CDR Speed Ratings

[superJess]

I know that what speed a CDR will burn successfully relies heavily on your burner, computer, and the brand of disc. My question is more general - what makes one CDR rated at a different speed than another? What is the physical characteristic that the manufacturer changed (if anything) to say "this one is a 32X CDR" and "this one is a 48X CDR." Does that make sense? Does it have something to do with the type of dye? I've been curious about this for a long time and I'm having trouble narrowing down search results on the web to come up with a place that details these types of things.

Thanks for any insight you can provide!

[dhc014]

I think that it has more to do with the strength of the polymers (plastic) used to make the disk, and any method used. The dye has a part in it as well, but mostly, the speed rating is based on how high of a rotation speed the disk is meant to handle.

[dodecahedron]

i have to disagree.

while i'm not speaking with any authority or any official knowledge, i feel that the strength of the polycarbonate plastic of which the CDR is made is not the issue. after all, many are reading 12x rated CDRs on new drives at 52x and "exploding" CD occurences aren't that common.

i believe it has to do with the dye.

e.g. Verbatim/Mitsubishi media: up to 16x they used Metal Azo, with newer and faster media they switched to Super Azo. my conclusion: the Metal Azo couldn't handle being written at faster speeds.

probably has to do with the fact that when burning at a higher speed, the laser has "less time" to burn the "pits" onto the CDR, the chemical reaction of the dye due to the laser heat has to be quicker.

[cfitz]

I agree with dodecahedron.

cfitz

[rdgrimes]

One rather large factor in the ability of a CDR to be writable and readable at high speed is the consistancy of both the stamper (disc) and the dye layer. At 48x-52x they have to be nearly perfect. That is, a perfectly flat disc with a perfectly even dye later. I read somewhere that making a perfectly flat stamper is the main thing that is limiting CDR makers from producing higher-speed discs. Not that they can't make them better, it's just too expensive to make them better. cfitz, you remember the colored Fuji media problems I was having, the visable unreadable area on the discs were very consistant with a "ripple" in the stamper or dye layer. Whether that "ripple" occured before, during, or after the disc being manufactured is anybody's guess.
It's my understanding that the stamper (disc) is made separately from the CDR mfg process.

[superJess]

Thanks for the explanations ... it makes sense to me. Though I would think there aren't any real differences between smaller hops - say a disc rated for 24X and a disc rated for 32X - besides the label on the package. But that makes sense because if they didn't have a 32X burner to test on they couldn't rate it that high yet. I guess I shouldn't assume that because the manufacturer now claims it's a 32X disc they're claiming they did something different to make it so. Again, I appreciate the help.

[Inertia]

HIGH SPEED CD-R DEMANDS NOT ONLY THE CHANGE IN STAMPER, DYE AND COATING BUT ALSO A TIGHTER MANUFACTURING PROCESS QUALITY WINDOW.

See the detailed explanation of the technology involved in high speed CD-R manufacturing at THE STORY BEHIND 48X SPEED CD-R.

[cfitz]

Great link, Inertia! Thank you for sharing it. There is a lot of interesting information there. I will bookmark that site.

cfitz

[CDRecorder]

That was an interesting article, Inertia! Thanks for posting it. I bookmarked it, too.

[kilahchris]

great post , my question is though what about drives who are unable to burn at the optimal speeds on certain medias?

for example I have 40X verbatim CDRW DRIVE this is able to burn 48X Sony Media at the drive's optimal, speed.
However my brother has a 32x Nesi (no name) burner that can only burn the same exact sony media (from the spindle) at 16x speed?

In this situtation what is the physcial differences that limit his CDRW Drive or if the media is to blame how ?

[CDRecorder]

The "problem" is probably the drive's firmware. The firmware contains information about which media can be burned at which speeds.

One drive's firmware says that the discs can be burned at only 16x.

The other drive's firmware says that the discs can be burned at 40x.

[TheWizard]

It could also be the quality of the drive. Nesi? Never heard of it. It's reliability seems shoddy.