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exactly for a 4x4 the most common rig is 9 cobs at 60-75W each ~$550

thats the one glaring flaw with the ELG imo

typical experience here is that their yield is at or below what an HPS can do. historically most were in the 1.0-1.3 umol/J range though there might be some better ones here and there. unless youre going to buy one and throw down for photometric testing (something the manufacturer should be...

so you walk away, right? ...ppfd is also a useless number btw

yes but again spot ppfd is irrelevant. all these cheap mfrs just concentrate their diodes into a beam to get a number. coverage on that fixture is awful its not even evenly illuminating a 2x2

no and no, though with cobs the emitters are more concentrated so thermal management is more of a consideration

find an LED with an actual PPF output number (not PPFD!) otherwise you cant compare, at all

rereading i see you are 170-300 TOTAL watts, not per chip 85W per chip passive is possible.. a fan wouldnt hurt for a 2x2 you literally only need 150W so if you havent bought your heatsinks already the passives i have at my site can handle 75W without a fan, or they also can mount a small 50mm...

welcome mr. tomato! they are very efficient but not the most cost effective. the 38mm package is somewhat common but not as common as a 28mm package id have to look at the numbers but off the top of my head 4 cxm22 should outperform 2 cxm32 at the same chip/holder cost and offer better...

sure, email me at [email protected] a 4-cob/200W fixture would be just over $200 you just need to build a simple frame

hard to say as neither of the lights you mention actually tell you how much light they put out. the 418W your vipar is using should be more than enough for that tent a decent effcient (i would consider neither of those to be decent) LED light would use 200-250W in your space id replace the...

you'll get about 340W out of 4 cobs on that driver add a 5th cob/heatsink/holder and you'll be ~400W and that would compare to a 600HPS would be a lot of light for a 3x3

4 cobs at 75W each on 133mm heatsinks with hlg-320, about $295 shipped

If youre serious about LED save up a little a 4x4 requires about 500W and the drivers alone will be over $150, before you get into the actual LEDs if your budget is that limited id buy an HID before the two lights you mentioned you can prob find a 600W HPS on craiglist for $200 and throw a...

::takes notes:: ;)

i havent researched your specific example but heres a general one chip = 2.0 umol/J at 25C correct to Tj at 70C (realistic if not conservative for 200W thru a chip) = 0.95 typical lens or reflector = 0.93 typical driver = 0.91-0.93 these losses are cumulative so theres 80% net efficiency...

i would just go snag the proper mag ballast, people practically give them away on craigslist

good call. build the actual fixture with drivers and optics and put it in a sphere at steady state operating temperature and then you will see that the system level efficiency is about 70-80% as efficient as the chips tested alone at 25C

$550 for a 725W rig of 9 luminus on 3 hlg-185h-48a drivers. its not under $500 but will save you $200 a year in electricity and $50-$100 a year in bulbs over a 1000W HPS

posting realistic assessments about the lights you are asking about is not "hating" if they are in fact substandard, don't take it personally. You seem to be always on the hunt for deals that are too-good-to-be true, so dont be shocked when they are in fact, demonstrated to be too good to be...