It depends on how loose your definition is, but aren't all records concept records? Stylistically, lyrically, chronologically, whatever, they all feature concepts.

Utter the phrase "concept album" and visions of rockers who've indulged themselves with albums and shows featuring protracted themes - David Bowie, Rush, The Who, Genesis, Pink Floyd, Alan Parsons Project - immediately come to mind.

Yet in the face of this quasi-narcissism, a new generation of bands now emerges with grandiose, epic affairs spanning multiple releases that have time and theory components adding strength and impact to the lyrics and music. Some of these musicians are coming from the unlikeliest of places, like Southern California hardcore rockers Thrice. Thrice is known for an intense energy channeled through heavy riffing, accelerated speed, and that post-emo vocal approach that is recreating how we find and hear melodies.

And now in spite of establishing itself as a heavy hitter in the field, Thrice has up and cut a concept album. "The Alchemy Index" is a four-EP release based on the elements. Volumes I and II, "Fire" and "Water" (released in October), and volumes III and IV, "Earth" and "Air" (to be released this spring), interpret the elements metaphorically and sonically in an adventurous departure from Thrice's sound.

But it isn't that far out for singer/guitarist Dustin Kensrue. "I think it's a natural progression in the sense that it's just the next record," Kensrue says from a tour stop in Philadelphia. "There's a conceptual element that guided us differently than if we just made our next record. Other than that, all I can say is it's where we wanted to go."

A concept record by definition typically limits the band to that concept. Thrice managed to work well within the boundaries.

"We were wary of doing a concept record, but we were intrigued by this idea," he says. "We wanted to do a four-disc set based on the four classic elements. We'd always tried to combine different kinds of music, different feels into songs. We were all interested in so many different kinds of music. Especially at this point we were trying to take our music to a place that was closer to some of our influences that were current rather than things we came from. This just seemed like a cool way to explore some new ground."

But a lot of Thrice fans stood on the old ground. Were they up for this adventure as well?

"We really don't care what people want us to play," Kensrue says. "Like with any kind of art form you need to be doing what you want to be doing, not what you think people want from you. Then you're just selling a product and that's not what it's about."

The "Water" disc is an ethereal dreamscape full of textures and mellower tones. Some Thrice fans are still hungry for the heavy.

"There's always going to be people who are continually disappointed," he says. "I think when people say they want something heavy they really just want it fast. Just because we're not screaming the whole time, or it's not a really quick speed, or there's no fast riffing, it's still heavy."

"The Alchemy Index" is heavy. It's intense. It's cerebral. It's an adventure. The lyrics aren't couched in as much metaphor as you might expect, addressing either reckoning or redemption as they do in the song "Firebreather" on the "Fire" EP. Judgement and deliverance are explored on the "Water" EP. The tune "Lost Continent" offers this lament:

"Was there a time we weren't at war/

When we knew what our hearts and hands were for/

I don't believe there ever was/

It's always been a lie/

A soothing lullaby/

We'll soon be swallowed by the sea"

The element theme that runs the course of the four EPs will have to be taken out of context live, as the band simply doesn't have time to perform the entire live rock opus. Some of the instrumental departures might be tough, too.

"We've never played the whole four records live," say Kensrue. "We have a lot of back catalogue now and you have to balance all that. About a third of the new set is new songs right now. It's actually working well. The ‘Water' stuff, we didn't know how it was going to work and we spent a lot of time before this tour figuring it out. It's not really guitar driven. It's not a normal rock band kinda thing. We shuffled things around, just taking each song and seeing how we can best keep the feel of the record but not limit it."

Kensrue doesn't completely shoot down the prospect of another concept record in the future, but you get the impression that for its next trip to the studio, Thrice may want to return to the heavier stuff it's known for. In the meantime, the powerful body of work created since the band hit the scene in 2001 may have built a strong enough fan base to withstand, except, and roll with the changes brought on by "The Alchemy Index." Who knows? Fans really listening and giving something new a chance - now that's a concept.

Thrice

Gordon Field House, RIT

Friday, December 14

7 p.m. | $21.50 | 232-1900, ticketmaster.com