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Vinyl vs Digital and 24 bit vs 16 bit from vinyl.
SoAnIs
post Mar 5 2008, 10:20
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24-bit precision gives you about 16.77 million values. Assuming a total groove width of 50 x 10^-6m, the maximum movement of the cutter is physically bounded at about half that. Much more and the cutter will be in the space for an adjacent groove. Thus, 50 microns width divided by 16.77 million gives us about 3 x 10^-12m, i.e. ~0.03 angstroms.

The diameter of a hydrogen atom is 1.0 angstroms (1 x 10^-10m). That would make the resolution of a 24-bit digital signal equivalent to an analog cutter whose resolution is just about 1/30 the width of a hydrogen atom. Sadly, this seems to be physically impossible, as none of the particles smaller than atoms are stable enough to be used in records.

Of course, records aren't made of hydrogen, they're made of the polymer pvc. One molecule of pvc is about 100,000 angstroms. This means that, if the cutters were actually removing single pvc molecules the vinyl records would have about 11 bits of resolution. Sadly, they don't get even that precise, though I'm not sure the actual precision. To get down to a record made of hydrogen atoms (possible under very low temp/very high pressure I suppose) one would need 19 bits. Anything beyond that is useless as long as the laws of physics hold.

Therefore, all other things being equal, digital is superior to vinyl. That said, mastering on CDs is often terrible while the mastering on records is often made somewhat better. This varies from CD to CD and record to record, and CDs are technologically far superior to records.
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digital
post Mar 5 2008, 12:33
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Dig that crazy math man! Speaking as a huge vinyl fan; you're absolutely right! As much as I really love the LPs, funky sleeve notes and great graphic cover art - I'll take CD every time if given a choice of which ‘sounds better’ – mastering / productions caveats aside.

Andrew D.
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pdq
post Mar 5 2008, 13:11
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Not to be too nit-picky, but vinyl records aren't cut directly but are molded from a metal master, so the limit would be the diameter of a metal atom, which is much smaller than 100,000. Also, if they were cut directly in vinyl, the cutter needn't remove whole molecules but would readily break bonds as needed to remove part of a molecule.
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Nick.C
post Mar 5 2008, 13:22
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QUOTE (pdq @ Mar 5 2008, 12:11) *
Not to be too nit-picky, but vinyl records aren't cut directly but are molded from a metal master, so the limit would be the diameter of a metal atom, which is much smaller than 100,000. Also, if they were cut directly in vinyl, the cutter needn't remove whole molecules but would readily break bonds as needed to remove part of a molecule.
But the metal master has to have been created in some way....


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Jens Rex
post Mar 5 2008, 13:29
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Best first post in years.
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pdq
post Mar 5 2008, 18:19
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QUOTE (Nick.C @ Mar 5 2008, 08:22) *
QUOTE (pdq @ Mar 5 2008, 12:11) *
Not to be too nit-picky, but vinyl records aren't cut directly but are molded from a metal master, so the limit would be the diameter of a metal atom, which is much smaller than 100,000. Also, if they were cut directly in vinyl, the cutter needn't remove whole molecules but would readily break bonds as needed to remove part of a molecule.

But the metal master has to have been created in some way....

Indeed, and that's where the diameter of a metal atom comes in.
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Axon
post Mar 5 2008, 18:39
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But the contact area of the stylus covers many thousands of molecules, and PVC deforms elastically. So the actual traced waveform could have a resolution that is considerably more accurate than that implied by the size of a "single" PVC molecule, at the expense of some time resolution (which due to tracing distortion really isn't there anyway).

What exactly is a "single" PVC molecule, anyway? PVC is a chain polymer. It might be 100000A on its long axis, but each member of the chain is what, H3C2Cl? That can't be more than 50A. So even ignoring the contact area argument, you may be off by a few orders of magnitude on the size calculations.

I'm all for bashing vinyl, and I agree that you're unlikely to get more than 12 bits out, but I think this math is too sloppy to support that.

This post has been edited by Axon: Mar 5 2008, 18:41
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pdq
post Mar 5 2008, 19:27
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QUOTE (Axon @ Mar 5 2008, 13:39) *
But the contact area of the stylus covers many thousands of molecules, and PVC deforms elastically. So the actual traced waveform could have a resolution that is considerably more accurate than that implied by the size of a "single" PVC molecule, at the expense of some time resolution (which due to tracing distortion really isn't there anyway).

