Interested in E21A for <2700k CCTs and there are 2 routes I can see.
First is the Emisar quad light, with 4 emitter spaced out.
Second is eurekatronix MCPCB with 4 emitter tightly packed together.
I prefer euraktronix because you have more possible hosts, could be built more inexpensively, there are also more options for lens, in fact there is only a single carclo lens that suits the quad E21A Emisar.
But I could not find a single build with this.
The E21A (and E17A) is bit unique and might be only example of 4 emitter closely packed together,
so I wonder is there any real difference between it and the typical spaced out quad/triple arrangement or it’s the same thing achieved different way?
A quad e21a packaged together has a gap and will create a dark spot in your beam unless sufficiently diffused. If you want a quad e21a, you should look at the B35AR that is 4 e21a LEDs without the gap. It can be retrofitted to any Xhp35 12v driver flashlight, or xhp50 if not driven too hard.
Don’t underestimate the e17a in quad package from Eurekatronix. I have two skilhunt H04RC headlamps with e17a quad and it’s fantastic. Way more intensity than the floodier e21 quad with négligeable drop in output/efficiency.
In this case efficiency will be the same as it always 4x e21a, I did wonder if the tightly packed e21a could also have potential to throw more with the right lens.
I seen B35am but it does not come in 2000k unfortunately.
I hear about darkspot but I think that has still got a much bigger problem for the typical triple and quad lights, hence the single only suitable lens for emisar e21a?