I know the moderator just told us to stick to the topic, but since
the topic of green pens is related and has been discussed a lot
in this thread I hope he will not put me in the sin bin for this
one.
Over ten years ago, we were told to use a black felt tip pen on
the outer rim of the CDs, and there were even rubber or plastic
devices to attach to the rim. Now, recently, this seems to have
been rediscovered, but this time we are told to use a green
pen. Yes, green does absorb red very well, but black absorbs
all colours very well, and should absorb red at least as well
as green does. Have I misunderstood the idea of the green
pen? Otherwise, can anybody explain why green should be
better than black, except for the guy who is making money
from selling special green pens?
the topic of green pens is related and has been discussed a lot
in this thread I hope he will not put me in the sin bin for this
one.
Over ten years ago, we were told to use a black felt tip pen on
the outer rim of the CDs, and there were even rubber or plastic
devices to attach to the rim. Now, recently, this seems to have
been rediscovered, but this time we are told to use a green
pen. Yes, green does absorb red very well, but black absorbs
all colours very well, and should absorb red at least as well
as green does. Have I misunderstood the idea of the green
pen? Otherwise, can anybody explain why green should be
better than black, except for the guy who is making money
from selling special green pens?
maybe all of this "mods" "tweaks" "tricks" are only good for the guy who makes money with? Maybe these Audio magazines are some of those who are making money with publishing blue /green / ? / LED /pen / plastic disks Kokolores <=> snakeoil too? What should they publish else for people purchase theyr rubbish? They simply can´t write how a audio device sound, even if they try , like stereoplay or something like that just did, to put a CD into they re newspaper with" sound of different hifi - racks"
till,
Do you want one my favourites for the snake-oil candidate
shortlist? Take an old-fashioned 5.25" floppy disc. Use only the
actual magnetic disc and cut it down to the size of a CD. Put this
on top of the CD you are playing and it is claimed to improve the
sound. Furthermore, it is even claimed that it sounds better if
the floppy contains data, though nothing is said about what
data is best.
No, I have no intention to try this one, unless a very large
amount of people try it first and make the same claims. Then
I might take it under consideration.
This tweak is from the #1 swedish tweaker Josef Svalander
www.svalander.se (sorry, not much in english there). It should
be mentioned in his favour though that he labels this one as
a "bumble bee", by which he means something that cannot
work but does anyway. It should also be said that he does
provide many reasonable tweaks, which are usually taken
from other sources and being wide-spread on the net.
By the way, he has some articles on the effects of stray lights
affecting CD palying, the claimed superiority of black CDRs etc.
which is relevant to this thread, but it is only in swedish and
I suppose most of it has been published in one form or another
by other people before him.
Do you want one my favourites for the snake-oil candidate
shortlist? Take an old-fashioned 5.25" floppy disc. Use only the
actual magnetic disc and cut it down to the size of a CD. Put this
on top of the CD you are playing and it is claimed to improve the
sound. Furthermore, it is even claimed that it sounds better if
the floppy contains data, though nothing is said about what
data is best.
No, I have no intention to try this one, unless a very large
amount of people try it first and make the same claims. Then
I might take it under consideration.
This tweak is from the #1 swedish tweaker Josef Svalander
www.svalander.se (sorry, not much in english there). It should
be mentioned in his favour though that he labels this one as
a "bumble bee", by which he means something that cannot
work but does anyway. It should also be said that he does
provide many reasonable tweaks, which are usually taken
from other sources and being wide-spread on the net.
By the way, he has some articles on the effects of stray lights
affecting CD palying, the claimed superiority of black CDRs etc.
which is relevant to this thread, but it is only in swedish and
I suppose most of it has been published in one form or another
by other people before him.
The following quotes are from the posted Stereophile interview with Yves-Bernard Andre.
<i><b>Yes, it is quite interesting that in adding some noise to the signal, we can actually get more information back.</i></b>
This has absolutely no relevance to the playback of a CD. It is only relevant during the analog-to-digital conversion process where analog signal changes below the threshold of less than one half LSB would otherwise escape being digitally encoded.
The moment he analog signal has been encoded digitally, the amount of information that can exist in either the digital domain or any subsequent conversion back to analog has been fixed (carved in stone if you will) and there can be no subsequent adding to that information.
<i><b>No... it's optical noise. It permits the recovery of some information whose energy was not sufficient... To drive a zero to a one or the other way around? Exactly.</i></b>
Again, this has absolutely no relevance to the playback of a CD. And again, all of the information that can possibly exist on the CD or be subsequently extracted has already been fixed at the analog-to-digital conversion process.
