# High vs Low CRI led comparisons?



## jeffkrol (Jun 5, 2013)

Kessils go from 6000k to 9000k no evidence of any diodes of lower k than 6000..
As to CRI, or any stats really.. Kessil is "mum"..









nothing spells high CRI in the above GIF

you can make things look really good w/ low CRI but you will not make them "natural"..
There is a difference//


ADDING RGB to make white is Horribly low in CRI..


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## ChrisX (May 28, 2017)

Has anyone here built a DIY fixture with high-end whites exclusively? Every DIY build I've seen is with color mixing.


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## jeffkrol (Jun 5, 2013)

This is w/ 4000k Luminous Devices 95 plus CRI (royal blue pump) COBS and and one 95 plus CRI Sorra violet based pump COB (needed to disassemle a light , they don't sell loose chips)
Link for large file:

Anyways one point is photos aren't always the best indicator of what "you" see.
Think about your home incandescent.. Nothing looks as "yellow" as it photographs.
Point is Devil is in the details..
Luminous Devices makes a "set" of high CRI LED COBS under the "studio" variety..
http://www.luminus.com/products/Luminus_XNOVA_Studio_ProductBrief.pdf


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## ChrisX (May 28, 2017)

jeffkrol said:


> This is w/ 4000k Luminous Devices 95 plus CRI (royal blue pump) COBS and and one 95 plus CRI Sorra violet based pump COB (needed to disassemle a light , they don't sell loose chips)
> Link for large file:
> 
> Anyways one point is photos aren't always the best indicator of what "you" see.
> ...


Cool. You're right, photos don't tell the whole story.

I'm pricing out higher CRI leds and they are almost cost prohibitive. Good Leds are 4-10$/ea. Cost for 60 leds.. $300-$600. I think when you are spending that much it better be clear that they are worth it.

Luxeon Rebels are 1.50/led from overseas (3.00 stateside), but its an 80 CRI, maybe not even from good bin, might be high-70s. While these are "affordable" its not clear how much of an advantage they are.

The cheap Epis, who knows what CRI they are, but they are .50 ea.

I think I will go ahead with my custom RGB light (to add color) as opposed to upgrading to better whites. Can "lime" leds be a replacement for green in an RGB array?


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## jeffkrol (Jun 5, 2013)

If you want one "color" go COBS...
$13.85 for 36W......... 78Lumens/watt

https://www.digikey.com/products/en?mpart=CVM-14-56-95-36-AC00-F2-2&v=1214
$1.15/ 3 watts..
Luminus Studio LED series offers production class lighting solutions designed for high performance illumination applications. The selection covers a wide lumen range from less than 400lm to over 10,000lm, both color temperatures and can deliver color rendering greater than 95 at 3000K and 5600K. These breakthroughs allow illumination engineers and designers to develop no-excuses lighting solutions offering the brightness and overall quality of conventional lamps.

Bridgelux vero "decor" are cheaper..


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## ChrisX (May 28, 2017)

jeffkrol said:


> If you want one "color" go COBS...
> $13.85 for 36W......... 78Lumens/watt
> 
> https://www.digikey.com/products/en?mpart=CVM-14-56-95-36-AC00-F2-2&v=1214
> ...


Those cobs must be blindingly bright and create spotlights. Are they really applicable for aquarium use?


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## jeffkrol (Jun 5, 2013)

ChrisX said:


> Those cobs must be blindingly bright and create spotlights. Are they really applicable for aquarium use?


Thats whats on the tank I posted.. Well Luminous Devices. There 95 plus but not the Studio version. Just as good though.. 

Bare COBS are usually "lensed" around 120 degrees..

Technically they should be raised a bit...........

COBS were about $70 total..though slightly inflated since I had to buy a light and disassemble it. About 2x more than it should have cost..
but that was only one out of 5
They are all run low though.. none at over 400mA


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## ChrisX (May 28, 2017)

jeffkrol said:


> Thats whats on the tank I posted.. Well Luminous Devices. There 95 plus but not the Studio version. Just as good though..
> 
> Bare COBS are usually "lensed" around 120 degrees..
> 
> ...


When I started my DIY light I did not know of those, but I don't think it would have changed my design. What I keep coming back to is that all the commercial products are built to a price point and are unlikely to be using high-CRI leds. Yet in the right combinations they look quite good. 

I have designed and will be building adjustable R G B channels. 12x 3W each color, 36 x 3W total to supplement the 60 x 3W white leds. This will add $50 to the build but will be worth more than upgrading whites to a higher CRI. 

Having experimented with different colors of white, the best look is between the correct balance of cold and natural light.

The "final" version of my DIY light will be when I upgrade the white lights to dimmable drivers. There will be five total channels (cold white, natural white, red, green, blue) that can be controlled by a TC-420. All for < $200.

What is the maximum wattage per channel that a TC-420 can handle? I may just keep dimmable controls analog.


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## jeffkrol (Jun 5, 2013)

4A though apparently some have exceeded that..
At one point I had the spec sheet of the MOSFET inside and believe it was 4A @ DC (continuous on at 100%)

If you modify it like I have shown in the past and use it to control LDD's there is sort of no "maximum" 
The 5V "digital out" and the low current needs of the LDD...

Current available at the gate hasn't been measured..
Pretty sure each channel can run multiple LDD dim circuits..Limit is unknown.


