The compact disk, its demise(?) and classical music

[Archaic Torso of Apollo]

And however comforting or reassuring CDs may seem, they are not necessarily permanent either, what with bronzing and things like that.

Wasn't "bronzing" a problem with only one CD pressing plant, and then only for a few years? That's what I seem to remember.

I've probably bought more than 1000 CDs over the years, and had problems with only a handful of them.

[Spineur]

Yes CD deteriorate with time.  The laser burned one last at most 6 years.  The pressed one fare better.  I did a micrography  of a CD from the eighties and you can see the aging.  My gess is their live expectancies is around 30 years.

The other problem of the CD is the sound quality which is good but not of the concert Hall level.  After attending a concert, I often put on a CD of a piece I just heared when I get home.  In some cases the letdown is immense.  In all fairness a lot has to do with the engineering of studio recording, which wasnt so hot in the eighties.

[Andante]

Yes I had a few that had to be replaced due to bronzing but today one expects the odd glitch. Even if you put all your music onto HD it can be lost so you have to back up, but how many of you backup your backup.

[XB-70 Valkyrie]

I did a micrography  of a CD from the eighties and you can see the aging.  My gess is their live expectancies is around 30 years.
...

Are you a microscopist? What did you use--SEM? AFM? Here is some of my work: www.kevinjcarpenter.com

[Andante]

Yes CD deteriorate with time.  The laser burned one last at most 6 years.  The pressed one fare better.  I did a micrography  of a CD from the eighties and you can see the aging.  My gess is their live expectancies is around 30 years

So much for a "life time" is it just the material used that deteriorates or some thing in the manufacturing?

[71 dB]

My gess is their live expectancies is around 30 years.

So CDs made before 1986 should not work anymore?
I'd say CDs play fine for 100 years if you live that long yourself and handle them with care.

[71 dB]

Yes CD deteriorate with time.  The laser burned one last at most 6 years. 

I burned my first CD-R discs almost 20 years ago and they still seem to work (error correction can handle them).

The other problem of the CD is the sound quality which is good but not of the concert Hall level.  After attending a concert, I often put on a CD of a piece I just heared when I get home.  In some cases the letdown is immense.  In all fairness a lot has to do with the engineering of studio recording, which wasnt so hot in the eighties.

Technical quality and recording quality are different things. Technically CD is "Concert Hall level" if that's even possible. Many hifi sets aren't.

[Andante]

Technically CD is "Concert Hall level" if that's even possible. Many hifi sets aren't.

I thought CD quality was a compromise that enabled a CD to store a full one hours + of music.

[(poco) Sforzando]

Yes CD deteriorate with time.  The laser burned one last at most 6 years.  The pressed one fare better.  I did a micrography  of a CD from the eighties and you can see the aging.  My gess is their live expectancies is around 30 years.

The other problem of the CD is the sound quality which is good but not of the concert Hall level.  After attending a concert, I often put on a CD of a piece I just heared when I get home.  In some cases the letdown is immense.  In all fairness a lot has to do with the engineering of studio recording, which wasnt so hot in the eighties.

My understanding is that the 80 minute length of a 640Mb CD came about because some early engineer wanted to fit all of Schmidt-Isserstedt's Beethoven's 9th on one small disc. But the problem is that as a result the sampling rate for CDs had to be compromised. Of course CD's are not at concert hall level, because some of the subtler overtones are lost. If you hear music only or mostly on CD and have never been inside an acoustically splendid hall, then you really are not hearing the full bloom of the instruments. And while there have been SACDs with greater capacity and supposedly improved sampling rate, the degree of improvement has been disputed and the huge wave of LP-CD conversions in the 1980s-going forward have not been retrofitted to the entire catalogue. And who would buy them?

This is unlike what's happened in home versions of film, where a company like Criterion originally issued DVDs that were sometimes quite poor, and slowly the company has been reissuing and remastering its catalogue to take advantage of the new BluRay format that can hold a far greater amount of digital information in the same space. Even so, the company can issue maybe 30 films a year.

[Scion7]

They used to say VHS had a 10 yr lifespan before turning to static.  Not!

They said all laserdiscs would rot.  Not!

With proper care those CD's will outlast your grandchildren.

[Daverz]

My understanding is that the 80 minute length of a 640Mb CD came about because some early engineer wanted to fit all of Schmidt-Isserstedt's Beethoven's 9th on one small disc. But the problem is that as a result the sampling rate for CDs had to be compromised. Of course CD's are not at concert hall level, because some of the subtler overtones are lost.

See https://en.wikipedia.org/wiki/44,100_Hz

From my own (not very extensive) listening tests, I can't tell the difference between 44.1/16,  96/24 and 192/24 files in my stereo system.  It certainly doesn't make the difference between concert hall level and not.  I think the 44.1k and 16-bit depth are entirely adequate.

[Archaic Torso of Apollo]

And while there have been SACDs with greater capacity and supposedly improved sampling rate, the degree of improvement has been disputed and the huge wave of LP-CD conversions in the 1980s-going forward have not been retrofitted to the entire catalogue. And who would buy them?

