CREE CXB - Why do the Better Bins have lower CRI?

I am trying to understand the data sheets for COBS.

To my knowledge the higher bins usually result in the cob having better CRI and higher lumen count.

However the official cree spec sheet at cree seems to say otherwise.

Better Bins are listed with Lower CRI (80), whilst the worse bins are listed with the Higher CRI (90+)

Here is a picture to prove it \/\/ww#s21.postimg#org/e71z5jy1j/cri_vs_bin.png

What am I misunderstanding here?

Lower CRI = higher lumens / watt but more green light which may not be as beneficial to plant growth. Hence the saying 'lumens are for humans'...

Might be further ahead trying to understand what CRI actually is before you try to understand how it effects COBs.

Or perhaps a better question is, how you plan on incorporating this information into your purchasing decisions? Because you will find tons of conflicting information detailing how each is better than the other, typically with little or no empirical evidence to back it up.

thetr33man said:

Lower CRI = higher lumens / watt but more green light which may not be as beneficial to plant growth. Hence the saying 'lumens are for humans'...

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I thought the CRI was a scale used to indicate how close the spectrum was to its listed Kelvin, that must be where I am wrong.

Shugglet said:

Or perhaps a better question is, how you plan on incorporating this information into your purchasing decisions? Because you will find tons of conflicting information detailing how each is better than the other, typically with little or no empirical evidence to back it up.

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I plan on using it to make a better decision, other than data sheets and others experiements what else do we actually have?
and your right, I have found tons of conflicting information.

Just look the graphs in the data sheets for a specific cob. It will show you a good visual of the differences. 90cri usually has a red peak around 630nm where 80 cri peaks closer to 600nm...

thetr33man said:

Just look the graphs in the data sheets for a specific cob. It will show you a good visual of the differences. 90cri usually has a red peak around 630nm where 80 cri peaks closer to 600nm...

Click to expand...

Hey, thanks for pointing that out, indeed the graphs match the peaks you mentioned...

What would you say is the better CRI to choose...? I have checked over the data sheets and can see that some even feature CRI 70...(adds to the complexity) - Surely at some point lowering the CRI so much would result in a LED far from what its supposed to be?

I grow with 90cri personally. A lot of people are happy with 80 tho... Ive seen a few comparison grows that seem to indicate better results with 90. Also might have something to do with grow style. If you are going to have a thick canopy, the green light produced by lower cri may penetrate better in to lower/inside branches giving them a better chance to develop than a higher cri cob would. Just and idea but it hasnt been proven that I know of yet.

Rahz has shown the difference, I would recommend checking it out. Its called something like CRI Test.