There is a story, the kind that only happens in jazz, that goes like this: One night during a concert, a frenzied crowd was going nuts for the off-stage trumpet tones they assumed were coming from Louis Armstrong, the man they had all paid to see. Little did they know that Adolphus Anthony “Doc” Cheatham was the source of the sounds. Now, at age 89, Cheatham can claim to be the last important trumpet player to emerge before Armstrong. The short list of people whose music has been graced by Cheatham’s brisk, tight trumpet spans the history of jazz: Jelly Roll Morton, Cab Calloway, Billie Holiday, Benny Goodman, Machito, and Tito Puente. Since the late ’70s, when Cheatham finally began leading bands, his stature has continued to grow along with his abilities. Cheatham’s trumpeting is still strong and vibrant, and when he sings, the strength and vibrancy he exudes extend far beyond trumpet playing. At 10 p.m. & midnight at One Step Down, 2517 Pennsylvania Ave. NW. $13.50. (202) 331-8863. (Chip Porter)