What is worse than the “golden” wheels?
The prerequisites for the fact that the “golden” discs are worse than the “aluminum” ones are laid down in the recording technology itself. Standards for compact discs provide that the reflection of the laser beam from bright areas should be at least 70%.
Such requirements are met for stamped discs. However, recordable discs, unlike stamped discs, have an additional recording layer of organic polymer. This layer has limited transparency. Therefore, standards for recordable discs allow that reflection from highlights should be at least 65%.
Naturally, CD-ROM developers are not required to follow this assumption. Any working CD-ROM will read stamping well. But in cheap CD-ROM models, problems with recordable discs cannot be ruled out. To verify this fact, we took Bosch’s proprietary Service CD-ROM, made several copies on various devices and on various workpieces, and measured the reading speed of such copies on various CD-ROMs. Since CD-ROMs with different speeds were involved in the tests, further analysis was carried out not by the absolute speed value, but by the relative, relative to the speed value in this section for the reference disk.
The first conclusion we made is very trivial: if you take a good recording device, then on a good drive, recording on any workpiece will be read with almost the same quality as an “aluminum” disk. The recording was carried out on a Panasonic device, reading on the TEAC CD532E.
However, unfortunately, such an idyll is not always observed. In particular, Samsung’s most common low-cost CD-ROM model turned out to be very critical to the blank on which recording was performed (Fig. 3). All recordings were made on a Yamaha 4416 device.
It is clearly seen that on the final portion of the disc surface, the recording quality is significantly deteriorated. This is due to the complexity of the recording process itself. Recording requires a very high accuracy of maintaining the required laser power, precise alignment of the beam to the position on the disk and the distance from the laser to the disk. Obviously, on the edge of the disc, due to increased vibrations, it is much more difficult to fulfill all these requirements. But it is interesting that for the same recording device, errors appear differently for different workpieces. Therefore, in principle, if the recorded discs are hard to read, this can sometimes be eliminated by changing the type of blanks.
Unfortunately, the tests did not unambiguously determine the best or worst blanks. We did not come across bad workpieces. It’s just that all the blanks are different. For each type of recording device, you can select “favorites” on which the recording will be of higher quality. To a much greater extent, the reliability of the recording depends on the quality of the recording device. In particular, we compared the reading speed averaged over all recorded discs over a finite area of the surface. The averaging results are presented in Fig. 4. A value of 1 says that the disc is read no worse than “aluminum”.