, to fit it on a RAID array would be awesome! But my system is too revealing and the failings of digital are very obvious on it. Mind you, I've done no 'tuning' or 'voicing' or any particular treatments to somehow favor analog over digital. And I can put on a Redbook CD and enjoy it, but even my girlfriend who has no interest in audio at all comments on the obvious improvement that vinyl demonstrates over digital. I think too many people have not been exposed to decent analog playback (for example, improper setup of the equalization circuits in a phono preamp can exacerbate ticks and pops) and so the debate rages.

11-08-11: Almarg
The difference in db between the maximum possible value as represented digitally (65,535 as expressed in decimal form) and one "level" less than that ... is:

20log(65535/65534) = 0.000132 db

A slight correction to this statement in my earlier post. Since a sign bit is involved, which defines + or -, the range of possible values expressed in decimal form is -32,768 to + 31,767. So the quoted equation should be:

20log(31767/31766) = 0.000273 db

Regards,
-- Al

Hi Sam,

This Wikipedia article appears to address your questions much more knowledgeably than I could. Some excerpts:

Because of the nature of sigma-delta converters, one cannot make a direct comparison between DSD and PCM. An approximation is possible, though, and would place DSD in some aspects comparable to a PCM format that has a bit depth of 20 bits and a sampling frequency of 96 kHz.[3] PCM sampled at 24 bits provides a (theoretical) additional 24 dB of dynamic range....

DSD's dynamic range decreases quickly at frequencies over 20 kHz due to the use of strong noise shaping techniques which push the noise out of the audio band resulting in a rising noise floor just above 20 kHz. PCM's dynamic range, on the other hand, is the same at all frequencies. (Some high-end SACD players employ an optional low-pass filter set at 30 kHz for compatibility and safety reasons, suitable for situations where amplifiers or loudspeakers cannot deliver an undistorted output if noise above 30 kHz is present in the signal)....

The Korg MR-1000 1-bit digital recorder samples at 5.6 MHz, twice the SACD rate. It's also referred to as DSD128 because of the sample rate 128x that of CD....

There has been much controversy between proponents of DSD and PCM over which encoding system is superior.

Best regards,
-- Al

Al, Ralph,

How about DSD?

In a direct transfer --no remixing or remastering-- of an AAA, 1/2", half-track, 15/30 ips reel master...which product/process, Redbook CD or DSD64, would yield the nearest fidelity to the source/master tape?

Would the answer change if the evaluation were made in a 64-bit DAC and DSD128 environment?

Thanks for your consideration,

Sam

24/192 would be a safe bet i would say, an insurance policy perhaps more than anything, with a price.
16/44 is pretty good...good enough for most but does cut it somewhat close at least for younger better ears and technology today is capable of better.

my dac cannot do 24/192 but can handle some lesser high rez formats. i need to give hd tracks a try.

16 bits specifies 65,536 levels, approximately 0.00146 decibel per level.

Actually it shouldn't be looked at that way, because the CD medium uses linear encoding, while the db scale is logarithmic.

For example, the difference in db between the maximum possible value as represented digitally (65,535 as expressed in decimal form) and one "level" less than that (perhaps more properly expressed as one LSB increment less than that, referring to the voltage increment corresponding to the Least Significant Bit) is:

20log(65535/65534) = 0.000132 db

In contrast, the difference in db between a value of 1 LSB increment above zero and a value of 2 LSB increments above zero is:

20log(2/1) = 6.02 db.

So the number of "db per level" varies very widely depending on the specific levels that are being considered.

What's the smallest level change the human ear is capable of discerning?

What matters in this context is not the perception of changes in level, but our ability to perceive, among other things, differences in the RELATIVE amplitudes of the harmonics and other spectral components that collectively constitute a note. Our hearing mechanisms are far more sensitive to those kinds of differences, which affect timbre for one thing, than they are to simple volume changes.

Speaking more generally, many of the recent posts in this thread have been excellent, IMO. Too many to cite individually. Ralph's point about analog hiss being much less objectionable than its digital counterpart (quantization noise resulting from the limited number of bits per sample), is a very good one of course. It should be mentioned, though, that careful application of dither in the digital recording process can go a long way toward minimizing that issue. And along the lines of Ralph's comment, careful "normalization" of volume levels during the recording process can minimize or eliminate the extent to which bits are sacrificed as a result of, for instance, overly conservative headroom allowances.

