"St. Anger" marked another large change in the band's sound. Guitar solos were excluded from the album, leaving a "raw and unpolished sound". The band used drop C tuning; Ulrich's snare drum received particular criticism. "New York Magazine"s Ethan Brown said it "reverberates with a thwong". The album's lyrics deal with Hetfield's drug rehabilitation and include references to the devil, anti-drug themes, claustrophobia, impending doom, and religious hypocrisy. At the advice of producer Rick Rubin, for its ninth studio album "Death Magnetic", the band returned to standard tuning and guitar solos. As a return to Metallica's thrash roots, "Death Magnetic" was a riff-oriented album featuring intense guitar solos and subtle lyrics dealing with suicide and redemption.