CD stoplight - some analysis

What's this about? I can't be arsed reading 100 posts.

I advocate world peace.

 

It's about 8 pages.

-- Ian

 

Provided it's brought about by the equitable distribution of green pens and the liberal application of polarised creams, you'll be fine.

 

I see nobody has answer the why green question.... Well nature has this solved in that most all plants are green and why I hear you ask, so as to absorb the near infra red light they us to fix carbon dioxide to starch. Just look up any treatise on photosynthesis. The way you can cheque this is to look at green object using a red light and see what colour the reflected light is....the object will look black as there is no reflected light. The green pigment will absorb the red light. In white light a leaf looks green because the red light is removed from the reflected white spectrum. Black will do a similar job but black absorbs all the spectrum.

 

Oh now come on Tones. People using simple science in evaluating soundquality (or PUSSIES for short) really need to get out there and use their ears.

Although I accept, given your inabilitiy to tell your LP12 and CD player apart, you may be somewhat disadvantaged in this area.

 

That's something that Stebbo keeps pointing out whenever we have this discussion. However, I was using the green pen tweak (and hearing it work) in the late 80s, some time before any of the audio newsgroups existed. And I'm not the only one so that little story can be well and truly kicked into touch.

Michael.

 

Michael.

The groups you talk about existed well before the late 80's just in a difference format. They tended to be based on University servers on the NSFNET.
I am sure you are aware that the NSFNET was an original part of what has turned out to be the 'net.

 

Zanash
I was under the impression that Photosynthesis use UV light not IR light.
I am more than willing for the biologists amongst us to correct e here.

 

But the alternative group - People Applying The Human Ear To Imagine Codswallop - are?????

 

Oh come on Robbo! That has to be one of the most naive statements I've ever read on my time on forums. Have you ever heard of the term "commercialism"? There are other products or transports out there that don't have green or even purple paint anywhere and they play superbly so what exactly are you saying? That just because Wadia/Teac have used the colour green on their transport mechanism therefore there must be some validity to the theory of the green pen/ink? You boys are just too trusting or let me guess, you've studied the lab test results. Dear, dear!

You know, at this rate, I am now seriously contemplating entering the audio field with some snake-oil product or even my own brand of cables as there is so much money to be made from the suckers out there masquerading as audiophiles.



Enjoy the music,

Lawrie.

 

I'm well aware the usenet groups have existed in some form or other since the early days of the net allthough I'm not quite sure when they started. However, they were almost exclusively limited to science, education and computer topics. I don't know for a fact but I'd be amazed if any of the rec.audio tree existed then.

Anyhow, the whole "it started as a joke" line is totally irrelevant as to whether it works or not. Much greater scientific discoveries than the green pen have been made as a result of a joke suggestion.

Michael.

 

rec.audio.high-end started Jan 24 1990. I don't know when rec.audio.ludicrous-green-pen started.

Obviously there was an earlier mailing list.

Paul

 

OK so, as he can't/won't back up his assertions, Merlin is just rabble-rousing.

If stray light is such a problem, how then does the most expensive transport owned by anyone here (more expensive than most peoples entire systems - with the possible exceptions of Mr Parry's Salisbury pile and Bub's stacks of angle iron ), the £15350 Metronome Kalista

stand any chance of working, since the CD is completely in the open? (BTW: It does have a nice blue LED light shining around the CD while in operation.)

 

Oh but I can tell the difference - the LP makes crackles and pops and the CD doesn't - dead giveaway...

And you gotta admit that I'm no ***** - even though I don't believe in them, I have actually got out there and tried all these things, and I have found every one tried so far wanting.

The hearing? Excellent, although at 56 I'll clearly have lost the ability to hear some high frequencies (we all do). Perception? Perhaps faulty. But, as Clark said to Viviene in the last reel of "Gone with the wind"...

The point is that one cannot say that these things "work", when they fail to work for a substantial slice of the population - I haven't totted up the precise numbers, but I have the impression that the pen "works" in about 50% of cases. Now, were it only a few percent, one could say that this small group is lacking something that the rest of the human race has. However, the fact that a lot of folk don't hear a difference indicates that the people who hear a difference hear one because consciously or subconsciously they want to hear one.

