Joe Goldmark is part owner of Amoeba Music and founder of Escape from New York Pizza. But for fans of the twang, he's best known as the king of pedal steel. Goldmark has been playing this challenging instrument — a variation on the guitar involving complex string and pedal combinations — since the '60s. Together with his band, the Seducers, Goldmark holds down a free monthly residency at the Riptide (3639 Taraval at 47th Ave., 681-8433), setting up on the floor, right next to the bar. The group gives myriad genres (reggae, R&B, rock, and, of course, country) a dose of psychedelic twang on the second Sunday of every month, an excellent pick-me-up before you have to put the weekend down.