When Coldplay sampled Kraftwerk on their third album, X&Y, it was a signifier for the British band, telegraphing their classicist good taste while signaling how they prefer the eternally hip to the truly adventurous; it was stylish window dressing for soft arena rock.

Hiring Brian Eno to produce the bulk of their fourth album, Viva la Vida, is another matter entirely.

Eno pushes them, not necessarily to experiment but rather to focus and refine, to not leave their comfort zone but to find some tremulous discomfort within it.

In his hands, this most staid of bands looks to shake things up, albeit politely, but such good manners are so inherent to Coldplay's DNA that they remain courteous even when they experiment.

With his big-budget production, Eno has a knack for amplifying an artist's personality, as he allows bands to be just as risky as they want to be -- which is quite a lot in the case of U2 and James and even Paul Simon, but not quite so much with Coldplay.

And yet this gentle encouragement -- he's almost a kindly uncle giving his nephews permission to rummage through his study -- pays great dividends for Coldplay, as it winds up changing the specifics without altering the core.

They wind up with the same self-styled grandiosity; they've just found a more interesting way to get to the same point.

Gone are Chris Martin's piano recitals and gone are the washes of meticulously majestic guitar, replaced by orchestrations of sound, sometimes literally consisting of strings but usually a tapestry of synthesizers, percussion, organs, electronics, and guitars that avoid playing riffs.

Gone too are simpering schoolboy ballads like "Fix You," and along with them the soaring melodies designed to fill arenas.

In fact, there are no insistent hooks to be found anywhere on Viva la Vida, and there are no clear singles in this collection of insinuatingly ingratiating songs.

This reliance on elliptical melodies isn't off-putting -- alienation is alien to Coldplay -- and this is where Eno's guidance pays off, as he helps sculpt Viva la Vida to work as a musical whole, where there are long stretches of instrumentals and where only "Strawberry Swing," with its light, gently infectious melody and insistent rhythmic pulse, breaks from the album's appealingly meditative murk.

Whatever iciness there is to the sound of Viva la Vida is warmed by Martin's voice, but the music is by design an heir to the earnest British art rock of '80s Peter Gabriel and U2 -- arty enough to convey sober intelligence without seeming snobby, the kind of album that deserves to take its title from Frida Kahlo and album art from Eugene Delacroix.

That Delacroix painting depicts the French Revolution, so it does fit that Martin tones down his relentless self-obsession -- the songs aren't heavy on lyrics and some are shockingly written in character -- which is a development as welcome as the expanded sonic palette.

Martin's refined writing topics may be outpaced by the band's guided adventure, but they're both indicative that Coldplay are desperate to not just strive for the title of great band -- a title they seem to believe that they're to the manor born -- but to actually burrow into the explorative work of creating music.

And so the greatest thing Coldplay may have learned from Eno is his work ethic, as they demonstrate a focused concentration throughout this tight album -- it's only 47 minutes yet covers more ground than X&Y and arguably A Rush of Blood to the Head -- that turns Viva la Vida into something quietly satisfying.