The Mars Volta really can’t be compared with anyone else.

Look around. I dare you. Try to find another band like this one, a band for which labels like “prog,” “punk,” “metal,” “salsa” and “jazz” have all been tried, even in combination, and then discarded because even the five-part adjective doesn’t do the music justice. The Mars Volta is perhaps the oddest, most ambitious, most all-encompassing group of musicians whose work is available in your local Sam Goody. That’s what’s most frustrating about trying to describe their work – there’s no really good reference point. They are strange and singular.

But what sometimes gets lost amidst talk of their willfully obscure concepts and big hair is that the Mars Volta boys are outstanding players. I first encountered Cedric Bixler Zavala and Omar Rodriguez-Lopez (they even have prog-rock names) as members of At the Drive-In, a powerhouse punk band. I came in where most people did – with their swan song, Relationship of Command, and I owe my friend Allison Hart a huge thanks for making me listen to it. RoC is one of the most inventive, jabbing modern rock records you can buy, even though it never breaks free of the punk template for very long.

What I didn’t realize when I heard Relationship was that At the Drive-In was splitting at the seams when they recorded it. The push and pull of aggression and artistry evident on that record can be traced to the snarling, slapping fight between its members, drawn cleanly along party lines. When the inevitable breakup occurred, three-fifths of AtDI formed Sparta, essentially a less ambitious clone of their previous band. They went on to write earthbound radio-rock with a few added textures, but nothing that would set them apart from hundreds of other bands.

Meanwhile, Zavala and Rodriguez-Lopez created the Mars Volta, and acted as if they had excised the Spartans like a cancer. Call their music what you will, but it’s certainly not earthbound. Their debut full-length De-Loused in the Comatorium is a huge rush of ideas, a teetering structure that endlessly rebuilds itself. Extended running times, songs with titles like “Cicatriz Esp” and “Eriatarka” – well, you can see where the prog label might come from. I’m surprised that the band didn’t object to being lumped in with all the swords-and-sorcery noodling that makes up much current prog, though, because their work is explosive, melodic, and nearly noodle-free.

It’s become clear what an influence the five At the Drive-In guys had on each other now that that influence is gone. Sparta’s second album, Porcelain, was even more accessible than their first, with calming string sections on a few tracks and very simple structures on most. The Voltas, on the other hand, have just released Frances the Mute, their five-song, 77-minute sophomore effort, and it’s even more insanely ambitious than the first. This is not for the musically faint of heart.

There’s never been a question of what the Mars Volta is capable of playing, only of what they choose to play, which is among the most freeing of dilemmas. On Frances, they’ve chosen to keep the progressive and punk elements of their style and mix in healthy doses of Santana (really) and Zappa, with a little Merzbow noise sculpting to boot. The album is a single piece from beginning to end, with no breaks between tracks. The three minutes of doom-pop that make up the first half of “The Widow” are the only three minutes of accessibility here, the only window in for the casual listener. For everything else, you’d better bring a comfortable chair and an open mind.

Frances starts with about a minute of tenderly plucked acoustics and Zavala’s clear, high voice. The melody, called “Sarcophagi,” is the first movement of the 12-minute “Cygnus…Vismund Cygnus,” and it crashes in with full force in abrupt, energizing fashion. Zavala is on fire here, draping the song with his awe-inspiring harmonies, and the stop-time rhythms are arresting.

“Cygnus” also, by its conclusion, sums up what’s wrong with this album. After nine energetic, constantly shifting minutes, it descends into an overly long coda made up of electronic noise and tape manipulation. This, and the extended guitar solo, spotlight the unfortunate sides of their Zappa influence. The end of “Cygnus” would be more palatable on first listen if “The Widow” didn’t do the same thing – it’s a three-minute song saddled with nearly that length again in noisy, spliced nonsense.

