There is a firmware sub-version in her repository for anyone who wants to be conservative with the 219B. It limits the FET channel to 50%. It is also possible to create your own firmware version with different ramp levels.
Because the red XP-E2 has a low forward voltage (and the photo red and far red even lower still), it is probably advisable to avoid FET use entirely unless you’re willing to risk killing a set.
On the other hand, the red and green XP-E2’s seem to have fairly high foward voltages and might work ok with FETs.
Source - XP-E2 datasheet, plus DJozz tests:
[image] These tests were done already a month ago (sorry for the delay), but tonight I was finally in the right mood to type in the data, make the graph and do this write-up (I like the testing itself but it always takes some courage for me to digest the numbers and make them into edible graphs :tired: ). Thanks go to MRsDNF for donating me the red and blue XP-E2 (from Cutter, red is bin P3, blue is bin M3), and to telephoneman for the green XP-E2 (from Mouser, bin is R2), they were not easily …