What exactly is a "single" PVC molecule, anyway? PVC is a chain polymer. It might be 100000A on its long axis, but each member of the chain is what, H3C2Cl? That can't be more than 50A. So even ignoring the contact area argument, you may be off by a few orders of magnitude on the size calculations.

I'm all for bashing vinyl, and I agree that you're unlikely to get more than 12 bits out, but I think this math is too sloppy to support that.

PVC consists of alternating CH2 and CHCl units, so in theory when cutting through the vinyl molecule you could cut to this small a unit by severing the molecule at a C-C bond. In reality none of this matters because the cutting is actually done on a metal master and not the vinyl.

Edit: SOME masters are cut directly into metal, but most are cut into lacquer-coated metal.

This post has been edited by pdq: Mar 5 2008, 20:25
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Woodinville
post Mar 5 2008, 20:03
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QUOTE (pdq @ Mar 5 2008, 10:27) *
QUOTE (Axon @ Mar 5 2008, 13:39) *

But the contact area of the stylus covers many thousands of molecules, and PVC deforms elastically. So the actual traced waveform could have a resolution that is considerably more accurate than that implied by the size of a "single" PVC molecule, at the expense of some time resolution (which due to tracing distortion really isn't there anyway).

What exactly is a "single" PVC molecule, anyway? PVC is a chain polymer. It might be 100000A on its long axis, but each member of the chain is what, H3C2Cl? That can't be more than 50A. So even ignoring the contact area argument, you may be off by a few orders of magnitude on the size calculations.

I'm all for bashing vinyl, and I agree that you're unlikely to get more than 12 bits out, but I think this math is too sloppy to support that.

PVC consists of alternating CH2 and CHCl units, so in theory when cutting through the vinyl molecule you could cut to this small a unit by severing the molecule at a C-C bond. In reality none of this matters because the cutting is actually done on a metal master and not the vinyl.


And the vinyl is pressed, not cut.

The metal master is not cut, either, the lacquer is cut, then plated, and then the plated master is cast, and turned into a stamper, and then that presses the actual vinyl.

While I'm not a huge fan of LP either, the OP is actually too dismissive, but only a little. Left out is surface noise (it's a physics thing, you have to have it), elastic deformation, plastic deformation, mistracking, the effects of equalization ...


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SoAnIs
post Mar 6 2008, 03:13
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True, I simplified a lot. But, as I also showed, even if you could get it down to angstrom resolution you would still only have the equivalent of 19 bit audio. I ignored surface noise and such because it made the calculation easier, not because it was accurate. Since it makes things less accurate my calculations make it seem a bit better than it is.

The real point is that, physically, there is no such thing as analog. You can't (easily) move less than 1 atom, you can't detect changes that small with a needle (well, a STM can, but that's a very different needle) and thus digital truly can be equivalent to vinyl. Everything is quantized, so with enough bits of data stored anything can be accurately digitized up to the point where the uncertainty principle begins to matter.

That said, vinyl has big album art. NIN recently offered some good extras with their newest album, but I'm waiting for more artists to offer digital downloads + shipping you a poster/lyrics book/etc instead of trying to cram it into a CD jewel case.
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Vitecs
post Mar 6 2008, 08:46
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QUOTE (SoAnIs @ Mar 5 2008, 20:13) *
The real point is that, physically, there is no such thing as analog. You can't (easily) move less than 1 atom, you can't detect changes that small with a needle

To be correct, needle movement is analog. Medium is not, but if we think of tracking needle, not groove per se. So we're always end up with interpolation here when decreasing time delta to get to the "fraction" of molecula.
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tgoose
post Mar 6 2008, 11:12
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QUOTE (Vitecs @ Mar 6 2008, 07:46) *
QUOTE (SoAnIs @ Mar 5 2008, 20:13) *
The real point is that, physically, there is no such thing as analog. You can't (easily) move less than 1 atom, you can't detect changes that small with a needle

To be correct, needle movement is analog. Medium is not, but if we think of tracking needle, not groove per se. So we're always end up with interpolation here when decreasing time delta to get to the "fraction" of molecula.

Well OK, but that's no different in result to the reconstruction filter in a DAC; it's still using "quantised" information to create a smoothed out signal.
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SebastianG
post Mar 6 2008, 15:31
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Hello, SoAnIs!

There's one point I'm missing here. The signal coded on a vinyl disc is time-continous and not time-discrete. That means that any "molecule error" spreads over a very large frequency range. The audible band is only a small subset of it. So, without the knowledge about the noise's PSD it's difficult to estimate the signal-to-noise ratio you'll get after filtering out everything above 20 kHz.