Now there's no harm in that - if their ear/brain system says there's something there, then there's something there, in their version of reality. Have a look at the "New Scientist" article I mentioned over in the "Chat" section. It makes the point very strongly that we all live in our own realities, each of which is subtly or not so subtly different from everyone else's. My red is not the same as your red, and my idea of a bitter taste is not the same as yours. Ditto my idea of what something sounds like. The idea that vinyl sounds different from CD is not universal, but then perhaps some of us just listen to the music and don't pay much attention to what is doing the playing.

It follows that it is simply not possible to say "the green pen works - period". I have no problem with "the green pen works for me - period".

 

Do me a favour Lawrie, you dont think I would go out and buy something just because I read some fancy marketing speak do you? I use my ears remember (something that I have been roundly attacked for saying on this very thread). FYI, there is plenty of expensive of kit/accesories that I have heard and neglected to buy because they do not make the grade sonically. I am actually quite a canny buyer and rarely lose much money, unlike those who buy new (such as yourself?) who buy kit new and therefore will lose it by the bucketload.

 

To be fair Neil, I think Lawrie does at least perform some kind of listening test, although these are compromised at best.

If he really wanted to do the "blind thing", he would allow changes to the sytem without any idea of the products being tested. Then he might get more of an idea once his internal predjustices had been bypassed.

Graham, I accept it, the Pussies win! I will delete my posts, I really don't want to waste anymore of my precious time on this earth conversing with pussies. I'll stick to personal insults in future, that seems to be far more satisfying

 

Yes, Lawrie has made me well aware of his listening tests. He was accusing me of buying decisions based on measurements and marketing which is nonsense and so I was just trying to rebut his accusations.

He'll still lose money by the bucketload if he buys new though. But I suppose if you have money to burn........

 

Much snipping to keep it short.


That Michael is the nub of the whole question and the reason for Issac starting this thread.


I have posted this before but will again as it is how it works. That is beyond doubt. Just look up the design data, it is in the public domain these days
...
somebody was thumbing through an old laser physics book and happened upon something called a "Brewster window", where the glass seal at the end of a helium-neon laser tube was sealed with glass set at 37 degrees. This was before the days when the mirrors where an integral part of the tube itself.

ALL of these scams totally ignore the fact that the entire pickup system is immune to alledged problems these toys are supposed to correct. The laser reading is done by coherent interference and DOES NOT depend upon reflection, as the people who make these things claim.
In order for edge reflections to have ANY effect, the total round-trip distance traveled between the current pit being read and the edge MUST be an exact integral multiple of the wavelength, AND the returning spurious reflection MUST be significantly brighter than the direct beam illumination AND has to have been created in the first place. That means that the angle of incidence has to have been sufficiently shallow (not 90 degrees, like the entire system is configured, but more like 20 degrees!) to begin with to cause enough energy to find its way to the edge.



Let us also not forget this key design point!

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!

and of course this little ditty

Still to date, not a single person has advanced ANY actual impartial or objective data to support the assertion that it makes any difference.



So apart from all that I am still interested why you have to use the £20 version rather than the £0.99 version of the pen.

 

I'm not saying I know how it works and I believe the manufacturers don't know either. Putting the pseudo science about reflections in the literature is something I think they feel they have to do because the alternative would be "we don't know how it works, but it does".

The reasons I get the £20 version and not just any old green marker pen are:
a) it has a convenient notch in the felt tip which makes application a great deal easier.
b) the ink in it dries to become an opaque matt green whereas ink from marker pens I've tried remain translucent.
c) the ink from the £20 version has presumably been tested to ensure that it doesn't have any solvents that might damage the CD coating.
d) the difference in price really isn't that important to me. I have about 600 CDs and a single pen will probably do about 100. I don't religiously do all my CDs (so far maybe 50 or 60 have been done) and I'm still on my first pen. I'd be happy to pay the extra £19 just to have the notch in the felt tip

Incidentally, when I was a poor student in the late 80s I did use an ordinary green marker pen.

Michael.

 

Michael
Your honesty is refreshing. Thanks