Let's talk DIY lights


Talking about Samsung lights got me to wondering if they made COBs. Turns out they do. What’s the story with the Samsung COBs @dbrn32? Looks like they only go up to 80 watts max and don’t have as high of lm/W. Also not sure of the price (haven’t checked yet).


Interesting @Bogleg find any prices on those?

@dbrn32 how close can I run the Cree 3590’s to the plants? 12” is the measurements to the tallest. All others are 18”ish. Lights are at about 90%-100%. The pot is not turned quite all the way to max. About 1/4-1/8th turn off from that.


My understanding is that their cob technology isn’t competitive with the other major players. But if you see something we can definitely take a look at it.

Kind of makes sense. They’re just dumping more of their r&d time and funds into the mid power market. As to where Cree is behind there, but their cob and mono’s are top notch. There’s not a really a single company that blankets the entire led market in every category.


I’ve never run the cree’s above 50 watts, but had them in the 10-12” above canopy without issue there.


Nice fixture you have there :heart_eyes:


@dbrn32 Ok I’ll keep you posted if I see any bleaching. I just lowered the fixture down. I figured I was safe, but double checking.

Going to transplant munchkin today after work, I didn’t see any roots but there’s too much new growth to not think there’s no roots.


Thanks @M4ur I really love it. Very efficient, good penetration into the canopy. I want to get rid of the purple fixuters, but I paid good money for them… (time for another tent!) I’m intend to add 4 quantum panels in between the rows of cobs off from center. That calling it good after that. But I still need an identical fixture like that to cover the other 4X4 area. All in good time.


Sounds good! I’m sure it’s fine, looks too good to be any less.


@Covertgrower here’s a tip, when you turn your lights up slowly you will get to the point where you don’t see the light get brighter but you still have dial left. This is close to :100: light output and turning up farther will just create more heat/ not light. Then move your lights closer until you see the first signs of a problem and wa lla.


@Daddy they still have more lumens to put out if I turn the pot up… I purchased upgraded drivers to drive them a little bit harder. At 110% @dbrn32 was better at explaining it. But I have the basic concept.


Cool, my setup is a little different and it is what I found with mine. Grow is looking good too.


He’s capable at running at up to 1750ma instead of they typical 1400ma you generally see Cree builds at is the only real difference in your driver.

Assuming your pot is a true 100k, the light output will increase all the way up whether it appears to or not. If you exceed 100k resistance then you wherever you hit 100k will be max output and you shouldn’t see an increase in light or heat output.

But the amount of light per watt will definitely go down as the dimmer is increased. It just won’t ever hit zero. The data sheets all have that info. But i would expect something like a 3-5% drop from 1400ma-1750ma, not for the light output to just drop to nothing.


So I am hitting 100k before turned all the way is all it is then? They are 100k+ pots so maybe 110-120. I didn’t measure them before I did the install.


Probably. I can say for sure without looking at what you’re talking about in person, but I would guess that’s what you’re seeing. Should be max output current at 100k and then anything beyond that will just be deadband in the pot.


My Blue Dream plant is sitting right iunder the middle of 4 COBs. When I move the lux meter up the plant, before it gets to the top the lux level starts to go down. The plant is getting light from all 4 COBs but at the top the rays are so sideways they are weaker! Still in the 50000 lux level, but a foot lower it is getting 70000. It’s having a great effect on the lower branches which are all growing up almost level with the top. Each lower branch is more directly under a COB.


That makes sense right? Top center of your plant doesn’t have a light directly above it, so what you’re seeing is the 4 cobs blending up until you high enough that as much of the light beams aren’t touching each other as much. But when you get to the side of your plant that does have a cob directly above it, your light is more intense from the more direct beam of light?

Is that with or without the reflectors, and what is your cob spacing?


COBs have angelica reflectors from rapidled. Spacing is about 10" in one dimension, 20" in the other. Yes, the reflectors are directing the side rays down instead, so the plant top does not get as much light.

May be time to raise the lights a bit more. I have to start pruning this to be a mother plant soon. It just looks so beautiful right now!


@1BigFella interesting. I opted not to have reflectors. I wonder what my light measurements might be?


Watt for watt you’ll be lower directly under your cob, but higher as you get out to sides.


I have a lux meter. Directly under a COB on the floor it went from 6000 lux to over 13000. It actually doubled the light reflecting off my side walls too. But the very top couple feet of my grow chamber side walls got dark. No problem: I don’t grow any plants up there.

RapidLED has them for $9.50 for Vero29s (but not Vero29SE). They have another one but I don’t remember which it was.