CD Players (2/2)
Some people would think that the information transfer rate is directly proportional to the number before the 'X'. However, this not true. They may think that a 12X drive would transfer information at 12 times the speed of a 1X drive. They would think that installation times would also be inversely proportional. With a standard CLV drive, the numeral behind the X represents the theoretical optimum information transfer rate. So a 12X drive would have 12 * 150 kb/s = 1.8 Mb/s transfer rate. This value, however, is only theoretical. Other factors come into play such as the command overhead, the interface speed, etc. The information transfer rate definitely improves with a faster drive, but hardly in a linear fashion.
In the case of CAV drives, you cannot even figure out the speed using the X! Since the drive spins at a constant rate throughout, there is less information in the middle and the most at the outermost edges. A 24X drive is only 24X at the edge, and performance can suffer as much as 60% when reading the middle. The data is also recorded from inside to outside, so if the disc is only half full, the transfer rate would come nowhere near the stated 24X speed. The only advantage these drives have is a smooth and silent data transfer.