[Review] 5700K CRI95+ COBs from user rngwn

Joshk · 2019-09-18T21:46:36.000Z

I’ve been needing some excellent lights that I can use for photography and also a work-light. I know work-lights usually don’t need to be great, but I often spray paint in the backyard after dark, and great lighting is a must for that.

I’ve built 2 lights with some of the highest praised LEDs on BLF:
Triple “Nichia NVSL219BT D220 4000K 90+ CRI LED” from MtnElectronics
Quad E21 “NVSWE21AT 5000K sm503-D240-M1-R9080” from Virence

Now, the great test results quoted for these lights are always for low power, say 700ma. I had been assuming since I haven’t seen test results for higher powers, that there wasn’t a noticeable difference. I was wrong. The lights I built perform great when run at low power, but go to heck when I go up to 2 amps.

After building the 219b triple I was split between some COBs on a WTS from a new user “rngwn”, or some E21’s from Virence. I chose the E21’s because the COBs had no reviews. Well after the E21s disapointed me, I wanted to give up. I felt my endeavor was just bleeding money. Eventually I reached out to rngwn and asked if he would be willing to send me a pair in exchange for a honest review. He accepted, and this is that review.
Here is the link to his WTS thread where he is selling them: Budget 5700k CRI 95 100w COBs [Items in Stock]

They shipped from Thailand and arrived on day 20 after placing the order. They came packaged well enough. It was a plastic mailer with the COBs foam-wrapped together inside. Stapling the thin plastic mailer shut seemed risky compared to just taping it, but he said their post office tells them not to use tape.

I mounted the COB on a what I call a “Headlight”. It’s a CPU cooler inside a red mounting ring. This lets me bolt it to things like my custom built light frames. Or even just a tripod. It has a 1/4” threaded hole.

I did a chip test. That’s when you use low power to make all the LEDs on the COB glow and compare the brightnesses. I was pleasantly surprised to see they were all quite even. Only one near the middle was a tiny bit dim. And dim is really no problem. If one was too bright, it would burn out later and kill a whole row of LEDs.

Like with all LEDs, the point you measure the output from matters. For all the readings I put the meter 1 foot in front of the COB and at a slight angle of 10 degrees. With the emitter bare I got these numbers:
CCT: 6283
Duv: –0.0016
CRI: 96
TLCI: 98

From straight-on the CCT goes up about 200 and from a near 90-degree angle it goes down about 200.
That’s a lot higher CCT than the advertised 5700K. rngwn said that the seller actually listed them as 5700-5900K. That was news to me.

So I made a reflector and covered it with D-C-Fix in hopes of pulling warm light from the sides and correcting it.

The CCT was still cool at about 6125K, but the Tint, CRI, and TLCI numbers are excellent and consistent for all power levels! Yay!
—0.25A 26.5v— (6.6 watts)
CCT: 6191
Duv: 0.0008
CRI: 97.3
TLCI: 99

—0.50A 27.02v— (13.5 watts)
CCT: 6156
Duv: 0.0006
CRI: 97.7
TLCI: 99

—1.00A 27.75v— (27.8 watts)
CCT: 6149
Duv: 0.0002
CRI: 97.6
TLCI: 99

—2.00A 28.88v— (57.8 watts)
CCT: 6101
Duv: –0.0005
CRI: 96.6
TLCI: 98

—3.00A 29.80v— (89.4 watts)
CCT: 6090
Duv: –0.0008
CRI: 96.0
TLCI: 98

—3.34A 30.10v— (100.5 watts)
CCT: 6075
Duv: –0.0008
CRI: 95.7
TLCI: 98

Now if we plot that we see that they are very well clustered and neutral along the BBL. Perhaps being up along the Daylight Locus would be better? IDK. But no LED I have tested to date is up any higher than this.

Conclusion:
I am very impressed with all the metrics except the CCT. Luckily CCT is one of the few things you can fix. I ordered some filter plastic to drop the CCT from 6125 to about 5625. That is inline with the daylight coming in my windows so there will be no wierdness in my photos. I should also be able to double the plastic and get down to about 5125 too if I like, but that might make a lot of heat.
It’s also very bright, putting up brightness numbers at 1 foot distance that are about half of today’s daylight. That’s pretty good since I am not focusing the light into a beam.
All in all, these things really delivered for me. So last night I placed an order for 6 more of these COBs.

Check out the complete data here:
COB Review Data.zip

Joshk · 2019-09-18T23:27:43.000Z

Any opinion on the Black Body Locus vs the Daylight Locus at this CCT??

DavidEF · 2019-09-19T01:12:41.000Z

Joshk:

Any opinion on the Black Body Locus vs the Daylight Locus at this CCT??

So… Daylight Locus is greener than the Black Body Locus? That’s an interesting factoid, I guess.

maukka · 2019-09-19T06:16:52.000Z

Thanks for the test! Interesting that your sample is well above 6000K while mine was closer to the advertised value when measured directly above.

Joshk · 2019-09-19T12:24:24.000Z

Yea that is interesting. Were you testing it bare-emitter or using some optics?

maukka · 2019-09-19T18:04:36.000Z

Bare.

Lightbringer · 2019-09-19T20:35:17.000Z

DavidEF:

So… Daylight Locus is greener than the Black Body Locus? That’s an interesting factoid, I guess.

I always thought so. That’s why the typische 4Cs that come with some S2+es are “greener” but to me seem more like natural daylight vs 4As or 4Ds. I always said that behind a TIR lens, a 4C is like “warm sunlight”.

’Though I wasn’t really a fan of 219Cs, oddly enough. Nice enough, don’t get me wrong, but I still prefer the rosier Bs.

Joshk · 2019-09-19T20:40:40.000Z

There’s actually a locus called the TM-30-18 that merges the BBL and the Daylight Locus. Very cool.

Joshk · 2019-09-20T04:55:59.000Z

This isn’t really worth a new thread, so I will leave it here for reference… After I tested all the LED bulbs in my house that I bought from Lowes and Home Depot over the years, they consistently had a CRI of 83 to 84 across all brands. The Hyperikon I got from Amazon are a CRI of 92 to 93. Duvs were mostly all positive in the 0 to 0.003 range for all lights, with the Hyperikons again being the best.

iamlucky13 · 2019-09-20T05:03:21.000Z

Nice test. Aside from being a bit cooler than specified, very impressive results for such an inexpensive, high power COB. I don’t have any uses for one at this time, but seeing how well they perform is making me try to think outside of my normal uses. At a minimum, I hope rngwn is able to find more takers for the COB’s he ordered.

These seem like potentially really good video or work lights.

Also, I appreciate the info about bulbs. I suspected most have a slight positive duv, but so far, it hasn’t been enough to bother me.

rngwn · 2019-09-20T13:52:12.000Z

Getting my inventory moving is of course, essential.

The manufacturer said they have prepared a possible upgrade (efficiency-wise) to these COBs for me (of course, at higher price point), but we both wait to clear this stock so I first recover from the investment (This may or may not happen in the short term).

Joshk · 2019-09-22T16:14:55.000Z

Well I received the CCT correction plastic. It shifted the CCT from 6125K down to 5318K. I consider perfect to be D55 (5500K) so I sanded the plastic film down a little thinner. That got me to 5464K. That’s excellent! Heck, if I bought a $200 studio light from Amazon, they often state +/- 200K. And I’m within 36K!