I fear that the E21A would give handling problems when reflowed by flashlight manufacturers, it is a delicate operation and I’m pretty sure they have no pick-n-place machines at Sofirn.
I’m all for the SST-20-W led, at these drive currents it is not that much less efficient than the LH351D. I think though that a few people regret that the colour temperature will not go up to 5000K anymore. Btw, I had understood from Barry (from a different discussion) that Sofirn is able to source the high CRI SST-20 leds.
LH351D diffuse really well as it is. Even though SST-20 may work it seems like a compromise in every regard. Efficiency, CCT, and beam shape. Makes you wonder what is truly going on with Lumintop and Sofirn with some of these projects…
Yeah, I was really wanting the lantern to go a little higher than 4000K for sure. However, since it’s a lantern and not a flashlight, I think 4000K would still be acceptable.
If SST-20 is considered, 5000K is a very big step back (available only in ~65 CRI instead of ~95 CRI). If only SST-20 is used, this should be kept in mind.
Has anyone made more progress with throw numbers before/after slicing? I’m curious whether it’s worth the risk, or if these things are “good enough” with the tiny little dome on. I’d love to have some options that came even remotely close to the Oslon White Flat for throw with warmer CCT and better CRI.
@coherent, you’re asking about the sst-20 in general or in this particular light? I just happen to have pre & post slice throw numbers from an single led / reflectored light I built with an sst-20 two days ago if you’re just looking for general info.
Dome on the throw was 17,500kcd, after the slice and refocusing the little light was doing 33,200kcd. Tint and lumens both dropped ever so slightly.
Cereal_killer, I was curious about the SST20 in general, so your numbers are perfect. Nearly double the Cd and 40% more throw, sounds like I need to buy a few extras to try slicing. Do you have any advice for getting a good, clean result?
Sorry just saw this, I did the washer method. Slice with a fresh new blade that you scrub with alcohol before using.
To be honest, had I spent the time focusing the emitter pre-slice that I did focusing it post-slice the difference would be less dramatic. I probably could of got the domed emitter focused a good bit better, just an amature best guess here but I’d say, if I was as meticulous with it as I was the sliced one I probably could of gotten it so the difference was <25% increase instead of nearly 50%.
I only spent 10min focusing it the first time around, only a few tries sanding the disk. I had set a goal of 40kcd for the light and I could see I needed something dramatic so I did the slice before spending much time on it.
Oh I forgot, I came back to this thread to ask what my options were for 5000k SST-20’s currently for sale in the highest output bin (the base 70cri version will be fine for this one)?
I have a 3500K SST-20 from BlueSwordM/Mouser in my Emisar D1S right now. Using a GA (being conservative) it makes about 680 lumens and 595m throw vs. 1020 lumens and 665m with the stock 5D XP-L HI. Tint is acceptable and everything on the trail looks much, much nicer thanks to the dramatically better CRI (especially R9).
Today I tried a couple of slice dedomes. The first one went fine, but the second I shaved a little close and clipped a bond wire, which melted the moment I turned it on. With the “good” dedome, output is 30% lower (470 lumens) and I gained a grand total of 5m throw. The hotspot is much smaller and there is less corona, and subjectively the tint is a lot rosier. It’s possible I would gain more throw by playing around with the focus, but I don’t have the material to do it here right now.
The effectiveness of slicing is sensitive to the thickness of silicone remaining over the die. If it’s not very thin light can reflect off the silicone/air interface and bounce down to the side of the die where it’s more likely to be lost. This reduces the output and reduces the throw gain. If the silicone is very thin this reflecting light will bounce back to the die where it increases the die luminance.
With some of these LEDs the bond wires are tall which makes it harder to get a close cut.
A theory: the reason that by slicing a warm/high CRI led you loose so much output (20+% compared to 10% for cool white)is that there is much less blue light to be recycled to turn into more visible green, and at the same time phosfors are present that recycle green into less visible red.
I have not fully thought this over, but I have seen with the spectrometer that when a high CRI led is illuminated with 530nm green light, apart from scattered green you can measure some red coming off the led.
I discovered that after a couple more attempts. Shaving it so thin I accidentally took off a bit of phosphor on one edge got me up to 715m throw. As you know from your own attempts you need to give the bond wires a wide berth because they stick up so much, and I’ve managed to ruin two that way so far. Working on #4 right now; wish I ordered more than 10 of these!
In any case this is a very promising LED for a high CRI thrower. 600m throw to start is quite acceptable, and increasing that another 100m with a rosier tint is the icing on the cake. I think it’s just a matter of grabbing half a dozen and trying for the best slice possible.
Slice #4 got me 670m throw with no damage to the phosphor, which I’m quite happy with. It has always bothered me that no matter how many boutique high CRI modded lights I carry, I’m still stuck with a CRI 70 thrower that washes out everything in nature. This SST-20 is throwing just as well as the stock XP-L HI and looks way better out on the trail. I look forward to acquiring a nice tint bin in 4000K which will match my other lights better and probably throw even further. Next up is seeing whether it can handle a VTC6 when it’s pulling 5.5A off a GA, but I’ll be using the trimmed phosphor sample for that!
Here’s the first bond wire that melted if anyone’s interested.
I tested a SST20 5000k in a C8+ at 2.8A and measured 550m throw (less than the stock xpl hi)
Then put a SST20-W 4000k and a LD-A4 driver at 5A: I measured 500m throw
the 4000k needs 2A more and still throws less than the 5000k, a XPL-HI V2 5D will outthrow the 4000k SST-20
Maybe I’m not paying attention to CRI but is it worth to lose such amount of light for a better CRI? the LH351Ds are 90CRI and are similar in brightness to the XPL/XPL2
I had a talk with Sofirn a few months earlier about how high CRI can be good.
