Most bands are easy to categorize. What you see or hear is what you get. In other words, listen to a couple of songs and you pretty much know what everything else is gonna sound like. Then there's System of a Down.

The group's self-titled 1998 debut was a striking, startling combination of speed-metal licks, quirky percussive vocals and powerhouse drumming juxtaposed against Mediterranean melodies, alt-rock flavors and textural rhythms. Their upcoming Toxicity, due September 4, is even more schizophrenic.

"I like to think we're like a cross between Pink Floyd and Slayer," bassist Shavo Odadjian said. "If you listen to the radio right now you'll hear a bunch of bands that sound like clones of each other. We want to sound like a band you can't clone or even categorize. We like to throw everyone off."

Not only does Toxicity sound different than everything else, from track to track System of a Down hardly even sound like the same band. One moment they're blazing away like Pantera fueled by the Dead Kennedys, and the next they're riffing like Iron Maiden alongside a 16-piece orchestra. Then out of the blue they'll bust into a tuneful ethnic passage.

Lyrically, the band is similarly all over the map. On "Prison Song" vocalist Serj Tankian rants about mandatory prison sentencing and how U.S. jails are overcrowded with petty offenders. In "Bounce" he moans about the ecstasy of group sex, and for "Arto" the band plays a somber Armenian prayer song for the dead.

"There's no guitars or anything on that one," Odadjian said. "We used these Armenian instruments and we all chanted. It's really emotional, and my mom cries every time she hears it. I wanted to remember all the Armenians that died in 1915 during the genocide."

The Armenian genocide, in which an estimated 1.5 million died, began during World War I and involved the Turkish military deporting, torturing and killing Armenians in the Ottoman Empire.

In addition to "Arto," Toxicity is graced with other cultural touches, courtesy of the four bandmembers' Armenian upbringings. However, the band takes umbrage to being described as an Armenian metal band.

"There are a lot of elements of Armenian [culture] in our music, but it's not the basis of our band," a slightly annoyed Odadjian said. "We happen to be four Armenian guys who share the same culture, but we never set out to be an Armenian band. If there were four Mexicans, you wouldn't call it a Mexican rock band. And if it was four Jews you wouldn't call it Jew-metal."

While not a concept album, Toxicity was conceived as a unified piece of work.

"When I listen to a band like Pink Floyd, I don't know the names of the individual songs, I know the full albums," Odadjian said. "That's what we want for our albums. We don't want to name our songs after the choruses, so we sometimes come up with random titles. We don't care if people don't know the names of the songs, we want them to play it and never get sick of it. We want it to be exciting, melodic, heavy and emotional. It can make you cry and laugh and be angry."

The first single from Toxicity is "Chop Suey," which starts with a guitar strum and a tribal beat and segues to a serrated stop-start punk verse before drifting into an ethereal chorus colored by a bouzouki, a Greek stringed instrument.

"The song is named 'Chop Suey' because that's really what we are musically," Odadjian said. "To me it's about drug addiction, but we've taken something really serious and made it a little quacky."

A few weeks ago, System of a Down shot a video for the song in Hollywood with director Marcos Siega (Blink-182, Papa Roach). Before the shoot, the band posted a note on its Web site, inviting fans to take part.

"We thought we'd get about 500 kids, because we didn't announce it on the radio," Odadjian said. "Instead, we got about 1,500. There was a fire marshal there, and he wouldn't let them all in, so we had to rotate them 800 at a time."

The video, shot in the parking lot of a sleazy pay-by-the-hour hotel, is a concert clip that captures System of a Down's frenetic live performance. For the shoot, the band erected a makeshift stage and invited fans to swarm around them like bees to a hive.

"We did it about two blocks from where I grew up," Odadjian said. "Everyone views Hollywood as a glamorous place with palm trees and movie stars, but when we were growing up all we saw were poverty, hookers and bad stuff. It's an evil town — a toxic city, which is how we got the name of our record."