[Review] Densen DeMagic demagnetising CD

Let me say this to start.

I work for a LARGE IT company and as a Graduate many years ago and 20 year plus in the job technician have worked with a lot of technology
I have been to some of our companies developments labs and worked on the development of new products. The details of which arent important to this thread.
What is important in that whilst in America I sat in the same office a gentleman who used to work for Phillips. So what you may ask?

Well his was one of 6 names on the original patent for the CD technology. So I think it is fair to say he knew a thing or two.
I still have some text books here that cover the design issues as the are still relevant to DVD which is one of the technologies I have worked on

Now in my post timed at 10:01 today I set out briefly how a CD player works. I fully accept that it was a brief outline but it summarised the relevant bits.
If you wish to argue the point, then go and get the patent documents and quote where I am wrong.

Here is a link you might find interesting
http://web.archive.org/web/20011224210544/http://emedialive.com/news/2000/07/news0700-02.html
All it takes is a little bit of research to find out a lot of the stuff I mention. What I find so incredulous is that no one on forums like this wants to go and do it.

I have met Dana J Parker. His credentials are beyond reproach.


Now bearing in mind that the green pen scam says that it stops the scattering of stray light and the design spec of the Cd player does not back this up, to me the pseudo science is just plain WRONG.

I have at my fingertips at work a way of measuring errors on both magentic devices HARD DISKS and Optical Devices CD/DVD.

Have done this on the two CD's I mentioned and found nothing. In fact the none green striped one had less errors. both were tiny.

I cant comment on the tests other people have done, but are they truely blind? or have people been told that you have a great method of improving sound...
I dont know the situations so wont go any further.

Michaelab
I accept your point about the analogy but what I was trying to show is that if you have a decent grasp of the facts of the internal combustion engine, you wouldnt even try it.
I have a more than decent grasp of the electronic facts as my degree and work expereince testifies.


I have no agenda. Dont take it so personally. I have already said if you want to spend you own money please be my guest.

I was only offering some facts and some opinions on the subject that was put up on this forum for discussion.
 
Originally posted by penance
and i work for one of the worlds largest IT companies, WTF has that to do with anything:rolleyes:
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Firstly, I thought you werent listening to me anymore!

Secondly dont selectively quote. If that is all you can offer then dont bother.
You can see the whole paragraph. Just like everyone else
 
Originally posted by Robbo
Tones,

Sorry for hijacking your thread:o
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No problems, ol' bean, I find the whole business of perception fascinating, the way that some of us hear things that others can't. I really think that our individual heads are responsible. Sound only exists in our heads, the intervening space being only compressions and rarefactions in the air.

So far, I have proved myself totally unworthy as a hi-fi enthusiast and should stick to making comments on music. I tried Mana, and it failed to do a thing, ditto exotic power cables and now this allegedly demagnetising disc. I'm sure that, if I were prepared to buy one of these green pens, I would hear no improvement. I accept that TonyL, Michael et all really did hear what they said they did. But why did they? And why did I not? Are some people psychologically disposed to hear a difference? For example, take the sceptics who heard something. They were told what was going to happen. "Ha, ha," they said, "pull the other one." But, having been introduced to the concept that a change could be possible in such circumstances, were they subconsciously ready for one, or to interpret what they heard as one?

On the other hand, are the sceptics such as myself, convinced by education that no such change is possible, rejecting any audible change as impossible and therefore non-existent?

As I've often said before, I am no good at hearing subtle differences - in interconnect tests, I have caught myself wanting to hear a difference ("I've spent £XXX, so I should hear a difference"). So now I employ a very hard test. I remember how my LP12 buried my old turntable - it was startlingly better. So, I look for that standard. This is only possible with new boxes, I suspect. Fine by me, I won't waste any more money on gizmos.

Anyway, just some thoughts, and I'd be interested in hearing what folk think.
 
Well Tones

My wife is an ENT consultant. Whilst not an expert in Psycho acoustic research she ha mentioned a trial they did at Med school.
they played two identical sounds to 30 subjects (all med students). 29 of them reported differences in the sound.

But they were exactly the same. they were some form of machine generated stuff.

One of her collegues has had a few papers published on similar subjects, so I will get her to find out some info.
The stuff I have read on the Audio Engineering website has shown that once a person is told that something has been changed they will report a difference 99.99% of the time, even though nothing in fact may have changed at all.

