I believe Jubeldum is referring to the change in color over emission angle seen on many Cree LEDs (AKA the Cree Rainbow), see posts #967 and #962 in this thread by LinusHofmann for a bit more on his pictures that demonstrates the effect rather clearly:
ECHO
Thanks Echo never heard that term before.
I hope that cop isn’t using an XHP70 in that small light. It would really burn up that poor kids mouth!
Looks like a nice emitter. Will anyone be offering these already mounted on copper MCPCBs any time soon?
The 50’s fit on a standard XM-L star, easy enough to set em up as you will. I have quite a few of the original SinkPAD in 20mm if that’d be any help to you.
Almost bought some, but did I read that correctly? F2 output bin?
I think the lower output bin coincides with the 90 CRI rating.
The F2 and F4 are the only 90 CRI options, with F4 being 50 lumens brighter at 700mA. Since we tend to push one much higher, then the difference is even greater. I don’t think I’d push one really hard if the 90 CRI was my option. On the other hand, if running an FET driver, it’s probably gonna pull quite high amperage due to the fact that it’s essentially a quad XP-G2. Limit that with something like a Panasonic BD and it’d probably be about right, optimized for output vs. tint binning. (2500-3000 Lumens?)
Or that would be my best guess anyway.
What would be a good regulated linear driver for the XHP50 and two 18650s? Are there other choices than a Qlite with Zener mod.? I expect to have a 20 mm. wide space in the pill.
Thanks finges, but that might be deeper than I can go at present. It really does look like an ideal driver, for both single and multiple die lights. I might try out the XHP50 first with a driver I already have or with no driver.
ok so ive pulled down my fandy fire xhp70 light that i got in the mail the other day, all the usual mods including a current bump to about 6.8A at the emitter (6.3V). on full power i get magic smoke from the emitter almost instantly and then the led starts to output a blue tint as it seems to get insanely hot. what puzzles me is that im only running 6.8A and it cant cope, its mounted to the standard alloy star with arctic silver5 thermal compound which is enough of a thermal path to sustain it for a while id think. is this just a dud LED or even may i say it, a copy XHP70. just seems odd to me because some of you guys are pushing the XHP70 Past 7A without issues and this one is crapping out.
there is the problem…. 
get a copper DTP MCPCB ant you will be happy
(IF the emitter did not get hurt permanently buy the overtemperature already…)
I think “then the led starts to output a blue tint as it seems to get insanely hot” its safe to say that LED is 4 square toast.
Angry Blue is very no bueno
hmmm. thought it may have been the issue, ill re-mount it to one of the sinkpad copper stars that i have and see if it makes a difference. I hope the led is not trashed yet as i dont let it get quite ’’blue”, i catch it as its shifting tint. if not ill replace the led as well and see how that goes…
well looks like the copper did the trick. The led was saved too which is a bonus 
. what is the largest copper star that i could mount the XHP70 to as the sinkpad ones a little small and foul the wires on the reflector base, i know i could stuff around with making copper tangs for the wires but it would just be a lot easier if someone made a star with a diameter of around 25mm or more for these, it surprises me that i cant find one seeing that the XHP70 is a large led typically found in large head flashlights with plenty of room for a larger star!
Um, as far as I know the XHP-70 doesn’t fit on an MT-G2 star. Wrong size footprint. The MK-R from SinkPAD and Cutter are the only ones I know of for it.
As a consolation I think that 25mm star would not offer that much over the 20mm one. Certainly it would be better, but by the time the heat has flowed to the edges of the 25mm star, it is already on its way in a big way into the aluminum pill.
The closer to the LED you have copper, the greater the benefit.
Now having said that, if there is a 25mm copper star, I want one
dchomak, the idea was to spread out the contacts to clear his reflector. More copper couldn’t hurt, of course, but some lights have too flat a base on the reflector, like the HD2010 which is legendary for this problem.
As usual, I didn’t read his post carefully enough.
Yeah, the HD2010, I found out the hard way :_(
Luckily, on start up with the driver I had, it went into moonlight and all I blew was the 7135