Blu-spec

[FideLeo]

What is the new blu spec thing about?

I think it's a Japan-only thing to this point.  In-house remastering and remixing
may or may not have been involved but there is supposedly a real, if quite subtle, audible
difference from all previous versions of the same recording.  Not just Sony-BMG, but Denon
and Universal Japan have also come up with their patent "technology": blu-spec
(better cut cd masters using blue-ray laser); HQ-cd (clearer plastic and a new alloy for
the reflective layer); SHM-CD (similar to HQ-cd, featuring enhanced transparency
polycarbonate material developed for use in LCD screens).  



This blu-spec reissue of L'Archibudelli K563 that I tried compares well with the other
2 pressings that I have of this recording (one from the Bijsma anniversary box).  I think I do
perceive differences which I would call an improvement in instrumental textures and overall
clarity of details.  Whether this holds true for all will, of course, depend on one's
equipment, environment, mood and/or ears.     Worth a try if they happen to
put out some recording that you feel has great sentimental values (such as this Mozart
for me -- I think it was my first chamber recording from these musicians; my first recording
of this music, recorded by "Members of Amadeus QT for DG," may have never made it to
the CD era).

[Scarpia]

I think it's a Japan-only thing to this point.  In-house remastering and remixing
may or may not have been involved but there is often a real, if quite subtle, audible
difference to previous versions of the same recording.  Not just Sony-BMG, but Denon
and Universal Japan have also come up with their patent "technology": blu-spec
(better cut cd masters using blue-ray laser); HQ-cd (clearer plastic and a new alloy for
the reflective layer); SHM-CD (similar to HQ-cd, featuring enhanced transparency
polycarbonate material developed for use in LCD screen).  

This blu-spec reissue that I tried compares well with the other 2 pressings that I have
of the same recording (one from the Bijsma anniversary box).  I think I do hear
differences which I would call an improvement in instrumental textures and overall
clarity of details.  Whether this holds true for all will, of course, depend on one's
equipment, environment, mood and/or ears.     Worth a try if there happens to
be some recording that they put out which you feel has great sentimental values
(like this Mozart disc to me).

It is very difficult to arrive at a mechanism by which "blue-spec" and HQ-cd could make any difference whatsover.  Numbers are numbers, either your player reads them or it doesn't.  The claim that great care is needed to read a cd is often encountered, so once when I ended up with two copies of the same disc I read both of them into lossless wav files on my computer and compared them using a program that exhaustively compares them.  They were bit-for-bit identical.  Not a single bit misread in an entire CD.  If the cd is in good condition (no enormous scratches that make the player skip) there are simply no read errors to be improved upon.

[FideLeo]

It is very difficult to arrive at a mechanism by which "blue-spec" and HQ-cd could make any difference whatsover.  Numbers are numbers, either your player reads them or it doesn't.  The claim that great care is needed to read a cd is often encountered, so once when I ended up with two copies of the same disc I read both of them into lossless wav files on my computer and compared them using a program that exhaustively compares them.  They were bit-for-bit identical.  Not a single bit misread in an entire CD.  If the cd is in good condition (no enormous scratches that make the player skip) there are simply no read errors to be improved upon.

I have read a lot comments re blu-spec etc (some along the same line of reasoning as you put out above) even before I ordered the trial disc.  Well, speaking for myself only, I must say I am glad that I tried.  It could be that
Sony had actually touched up the recording, but of course they will never own up to the fact if they did.

[Scarpia]

I have read a lot comments re blu-spec etc (some along the same line of reasoning as you put out above) even before I ordered the trial disc.  Well, speaking for myself only, I must say I am glad that I tried.

It is quite possible that the recording was remastered when the blu-spec was released, but if they are the same master, the same stream of numbers, how can they sound different?

[FideLeo]

It is quite possible that the recording was remastered when the blu-spec was released, but if they are the same master, the same stream of numbers, how can they sound different?

