Dave Grohl's directorial debut is two-thirds history, one-third vanity project. It starts as an adoring portrait of a shabby-looking, analog-based Van Nuys studio that, against the odds, outshone nearly all of the fancily equipped rooms in the LA area. A ton of albums were recorded there, including Nirvana's Nevermind. With testimonials from musicians, producers, and Sound City employees, Grohl tracks the studio's '70s heyday and its '80s decline. Then the documentary shifts into "Dave Grohl musical fantasy camp" mode, as he buys Sound City's board and invites SC alumni to record new material, creating middling songs in real time. (DAVE SEGAL)