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## Xiaozhuang (Feb 15, 2012)

I'll have to say CRI can be deceptive... if you have a fixture that produces high contrast red/blues for example, highlighting those tones; you can have a low CRI but have quite good color tones in the tank. For example, the fixture lighting this tank is only CRI 78


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## jeffkrol (Jun 5, 2013)

Your color temp is 3605K.. just pointing it out..

and yes lower CRI tanks can be brilliant..but it isn't "exactly" natural..

It IS a matter of opinion more than a matter of good vs bad..
In a white room it would look warm toned..

IF they calculated CRI correctly (based off d50 since K temp is below 5000k) at D65 it's even lower.. like 57............
Using 2856K "Standard" light source it would be around 90CRI.. 

SO TECHNICALLY you DO have a high CRI light..
Just not in reference to daylight.. 

*Anyways beautiful tank..*

One thing I "assume" .. any light w/ greater than 90CRI and a color temp greater than 5000k will have naturally pleasing real color.. 
Whether one want to enhance or underplay a part. color is personal choice..

I went on a high CRI kick because every white LED I tested was lacking and the only way to correct it was colored diodes..
The fact that we now actually do have choices in high k and high CRI diodes is a blessing.. 


More for fun.........


> CIE standard illuminant A is intended to represent typical, domestic, tungsten-filament lighting. Its relative spectral power distribution is that of a Planckian radiator at a temperature of approximately 2856 K
> Illuminants B and C are easily achieved daylight simulations. They modify Illuminant A by using liquid filters. B served as a representative of noon sunlight, with a correlated color temperature (CCT) of 4874 K, while C represented average day light with a CCT of 6774 K.
> 
> Why 6504 K?
> ...


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## Surf (Jun 13, 2017)

> Has anyone ever done a direct comparison between high-CRI whites like Cree and low (cheep) CRI leds? I would like to learn if the difference in "look" is because of spectrum, or because of CRI.


I have looked at the data sheets on Cree and other LEDs and you can find in those the spectrum for the low and high CRI LEDs. The most obvious difference between low and High CRI LEDs is the amount of red in the spectrum. Low CRI have a minimum wavelength of 630nm with is the read that humans see most easily. Plants prefer deeper reads of about 640 and 660. High CRI meds typically have more of the deeper reds. There are other subtle changes in yellow and green that are probably hard to make out on the spectrum charts. 



> Has anyone here built a DIY fixture with high-end whites exclusively? Every DIY build I've seen is with color mixing.


I have made a lam using 12VDC high CRI (90+) LED strips. The light works well. Prior to this I used 80CRI LED bulbs. The difference between 80 and 90 is not a lot and I didn't see any big changes but I believe there is bit more color in the fish and plants. If I compared RGB bulbs to the new lamp I am sure I would have seen a big difference. The main reason i made the new light was however to get more light for my pants. Many modern LED and CFL bulbs didn't fit the old tank hood. That a limited me to low light plants.


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## jeffkrol (Jun 5, 2013)

Surf said:


> I have looked at the data sheets on Cree and other LEDs and you can find in those the spectrum for the low and high CRI LEDs. The most obvious difference between low and High CRI LEDs is the amount of red in the spectrum. Low CRI have a minimum wavelength of 630nm with is the read that humans see most easily. Plants prefer deeper reads of about 640 and 660. High CRI meds typically have more of the deeper reds. There are other subtle changes in yellow and green that are probably hard to make out on the spectrum charts.
> 
> 
> 
> I have made a lam using 12VDC high CRI (90+) LED strips. The light works well. Prior to this I used 80CRI LED bulbs. The difference between 80 and 90 is not a lot and I didn't see any big changes but I believe there is bit more color in the fish and plants. If I compared RGB bulbs to the new lamp I am sure I would have seen a big difference. The main reason i made the new light was however to get more light for my pants. Many modern LED and CFL bulbs didn't fit the old tank hood. That a limited me to low light plants.


Check out these spectrums..









There are other big differences..

http://www.plantedtank.net/forums/10-lighting/1101618-new-custom-leds-making.html
http://www.open-photonics.com/featured-technologies/high-cri-leds
This too..









Note the boost in cyan range..
And why would one care?
Plant green shades cover the gamut.. 
some low CRI led's make all plants look "the same"..
ADMITTED, it is subtle and not a PRIORITY for most..but makes a difference.









One more spectrum
http://www.open-photonics.com/wp-content/uploads/2014/03/OPI-Ultra-High-CRI-LED-data-sheets.pdf


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## ChrisX (May 28, 2017)

Is there a phone app to measure spectrum?


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## jeffkrol (Jun 5, 2013)

ChrisX said:


> Is there a phone app to measure spectrum?


No.. 
But Seneye attempts it..
A "real" spectrophotometer" is quite pricey..

One more for fun............
http://www.ledlightsinindia.com/information/choose-best-quality-led-lights


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## navarro1950 (Jul 25, 2014)

What would LEDs rated at 3 watts be considered ? Green Element has this fixture. 


Sent from my iPad using Tapatalk


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## jeffkrol (Jun 5, 2013)

navarro1950 said:


> What would LEDs rated at 3 watts be considered ? Green Element has this fixture.
> 
> 
> Sent from my iPad using Tapatalk


CRI is spectrum dependent. Doesn't depend on power output.
If referring to the 6500k model (link probably removed) that only tells you how warm or cool the light is,,
6500k being one of the "close to daylight" color temps..
Lights that are 6500k can have any CRI value..
Don't suspect it is very high w/ the Green Element diodes..and will probably differ lot to lot..
There claim to fame is a lot of power for a low cost..
Plants want photons w/ little caring what "color" they are..


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