Green LED in CDP


My '86 Philips CD650 has one above the CD. Part of the front is transparant, so you can see the CD spinning. Well it does work, you can see the CD... :)

Guess that is not what you want to hear, but since it still works, it don't know if it makes a difference if it is off. Since the machine is not tweaked or so (first 16 bit chipset/5532 opamps), i guess
other tweaks would make a bigger difference. Personally i don't believe so much in this.

In those days the LED was installed to make the machine look interesting.


The green LED is suppose to be the active version of the green marker tweak. Some people said that they heard an improvement when they paint the edge of their CDs with green marker. One of the Krell CD player also has green LEDs in the transport. I wonder what's the scientific explaination behind this.


2002-05-17 8:48 pm
The "scientific" explanation is that lighting up the disc area with a colored lamp makes people think there must be a scientific reason for it so they will pay more or they will decide to buy this one instead of the one that doesn't have the LEDs lighting up the disc area.

"Gee, if they go to that sort of trouble, there must be a good reason, and if they pay attention to that much detail, the rest of the circuits MUST be the best there is..."

The marketing department was working overtime again.

I have done the LED mod to my CDP and I couldn't hear any improvements. But the green light sure looks cool. :D





With CD

With CD
The green paint trick was supposed to work based on the light <i>absorption</i> properties of the green paint. I guess the idea was that some of the laser light might be reflected / refracted around inside the disc by the angled sides of the pits, and some light would find it's way back to the pickup after bouncing off the edge of the disc from inside. Since green paint absorbs red wavelengths, the thought was that this would stop these reflections from wandering back to the pit, thereby improving the effectiveness of the pickup in some way. I suppose I can concede that this might, just might, have some tiny measurable impact on the bit error rate and/or jitter of data coming off the disc, but boy, it's a stretch.

Now, as for green <i>lights</i>... this has got to be a gimmick. I can't imagine a valid reason why this might work.