Any information on most optimal cob placements/layouts?

HandyGringo · Sep 21, 2016

I've been looking at building a cob LED with 4 or 5 cobs. For 2x2, and there's not a lot of resources out there except anecdotal evidence and very few personal reviews etc. Is there any concensus on the ideal layout for 4 or 5 cobs?

I found a build by Growmau5 which featured 5 cobs, but it created a bit of a hotspot in the middle because of the 5'th cob..

It was like this:

x-----x
---x---
x-----x

What if I'm going to use 4 cobs? That would probably have the opposite effect.. Like, too little power in the middle.

Wish there was like an emulator for this. Where you could input the area, the height, and then play around with x amount of cobs at x power, and see how the estimated par readings would go.

Airwalker16 · Sep 21, 2016

HandyGringo said:
I've been looking at building a cob LED with 4 or 5 cobs. For 2x2, and there's not a lot of resources out there except anecdotal evidence and very few personal reviews etc. Is there any concensus on the ideal layout for 4 or 5 cobs?

I found a build by Growmau5 which featured 5 cobs, but it created a bit of a hotspot in the middle because of the 5'th cob..

It was like this:

x-----x
---x---
x-----x

What if I'm going to use 4 cobs? That would probably have the opposite effect.. Like, too little power in the middle.

Wish there was like an emulator for this. Where you could input the area, the height, and then play around with x amount of cobs at x power, and see how the estimated par readings would go.

4 cobs is great for uniformity. But if you do use 5, just do a pentagonal shape and it'll be perfect .

HandyGringo · Sep 21, 2016

Airwalker16 said:
4 cobs is great for uniformity. But if you do use 5, just do a pentagonal shape and it'll be perfect .

Won't there be a... Coldspot? In the middle if you do 4? I want to use it for a 2x2.. So for it to cover it all the cobs would probably be 1 feet apart, would that work?

Danielson999 · Sep 21, 2016

If you're running at a low amperage then there won't really be a hot spot anyway, even if you're less than a foot away from the plants. Even if you used 9 cobs to perfectly fill a 2x2 space there will still be a warmer spot. 4 cobs or 5 cobs will work great. It would be funny to see someone use a separate driver on the middle cob of a 5 cob setup and dim it down a bit to remove the 'hot' spot.

HalfBee · Sep 21, 2016

You are looking at buying a kit... (guess based on the 4 or 5 cob configuration)
But what if you could run 6 cobs in that space? 3 bars of 3 giving 4 overlap "warmer' zones.

2x2 isn't a lot of space to work with, but it's what I plan for my cabinet - start with 3 & add second bar when budget allows.
Running at 1000mA I can rock 6 CREE or Vero all night long. Cutter's got what you want, just not all in a neat GrowMau5 kit.

Buck 'em if they can't take a toke...

HalfBee

HandyGringo · Sep 21, 2016

HalfBee said:
You are looking at buying a kit... (guess based on the 4 or 5 cob configuration)
But what if you could run 6 cobs in that space? 3 bars of 3 giving 4 overlap "warmer' zones.

2x2 isn't a lot of space to work with, but it's what I plan for my cabinet - start with 3 & add second bar when budget allows.
Running at 1000mA I can rock 6 CREE or Vero all night long. Cutter's got what you want, just not all in a neat GrowMau5 kit.

Buck 'em if they can't take a toke...

HalfBee

I was planning on building it myself, no kit. Since I'm in Europe I can't use those kits, or cutter :/ But thanks for the tip.

And 6 cobs sound expensive as fuck. :/

But it's a nice idea, I'll consider it. But 6 cobs sound like an awful lot for 2x2 though.

Danielson999 said:
If you're running at a low amperage then there won't really be a hot spot anyway, even if you're less than a foot away from the plants. Even if you used 9 cobs to perfectly fill a 2x2 space there will still be a warmer spot. 4 cobs or 5 cobs will work great. It would be funny to see someone use a separate driver on the middle cob of a 5 cob setup and dim it down a bit to remove the 'hot' spot.

I think I might be using the wrong word. I don't mean a hotspot like it burns the plant, but a spot where the light is a lot more powerful, and not even over the whole area covered.

