CDs vs CD-Rs

[fr8nks]

This a a quote from Amphissa:


Various independent research studies have been showing for years that CD-R technology is not the equal of commercial CDs. The latest I'm aware of is research by the Dutch folks at PC-Active. My Dutch sux, so I'm going on the translations of others. Apparently, they tested 30 brands of CD-R media. What they found was that a large percentage of the discs were unreadable in total or in part within 20 months.

Here is a summary in English:
http://www.cdfreaks.com/news/6450-CD-Recordable-discs-unreadable-in-less-than-two-years.html

Here is the original Dutch article:
http://www.pc-active.nl/component/content/article/10508

Based on previous research, the reasons for degradation are varied.

1. The laser in typical home CD player/burner is not nearly as powerful as the lasers used to burn commercial CDs. CED/DVD player/burners vary in quality. Most people just buy the cheapest they can find, or settle for whatever is in the computer they buy (which is usually the cheapest the builder can get).

2. Much of the software used for burning CDs does not verify the burn - i.e., it does not do a read step that verifies that what has been burned coincides with the original data. Even if using software that will do this step, many people just don't enable this feature.

3. CD-R media (blank discs) vary tremendously in quality. Brand name is not a good guide for selecting media. There are two major manufacturing plants for blanks. Companies contract with them for product. A few companies require highest quality media only, and cost more as a result. Most companies go for the mass assembly line discs, which are not up to the highest levels of quality.

4. Storage makes a difference. Store burned disks in heat or brightly lit areas or expose them to tobacco smoke - that's just adding to the environmental factors that can hasten degradation. Some discs just degrade with age - the material itself degenerates - even under optimal conditions.

To reduce the risks of degradation of CD-Rs (and DVD-Rs) --

1. Use a high-quality burner, like a top of the line Plextor, and verify burns to assure that the burned data coincides with the original.

2. Use high quality blank discs - top of the line Taiyo Yuden or top of the line Verbatim (which are made by Taiyo Yuden).

3. Store burned discs at cool room temp, relatively low humidity, out of bright light.

4. Retain a digital backup in a lossless format, like FLAC or AIFF, on a hard drive, and copy to newer hard drives every few years.

CD and DVD technology is not a reliable long-term archival solution. Even with all these precautions, about 10% of discs will suffer some degradation over the course of 2-5 years. Some will not read/play at all. Others will have portions of the disc go unreadable, so even if the disc starts, portions may not play.

Of course, if the CD/DVD is just for convenience and replacement is available, all the precautions are less necessary.


______________________________________

Here is another point of view:

According to Robert Harley in the September, 2007 issue of "The Absolute Sound" magazine CD edge treatments that purport to reduce the reflected laser light have more effect on a commercial stamped CD than on CD-Rs because less light is reflected to a CD-R's edges by its concave pits than by the convex pits of a CD. That may be one of the reasons that a CD-R copy of a commercial CD frequently sounds better than the original CD.

Another reason CD-Rs sound better is that the center hole of a commercial CD is stamped after the data is embedded onto the CD and the center hole may not be perfectly centered. As a result the CD player's tracking servos have to work harder than if the disc was perfectly centered. A CD-R already has its center hole cut before it is burned.

The final reason given as to why a CD-R sounds better than a commercial CD is a standard CD burner inverts the polarity of the music on the copy relative to the original CD. And because most CD players also invert the polarity, this is a great sonic and musical improvement for the CD-R relative to the original CD since most CDs are recorded in the correct polarity.

A renowned audiophile entered the Meridian Audio room and was listening to a new CD player with a commercial CD on its transport. Then after a minute the original CD was replaced with a CD-R. The audiophile expert exclaimed, "That's impossible!" The second disc's sound was much better.

[Alan Howe]

Just an observation from my experience:

1. My carefully stored and handled CD-Rs last well, with hardly a failure at all.

2. The CD-Rs I use in the car degrade fast.

Ergo: it's all down to storage and handling.

[semloh]

Interesting! I always buy TDK or Verbatim in bulk - most other brands not being recognised by my successive Dell computers - and over a period of 10 years I've probably had two discs fail, out of - I guess - at least 2000, despite the very hot, humid climate. And, many have been stored on spindles rather than in individual trays.  I also have thousands of commercial CDs, purchased over a 20 year period - and not a single failure despite transportation across the continent, climatic changes, etc.  So, I certainly have no complaints! 

Do the reviewers' comments apply equally to DVD discs?

