TK's Emisar D4 review

High CRI always comes at the cost of efficiency. So your findings are true and they were predictable.

If cri is not important for you the lower cri SST20 LEDs would have been a much better candidate as they are way more efficient while rivaling the XP-L HI in output and beating them in throw.

I personally prefer High CRI but dislike the green in the SST20 4000k variety.

Running some very rough numbers with lots of assumptions gets me this:

  • D4 SST-20 6500K, spec’ed at intl-outdoor at 4200lm. That is 1050lm/led, so about 1280lm for the bare led, which is at 86% of max and they run at about 4.5A per led.
  • D4 XP-L Hi, spec’ed at intl-outdoor at 4300 lumen, that is 1075lm/led, so about 1310 bare led lumen, which is at 62% of max, and they run at about 4A per led.

So the XP-L Hi version runs 2A less in my calculation while putting out a bit more light. The experiences above suggest a larger current difference though, so something is off, perhaps int-outdoor’s specs or my numbers :stuck_out_tongue:

Regardless of CRI I find the SST20 to be much worse. In my D4, the SST20 is noticeably inferior for my needs in the most basic test: output.

  • The SST20 D4 ramps down much faster than my D4. I like burst modes, but in the D4, the SST20 starts out with a slightly brighter hotspot, but within 10 seconds of turn-on it is already much dimmer than a D4 with XPL HI.
  • SST20 might be more efficient, but what’s the point if I’m not able to take advantage of that efficiency and see results in-use because of the higher heat generated.
  • I hate greenish tinted lights. I find tint of the SST20 at anything less than max turbo to be unacceptable.

My modded D4 looks pretty, but has the worst possible configuration for heat management. It is more susceptible to rampdown from overheating than probably any other D4:

  • Polished Bare aluminum head (not as good as copper at transmitting heat and can’t hold as much as copper. Shiny bare aluminum has lower emissivity than dark anodized aluminum).
  • Titanium body tube and bezel (not as good at transferring heat from the head as aluminum.

It is possible that a stock aluminum D4 wouldn’t see such an extreme difference in results.

yes, of course. Sans the tint these are direct results of the High CRI variant being considerably less efficient.

Your reasoning that these are not a good choice for your needs is sound.

I was merely saying that this outcome could be expected and people should only choose high cri if they appreciate the better cri so much, that they are willing to accept the impact in virtually any other area of LED performance.

Agreed.

For those who absolutely must have high-CRI in their flashlight and who don’t care about other factors, the SST-20 is a good choice. It offers considerably higher output at high-CRI than most other LEDs on the market.

It might also be a great choice of emitter for small single-cell throwers like the D1 or D1s. With only one emitter, plus more thermal mass, those lights are much more likely to be run at max power. And max power before rampdown is where the SST-20 truly shines.

I had gotten the high CRI SST-20’s in my E07 due in part to no additional cost and planned on replacing them anyway. I got a Manker E14 today with 2 ruined Nichia emitters and so I replaced the Nichias with 4 of these 20’s.

At low output the green is excessive. At higher power level it clears up quite nicely. On a VTC5A it pulls around 50A at the tail. Pretty big draw on these small emitters! Not that Luminus emitters are known gor high efficiency…

Definitely a tighter beam that part is welcome, lower modes are virtually useless for me though.

I wouldn’t say excessive.

It’s extremely hard to find emitters that have good rosy tints below 350mA for LEDs* due to how photon emission at different wavelengths work, but it depends on the tech used in the LED and the tint bin.

Basically, the tint shifts to green at low currents in LED emitters since the blue light emitted from the die can be more efficiently converted to green compared to red colors.

It gets better for high CRI LEDs and lower CCT LEDs, but the problem still presents itself. The closer you are to perfect color reproduction(akin to the sun), the less this issue arises at lower levels.

That’s why at the same color temp and same tint curve deviation, an SST-20 4000k 95CRI can look better in the tint department compared to an LH351D 90CRI.

*That only works for LEDs. For HIDs, and incandescents, it’s the complete opposite. The LES gets rosier as the power draw gets lower.

I notice a little green in my SST-20 4000k 95CRI when next to my 5000k XP-L Hello.
On its own I don’t notice any. My mind could be blocking it, like a bad experience.

But I DID use the word excessive because I do NOT like what I shine a light on to look green. Not our brownish cream colored floor tiles, not our beige carpet, not my son or anything else I look at. Green is an absolute no go for me, period and end of that story. So this E14 that just came today will get the emitters swapped again ASAP tomorrow.

All 7 of the SST-20’s that I removed from my E07 will be in the trash probably less than 12 hours from now. (as it’s bedtime here and I have something that I have to take care of first thing in the morning)

Edit: For reference I ordered my E07 with 5000K NW SST-20’s

I think our eyes are just different, or perhaps the tints of certain LEDs are just worse than others even in the same tint bin.

Don’t forget, I’m a photographer and I deal with processing colors correctly in a very big way. Thousands of pictures at a time from a full frame Canon sensor on a professional Dell monitor that’s color corrected. Proper color is very important to me, it’s a way of life.

Green is a no go for me also.

My 4000k don’t make my kids look green :slight_smile:

@DB Custom, ahhh.

You didn’t say you had 5000k 65CRI SST-20.

These actually have slightly worse color rendering than even XP-L HIs.

The 95CRI 4000k SST-20s are another completely different world.

A photo of my daughter, printed on Kodak Metallic Paper at 24x36. These pics taken moments ago with my i8 locked at 4352K and with 2 lights at approx the same output. Bet it doesn’t take you much of a guess as to which one I’ll be throwing the emitters away…

FWIW, the emitters in both lights are 5000K

Holy crap, these are the greenest emitters I’ve ever seen.

These look almost as bad as XHP50.2/XHP70.2s.

Luminus really should’ve made 5000k 95CRI SST-20s, huh, or even 5700k?

Luck of the draw perhaps. But yeah, they didn’t stay in my E07 very long at all. The nice tint, on the left, is the E07… with LH351D 5000K W6 emitters.

Beam profile is nice, Turbo tint is nice, but at lower output level just a fail on an FET driver. Maybe I’ll try em on Neven’s regulated driver and see how that goes, probably the same though…

I ordered the 4000K 95 CRI SST-20’s in the PL47, didn’t like those either, gave the light to my Son-in-Law for Christmas. :wink:

Plus One and Wow.

I didn’t compare heat or amps or runtime, but when I compared tint of SST-20 4000K 95CRI to an XP-L HI 5A/5D, I found the XP-L HI made a much nicer-looking beam despite the lower CRI. SST-20 looked fine at high levels, but I don’t use high levels very much.