[Todd R]

Which side is the bevel cut on? Lable side or data side?

 

[mikeliao]

Finally. We've got the uniforms. We've got the motto (I think). Now we have the weapon.

Head-Fi Special Attack Force (or somthing like it, I forget) equipment list is now complete. Training to commence shortly, beginning with throwing fresbees and eventually working up to our secret edged CD weapon.


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?

 

[BradJudy]

Quote:

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."

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.

 

[Welly Wu]

Quote:

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.

Like Radrd said before, audiophiles fall into the "sometimes some of the time" category. I should know. I did. However, this is really cutting it too close for me (pun intended).

 

[Asmo]

Would this improve the quality of the audio that is ripped from the CD via a computer? Perhaps rip a cut CD and regular CD, make a small 1-2 minute long flac or ape of this, and pass it around (if there is a difference, wouldn't it apply to this as well?)

 

[lan]

Quote:

Originally Posted by Asmo Would this improve the quality of the audio that is ripped from the CD via a computer?

Computers don't count since it's reading the audio not as audio but data so transport based jitter is out of the equation.

 

[Wmcmanus]

Quote:

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?

Good question! Send your PM to me, and I will coordinate the list. Be sure to include your name, address, and phone number. I'll then compile the list so that folks will know who they will be receiving the package from and who to send it to next.

In general, it will be first come, first serve, but subject to a little common sense (i.e., if two people live within a few miles of each other in California, there is no sense in sending the packege to New York and then right back).

As this thread develops, it will be interesting to see how the proportion of respones changes (i.e., those who would prefer to poke fun while remaining ignorant on the subject relative to those willing to try it and then report back based on experience rather than assumptions).

 

[Wmcmanus]

Quote:

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.

I don't use the markers myself very often and have never done any testing to see if a disc that has the black marker treatment sounds any better than one that does not. I'm skeptical about this as well, and perhaps this is why I don't normally bother with the black marker treatment (or green, or whatever). In fact, my Audio Desk was a demo unit so there was no black marker included, and I was not even aware that they recommmneded this.

My experience is based on the CD cutting alone, and/or in combination with Walker's Audio Vivid, so I make no claims whatsoever about the effects (if any) of black markers. What I have observed is that discs spin much more naturally when they have been trimmed. The edges of manufactured discs are not perfectly smooth (run your finger around the outer edge of one if you don't believe me), so all the Audio Desk does is to remove little bits of the outer edge. On my Shanling T200, I can stand above the player and watch the discs spinning, and there in no wabble at all with a trimmed disc. For some reason (and trust me, the science is beyond me) the trimmed discs sound better. The difference is not overly dramatic, but it is quite easy to detect on most trimmed discs. At least I can pick out which one has been trimmed and which has not been trimmed 9 times out of 10.

 

[Skarecrow]

Quote:

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.

Now correct me if I'm wrong now, but there is zero "audio" on a CD. It's a polycarbonate covered metal disc with pits/valleys that are read by a laser as 1s and 0s that digitally represent audio. All CD-based "audio" starts off digital and then is fed to a DAC (whether internal to the CDP or external via spdif coax/optical ports) to be changed into analog electrical representiations of audio, which are then fed to a speaker of some variety... changing it to something we can finally hear.

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, it's either true or false. 1 or 0. what that means is that if this cutting tool IS making a difference, then it is changing the way the laser would normally read the pits and valleys on a disc. Whether it's changing them for better or for worse is up to you. Is it reading them more accurately than normal? That question is beyond my knowledge.

 

[lan]

Quote:

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

Well the disc format/structure and playback for audio CDs is different than a data CD. Audio CDs have less error correction, are read at 1X, and are affected by jitter which make them more suseptable to quality loss during playback.

If this tweak does make reading discs better then yes it would affect all CDs including data ones. Data CDs wouldn't benefit in the same way though.

 

[Brandon_Ottawa]

Quote:

Originally Posted by Todd R Which side is the bevel cut on? Lable side or data side?

The bevel is cut on the data side.

 

[Edwood]

Uh, the label side IS the data side technically, BTW.

But you're talking about that it cuts into the reflective side opposite of the label side, right?

That would be the safest area to cut.

I use a computer as a source too, so I don't think I'd be able to hear the difference after ripping the tracks either.

Brandon: Can you show a close up pic of the beveled cut, along with the shavings, to give us an idea of how much/little it actually shaves off?

-Ed

 

[Brandon_Ottawa]

Edwood...here are some quick pics that I took of the shavings and the disc's bevel after cutting and marking. The shavings look like dental floss.

My best results are obtained by cutting at about 7500-8000 rpm on the audio desk. I like to make a final "clean-up" cut at the machine's max speed (9000 rpm). Marking the beveled edge is a piece of cake...you just hold the marker in a stationary position against the beveled edge while the disc spins at 50 or so RPM. The end result is very clean.

A word of caution: The Audio Desk improves the sound of SACD's, BUT...I wouldn't recommend using the lathe on these discs. SACD's seem to have a very thin laminate that tends to develop stress cracks from the cutting process/handling during application of optical enhancers and cleaners. Some of my cut SACD's have stress cracks around the outer edge (approx 0.1 - 0.5 mm in length). I haven't had any problems playing any of these discs. I still continue to bevel my SACD's. The sonic improvement that I hear is more important than a cosmetically perfect disc.

I have never had any problem with any CD's that I have cut. They are 100% problem free.

The CD is a little dusty and statically charged after throwing the shaving on it. The marking was done while the disc was clean. A good reason to have a Bedini!

 

[ampgalore]

This looks mighty dangerous. I think I'll pass.

 

[Todd R]

Quote:

Originally Posted by ampgalore This looks mighty dangerous. I think I'll pass.

Aww ya big chicken

Brandon,
How much you want to circumcise some of my disks? I'd like to hear for my self what this does.
TR