Whoa, i’m not dissing you, i’m dissing people who blame their problems on their lights (or dis other people's choice of lights). Competent growers use their brain (like you obviously do), not “the blame”.I have 3 lights that i adjust. I used my brain for a different effective solution. Merely stating having 3 lights in a 4 x 4 is nicer than upside down buckets.
I also run an autopot system so the height of the plant is not negotiable.
You are an ass!
You’re another one! Wasted dna.
https://cdn7.bigcommerce.com/s-f61b0/images/stencil/500x659/products/805/2714/PPFD_75W_SINGLE_COB__74869.1515705417.jpg?c=2No they don't. Don't you get tired of making stuff up?
I know you are just trolling, but let me explain for people who are actually interested in facts. The bigger the light source, the bigger the "hot spot". That's "hot spot" in the sense of a slightly brighter area and not a real hot spot where the light is really too bright, because if you get an actual hot spot then your light is simply too low.
So then for instance a 1000W HPS will have a huge center region that's more brightly lit. A 315 CMH brighter center region will be smaller, but still quite large. A 100W board or 100W COB have a similar uniformity and therefore similar sized brighter area in the center.
Now COBs are usually powered much lower than that and a 50W COB (like a Cree CXB3590) has better uniformity than a 100W board or COB and COBs at 25W are even better still (Citizen 1212).
So even just saying "COB" doesn't mean much when you can run them from 200W to say 10W.
If you have an actual hot spot with COBs (or any type of light for that matter), then you are way to close. Which would mean less than 2/3 of the distance between the rows of COBs. Anmd even then it's not bad or anything. Just a bit brighter in the center. I have my COBs a few cm/inch away from the highest tops and they are even fine with that.
Still you go for optimal uniformity and that means darkest areas still have at least 80% of the average light intensity.
Relative uniformity map for 1 COB @ 45cm (18") in a 2'x2':
View attachment 4203232
Same for a QB:
View attachment 4203233
The uniformity for the QB is ever so marginally better. Either way it's clearly preposterous to claim that a COB has a "massive hot spot".
Now where the real difference comes when you run the COBs at a lower wattage. For instance 4 COBs in the same space can be lowered to 20cm (8") instead of 45cm (18"):
View attachment 4203234
Same uniformity as with the single COB and single QB before, but you lose much less light on the walls. About 47% more light on the plants from the same watts and PPF due to lower wall losses.
Also for a small tent this lower height is much more convenient since small tents will be lower too. Less need to scrog if you gain 25cm (12") in unused height from being able to lower the fixture. With led strips you could go even lower. With 4 led strips in the same space you could go down to 3" to 4" for the same uniformity.
Now try the same with a QB @20cm:
View attachment 4203235
You get one "massive hot spot" directly beneath the board and therefore it's completely unusable at that height. So with a single QB you are stuck at that 18" and wasting a lot of light on the walls.
If you think I'm exaggerating, take a look at ledgarners measurements of the QB288 v1 vs v2. His numbers are even worse for the QB's. Probably because his tent walls are less reflective (I wonder if he uses a tent at all frankly). He gets only a peak value of 730umol/s/m2 in the center below the QB. From a light which according to the specs should give you an average of close to 1000umol over that 2'x2' at 140W. Instead the actual average is something like 550 to 600umol/s/m2 on the plants.
Understand the point you’re trying to make, but 800-900 ppfd is what you want during flowering, but across every inch of your growspace footprint, which is what great qb fixtures do, ala dan’s!https://cdn7.bigcommerce.com/s-f61b0/images/stencil/500x659/products/805/2714/PPFD_75W_SINGLE_COB__74869.1515705417.jpg?c=2
Single COB output @ 75w in a 2x2 area, massive hotspot. Put two of those together you got two massive hotspots. The more you spread the light the less hotspots. It's why a lot of LED grow lights are made from lots of low power diodes.
Are you kidding me?https://cdn7.bigcommerce.com/s-f61b0/images/stencil/500x659/products/805/2714/PPFD_75W_SINGLE_COB__74869.1515705417.jpg?c=2
Single COB output @ 75w in a 2x2 area, massive hotspot. Put two of those together you got two massive hotspots. The more you spread the light the less hotspots. It's why a lot of LED grow lights are made from lots of low power diodes.
I get sick of this crap. Same bs that light companies do, if they do anything at all.Are you kidding me?
- That chart is for a COB with a 90 degree reflector!!!!!!! With a 90 degree reflector the COB would need to be at 31" to get a proper uniformity not 18" as with a bare COB, let alone 12".
- Even with a bare COB, 12" would be too close for a single COB. Or board for that matter. So that's the incorrect height anyway and of course you will get poor uniformity.
- How do you even get an elliptical spread with a single COB?
Still, here goes, a chart for a single (bare COB) at 12" over a 2'x2' (no reflection):
View attachment 4203641 View attachment 4203644
Lines are at 20% ranges. So center white is from 100% to 80% etc. I used no reflection this time for a worst case scenario.
and same for a single board:
View attachment 4203645 View attachment 4203646
It's slightly stretched, but the board is just as unusable at that height.
The only thing you wrote that makes any sense is this: "The more you spread the light the less hotspots". That's exactly why 4 COBs spread out at 12" from each other are so much better than one COB or one board in the middle of the same area:
View attachment 4203647 View attachment 4203648
Even with no reflective walls that would be a usable configuration.
What the fuck are you on to douchebag? I posted my ppfd’s.But .. but ... but, you said you don't care about the light. The best best grower evar can grow with any light right?
Yes, for presentation purposes they have been divided by 1000! You are such a frickin dumbass!It is PPFD. Or otherwise multiply by a 1000 ...
While you keep attacking this (ie Dan) with unfounded statements like this:We feel that our COB based fixtures provide the grower with both the proper amount of PPFD as well as even and symmetrical placement of the photons across the entire intended coverage area. Our COB based lights are designed to address typical issues with indoor lighting such as corner/edge coverage, canopy heat output and evenness of PPFD spread at low (12-18” above canopy or less) operating heights.
ps If you want PPFD instead of percentages then assume the white circle in those charts is 800umol/s/m2 to 1000umol/s/m2 and lower the range by 200 for every shade darker.You underspin the cob downsides, but that’s expected here, i guess.
oi retardo, he posteted the (simulated?) light beam of ONE board, your numbers are from a combined amount of 8 boards. yet, your boards are still bound to the same beam angle of one little lm561c:Yes, for presentation purposes they have been divided by 1000! You are such a frickin dumbass!
Post your nums, so someone can replicate or call you on it.
I stated mine and where the details could be found.
Quit digging yourself a deeper hole.
And we have a winner.
The thing is when you make a suggestion, or in this case I simply gave some examples in agreement to the statement of the topic starter that COBs offer better solutions, you receive a deluge of insults from certain people who feel insecure about their board purchase.Why not make this new thing called a suggestion instead?
What's with the hysterical swearing?
I simply showed that with COBs you can indeed do the following better than with boards:
While you keep attacking this (ie Dan) with unfounded statements like this:
ps If you want PPFD instead of percentages then assume the white circle in those charts is 800umol/s/m2 to 1000umol/s/m2 and lower the range by 200 for every shade darker.
Oi douchebag, i don’t.oi retardo, he posteted the (simulated?) light beam of ONE board, your numbers are from a combined amount of 8 boards. yet, your boards are still bound to the same beam angle of one little lm561c:
View attachment 4203720
now, what do you see in this diagram? and why are you thinking this is somehow different to a typical cob?