# XM-L vs XM-L2 neutral spectrum quite different



## bbb74 (May 21, 2013)

Looking at the spectrum charts for the XM-L vs the XM-L2, I've noticed the XM-L2 is quite different particularly for the neutral (3700-5000K) range. Somebody pointed this out in another thread and nobody really noticed so I thought I'd ask about it in its own thread.

XM-L sheet: http://www.cree.com/~/media/Files/C...d Modules/XLamp/Data and Binning/XLampXML.pdf
XM-L2 sheet: http://www.cree.com/~/media/Files/C... Modules/XLamp/Data and Binning/XLampXML2.pdf

Cool:


Peak red/orange output drops from 50 to 40% relative power, they're otherwise pretty similar

"Neutral white":

Peak red/orange output drops from 70% to 50% of relative output
Peak deep red (~650nm) output drops from 40% to 20% of relative output
The dip around aqua drops from 16% to 10% of relative power
Peak blue output is more or less the same wavelenth of cool, instead of being maybe 10nm warmer on the xm-l

"Warm white":

Peak blue output drops from 65% to 36% of relative output
Deep red drops from 68% to 60% of relative output

The biggest difference is for the neutral whites. The XP-G2, XP-G, and XM-L neutrals look very different to the XM-L2 (more red/orange output vs blue output, relatively speaking).

I'm wondering if the XM-L2 spec sheet result for neutral is a mistake or they measured at a different part of the neutral range (3700-5000K for Cree)?

Also I'm wondering how the "neutral" XM-L2's can really be neutral compared to XM-L, XP-G[2] if their red/orange/yellow output is that much lower. 

Scratching my head here...


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## SemiMan (May 21, 2013)

Yes, Cree stated that they had optimized the phosphors for higher output (LER) without sacrificing CRI.

Semiman


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## bbb74 (May 21, 2013)

SemiMan said:


> Yes, Cree stated that they had optimized the phosphors for higher output (LER) without sacrificing CRI.
> 
> Semiman



I wasn't really asking about CRI here though. The XM-L2 neutrals seem like they would not be neutral compared to XM-L if going by the spec sheet graphs. Much less orange&red output vs blue, they are closer to the cool range.


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## SemiMan (May 21, 2013)

bbb74 said:


> I wasn't really asking about CRI here though. The XM-L2 neutrals seem like they would not be neutral compared to XM-L if going by the spec sheet graphs. Much less orange&red output vs blue, they are closer to the cool range.



It's a very rough graph of a very large CCT range.

They have adjusted the phosphors for higher photopic output .... without making color rendering worse.

They are going to be just as "neutral" as that is mainly a factor of CCT ... which you are specifying when you buy the product.

Semiman


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## pepperdust (May 24, 2013)

I have CW / NW / WW in XM-L2, and CW/NW in XM-L

the NW (Xm-L2 ) is "NW" looking ...




I thought this funny also, and find is very odd that the next 'version' ( XM-L2 ) is completely different in spectrum, and not just "power" then the brother (xm-l )


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## AnAppleSnail (May 24, 2013)

That could easily be sample to sample variation. Cree's color bins are often big enough to drive a truck through, not to mention the 'temperature' buckets.


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## bdiddle (May 25, 2013)

I don't have many NW led's, but I do have an XML2 T6 3C, and an XML T6 4C.

The XML2 3C has more yellow than the XML 4C, and the 4C appears to have more red.

And the XML2 is a good bit brighter.


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## AnAppleSnail (May 25, 2013)

bdiddle said:


> I don't have many NW led's, but I do have an XML2 T6 3C, and an XML T6 4C.
> 
> The XML2 3C has more yellow than the XML 4C, and the 4C appears to have more red.
> 
> And the XML2 is a good bit brighter.



That's to be expected, since the 4C tint bin is a redder one than 3C. See the ANSI tint bins CREE inc uses. And the XML2 is on average 2 bins higher output (14%) than a "same bin" XML-1 because the output binning was changed (25C test to 85C test).


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## Jenni13 (May 31, 2013)

hi, 


if we can get each data point for the spectrum then we can calculate the color point 
for these 2 product. but based on CCT 3500K to 5000K, the delta u'v' is already 0.03, this is
quite huge range. so this is acceptably that their spectrum vary for these 2 products, but still within 3500-5000k, just these 2 parts color different is visible, since ANSI guideline is 0.007. 

the best Cree can support for Delta u'v' is i think 0.002 to 0.004 for their other product. 

hope i answer you.


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