Review : 1700K LEDGUHON COB Ra>90 test and tint mixing with 4000K Sunlike SOL

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thefreeman
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Review : 1700K LEDGUHON COB Ra>90 test and tint mixing with 4000K Sunlike SOL
I bought 3 1700K Ra>90 COBs from there for the purpose of tint mixing

Tint

100mA, 300mA :

100mA, 300mA with a lightbulb diffuser :

Not a very pleasant light, too warm, very orange.

Color rendering

Not sure why TM-30 metrics are so bad while CRI ones are good, probably a very different way of calculating at this very warm CCT.

Current/Vf

Just a quick measurement to check if they could be paralleled with SOL Sunlike, the Vf is higher, which makes sense since the COB area is smaller.

Tint mixing

On to the main reason I bought those very warm COBs, mixing sufficiently spaced CCT allows to make a light with less green, i.e. more ”rosy”.

I was aiming at ~2700K with -0.0050 duv and this is achieved with 2×1700K and 1×4000K in parallel, the current is not extremely unbalanced.

Sorry for the measurements at different currents there.

Tint mixing color rendering

It increases saturation of all colors except blues which have a bit of hue shift. This is quite good since slightly increased saturation is usually desired.

Edited by: thefreeman on 11/06/2020 - 19:10
cetary
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Maybe a Lee minus green to push the duv of that 1700K COB lower might do the trick? Maybe allowing the COB to heat up on a slightly poor thermal substrate might help to?

SKV89
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Too bad for the positive duv. Will look way too yellow/orange for an ultra warm CCT emitter.

Robin Dobbie
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cetary wrote:
Maybe a Lee minus green to push the duv of that 1700K COB lower might do the trick? Maybe allowing the COB to heat up on a slightly poor thermal substrate might help to?

thefreeman recently tested lee minus green filters and they didn’t even last a day.

Another thought is I would’ve thought that’s already not the best thermal situation with the cobs half-off the main heatsink. But I guess it’s still a lot better than the way they make these silly lights sometimes. Only problem is they don’t last.

thefreeman
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The weird positioning was just for the tint mixing measurements since I didn’t have enough properly placed mounting holes to place multiple COBs on the solid aluminium and I was too lazy to make more… but it didn’t make noticeable change about tint.

lightdecay
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Are there any products that use this COB LED? I want to buy something to see if I like the light or not.

cetary
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Robin Dobbie wrote:
thefreeman recently tested lee minus green filters and they didn’t even last a day.

Resource?

lightdecay
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cetary wrote:
Robin Dobbie wrote:
thefreeman recently tested lee minus green filters and they didn’t even last a day.

Resource?

Lee Zircon minus green filter lasted longer than a day, but there was noticeable degradation too.
https://budgetlightforum.com/node/75045
Robin Dobbie
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I guess the filters are designed for movie studios who have relatively unlimited funds and regularly change them out.

Any kind of measurable degradation in a day, that continues, tells me I should never bother trying to fix color with a filter for a light fixture that’s going to be on for hundreds if not potentially tens of thousands of hours.

Although I’m still curious how that minus green paint JoshK sells holds up.

SunLike
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Hello Hat

About LEDGUHON

I use 5050 leds with 4 crystals (red 660nm and blue 445nm) from LEDGUHON, and some of 3535 leds

It is my lamps with LEDGUHON LEDs:
6C


SunGrow16


SunGrow33

C80S

GrowBoard180


So, as you can see I use LEDGUHON leds in many of my models, but as SunLike LEDs from LEDGUHONNEVER!

They lie about power. If there is 10W, it mean maximum 10W in datasheet, so, real it is 5w (middle power)

If someone need, I have 2250k LEDs from SmartEcoLighting co.ltd (who produce SOL leds), I ordered it specially for my bulbs:

BelMORDOR’s Ламповщик|Lampman
https://t.me/sunlikenews

lbwnb
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I have two LEDGUHON cobs and several their 3030 emitters. I mean it look quite nice on paper but they certainly do not look as good compare to Sunlike or SOL. Besides, I am suspecting that LEDGUHON’s power is “absolute” max instead of nominal power, you can kind of tell from their light efficiency (50-60lm/w) is a sign for overcurrent (decreased power efficiency as violet based led normally have a efficiency of 100lm/w if not overdrived) Besides I tried several violet based emitters from other Chinese manufacturers, so far non of them except SOL (I ordered from their Taobao shop) are producing very satisfying color. (Probably due to positive DUV because of the slight cyan/green cast. Have to do intensive color mixing to fix this). So far Sunlike and SOL are in the same league. But the rest still have some issues. I hope that they can improve their product for future batches (lower the DUV).

If a LED emitter can die slowly, it can die quickly.