I am trying to understand what causes variability in the color temperature of white LEDs.
I recently got some white LED strip lighting and it was sold to me as having a color temperature of 3000K. I also have some overhead LED downlights that were of the recessed bulb type and they also are supposed to be 3000K.
I used a high-quality spectrometer to measure the color temperature of all the lights. I found that the down lights varied from 3000 by about +/- 50K. Also, if I measured the same light multiple times I got a variation of +/- 5k, which I guess is the limit of precision for the instrument. The down lights where never less than 2975K or more than 3080K.
The LED strip, however, was a completely different story. Depending on where I measured on the strip it varied anywhere from 3200K to over 3400K. If I measured in the same spot, I got the same +/- 5k, just like the overhead lights. Why would the strip be so much more variable? Also, how do they control the color temperature of the manufactured LED in the first place?