Tyleb173rd
Well-Known Member
The DIY COB builds fascinate me and the very easy tutorials by members here have boosted my confidence in making one. But if they are so good does that make the blue/reds obsolete?
SupraSPL, where are you getting those efficiency numbers? I can only seem to find luminous flux ratings, not radiant for CXBs. Cree's XTE series royal blue is 53% efficient (http://www.cree.com/~/media/Files/Cree/LED-Components-and-Modules/XLamp/Data-and-Binning/XLampXTE.pdf) and it makes it seem very unlikely CXBs would reach an efficiency of 69%. I'm very open to being corrected (and really I want to be, since I'd considering using CXB for my next grow light) but I need to see links to support your statements.Comparing them in terms of conversion efficiency and cost/PAR W, the monos seem to be lower efficiency and cost more. The exception is the blue, but we typically only use 10-20% blue so that doesnt help mono's case much. When you consider the labor involved and the cost of lens/reflectors, the COBs are even more appealing.
Luxeon ES deep blue 450nm, N4R bin, $2.50 ea. @700mA (2W) 62.6% efficient typical - cost $2.04/PAR W
Cree XPE2 red 630nm P4 bin, $2.75 ea @700mA (1.7W) 43.7% efficient typical - cost $3.75/PAR W
Cree XPE photo red 660nm bin 14 $2.81 ea @ 700mA (1.5W) 45.4% efficient typical - cost $4.03/PAR W
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Cree CXB3590 3500K 80CRi CD bin $43 ea @1.4A (50W) 56% efficient typical - cost $1.56/PAR W
Cree CXB3590 4000K 70CRi DB bin $43 ea @1.4A (50W) 61% efficient typical - cost $1.44/PAR W
Cree CXB3590 3500K 80CRi CD bin $43 ea @.7A (23W) 64% efficient typical - cost $2.93/PAR W
Cree CXB3590 4000K 70CRi DB bin $43 ea @.7A (23W) 69% efficient typical - cost $2.64/PAR W
Try this to find out where the numbers Supra uses for the CXB efficiency come from. Some people have their doubts to their validity but regardless it's an excellent way to get a grip on how much light one needs when growing with COBs and whites in general.SupraSPL, where are you getting those efficiency numbers? I can only seem to find luminous flux ratings, not radiant for CXBs. Cree's XTE series royal blue is 53% efficient (http://www.cree.com/~/media/Files/Cree/LED-Components-and-Modules/XLamp/Data-and-Binning/XLampXTE.pdf) and it makes it seem very unlikely CXBs would reach an efficiency of 69%. I'm very open to being corrected (and really I want to be, since I'd considering using CXB for my next grow light) but I need to see links to support your statements.
I used cheap red/blue panels 3 or 4 years ago. They were only about 28 actual watts (as measured with a watt meter). I had 4 of these - they worked well for seedlings but just didn't put out enough light for anything but small plants. LED flood lights became reasonable and I decided to try a couple. They work remarkably well for vegging having excellent penetration and I've added several more. They are cheap, Chinese made (what isn't) LED flood lights and reliability is an issue. I always keep backups and I have no problem sourcing ($5 per 50 watter) and installing the COBs when they fail.The DIY COB builds fascinate me and the very easy tutorials by members here have boosted my confidence in making one. But if they are so good does that make the blue/reds obsolete?
Very interesting to think through that math. I reserve the right to be skeptical, but nevertheless I value their hard work as well as your reply. Thanks so much for taking the time to respond. I did several searches on RIU and the web but found it difficult to locate any good info.Try this to find out where the numbers Supra uses for the CXB efficiency come from. Some people have their doubts to their validity but regardless it's an excellent way to get a grip on how much light one needs when growing with COBs and whites in general.
http://rollitup.org/t/math-behind.868988/
I don't think Supra did the math for the latest Osram or Philips Reds but regardless COBs just make getting a good spectrum that much easier than monos. Matching, mixing, and measuring monos is practically a guessing game unless you're a stone cold engineering stud or have a sphere.
If Cree provides us with correct charts and numbers, Supra's calculations are very close to reality. He's using luminous flux values halfway to the next bin, though.Very interesting to think through that math. I reserve the right to be skeptical, but nevertheless I value their hard work as well as your reply. Thanks so much for taking the time to respond. I did several searches on RIU and the web but found it difficult to locate any good info.
well, crees bins are MINIMUM flux, so they would generally be expected to flux somewhere in the middle of that rangeIf Cree provides us with correct charts and numbers, Supra's calculations are very close to reality. He's using luminous flux values halfway to the next bin, though.
Speaking of new bins, there's one coming for CXB3590 chips, among others. I'm sooooooooo excited!If Cree provides us with correct charts and numbers, Supra's calculations are very close to reality. He's using luminous flux values halfway to the next bin, though.
Top bin XT-E RB is over 70% efficient at 100mA. The single dies in CXB3590 are driven at similar power levels.
SupraSPL, where are you getting those efficiency numbers? I can only seem to find luminous flux ratings, not radiant for CXBs. Cree's XTE series royal blue is 53% efficient (http://www.cree.com/~/media/Files/Cree/LED-Components-and-Modules/XLamp/Data-and-Binning/XLampXTE.pdf) and it makes it seem very unlikely CXBs would reach an efficiency of 69%. I'm very open to being corrected (and really I want to be, since I'd considering using CXB for my next grow light) but I need to see links to support your statements.
Yes, that highlights the reason COBs are reaching such high efficiency compared to single diodes, reducing current droop and to some extent temp droop.Top bin XT-E RB is over 70% efficient at 100mA. The single dies in CXB3590 are driven at similar power levels.
A great point. The studies I have looked at suggest faster growth rate for blurple (at least in the species studied), but there is much to be said for COB PPFD power, convenience, cost, and, like you said, being able to see what you love. That and my wife won't let me have a purple light without a grow tent.Take a look at the McCree curve. While it is completely true that certain parts of the spectrum lead to faster growth, it is also true that warm white does a very good job of replicating the curve. Most LED companies omit tons of the yellows and greens and your grow room looks like you're on Mars. Whatever slight decrease in optimality you may receive by not using just reds for example (where the peak of the spectrum occurs) is more than made up for by being able to actually see your flowers fairly accurately (high CRI) and appreciate them in their natural glory.
A great point. The studies I have looked at suggest faster growth rate for blurple (at least in the species studied), but there is much to be said for COB PPFD power, convenience, cost, and, like you said, being able to see what you love. That and my wife won't let me have a purple light without a grow tent.