Still, it's a fun thought experiment. smile.gif

Cheers,
SG
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A Dawg
post Jun 3 2008, 04:58
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QUOTE (SoAnIs @ Mar 5 2008, 03:20) *
24-bit precision gives you about 16.77 million values. Assuming a total groove width of 50 x 10^-6m, the maximum movement of the cutter is physically bounded at about half that. Much more and the cutter will be in the space for an adjacent groove. Thus, 50 microns width divided by 16.77 million gives us about 3 x 10^-12m, i.e. ~0.03 angstroms.

The diameter of a hydrogen atom is 1.0 angstroms (1 x 10^-10m). That would make the resolution of a 24-bit digital signal equivalent to an analog cutter whose resolution is just about 1/30 the width of a hydrogen atom. Sadly, this seems to be physically impossible, as none of the particles smaller than atoms are stable enough to be used in records.

Of course, records aren't made of hydrogen, they're made of the polymer pvc. One molecule of pvc is about 100,000 angstroms. This means that, if the cutters were actually removing single pvc molecules the vinyl records would have about 11 bits of resolution. Sadly, they don't get even that precise, though I'm not sure the actual precision. To get down to a record made of hydrogen atoms (possible under very low temp/very high pressure I suppose) one would need 19 bits. Anything beyond that is useless as long as the laws of physics hold.

Therefore, all other things being equal, digital is superior to vinyl. That said, mastering on CDs is often terrible while the mastering on records is often made somewhat better. This varies from CD to CD and record to record, and CDs are technologically far superior to records.



As far as I know there are an an infinite amount of numbers between the number 1 and the number 2. But I guess you could measure the amount of pixels in film if you measured each ray of light.


If you are recording digitally the the bit depth would measure how high or low the wave is at any given sample. 16 bit, if I am not mistake, only has 9 values in either direction. What I don't understand is why people think 9 is good enough to say any more is a waste.
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saratoga
post Jun 3 2008, 06:10
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QUOTE (A Dawg @ Jun 2 2008, 23:58) *
As far as I know there are an an infinite amount of numbers between the number 1 and the number 2. But I guess you could measure the amount of pixels in film if you measured each ray of light.


Depends on the set of numbers you're operating with.

QUOTE (A Dawg @ Jun 2 2008, 23:58) *
If you are recording digitally the the bit depth would measure how high or low the wave is at any given sample. 16 bit, if I am not mistake, only has 9 values in either direction. What I don't understand is why people think 9 is good enough to say any more is a waste.


2^16 = 65536, so yes, you are mistaken. 18 total values would be just past 4 bits, which is obviously insufficient.
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A Dawg
post Jun 3 2008, 06:41
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I personally feel that 16 to 24 bit is a small, but noticeable step up. I have a soundcard which lets me change the bit depth while music is playing. I have played around with it and I would say that it was about as noticeable as going from 720p to 1080p on a 35 inch tv. Few would notice. But at close glance, you can see the extra detail. But when you go from 44.1k to 48k BIG difference. Most noticeable when a quiet passage is played at a high volume. CD's suffer a digital hiss, which are basically the steps in between samples. DVDs sound clearer than cd's to me because of these extra "steps." More steps in the same amount of space = smaller step. But the sound is of a lower quality than a cd, if that even makes sense. I am not very good at expressing my thoughts through words sometimes :'(. And I was joking about the lower.


Here is my stance. I am a guy who still buys records and loves to flac em 96k times a second with 24 bits in them samples. You could have the normal 1(16 bit) lock on your doorknob. But I have a deadbolt, locking knob, and a chain.(24 bit) And instead of a wooden or plastic (44.1 khtz)door, I have a steel door.

Am I actually safer(sound better) than you just because of that, maybe. But I definitely feel safer.

Was that too dumb sad.gif
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Axon
post Jun 3 2008, 08:34
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I would argue that a closer analogy than a wood door vs. a steel door would be going vegetarian because you're afraid of food poisoning. Just because you feel safer about it doesn't mean you really are safer, or that the risk was all that important in the first place.

You should read up more on sampling theory. There is no "space" between samples.

DVDs are usually lossily encoded on their audio tracks, but their DACs are generally of the same garden variety that are used in computers. There's no difference in how they decode audio - merely in the choice of lossy encoder used.