Adding optical noise will only increase the electrical noise of the laser pickup's photodiodes which at best will have no effect at all and at worst, cause data errors.
And there is no tricking the system's error detection/correction system. The data is either read correctly with no errors, and if there are errors, they will either be corrected, interpolated, or the player will simply mute itself. Neither of which retrieves any addititional information.
<i><b>Let me explain it this way. You take a box of eggs and you "shake" it with a soundwave. But the energy is not totally sufficient that an egg moves from one hole to another. If you look, you have no signal, because the eggs are not moving. Then to add stochastic noise. The energy of this noise is sufficient to permit the egg to move from one hole to another. And at this time you don't see the noise, but you see the signal, which existed before.</i></b>
This is simply describing the effects of dither which is part and parcel of the analog-to-digital conversion process and yet again has absolutely no relevance to the playback of a CD.
Dithering allows the encoding of analog signal changes which are below one half LSB. When the noise is added to the signal, those analog signals below one half LSB now have a statistical probability (and that's how "stochastic" comes into this) of having their levels raised above one half LSB.
In other words, without dither, the probability of an analog signal change below one half LSB being encoded by the analog-to-digital process is zero. With dither, its probability is now that of the probability density function (pdf) of the dither noise.
What Yves-Bernard is talking about is what amounts to ex post facto dither, which is simply nonsense. Again, all of the information that can possibly exist on the disc was fixed at the time of analog-to-digital conversion and there is no way to retrieve anything additional.
Even if you were able to cause a random change in the LSB of the digital signal encoded on the disc, all you'd end up with is more noise. Not more signal.
And an LED doesn't know an LSB from a hole in the ground. If the optical noise were causing changes to the digital data, it would do it indiscriminately which would result in random changes of ALL of the bits, not just the LSB in which case your signal would simply be turned to noise.
<i><b>Here are two levels: the noise of the LSB, which is dither, and the noise we add with the blue laser in the analog domain.</i></b>
The only way the blue "laser" will add noise in the analog domain is to cause data errors in the digital domain. And it can't cause those errors discriminately JUST at the 1 LSB level. The data isn't even stored on the disc in such a fashion that the first LSB can be determined. Not to mention the fact that there is more than audio information on the disc.
Also, the LSB isn't just dither. It's also signal. Dither allows the encoding of signals well below the level of 1 LSB. As much as 10-20dB below 1 LSB.
<i><b>In the analog domain, you know, noise decreases slowly, continuously, so that even under the noise floor it is possible to retrieve some information. But with digital, under the LSB, there is no more information!</i></b>
This is incorrect. With dither, information FAR BELOW the LSB can be and is encoded. And every properly functioning analog-to-digital conversion system employs dither to do just that.
But even whether or not dither is applied during the analog-to-digital process, no amount of noise applied after the fact will retrieve any additional information.
se
<i><b>Yes, it is quite interesting that in adding some noise to the signal, we can actually get more information back.</i></b>
This has absolutely no relevance to the playback of a CD. It is only relevant during the analog-to-digital conversion process where analog signal changes below the threshold of less than one half LSB would otherwise escape being digitally encoded.
The moment he analog signal has been encoded digitally, the amount of information that can exist in either the digital domain or any subsequent conversion back to analog has been fixed (carved in stone if you will) and there can be no subsequent adding to that information.
<i><b>No... it's optical noise. It permits the recovery of some information whose energy was not sufficient... To drive a zero to a one or the other way around? Exactly.</i></b>
Again, this has absolutely no relevance to the playback of a CD. And again, all of the information that can possibly exist on the CD or be subsequently extracted has already been fixed at the analog-to-digital conversion process.
Adding optical noise will only increase the electrical noise of the laser pickup's photodiodes which at best will have no effect at all and at worst, cause data errors.
And there is no tricking the system's error detection/correction system. The data is either read correctly with no errors, and if there are errors, they will either be corrected, interpolated, or the player will simply mute itself. Neither of which retrieves any addititional information.
<i><b>Let me explain it this way. You take a box of eggs and you "shake" it with a soundwave. But the energy is not totally sufficient that an egg moves from one hole to another. If you look, you have no signal, because the eggs are not moving. Then to add stochastic noise. The energy of this noise is sufficient to permit the egg to move from one hole to another. And at this time you don't see the noise, but you see the signal, which existed before.</i></b>
This is simply describing the effects of dither which is part and parcel of the analog-to-digital conversion process and yet again has absolutely no relevance to the playback of a CD.
