Los Super Seven isn’t a band, per se — it’s a collective, organized by manager Dan Goodman, who comes up with a concept for each of the group’s albums and assembles a band to fit. For their third album, Goodman turned to music journalist/record producer Rick Clark, whose giveaway CDs for the Oxford American journal are highly regarded in certain quarters. Inspired by ZZ Top’s classic boogie rock tribute to border radio, “Heard It on the X,” Clark came up with a sharp idea: a salute to the heyday of AM radio on the Texas/Mexico border, when rock & roll, blues, country, jazz, Western swing, and mariachi mixed freely. Clark and Goodman drew up a list of songs and musicians to play them, recruited two different core bands — indie rockers Calexico and a group featuring Charlie Sexton, who also served as the third producer on this album (along with Clark and Goodman), with drummer Hunt Sales — and then brought in a bunch of Texas-identified singers. Some — like Raul Malo, Joe Ely, Rick Trevino, Ruben Ramos, and Freddy Fender — were Los Super Seven veterans, while others — John Hiatt, Lyle Lovett, Rodney Crowell, and Clarence “Gatemouth” Brown — are new to the game. That list of musicians signals that Heard It on the X is not nearly as Latin-centric as its predecessor, Canto, which theoretically means it may play to a wider audience, but in 2005, with all this roots music and versions of songs that are 30-40 years old, it’s unlikely that this will get much play outside of roots fanatics and those who long for the heyday of Musician magazine. That said, Heard It on the X is executed about as well as it could be. The song selection is expert, touching on lesser-known tunes by such Texas giants as Doug Sahm and Buddy Holly and standards by Blind Lemon Jefferson, ZZ Top, and Bob Wills, adding a few cult favorites and a new tune or two along the way. While this certainly reads like an eclectic listen on paper, in practice it flows easily, thanks to both the house bands, the professional (albeit a bit too clean) production, and the fact that the borders separating these genres are virtually nonexistent these days. There’s no real cross-pollination within the grooves themselves (having Ramos sing the title track doesn’t quite qualify, since it still comes across as bloozy boogie rock), the styles merely rub shoulders with each other, and since all the musicians already travel in these circles, there are no real surprises (well, apart from Hiatt’s mannered vocal on “I’m Not That Kat (Anymore),” but on second thought, that’s not much of a surprise, either). But surprises are overrated, particularly with so many similar albums shooting too high and missing the mark. Here, the songs are excellent, performed by the right musicians, and the result is a highly enjoyable record for anybody into any of the featured artists or songwriters. If this doesn’t pack the thrill or sense of discovery that the original recordings have, mark that down to the ultimate triumph of border radio — its influence has been so strong and so far-reaching that listeners take its innovations for granted, so an album as nonchalantly diverse as this seems like a welcome everyday occurrence.