It should also be pointed out that the 110db or so of dynamic range that a high quality analog tape machine may be able to provide is considerably greater than what can be put onto and retrieved from vinyl, as well as being more than what can be supported by most listening environments, and more than what is required by most music.

A bottom-line point, IMO:

Although I haven't yet gotten into hi rez, my suspicion, given how good SOME redbook cd's can sound, is that 24/192, if well implemented in both the recording and playback parts of the chain, should be good enough to deliver digital's full potential, in terms of perceived accuracy (which is the subject of the thread).

On the other hand, the subjective preferability of that potential vs. vinyl at its best is another question altogether, about which opinions will obviously differ.

Best regards,
-- Al

Say what dudes?

16 bits specifies 65,536 levels, approximately 0.00146 decibel per level. I've read conflicting accounts. What's the smallest level change the human ear is capable of discerning?

Assuming fixed dynamic range, resolution results from a combo of the # bits used to quantify each digital signal amplitude value captured and how frequently (the frequency with which) the signal is quantified.

So a finer definition of amplitude contributes to higher POTENTIAL or maximum real resolution assuming the maximum dynamic range stays the same.

How much resolution is actually achieved is a different story that depends on how well executed the implementation is but more bits used will enable more resolution, all else held constant.

Alternately, increasing the dynamic range and quantifying using the same # of bits will result in lower potential or maximum resolution because the same # of possible digital values must now be used to represent a larger variation in amplitude.

So yes, theoretically smoother amplitude levels can occur. Whether these are audible or not still depends on other factors and makes things more challenging to model accurately.

"sample" is really not an accurate term to apply in the digital signal processing scenarios because a sample is a statistical concept as well and in stats means a small but representative subset of a population.

Whereas with digital audio and video the intent is to quantify the entire signal as completely as possible, not 'sample" it, which is different.

Maybe this is part of why there are so many misconceptions about digital audio?

How does a finer definition of amplitude equate to resolution? Would smoother amplitude levels be audible?

"Bit depth describes the dynamic range"

That is true for any particular application or format spec, like CD redbook, but not in general.

More bits can mean more accuracy and/or more dynamic range. So if the specified maximum dynamic range stays the same, more bits will mean finer resolution per sample in terms of representing amplitude more accurately.

64 bits? Bit depth describes the dynamic range, 16 bits=96 dB, 20 bits=120 dB, 24 bit=144 dB. The later could record a jet taking off and a pin drop without changing the gain. That's more than enough for the most dynamic music with headroom to spare.

I might be willing to assert that quality control with good modern digital formats is miles ahead of any ancient analog technology, regardless of the inherent advantages otherwise.

Assuming this, that would indicate that digital in practice rather than in theory is inherently more accurate and precise.

Atmasphere,

Are you trying to change the subject?

The how we actually hear stuff is fine but I don't see how what you say applies to analog only. Both analog and digital are shooting for similar results as best I can tell and I have heard both do quite well despite the inherent limitations of each.

I suspect you may have some bias in your viewpoints regarding digital given your background and interests.

Nothing wrong with that, we all believe what we believe and are all biased in some way.

I like the idea of making comparisons in the common voltage domain and trying to quantify things there if possible? Not sure to what extent it is but I think it makes sense. Then we could talk in quantitative terms about what is really going on. That's the only way to ever really know.

I am on board with all the how we hear stuff, but I do not think good solutions in this regard is limited to any single paradigm or technology necessarily, though the challenges with each is clearly different.

Mapman, suggests another good point. With vinyl there seems to be much more dependency on the accuracy of many more mechanical stages from beginning to end (user), and how does that actually turn out in overall real use?
In the end, even with the issues of availability, convenience, portability, record-ability and durability aside, it may come down to which format comes closer to the bulls eye, more often? How that is judged will perhaps be very personal. Some scoring more isolated cases of nearness to perfection higher, others scoring consistency higher. Even within those parameters, the scoring might vary, e.g., with some dismissing different levels of extraneous noise to different extents, and other penalizing extraneous noise to different extents. And, the same kind of scoring could be applied to what ever other various criterion different individuals prioritize differently.
At the risk of being redundant, I have yet to be convinced that one format consistently outperforms the other. With that said, I choose to consider those issues I previously suggested be put aside, availability, convenience, portability, record-ability, and durability and add one other, value(!) when I choose a format.
Except for those with an existing compilation of a particular format, or those rare few, for which cost is not even a consideration, I would offer that good digital can be quite a bit less expensive than good analog, and the extra funds might ultimately be better spent on music, rooms, DSP, speakers, etc..