Denon's HQCD page (In Japanese) actually quotes the reissue producer saying that they have re-mastered the recordings slated for HQCD reissues, as recordings made in early 1990's and before somehow sound "thin" to the team and demand a "re-scan" or a new "balance."  My reckoning is that Sony may have done the same (remastering) but attributes all differences to their new "technology."  Perhaps truth beyond mere shoptalk will be known when other music companies actually take up Sony's offer and try out the blu-spec gimmick for themselves.

edit.  I just did a bit of 'blu-spec' digging on the net and encountered this description of an audit of blu-spec disc listened side by side with a previous remaster of the same material.  "On the loudpeakers, the original remastered CD sounded louder and a bit harsher (but OK) compared to the Blu-spec.  The high end seems reined in a bit on Blu Spec and one can assume when that happens you can hear the finer details in between." (http://unofficialjefflynne.blogspot.com/2009/01/blu-spec-discovery.html)  This author, Jeff Lynne, was listening to a popular music title performed by ELO, and yet what he found actually matches what I had in mind as well when I listened to the Mozart trio recording.  The fortes are less shouty, and the pianos are more clearly etched against a slightly quieter background.  While he obtained these results on a blue-ray dvd player, I was only using a modest Pioneer dvd deck for my audit. 

[Fëanor]

It is very difficult to arrive at a mechanism by which "blue-spec" and HQ-cd could make any difference whatsover.  Numbers are numbers, either your player reads them or it doesn't.  The claim that great care is needed to read a cd is often encountered, so once when I ended up with two copies of the same disc I read both of them into lossless wav files on my computer and compared them using a program that exhaustively compares them.  They were bit-for-bit identical.  Not a single bit misread in an entire CD.  If the cd is in good condition (no enormous scratches that make the player skip) there are simply no read errors to be improved upon.

This pretty much the way I see it.  Blu-spec might produce more perfect pits on the CD surface but so what?  We are speaking of a digital medium: the pits don't have to be perfect -- the idea physical perfection of the medium is an analog concept that doesn't necessarily apply in digital.  The fact is the pits only have to be good enough.

Nevertheless there are arguments why a blu-spec disc might sound different, at least under some conditions.  Perhaps the most plausible of these is that, playing the disc in real time in a given CD player, the blu-spec will (1) permit fewer read errors (requiring less error compensation by the CD player), and/or (2) results in less "jitter".  Jitter is timing errors in the delivery of the bits to the DAC even while the bits themselves are all there and correct.  (Jitter is the currently the favourite real or imagined difference maker for many hardcore audiophiles who, of course, hear sound differences between absolutely everything.)

But let's remember that ripping a CD with a computer is a rather different process from playing the CD in real time on a CD player.  Most importantly the electronics of computer optical drive have stronger error detection, and much stronger error correction capabilities the typical CP player, especially if programs such as EAC or dBpoweramp are used for the rip.  WAV (or lossless) files resulting from the rip of standard CD and blu-spec might be bit-indentical, but this doesn't mean that the CD play would see indentical bits.

Bit-identical files, played from the computer, ought to sound the same.  But then the hardcore audiophiles are good at coming up with reason why to bit-identical files might sound different, e.g. file fragmentation on the hard disk.  I happen to believe these arguments are bogus in actuality. In any case, they have nothing to do with blu-spec sounding better than bit-identical file from a standard CD.

[FideLeo]

I happen to believe these arguments are bogus in actuality. In any case, they have nothing to do with blu-spec sounding better than bit-identical file from a standard CD.

Indeed jitter and noises generated from excessive error-correction were the two reasons cited by Sony as to why their blu-spec discs may just sound better even as bit-identical files.

http://www.homecinemachoice.com/features/blu-spec+CD+sounds+better

[Scarpia]

Nevertheless there are arguments why a blu-spec disc might sound different, at least under some conditions.  Perhaps the most plausible of these is that, playing the disc in real time in a given CD player, the blu-spec will (1) permit fewer read errors (requiring less error compensation by the CD player), and/or (2) results in less "jitter".  Jitter is timing errors in the delivery of the bits to the DAC even while the bits themselves are all there and correct.  (Jitter is the currently the favourite real or imagined difference maker for many hardcore audiophiles who, of course, hear sound differences between absolutely everything.)

But let's remember that ripping a CD with a computer is a rather different process from playing the CD in real time on a CD player.  Most importantly the electronics of computer optical drive have stronger error detection, and much stronger error correction capabilities the typical CP player, especially if programs such as EAC or dBpoweramp are used for the rip.  WAV (or lossless) files resulting from the rip of standard CD and blu-spec might be bit-indentical, but this doesn't mean that the CD play would see indentical bits.

Bit-identical files, played from the computer, ought to sound the same.  But then the hardcore audiophiles are good at coming up with reason why to bit-identical files might sound different, e.g. file fragmentation on the hard disk.  I happen to believe these arguments are bogus in actuality. In any case, they have nothing to do with blu-spec sounding better than bit-identical file from a standard CD.

