there are reputable chips around that price by citizen, cree etc. they are just smaller les with less diodes. no need to buy the noname chinese junk that usually has wide flux ranges, low lumen maintenance, and unrelaible lifespan. for jsut a few more dollars. gen5 citi 1212s can be had for $8 and are a fantastic reliable chip. and yes you are right 4 of those crush a $32 cxb3590
I doubt that you(&me) are able to do exact measurements of the flux.
i can do pretty well with my integrating sphere, even in absence of calibrating it
all i need are relative measurements, and these are accurate and repeatable
i should have said "in the range we typically runs these cobs when halving
*wattage* efficacy gains are generally 8-12%.
if you go by halving *current* thats really not halving the power input as the voltage drops and the gains are magnified. You can measure that way but most people care about overall wattage as opposed to what particular current their chip is drawing to get to that wattage
heres some sphere tests from last year
lets look at luminus cxm22
160W:~33 ppfd/w
80W: ~39 ppfd/w (+18% compared to 160W)
40W: ~43.5 ppfd/w (
+11.5% compared to 80W)
20W: ~ 47 ppfd/W (
+8% compared to 40W)
20-100W is where 95% of cobbers run these chips (and that would pretty much scale with any chip which all have their ranges, and where growers would operate a given one), so again , 8-12% gain when halving wattage (call it 10% as a rule of thumb)
as you can see the dropoff is steep at very high currents which is wy we dont use them up there.
FWIW 160W is well over the cxm22s max current, which is 2200ma/125W per datasheet (but i measured it up to 3.6A anyway)