Al is right, my 64-bit idea is mostly fantasy :)

Here is the problem, in a nutshell, the problem that seems to plague **all** aspects of audio:

There are the Rules of Human Hearing/Perception, and there are the specs on paper. They are not the same- the specs on paper for the most part don't give a damn about human hearing rules.

Now I have gone off about this a lot in the Amps/Preamps forum and won't belabor those issues as examples. Instead, let's look at how the ear treats noise, specifically analog hiss: Normally, our ears employ a masking feature, IOW the presence of a louder sound will block the presence of a quieter sound to our perception. Hiss is the one exception to that rule. I suspect its an evolutionary thing myself- the idea that hiss is similar to the effects of wind in the environment is not that far-fetched to me.... Anyway, we have the ability to hear about **20 db** into the noise floor of an analog system.

(if the noise floor is not composed of hiss, but instead is harmonic or in-harmonic noise related to the signal, our ears will not penetrate that, and so that type of noise floor will define the limit of low level detail that can be retrieved.)

With modern tape, 1/2" format, this means that you have the possibility of a 110 db dynamic range, if you include the range above 0 VU, a range that digital does not have.

This simple fact explains why an analog system of rather modest noise specs can have more low level detail than the best digital systems -*even though it appears to be noisier*. Add to that the fact that digital systems use less bits to resolve lower level signals (IOW, they have loose resolution as signal level decreases, which is why the normalization process is so important in the production of a CD) and you have a great part of why digital systems **as they are** can't keep up with analog.

IOW, part of it has to do with how we hear, and for the most part digital audio has ignored that, which has been a common problem with audio in general in the last 45 years or so :( Put another way, analog just happens to work better with the way our ears work.

Mapman, That is an excellent question and rationale in last para.
We have good arguments from both Digital(Red book and beyond) and Analog (Vinyl). Lot of discussion automatically assumes Analog to be continous (theoretically) but like Mapman implies what is the practicality?

Has any one plotted signal pick up of say a same sinusoidal test tone recorded both on Vinyl(played back on most accurate set up or even a cutter) and 16/44.1 to compare continuity of these curves?

"Quantization of a 2 volt full-scale range into 64 bits
would mean that the least significant bit corresponds to
about 0.0000000000000000001 volts."

I wonder what the comparative resolution of vinyl in volts
can practically be?

How about compared to 16 bits even?

I doubt there are many if any lps constructed perfectly
enough for
it to matter.

Also since record playback involves movement of a stylus
that has mass, I've always believed that inertia is an
inherent barrier to what
can be achieved practically with vinyl playback, similar to
quantification parameters being the potential barrier with
any particular digital format.

Nice post, Frogman. I would agree wholeheartedly. I am also thinking that the phenomena you describe are also a good answer to a question that has been discussed on this forum quite a bit lately, namely what is PRAT? Too many audiophiles think about timing only in terms of the technical specs, the actual speed of the turntable, for instance. What you describe is a different kind of timing that is far more important, and this to me is the "timing" implied in the term PRAT.

11-07-11: Unsound
Hifihvn, no, not unless the analog tape's sampling is very much larger than microscopic.
Unsound (System | Threads | Answers | This Thread)

After thinking about it more, we do hear the hiss from audio tape, even on the masters. I actually wonder if it does play games with the bit-stream when this same type of tape is used for digital?

11-07-11: Atmasphere
My guess though is that when we can do 64-bit DACs on a regular basis that digital will start demonstrating the promise that its been showing.

Thanks, Ralph. It seems to me, though, that it would be a pretty safe bet that that will never happen. In fact I suspect it is theoretically impossible, due to Johnson noise, shot noise, etc. Quantization of a 2 volt full-scale range into 64 bits would mean that the least significant bit corresponds to about 0.0000000000000000001 volts. (That's 18 zeros between the decimal point and the "1").

Intuitively it seems to me that although as you say the Nyquist theorem assumes unlimited resolution of the samples, 24 bits or so should be precise enough to be just as good for all practical purposes.

Best regards,
-- Al

Jump on CD if you think its great its your taste!!

EBM, even limited to the analog domain, vinyl isn't even a pretender to the throne.

Hifihvn, no, not unless the analog tape's sampling is very much larger than microscopic.

Ralph, what do you feel is the more significant limiting factor for redbook, sample rate or bits per sample? Just curious.

