CDs: "Pressed" vs. "Burned"

This may be a technical question for another forum, but I thought I'd ask anyway due to the presence of some engineers here. I did a search and couldn't find a previous thread on this topic.

I've read somewhere that factory-made CDs are pressed and not burned, thus lending more longevity. I've also read somewhere that when we burn a CD-R or an exact copy, the inherent nature of the process yields a product with a shorter shelf life than a "pressed" CD. Is any of this true? I thought all factory-made CDs were in fact burned with an optical laser, just en masse and at a high rate of speed. Also, I have CDs that I burned 10-15 years ago that play just fine.

What are the differences in the industry manufacturing processes vs. computer / deck home burning, if any?

 

First: there is no reliable data or evidence that a burned CD-R has a shorter life-span than a manufactured CD.

Second: If there are any differences between the way a CD-R/CD is created, it's in the way it's formatted. It's mostly software dependent, and what the author does. Some CD recorders, mostly older ones or some consumer writers will insert a 2-second gap between tracks by default. Literally, this means the laser is turned off after each track. This is called Track-at-Once, or TAO recording, and is not really standard, but now somewhat acceptable to professional duplicators. The standard method is DAO, or Disc-at-once burning, and the author has the ability to insert a 2-second gap between tracks, but the laser stays on, allowing the disc to be written in one long spiral. The DAO method means there are fewer chances of errors created at the track transition points as in the TAO method.

There are lots of things that can be done on a computer that cannot be done on a stand-alone deck.

Sorry if I am not being clear, as I need some of what some people call "sleep".

 

I'm not an engineer either but I van tell you what I know about CDs compared to CD-Rs:

Pits on pressed CDs are shaped much more accurately than those created on CD-Rs by the burning laser beam. This caused issues with the error correction of older generation CD players and some of those refused to play CD-Rs at all.

The reflective layer of CD-Rs in which the pits are stored, is less stable over time than that of pressed CDs so basically, the pits of CD-Rs will fade quicker than those of pressed CDs. This is one part of their shorter shelf life.

Your older CD-Rs were burnt at slow speeds because older burners were not capable of burning at high speeds. Yet, my experience with data CD-Rs shows that pits burned at high speeds will be unreadable quicker than those burnt at low speeds, due to more reading errors with the quicker burnt CD-Rs.

So for saving data, I recommend burning CDs at low speed. Hence whenever I buy a music CD-R (which is only when there isn't any pressed CD available), I always burn a safety copy of it to store away at a dark place because you never know at which speed it was burnt.

I hope this helps.

 

Replicated CDs and DVDs (and, I assume, BluRays although I don't have first-hand knowledge as mycompany doesn't currently make BluRay discs) are manufactured in a process that is similar to injection molding. They are not burned with a laser like CD-Rs.

 

Do you have a source for this?

I have a handful of discs that won't play, but I'd estimate more than 99% of the CD-Rs I have play fine, some going back to 1998.

 

Always worth reading (this is a PDF file over 2MB)

http://www.genesisloudspeakers.com/whitepaper/Saga_of_the_Black_CDs_v3.1.pdf

 

I have some very old CD-Rs that play just fine (including the very first one I ever burned, in the mid-90s) and some that are just a couple of years old that give me problems.

It's pretty much impossible to know with any certainty the lifespan of a CD-R. There are simply too many variables, including (but not limited to) the quality of the media, the quality of the burner, the laser, the speed of the burn (and no one speed is the best, you need to find the correct speed for the specific media and drive you're using), how the discs are stored, possibly how often they are played, and so on.

I've been in the process of making sure I have lossless rips of anything I have on CD-R, so if/when any of them go bad I have a backup. (Eventually I will have a rip of every CD I own, but I'm definitely making sure the CD-Rs get done sooner than later as the failure rate on replicated discs is far less than CD-Rs.)

 

x2... and I'd be hard pressed to find one that doesn't play. I've got a few that have visibly "corroded" though, with the data layer looking like it's become oxidized and separating from the plastic. Obviously those won't play.

I've never had an issue with faster burned CD-R's.

 

I won't touch on most of that, but this is bogus:

Burning is one thing, but if you extract the correct data to your hard drive, it doesn't matter how it got there. If you have a good disc and a good drive, burst mode won't be any different than paranoid mode. If you extract a file two ways and the files are identical, but you think the paranoid extraction sounds better, the difference is in your head.

Also, Track Quality less than 100% doesn't mean the extraction wasn't 100% correct. From the FAQ:

 

Thanks. Pages 5 & 6 are interesting. I'm sure there's a more technical description of the manufacturing process out there, but this one is simple enough to grasp (assuming it's accurate).

 

I've also had mixed results and have CDRs going back to 1996 (!) and DVDRs probably going back to 2001 or 2002. Too many variables, as mentioned - disc manufacturer, burner itself, and the burning speed.

The general rule-of-thumb was always to burn at slower speeds if you wanted the disc to last a long time. But I'm not sure if that's really accurate or not. I also started using TY discs for my important DVDRs and, so far, I've had few failures over time.

 

I would like to hear Barrys input on this, I think he believes that burning at a very slow burn gives a far better sound than pressed. I bought the Equinox CD from him ((CD-R))and it is without a doubt the best sounding CD I have

 

Sorry, but I have a couple of rips done in burst mode from pressed cds which present continuous glitches and are almost unlistenable. All depends on the state of the disc surface when reading it. Audio players perform errors correction in real time, which is the reason we usually don't hear such errors when listening cds, but they are there and go to the copy, in which they appear as audible.
Secure modes in EAC have given me no problems so far. Paranoid mode is overkill.

