I'm a car guy, and this has me infinitely amused, as it's an eternal automotive comedy routine: "Well, does it sound like this? [makes a weird noise]" "Well, no, it's more like [makes an even weirder noise]!" "Well, is there sort of a [yet a stranger noise] to it?" "Well, no, it's got a sort of [gets spit on the other guy's glasses] overtone!" and on and on into the night...
How long does this noise last at startup? Does it stop suddenly, or just kinda 'go away' gradually? Does it sound mechanical (like, maybe, a fan wire getting 'buzzed' by the blade, or is it more of, say, an electronic noise (yeah, and how the hell do I define that) like a speaker or a buzzer of some sort (which might be a slightly loose inductor charging up)?
Looking forward to your next post - this sounds (no pun intended) like it'll be fun!
Bill