DiY LED - Cree CXA3070

Positivity

Positivity

Well-Known Member
Either a long and skinny 4' heatsink with stars...or one of the fancy cob types http://www.led-tech.de/en/High-Power-LEDs-Osram/Osram-Modules/12-x-OSRAM-Oslon-SSL-80-red-on-round-pcb-LT-2035_206_209.html

To do that nice cdm justice I wouldn't use anything but osram or Philips. The cob type would be my pick, nice built in 80* lens...probably at least 4 of them to start. Add as needed..

could make a nice and easy DIY out of a long heatsink. Just mount the driver and fan on top with a power cord. 3 of the 4' heatsinks with 3 cobs apiece or stars would cover it completely I'd think. Pretty big area to cover with leds nicely..

Not really aware of any commercially available high quality 660nm lights

Some ideas..
 
RedCarpetMatches

RedCarpetMatches

Well-Known Member
Positivity said:
Either a long and skinny 4' heatsink with stars...or one of the fancy cob types http://www.led-tech.de/en/High-Power-LEDs-Osram/Osram-Modules/12-x-OSRAM-Oslon-SSL-80-red-on-round-pcb-LT-2035_206_209.html

To do that nice cdm justice I wouldn't use anything but osram or Philips. The cob type would be my pick, nice built in 80* lens...probably at least 4 of them to start. Add as needed..

could make a nice and easy DIY out of a long heatsink. Just mount the driver and fan on top with a power cord. 3 of the 4' heatsinks with 3 cobs apiece or stars would cover it completely I'd think. Pretty big area to cover with leds nicely..

Not really aware of any commercially available high quality 660nm lights

Some ideas..
Click to expand...
Thanks for reply. I agree on the long heatsinks ;) Wouldn't need much for some spread out 660 Luxeons (which are quality enough I believe)
 
SupraSPL

SupraSPL

Well-Known Member
Good questions CB. The Z2 in a 95 CRI would be incredible if we were talking about the CXA3070, but in the case of a CXA3590 a good performance group would be BD which is 5 groups above the Z2. So basically that means the high CRI has a relatively low radiometric efficiency.

Regarding high CRI vs high efficiency, I am in the camp that high efficiency is the way to go. I am also interested in growing the very highest quality bud, but I do not believe high-CRI LED or CMH will result in higher quality bud than 3000K 80 CRI or 3000K + deep red and deep blue. That is just my suspicion, I have not done a side by side. I am making that judgement based on the fact that I have never come across any outdoor bud that has outgunned my indoor LED bud.
 
SupraSPL

SupraSPL

Well-Known Member
RedCarpetMatches said:
Supe/other spectral geniuses,

This is my current spd with the 860w CDM
View attachment 3037849

I would like to supplement this with perhaps more 660nm? I have a 5 x 5 bare vert with around 12" behind plants. I can go above, behind, or a little both with the supplementing LEDs. With the limited 'back' space in vert...would you guys just go with stars or ram em with cobs?

Think I've asked this before and never received an answer. Any advice would be appreciated!
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The spectrum is pretty nice. You could supplemement with 630s, 660s or both. I have always thought it might be tricky to use LEds to supplement HID because the LED heatsinks would block the CMH if they are in tight to the canopy, so maybe the Oslon SSL80 would be a good choice because the tighter beam would allow you to get some distance from the canopy?
 
SupraSPL

SupraSPL

Well-Known Member
Unfortunately not, I have one on order to test. I expect it to put out much less than 1500mA once it is warmed up but we'll see.
 
Bueno Time

Bueno Time

Well-Known Member
SupraSPL said:
Unfortunately not, I have one on order to test. I expect it to put out much less than 1500mA once it is warmed up but we'll see.
Click to expand...
Thats cool you have one ordered. Im sure you will do a thorough evaluation of the driver. If it turns out good, it would be a good cheaper option for a 1400mA driver.
 
Abiqua

Abiqua

Well-Known Member
SupraSPL said:
Good questions CB. The Z2 in a 95 CRI would be incredible if we were talking about the CXA3070, but in the case of a CXA3590 a good performance group would be BD which is 5 groups above the Z2. So basically that means the high CRI has a relatively low radiometric efficiency.

Regarding high CRI vs high efficiency, I am in the camp that high efficiency is the way to go. I am also interested in growing the very highest quality bud, but I do not believe high-CRI LED or CMH will result in higher quality bud than 3000K 80 CRI or 3000K + deep red and deep blue. That is just my suspision, I have not done a side by side. I am making that judgement based on the fact that I have never come across any outdoor bud that has outgunned my indoor LED bud.
Click to expand...

