One COB light for veg and flower

I have a small grow area about 18" x 27" x 48" high. I want to create a COB light I can use for both veg and flower. From reading I'm thinking of 6 VERO 18, 4000K on dimmable driver. Run at lower power for veg and crank it up for flower.
Or 6 Vero 18, 3500K for flower, 4 Vero 18, 5000K for veg, dimmable driver on an SPDT switch all mounted on the same HS/Fan.
I'm thinking 2 plants at a time. Veg under 4 cobs centered over them then flower on the 6 with a wider light spread.
Or maybe 3 Vero 29s on a dimmer. I have a hard time thinking about this not knowing the lights footprint coverage at heights that I have.

Suggestions??

youre in the ballpark, most people like 3500 and 4000

just remember that not only is a cree 4000 not the same as a vero 4000, but each of those also have different CRI models

FWIW, I went with CXB3590 3500K CD BIN for veg and bloom. They're said to better at blooming than veg. If that's the case I'm prepared to be amazed because the things are already making my veg grow like nothing else, ever.

So there's no need for 2 different COBs to veg and bloom. Good. I thought that was the consensus. So the real question becomes which COBs to use for my 18"x27" x48H space. 2 CXB3590's dimmable or 6 Vero 18s or Cree equiv. dimmable. Will the Crees be too hot at the end and burn the bud?? That would be bad.

With 48" of height the crees will be fine on a dimmable driver. I'm running two cxa3070 in a 20"x11"x29" and it's working out great. I use the 3000k and they work great for veg and flower. The ability to dim is the most important aspect imo.

With the Vero cobs 4000K seems to be the most favoured for veg/bloom.
With Cree it's 3500K.

Lower also works.

They both have plenty of blue for veg and more than enough red for bloom.

frica said:

With the Vero cobs 4000K seems to be the most favoured for veg/bloom.
With Cree it's 3500K.

Lower also works.

They both have plenty of blue for veg and more than enough red for bloom.

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Indeed I deliberately chose my concept of an ideal spectrum, I'm just applying it everywhere.

ttystikk said:

Indeed I deliberately chose my concept of an ideal spectrum, I'm just applying it everywhere.

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How did you figure out is was an ideal spectrum?

CXB 3590 3000k does well for me in veg and bloom.

p4id said:

CXB 3590 3000k does well for me in veg and bloom.

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Did you go with the high cri? Those look tempting to try out with the higher bin available now.

Are you on a budget or just looking for the best setup for your space? I have been a fan of the 3000k and 2700k cobs ever since @bbspills showed some fat nugs grown under cxa3050 2700k. Better chips and bins have come out since and there isn't a lot of interest in them.

I think two vero 29 2700k or cxb-3590 90cri 3000k would give plenty of light for a single plant each in the small area you have. Supplementing those with some smaller chips like the single die cree XM-L2 or the vero 13s in higher color temps would give you some great control over total spectrum. If they start stretching you could turn up the blues until they quit. Smaller chips could also be used to light up the perimeter where the big ones dont reach.

This is just an example and I may be overthinking it a little but it's the way I may be heading with my future projects. Running different dimmable drivers for each spectrum to have something to fiddle with. Single spectrum works great too and is much simpler to do.

ttystikk said:

FWIW, I went with CXB3590 3500K CD BIN for veg and bloom. They're said to better at blooming than veg. If that's the case I'm prepared to be amazed because the things are already making my veg grow like nothing else, ever.

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lol you led freaks always say shit like that. well see how smart you look in winter when youre house is freezing and im walking around in my underwear because my whole house is 89 degrees from my gavitas....

Im going to make a couple strips using 4 3000k 36v 2530s adding 2 5700k 9v 1304s to boost blue spectrum a bit and eat up some excess voltage. They will all be running @ 700mA so the 25's will be running very efficiently and the 13's will be about 300mA under max...

I'm using vero 29 3000k for veg and bloom, they work well.

BOBBY_G said:

lol you led freaks always say shit like that. well see how smart you look in winter when youre house is freezing and im walking around in my underwear because my whole house is 89 degrees from my gavitas....

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Believe me when I tell you that my home is and will continue to be well warmed by my grow. You would be impressed, and I mean that most highly.

Brettsog:
How big is your grow area??

thetr33man said:

Im going to make a couple strips using 4 3000k 36v 2530s adding 2 5700k 9v 1304s to boost blue spectrum a bit and eat up some excess voltage. They will all be running @ 700mA so the 25's will be running very efficiently and the 13's will be about 300mA under max...

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I like this idea as well. How do you determine how many COBs to use in a given space?? I feel like I'm missing a major piece of this puzzle and I've been reading this forum for months. Thanks for your help. What do you guys recommend for small area like mine- 18" x 27" ?? I am really wanting to get building. But the configuration is just not clear.

Thanks

ttystikk said:

Believe me when I tell you that my home is and will continue to be well warmed by my grow. You would be impressed, and I mean that most highly.

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no way your leds can put out like my gavita, its the heat yo.

60+% efficient as a heater

Jack Reacher said:

I like this idea as well. How do you determine how many COBs to use in a given space?? I feel like I'm missing a major piece of this puzzle and I've been reading this forum for months. Thanks for your help. What do you guys recommend for small area like mine- 18" x 27" ?? I am really wanting to get building. But the configuration is just not clear.

Thanks

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short answer is not only are there all kinds of cobs at different output but for a given cob there is a large range of output depending on how hard you run it.

rule of thumb is 15-20 PAR watts/sf so how many 'real' watts you need is a function of your efficiency, which is a function of # of cobs and how hard they are driven.

so you have about 3 square feet so you need say 60 par W

this can be accomplished by:
(1) 150W cob at 40% efficient = 60 par W
(4) cobs run at 25W that are 60% efficient = 60 par W

the first creates 90 W of heat
the second creates 40W of heat but costs $150 more initially, that you will eventually make up down the road.

smaller setups like yours are often run on the less efficient sidewith little consequence

BOBBY_G said:

short answer is not only are there all kinds of cobs at different output but for a given cob there is a large range of output depending on how hard you run it.

rule of thumb is 15-20 PAR watts/sf so how many 'real' watts you need is a function of your efficiency, which is a function of # of cobs and how hard they are driven.

so you have about 3 square feet so you need say 60 par W

this can be accomplished by:
(1) 150W cob at 40% efficient = 60 par W
(4) cobs run at 25W that are 60% efficient = 60 par W

the first creates 90 W of heat
the second creates 40W of heat but costs $150 more initially, that you will eventually make up down the road.

smaller setups like yours are often run on the less efficient sidewith little consequence

Click to expand...

Thanks, I'm getting somewhere. I think I like the 4 cobs at 25w. Wider light coverage, less heat. Are 2 plants 2 many for my space?? I need to know. ??