 

Please re-read what I wrote:

In your case, with glitches, there were clearly problems (problems I'm guessing stem from poor DAE ability in the drive used for ripping). However, when there *aren't* problems, the mode used won't matter. That is to say, if the extraction is accurate, it doesn't matter what mode was used.

 

There are huge differences between a CD duplication (burnt) and replication (printed)
The burn is a surface scar
The print a physical pit.
Science dictates the longer life of a pit.

 

Just based on my personal experience living in a typically humid apartment for over a decade, I don't trust cd-rs. Some of my earliest burns are okay while many others no longer play. Some discs became prone to errors very quickly. Was it my burners' fault? The humidity in my storage environment? The manufacturer of the discs themselves? I don't know. I did have this problem across multiple burners and with a variety of brands of cd-rs (and dvd-rs/+rs as well), so who knows.

I've only had a few defective manufactured cds, and almost all of them were defective upon first play.

If you want to know more about the manufacture of cds, this rather lengthy article explains the details:

http://en.wikipedia.org/wiki/Compact_Disc_manufacturing

I wouldn't call that the equivalent process of a home-burned cd-r.

 

I have discs that I burned on a friend's company burner back when a 2X CD burner cost $1100 and blank discs were $5 each. Since that time, not one single disc that originally burned ok has gone bad. I've used mostly Verbatims, and unless a particular disc had problems during the burn process, not one of mine has had any issues playing or copying.
j

 

how to

yes, manufactureed cds are "pressed" from a master.

laser cuts a father into glass plate from course
a mother is created from father
a master plate is made from mother and used to melt metal material on and then coat in plastic

they do this steps so as master waers, a new one can be made form mother. if mother ever has an issue, they can make another mother from father. not requiring to go all the way back to laser

the cd-r are made kinda like the 1st step in manufaturing, but of course this pc based ones are no where near the factory ones. in the mid 1990s a laser machine was very very expensive and accurate and they cut into glass.

i would say the longevity is hard to state, due to the cd-r used and the qualsity of manufatured cd. look at the difference in 1st gen cds and now. 1st gen were thicker and harder. now they are very thin, you can see through them.

 

Thanks for the answers / input.

I make my safety copies with a Sony CD burner / player dual deck. I have noticed those discs sound better than EAC rips done on my computer. I always burn at 1x on the Sony.

 

Hi Stewart,

I'm not so sure about the longevity issue. I've not experienced any failures of CD-Rs when the blank is of high quality. My oldest date from 1990 (when the burner cost $15,000 and the blank cost $75 - my how time changes things ;-}) and still play fine.

Manufactured CDs are injection molded (not burned as one poster suggested - it is the glass master, used in the process of creating the "mother" for injection molding, that is burned).

Neither would I subscribe to the assertion that the pits on manufactured (i.e., molded) CDs are more accurately made than their equivalent on burned CD-Rs. In fact, I can think of why the opposite might be the case - with most glass masters today burned at high speed and the faster injection molding cycles.

My own experience with CD-Rs tells me the quality of the blank and the speed of the burn impact the audio. Not so much when the resulting disc is extracted to computer hard drive but when the disc is played in a CD player. To my ears, the faster burn speeds lose something, perhaps there is increased jitter or perhaps there is another reason.

Slow burns (on blanks of high quality that allow this) will, to my ears, sound more like the master from which they are made than even the best CD pressings. To be sure, the differences can be subtle in the best cases but often, they are not so subtle and the loss of focus and fine detail in the pressing can be quite obvious when one is used to listening to the master from which the pressing was made.

Whether this is related to the accuracy with which the pits on the pressing are formed, I don't know for sure. A typical pressing starts with a glass master which is cut at several times the actual playback speed and is created with an injection molding cycle of approximately 4 seconds duration. The best pressings I've heard have the glass cut in real time (i.e., 1x) and utilize a 9 second injection molding cycle.

A CD-R burned at high speed will, to my ears, lose much of the focus and fine detail lost in a typical pressing. One burned at a slow speed will preserve this information, even as at least some of it is lost on the very best pressings in my experience.

This is why Soundkeeper offers the option for CD-Rs to our customers. For playback in a CD player or transport, it is, in my experience, the closest one can get to the 16/44 master; closer even, than the very best pressings in my experience. Interestingly, as I mentioned above, if the audio is to be extracted for playback from a computer (assuming the computer files will be raw PCM, such as .aif or .wav), I have found no difference in the computer files extracted from a pressing vs. those extracted from a high quality CD-R. That is, I can null them against each other and I can null either against the master used to create the discs; they are identical.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

 

Barry as always a succicnt and well explain answer. Still waiting on your latest offerings. Now that I am back into Vinyl Soundkeeper Cd'S will be the only ones I buy. Have 700 Jazz titles (vinyl) to wade through should keep me busy for a while. Sorry for the thread crap

 

Hi laughalot,

Thank you for your kind comments.

Regarding the OT, you're on the mailing list, aren't you?
The next release is only a week or two away. (It contains tracks that might be the first "purist" recordings of all out electric rock. Other tracks are ballads or duets or trios - including one piano, cello, french horn song.)

The jazz quartet recording will be released in February or March.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

 

Only buy Taiyo Yuden CD-R and DVD-R discs if you care about quality media that will last over time.

Also burn slow although these days you don't need to burn at 1x (which is actually bad due to how the media is made).

I burn CD-R discs at 8x and DVD-R discs at 6x (if supported) or 4x if 6x isn't supported (once you go 8x or faster on a DVD the burning process changes to 'ramping' and that's bad).

 

Yep on th emailing list. Wait with bated breath and a ready CC