There is no physical mechanism for bit-jitter based on the disc quality.  Even a standard cd player is essentially a special purpose computer.  The data is read off the disc into a small memory buffer, the memory buffer is checked for integrity, error correction is done if necessary, then data is sent to the DAC.  The timing of this data going to the DAC is determined by the clocking of data out of memory, which is not tied to the read operation.

As for error rates, I don't have any strong argument, other than the one case where two discs read identical.  If 650 Mb can be read without a single bit error, how likely is it that the typical disc has significant read errors?  For the sound to be generally degraded, rather than having a little pop now and them, read errors would have to be pervasive.  It is true that CD-ROM data discs have more redundancy than CD music discs which would result in lower error rates.  However, when playing a CD music disc, I don't see any reason to believe a $19.99 CD reader in my computer would have an advantage over my $1000 CD player.  As I mentioned above, the CD player is essentially a special purpose computer programmed to do one thing, why couldn't they get it to work as well as a computer with a $19.99 CD-ROM reader?

[DavidW]

Thanks for the explanation and discussion of blu-spec cds Masolino and Scarpia.  It sounds like snake oil to me, but it's interesting to hear about it anyway.

[Fëanor]

There is no physical mechanism for bit-jitter based on the disc quality....

Some disagree including the Blu-spec sponsors.  For my part, I only say that I agree there is no reason to expect Blu-spec to sound better under normal circumstances based on its technical superiority.

[DavidRoss]

Some disagree including the Blu-spec sponsors.  For my part, I only say that I agree there is no reason to expect Blu-spec to sound better under normal circumstances based on its technical superiority.

The info provided by Masolino re. improvements in cutting precision, disc clarity, and reflective layer integrity all seem reasonably likely to reduce read errors.  Otherwise, given the same data files, the ones and zeroes would be the same and so qualitative differences in sound seem unlikely.  (But see: http://www.stereophile.com/reference/590jitter/.)  In short, to me the Blu-spec sounds as if it improves some measures of quality control in manufacturing (materials and process), thus might be expected to yield audible differences in cases where (a) manufacturing standards are notably inferior, resulting in problematic product, or (b) the disc transport/read/buffering system is prone to read errors and has trouble correcting them (pretty unlikely these days unless something's broken!).

Now playing:  Dvořák Symphony 8, Kubelik/BP -- Loved hearing the 7th yesterday, piqued my interest in hearing the 8th again and so far I'm loving their performance--energetic, invigorating, and yet gorgeous in repose, the beautiful tone of the winds and the tight precision of the strings are making me hear this piece anew--not sure I've ever really listened to Kubelik's 8th before!  He may just have the measure of this piece more to my liking than those I'm more accustomed to hearing (Kertész, Szell, Dohnányi).

[Scarpia]

The info provided by Masolino re. improvements in cutting precision, disc clarity, and reflective layer integrity all seem reasonably likely to reduce read errors.  Otherwise, given the same data files, the ones and zeroes would be the same and so qualitative differences in sound seem unlikely.  (But see: http://www.stereophile.com/reference/590jitter/.)  In short, to me the Blu-spec sounds as if it improves some measures of quality control in manufacturing (materials and process), thus might be expected to yield audible differences in cases where (a) manufacturing standards are notably inferior, resulting in problematic product, or (b) the disc transport/read/buffering system is prone to read errors and has trouble correcting them (pretty unlikely these days unless something's broken!).

That stereophile article contains some basic errors in its discussion of "bit jitter."  It correctly states that jitter in the timing of the DAC clock will compromise the quality of the output.  It also correctly states that jitter in the signal coming from the read head will cause data deterioration.  But it incorrectly assumes that these are connected.  The DAC clock is produced by an independent oscillator that clocks data from internal memory to the DAC.  Timing jitter in the read process will simply cause the data on the disc to be read incorrectly, which may or may not be correctable depending on how much data is incorrect.  (It is impossible for data to be transmitted directly from the cd signal to the DAC because the conversion process involves reading of redundant data which is compared with the main data and used to correct it if necessary.)

[DavidRoss]

That stereophile article contains some basic errors in its discussion of "bit jitter."  It correctly states that jitter in the timing of the DAC clock will compromise the quality of the output.  It also correctly states that jitter in the signal coming from the read head will cause data deterioration.  But it incorrectly assumes that these are connected.  The DAC clock is produced by an independent oscillator that clocks data from internal memory to the DAC.  Timing jitter in the read process will simply cause the data on the disc to be read incorrectly, which may or may not be correctable depending on how much data is incorrect.  (It is impossible for data to be transmitted directly from the cd signal to the DAC because the conversion process involves reading of redundant data which is compared with the main data and used to correct it if necessary.)

