DiY LED Vegging - Cree XM-L2 VS Cree CXA3070

SupraSPL

SupraSPL

Well-Known Member
Fasttech just made these available on stars for cheap. Cree XM-L2 U2 4C. They are 4250-4500K. The U2 bin is really cranking out photons and this is the first I have seen it in neutral white, up to 172 lumens/W. I think these would do a fine job vegging on their own but would be even better with some red/deep reds added. As awesome as COBs are, the XM-L2 does allow for more flexibility to spread the light across a wider space.

XM-L2 4C U2 efficiency:
XM-L2 4C U2 bin.png



Not that there is anything wrong with Vegging with COBs. You could make a custom reflector and keep them higher above the canopy. Here is the efficiency chart for the 4000K and 5000K bins that we currently have available from Digikey.
CXA3070 4000K vs 5000K.png
 
K

kakamika

Member
Thanks for the info Supra!

The efficiency chart of the XML2 is great! going to order of few of these just to play around with. they just might make it into my final design :D

The amount of information on this forum is truely amazing when it comes to high-end DiY led discussions.
 
D

dude9000

Member
I noticed you use warmer colors for veg. Is there a reason? I'm used to using t5s suplimented with cfls at 6400 for veg.. I've used warmer colors in a pinch and really notice better results with 5000< for veg.. I know LED is a little different and looking through the threads it seems like everyone wants to half ass it with a one light solution for veg and flower. That's no fun.
I really like your builds and built my own similar to yours.. Only using vero18s at 5000 instead of the crees. Haven't tested them yet though. Looking to play around with the spectrum a little to see what gives the most explosive growth for veg. Maybe add smaller red/blue LEDs in the mix? Then I'll worry about flower with a new build. Suplimenting hps and slowly kick the old school hot ass bulbs out of the room for good!
 
SupraSPL

SupraSPL

Well-Known Member
kakamika I did the same thing ordered a few to mess around with. Off topic, I use XM-L2 T5 5B1 4200K in my headlamps. The 4500K U2 should be a significant step up and I would have to change batteries less often.

dude9000 we used to use 6500K LEDs (I still have some in service that need updating) but that was primarily because warm whites were so bad in those days. Now it seems like the phosphors have improved so much that we can get high efficiency in the 4500K range. The way I see it the warmer the whites have more of their output in the red range instead of the green/yellow range, which should improve photosynthetic efficiency of the spectrum but still providing enough blue to control stretch. KNNA recommended 25-30% blue (PAR Watts) for vegging lamps.

Example vegging lamp: (4) Cree XM-L2 U2 4500K + (1) Luxeon ES deep red EX6, both on the same string. That would give us 24% blue with an overall radiometric efficiency of 48.5% if run at 650-700mA.

Small improvements in efficiency make huge differences to a vegging room. I have a vegging box for rooted clones and seedlings with just 1 XM-L2 T6 4500K running at 650mA (about 2W). It is about 2 sq ft and the ladies in there love it. I suspect they could grow faster if I added more light but I am in no rush because I have to stay on pace with the flower rooms in a perpetual.
 
D

dude9000

Member
2w for the baby girls sounds great. Especially without having to make room for a buky fixture. I like the fact that LEDs are not only efficient with electricity but also space, especially if you design your own light.
So in theory adding more than 30% blue in veg is pretty much a waste? Do LEDs in the cooler spectrums give off more in the green/yellow range or are you talking about older LEDs?
Really what I'm wondering is, adding red and maybe deep red to my vero18 setup would be more beneficial than adding more blue?
Thanks!
 
SupraSPL

SupraSPL

Well-Known Member
You are correct, cooler LEDs have their peaks shifted toward the blue. So 2700K has a peak near 630nm red and plenty of output in the 660 deep red range. 3000K has a peak near 610 and plenty of output in the 630nm red range but low in the deep red. 5000K has decent output in 630nm but misses the 660 deep red.

Mr Flux was nice enough to run the calculus and his math says that Vero 5000k is 22% blue. He also normalized these Vero curves so they are relative to each other. From looking at this, it seems like the low hanging fruit is to add deep red but as you do your blue percentage drops.
View attachment 3006643

For those who are interested here is the Cree CXA normalized curve
View attachment 3006642
 
hyroot

hyroot

Well-Known Member
Supra what's your thoughts on cri?. Some say a little lower with more red is better. From the induction and CMH standpoint I see having higher cri (more even spectral distribution) has better results. Regardless of par being high or low. The iG's hit 800 umole/s at 18 inches and cri is around 90. From an led standpoint it seems running a bit lower may be beneficial. I hope that made sense
 
SupraSPL

SupraSPL

Well-Known Member
In the earlier days of LED growing, KNNA was a promoter of photons (efficiency) over spectral distribution and I have always been on board with that. I have seen excellent results (bud quality and yield) from narrow peaky LED spectra like this: deep blue, cool white, 630nm red. I do believe it is ideal to spread the spectrum where possible but not if it requires a significant sacrifice of photons/watt. As you can see from the charts above, the high CRI LEDs suffer a very significant penalty even though their SPD looks very good. I believe we will achieve much better results (than High CRI LED) by simply adding high efficiency deep reds or even just by running 3000K on its own.

