I used to have two F-1X preamps, but I do not recall whether it is multi-voltage or not. Multiple taps are separate wires going into the input side of a power transformer that allows for re-wiring depending on the AC (100/120/240, etc.) of a particular country.
I didn't notice that you were not in the US. Perhaps an e-mail to Alembic, they have always been very helpful to me in the past, even when I just happened to drop in on them with no notice to get a tour of the place. I happened to have some extra time while I was in the area on vacation a fews years ago and Mica took my wife and I around.

I have some nice photos of it, too.