[fr8nks]

Interesting! I always buy TDK or Verbatim in bulk - most other brands not being recognised by my successive Dell computers - and over a period of 10 years I've probably had two discs fail, out of - I guess - at least 2000, despite the very hot, humid climate. And, many have been stored on spindles rather than in individual trays.  I also have thousands of commercial CDs, purchased over a 20 year period - and not a single failure despite transportation across the continent, climatic changes, etc.  So, I certainly have no complaints! 

Do the reviewers' comments apply equally to DVD discs?

DVDs were not addressed in the article. Most of the DVD copying programs I have seen compress the video to fit on a 2 hour DVD so the quality is reduced although I can't see the difference. In order to copy a DVD without loss requires expensive blank media. I can buy a 120 minute blank DVD for about 20 cents where an 8.5 GB blank disc costs around $1.50.

[nigelkeay]

This a a quote from Amphissa:
The final reason given as to why a CD-R sounds better than a commercial CD is a standard CD burner inverts the polarity of the music on the copy relative to the original CD. And because most CD players also invert the polarity, this is a great sonic and musical improvement for the CD-R relative to the original CD since most CDs are recorded in the correct polarity.

To me there seems something rather odd about this statement. By polarity I take it that we are talking about "invert phase". If the burner inverts the phase, and most CD players (whatever "most" means) also invert the phase, then the player is simply going to invert back to the original phase, no?

Invert phase can be useful to check whether what's burnt onto a CD-R is the same as the original source by importing the audio from the CD-R back into a DAW, then inverting its phase and playing simultaneously with the original. If it's an exact copy the result should be absolute silence. 

[fr8nks]

This a a quote from Amphissa:
The final reason given as to why a CD-R sounds better than a commercial CD is a standard CD burner inverts the polarity of the music on the copy relative to the original CD. And because most CD players also invert the polarity, this is a great sonic and musical improvement for the CD-R relative to the original CD since most CDs are recorded in the correct polarity.

To me there seems something rather odd about this statement. By polarity I take it that we are talking about "invert phase". If the burner inverts the phase, and most CD players (whatever "most" means) also invert the phase, then the player is simply going to invert back to the original phase, no?

Invert phase can be useful to check whether what's burnt onto a CD-R is the same as the original source by importing the audio from the CD-R back into a DAW, then inverting its phase and playing simultaneously with the original. If it's an exact copy the result should be absolute silence.

Phase and polarity are often confused but they are not the same. To answer your question the player (not all) inverts the polarity of a commercial CD. A copy of a commercial CD is inverted by the burner. Thus when it is played it is back to the original polarity.

[nigelkeay]

Phase and polarity are often confused but they are not the same.

I'm not too surprised that they are often confused; I used "invert phase" because that's what the function that flips the polarity on the DAW that I use is called. I read through an article that I felt clarified things rather well. In my mind, in my original post, I was thinking of invert polarity so the second paragraph still stands if "invert polarity" replaces "invert phase".

[markniew]

Few years ago I experienced problem with the Hawk label (a kind of no-name one, I know). Almost all CDRs burnt during let say month got completely ruined and useless, unplayable. The same happened to my friend at the same time.

Other problem was when I used to keep my CDRs (of good label) in plastic color envelopes. Recordable sides of many of them got in reaction with plastic that resulted in stains that made recordings demaged. Those one where the paper inlays (with descriptions) were placed between the recorded side and the envelope did not suffered. 

I believe that majority of other CDRs burnt by myself are in good state. However to know it exactly I would have to check all of them but it takes so much time that I do not expect I do it 

[fr8nks]

There was a problem reported in 1994 that first appeared in American Record Guide Magazine of CD bronzing. It was a form of rotting that eventually made the CDs unplayable. The problem affected several labels and was traced to a production plant in the U.K. If the letters PDO appeared in the fine printing around the center hole of a commercial CD, it was at risk of deteriorating. If you owned one or more of these CDs, they were replaced free of all charges including shipping and handling by sending an email to an individual whose address was posted in several articles. The discs were replaced without questioning but the jewel boxes and liner notes were not included. I had about 22 CDs that contained the letters PDO on them and new ones were sent to me in the United States without questions and free of charge and without returning the originals. I have seen CD bronzing on certain labels of CD-Rs that were stored in high heat for several weeks but the manufacturers have disclaimers exempting them from liability.

Warning!!!  If you have a CD that is turning brown, make a copy of it before it is too late.