When you think of the type of music that gets played on the radio, the thought is usually accompanied by images of super-glossed arena rock stars, Hummer-driving rappers who survive gang shootings, or at least cleavage-popping, ubiquitous actress-turned-pop-stars. After all, Clear Channel, the ultimate evil media conglomerate, owns an ultimately evil amount of the nation’s radio stations — which means there’s a singular radio mainstream grievously controlled by The Man.

Luckily there’s a glaring exception: KCRW, a commercial-free public radio station out of Santa Monica, Calif., has an award-winning reputation for espousing an experimental but impeccable fusion of diverse genres. Most importantly, popularity and money aren’t the only things that concern them. Their new compilation album, the third in the “Sounds Eclectic” series, collects live performances from their signature show, “Morning Becomes Eclectic.” It is a phenomenal, quintessential mix tape — organic, intimate and pure. As its name implies, all the artists who appear on the disc are varied, but all are talented and true.

“Eclectic” is hosted by the wonderful and British-accented Nic Harcourt, who says he listens to 400 CDs a week. His efforts pay off: The CD has a euphonious multiplicity, boasting artists from the worlds of psychedelic rock (the Flaming Lips, the Polyphonic Spree), alt-country (Steve Earle, Iron & Wine) and folk (Damien Rice). But the best of all are the heavyweight imports: Radiohead and Franz Ferdinand.

While the likes of Ferdinand or Sarah McLachlan can be heard on most generic radio stations, you’d be hard-pressed to find Kinky (a Mexican electronica act) or My Morning Jacket (Kentucky indie-rockers) blaring on their very own radio showcases.

But that’s not to say “Sounds Eclectic” revels in obscurity. Its track list is instantly exciting for almost anyone with a musical consciousness: All of the songs are previously unreleased recordings from show performances, and KCRW attests that none were re-recorded, remixed or overdubbed (explaining the lamentable absence of Ashlee Simpson).

This rawness is none too obvious in Radiohead’s fantastic acoustic performance of “Go To Sleep,” a track from their underrated 2003 release, “Hail to the Thief.” In truth, the track is neither really Radiohead nor truly acoustic: The track only features lead singer Thom Yorke (who violently strums an acoustic guitar) and Jonny Greenwood on an undistorted but piercing electric. Yorke’s emotional vocals and the trotting beat of the darkly sober guitars mirror the complicated richness of the full band.

Damien Rice’s “The Blower’s Daughter,” so recently ingrained into popular awareness by its appearance in Mike Nichols’ “Closer,” has the same wonderful naturalness and quiet inwardness. Rice is sincerely soulful, uttering the repetitious chorus with increasing volume as the song builds and ebbs.

Iron & Wine’s Sam Beam may be one of the best living songwriters, but he scores here with a blissful cover of the Flaming Lips’ “Waitin’ For A Superman” (remember the “Garden State” soundtrack?). The track is a soothingly reflective ride around sweetly resonant acoustic guitar arpeggios. In comparison, Sarah McLachlan’s typically piano-driven “Answer” is merely a pleasant display of breathy femininity. But it lacks the discernible live quality of “Superman,” let alone its perfect lethargy.

The Polyphonic Spree’s “It’s the Sun,” with its psychedelic gospel-revival joy, starts off the compilation with uncontained jubilance. The slightly cultish group (25 members and counting) play with an ecstatic fierceness, best captured by a seamless transition in and out of its chorus. The album is not lacking in more upbeat tracks, especially evident in Franz Ferdinand’s definitely live “Take Me Out,” a song that knows a thing or two about transitions. Here the interesting imperfections of live music are consolidated with the tangible excitement of live performance. While the song’s characteristically glorious instrumental buildup isn’t as flawless as the produced version and the vocals have a more-homegrown roughness, the song retains its wondrous manic energy. More than the studio cut, the band’s cutting rhythm guitar is astonishingly articulated.

With its anthemic verses, crashing cymbals and skillful solo guitar riffs, My Morning Jacket’s “One Big Holiday” also brings epic, keyed-up energy to the disc. MMJ is reminiscent of big ’70s prog-rock, though their Southern roots are unmistakable, especially when you hear them live.

Even the tracks that don’t deviate much from their original form are great inclusions. Interpol’s “Untitled,” the first track from 2002’s darkly majestic “Turn On Your Bright Lights” is a great example of the New York band’s perfunctory talent for powerful composition.

The most out-there song on the album is Kinky’s very danceable “Mirando De Lado,” with a funk guitar and samba-like beat interspersed with a chorus of bubbly Spanish.

With “Mirando” as the only track that sounds radically different from most of the other songs, “Sounds Eclectic 3” could do to be more freewheeling (though it’s hard to complain). The artists won’t come as a shocker to anyone versed in the wide world of indie-rock (most of the names and sounds should be recognizable to most college kids).

But these performances were recorded two and in some cases even three years ago, before Franz Ferdinand had the best single of 2004, before Damien Rice’s voice was the romantic backdrop to “Closer” and even before Interpol was heralded as the savior of rock. The mix could be an album that perfectly sums up the best of 2004, which says a lot about Nic Harcourt, “Morning Becomes Eclectic” and KCRW.