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How can you be sure you aren't being shafted by 2 dollar 50W cobs from aliexpress/ebay? Either factory rejects, can't take the rated wattage for too long or just plain fake data. Also the "50W measured flux map" is clearly a 5000K LED. And a CXB3590 at 5000K goes up to the DD bin at 70 cri...

Leggy Stocky. Here is mine, tomato is coming soon. The third image doesn't really do justice how thick the stem already is. A lot of branches without pruning/topping, top is already producing flowers. Sides are starting to show their first. Fan cord is a bit unyieldy, but this is just a...

Thermal paste tranfers heat better than air. So unless both aluminium surfaces are completely flat (not going to happen), thermal paste helps with better heat transfer. Always try to have it as thin as possible because it only needs to fill the airgaps.

130lm/w should be system efficiency so it's not that bad. If it is also with the lenses factored in it's decent. Seems rather overpriced though.

This is why single die LEDs will probably always have an advantage for mass production over COBs. Machines can assemble LEDs on a PCB much faster than a cob can be drilled into a heatsink.

Then they are yet to be released to the major distributors.

Maybe you're talking about the 1206 http://ce.citizen.co.jp/productse/info.php?no=116 Or maybe since efficiency is somewhat predictable they have put in a hypothetical 1216 in the simulator.

Growing with HPS for the UV-B is a bit useless. That's like drinking Cola for vitamin C. Just get an Agromax fluorescent

Luminous efficacy is how well a light produces visible light. Which is determined not just by how well the source produces light but also how well the emitted light is detected by the human eye. It's for humans, and just humans. A XTE Royal Blue at 0.35A puts out up to 575mw of radiant flux...

It's grown under nothing but 2700K when I'm home Ill post some new pics. It's getting really stocky and wild right now Can't even see the stem withou pushing away multiple leaves

Luminous efficacy/efficiency isn't the same as overal efficiency. Lumens are for our eyes, which are most sensitive to green. If an 1W Royal Blue LED puts out 550mw of 460nm light, it's still 55% efficient. Even if it doesn't put out 375 lumens. Plants don't have eyes, lumens are purely for...

It's 21 8.5W and 3 13.5W bulbs.

Because he's using Epistar/Epiled COBs and/or much higher wattage in general

With the bulb/diffuser removed, great. Higher wattage bulbs tend to be more efficient.

http://www.digikey.com/product-detail/en/osram-opto-semiconductors-inc/GW-JDSTS2.EM-HRHT-XX55-1/475-3181-1-ND/6182064 205 lm/w according to Digikey. I think the 185 lm/w comes from the Duris beinged driven higher (relative to the LM561C) on the Osram datasheet. Also according to Digikey Osram...

This is what Cree has to say about their calculator: "This PCT is offered for informational purposes only to assist with selecting LED models for lighting systems and is not a warranty or a specification. For LED product specifications, please see the data sheets available at...

To just disregard internal reflections is stupid and you are clearly lacking some understanding. If a sphere measurement concludes that a led is 55% efficient then the other 45% must ultimately be heat energy. If your condom gets heated more than what a sphere measurement would make you assume...

Yea

Osram has a contender that can match the LM561C. It's slightly cheaper per LED but has worse thermal resistance.