“Old System” is a phrase that will be thrown around when people talk about Mezmerize.

It’s not a negative criticism, but fans of System of a Down will definitely notice a vast difference from the band’s previous three albums.

Mezmerize, the spring release from the band’s spring/fall double-disc Mezmerize/Hypnotize, carries all the familiar elements of a System album, but a distinct line can be drawn between the band’s debut effort and its fourth.

The disc kicks off with “Soldier Side,” a slow-electro-acoustic intro that introduces a new dynamic in System of a Down – dual vocalists. Almost every song, excluding “This Cocaine Makes Me Feel Like I’m On This Song,” features frontman Serj Tankian sharing vox duties with guitarist/songwriter Daron Malakian.

Lyrically, the album runs the spectrum from silly to political. Tankian talks about “choking chicks and sodomy” on “Violent Pornography” but also criticizes the government for “feed[ing] us lies from the tablecloth” on “B.Y.O.B.” (Bring Your Own Bombs).

System has traded in their well-known Middle Eastern sound for something less ethnic and more thrash-metal freak-out. Lurching riffs accompany pounding drum fills that carry the disc’s 11 tracks on a set selection that’s soaked in Hollywood references and strangely, lyrics about Tony Danza.

The album feels incomplete, probably because it’s only one-half of a massive effort, as the band and producer Rick Rubin chose songs that vary the CD extensively, however the mix lacks the usual power the band has shown in previous releases.

The shining star of Mezmerize is “Question!” which displays the heavy and softer sides of System in a perfectly balanced three-minute track.

Fans will feel a bit torn when listening to this scattered disc as no song compares with “Sugar” or “Toxicity,” but maybe things will make more sense when Hypnotize drops in the fall.