Well, the Nyquist theorem is looking for an exact sample (IOW with no limitation of resolution) in order to work, by definition it is the number of bits that is the real problem. When you think about it, this can only really be done in the analog domain...

My guess though is that when we can do 64-bit DACs on a regular basis that digital will start demonstrating the promise that its been showing.

I was wrong about the IBM PC being king when Redbook was devised. It was more like the Commodore 64 :)

In the fields of science, engineering, industry and statistics, the accuracy[1] of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual (true) value. The precision[1] of a measurement system, also called reproducibility or repeatability, is the degree to which repeated measurements under unchanged conditions show the same results.[2] Although the two words reproducibility and repeatability can be synonymous in colloquial use, they are deliberately contrasted in the context of the scientific method.
Accuracy indicates proximity of measurement results to the true value, precision to the repeatability or reproducibility of the measurement

A measurement system can be accurate but not precise, precise but not accurate, neither, or both. For example, if an experiment contains a systematic error, then increasing the sample size generally increases precision but does not improve accuracy. The end result would be a consistent yet inaccurate string of results from the flawed experiment. Eliminating the systematic error improves accuracy but does not change precision.

A measurement system is designated valid if it is both accurate and precise. Related terms include bias (non-random or directed effects caused by a factor or factors unrelated to the independent variable) and error (random variability).

The terminology is also applied to indirect measurements—that is, values obtained by a computational procedure from observed data.

In addition to accuracy and precision, measurements may also have a measurement resolution, which is the smallest change in the underlying physical quantity that produces a response in the measurement.

In the case of full reproducibility, such as when rounding a number to a representable floating point number, the word precision has a meaning not related to reproducibility. For example, in the IEEE 754-2008 standard it means the number of bits in the significand, so it is used as a measure for the relative accuracy with which an arbitrary number can be represented.

RE***Which is more accurate: digital or vinyl?****

How many roads must a man walk down before you call him a man?

How many chucks must a woodchuck chuck if a woodchuck could chuck wood?

One of the most thoughtful, and poetic attempts at answering this
question appears in Peter Ledermann's answer to Neil Gader's question in
a recent interview:

"Aside from it's ease, warmth, and feel-good sound, it (analog) is
approachable, do-able, difficult, and satisfying to master and accomplish.
It is a hoop shot from across the court. Impossible to sink, but, when it
works, makes you stand up and dance. It is visceral as opposed to virtual,
marvelously and delicately ephemeral in contrast with the concrete yes
and no of digital."

I love that. I would like to offer a different perspective from what has been  
discussed mostly so far, and which points to what I think Ledermann is
saying. I won't get into the technical issues as my understanding of them
is limited, and some can do a much better job than I (thank you Ralph).
But, I know what my ears tell me, and I trust them. I believe that both
technologies are capable of excellent sound (obviously), and there are
obvious tradeoffs involved with each. I have made a living trusting my ears
for thirty five years, and their message is pretty clear.

More times than not, when this discussion comes up, the opinions as to 
one technology's superiority or inferiority revolve around tonal issues. One 
is considered brighter or warmer than the other, high frequency cut-off
points, etc. But to me, the main issue with digital vs. analog is not tonal or
timbral. It has to do with what I think Ledermann is alluding to: the feel-
good quality of analog. Whatever the issues may be with sampling rates
that many feel are responsible for tonal resolution deficiencies or
limitations with digital are, to me, even more important as concerns their 
effect on time and dynamics. Time is where the soul of music lies. The
ability to capture the extremely subtle gradations in dynamics and rhythm
that musicians use to convey a message is where the difference between 
the two technologies is most obvious to me. The grooves set up by James 
Brown's rhythm section are always a little deeper with good analog. The
difference between the softest and loudest moments in a crescendo by a
great string section in an orchestra is always more exciting with analog.
Even when digital offers a louder ultimate volume, what happens between
the softest and loudest points is more coherent, more vibrant, with good
analog. The difference may be subtle, but it is real to my ears. Those are
the subtle details that give music meaning and excitement. It is ironic,
since digital has the theoretical advantage when it comes to speed
stability. But time accuracy between point A and point B does not a groove 
guarantee. What happens between those two points seems to matter a
great deal.

There is a saying among musicians: "No-one ever got fired for
having a bad sound". What is meant by that is that what matters
most is not the most beautiful sound, but the ability to play with good time
(rhythm).

