There's no shortage of bar bands out there sleepwalking through blues changes and soul covers, but a tight band of true believers is increasingly a rarity. The long-lived Butanes play blues and Southern soul for hardcore fans, and tend to convert some dabblers in the process. Leader Curtis Obeda's leads recall Albert King or Otis Rush in terms of improvisation panache and pure volume, while his spare R&B rhythm playing would make Steve Cropper smile. He's got a sideman's singing voice, but he gets the job done, belting out well-chosen tunes with humor and soul. The rest of the band is similarly assured. Virgil Nelson plays slightly conservatory-tinged blues on Hammond B-3 (the real deal, with Leslie speaker oscillating behind him), bassist John Lindberg is always in the pocket and justifies his occasional solos; while insouciant drummer Robb Stupka impresses with subtle flourishes and a smart, no-flash policy. Sometimes the core Butanes quartet is augmented with horns, and things really heat up when Willie Walker, a little-known but grade-A Memphis soul singer and local hero, drops by to sing vintage R&B and Obeda originals. Look for a second Butanes-Walker collaboration in the near future, and check the club listings for the next Butanes gig. They're probably playing tonight.