I've never associated brass drums with a shrill sound. It's got to be the phenomenon where your ears perceive them differently. I don't know what else it could be, besides a bright-sounding room, but I'm sure you've accounted for that.
The Black Beauty has a bright component to the sound, but it also has depth and warmth. I don't hear a thin sound either. There could be other make/model of brass snares that fit this description, but I can't think of any.
My idea of a bright and thin sounding drum would be a thick stave shell. It would be super loud, yes, but also bright and thin at the same time.
This idea of people hearing different things is intriguing.