African-American church choirs have historically doubled as farm teams for soul hit makers–from Aretha Franklin, Al Green, and Sam Cooke to R. Kelly and Kirk Franklin. But the latest gospel musician to flirt with the big leagues isn’t a singer, and his chosen instrument is one of country music’s most enduring emblems: the pedal steel guitar. Twenty-three-year-old Robert Randolph is a lifelong member of the House of God church in Orange, New Jersey, where, as at 200 or so other such Pentecostal churches across the country, the pedal steel has been the lead musical voice since the 50s, when it was popularized by Philadelphia musician Willie Eason. Eason drew on Hawaiian music and country, but he also found that the instrument’s malleable pitch, eerie sustain, and liquid attack allowed it to mimic the human voice, and incorporated gospel call and response into his playing. Randolph was among the musicians to gain exposure outside of the church when the indie label Arhoolie discovered the “sacred steel” tradition and began releasing music by Eason and his disciples in the late 90s. The Campbell Brothers of Rochester, New York, have until recently gotten the most attention of the bunch, sparingly touring secular venues like the Old Town School of Folk Music, where they performed in 1999, but Randolph is the first to turn the music into a vocation, and he’s done it in record time. He began playing outside the church just last year, but his ecstatic, expansive blues-gospel style quickly attracted some of the leading lights of the jam-band scene, including the North Mississippi Allstars and John Medeski, with whom he collaborated on the recently released The Word (Ropeadope). That disc will certainly expand his audience, but I prefer Live at the Wetlands, the self-released debut by Randolph’s own Family Band–with cousins Danyell Morgan on bass and Marcus Randolph on drums and organist John Ginty, who’s not a relative, on Hammond B-3. Despite moments of hammy heavy-handedness, Randolph’s vocalic improvisations glide over their galloping deep-blues grooves with disarming ease. Tuesday, November 20, 10 PM, Back Porch Stage, House of Blues, 329 N. Dearborn; 312-923-2000 or 312-527-2583.