In terms of raw ability, the human ear is provably
(and has been proved, for nigh on a century in terms of actual
objective verification) quite poor. It is an extraordinarily
band-width limited device, especially considering the data rate
of the auditory nerve. Instruments can be had, easily at that
that are faster, have more bandwidth (by a huge margin) wider
dynamic range (they don't suffer from the gross masking problems
of the ear), and so on and so forth.

The secret is the processing behind the VERY limited
psychophysical capabilities of the ear, i.e., interpretation in
the brain, which is able to to some pretty serious pattern
matching on its severely limited input. And, it should be noted,
it is VERY easy for those interpretations and their conclusive
outcomes to be influenced by NUMEROUS inputs, beyond those
traveling along the auditory nerve. And that's the problem

Anyway, if you are interested I will get the data and post it or at least a link, If I can of course.
It might be on a subscription website
 
Originally posted by TonyL
I find it has the most effect the older the gear is that it is played through
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Tried it on my Mimik, Tony, using my standard test CD (Pinnock's version of Handel's "Water Music", because I know every nuance of it). And the difference? None that I could hear. Sure you wouldn't like a matched pair of DeMagic discs?
 
Originally posted by stebbo


I have at my fingertips at work a way of measuring errors on both magentic devices HARD DISKS and Optical Devices CD/DVD.

Have done this on the two CD's I mentioned and found nothing. In fact the none green striped one had less errors. both were tiny.
I was only offering some facts and some opinions on the subject that was put up on this forum for discussion.
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Stuart, you may find on this forum more that one or 2 people have equipment like this as well, and maybe a full spectrum analyiser too, I would go as far as to agree agree with on the measurements front, I have GB's of data to surport how/what your discribing, however as I said before something shouldn't make any difference, and there is no Physical or sicentific reason either, but yet they do
Lets take the pen, now you state you tried 2 discs and it made no difference, I would also agree :eek: However I have plenty of discs which do benefit.
A lot of cd manufacturers do treat the inside of their players lids, draw and transport compartments with green paint, even the wadias (later ones) uses green platter and spinners.
Now, just surposing we bias up the photodiode emitter, with say a outside source, emitting into the laser head area, that is configurable & switchable, carrying it's own indepent powered source, and then hook up a scope & full analyiser, select a suitable constant test tone, measure the effect first on the scope, the a FS run, then place a indentical treated disc and preform the same preocedure, I will place a small wager that you'll see no measureable difference, on the S/A, or any thats visiable on the scope trace, however I/can and others in lab (who are bigger sceptics then either Tones or Ranson), not all the time for sure.
Now change the bias of the light wave length of the laser, then see what happens, then preform the pen test again :D most interesting.
At the end of the day, they'll will be strong pro's + Negitives for both sides, with various evidence brought forth from either camps, you have your own ears Flawed or not, it's your reference, I' haven't got golden ears or particularly special hearing, however I can tell a difference from sound that is different from a know reference, which is used for an origin.
Still as Merlin would some thing to get your teeth into :) Wm
BTW we don't sell the pen :eek:
 
The reasons the manufacturers claim for why the green pen works may be complete BS and make no sceintific sense but it does work so, as I said before, I don't really care how it works.

Michael.
 
Originally posted by michaelab
The reasons the manufacturers claim for why the green pen works may be complete BS and make no sceintific sense but it does work so, as I said before, I don't really care how it works.

Michael.
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If you dont care that is fine.
To me, when I find that a manufacturer is quoting nonesense and that is not just in the audio world I may add here, that puts a large amount of doubt in my mind. If it doesnt for you then that is fine.

Wadia-Meister
If you want to "bias up the photodiode" please do
But! that doesnt happen in a CD player. I have no doubt we can construct an experiment to force something to happen, but that is why players are design as they are.

Please re-read my original post of 10:01 yesterday on the way that the pickup system works. That is beyond doubt

Now if the scientific explaination has been shown to be nonesense on the green pan issue and you say it works.
What is happening?. Why hasnt anyone patented this and made a lot of money out of it.
From my research there is no patent for this "technology"

Also bearing in mind that not one Disc manufacturer puts green stripes on there discs from new when the cost would be as close to zero as makes no difference, as something too.

From what I can see here we are moving into the area of psycho acoustics.
I dont really wish to go there as this tread will last about 20 years if we did.

As you said eariler on if you are happy to spend £20 on a green pen...Why you dont go to WH Smiths and get one for 99p I dont know, but is you want to spend £20 on a green pen then That is your right.

Actually why dont you to WH Smiths and get on for 99p?
 
The link doesn't seem to work allthough by looking at the link it would seem you searched on "green pen" in the Usenet group rec.audio.tech.