CRI is indeed fool's gold and has inherent bias towards 14 colors, not exactly a "full spectrum". There are real problems, especially with High CRI, which is absolutely no guarantee that color rendering is optimal.
http://cie2.nist.gov/TC1-69/2.Problems of CRI -Ohno.pdf
 
FranJan

FranJan

Well-Known Member
^^^Bingo, though I wouldn't say "Fool's Gold" as much as "Slippery Slope". Probably important for induction, it can be good and bad for white LEDs IMO, (see PICO's COB grow and CREE's less than optimal for growing High CRI bulb for good and bad high CRI examples respectfully). It's pretty good for monos but more for a quality or performance indicator, (from what I've read), since their CRIs are much lower, but higher than average can indicate a wider spectrum, (if you want that), and/or good Tj junction performance, (See Lenks' "Designing LED..." for more on that stuff).

It's just a matter of time till they come out with the new ways of quantifying LEDs, like R96a, which we'll then argue about :). Bottom line it's a Photometric rating, right?, and that has limited value in our world I think. Best use it as just another indicator of a LED's potential performance, and not as a "Seal of Approval" IMHO. Peace.
 
C

CannaBare

Well-Known Member
Abiqua said:
CRI is indeed fool's gold and has inherent bias towards 14 colors, not exactly a "full spectrum". There are real problems, especially with High CRI, which is absolutely no guarantee that color rendering is optimal.
http://cie2.nist.gov/TC1-69/2.Problems of CRI -Ohno.pdf
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Great! Which means I'm back to watching the 3000k till harvest before my next led purchase! :) Thanks for the great answer Supra and the study Abiqua!
 
SupraSPL

SupraSPL

Well-Known Member
My four oldest modules have polished heatsinks but I built those before I realized how bad the aluminum stars were. So I have been replacing those modules with these. Upgraded the 3000K XTEs to 3000K CXA3070s at 900mA and added 140mm fan for active cooling. They will dissipate 85W each and run at 42% efficient with 15% blue output. I will flatten the remaining Luxeon ES stars and reuse them later.

DSC07092a.jpg
 
C

CannaBare

Well-Known Member
SupraSPL said:
My four oldest modules have polished heatsinks but I built those before I realized how bad the aluminum stars were. So I have been replacing those modules with these. Upgraded the 3000K XTEs to 3000K CXA3070s at 900mA and added 140mm fan for active cooling. They will dissipate 85W each and run at 42% efficient with 15% blue output. I will flatten the remaining Luxeon ES stars and reuse them later.

View attachment 3038893
Click to expand...
Are you holding those cxa's with only tape and thermal grease?
 
SupraSPL

SupraSPL

Well-Known Member
Yes that is correct. It is Prolimatech PK2 and kapton tape. I could use the COB holders but Newark is a PITA to order from and I don't want to drill the surface of my heatsinks because I am always changing the design.

The tape is not necessary just a precaution, the paste acts like a glue once it dries. It is more to keep the LEDs from moving around before dry. The power leads are zip tied to relieve tension.

It is not pretty but I am more concerned with efficiency than looks. In the CREE CXA design guide PDF they show the difference in performance with a variety of thermal pastes/pads/glues of varying thickness and surface roughness of the heatsink. The Prolimatech performs better than the best paste in the PDF (11.2 W/m• °C) It does not make a huge difference but I'll take a few degrees anywere I can.

Thermal paste.jpg

Thermal paste 2.jpg
 
PetFlora

PetFlora

Well-Known Member
I suspected the adhesive interface leaves a lot to be desired efficiency wise

Just one of the reasons holding me back from DIY

Don't COB holders also need to be glued, or do they come with an adhesive pad?
 
SNEAKYp

SNEAKYp

Well-Known Member
Yea my molex holders just popped on right on top of the COB with some artic silver, a 3/8" drill bit, and some #4-40 screws it's all set. It's nice to not have to solder on to the COBs with these.
 
Observe & Report

Observe & Report

Well-Known Member
What's that old joke about the US vs. Russian space programs? NASA spent millions designing special COB holders while the Russians just put a couple of holes in the plastic COB frame. ;-) I'm being the class clown, of course, but buying holders does eat into the efficiency advantage offered by Cree CXA. I wonder if you can drill into the frame on 3070's without hitting anything important?
 
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