------------------------

Regarding induction for vegging, I apologize to any indagrow owners if this seems harsh, I am evaluating induction by indagrow's provided data. Induction vs diy LED for vegging, here are my concerns:

-efficiency - not surprisingly, induction's radiometric efficiency is similar to fluorescent tubes. Indagrow claims 60 lumens/watt even on their most efficient lamp and they are short on deep red so spectrum is no excuse for low lumen numbers. That translates to roughly 20%. diy LED can be up to 48.5% (using Cree's minimum figures).
-directionality - induction outputs in 360 degrees versus LED 115 degrees. Despite their claims, Indagrow suffers a very significant reflector penalty. Only a small proportion of its photons are heading in the right direction, and they are not that cooperative when trying to redirect them to the canopy.
-flexibility. with LED I can spread the light where I need it, even in chunks as small as 2W. The height of each heatsink is adjustable if needed.
-spectrum - Induction has high cri but despite that it is still lacking in deep red
-price. Indagrow smallest lamp cost $5/W versus diy LED $2-4/W
-lumen depreciation - Indagrow claims 7% loss in first 2 years VS 1-2% for properly cooled LED.

OK so I am no fan of induction, but I have not tried growing with it or High CRI LED or CMH, so my advice is only valid on paper and I am open to all possibilities.
 
hyroot

hyroot

Well-Known Member
The spectrum chart on the inda gro site is for the old 400 which they no longer sell. The 420 has more deep red. Daryll and Chaz have both told me the site is getting updated soon with up to date spd's. I can say its the best light for vegging so far. I'm just starting to veg with a51 sgs 160. So we'll see. For flowering with induction I got denser buds and more trichome development than CMH, hps, par t5 and Chinese led. The a51 I have is the first quality led to compare. I got a pretty good yield with smaller plants too.

with induction I have seen great results with higher cri / lower par. I was very skeptical going in with low par numbers. I had great results despite a few issues and a learning curve with the way plants grow and feed more frequent and light distance.

I'm slowly building up the room still. One side already induction. The other side all led. I still plan on following your build for veg led lights.
 
PetFlora

PetFlora

Well-Known Member
Wow. Invaluable 411

hyroot said:
The spectrum chart on the inda gro site is for the old 400 which they no longer sell. The 420 has more deep red. Daryll and Chaz have both told me the site is getting updated soon with up to date spd's. I can say its the best light for vegging so far. I'm just starting to veg with a51 sgs 160. So we'll see. For flowering with induction I got denser buds and more trichome development than CMH, hps, par t5 and Chinese led. The a51 I have is the first quality led to compare. I got a pretty good yield with smaller plants too.

with induction I have seen great results with higher cri / lower par. I was very skeptical going in with low par numbers. I had great results despite a few issues and a learning curve with the way plants grow and feed more frequent and light distance.

I'm slowly building up the room still. One side already induction. The other side all led. I still plan on following your build for veg led lights.
Click to expand...
 
PetFlora

PetFlora

Well-Known Member
+/- 3000K seems to be the budding ticket, at least with my sats

I have posted this 2 yo info before "

As one can see, the CREE Neutral White (I call it 'Goldilocks', because it's almost 'just right' ) has a RSPD that still allows nearly ~25% of its total power in the blue range (and plants only really 'need' ~8-10%), and more that 1/3 of which (i.e. the area under the curve) is over ~580nm or so (which has a Photosynthetic RS of over 90%!) - which is much better than even your typical 'Enhanced HPS'.

Couple that with strong white light (green-response chlorophyll extending throughout and deep into leaf structures, with a net effect at or near that of the (mostly) surface-level blue and reds), which also takes care of most of the ~660nm+ you actually need for photomorphogenesis - and you can get by with 630nm reds just fine.

(i.e. 630nm red is ~95% of the PSR of 660nm, AND they currently still have ~20-30% greater radiometric efficiency - as well as being cheaper than the deep reds - so there's more 'bang for the buck'):


SupraSPL said:
In the earlier days of LED growing, KNNA was a promoter of photons (efficiency) over spectral distribution and I have always been on board with that. I have seen excellent results (bud quality and yield) from narrow peaky LED spectra like this: deep blue, cool white, 630nm red. I do believe it is ideal to spread the spectrum where possible but not if it requires a significant sacrifice of photons/watt. As you can see from the charts above, the high CRI LEDs suffer a very significant penalty even though their SPD looks very good. I believe we will achieve much better results (than High CRI LED) by simply adding high efficiency deep reds or even just by running 3000K on its own.