I added the term "joke" to the search and only got a few hits, mostly by some guy called Dick Pierce claiming it got started as a joke in the rec.audio.tech newsgroup. Unfortunately for him I had read about (and was using) the green pen tweak in around 1987 which I'm pretty sure is long before rec.audio.tech existed (In those days Usenet groups existed but were largely computer related discussions). So, at least his account of how it started is BS.

Michael.
 
OK, I think I found the post you were looking for (from rec.audio.tech):

Here's the link:

http://groups.google.com/groups?q=g...=off&[email protected]&rnum=13

I think it's time we all recall how "green pen" stuff got started.

It started, with me (among others) watching, when a techie type
net.audio reader said "well, if you're so worried about the
laser light leakage, why don't you paint the outsides of your
CD black to catch it", in a discussion where somebody was offering
up an observation that "CD players are dangerous because they
have a laser inside them".

A few weeks later, somebody took this sarcastic quote
seriously, and announced that indeed green permanant markers
improved the sound of the audio out of a CD player.

Nobody has once shown a verifiable mechanism, and
nobody ONCE has shown the ability to discriminate between
a green-inked CD and a non-inked CD in a double-blind test
either, to the best of my knowledge. Certainly, nobody has reported
a verifiable and properly controlled test (or anything close)
here, by reference or article.
--
Copyright alice!jj 1995, all rights reserved, except transmission by USENET and like facilities granted. Said permission is granted only for complete copies that include this notice. Use on pay-for-read services or non-electronic media specifically disallowed.
[email protected] Member HASA - Atheist Scum Division, curmudgeon caucus - Numquam Nihil Preparandum
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That's no more evidence than anything else. It's invalidated for the reasons I mentioned in my previous post.

Michael.
 
Originally posted by michaelab
The link doesn't seem to work allthough by looking at the link it would seem you searched on "green pen" in the Usenet group rec.audio.tech.

I added the term "joke" to the search and only got a few hits, mostly by some guy called Dick Pierce claiming it got started as a joke in the rec.audio.tech newsgroup. Unfortunately for him I had read about (and was using) the green pen tweak in around 1987 which I'm pretty sure is long before rec.audio.tech existed (In those days Usenet groups existed but were largely computer related discussions). So, at least his account of how it started is BS.

Michael.
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Some of the stuff has been missed off sorry.

No it wasnt Dick Pierce,
Go to Google and find rec.audio.tech
Search on Green pen in that group only
Page to the second page and the third item down which has a thread 12 posts long In there dataed 18 sept 1995


It refers to anonther group.



I dont see how your previous post invalidates it as he doesnt refer to dates

But anyway see me last post.
 
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See above, I got the post you are referring to.

Even if it did start as a joke (which is possible) that doesn't mean it doesn't work. If you don't believe the many people here who know it works how about the following quote from John Atkinson of Stereophile:

"The cost per disc of this tweak is almost zero, meaning that it offers a big bang for the buck and can be confidently recommended. But as to why CD Stoplight has any effect, don't ask!"

It was also on the Stereophile Recommended Component list from 1990 to 2001.

(by "It" I'm referrering to the Audioprism Stoplight commercial version of the greeen pen).

Michael.
 
I know we will not agree on this but let me lay out a few more design issues before I sign off this thread, This is mainly for people who are thinking about why does it work...

The question is that IF such an audible effect exists (you know my views, but that isn't important to this post) IT CANNOT be due to the explanation proffered, because such an explanation is contrary to known physical behaviour. Behaviour which has been shown to exists unequivocally in millions of experiments and, which if wrong, would mean that vast arrays of devices that work now could not have ever worked.

The green-pen advocates wrongly connect cause and effect together, trying to support their assertion that the green pen works. Instead of concentrating on whether it DOES work, they try to legitimize the claim by attempting to proffer and explanation for HOW it works. And the explanation, based on notions such as complementarity of color and changing wavelengths and such, are simply wrong, and do little to enhance
the credibility of the claim.

As it is, however, bogus theories of scattering and reflection and
absorbtion and coplimentary colours and all sorts of hocus pocus have been advanced to legitimize claims of an audible phenomenon that themselves have not been conclusively demonstrated.

First, the laser diode in the CD player is NOT red, it's infrared, with a wavelength of about 790 nm. Not a single person using the "complimentary colour" argument has dealt with this issue.

Second, "complimentary" is a purely visual concept. It is how the eye and brain respond to colour. It's not related to how interference, scattering, absorbtion and other such physical phenomenon work at infrared wavelengths.