Huh?  I presume this is what you're referring to in Harley's article (Harley is a recording engineer and CD mastering engineer):

If jitter reaches the digital-to-analog converter, severe errors in the output analog signal result. Fig.6 shows how timing variations can affect the shape of an analog waveform. In theory, however, jitter is never allowed to reach the DAC: jitter-laden data are input to a buffer and clocked out with quartz-crystal accuracy to the DAC. Many engineers, including those at JVC who designed the K-2 Interface and digital designers at Madrigal Audio Laboratories, maintain that jitter can still reach the DAC, despite the buffering.

In researching the article, I had a fascinating discussion with Steve Taylor, Vice President and Director of Engineering at Madrigal, about digital audio in general and jitter in particular. He shared the results of research conducted at Madrigal by himself and Kevin Burke, Vice President of Research. They found a correlation between sonic performance and the quality of the HF signal read from a CD. The amount of jitter in the signal, as well as the shape and asymmetry of the HF signal, caused sonic changes when all other variables were kept constant. The circuitry that processes the HF signal before decoding can also affect the sonic character. Consequently, they developed a circuit that cleans up the HF signal before decoding.

Their research also confirmed that even the smallest amounts of jitter in the word clock that synchronizes the D/A converter affect the musicality of digital playback. A shift of as little as 100 picoseconds (0.1 nanoseconds, or 1/10 of a billionth of a second) in the word clock causes audible conversion-timing errors. These errors are more noticeable on high-frequency signals, and, significantly, low-level signals. A slight time shift (see fig.6) causes amplitude distortion. If a sample uses only a few bits, such as when quantizing a low-level signal, the error in relation to the signal is much greater than if the same error were applied to a high-amplitude sample. Jitter thus has a greater deleterious effect on low-level signal components (footnote 7). It is probably no coincidence that JVC's K-2 interface and high-quality CD transports—both of which reduce jitter—improve soundstage depth and low-level resolution, contributing to a sense of spaciousness.

If you take the time to read it carefully you will see your mistake.  Or is there some other section in Harley's 8500 word article where the claim you report is actually stated?

[Scarpia]

Huh?  I presume this is what you're referring to in Harley's article (Harley is a recording engineer and CD mastering engineer):
If you take the time to read it carefully you will see your mistake.  Or is there some other section in Harley's 8500 word article where the claim you report is actually stated?

I read it carefully, and this is the passage which I cannot agree with.  It is not possible to resolve this definitively without have a schematic diagram of the circuit to refer to, but I see no basis for the claim at the end of the first paragraph that jitter from the HF signal can affect the DAC despite buffering.  The Quartz oscillator that drives the DAC will inexorably give 44,100 equally spaced pulses (or some multiple thereof) per second to the DAC regardless of what is going on elsewhere in the circuit.  The DAC timing should be entirely determined by this signal Quartz oscillator signal.  If there is an effect, it can only be due to some design error, for instance, the error correction module consumes excessive current which overtaxes the power supply and causes the DAC to fail.  In this case they should be ashamed of themselves for designing a defective circuit.   I see vague claims in the second paragraph that the "sonic character" of the signal is affected by degradation of the HF signal, but I don't see that they claim to have done anything to eliminate the possibility that the degraded HF signal is simply causing read errors.  This is quite plausible but wouldn't have anything to do with jitter in the DAC. 

Ultimately I am not inclined to believe something for which a plausible physical mechanism can't be proposed.  If someone tells me that the bagels always taste better if you keep the windshield wipers on while driving home from the bagel store I'm going to be skeptical.  The real explanation will be that on rainy days the bagel chef tends to put more salt in, etc.

[DavidRoss]

I read it carefully, and this is the passage which I cannot agree with.  It is not possible to resolve this definitively without have a schematic diagram of the circuit to refer to, but I see no basis for the claim at the end of the first paragraph that jitter from the HF signal can affect the DAC despite buffering.  The Quartz oscillator that drives the DAC will inexorably give 44,100 equally spaced pulses (or some multiple thereof) per second to the DAC regardless of what is going on elsewhere in the circuit.  The DAC timing should be entirely determined by this signal Quartz oscillator signal.  If there is an effect, it can only be due to some design error, for instance, the error correction module consumes excessive current which overtaxes the power supply and causes the DAC to fail.  In this case they should be ashamed of themselves for designing a defective circuit.   I see vague claims in the second paragraph that the "sonic character" of the signal is affected by degradation of the HF signal, but I don't see that they claim to have done anything to eliminate the possibility that the degraded HF signal is simply causing read errors.  This is quite plausible but wouldn't have anything to do with jitter in the DAC. 