"what do you feel is the more significant limiting factor for redbook, sample rate or bits per sample?"

I'm clearly not answering for Ralph, but for me I think it is the sample size that is the performance bottleneck for me, if there is one. I say if there is one becaue I still am not 100% convinced that the CD redbook format itself is deficient in any practical sense.

I say the sample size in that one of the things that I am not totally convinced CD redbook can match relative to vinyl is the ability to sustain a truly consistent level with the higher frequencies due to random variations associated with the sample magnitude value. The audible effect can often (but not always?) be subtle variations in pitch and/or high frequency transients such as those produced by massed strings, where extremely subtle transients are in play. Relatively few digital rigs do this well enough to challenge vinyl from what I have heard, but I have heard it done well so I believe it to be possible, which would mean that the implementation in play with most systems and not the format itself is the culprit.

I have heard a/b comparisons between CD and vinyl and even R2R where the analog formats clearly beat the digital, but again, I cannot say for certain that the CD format was the culprit as opposed to aspects of comparing different actual recordings in each format.

Ralph, what do you feel is the more significant limiting factor for redbook, sample rate or bits per sample? Just curious.

FWIW, my instinct has always been that sample rate is the more significant issue, at least for most music. In fact I've been amazed at times at how good SOME cd's can sound, given the seemingly absurd 10% margin with respect to the Nyquist rate.

Best regards,
-- Al

I'm stumped on that one. Why is that?

re-read my previous posts. The Nyquist theorem is poorly applied.

I will add that until human perceptual rules are understood and kept in mind during the design of the 'next' digital codex, digital will continue to display the same colorations that it does now.

One last point is also obvious- digital audio showed up in the early 1980s, about 3 decades ago. Yet analog is still very much alive, with 1993 being the year of the least vinyl production. If digital was really 'more accurate', 'better' or anything like that, it would have been able to supplant the prior art in that time. I can name plenty of examples wherein that has happened on other fields. Its not happened in audio because digital has failed to bring home the promise. I don't think anyone takes 'perfect sound forever' seriously anymore :)

"Vinyl is king."

Small kingdom?

Vinyl is king.HELLO!!

I suppose one could make the argument that on the molecular level, analog tape provides no more than random samplings.
Unsound (System | Threads | Answers | This Thread)

Then if you take that same tape with its particles and use if for a digital recording, maybe you'll get different digital defects?

I suppose one could make the argument that on the molecular level, analog tape provides no more than random samplings.

"digital will *never* (which is a very long time) be better than analog- to do so would violate the laws of physics"

I'm stumped on that one. Why is that?

Even if so, I'd have to believe the difference would become somewhere between insignificant and essentially nil to pretty much all at some point if it has not already.

I think it was Mr Spock who I recall once saying:

"A difference that makes no difference is no difference"

Hard to argue logic with those Vulcans.

Just wondering how good is your hearing at 19-20Khz?

Certainly not as good as it was...

Bandwidth problems can be heard without 20KHz response in the ear though. A cutoff at 20KHz has artifacts that extend down to 2KHz. This is why amps and preamps endeavor to have wide bandwidth- to reduce audible phase shift components well within the audio passband.

Most high quality analog formats can extend well past 20KHz (remember CD-4 from the 1970s?); my 1/2" tape machine can do 30KHz passably well at 30ips. Even though you can't hear that high, you sure can hear how much more resolution it has!

One of the keys to superior CDs these days is higher scan frequencies during record mode. We use 88.2KHz 24 bits as a backup of our analog recordings. 88.2KHz is nice because there is no algorithm required to produce a Redbook file, and you don't need a brickwall filter during record mode either. My point here is that Redbook is intentionally limited and compromised, and as long as it is around digital will *never* (which is a very long time) be better than analog- to do so would violate the laws of physics.

I don't think anyone should blame consumers for rejecting other digital formats like SACD... they already got talked into selling a perfectly good LP collection to be replaced by bright-sounding soulless junk. Collectively I don't think they trust the audio industry anymore.

"The reason for no new formats is that there has been adverse consumer reaction to updating technology."

If CDs were inherently problematic this would probably be less true. The fact is they have held up quite well for 30 years.

The market for CDs at least in most economically mature countries around the world is probably saturated at this point. The fact is there is more music out there today and still in circulation between vinyl and CD formats than ever before.

Plus the competiton now comes from otehr streaming digital music sources readily available for free or for cost also with very good quality via internet.

