Why are new drives slower?



I just upgraded from an artec cd-rw drive to an NEC 4551a.
There are 2 cd speeds of each drive of the same disc (a cd-rw, burnt as a cd-rom, no udf or anything). Why does the old drive reach faster speeds? The NEC is locked at 40x, is there a way to unlock it?

My old cd writer treated the cd-rw as if it were a cd-rom (read it at the same speeds), however the NEC treats it differently.

Also why are most drives limited to 48x? My cd-rom has a max speed of 52x…?

What gives?


The reason for the 48-52x limit is the rotation speed, 9000+ RPM. Faster than 9000 RPM rotation runs the risk of cracking and breaking the polycarbonate that the CDs and DVDs are made of.

CD-RW are read at slightly slower RPMs because they have lower reflectivity and are likely to slow down when read at 48x at the outer edge.

Finally, some manufacturers are a little more conservative than others. The difference between 40x P-CAV and 48x CAV reading is probably within 20 seconds, no big deal, especially in a DVD burner.