Ultimately I am not inclined to believe something for which a plausible physical mechanism can't be proposed.  If someone tells me that the bagels always taste better if you keep the windshield wipers on while driving home from the bagel store I'm going to be skeptical.  The real explanation will be that on rainy days the bagel chef tends to put more salt in, etc.

So if you read this carefully then you must see that Harley says nothing different, so you must have misread him in the first place.  However he does mention that other engineers disagree and presents a brief description of the experience of Madrigal engineers that found an effect that experiment suggests was transmitted from the original signal to the DAC, even though they could not precisely account for it.

You seem to be having trouble accepting empirical results because you haven't a theory that completely explains them.  Guess that means you don't believe in gravity, either.  Duh.

[Scarpia]

So if you read this carefully then you must see that Harley says nothing different, so you must have misread him in the first place.  However he does mention that other engineers disagree and presents a brief description of the experience of Madrigal engineers that found an effect that experiment suggests was transmitted from the original signal to the DAC, even though they could not precisely account for it.

You seem to be having trouble accepting empirical results because you haven't a theory that completely explains them.  Guess that means you don't believe in gravity, either.  Duh.

I have no criteria that empirical results must come with a theory that completely explains them.  I have a criteria that empirical results are suspect if they are self-inconsistent or inconsistent established laws of physics or logic.  I find the jitter argument is implausible because it implies communication between two parts of the circuit which are physically isolated from each other and only communicate through a well defined digital interface.  

And I bring to your attentioni the last sentence in the quote, in the paragraph where he talks about DAC jitter.

It is probably no coincidence that JVC's K-2 interface and high-quality CD transports—both of which reduce jitter—improve soundstage depth and low-level resolution, contributing to a sense of spaciousness.

Here he seems to endorse the idea that high quality CD transports which reduce HF jitter improve the signal, presumably by reducing DAC jitter, since that is what is being discussed in this paragraph.  I have no problem with the observation that removing HF jitter can improve reproduction, but the obvious mechanism is elimination of data errors, not by fixing DAC jitter, as this paragraph seems to imply.

[DavidRoss]

I have no criteria that empirical results must come with a theory that completely explains them.  I have a criteria that empirical results are suspect if they are self-inconsistent or inconsistent established laws of physics or logic.  I find the jitter argument is implausible because it implies communication between two parts of the circuit which are physically isolated from each other and only communicate through a well defined digital interface.  

And I bring to your attentioni the last sentence in the quote, in the paragraph where he talks about DAC jitter.

Here he seems to endorse the idea that high quality CD transports which reduce HF jitter improve the signal, presumably by reducing DAC jitter, since that is what is being discussed in this paragraph.  I have no problem with the observation that removing HF jitter can improve reproduction, but the obvious mechanism is elimination of data errors, not by fixing DAC jitter, as this paragraph seems to imply.

It implies no such thing.  You really need a remedial logic course, dude.

[Scarpia]

It implies no such thing.  You really need a remedial logic course, dude.

I don't see that childish insults are an appropriate answer to a civil discussion.

[Fëanor]

...
In short, to me the Blu-spec sounds as if it improves some measures of quality control in manufacturing (materials and process), thus might be expected to yield audible differences in cases where (a) manufacturing standards are notably inferior, resulting in problematic product, or (b) the disc transport/read/buffering system is prone to read errors and has trouble correcting them (pretty unlikely these days unless something's broken!).
...

While it's true that Blu-spec improve the physical perfect of the pits scribed onto the CD, what is highly doubtful that it will affect the sound with normal equipment.  Pits don't have to be "perfect" to work perfectly; they only have to be good enough.

It is a fact the CDs typically have very few errors whatever the cause.  This was evidenced to me using the EAC program that reports all errors found on a disk.  In my experience 0 - 3 minor errors are detected among the up to 700 MBs on a CD.

[DavidRoss]

It implies no such thing.  You really need a remedial logic course, dude.

I don't see that childish insults are an appropriate answer to a civil discussion.

This is further evidence of need for a remedial logic course.  The statement you're responding to was neither childish nor insulting, just a statement of fact apparent from your several failures to understand what you read.