When it gets good -- really, really good -- with Mavis Staples -- and it often does -- you can surely tell it. That robust, guttural voice ceases, her face bursts into a big smile and then she starts preaching. She recites the lines of the song she's just concluded as if she's delivering a sermon.

And in their minds, the clapping, whooping concertgoers are thinking, "Amen!"

That happened several times Wednesday at the jam-packed Dakota Jazz Club because Staples was really, really good.

At age 70, the queen of Chicago soul, a Rock and Roll Hall of Famer and one of America's great musical treasures still has it. She may not have access to her high notes, and her lower register sounded a little rough at times, but she delivered what she'd promised near the start of her 95-minute performance: "joy, happiness, inspiration and some positive vibrations."

The set was heavy on spirituals and songs from the civil-rights movement and light on the hits that landed the Staple Singers on the radio and pop charts in the early 1970s (we got a sing-along "I'll Take You There" but no "Respect Yourself").

Staples stirred it up with her gritty growl on "Wade in the Water," delivered "Waiting for My Child" with a soul-stirring whisper and turned "Why Am I Treated So Bad" into a swampy, bad-ass gospel -- if that doesn't sound sacrilegious.

Say "Amen," somebody.

JON BREAM