Digtal vs Analog; Why Isn't Digital Better? (long)

[DizRotus]

Analog versus Digital; why isnt digital potentially superior?<1>

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Is it possible to plumb the collective expertise of Forum members regarding the differences between the analog and digital recording processes to see which has the most ultimate potential? And, to do so without debating which presently sounds better or worse to individuals?

This post is not:

Arguing that vinyl sounds better or worse than digital;

To convince vinyl lovers that theyre mistaken to always or frequently prefer vinyl over digital; or

Suggesting that subjective opinions regarding the relative merits of analog versus digital are right or wrong.

I understand that many here believe that certain vinyl records sound better than their digital counterparts; I have experienced the phenomenon myself. I also understand that many here believe that digital recordings generally sound better. So please dont spend too much time with anecdotal comparisons of specific subjective comparisons of vinyl to digital.

What I would like to shed some light on is why digital is not inherently superior to analog? If, in theory it is superior, why isnt it superior in application?

IMHO the ultimate object of the recording and playback of music is convert the mechanical energy (sound wave vibrations) of the music into electrical energy (via microphones and/or pickups) and then covert the electrical energy back to mechanical energy using a transducer (speaker) that vibrates the air to reproduce as faithfully as possible (i.e., high fidelity) the original sound.

How can dragging a stylus through a modulated groove more accurately accomplish that goal than digitally converting the signal into a theoretically infinite number of ones and zeros to capture each subtle nuance? It seems to me that, done properly, digital should surpass analog for the purposes of high fidelity. Never mind the associated problems of dust, scratches, record wear, etc. that are attendant with the vinyl medium. With each at their best, why isnt digital superior to analog?

Part of the problem seems to be that the audio hobby is not conducted in a scientific manner. Good scientific experimentation requires that only a single variable be changed at a time. This is not how we form subjective opinions regarding things audio. I believe almost everyone would agree that some vinyl recordings are excellent and some digital recordings are abysmal, and vice versa. But is this a valid comparison of the inherent potential of the two media, or a comparison of good recordings by the artists and producers versus bad recordings?

In a perfect world, it seems that we should be able to preserve the best recordings (whether analog or digital) as a stream of ones and zeros to be later transformed back into mechanical energy in true high fidelity. We seem to be far from that point. Am I all wet, or is this a matter of the market not demanding that mass produced recordings on digital media be produced with the same attention to detail and quality that were evident in the past, when vinyl was the only source of high fidelity?

<1> As background, after years of using SS amps to power inefficient LS3/5a speakers, I now prefer tube (analog) power and efficient Cornwalls for listening to music. Nevertheless, I have heard some digital amps that sound quite good. Before I returned to Klipsch, I sold my modified AR turntable with SME III tonearm and most of my vinyl, which I now feel was a mistake. My current music sources are FM (NPR and CBC) and CD.

[Klewless]

There is probably a million answers to your question!

Here is a summary of my feelings on the subject.

1. Digital is superior to analog records. Try listening to the new SACD releases of the Mercury and RCA 3-channel recordings made in the 50's.

2. I try not to relate the quality of the source and the skills of the producers with the medium of delivery. Both digital and analog products have released some very good and pleasing sounds, in spite of each type's "problem areas".

3. Remember that the industry seems bent on producing inferior products these days "in order to protect their interests" (my interpretation of copy protection). Most people could care less about the quality of their sound systems. There are the dedicated few who do care, and care deeply about it. I try to fit myself into the second group.

I know that I did not address each individual question but I hope that the big picture is what eventually shines. I am aware of each of the issues you pointed out and agree with each one cited. Nothing is perfect, not even the live events! Even the mood of the audience can affect the performance of the players.

I love my old records. I also love my CDs. And now, I love my SACDs. I do not have audiophile equipment (Marantz home theater and universal player for the digital decoders).

And to further confuse the issue, sometimes I let the receiver decode the signal and sometimes the player gets that job. Each sounds slightly different with neither owning the preference.

All this is just my opinion and hope it helps a bit.

[DrWho]

Well then, the original proposition we should then turn to the people in the studio that get to compare the original sound between the playbacks from any kind of medium onto which they recorded it.

