> But isn't the whole point the CRI, CRI is a point as is CCT (2800k specified). I hate 2800k compared to higher temperature colours. 5600k is fine by me. Thy seem to think people want to live in Tungsten lit rooms. I'd rather live in daylight like lit rooms. My LEDs have a CCT of about 6000k and a CRI of low (have to check report but was under 70 I think). BUT it's a lovely shade - most people like it and it has a nice "feel". Whatever. > the form factor Cree seem to have allowed themselves to dispense with conventional form factor. A choice I approve of. I've been thinking along those lines just recently. > and the cost? I don't think they mentioned cost :-). > After > all I'm sure they could get significantly higher lm/W if they used > twice as many cold white LEDs and decreased the power supplied to > each. They are limited to the CCT specified by the advanced standard. And they may have used more LEDs run at low % of output to achieve what they did. Or not. > Personally I'm impressed we're still seeing significant advances > - not like we'll ever again have the overnight 100% increase in > efficiency when the XR-E was released. That was only a quantum leap wrt prior offerings they had. My 3+ year old Nichias are still up wit XR-E's when derated. But at a very small fraction of the power !. (100 mW/LED) > How would you handle cooling with your 100 LED array? I'm guessing > it's not something you have to worry about too much with a single LED > running at ~30mA. One LED is "not hard" - although you do actually see the difference between 1 LED done well and 3 of the same done stupidly by a factory when you weren't looking against explicit instructions to the contrary and then formally tested over 2000 hours by an important certifying authority :-). Fortunately the sheer brilliance of the LED (pun almost unintended) is more than a match for the stupidity of the factory. The 1 LED improves in output by 1 to 2 % over 2000 hours. The 3 identical LEDS drop by a fraction of a % over 2000 hours. The latter result would be highly acceptable if it were not for what could have been done. LEDs are 100 mW and 7mm on a side . If you stack them (example only) on say 7.5mm grid a square array =3D 75mm x 75mm =3D 3" square. You then have 10 Watts to dissipate less the not insignificant light radiation :-) - small portion but actually noticeable. Take a single prepreg layer (0.25mm) and copper to suit and laminate onto finned block of Aluminum of your choosing. A few degrees C per Watt will be acceptable. Fan blow if challenge is too hard. Else convection/radiation cool with eg liquid filling to get heat out onto an outer surface or heat pipe or ... if you wish. ie it's not conceptually hard - just a matter of finding some existing engineering method that works for you. I have several hundred of these LEDs. One day ... ;-). Russell McMahon Applied technology ltd. New Zealand. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .