AFAIK the main factor is based on manufacturer. I don't know the best one off hand, I think LG's are good???? But check that out on here. Use the search
As for the x16-x20 speeds, it *should* be the same type of diode, just of a higher power (hence faster burning) but there is probably an exception to this.
So the faster the write speed, the higher the diode power!
yeas most likely
the 20x will be an open can and the 16x will be a closed can, basically covered with a little window whereas the 20x it just open without a cover or anything, very fragile
20x open cans are usually better for burning, and get less hot as most of the heat is given off
because its open
If you are brand new to harvesting diodes, I strongly suggest you stay away from open can diodes. They are much more sensitive than closed cans. Very difficult to work with IMO.
Most of the heat from the LDs in burners is conducted away rather than radiated. The open heatsink LDs in DVD burners are installed in sealed enclosures so the airflow is minimal.
As was mentioned, usually the faster drives require a higher power LD because the time the data location us "under the gun" is less with higer speed units. Therefore, more heat must be applied to get the same effect.
I've got a team of people working on this project that includes a laser. I'm sure I can find some ECE or EE people to carefully do this for me. If I follow all the instructions very carefully.... I should be fine right ^_^
I just want to add I do not believe there is any difference in any of the open can diodes used in DVD burners. If you want to try an open can I suggest the Pioneer PL-112D burner as I think it is the easiest to harvest. If you want a 16X diode, then there are still a few left in the GB. Look in the Buy/Sell section of the forum.