@djlink I think that kind of tone (as opposed to a short clack) sound was typical of aperture grille (trinitron) tubes.
In the 90's, my parents had a 27-inch (or close to that) Sony Trinitron TV that made such a loud roaring sound on startup that would scare your cat.
Something like this:
@carlosefr @djlink that's a powerful one, relay powered, not like the other wimpy PTC regulated