That said, I still rip vinyl to 24/96, but I make no justification for it nowadays, and I'm running low enough on disk space that I am considering switching to 16/44 for good.
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2Bdecided
post Jun 3 2008, 10:16
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QUOTE (A Dawg @ Jun 3 2008, 06:41) *
I personally feel that 16 to 24 bit is a small, but noticeable step up. I have a soundcard which lets me change the bit depth while music is playing. I have played around with it and I would say that it was about as noticeable as going from 720p to 1080p on a 35 inch tv.
I'll tell you why that's a terrible analogy - if the TV can actually display 1920x1080 native resolution, and the source image is sharp at that pixel level, then anyone with reasonable eye sight, sat close enough to the TV, will be able to see a difference very easily as you switch from one to the other on a still picture. Passing an ABX test would be absolutely trivial.

Whereas, with all other things being equal, in a correctly controlled blind test, passing an ABX test of 16 vx 24 bits, or 44.1kHZ vx 48kHz is near impossible, except with extreme samples and/or faulty equipment.

Cheers,
David.
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tot
post Jun 3 2008, 12:15
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QUOTE (Axon @ Jun 3 2008, 09:34) *
That said, I still rip vinyl to 24/96, but I make no justification for it nowadays, and I'm running low enough on disk space that I am considering switching to 16/44 for good.


I have always felt that 16 bits reproduces the vinyl's surface noise quite well so 24 bits would be overkill, at least for final playback. For recording 24 bits is better if any manipulation will be done to have more data to work with.


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Roseval
post Jun 3 2008, 12:20
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Some calculations for you and a proof that the LP has a resolution of 32000 bits!
http://www.st-andrews.ac.uk/~www_pa/Scots_...rt12/page2.html


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Slipstreem
post Jun 3 2008, 12:57
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From the article...
QUOTE
The effect is to divide the microns swing of a 0 dB 1 kHz sinewave into 32,000 steps...
Steps, not bits. That's slightly less than 15 bits. That equates to 1600 steps (less than 11 bits) at 20kHz. biggrin.gif

Cheers, Slipstreem. cool.gif
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2tec
post Jun 3 2008, 16:10
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QUOTE (SoAnIs @ Mar 5 2008, 03:20) *
Therefore, all other things being equal, digital is superior to vinyl. That said, mastering on CDs is often terrible while the mastering on records is often made somewhat better. This varies from CD to CD and record to record, and CDs are technologically far superior to records.

Sure, in theory. Thankfully, music reproduction depends on many factors, of which bit depth plays only a small part. From my perspective it seems clear that the analog versus digital methodology argument is logically moot. People are simply comparing apples to oranges. Personally, I believe that analog music reproduction has its place, as does digital music reproduction. These two distinct methods are clearly not in any way equal, and personally I believe, not even comparable. Why people waste their time going on about which is better is simply beyond me!

Here, let me try using an example of what I'm trying to get at; which is better, an apple or an orange? Boy doesn't that answer sound obvious! Now, lets reword it; which is better, analog or digital? See, just as silly, in my humble opinion of course. tongue.gif

This post has been edited by 2tec: Jun 3 2008, 16:40


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2Bdecided
post Jun 3 2008, 18:04
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But a digital recording can sound like anything you want - including an exact and perfect reproduction of the sound of an analogue (vinyl) recording, including all the noise, distortion, clicks, pops etc.

A vinyl recording will only sound like digital when the content is such that all the faults are masked. In other words, you can listen to a digital recording and think you're listening to vinyl; but you can't listen to vinyl and think you're listening to digital.

Therefore digital is superior as a delivery format because it's doesn't impose its own character on the audio. "Special effects" should be added because people want to, not because they're part of the delivery format.

Cheers,
David.
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Juha
post Jun 3 2008, 19:05
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QUOTE (tot @ Jun 3 2008, 14:15) *
QUOTE (Axon @ Jun 3 2008, 09:34) *

That said, I still rip vinyl to 24/96, but I make no justification for it nowadays, and I'm running low enough on disk space that I am considering switching to 16/44 for good.


I have always felt that 16 bits reproduces the vinyl's surface noise quite well so 24 bits would be overkill, at least for final playback. For recording 24 bits is better if any manipulation will be done to have more data to work with.



I'm using a 36dB/oct HP filter for to get these noises off from vinyl recordings. Actually I even use a software based RIAA filter so that's why 24-bit is my choice.




Juha
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Axon
post Jun 3 2008, 20:20
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Oh, nice! Another flat transfer partisan. Welcome to the club.
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