Various lights and mods using the Seoul P4 LED:

With a slight modification for optic alignment, the Seoul P4 can be retrofit in a luxeon based light. The sink slug is anode and needs to be electrically isolated from the circuit.

Beam shot above has a Cree XR-E LED in light on right compared to similar host with a Seoul P4 (which uses the same Cree EZ1000 chip).

In the beam shot below (top to bottom), the same converter drives a Luxeon III, Cree XR-E and Seoul P4 behind the same 27 mm reflector which has been modified for focal adjustment.

The primary difference between the output of the XR-E compared to the P4 is that of distribution of light. The XR-E has a narrower viewing angle which puts more of the light out of the front and unaltered in course by the reflector. The P4 has more light managed by the reflector and greater concentration of light in its center beam with less in the spill portion.

The larger 38 mm reflector of an Aleph 3 shows the difference more clearly. In the beam shot below, a XR-E is in the top Aleph 3 and the Seoul P4 in the bottom Aleph 3. The top ALeph 3 has a deeper bezel ring which reduces the diameter of the spill portion but has no effect on its intensity which can be seen to be greater than that of the Seoul. The Seoul on the other hand delivers more light and intensity at its center.

Seoul P4 in a Titanium PD (PD-S) taken for a swim:

Ink Test: