Rollitup

Thank you for the heads up, that SPD looks great!

Unfortunately we do not know the LER or QER for the 3500K and 4000K 80 CRi CD, so we cannot estimate and compare their efficiency accurately. But generally speaking, their efficiency should be about the same, 61% @ 35.5W (1050mA).

The 4000K 70 CRi DB should be higher efficiency, my spreadsheet returns 66.3% @ 35.5W (1050mA)

Or are you referring to 72V class?

I was referring to the 36v.
4000k 70 CRi @ 66.3% sounds real nice.
I've been lurking on the led forum some time now and Im thinking of trying a build, been getting into arduinos and so this could all jive really well. A few questions about some light specs for ya.

First, I would like to design a light to cover a 4ft x4ft area, with at least 18 par/w per sq ft and with between 750-850 PPFD over the entire canopy. I would like to use 4000k 70CRi CXB 3590 DB bin, 36v at 1050 ma for 66.3% efficiency with KB reflectors (LEDIL mimics). What is the optimal number and spacing pattern of CXB, and at what height from canopy would work best?

I also would like to add some red spectrum to adjust the blended spectrum of the COB and red LED to 3500k without hopefully hurting efficiency more than a point or two. IDK, i think 660nm is the way to go. Could you tell me which 660nm(?)LEDs to use , and how many, driven at whatever current works out best. What would be the efficiency of such a light then?

what would be the cost for something like this using active cooling? maybe passive cooling, but cost and weight matter to me as I'd be building 4-6 LED fixtures

did I actually make sense with all the that?
Happy New Year Supra!

Happy New Year! So 18 PAR W/ft² puts you around 875 PPFD averaged. One example that would get you there, (3) HLG-185H-C1050s with 5 CXB3590s on each.

I agree the KB reflectors look very promising and I plan on doing some testing with them, hopefully comparing against the LEDIL and also modifying them with the best performing reflector paint that I have found so far (Rustoleum High Heat White 7751830)

The best deep reds are probably Oslon SSL80 Hyper red, because of their 80 degree-ish beam pattern and relatively high efficiency, especially if you can get the 4T bin. Unfortunately the efficiency is far short of the 3590 so it will drag your system efficiency down but it can partially make up for that with a higher photon count (5.48 vs 4.55) and more photosynthetically active, as well as rounding out the spectrum.

To put that example in another perspective, the cost of SSL80 @ 700mA = 1.67W @ 43% = 2.34 umol/J cost $2.83/PAR W.

If you were willing to pay $2.64/PAR W you could get: CXB3590 4000K BD @ 700mA = 23W @ 69.3% = 3.13 umol/J.

That is such a large difference in photon count (34% more) there is no way the spectral improvement could make up for that. So for thos who want to tweak and maximize their lamps, the most effective you possible is to run big COBs soft.