12 low wattage cobs would kill it in a 4x4.When i was doing all this research before and estimating it all i multiplied the square footage by 35 watts and figured that was a good spot to be on cobs,15 cobs (3 rows of 5 was a cob every square foot.
Than you need to figure out how much to drive the cobs to get to your target wattage cause after all the power company charges you by the watt not by the amp.
Multiply the forward voltage of the cob by the amps on the driver.a 1400mA driver for example will give you 1.4 amps.
the D series Vero is 37.5 volts.Multiply 37.5 X 1.4 and gives you 52 watts per cobb.Multiplied by 5 is 262 per driver or 5 cobs and multiplied by 3 is 786 watts total on my 4x5 which is really perfect.
You can get a 1.7 amp driver and use less cobs and still get the wattage up but the idea here is efficiency.More cobs less wattage means more efficient.Run them on 220 and it drops the amp pull in half so the drivers run cooler.
in a 4x4 i would use 12 D series veros or the cree CXB3590s
You can use the 1400mA 320 driver and run 6 cobs on each driver.
the crees are 36 volts so 36v x 1.4 = 50.4 watts X 6 = 302 watts.The Meanwell 320H 1400 will be the perfect driver.
The veros run a little higher on voltage so you will get a little more wattage out of the vero D series cobs.
spacing is easy just do 3 rows of 4 and be done with it.
would be bright as shit and run super efficient and last 10 plus years.
Heres the 15 cob i built for the 4x5 and this shit owns with 3 240H 1400mA drivers on 240V.
I mounted my drivers in an alumimum frame and its all wired up to harneses that can unhook.The framing was easy to build and the wiring is all soldered together.Easy shit.
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