I can work with that. And there’s 4 of them right?
Is the heatsink all one piece or multiple pieces? What is size or sizes roughly? And one kind of coverage do the fans provide? I’m asking because if they’re not great, we could potentially replace with more or better fans if need be. May not need it, but now would be the time to do so.
heatsink is 13.5x4.5 inches, only one, there are fours drivers and i would say the fans are 2 inches from both ends of the heatsink. the case itself is 17.5 by 10.5. two 12V 0.25A fans. heathsink is pretty much centered
Ok. Lemme do some number crunching and get back to you.
Thanks alot!!!
I’m guessing the fans are just wired in series with two of the led strings?
Making it real easy, the 69 volt vero 29 could do that, and wouldn’t be a problem with the others that don’t have the fan inline either. That would give you 4 cobs at about 45 watts each. Ideal for 2x2. My concern with that big of a cob on a heatsink that small, is that you may want a fan directly over all 4 of them. Stay with me here on this, but if you wanted to go to 4 fans, then the voltage works out that you could move to the 50 volt cobs with one cob and 1 fan per driver. The overall power would be a little lower, but you can get into some cheaper cobs that way st same performance too.
Any of the 36 volt cobs you can fit 2 of each per driver. Limited to the low drive current, I would say doesn’t make sense to put the biggest 36 volt cobs you can get on there. A cxb is more efficient, but do you really wanna buy 6-8 of them at $40 each? I wouldn’t, you can get vero 18 and citi 1212 in high cri for under $10. Running 8 36v cobs going to be about the same amount of power as 4 of the 68-69v cobs. Depending on prices we find, the 8-36v cobs probably gonna come in cheaper than 4 of the higher voltage.
So that’s bigger decision. If you’re using the other lights, figure 3500k 90cri will give a little extra representation of the blues. But anything close to that will work.
That’s not exactly what I was picturing. Is the heatsink attached directly to the pcb or is there a plate in between them?
I looked at it from aspect of electrically working and over looked the mechanicals. We may need to back up a bit.
I can unscrew the heatsink from the plate.
My concern then is going to be how do we fit all the cobs on heatsink, and how do we hold heatsink in the fixture. Any idea?
Thats what inspired me after seeing a conversation about these on another forum. I think his setup is cool but I have one more driver to play with.
Mars 300 converted for ideas.
and this is a mars 700w. I am quoting wjhat poster said.
I just did a Mars 700 with the guidance of BigSm0. The 700 has 5 drivers but I only used 4 with one 1812 per driver. Real easy conversion, the hardest part was stripping off the old led's and sanding the surface clean.
so stripping leds and sanding could be an option…
I was thinking maybe two 72V on the drivers with fans, and then two 36V on the two other drivers?
something like this?
red dot being 72V chips.
I will open my mars 700W and see what drivers are in there, maybe we can do something else? 
Mars 700w has an extra driver and extra heatsink. DC 55-86v but slighty higher amps @ 0.715-0.73
Edit, drivers with fans on them are 0.715-0.73A, 3 others are 0.73-0.745A. there are also two switches witch could be cool maybe? possibility to “dim” by turning two drivers off or something.
You guys are freaking me out. Every post is like I want to look but I look away lol
I will end up doing something like this after another grow or two but I have this impulse control thing going on regarding anything grow related. Obsession followed by impulse buy!!! Look away screwauger, look away!!
I like playing with things… learning new things… searching the whole internet for answers … helps the anxiety you know haha but damn it always ends up costing tons of munies! lol!
Ya there’s a lot of options, I just really don’t want to overload capabilities of that heatsink on you.
Hopefully you sense the sarcasm and the fact that really, I enjoy these topics and always enjoy @dbrn32 expertise in building, improving or purchasing cost effective lighting. I am trying to wait my turn but I get what you mean about the learning and researching etc.
I often say, can you imagine the lists of things you would have to go to the library to research if the interwebs were not here. Life is good!!!
Carry on Gents.
Of course I did haha! last night i told myself I should look away but where am I now? lmfao I really wanna get this done 
should be fun.
Ive read on that other forum that the heatsink can take some good heat. its not as cheap as it looks I think lol
Do you have a way of keeping the sink in the frame?
