>>is there a minimum level to get it to work?<<
Oh, I didn't have it bard sung, so I'm not sure. The character that found it got it off a critter in the Bowels. She's 94, so presumably she meets any level requirements for activation; what I did was check her stats, skills, and then use the Hanging Inn crystal to look for stuff like flares and weighting.
The bells of Hell
go ting-a-ling-a-ling
for you but not for me