<a href=showthread.php?s=&postid=15328865#post15328865 target=_blank>Originally posted</a> by der_wille_zur_macht
The first and last link you posted are, in theory, the same exact thing - a Q5 bin Cree XR-E on a star. The middle link you posted is an R2 bin, which is the next level up in brightness.
Cree bins their cool white XR-E with a two part bin code. One part indicates brightness, in terms of lumens/watt. That's the part most of us concentrate on. It's more or less a sequential number - Q2, Q3, Q4, Q5, then they jumped to R2. Each increasing bin gets a few more lumens per watt, which means more light in your tank for the same amount of electricity.
The R2's are extremely rare (hard to get) hence not many people in this thread have used them. If you look through the comments on that item on DX, you'll see that in the past, plenty of people have ordered them thinking they were in stock, only to wait months before getting them.
The second part of the bin code indicates a color code. "cool white" is a generic label; they further designate color by a two letter code. Cree calls this the "chromacity or dominant wavelength group."
WG is by far the most common, though a few vendors are selling WC. WG is spot in the middle of the range. It's interesting that ledsupply.com does NOT tell us the color bin, but they do tell us the kit number, which means we can look up a list of color bins it *could* be. The list happens to be WC, WD, WF, and WG. These are all OK and pretty close to eachother. FWIW, despite being labeled as "cool white" they are all pretty warm compared to the stuff we are used to in the reefkeeping hobby, which is likely the reason why so many of these LED builds are using a 1:1 ratio of "cool white" to blue.
I am trying to leave a blob on the leftover pieces that the LED's were attached too, they are the same material as the pads. I tin the gun, press it to the pad, wait about 10 sec or so and try to add solder, it just won't melt! It's a 45W solder gun.