Dithering allows the encoding of analog signal changes which are below one half LSB. When the noise is added to the signal, those analog signals below one half LSB now have a statistical probability (and that's how "stochastic" comes into this) of having their levels raised above one half LSB.
In other words, without dither, the probability of an analog signal change below one half LSB being encoded by the analog-to-digital process is zero. With dither, its probability is now that of the probability density function (pdf) of the dither noise.
What Yves-Bernard is talking about is what amounts to ex post facto dither, which is simply nonsense. Again, all of the information that can possibly exist on the disc was fixed at the time of analog-to-digital conversion and there is no way to retrieve anything additional.
Even if you were able to cause a random change in the LSB of the digital signal encoded on the disc, all you'd end up with is more noise. Not more signal.
And an LED doesn't know an LSB from a hole in the ground. If the optical noise were causing changes to the digital data, it would do it indiscriminately which would result in random changes of ALL of the bits, not just the LSB in which case your signal would simply be turned to noise.
<i><b>Here are two levels: the noise of the LSB, which is dither, and the noise we add with the blue laser in the analog domain.</i></b>
The only way the blue "laser" will add noise in the analog domain is to cause data errors in the digital domain. And it can't cause those errors discriminately JUST at the 1 LSB level. The data isn't even stored on the disc in such a fashion that the first LSB can be determined. Not to mention the fact that there is more than audio information on the disc.
Also, the LSB isn't just dither. It's also signal. Dither allows the encoding of signals well below the level of 1 LSB. As much as 10-20dB below 1 LSB.
<i><b>In the analog domain, you know, noise decreases slowly, continuously, so that even under the noise floor it is possible to retrieve some information. But with digital, under the LSB, there is no more information!</i></b>
This is incorrect. With dither, information FAR BELOW the LSB can be and is encoded. And every properly functioning analog-to-digital conversion system employs dither to do just that.
But even whether or not dither is applied during the analog-to-digital process, no amount of noise applied after the fact will retrieve any additional information.
se
Please Steve,
I sometimes take your side in heated debates, but I think you
are overdoing it in this case. The article is an interview by a
journalist with a representative of a company having a
commercial interest in the topic. Such articles will always have
a flavour of hidden advertisement, and I think everybody who
reads it is aware of that and that one should not take any of
the claims as necessarily true. On the other hand, there is
no reason to assume they are untrue either until reading
them and forming an opinion.
Probably a lot of readers of this forum have read the original
article before, some/many of which do not have the sufficient
knowledge to form their own opinion about the possible truth
of the claims. By posting the article here the claims do end up
under the "microscope" of yourself and other people, who
can point out to the others which of the claims are true,
questionable or simply untrue.
Further, it could be the case that adding a blue LED does in fact
improve the sound, but the companys own explanation for why
it does is seriously flawed. In that case the topic is worth
discussing by those interested in it.
Finally, don't forget that what is true today, may be untrue
tomorrow, and vice versa. Most models we learn at university
are either approximations of the truth or models that do not
take into consideration all the various parameters appearing in
a real-world problem. Many engineers do unfortunately never
realise this. No opinion on your status in this matter indended.
I am a scientist by profession, and I am trained and used to
analyse other peoples claims ruthlessly, but this is not a forum
for scientific articles. There are other fora for such writings. I
also take the liberty of trying to throw off my scientist robe when
writing here, and behave more like a normal human being who
is allowed to, and sometimes do, make errors and unfounded
statements (the latter by mistake or laziness).
****, why did I write this? I will probably end up in a discussion
with you making me a DIYelder faster than I could ever have
imagined.
BTW folks. I saw that I have already been promoted to
"DIYprophet". Please pay no attention to that. Considering
how recently I registered the more correct label would perhaps
be "Plague to the forum" or whatever you would call it in
english.
I sometimes take your side in heated debates, but I think you
are overdoing it in this case. The article is an interview by a
journalist with a representative of a company having a
commercial interest in the topic. Such articles will always have
a flavour of hidden advertisement, and I think everybody who
reads it is aware of that and that one should not take any of
the claims as necessarily true. On the other hand, there is
no reason to assume they are untrue either until reading
them and forming an opinion.
Probably a lot of readers of this forum have read the original
article before, some/many of which do not have the sufficient
knowledge to form their own opinion about the possible truth
of the claims. By posting the article here the claims do end up
under the "microscope" of yourself and other people, who
can point out to the others which of the claims are true,
questionable or simply untrue.