I personally have had the opportunity to record many things simultaneously to DAT, to a computer at 96kHz, to audio cassette and to a multi-channel analog reel to reel setup. In all honesty, the computer at 96 was always the absolute "best" sounding in that it most closely matched the original input signal. By no means would I consider these recordings of significant quality or whatever...in fact, I was rather young when I started making the comparisons too (12 years old). I suppose that makes me a more unbiased opinion though because I had no clue what was going on at the time. Since then, I've occasionally conducted the tests over and over just to verify it again and again with new equipment. I only mention this to put my opinion into perspective...I'm sure others might even have had the opposite experience.

However, I would like to call attention to tube guitar amps. The reason they can sound so "good" is because that tube distortion sound is just so powerful and clean, yet technically it's so totally distorted it's rediculous. The reason I bring this up is that this is an example of when we don't want the original sound!

I know it may be a stretch for some, but I would propose that the end goal of our playback systems really is not to perfectly playback the recorded medium. Instead, the real intent is to make it sound as good as possible to our own ears. When it comes down to it, don't we judge upgrades by their ability to increase enjoyment?

When it comes to analog versus digital, analog definetly has more distortion. You can totally hear it in the studio (I recommend doing this if you ever get the chance). However, many (including myself) simply enjoy the distortions in analog more.

It is most interesting to note however that you can record an analog signal onto a digital format and you now have the analog sound recorded on a "better" (technically) format. One trick I love to do is take those adapters that they make for you to plug a walkman into the tape player in your car. Instead of a walkman, I love to run guitars or drum mixes through a tape head like this and get it swallowed up in the tape head distortion. Of course I'll record it to digital, but this is a sound that you can only get with a tape deck. I'll see if I can't make a recording if anybody shows interest.

Anyways, take your LP's and record them to CD and compare the sound. Then take some original CD's and record them to LP and compare the sound (I know it's not exactly something we can all do). Recording your CD to the LP should sound better (at least it's been my experience that it works this way). Since garbage in = garbage out, this means that the CD is the better medium...we just need to add the "LP effect" to make the CD sound subjectively more enjoyable. I think it would be interesting to find a device like the tape adapter that would provide a groove for the stylus to follow...

[DizRotus]

DrWho-<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

I think youre onto something. I now prefer the sound emanating from my Cornwalls via relatively low powered tube equipment. I have no doubt that distortion (i.e. less than high fidelity) might be, in part, responsible for the observed preference.

Your guitar amp analogy and LP to CD vs. CD to LP analogy are very interesting.

[DizRotus]

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10:02:08 AM Klewless wrote: <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

I love my SACDs

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I confess Ive not yet experienced SACD.

Ive avoided it because, Im afraid Ill like it.

[LarryC]

I think that, while digital represents a tremendous accomplishment in ably deconstructing and reconstructing music signals, that process does not make digital reproduction a reference standard by any means. One can put a lot of coin into esoteric digital playback that can hold its own against vinyl and even be superior in some ways though it still sounds somehow different. One can also put a smaller amount into analog playback that will make a lot of digital sound rather lifeless and artificial by comparison, and that seems to be the common experience on the Forum.

In other words, playback plays a great part of determining the potential outcome of recording processes. I believe there are no absolutes here.

Larry

[dragonfyr]

They address two different 'things'.

Like it or not, the world is analog.

The only advantage to digital is that, once a signal is (properly!) converted to the digital domain, that processing is a much more precise process.

But ultimately it still has to be converted back to analog.

[SilverSport]

I think you need to address the question of "are we looking for the "best" (whatever that is) sound or the sound we are used to?

I see several mentions on this forum of vinyl being better...perhaps to those of us who grew up on vinyl it might be...TO US...then someone listening to a different type of music says they prefer CD recordings...because, perhaps that is what they are used to...

I have a "decent" table, certainly not what many of you "vinyl-o-philes" use but better than some of the cheapies out there, along with a decent cartidge...right NOW I prefer CDs to vinyl (horrors ) but who knows what's next...

Incidently, I never liked 8-track but I had them in their time and I bought a decent (Nakamichi) cassette deck but never really thought THAT was anything great...I liked reel to reel but sooooo expensive for me at that time...now I find I like CD on a cheapie player (Toshiba 3950) after having far more expensive players, as much as anything....of course I now have Heresys and K'Horns so that MIGHT have something to do with it.

