Yikes...not sure if I have buyers remorse

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OGChops

Member
I have a 3x3 tent with a really crappy Vivosun 600w all-in-one led. Been reading a lot of posts so I decided to go DIY.

Bought from Cob Kits:
9 Luminus CXM 22 gen 3 3500K 90 CRI COBS
9 pin heatsinks, reflectors, 3 pots, thermal interface material, BJB holders

Bought from RapidLED:
3 HLG 320-C1750B Drivers

Plan is to do 3 rows of 3 COBS and make each row dimmable separately so I could dim down the center row. I will keep the wattage low enough for the 3x3 tent and hopefully have enough when I go 4x4 or 5x5. Any thoughts on this plan?
 
Airwalker16

Airwalker16

Well-Known Member
OGChops said:
I have a 3x3 tent with a really crappy Vivosun 600w all-in-one led. Been reading a lot of posts so I decided to go DIY.

Bought from Cob Kits:
9 Luminus CXM 22 gen 3 3500K 90 CRI COBS
9 pin heatsinks, reflectors, 3 pots, thermal interface material, BJB holders

Bought from RapidLED:
3 HLG 320-C1750B Drivers

Plan is to do 3 rows of 3 COBS and make each row dimmable separately so I could dim down the center row. I will keep the wattage low enough for the 3x3 tent and hopefully have enough when I go 4x4 or 5x5. Any thoughts on this plan?
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You're gonna need to spread the cobs out further apart when you do go to a 5X5. But if you wanna have an easy transition to a 4X4, I would make these fixtures of 3 cobs, BARELY fit in the 3X,3. So 33 or 36" long, however wide the tent is. Pin sinks on either end with the third in the center. Man, One single one of those 3 cobs at 320W would BLOW a 3X3 away. You're gonna need to do some Serious dimming Of your 960Watts my guy.
 
Airwalker16

Airwalker16

Well-Known Member
Damn good thing you got the "B" version drivers cause you're gonna need to dim all 3 to about 30%.
Those cobs will be running lower wattage though so you'll have some decent lumen per watt #s I'd think. This is gonna be one VERY evenly spread COB build. Will be nice to see some pics if you can when you're done.
 
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OGChops

Member
To be honest I sorta got caught up in the design. I couldn't figure out which I wanted CC or CV. Kept reading that CC was the way to go if I wanted 3 separate dimmable drivers with wired COBs in series. It scares me when I see peeps running 500v of COB in series. Am I right in thinking that dimming the center row below the outside rows with give me more even coverage? Also, figured overbuilding it now so I'm not adding later. Without a PAR meter I was just going to do the math with my multimeter to figure out my wattage output. I will build 3 pot housings and label them accordingly. I do want to make sure I'm getting a total of 400w and 200w respectively like Corey said.
Hey AW16- I'm planning to grid the floor and plumb bob the lights so each will be centered in the 9sqft. Aluminum is cheap so I will build a larger frame when I move up to 4x4. Maybe I should do a step-by-step Build Journal? Thinking about brazing the aluminum and powder coating it when built.
 
Rocket Soul

Rocket Soul

Well-Known Member
You can dim using cv or cc drivers, not only cc.

Also, whats your heatsinks rated wattage? You need fairly beastly heatsink to run your cobs at almost 100w.
 
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OGChops

Member
Rocket Soul said:
You can dim using cv or cc drivers, not only cc.

Also, whats your heatsinks rated wattage? You need fairly beastly heatsink to run your cobs at almost 100w.
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Yes duh. misspoke. Cobby recommended these:Screen Shot 2020-02-19 at 2.01.32 PM.png

Isn't my overall goal to have 9 COBS that I can run @ 50-75w max when I go bigger? Efficacy and Efficiency was why I went with the CXM 22 gen 3. Any issue with those heatsinks and my plan? I can build in some active fan airflow if this looks like an issue.
 
Rocket Soul

Rocket Soul

Well-Known Member
It should be fine upto 75w but youd be taking the cobs to 90ish at max current of those drivers. But you would never need that much in a 3x3 or 4x4. If you get a 5x5 make sure you have fans on them and calculate around 16-24" for hanging height.
Also a point in getting separate timers for the drivers, 3x inrush current could flip your fuses.
But other than that you should be good to go :)

Edit: also generally avoid reflectors if you have a reflective twnt, especially on high wattage, those puppies tend to melt. Ive seen people.light cigarettes on 100w cobs.
 
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OGChops

Member
Rocket Soul said:
It should be fine upto 75w but youd be taking the cobs to 90ish at max current of those drivers. But you would never need that much in a 3x3 or 4x4. If you get a 5x5 make sure you have fans on them and calculate around 16-24" for hanging height.
Also a point in getting separate timers for the drivers, 3x inrush current could flip your fuses.
But other than that you should be good to go :)

Edit: also generally avoid reflectors if you have a reflective twnt, especially on high wattage, those puppies tend to melt. Ive seen people.light cigarettes on 100w cobs.
Click to expand...
Yeah good point about inrush amperage. Maybe a dedicated 20A circuit. I need to do some research and I will pass it along as I figure it out but it would be nice to tie all AC power together and put a 15A IEC c14 surface mounted. Then a 12' 110v 15A c13 to NEMA for power. Let's say the lights are set at 30% for the 3x3 and I'm @ 3-400w total. I wonder what the inrush would be to strike the COBS. Those drivers pull 3.5A each I think.

Shit: No reflectors! There goes my "Patriot" design of red, white and blue
 
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