Whether you're a Hüsker Dü fan, a Sugar fan, or a solo Bob Mould fan, you should show up enthusiastically for this Friday's performance, since it will focus on Sugar's Copper Blue album — one of the greatest and most important indie records of the 1990s (and that's saying something, given the caliber of alt music from that decade). Mould will play material from his excellent new solo album, Silver Age, too — a project he recently referred to as "simple pop," but which holds its own against the distortion-soaked noise pop that made the current S.F. resident indie-famous. Frankly, we'll be showing up simply for nostalgia-ridden live renditions of "Helpless" and "If I Can't Change Your Mind." You should, too.