So I installed XHP50.3 HI into L21B. XHP50.3 HI is quite tricky to use with a smooth reflector due to its quad-die setup. If the LED is not focused in the reflector, it will result in an annoying dark spot at the center of the beam. The dark spot can be minimized but not completely eliminated in a smooth reflector. When the LED is perfectly focused in the reflector, the dark spot will be almost unnoticeable. After some trial and error, I determined that the proper reflector height for focusing the LED is 1.6mm from the PCB surface.
This means that there needs to be a 1.6mm gap between the bottom of the reflector and the PCB surface in order for the LED to be focused in the reflector. We need a 5050 gaskets for 9mm hole with 1.6mm thickness, we can achieve this by combining a 5050 gasket for 7mm hole with a round 5050 gasket for 9mm hole.
Here are the two gaskets that I used to achieve a combined gasket thickness of 1.6mm:
The left gasket is a square 5050 gasket for 7mm hole with 0.6mm thickness. The right gasket is a round 5050 gasket for 9mm hole with 1mm thickness. Both gaskets can be bought from the ‘Misc Parts’ section of LHT Flashlight Store in AliExpress.
Since the inner hole of the 9mm gasket is the diagonal of a 5x5mm square which ≈ 7mm, it will fit exactly on the square gasket which is designed for a 7mm hole. The fit is snug and there is no wiggle room between the two gaskets. The round gasket, however can easily rotate around the square gasket, which reduces the risk of detaching the LED from the PCB when tightening the reflector over a square gasket.
Here is the hotspot of the XHP50.3 HI in the L21B at a distance of 10m:
Reflector height is 1.6mm. A very faint dark spot can be seen on a white wall. However, the dark spot is not noticeable during normal use. The transition of the hotspot from corona to spill is very smooth, without any petals or bright rings as is common with square emitters in a SMO reflector.
Hotspot of the SFT-40 in L12B at 10m distance:
Reflector height is 1.4mm.
Hotspot of both LED overlapped so that you can compare the difference in size and features:
I took both lights out to see how well they work outside:
L21B XHP50.3 HI Beamshot:
I’m using the 6v 4.8a driver for XHP50.3 here, so the LED is being overdriven quite a bit. The beam has good throw and flood at the same time.
L21B SFT-40 Beamshot:
I’m using a 3v 8a driver for SFT40 here. SFT-40 needs no introduction, it really is the king of throw!
Beamshots overlapped to compare their characteristics:
The throw of this LED may not compare to the SFT-40 but that is because I am using a high CRI XHP50.3 here. A low CRI, high CCT XHP50.3 HI might exceed the SFT-40 in output and though it might not match the SFT-40 in throw, it will still be decently throwy; probably even more throwy than the SST-40.
L21B XHP50.3 HI 4500K 90CRI (Purple AR-coated lens):
The tint and color rendering of the LED is very impressive, maybe not as good as the 98 CRI Nichia 519a, but it’s significantly better than the 65CRI SFT-40. Also, the 95 CRI XHP50.3 HI is expected to arrive on Mouser pretty soon. I’m excited to see how they would compare to the critically acclaimed Nichia 519a.
L21B SFT-40 6500K 65 CRI (Purple AR-coated lens)
Overall, I would say that the XHP50.3 HI is a really good all around LED that is suited to a wide variety of situations. It has a good balance of light quality, intensity and output. Along with the XHP70.3, the XHP50.3 also has the best optical control of any multi-die emitter in secondary optics. Compared to other multi-die emitters such as the SFT-70, B35AM and GT-FC40, there is little to no beam artifacts and minimal tint shifts. The center dark spot which is commonly seen in the hotspot of multi-die emitters is the least obvious in the XHP50.3 and XHP70.3 LEDs, which makes it the easiest multi-die emitter to use with a SMO reflector.