Plus the end user experience possible with all these digital sources out there and so many ways to access and use them is richer than ever. Most people care about other aspects of the listening to music experience in additional to whatever degree they may care about how good it sounds.

"The main reason CD is still around I suspect and has not been replaced has more to do with it being a very good solution than it does with our digital audio technology cannot cut it even these days."

This is totally wrong. The reason for no new formats is that there has been adverse consumer reaction to updating technology. Few fewer CD's have ever been sold than originally thought probable in the original business plan for CD. Consumers are resistant to go and buy their whole music collection again.
We audiophiles are a very very minute population in the scheme of the music market.

Now of course IPOD's and computers have leapt into the fray.

The market has simply moved on.

Nyquist theory also applies in digital imaging, an area in which I am more technically familiar with from experience than digital audio.

What's missing in your digital camera images, or even in you digital HD TV picture?

What are your expectations? There is clearly something missing compared to live, but how much does it matter?

Digital audio including redbook CD format is very analogous.

Would you give your HD TV the boot and go back to analogue TV? What's missing there?

And IMAX is right out.....

CLearly if CD was an inherently flawed and outdated technology, newer hi res formats would have replaced it by now. You really think good digital audio is harder than good digital video? Guess again. The main reason CD is still around I suspect and has not been replaced has more to do with it being a very good solution than it does with our digital audio technology cannot cut it even these days.

Its funny to even think that if you look at the world around you and see with your own eyes what digital is capable of.

11-04-11: Hevac1
When recording say a violin, is the first sample taken at the start of a note played and does it also sample at the very end of the note regardless of the samples in between? If it does not then how can digital play back components perform proper decay and bloom of the music played regardless of the sample rate?

There is no synchronization between the start or end of a musical note, or anything else involving the timing of the music, and when the samples are taken. But keep in mind that notes don't start infinitely fast, and don't end with infinite abruptness. The speeds that are involved correspond to the highest frequency components of the note. If all frequency components that are audibly perceptible can be captured with sufficient accuracy (whatever that may mean), then nothing is lost.

If I sit and play an instrument for recording purposes onto an analog tape I will record all that I play. Is this also true for digital recording or is the device recording parts of the sound (sampling) I am playing and the computer puts it together sort of like digital morphing of one image to another.

It will record (and the digital data will contain) all that you play, but only up to around 20kHz, and with accuracy that is less than perfect in a number of ways (quantization noise reflecting the finite number of bits per sample, frequency response ripple and phase shifts resulting in part from the low pass filtering that must precede the a/d converter to prevent aliasing, etc.).

The d/a conversion process does not, at least conceptually, involve adding information, combining images, interpolating between samples, or anything along those lines. Conceptually, once the digital data for each sample has been converted to a corresponding voltage it just involves REMOVING (filtering out) ultrasonic (higher than 20kHz) frequency components that are present in combination with the musical information (at frequencies below 20kHz). It is the presence of those ultrasonic spectral components that are what distinguish a sampled waveform from a continuous non-sampled waveform containing the same information.

Your questions are good ones, though, as it's all pretty counter-intuitive.

Good answers from Ralph & Mapman, also.

Regards,
-- Al

Atmasphere,

Just wondering how good is your hearing at 19-20Khz?

I am 52 years old. I do not hear those frequencies anymore as best I can tell.

When I was a young punk 18 year old budding audiophile, I recall getting up there pretty good with test tones and such.

Maybe thats why good systems sound better than ever to me these days in general?

"If I sit and play an instrument for recording purposes onto an analog tape I will record all that I play. Is this also true for digital recording or is the device recording parts of the sound (sampling) I am playing and the computer puts it together sort of like digital morphing of one image to another. If it is the latter then why call it a sample you are just asking for trouble and confusion."

Both are somewhat imperfect reproductions of the original using two different approaches. The question is always "how somewhat????" and how much do whatever teh differences are matter? That is true be the approach digital or analog. We live in an imperfect world. There is no such thing as a perfect reproduction in most any case. The 16 bit sample size for CD redbook is perhaps the prime bottleneck with teh CD redbook format, but as ATMAS noted 16 bits gets you a lot of resolution ie 2 to 16th power individual levels.

I think that bottleneck can be heard in some cases, but not all and is very difficult to determine when done right, at least that is my subjective assessment having heard both really good analog and really good digital.

