We learned yesterday that star soprano Patricia Racette had to withdraw from singing today in the Verdi Requiem at the SF Opera house, and will be replaced by Adler fellow Heidi Melton. Racette, a recent hit in Madame Butterfly, was to sing the Requiem for the first time. No disrespect meant to the up-and-coming Heidi Melton, who will nail it, but that's a bummer. Racette and Stephanie Blythe, that was a spectacular tag team. Nonetheless, the SF Opera orchestra and choir, under the baton of departing music director Donald Runnicles, will be on the stage for once, not in the pit. That should be an exciting farewell to the maestro.

The Artist's Vocal Ensemble will explore Californian music on Friday (in Berkeley) and Saturday (in SF). We thought that meant the Beach Boys, but what do we know, they actually look at "the musical styles that have influenced our musical palette in California." They are accompanied by jazz saxophonist Daniel Zinn for "an adventurous meeting of old (medieval polyphony) and new (jazz improvisation)." We always find Renaissance motets surprisingly modern; this proves they're only a short step away from jazz. Program includes some Poulenc, Vaughan Williams and others.