When trying to clone protected cd's it can sometimes be better to read the source (original) cd at the lowest speed possible.
Though i want to know why this is.
On normal cd's :
How do you gain more errors just because you used a higher speed ? Are we talking physics here or is there some timing process in the internal of the cd-reader that cannot keep up with some errors ?
If it can't read them , some error check routine has to take place and they just start reading that sector AGAIN. (Same as harddisk of floppy method). The usual error control would be : Try to read it again. So it doesn't really matter whether you use 1 speed or 72 speed to read a cd-rom. The retries get more and more perhaps of the psychical aspect (cd stretches , gets warm , etc)
On protected cd's (deviation of red/yellow book) :
Still.. how do you gain more errors ? The errors are there of course , it's part of the protection scheme , but why would a higher speed get you more errors. Next to the physical aspect there are fixed errors. But these fixed errors are known. It of course depends of the protection method , but the errors are known and thus the place of the errors can be known.
So in this case you could get to read it at 72 speed and just skip the "imprinted" error sectors and still have the same data you used to have.
Tricky thing of course is you can't possibly know on forehand if an error is imprinted (fixed (intended) error) or some dust particle (accidental error). But this could be done by perhaps reading the source cd several times , store all these images seperately and bit by bit compare the various images. The accidental errors may wander around the image of the cd but the fixed errors would stay in place. But you still could read the source cd continously on 72 speed. No need to set in on 1 speed.