Let’s see what happens at the moment of transitioning to the maximum burn speed in different cases. With enabled PoweRec the Beta graph shows distinctly how the laser power is diminished – the drive switches to the lower burn speed. The jitter rate goes down, too. If PoweRec is off, this part of the graph changes diametrically: the laser power (and the asymmetry, too) is increasing along with the jitter rate. But when we use a 16x blank, we have the following at the moment of 14x-16x transition: the laser power goes up (as you can see in the extreme part of the Beta graph), while the jitter rate doesn’t change with a jump, but steadily. At the end of the disc the jitter rate becomes just like at 14x. The burning layer of this disc is intended for 16x, and this fact explains why we don’t have a sudden variation of the jitter rate on it.

The results on the innermost tracks of the disc aren’t interesting, so let’s get straight to the middle where the jitter rate is good in all the three cases, but the maximum burn speed hasn’t yet been reached. Take a look at the quality of the disc on the outermost tracks – where the drive used 16x burn speed – the difference is apparent. The jitter rate of the 16x disc and of the 8x disc with enabled PoweRec is good (the Peak Shift value is smaller with the 16x blank, though), but the jitter of the 8x disc forcibly written at 16x is obviously bad. The drive doesn’t maintain the required pit/land lengths which the Peak Shift score is an illustration of – it equals 1.

So, what have we learned from these tests? First, the new model from Plextor produces discs of an excellent quality at the maximum speed, but you should use blanks specifically rated for this speed. And in any case you should not disable the PoweRec mechanism – the time gain of 6 seconds isn’t worth the considerably worsened quality of the disc. If the manufacturer introduces some new technology in its device, then it has some reasons for that – the PX-716A is a good example of this point.