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 2x1700K and 1x4000K 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.
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?
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.
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).