Third, the absorbtion in the red wavelengths anyway of most green dyes is not very low. Thus, if the drawer in your CD player was black to begin with, you may have made the situation worse by painting it green.

Fourth, much of the reflection of a painted surface may be specular, and thus not affected by the actual color. This is true if the painted surface is glossy. Specular reflection can be broadband, while the diffuse reflection from the dye or pigment can be narrowband. Look, for example, at the reflection of the sun on the paint of a red car. The specular reflection is about the same color of the sun: it's not red. So painting
your drawer may have made the situation worse from THIS aspect as well.

Fifth If you've ever seen a diagram of how the optical readout scheme is implemented in cd players you would realize how silly the stray light argument is. The optics (lenses and beamsplitters) in the path between laser diode-cd surface and detector are coated with a multilayer dielectric V-coating whose sole purpose is to allow light around 790 nm to pass and BLOCK LIGHT OF ALL OTHER WAVELENGTHS! The stray light theory is therefore, BOGUS!

Sixth,Green light has a wavelength of 514 nm and the laser diodes used in cd players emit at 790 nm. I would be very interested to hear your theory on how exactly a layer of green ink which is definitely NOT optically flat can reflect anything. It may possibly absorb some light, but it would be a clever trick if it could reflect exactly back to the detector!
In fact if it really works as you say, then all the scattered light that is sent back to the detector would actually make things worse (much worse)!

Seventh, still to date, not a single person has advanced ANY actual impartial or objective data to support the assertion that it makes any difference.
 
Seventh, still to date, not a single person has advanced ANY actual impartial or objective data to support the assertion that it makes any difference.
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As ever it all comes down to which you trust; 'science' or your own ears. Science once thought that the sun went round the earth, that people would die if they travelled at over 30 miles per hour etc. Science is still very much an evolving concept. The most stupid thing in the whole world is a stubborn or arrogant scientist; the kind of person who is convinced that just because he does not know how to measure a phenomenon it can not exist. A stubborn or arrogant scientist is not a scientist!

The whole pointy of science is to find new ways of measuring and understanding. If many people hear a difference with the use of apparently absurd items such as green pens, cables, stands, weird CDs from Denmark etc then it is simply time to find a new way to measure what is being heard, the existing methods are obviously not sufficient. The ears are usually right, the science always needs improving.

Tony.
 
Originally posted by TonyL
As ever it all comes down to which you trust; 'science' or your own ears. Science once thought that the sun went round the earth, that people would die if they travelled at over 30 miles per hour etc. Science is still very much an evolving concept. The most stupid thing in the whole world is a stubborn or arrogant scientist; the kind of person who is convinced that just because he does not know how to measure a phenomenon it can not exist. A stubborn or arrogant scientist is not a scientist!

The whole pointy of science is to find new ways of measuring and understanding. If many people hear a difference with the use of apparently absurd items such as green pens, cables, stands, weird CDs from Denmark etc then it is simply time to find a new way to measure what is being heard, the existing methods are obviously not sufficient. The ears are usually right, the science always needs improving.

Tony.
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I agree with you on some points here, but you only quote my seventh point ignoring all of the facts of CD design and manufacture.

The ears are usually wrong I am afraid. The brain gets in the way.

Think of this.

We as humans have the ability to tune in or out sounds

The Ear is a fine device, but unfortunately it is connected to the brain, which is both a fantastic example of evolution but is rather easily fooled.
It is a known fact that the human mind will work like an equalizer on sound input and listen a bit harder for certain areas and detune for others once we get enough exposure to the sound.

Case in point - people who have a grandfather clock. I had one growing up and to this day still walk all around my parents house and cannot hear the thing chiming - I have permanently tuned it out. People also tune out aeroplanes and motorway noise. They also tune in specifics like their kids crying and TV programs in a noisy environment.

There are have been many experiments by hundreds of scientists with thousands of subjects that show the the brain ear connection is very easily fooled. Just look it up. It isnt difficult to find.


But The last post of mine was to focus on the technical aspects of the claims made. They are false. That makes me very very wary.

As I have also said it is only £20, so what is the problem??

Well certainly for me I dont want to be ripped off. £20 for a green pen that started as a joke and goes against how a CD works is ripping off to me

Just like a power cable I read about for £1700+. Even if it works, which isnt the point. That price is bordering on the criminal.

It wont be long before Colombian drug dealers are getting into audio with that sort of profit margin!!!:MILD:
 

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