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Burning CD-ROM speeds

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by <--davor-->

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Hello folks

My friend and I have been discussng an issue about burning CD's. It seems that when you write a cd at high speed, the cd becomes more difficult to read. But I don't see why that should be. To me it seems that a written hole at 4X sameis as an written hole on 32x... is this true? I guess this problem must be related to the laser quality of the cd-reader?

If so what are then the best methods to write cd's?

Any arguments/suggestions are appreciated.
Thanks!

3 replies

by thechas

The quality of the CD blanks, and the CD-RW drive comes into play here.

The faster you spin the CD, the more it will wobble. If the wobble is large enough, and the drive does not constrain the CD sufficiently, the CD surface will move in and outof the focal point of the laser.

There was an article in one of the PC magazines that concluded that 16X drives were about the fastest you wanted to have for 'reliable' CD recordings.
At the time of the article, 16X Plextor drivers were actuallyselling for more than the newest high speed drives.

The article also pointed out an interesting conundrum for the situation.
Since the high speed drives are optimized for the higher speeds, they actually can make lower quality recordings when you force them to run slow!

Personally, I bought a couple of extra 12X drives, and plan to keep them as spares.

Chas

by <--davor-->

TheChas-->The article also pointed out an interesting conundrum for the situation.
Since the high speed drives are optimized for the higher speeds, they actually can make lower quality recordings when you force them to run slow!

When they say 'optimized' what exactly do they mean by that? I actualy don't understand the technical meaning of this.

And by the way, how can a Drive write a 'lower quality recording' is you said that the quality depends on the 'cd-quality'?

by thechas

There are many 'tricks' that can be used in both the electronics and the firmware of the drive to 'optimize' how the write process functions.

Characteristics such as the laser focus, pulse width, duty cycle, even data rates are adjusted to achieve specific performance levels at the highest burn speed of the drive.
On the mechanical side, the balancing of the CD platter, the torque of the drive motor, and the repeatability of the laser positioning system all change when you change the write speed.

Sometimes, adjusting the characteristics for high speed performance reduces performance to below specification at lower speeds.

I do not envy the CD burner engineers jobs in designing systems to work over a very wide performance range.
A good anolgy would be a Nascar or Formula 1 race car.
The cars work great at 150 - 200 MPH.
However, most could not make the average morning commute in 35 MPH traffic.

At a given write speed, the quality (not necessarily price) of the CD blank has the biggest impact on written CD quality for that drive.

Chas

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