Like ideally the corner of the tent would be the same par reading as the middle

HalfBee · Sep 21, 2016

Yep... 6 would be a lot for a 2x2 --- If running the most powerful cobs at their meanest drive currents...
But consider the 3070 or Vero 18 at 1000mA, not quite as intense, less heat, lower cost.
I'll settle for what get's the job done and plan the good stuff for the NEXT larger project in dream mode...

This is cobCalc for 6 V18 compared to 4 of the higher costing cobs V29, 3070, 3590 for same area
800 PPFD I think is good enough, yeah not as efficient but $30 to $130 savings in up front cob expense

That 35 inch heatsink... cut in half and that's your 18 inch bars inside.
Check my thread on the Buck drivers... One cob or max there's more options for DIY small spaces.

Whatever you decide l hope you post some progress.

Airwalker16 · Sep 21, 2016

No man just bring the cobs 6" in from each of the corner walls and youll be good.

HandyGringo · Sep 21, 2016

HalfBee said:
Yep... 6 would be a lot for a 2x2 --- If running the most powerful cobs at their meanest drive currents...
But consider the 3070 or Vero 18 at 1000mA, not quite as intense, less heat, lower cost.
I'll settle for what get's the job done and plan the good stuff for the NEXT larger project in dream mode...

View attachment 3786356

This is cobCalc for 6 V18 compared to 4 of the higher costing cobs V29, 3070, 3590 for same area
800 PPFD I think is good enough, yeah not as efficient but $30 to $130 savings in up front cob expense

That 35 inch heatsink... cut in half and that's your 18 inch bars inside.
Check my thread on the Buck drivers... One cob or max there's more options for DIY small spaces.

Whatever you decide l hope you post some progress.

I really appreciate this comment, and going to give it a look tomorrow, I'm super fucking stoned and the numbers are hard to get to make sense. Thanks a lot for the help though!

Airwalker16 said:
No man just bring the cobs 6" in from each of the corner walls and youll be good.

6 inches from the corner of the tent or corner of the cob fixture?

Airwalker16 · Sep 21, 2016

HandyGringo said:
I really appreciate this comment, and going to give it a look tomorrow, I'm super fucking stoned and the numbers are hard to get to make sense. Thanks a lot for the help though!

6 inches from the corner of the tent or corner of the cob fixture?

Make sure the cob is 6" from both walls. Not diagonally from the corner. Just make the frame hold the heatsinks so it's got the cob centered on the point.

HandyGringo · Sep 21, 2016

Airwalker16 said:
Make sure the cob is 6" from both walls. Not diagonally from the corner. Just make the frame hold the heatsinks so it's got the cob centered on the point.

Is 6 inches the minimum? So the heatsink needs to be at least 12.5 inches wide and long? What about those round heatsinks I've seen, those seem to do fine, yet only have around 1 inch around them. If that makes sense

testiclees · Sep 21, 2016

Danielson999 said:
If you're running at a low amperage then there won't really be a hot spot anyway, even if you're less than a foot away from the plants. Even if you used 9 cobs to perfectly fill a 2x2 space there will still be a warmer spot. 4 cobs or 5 cobs will work great. It would be funny to see someone use a separate driver on the middle cob of a 5 cob setup and dim it down a bit to remove the 'hot' spot.

My setup uses different drivers & cobs but opposite design. Ive got 4 v29@80w each as center of a 48 x 12" fixture. On each end 2-3590@50w each. It requires a lot of clearance.

Rocket Soul · Sep 22, 2016

HandyGringo said:
I've been looking at building a cob LED with 4 or 5 cobs. For 2x2, and there's not a lot of resources out there except anecdotal evidence and very few personal reviews etc. Is there any concensus on the ideal layout for 4 or 5 cobs?

I found a build by Growmau5 which featured 5 cobs, but it created a bit of a hotspot in the middle because of the 5'th cob..

It was like this:

x-----x
---x---
x-----x

What if I'm going to use 4 cobs? That would probably have the opposite effect.. Like, too little power in the middle.

Wish there was like an emulator for this. Where you could input the area, the height, and then play around with x amount of cobs at x power, and see how the estimated par readings would go.