Further, it could be the case that adding a blue LED does in fact
improve the sound, but the companys own explanation for why
it does is seriously flawed. In that case the topic is worth
discussing by those interested in it.
Finally, don't forget that what is true today, may be untrue
tomorrow, and vice versa. Most models we learn at university
are either approximations of the truth or models that do not
take into consideration all the various parameters appearing in
a real-world problem. Many engineers do unfortunately never
realise this. No opinion on your status in this matter indended.
I am a scientist by profession, and I am trained and used to
analyse other peoples claims ruthlessly, but this is not a forum
for scientific articles. There are other fora for such writings. I
also take the liberty of trying to throw off my scientist robe when
writing here, and behave more like a normal human being who
is allowed to, and sometimes do, make errors and unfounded
statements (the latter by mistake or laziness).
****, why did I write this? I will probably end up in a discussion
with you making me a DIYelder faster than I could ever have
imagined.
BTW folks. I saw that I have already been promoted to
"DIYprophet". Please pay no attention to that. Considering
how recently I registered the more correct label would perhaps
be "Plague to the forum" or whatever you would call it in
english.
I don't understand.
If no one wishes to discuss the technical issues of a matter, why allow technical issues to be raised in the first place?
I haven't brought up any technical issues on this matter. I've only addressed technical issues that have already been introduced to this discussion by others.
Can someone help me out here and answer a couple of basic questions?
1. Are technical issues allowed to be introduced into a discussion?
2. If the answer to number 1 is yes, are those technical issues then open to discussion?
se
If no one wishes to discuss the technical issues of a matter, why allow technical issues to be raised in the first place?
I haven't brought up any technical issues on this matter. I've only addressed technical issues that have already been introduced to this discussion by others.
Can someone help me out here and answer a couple of basic questions?
1. Are technical issues allowed to be introduced into a discussion?
2. If the answer to number 1 is yes, are those technical issues then open to discussion?
se
Steve,
I did not complain about you discussing the techincal matters.
Doing that is exactly what I encoureaged and meant by "putting
the claims under the microscope".
What I and many others object to is that you have complained
a lot about the article being posted here in the first place.
Without that article, we would not have had a starting point
for the discussion. Of course, Peter could have made a summary
of the article, or simply said that "I have read that ...".
however in the latter case I think it is preferrable to inlcude or
refer to the source, when possible. He could also have started
the thread by simply asking if or why a blue LED might improve
the sound. However, many would then have asked why he
asked that in the first place, and the article would be bound to
appear in the thread, in one way or another anyway.
I did not complain about you discussing the techincal matters.
Doing that is exactly what I encoureaged and meant by "putting
the claims under the microscope".
What I and many others object to is that you have complained
a lot about the article being posted here in the first place.
Without that article, we would not have had a starting point
for the discussion. Of course, Peter could have made a summary
of the article, or simply said that "I have read that ...".
however in the latter case I think it is preferrable to inlcude or
refer to the source, when possible. He could also have started
the thread by simply asking if or why a blue LED might improve
the sound. However, many would then have asked why he
asked that in the first place, and the article would be bound to
appear in the thread, in one way or another anyway.
Peter Daniel said:
But it's not going to add any noise in the analog domain except by causing random data errors which would have to be indiscriminate and not limited to the LSB which means if it's working as you suggest here, when you play your CD with the blue LED, you should near nothing but "shhhhhhhhhhhhhhhhhhhhhhhhhh" coming out of your speakers and nothing else.
I'm assuming that's not what's happening and you're getting music coming out of your speakers, correct?
If you want to find out if it's having any effect on the data of the CD, put a blue LED inside your CD-ROM drive and try reading a CD-ROM disc. If the blue LED is "working" then your CD-ROM disc should be rendered unreadable.
se
Steve Eddy said:
I agree with you completely on this one, which leaves us
with the case "Perhaps a blue LED may improve the sound,
but it is not for the reason claimed in the article". Then we
have at least two possible ways of looking at the issue:
1) It's probably just imagination
2) Assuming it is not imagination, what could be a reasonable
explanation for the perceived improvement?
"shhhhhhhhhhhhhhhhhhhhhhhhhh"
Hmmmmmmmm....... good advice.
Absolutley nothing has been discussed about the addition of this extra light souce's effect on jitter, Bit Error Rate, or how hard the servo is having to work in focusing the laser. I don't think anyone has scratched the surface of the technical issues involved. I guess denial has always been easier than investigation though.