Just my .02

Bill

[3dzapper]

Here in a nutshell is the reason. Granted this "sinewave" is sampled at 16Kilobytes/sec and a 96KPS looks "better", it is still sampled at a finate rate not continously as an analog source is. If a pure sine wave looks this bad, one can imagine the details and intracasies that are missing from the digitally sampled source. Edit: I forgot to mention this is from a $9000 list Ensamble Diondo CD player.

Each advance in digital technology is a step in the right direction. Maybe at some point the sample rate will get to a point where all the music is there and the device does not have to fill in the gaps with it's sometimes faulty logic.

Source: Streeophile, Mar'05

YMMV!

Rick

[sunnysal]

and what does the same sine wave look like when played back from an lp? and a square wave played back on the two mediums? records that were mastered unto laquer at 45rpm speed sounded better than 33rpm masters right?

how much of the love of vinyl comes from taste and not from accuracy? it seems a lot like the argument between tube lovers and SS lovers, only in reverse!

play what "get's your rocks off" I say. regards, tony

[DizRotus]

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1:38:06 PM

3dzapper wrote: <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

"Here in a nutshell is the reason. ... Maybe at some point the sample rate will get to a point where all the music is there and the device does not have to fill in the gaps with it's sometimes faulty logic."

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Now this is just the type of input I hoped this thread would generate.

It seems, Rick, that you're saying that an analog cartridge traces a groove and generates an infinite number of varying electrical impulses that duplicate the original, in the example a Sine Wave, but the finite sampling rate of digital truncates the Sine Wave. Do I understand it correctly? If not, where have I gone astray? If so, is an increased sampling rate the answer?

Your post seems to an offer objective explanation for subjective differences.

[3dzapper]

Neil, you've got the idea. As the sample rate has increases and with the advent of real new digital technologies such as SACD, digital gets closer to analog. Perhaps the next generation using blue lasers can considerably close the gap.

The limiting factor for both digital analog reproduction is found in the trade offs of data stored v recording time. In analog, the limiter is found in the base regions. The wide groove modulations required for base transients takes up much precious room on the disc surface. In digital it is bit space, higher sampling rates need more storage capacity.

As Tony noted, an LP cut at 45 RPM has finer detail than at 33 at the expense of content time. It does this by passing the modulations under the stylus in a longer groove/sec than at 33.

If the first of the following were scanned at the rate of a 33 and the second at 45 in one second, it can be seen that the latter has more information availiable but will require 50% more surface area:

.................................................

...........................................................................

The first has 50 bits of information in one second, the other has 75 bits.

Tony, I will get a picture and we'll see. Now to dig out the Shure test record and O'scope.

Rick

[sunnysal]

thanks rick, that'll be VERY interesting. tony

[sfogg]

Rick,

Look at the recording level of the picture you posted. That the wave looks bad has *nothing* to do with the sampling rate and 'guessing' on the signal. The reason it looks bad is because it is just about at the noise floor of the CD system. That signal is -90dB down in level compared to the max signal level CD can reproduce. That is just about meaningless, very very few people have systems/room that can support 90dB of dynamic range. An awful lot of people don't even have 40 or 50dB of dynamic range in their systems. Not to mention how compressed much music is.

Try looking at the signal from vinyl playback at -90dB down... it is going to look *far* worse and will be totally swamped by the noise in the system.

Look at a sine wave output of a digital system higher up in recording level (using more bits) and the sine wave will look exactly like the input as long as the analog signal is below half the sampling frequency of the system.

Shawn

[sfogg]

" The reason it looks bad is because it is just about at the noise floor of the CD system. That signal is -90dB down in level compared to the max signal level CD can reproduce. "

Forgot to mention... for those that don't know this means the 1kHz test signal is about 6dB above the theoretical (in a perfect system) noise floor of the redbook CD system. In other words this signal is being reproduced in a system that has, at best, about of 6dB S/N ratio... that is why it looks lousy. It is effectively a 44.1kHz *1* bit system. And as the picture says it is undithered, proper dithering would improve the low level linearity somewhat.

