Requesting help with identifying a science fiction movie that I saw once as a kid during eighties (so it could be older than that). I remember just a few scenes, and I am not certain about the accuracy of these descriptions.
The only scenes I remember were happening inside some control room that is located inside a house or a castle of sorts, and which was translated as "citadel" in Croatian. Considering "citadel" is not a Croatian word, I suspect it may have been called "citadel" in the original language as well. (I assume the film was in English, but I am not sure.)
There was a robot in the movie. Humanoid in shape though bulky, hands are flexible (like tubes), not very intelligent, not aggressive, somewhat slow in motion.
The most recognizable feature for me was a "weapon" of sorts. It was located in the middle of some room (like a control room). It consists of something like a crystal on a rotating axis, and when it gets to a high rotation speed, it produces a loud sound that paralyses any humans in the room. There was a helmet that protects against that sound; it was transparent like glass, hemispherical in shape, and it could be just placed on the head to protect against the sound. I remember a scene where one male character puts the helmet on and turns the crystal rotation on, to paralyze the other male in the room. I think that happened near the end of the movie, and that the "attack" was unsuccessful; the second male managed to wrestle the helmet off the first one, and turn the sound (crystal) off.
The last scene I think I remember is the "citadel" being destroyed in some kind of seismic event, an earthquake or a volcano or such.
Unfortunately, it is not much, but that's all I can vaguely remember (I've been Googleing for it for years, no luck thus far. I'll appreciate any help!)