One way of going in order to avoid the hotspot in the middle is by using a lower voltage cob in the middle,in series with the other cobs on the same current it will give u less watts in the middle. Should be possible to do with 4 50v cobs and a 36v in the middle on a meanwell hlg 240 c1050.
But if u look at the growmau5 vid: he is trying to cover a 3x3 (or 1m2) and gets not enough coverage for the edges. Hence quoted hotspot. But infact he has very good coverage for a 2x2.
But it seems like most people like 1 cob/ft2 so 4 should be good aswell as long as u go for +15 par watts/ft2

sixstring2112 · Sep 22, 2016

good layout for a 3 x 3'super simple ,thanks mau mau :hump:

he shows a hotspot in the center that would not exist with only 4 cobs,prolly close to perfect

morgwar · Mar 3, 2017

HalfBee said:
Yep... 6 would be a lot for a 2x2 --- If running the most powerful cobs at their meanest drive currents...
But consider the 3070 or Vero 18 at 1000mA, not quite as intense, less heat, lower cost.
I'll settle for what get's the job done and plan the good stuff for the NEXT larger project in dream mode...

View attachment 3786356

This is cobCalc for 6 V18 compared to 4 of the higher costing cobs V29, 3070, 3590 for same area
800 PPFD I think is good enough, yeah not as efficient but $30 to $130 savings in up front cob expense

That 35 inch heatsink... cut in half and that's your 18 inch bars inside.
Check my thread on the Buck drivers... One cob or max there's more options for DIY small spaces.

Whatever you decide l hope you post some progress.

This is old but thanks for this post I really needed this info. I just put 6 vero 18's in an anjeet "1200" using the cheap chinese drivers and heatsinks. Supposedly rated at 30-50vlts 1200+5%ma I'm thinking your calc numbers are dead on not bad for 160 bucks total. Oh and run really cool temps.

HalfBee · Mar 3, 2017

Yep, the numbers looked even better with the 1212 at same price point as the Vero 18 (another day another build)
Since I'm at 30 watt x 6 I've let the last round grow within 8 inches of the fixture with no bleaching/heat problems.
Still experimenting with placement height but plants are happy at any level so far.

morgwar · Mar 3, 2017

HalfBee said:
Yep, the numbers looked even better with the 1212 at same price point as the Vero 18 (another day another build)
Since I'm at 30 watt x 6 I've let the last round grow within 8 inches of the fixture with no bleaching/heat problems.
Still experimenting with placement height but plants are happy at any level so far.

No doubt I'm buying another one and doing the 1212s just to have it.
I do plan to jump to a bigger cabinet soon like a 4x4
My flux readings have gone up I wonder if drivers have a break in time.

Mullumbimby · Mar 3, 2017

HalfBee said:
Yep... 6 would be a lot for a 2x2 --- If running the most powerful cobs at their meanest drive currents...
But consider the 3070 or Vero 18 at 1000mA, not quite as intense, less heat, lower cost.
I'll settle for what get's the job done and plan the good stuff for the NEXT larger project in dream mode...

View attachment 3786356

This is cobCalc for 6 V18 compared to 4 of the higher costing cobs V29, 3070, 3590 for same area
800 PPFD I think is good enough, yeah not as efficient but $30 to $130 savings in up front cob expense

That 35 inch heatsink... cut in half and that's your 18 inch bars inside.
Check my thread on the Buck drivers... One cob or max there's more options for DIY small spaces.

Whatever you decide l hope you post some progress.

Brilliant to see the data represented like this. In my mind, for a 2x2 @HalfBee 's table makes it a No-Brainer to go 4x3590. The extra dough is almost negligible, compared to advantages in every other way - much more light, much less heat. (You wont miss the heat)
There certainly won't be a hot or a cool spot, if you follow @Airwalker16 's advice above.
Enjoy!
Edit: A 'Nominal' 200W driver will allow you to go a bit over 50W too, but 50W per sq ft will be sensational

CobKits · Mar 3, 2017

Mullumbimby said:
Brilliant to see the data represented like this. In my mind, for a 2x2 @HalfBee 's table makes it a No-Brainer to go 4x3590. The extra dough is almost negligible, compared to advantages in every other way - much more light, much less heat. (You wont miss the heat)
There certainly won't be a hot or a cool spot, if you follow @Airwalker16 's advice above.
Enjoy!
Edit: A 'Nominal' 200W driver will allow you to go a bit over 50W too, but 50W per sq ft will be sensational

do a little more research, there are at least half a dozen cobs that are better and cheaper than the 3590 by now

Any information on most optimal cob placements/layouts?

HandyGringo

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Airwalker16

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HandyGringo

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Danielson999

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HalfBee

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HandyGringo

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testiclees

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