I bought a 4000K and 5000K CRI95 E27 LED spot bulbs from DIY LED U-Home on Aliexpress.
Store link: 12.04€ 19% OFF|Hohe CRI RA95 E27 7W COB Led lampe Lampe Led strahler Downlight AC85V 265V Warme Neutral Tageslicht Reinweiß für zimmer Küche|LED-Strahler| - AliExpress
The main specs by the manufacturer:
-CRI (Ra) 95
-Undisclosed COB emitters
–650-700 lumens
–7W power draw
-Wide AC voltage range of 85-265V
-Available in 3000K, 4000K, 5000K and 6000K (4000K and 5000K tested here)
–45-60° beam angle
-No dimming
-No lifetime specified
-Unknown warranty
Overall finish and build quality seems good. The aluminum heatsink is painted white and it doesn’t take much to scratch it off. I don’t like that you can hear the AC-DC converter rattling around in the base when the light is shaken though.
The spotlight compared to a 60W incandescent.
The bulb has a plastic lens protecting the COB LED and reflector. Wide and even spot is achieved with a textured reflector. There very little visible tint shift in the beam. Only very faint artifacts can be seen on a white wall at the edge of the beam.
When you put a table lamp shade on it the artifacts disappeared. I used an Ikea Tertial work table arm.
Measurements
Measurements were made in a 50cm integrating sphere with an x-rite i1pro spectrometer after the bulbs had warmed up for 1 hour. Intensity (lux at 1 meter, candela) was measured outside the sphere at 1 meter.
The bulbs were connected to mains power which at the time of testing was at 228-230V.
Output at 1 hour is 574 for the 4000K and 593 lumens for the 5000K model. This is less than the manufacturer specifies (650-700 lm). At 0.6 cd/lm the spot bulb is noticeably throwier than a diffused bulb (0.1-0.2 cd/lm)
Power consumption was measured at 7.1 (4000K) and 7.4 watts (5000K). Efficiency is quite low for a high CRI neutral/cool white AC bulb at only 80-81 lm/W. Yuji BC bulbs achieve 104-109 lm/W at similar color temperatures, but they also cost twice as much.
Maximum output is reached immediately. Output was plotted over one hour on both lights. After 1 hour the output decreases 11%, which is a fine result for such a small bulb. Heatsinking seems good.
Color rendering
The CRI data was measured integrated after a 1 hour warm-up.
Color rendering is very good on both bulbs reaching CRI Ra of 98 and R9 of 92-93. TM-30-18 fidelity index Rf of 94-95 and gamut index Rg of 99-100 are also excellent. Typical LED technology is evident from the blue hump at 450nm and cyan dip at 480nm, but the latter is very mild. Visually the light is very pleasing with rich colors and neutral tint.
Load IES TM-30-18 Color Rendition Reports by clicking the thumbnails:
CGATS CRI Data files:
4000K: DIY LED U-Home E27 COB Spot 4000K - Pastebin.com
5000K: DIY LED U-Home E27 COB Spot 5000K - Pastebin.com
Color temperature and tint
Tint is practically at the black body line on both bulbs. Remember that when LEDs heat up, their duv value almost always decreases and becomes less green/yellow. This was measured after 1 hour.
Tint shift was measured with the 5000K LED after a 5 minute warm-up period. Shift is very slight within the brightest part of the beam which falls off quickly after 55 degrees or so. The shifted tints in the following chart at 60+ degrees are already outside the bright spot.
Flicker
There’s no visible flicker. Just small ripple at 56kHz. Snob index of 0% guarantees that it’s easy on the eyes. The modulation depth was highest when all the LEDs were active, which as the worst case is shown below. Both lamps are identical in this matter.
AC power draw
Current is drawn in short pulses as the input voltage gets high. This results in a low power factor of 0.56-0.57.
Cyan line: mains line voltage
Yellow line: current draw of the bulb
Violet line: power draw (voltage * current)
Verdict
These little E27 spotlights at 4000K and 5000K have a pleasing tint and good color rendering. They offer quite a bit more lux at a smaller area than diffused bulbs. The efficiency is not at the level of competition, but that’s quite ok for the price assuming the driver ages well. In packets of five they cost less than $9 a piece.
Please note that the test was done when the bulb was brand new. I can’t guarantee that they will perform similarly after months or years of use.