I went to my local audio hi-end store a couple years ago and asked for an SACD demo. They said I shouldn't bother because it was a dying format.

My listening room in any case is never going to be an "acoustically splendid hall" so I understand that certain compromises have to be made.

[Andante]

See https://en.wikipedia.org/wiki/44,100_Hz

From my own (not very extensive) listening tests, I can't tell the difference between 44.1/16,  96/24 and 192/24 files in my stereo system.  It certainly doesn't make the difference between concert hall level and not.  I think the 44.1k and 16-bit depth are entirely adequate.

It does depend on how good you system is, 10 years ago I could easily tell the difference between between a normal CD and one made @ mp3 standard 192, 256 even 320 at times, but with age I struggle to find a difference.

[Parsifal]

My understanding is that the 80 minute length of a 640Mb CD came about because some early engineer wanted to fit all of Schmidt-Isserstedt's Beethoven's 9th on one small disc. But the problem is that as a result the sampling rate for CDs had to be compromised. Of course CD's are not at concert hall level, because some of the subtler overtones are lost. If you hear music only or mostly on CD and have never been inside an acoustically splendid hall, then you really are not hearing the full bloom of the instruments. And while there have been SACDs with greater capacity and supposedly improved sampling rate, the degree of improvement has been disputed and the huge wave of LP-CD conversions in the 1980s-going forward have not been retrofitted to the entire catalogue. And who would buy them?

This is unlike what's happened in home versions of film, where a company like Criterion originally issued DVDs that were sometimes quite poor, and slowly the company has been reissuing and remastering its catalogue to take advantage of the new BluRay format that can hold a far greater amount of digital information in the same space. Even so, the company can issue maybe 30 films a year.

To obsess over the CD is to focus on the wrong link in the signal chain. You have a microphone that turns sound pressure levels into a voltage on a wire, then a bunch of electronics that transfer that voltage to a loudspeaker or headphone transducer, with the voltage and current scaled up to produce enough sound power. Then a bunch of magnets, coils and cones made of cardboard or other more exotic materials to convert that voltage into sound waves in your room. With modern electronics that voltage being supplied to the speakers can be made virtually identical to the original microphone signal (if, of course, the producer does not deliberately tamper with it). The lack of realism in recorded music comes form the limitations of the microphones, loudspeakers and listening rooms. Put the same signal into two sets of audiophile headphones, or audiophile speakers and you will find that sound pressure levels recorded by test equipment are dramatically different. The same goes for the signals produced by two professional microphones placed in the same sound field.  The limitations of the transducers dwarf any difference between the original signal and the CD player's approximation of it.

[Parsifal]

See https://en.wikipedia.org/wiki/44,100_Hz

From my own (not very extensive) listening tests, I can't tell the difference between 44.1/16,  96/24 and 192/24 files in my stereo system.  It certainly doesn't make the difference between concert hall level and not.  I think the 44.1k and 16-bit depth are entirely adequate.

I generally agree.

There is an issue is that with 44.1kHz sampling. The maximum signal that can be represented is 22.05 kHz. Some will claim to hear beyond 22 kHz, but very few can. The main issue is that any frequency component above 22.05 kHz gets "aliased" to a frequency below 22.05 kHz. If there is signal at 40 kHz in the audio feed it gets aliased to 44.1 kHz - 40 kHz = 4.1 kHz by the digital recorder. That is a horrible form of distortion and the early recorders needed brick-wall filters to cut off any signal above 22 kHz. The filters themselves could distort the sound.

Modern recorders sample very fast (192 kHz or faster) and the spurious frequencies can be suppressed by mathematical processing of the signal as it is converted to 44.1 kHz sampling, eliminating the need for the agressive analog filters.

80's digital sound often gets criticized, and I think part of the problem is that the sound engineers of the day had developed their bag of tricks to compensate for the weakness of analog recording equipment, and this was not appropriate for digital recorders, which had different limitations.

[The new erato]

See https://en.wikipedia.org/wiki/44,100_Hz

From my own (not very extensive) listening tests, I can't tell the difference between 44.1/16,  96/24 and 192/24 files in my stereo system.  It certainly doesn't make the difference between concert hall level and not.  I think the 44.1k and 16-bit depth are entirely adequate.

Neither can I. The effective bandwidth and signal/noise ratio of a CD is larger than that of an LP. Any perceived differences between concert hall, CD and LP (and I'm not saying there aren't) has little to do with bandwidth and signal/noise ratio, that's for sure. I agree with Scarpia here. Also Daverz is onto something with his mention of distortion structure. I believe distortion components, though extremely low in digital media, can explain some differences. LPs (and tubes) distort like hell, bur with a very "natural"  distribution of distortion components.

That said, I will never exchange the convenience and lack of background noise of digital media and transistors for LPs and tubes-

[Daverz]

I went to my local audio hi-end store a couple years ago and asked for an SACD demo. They said I shouldn't bother because it was a dying format.

It seems to be still hanging on for classical releases.

