Uncle Earl's upcoming release Waterloo Tennessee may be both a blessing and a curse for the bluegrass quartet.

That's because legendary and obscenely underrated Led Zeppelin alum John Paul Jones produced the new album. Jones' musicianship and production skills have given him iconic status among many and could cast a looming shadow over the work of Uncle Earl. Or it could bring new ears to new music, which is just what a band like Uncle Earl could use after their critically acclaimed 2005 album, She Waits for Night, had relatively slow sales.

Bluegrass music had lost much of its momentum prior to the start of the 21st century, until the release of the wildly successful 2000 film "O Brother Where Art Thou," which carried on its coattails a fantastic bluegrass and blues-laden soundtrack, giving the genre the kick it needed. Soundtrack artists such as Alison Krauss and Union Station finally became household names, even though Krauss had been a staple of the music scene for years — 20 Grammys to be exact. Newer bands emerged from this resurgence as well, such as the highly praised The Avett Brothers, who have been making a niche for themselves with their frantic brand of bluegrass.

The four women of Uncle Earl may have found something to get their music more widely heard with their new producer, who stumbled across them at a bluegrass festival in 2004. Though their music has always been solid, Jones' name will only help in earning the credit the group deserves.

Under the scrutiny of this newfound attention, Waterloo Tennessee does not disappoint. By drawing on traditional sounds, classical melodies, modern structures and the vast talent of each member, Uncle Earl has created a strong album rich in both tradition and experimentation.

Although the members share vocal duties, the album is strikingly cohesive. Each voice is subtly different but fits together so well with the others that it's hard to imagine it in any other company. To continue the comparison, the vocals can't quite match the angelic softness of Alison Krauss, but the vocal maturation of each of the members from She Waits For Night to Waterloo Tennessee should have the aforementioned blonde songstress looking over her shoulder.

A cappella tracks such as "Buonaparte," which acts as a short introduction for the aptly placed rendition of "Bony on the Isle of St. Helena" and "Easy in the Early ('Til Sundown)," exhibit the commanding vocal harmonies the four are capable of, enticing listeners to sit back and let the songs envelope them.

For those asking the question "This is bluegrass, where is the fiddle?" have no fear — the fiddle is there and is one of the album's strongest points. Rayna Gellert plays her fiddle so well on the new album, in fact, you may wonder if she is in cahoots with Charlie Daniels down in Georgia, beating the devil for a fiddle of gold.

What makes Gellert's playing so admirable on Waterloo Tennessee is her sense of restraint. Her ability to carry a song with her high-energy fiddle wailings is evident: Gellert's playing drives several songs, such as the cover of the little-known Bob Dylan tune "Wallflower" and the original composition "Drinker Born." What is more impressive is her ability to take a back seat when the song calls for it in order to put down a low, rolling rhythmic backbone.

Sounds like the subdued and melancholy drones in the album closing "I May Never" provide such a strong contrast to the more upbeat songs that they leave a much stronger imprint on the listener. Though these soft passages may go unnoticed, the lament would fall flat without them.

But it's not all tears and sorrow — good bluegrass has to be fun and uplifting as well. Uncle Earl satisfies these demands with the eclectic sonic blends of their more experimental songs. The best of these, "Streak o' Lean, Streak o' Fat," is sung completely in Chinese and pays homage to, of all things, Mao Zedong's favorite dish in his home province of Hunan.

Besides his production skills, Jones lends his musical chops to several songs. In typical fashion, the vastly versatile musician's contributions include parts on piano, mandolin, papoose and wobble board.

Even with such a legend at the helm, Waterloo Tennessee is really about the four talented women behind the instruments. By putting out another quality album to follow their 2005 effort, the four should again garner critical acclaim, but hopefully this time with well-deserved lifts in record sales. It's well within reach of the group, as long as the knowledge and clout of John Paul Jones turn out to be a blessing rather than a curse.

Uncle Earl will perform tonight with Jim Lauderdale at the High Noon Saloon. The show starts at 9:30 p.m. and tickets are $12 in advance, $15 at the door.

Grade: 4 of 5