Todd R
Headphoneus Supremus
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- Sep 27, 2001
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Which side is the bevel cut on? Lable side or data side?
Originally Posted by Brandon_Ottawa Does green or black work? A hot tip in audio expert circles is the colouring of the CD's edge with a felt pen, to absorb the light scatter. The effect unfortunately doesn't deliver on its promise. Green as a complimentary colour to the red laser should bring better results, this is however often not the case as many lasers work with the infra-red spectrum. Simple and effective: the 36° bevel Turning round and absorption In exhaustive tests biochemist Dr. Erich Schrott and engineer Wolfgang Schneider have looked for ways to eliminate the disruptive reflections. They found an amazingly simple, yet highly effective, tuning method. The CD's outer edge is bevelled and works as a trap for the light scatter. Black colouring absorbs additional misrouted laser light. An edge angle of 36° brings audibly the best results." |
Originally Posted by BradJudy Just a couple of science notes here. ALL CD player lasers are infra-red, not red, so I'm not sure why they reference red lasers. Since the lasers are infra-red (non-visible), the visible color of a marker doesn't directly relate to whether or not it absorbs infra-red light. There are substances that absorb all visible light, but allow infra-red light to pass unabsorbed. Cutting an angle on the side of a CD could keep laser light from passing out the edge because of total internal reflection, but I don't know how this would improve playback. Since the angle would be dependant on the index of refraction of substance (generally ~1.55-1.6 for polycarbonate for CDs), it would vary if the index of refraction of the substance varied. Since the index of refraction plays into reading CDs properly, it shouldn't vary much. For polycarbonate, the critical angle for total internal reflection is ~38-40 degrees. Anything at that angle or greater would internally reflect and not go past the edge of the disc. I can draw a diagram later, but because of the way the angles work, the 36 degree cut is actually a 54 degree angle for the purposes of this discussion, well into the range for total internal reflection. In fact, there is a wide range of angles at which this should work. This is a neat webpage on total internal reflection: http://hyperphysics.phy-astr.gsu.edu...pt/totint.html Again, I don't know how this would improve playback, but the science is much more sound than markers for blocking stray light. |
Originally Posted by Asmo Would this improve the quality of the audio that is ripped from the CD via a computer? |
Originally Posted by mikeliao No seriously, I'd like to give it a try. Who do we PM for the current package holder and how does the package holder decide which person to send it onto? |
Originally Posted by BradJudy Just a couple of science notes here. ALL CD player lasers are infra-red, not red, so I'm not sure why they reference red lasers. Since the lasers are infra-red (non-visible), the visible color of a marker doesn't directly relate to whether or not it absorbs infra-red light. There are substances that absorb all visible light, but allow infra-red light to pass unabsorbed. Cutting an angle on the side of a CD could keep laser light from passing out the edge because of total internal reflection, but I don't know how this would improve playback. Since the angle would be dependant on the index of refraction of substance (generally ~1.55-1.6 for polycarbonate for CDs), it would vary if the index of refraction of the substance varied. Since the index of refraction plays into reading CDs properly, it shouldn't vary much. For polycarbonate, the critical angle for total internal reflection is ~38-40 degrees. Anything at that angle or greater would internally reflect and not go past the edge of the disc. I can draw a diagram later, but because of the way the angles work, the 36 degree cut is actually a 54 degree angle for the purposes of this discussion, well into the range for total internal reflection. In fact, there is a wide range of angles at which this should work. This is a neat webpage on total internal reflection: http://hyperphysics.phy-astr.gsu.edu...pt/totint.html Again, I don't know how this would improve playback, but the science is much more sound than markers for blocking stray light. |
Originally Posted by lan Computers don't count since it's reading the audio not as audio but data so transport based jitter is out of the equation. |
Originally Posted by Skarecrow Now correct me if I'm wrong now, but there is zero "audio" on a CD. Since all CD-based audio starts off digital, if this tweak does somehow work (call me skeptical), it should apply to all CDs. Whether the information is passed directly from the laser mechanism to the DAC or whether it is intermediatly stored on disc shouldn't matter, so long as the transfer is bit perfect. And that all being said, you can't read binary ones and zeros as anything but ones and zeros. there is no "strong ones" or "weak zeros" or whatever |
Originally Posted by Todd R Which side is the bevel cut on? Lable side or data side? |
Originally Posted by ampgalore This looks mighty dangerous. I think I'll pass. |