If I sit and play an instrument for recording purposes onto an analog tape I will record all that I play. Is this also true for digital recording or is the device recording parts of the sound (sampling) I am playing and the computer puts it together sort of like digital morphing of one image to another. If it is the latter then why call it a sample you are just asking for trouble and confusion.

Yes. Nyquist assumes an analog sample of unlimited resolution, not a 16-bit sample. Its application to digital audio is thus, not. Ah, people don't like to talk about this! Or they do but it just turns into a ridiculous argument. But I suggest anyone look into the life of Nyquist:
http://en.wikipedia.org/wiki/Harry_Nyquist

(you will note that Nyquist had no concept of digital audio back when he proposed his sampling theorem)

and

http://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem#The_sampling_process

If you read carefully, you will note that the samples are not defined as '16 bit', instead they are samples of the 'bandwidth-limited' signal, which have an analog value.

Now 16 bits can define a fairly precise value, but that is by no means the same as saying it can define the exact value. Further, the significance of 'bandwidth limited' should not be ignored. Current Redbook specs put the sampling frequency at 44.1KHz, if you think about it, the significance is that anything above about 19-20Khz is ignored. It is not so much that Nyquist is out to lunch that it is that Redbook specs are poorly applied.

The Redbook specs were created in the late 1970s and early 1980s. Seems to me I heard one of the first CD players about 1981. Back then, the IBM PC was king; a $10 cell phone has *considerably* more computing power! IOW, Redbook was **intentionally** limited in order to cope with the limitations of the hardware of the day. It is quite anachronistic that we still take it seriously today...

"The missing information from the digital samples must be added by the play back component, correct?"

This is incorrect, at least in theory. Read up on the Nysquist sampling theorem for more information.

Assuming the theory is sound, then the sampling is sufficient to capture all the information including high frequencies that matter, ie that most humans, even those with the best hearing, are capable of hearing.

Of course, not everyone may agree that the theory is sound and that the CD redbook implementation specifically is sufficient to capture everything that matters.

Then as you get into higher resolution digital audio sampling formats, the possible issues become even less likely to be real, so hi res is an insurance policy at minimum of sort.

The CD redbook format I think was well done in the sense of applying the best theory at the time towards being good enough to deliver very high quality sound, however, practically, a line had to be drawn in the sand at at that time now about 30 years ago regarding what was sufficient moving forward yet practical from a data volume and processing perspective at a commercial scale.

That fact that newer hi res formats have not caught on faster than they have 30 years later when the technology is far more advanced is testament actually to the robustness of teh original CD design.

NEwer CD recording and playback systems I find do increasingly better jobs of producing better recordings (when teh producers choose to) and a lot of progress has been made since CD was started in regards to providing better playback peformance with the now 30 year old format.

So it is extremely grey at best whether or not even the 30 year old redbook CD format is really missing anything of consequence to most as predicated by the theory it was based on.

Of course there may be "golden ears" out there that can hear something missing perhaps, but I take that with a grain of salt as well in that I do not know of any authority that certifies individuals as having golden ears.

I am not up to date these days unfortunately on the theory behind digital audio, so I am not sure if there is any newer theories out there or refinements to teh Nyquist principles applied 30 years ago that would indicate cleary that teh CD redbook format is now technically lacking in theory.

Maybe others know of something?

Question about digital sampling. The missing information from the digital samples must be added by the play back component, correct? When recording say a violin, is the first sample taken at the start of a note played and does it also sample at the very end of the note regardless of the samples in between? If it does not then how can digital play back components perform proper decay and bloom of the music played regardless of the sample rate?
I know nothing about digital recording but feel it is missing the soul and heart of the music IMO.

When you bake a tape, it takes a few years for it to regain the moisture chased out while baked. IOW, you have plenty of time to work with the tape- certainly more than 48 hours.

The reason you have to bake them has nothing to do with whale oil :) Modern tapes are made with polyesters, which can absorb moisture at the ends of broken molecular strands. The water molecule allows the magnetic substrate to come unglued. Baking chases out the moisture so the substrate can function normally.

Older tapes from the 1950s were made with acetate. Acetate does not have the moisture issue, so although they have less performance and break easily, they do store much better.

The tapes were baked because they used a synthetic tape lubrication not whale oil based lubricant. Overtime they became unplayable. Record companies were in a frantic panic to find a solution. The solution? Bake the tape. It can be played back within I think 48 hrs. You can bake it again, but don't know how many times! Steely Dan goucho had to be re-baked to do the sacd version.