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In Reply to: RE: A valid test for a CD player posted by KT88 on October 14, 2009 at 06:19:04
I would summarize the situation as follows. If you want to understand the QC issues related to disks and disk drives, then specialized knowledge and specialized tools are required. If you have audio on CDs that you don't want to lose then you must treat the disks with the greatest care. In addition, without backup copies you are still at risk.
There is no way to intuitively understand issues related to the quality of data recorded on a disk or the performance of a disk drive in dealing with data errors. In particular, that fact that a disk plays well on a variety of players today does not mean that it won't suddenly deteriorate overnight. Similarly, the fact that a drive can play a bunch of damaged disks well does not mean that it will continue to do so, nor that it will play other damaged disks. This area is best treated as a "logic free zone".
When I get a CD I rip it to my computer system using software that takes special care to get it right. It turns out that there are no problems with perhaps 95% of disks, but lately I've come across some old CDs that can't be read even though they have no scratches. This is the case on three separate computers, each with its own drive. Unfortunately, this music is lost for me, because I never made a copy. Most of the bad disks that I get come from disks that I am ripping for an Internet download service. When I get one that doesn't read properly it is usually because of scratches. About half the time these bad disks can be read on one of my three drives without any errors. At this point it is possible to burn a good CD-R copy. The drive that seems to do the best job on bad disks is old and slow. Perhaps it works well because it has seen very little use over its 10 year lifetime.
I don't like the idea of being captive to a CDP manufacturer for a working drive. I've been that route and had to junk an expensive player because of a defective laser that was uneconomical to repair. Drives wear out. The last time this happened on my audio PC it took me less than 15 minutes to install a new CD/DVD reader/burner which cost me less than $40.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I must be lucky but I've never had a CD fail, nor a CDR that I've made. And I've made many hundreds. I can't account for the problems people have with CDs (though I remember a Conrad Johnson transport/DAC combo back in the 90s that wouldn't play maybe 5% of my CDs; fortunately that's long gone). In the case of CDRs, though, I'm convinced that burning them at the slowest possible speed -- mine, via a Tascam CD recorder, are all at 1X -- is a good thing vrom a reliability/longevity perspective. I HAVE had CDRs that were made by others on their computers become coasters, but then I've never involved computers in the burning process myself.
I have yet to have a problem with a CD-R that I burned, including one that fell out of its jewel case and landed face down on a dirt road. Most of the problems that I've had were with CD-Rs burned by others (probably at high speed) and with pressed CDs that have been "pooched" by repeated mishandling. Recently, however, some unscratched CD's that I bought back in the 80's and early 90's have gone bad, including several titles in the "Compact Jazz" series. Probably some kind of rot. Is this the beginning of the end?
Please note that some of these CDs that have gone "bad" still play with no obvious audible degradation. The RBCD "error concealment" has simply interpolated the bad data and if there is not a lot of high frequency content or if the fault persists for a short period it is hard to notice the interpolation. One of my bad CDs would not rip without error correction turned off and then it had lots of pops and cracks. It sounded bad on my CDP in my car as well.
You are obviously taking good care of your CDs. Keep doing so and hopefully you won't have many problems. And definitely continue to burn CD-Rs at the best speed for the media and equipment. More important, back up any of these unreliable media before something goes wrong, rather than just placing blind trust in the technology.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I do keep waiting for one particular CDR to fail (and have backed it up just in case). I have no idea where I got it and it has no markings of any kind. Thing is, it's so transparent you can read a newspaper through it! But it soldiers on, so far at least.
"There is no way to intuitively understand issues related to the quality of data recorded on a disk or the performance of a disk drive in dealing with data errors. In particular, that fact that a disk plays well on a variety of players today does not mean that it won't suddenly deteriorate overnight. Similarly, the fact that a drive can play a bunch of damaged disks well does not mean that it will continue to do so, nor that it will play other damaged disks. This area is best treated as a "logic free zone"."
This is what I was getting at and I agree with that assessment. I am simply suggesting that since it is a logical error, that I could illustrate that. I understand from your perspective though how disproving poor logic does not satisfy the physics of the situation. The problem that I see posed is not that of a physical nature but of a logical one as there seems to be a debate of what might happen rather than of what is possible. I appreciate your insight.
-Bill
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