[Jo498]

Now there are three different things being discussed in the thread. Originally it was about the vaning of the CD as the standard medium of music. While fully underway, especially in the popular sector, it seems likely that CD will stick around for a while because there are many people who prefer physical media, especially as gifts...

The second question is whether the quality offered by the CD is sufficient. While there have by now been media with higher resolution around for several years (SACD, DVD-A) they remained restricted to niches and lossy downloads seemed a larger threat than *better* physical media. Of course, one can in principle with good infrastructure combine both "threats" and offer, as e.g. Linn does, lossless downloads in "studio quality! (higher sampling rate etc.). None of these higher quality options seems to have become mainstream or be likely to do so, I think. But their existence is also an indicator that there are listeners beyond those perfectly happy with lossy mp3s.

Another different point is the durability of actual already existing CDs. This is, among other things, important for the *use value* of our collections and the feasibility of a used market should CDs become obsolete.

I would be interested in what Spineur "saw" when he investigated older CDs. I think that an average lifetime of 30 years is almost certainly wrong. Unless it is a very narrowly peaked distribution collectors would have encountered hundreds of unplayable discs from before ca. 1990 and many from the mid/late 1990s would be unplayable. Even if narrow around 30 years, there are still lots of CDs around from 1983-87 that are perfectly playable. In fact, I think I have encountered among thousands of discs maybe two that were "mysteriously faulty", i.e. apart from obviously bronzed or deeply scratched ones.
I'd be willing to bet at least 3:1 that a disc from 1986 with no visible scratches or faults (like bronze discoloration) will play perfectly well. And even those with lots of visible scratches are usually playable, if these scratches are not too long or too deep. Not to mention that scratches are usually due to obviously not treating discs well.
So I am pretty sure we have not even reached the typical or average lifetime of a CD manufactured in 1985 or so.
Still, I hope to live for at least another 30 years (I dare to hope for another 50, if I beat my granddad...) and hopefully be listening to CDs in 2050. Therefore the lifetime estimation is relevant, even if it's 50 years or more.

[Spineur]

Are you a microscopist? What did you use--SEM? AFM? Here is some of my work: www.kevinjcarpenter.com

Professional physicist (nanosciences).  I did a deep UV image.  Cant use SEM because the top plastic layer charge.  I'll try to find the picture for you.

Over long period of time there is atomic diffusion.  The main issue comes from the choice of aluminium for the metallic layer.  This metal likes to ball up, and the diffusion which is at the nanometer level turns into a change of morphology of the film and this alters the reflectivity a great deal.
By the way, the magnetization in hard disks decays also over similar period of time, and the charge trapped in SD memories diffuse also.

My experience is that no format, not even DSD 128, matches the concert Hall experience.  This turns out to be fortunate otherwise we wouldnt go to concert so often.  I can quite clearly hear (and measure) the difference between 16bits/44kHz and the 24/96kHz which is at present the new standard.  The difference between DSD and PCM format is less obvious to me.  There is a new DXD format out which uses 32 bits.  The claim is you can really hear a note dying into silence with it.
Anyway, I can still live with the CD standard, but in the same way the industry went from DVD to blu ray, there will be an upgrade to a new format (PCM or DSD).  Its going to take a lot more time because the industry is in poor shape, and also because several generations have gotten used to compressed music, the degree zero of music quality.

[71 dB]

I thought CD quality was a compromise that enabled a CD to store a full one hours + of music.

This is a thing that can be easily misunderstood. This is complicated, but I try to explain this. The sample rate 44100 Hz and dynamic depth of 16 bits are pretty much the minimum in order to have "compromised full quality" in late 70's/80's technology. Today digital technology is much more advanced and 44100 Hz/16 bit audio is not as compromised it used to be decades ago.

Reconstruction filter
DACs must reconstruct the original signal from the samples stored on the disc. By the way, theoretically this can be done perfectly within the limitations of dynamic range, something a lot of people don't understand. So, theoretically we can have the original signal plus noise at quantization level + dither noise in order to avoid granulation. The only requirement is that we don't have frequencies above 20000 Hz (theoretically half of the sampling frequency = nyquist frequency = 22050 Hz). Anyway, DACs must reconstruct the original signal from the samples and this involves reconstruction filtering. This filter must be VERY deep between the narrow frequency band 20000 - 22050 Hz in order to block frequencies above nyquist frequency and pass frequencies below 20000 Hz. Back in the 80's this was tricky. Oversampling makes things easier. Two times oversampling means our new sampling frequency is 88200 Hz and the new nyquist frequency is 44100 Hz meaning the reconstruction filter can fall down between 20000 Hz and 44100 Hz.

Back in the days it would have been easier to reach great sound quality with a bit higher sampling frequency so in that sense 44100 Hz was a compromise. Today, digital technology has developped so much we can use all the potential of the 44100 Hz/16 bit audio and luckily it is just good enough for human hearing. Higher sampling rates (96 kHz, 192 kHz...) and bit depths (24) just makes many think CD is "lacking". What CD is lacking is multichannel audio and that's it.