------------------------

Regarding induction for vegging, I apologize to any indagrow owners if this seems harsh, I am evaluating induction by indagrow's provided data. Induction vs diy LED for vegging, here are my concerns:

-efficiency - not surprisingly, induction's radiometric efficiency is similar to fluorescent tubes. Indagrow claims 60 lumens/watt even on their most efficient lamp and they are short on deep red so spectrum is no excuse for low lumen numbers. That translates to roughly 20%. diy LED can be up to 48.5% (using Cree's minimum figures).
-directionality - induction outputs in 360 degrees versus LED 115 degrees. Despite their claims, Indagrow suffers a very significant reflector penalty. Only a small proportion of its photons are heading in the right direction, and they are not that cooperative when trying to redirect them to the canopy.
-flexibility. with LED I can spread the light where I need it, even in chunks as small as 2W. The height of each heatsink is adjustable if needed.
-spectrum - Induction has high cri but despite that it is still lacking in deep red
-price. Indagrow smallest lamp cost $5/W versus diy LED $2-4/W
-lumen depreciation - Indagrow claims 7% loss in first 2 years VS 1-2% for properly cooled LED.

OK so I am no fan of induction, but I have not tried growing with it or High CRI LED or CMH, so my advice is only valid on paper and I am open to all possibilities.
Click to expand...
 
SupraSPL

SupraSPL

Well-Known Member
hyroot said:
The spectrum chart on the inda gro site is for the old 400 which they no longer sell. The 420 has more deep red. Daryll and Chaz have both told me the site is getting updated soon with up to date spd's. I can say its the best light for vegging so far. I'm just starting to veg with a51 sgs 160. So we'll see. For flowering with induction I got denser buds and more trichome development than CMH, hps, par t5 and Chinese led. The a51 I have is the first quality led to compare. I got a pretty good yield with smaller plants too.

with induction I have seen great results with higher cri / lower par. I was very skeptical going in with low par numbers. I had great results despite a few issues and a learning curve with the way plants grow and feed more frequent and light distance.

I'm slowly building up the room still. One side already induction. The other side all led. I still plan on following your build for veg led lights.
Click to expand...
I am glad to hear you are getting good buds :weed: and it will be interesting to see how the A51 does vs the induction.
 
DiyKindaGuy

DiyKindaGuy

Active Member
Hello everybody... ive been floating around the forums and kinda really made my week catching up on a couple hundred or maybe a couple thousands pages of journals and chit chat.. my point being i love what some of yu have done with the cobs but i havent seen anybody mention the cree multichip on ebay such as the pics i uploaded.. now by visual inspection these multichips look rough or rugged compared to the thinner looking cobs... i dont know what thickness difference between the two are or what is more efficient but i would need a data chart for the cree xpg the xml and few other multichips.. i my self got in the led game two years ago when i bought some expensive 300watt panels... i believe they were like $600 each... anyways thats when i got hooked... so long story i no longer have those 300watt panels so ive made a few small ones of my own but now im wanting to get the bigger chips 100watt to 300watt maybe one day do the 500watt chip i saw on ebay lol kinda get excited thinkin bout running big chips... so anyways i currently own 1 watt and i burnt out all my 3 watt but have ten watt chips and my first 100 watt cool white i planned on vegging with i know they are chinese no name but they are good for a beginner like me.. i did a price comparison between drivin top bin and low bin and the watt/$$ adds up quick... i have four kids and my gf so i cant be investing thousands into leds anyways thank you everybody for all the information it saves us time and money keep it buddin everyone!!!

&#9733;&#9733;&#9733;kushed_out&#9733;&#9733;&#9733;
 

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DiyKindaGuy

DiyKindaGuy

Active Member
Hello everybody... ive been floating around the forums and kinda really made my week catching up on a couple hundred or maybe a couple thousands pages of journals and chit chat.. my point being i love what some of yu have done with the cobs but i havent seen anybody mention the cree multichip on ebay such as the pics i uploaded.. now by visual inspection these multichips look rough or rugged compared to the thinner looking cobs... i dont know what thickness difference between the two are or what is more efficient but i would need a data chart for the cree xpg the xml and few other multichips.. i my self got in the led game two years ago when i bought some expensive 300watt panels... i believe they were like $600 each... anyways thats when i got hooked... so long story i no longer have those 300watt panels so ive made a few small ones of my own but now im wanting to get the bigger chips 100watt to 300watt maybe one day do the 500watt chip i saw on ebay lol kinda get excited thinkin bout running big chips... so anyways i currently own 1 watt and i burnt out all my 3 watt but have ten watt chips and my first 100 watt cool white i planned on vegging with i know they are chinese no name but they are good for a beginner like me.. i did a price comparison between drivin top bin and low bin and the watt/$$ adds up quick... i have four kids and my gf so i cant be investing thousands into leds anyways thank you everybody for all the information it saves us time and money keep it buddin everyone!!!

&#9733;&#9733;&#9733;kushed_out&#9733;&#9733;&#9733;
 
DiyKindaGuy

DiyKindaGuy

Active Member
Wow how did it resend with out pics.. weird sorry i dont know why

&#9733;&#9733;&#9733;kushed_out&#9733;&#9733;&#9733;
 
DiyKindaGuy

DiyKindaGuy

Active Member
Its weird i have no idea but im hoping some one sees my post cause im wondering whos running those ebay chips and what are their results

&#9733;&#9733;&#9733;kushed_out&#9733;&#9733;&#9733;
 
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