Buying the Mars 300 at $70, on the other hand, might be an attractive component of a CXB3590 DIY build.
Does anyone have the 'recipe' for converting a 300? It would be a fun project for me to build a veg light using Cree and a repurposed lighting fixture.
I am in the same boat, getting a light with 4x CXB 3590 now which means I'll have two MarsHydro 300W lights over.
I am not planning to run them in addition with the COBs - but I might extend my growing area in the future and might want additional CREE COBs, so making a "Ghetto COB" out of the MarsHydro would be a fun project!
As far as I can tell, this should be REALLY easy, I had the MH lights open many times already. Basically you would disassemble them, AFAIK there is also a way to separate the heatsink from the PCB with the LEDs.
Then you slap ONE COB on there or if you want even two - the only issue is with the size of the case so that with TWO COBs in one housing the COBs would only be about 15cm apart which I don't consider optimal, but it'll definitely work.
The two MH drivers are 60W each, DC out: 55V-100V@0.69A - 0.72A so they can only deliver 0.72A, that would be "ok" for a 72V COB under-driving (maybe there are better suitable COBs for those drivers??)..or you get some ebay drivers for $15-$20 that can deliver some more amps if you want to drive the COBs a little harder than 0.72A. (Building a light with MH 300W case and a Meanwell driver for €82 I don't see as too smart, mainly because of the small case, small heatsink etc, then rather a bigass 80cm length heatsink and proper distance of the lights.
The heatsink of the MH w/ the fan is rather underdimensioned so I wouldn't want to run them too hard, but it should be able to do two COBS at 50/60W each. I am seeing myself doing this already just out of boredom
*** Alternatively ***
I don't want to do this since I THINK the COBs will be all I need, but you can well re-purpose the MH and make them additional vegging or flowering lights.
You can get 3W (READ: 3W, because "5W" Epistar chips don't actually EXIST!!), those exact chips on ebay. I just got some from UK to replace some of my MH 300W "5W" (cough, cough) LEDs.
The LEDs used in those lights (not offical, my own findings):
14 Blue (12 Dark/Royal Blue, 2 Bright Blue)
33 Red (17 Bright Red, 16 Deep Red)
13 Warm White 3500k
Deep Red (640-660nm), Bright Red (620-630nm), Royal Blue (440-450nm), Bright Blue (460-470nm)
So when you have white COBs already, remove the whites and reds of the MH light, and then just solder to you heart's desire a bunch more Royal Blues and a few Bright Blues.
Or for a flowering lamp, remove blues and whites and add more Bright Red and Deep Red.
Check the ebay vendor "futureeden", this is where I got my LEDs from.
** Funny advice: When you solder, do NOT melt any working LEDs with your fricking soldering iron
![Smile :) :)](/styles/smilies/icon_smile.gif)
I have this stupid soldering iron with a screw sticking out, I couldn't believe it, I replaced 4 broken LEDs and while doing so melted 4 or 5 others which were totally fine by accidentally touching them with the iron...seriously....FACEPALM. Fortunately I had enough spares...
![Smile :) :)](/styles/smilies/icon_smile.gif)