Shawn

[3dzapper]

I chose that example because it is so graphic. It represents what will be seen in a quiet passage at 16 bits resolution.

Like the graph you made in high school, that turned out to be an elipse, the holes between the dots must be extropolated. 44 or even 96 KBPS must be still be "constructed" by the DAC's "logic" to fill in the waveform. No matter how mant bits you add, the waveform will still be a semblance of the original until the sample rate reaches into the mega BPS range. That may be possible with the 27 gigabyte (soon 50 GB)storage capacity of the Blue Ray technology. It is not feasable with 700 meg CDs or 4.7 gig DVDs for that matter.

[3dzapper]

For those interested in what we are talking about:

"dBFS - dB Full Scale

0 dBFS represents the highest possible level in digital gear. All other measurements expressed in terms of dBFS will always be less than 0 dB (negative numbers).

0 dBFS indicates the digital number with all digits ="1", the highest possible sample.

The lowest possible sample is (for instance for 16 bit audio):

0000 0000 0000 0001, which equals -96 dBFS. Therefore the dynamic range for 16-bit systems is 96 dB. For 20-bit digital audio it is 120 dB. For 24 bit digital audio it is 144 dB.

Full-scale input level is the analog input voltage level that will cause the A/D converter to just equal full scale with no clipping on either positive or negative peaks.

Output full scale is defined as the analog output voltage produced while playing a 997 Hz digital full-scale sine wave, assuming the THD+N is less than -40 dB relative to the signal level.

The dynamic range of a digital system is the ratio of the full scale signal level to the RMS noise floor."

Source:http://www.jimprice.com/prosound/db.htm#dBFS

[LarryC]

Questions from someone sub-newbie in this area: what is the "linearity" Sfogg referred to, and what is dithering and how does it improve linearity?

Thanks -- Larry

[sfogg]

Rick,

"I chose that example because it is so graphic. "

And what it is showing isn't what you think it is showing.

I assume you have some test CDs in your collection? Find one that has 1kHz sine wave test signal recorded on it. Ideally you will have one that has 1kHz test signal at different recording levels working all the way from something like -90dB up to 0dBfs.

Go plug the output of your CD player into your 'scope.

*IF* what you are saying is correct, in that the distortion in that picture is caused by the sampling rate, then the recorded level will have no effect on what you see on your scope as the sampling rate hasn't changed in any of those tracks.

However, if you actually do this (and I strongly suggest you do) you will find that the distortion you see at -90dB will be *gone* completely when the recorded level is raised to typical levels on the CD. The sine wave you will see on your scope will look no different then if you plugged your function generator directly into your scope.

Therefor the distortion on the picture you posted is *not* related to the sampling rate. It is simply related to the noise floor of the system.

Try it yourself, you will see what I am saying is accurate.

" 44 or even 96 KBPS must be still be "constructed" by the DAC's "logic" to fill in the waveform. "

Not true, the DAC does no such thing. The DAC simply plots out the sampled points, it is the analog reconstruction filter which turns those points back into the smooth continuous waveform. The reconstruction filter is really nothing more then a low pass filter.

Per Nyquist if you can sample a wave at more the two points per cycle you can accurately reproduce it. What that means is that below 22kHz the 'capture/playback' of a wave is not improved by moving from a 44.1kHz sampling frequency to a 96kHz sampling frequency or even to far higher then that. *All* you get from increasing the sampling rate is to increase how far up in frequency you can capture.

"No matter how mant bits you add, the waveform will still be a semblance of the original until the sample rate reaches into the mega BPS range."

You are mixing up the bit depth of a signal and the sampling rate of the signal. They are not the same thing, they both have to do with a different aspect of the capturing.

Sampling rate tells you the maximum analog frequency the system can 'capture' to. It is just under 1/2 the sampling frequency.

Bit depth describes the theoretical maximum signal to noise ratio of the system. Each 'bit' is basically 6dB of S/N. So a 16 bit system has, in theory, a max of 96dB S/N. A 24 bit system has a max, in theory, S/N of 144dB.

Shawn

[3dzapper]

Then Shawn, why don't you explain why an analog recording sounds better than any digital format currently available?

Rick