But that’s all part of the record’s attitude – this is an album on which every song is defiantly too long. The first four songs could each have been three to five minutes, but what would have been challenging and controversial about that? Instead they’ve embraced the everything-can-be-music aesthetic, and opened their record up into a huge, expansive head trip. Cedric and Omar know what they’re doing, and by the fourth track, “Miranda That Ghost Just Isn’t Holy Anymore,” they’ve integrated their static-filled interludes into the rising dynamic of the song. You’re more than four minutes into “Miranda” before a single note is played, but the resulting crescendo is pretty astonishing.

The Santana vibe plays out most strongly on “L’Via L’Viaquez,” another 12-minute monster sung almost entirely in Spanish. The Latin rock groove that bursts in after about 40 seconds of fluttery noise is perhaps this album’s biggest surprise, reveling in its own Ricky Martin-ness. The groove breaks down into a slow salsa numerous times, and Rodriguez-Lopez uses backwards guitar and textures to creepify what’s probably the most un-creepy beat pattern in music history. As “L’Via” continues, the guitars get more dissonant and the drums more eruptive, and it turns into spacey Spanish punk. It’s a fluid mix of genres that stands out as the high point of the record’s first half.

The aforementioned “Miranda” is next, and this one both suffers and benefits the most from the decompressed nature of this album. It runs 13 minutes, and contains two verses and three choruses, barely enough to float a song one-third its size. But damn if it doesn’t work, the intense slow build of the guitars and horns carrying you through. Unfortunately, it climaxes at the nine-minute mark and peters out by the 10, and you’re left with another overly long coda to remind you of just how slight “Miranda” actually is. The horns and strings that play the song out are marvelous, though.

So, four songs in 45 minutes, and then we’re left with “Cassandra Gemini.” Honestly, I didn’t know what to expect from a 32-minute Mars Volta song, but I sure wasn’t anticipating the sustained live band explosion that is “Cassandra.” After the sedate waves of “Miranda,” this song just blows up, its brief intro coalescing into a flutter of flutes and horns dotting an extraordinary landscape of drums and guitars. The most amazing thing about “Cassandra” is that it continues in basically the same vein for more than half an hour, and it’s the only song here that doesn’t sound overextended.

This song is the most Zappa-esque, descending into free jazz at times and letting Adrian Terrazas really let loose on saxophone, a la Ian Underwood. “Cassandra” is the song that fully cements Omar Rodriguez-Lopez’s status as a guitar god – he’s simply relentless, offering friction where it’s needed and bliss where you wouldn’t expect it. What sounds like a jam on first listen takes shape as a fully realized composition on repeated dives through, especially when the horn section comes in on the third movement. Zavala holds the whole thing together with his astounding vocals, soaring and spitting at once.

And with astonishing grace, they close “Cassandra” with its chorus (absent from the song for about 25 minutes at this point) and a reprise of “Sarcophagi,” uniting the record. Or, at least, trying to. Ordinarily one would look to the lyrics for common threads between five songs this diverse, but I can’t make head nor tail of them. The album is supposedly about a diary found by deceased band member Jeremy Ward, and the horrors contained within, but I’ve stared at the lyric sheet for a couple of days, and I’ve got nothing. Frances is an album that will stand or fall on its musical merits alone.

And for about an hour of its 77 minutes, it stands pretty well. It’s worth hearing just for a freak-out like “Cassandra Gemini,” the likes of which I haven’t encountered on a major label album in years. The rest of the record, unfortunately, drowns some great concepts and melodies in a sea of wasted time. Nothing here is as willfully obnoxious as Wilco’s “Less Than You Think,” but I do wish that some of the obvious care lavished on the sonics and the noise was spent on writing two or three more fantastic songs.

But then this wouldn’t be as confounding a record as it is, and I confess to admiring some of the sprawl on those terms. Zavala and Rodriguez-Lopez obviously wanted to make exactly this record, exactly this way, and it’s heartening that they were able to, even if the results are less than they could have been. As I said, there is no question of what the Mars Volta can play, only of what they choose to play, and even with their drawbacks, I would still take Frances the Mute and De-Loused over anything these guys (and their former bandmates) have done. True artistic ambition is in short supply, and if nothing else, the Mars Volta should be commended for following their vision without compromise.

See you in line Tuesday morning.