Is there an optics engineer in the house?
H.H.
Hmmmmmmmm....... good advice.
Absolutley nothing has been discussed about the addition of this extra light souce's effect on jitter, Bit Error Rate, or how hard the servo is having to work in focusing the laser. I don't think anyone has scratched the surface of the technical issues involved. I guess denial has always been easier than investigation though.
Is there an optics engineer in the house?
H.H.
Christer said:
Sorry, my "I don't understand" post wasn't directed at your comments. It was just my puzzlement at why some don't mind technical issues being brought up but get upset if those issues are subsequently discussed.
I really only complained once in my original post. Most all of my posts after that (save for the battery issue) were my responding to those who were upset at my having made the original post.
And in hindsight I should have simply addressed the issues in the sidebar right off the bat as I did a couple of posts above. But the claims made in that sidebar were so obviously laughably incorrect, I didn't think I'd have to point them out.
Next time I'll just stick to addressing the claims.
se
Steve Eddy said:
I assume you didn't understand the article properly. I'm not an authority on the subject, but how I see it is that the LED is creating some sort of noise in digital domain which is then converted into data in analog domain.
The issue here is not that it reads more information that was recorded on CD surface, but it rather helps to generate missing informations and makes the whole presentation more analog like.
It's not about adding error and interference because the amount of daylight that is affecting my playback system for some reason doesn't have anything to do with the sound.
Steve Eddy said:
And in hindsight I should have simply addressed the issues in the sidebar right off the bat as I did a couple of posts above. But the claims made in that sidebar were so obviously laughably incorrect, I didn't think I'd have to point them out.
But then you are making the mistake of assuming that everybody
reading this forum has the same education and knowledge as
yourself. Many do, many others don't, and to this latter group
of people it is not at all obvious. Another day, in another thread
someone might post an article that can only be judged by those
who posses knowledge that you don't happen to have (I am
assuming you are an ordinary non-omniscient human
If you find the topic of the article interesting, would you not
then wish that those who have the appropriate knowledge
discuss it and anlyse it, thus helping you to form your own
opinion about the topic?
As I said above, I entirely agree with your view on this LSB
noise claim. But I must admit I was almost buying it for a while
(hopefully that was just because it is already 3 o'clock in the
morning over here, and I should rather have tucked in long
ago than posting here
Next time I'll just stick to addressing the claims.
se
Not meant as an offense, but a friendly advise, i think you
would find life on this forum running smoother both for yourself
and others if you do so. But please do it, because I do have
the impression that you have a lot of valueable knowledge to
share with us.
Best Regards
Peter Daniel said:
I don't think so (although it is very late, and my brain is tired).
Just as Steve pointed out, you cannot control which bits on
the CD are affected by the noise. It can be any of the 16 data
bits, any of all the error correction bits, even the track index
which might end up as totally screwed up information on the
dispaly of your player. No, if there is anyting at all to this, I think
we have to look for an alternative explanation. There could very
well be one. Many report that straylight degrade the sound
quality considerably. We have this issue with painting the rim
of the CDs, and maybe even the label side. For instance,
Svalander claims that the black Memorex CDRs have superior
sound compared to others. Nothing of this to be taken as
truths, but worth considering in my opinion.
They specifically talk here about the Least Significant Bit and adding noise there. Why, I don't know, I didn't study CD playback system long enough.
For some reason I tend toward Yves Bernard and his theory than Steve's, who doesn't have much to show, except for some doubtful assumptions.
My previous post was directed to him too.
P.S.
What do you really know about controllig the behaviour of the bits on a CD? Like Harry said, the surface has been barely scratched yet.
For some reason I tend toward Yves Bernard and his theory than Steve's, who doesn't have much to show, except for some doubtful assumptions.
My previous post was directed to him too.
P.S.
What do you really know about controllig the behaviour of the bits on a CD? Like Harry said, the surface has been barely scratched yet.
Peter Daniel said:
Yes they do, but as far as I can see there is no way you could
do this by bathing the CD in light. Well, maybe if you synchronise
the blue LED with the data stream and switch it on only when
reading the LSBs. I am not sure if that would be feasible, and
anyway it seems to be adressing the problem in the wrong
way, since you could just as well add the same noise
electronically in a later stage.
But please note Peter, I am not claiming there is no effect to
the sound from using a LED, but once again, I really think
we must look for another explanation.
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