Calling their new album Sé (pronounced Shay) — Gaelic for Six — may initially sound like a modest gesture from the maverick Irish instrumental outfit Lúnasa. “It’s true that we’ve been fond of direct, one-word titles in the past,” offers flautist Kevin Crawford. “And we did put it to a vote on our website — the fans had their part in it.” But there is something behind the title — an acknowledgement of progress, along with an acknowledgement of all the pressures and rewards born of the band’s willingness to explore new ground and constantly challenge themselves. Over the course of the five previous albums, Lúnasa have consistently taken traditional elements of acoustic Irish music and deconstructed them, welding those elements to bold new rhythmic frameworks that elevate the band’s virtuosity and create a thrilling new fusion all their own. Giving their sixth album a sparse, numeric title is Lúnasa’s way of accepting the challenge before them: they know that they are no longer the hot new band on the block — they are established as innovators, and are unafraid to take chances and continue to expand their music.

“We achieved what we wanted with The Kinnity Sessions,” Crawford says of the band’s much-lauded 2004 release and nomination for BBC Radio’s Folk Album of the Year, which captured the driving fury of their concerts with a punchy, live-in-the-studio recording process. “We were looking to create a more produced, studio-oriented album this time around.” The band’s lineup — Sean Smyth (fiddles, whistles), Crawford (flutes, whistles), Cillian Vallely (Uilleann pipes, whistles), and Trevor Hutchinson (double bass) — is capable of a wide range of textural variations, whether breaking off into intriguing sub-groups or in dizzying full-band counterpoint. Sé takes advantage of the Lúnasa’s resourceful musicianship, and also brilliantly uses a seismic shift in the band’s development as an opportunity to expand their sound.

“Donogh Hennesy bowed out last year,” Crawford explains, referring to the band’s founding guitarist. Hennessy’s precise fretwork was ingrained into the blueprint of their sound since the inception of Lúnasa. Rather than run out and find a Donogh clone, the band enlisted two musicians to fill the guitar role. Each contributes to Sé, individually on some tracks, and together on others. Tim Edey provides shimmering nylon-string accompaniment, whereas Paul Meehan adds steel-string. “Before it would have been Donogh layering things,” says Crawford. Now it’s two minds, interacting and contributing their own concepts and reactions. The result is a wider array of colors, and intriguing new variations on the band’s rhythmic core. Also notable on Sé is the haunting electric guitar of Conor Brady, particularly his electric slide guitar (another new color for Lúnasa) on “Boy in the Boat.” On the stately “Midnight in Avilés,” another guest, Karl Ronan, provides an elegant overdubbed trombone choir.

The new avenues opened up by Sé are seamlessly grafted onto Lúnasa’s instantly identifiable foundation, thanks to careful tune-selection and the production of bassist Trevor Hutchinson. “When it comes to finding material, Cillian and I start the process,” Crawford says. “We dig through hundreds of CDs, LPs, mini-discs, etcetera. We’re looking for something that’s unusual. Something that might suit the band, and hasn’t been widely recorded in the past.” For Sé, Vallely and Crawford started with over 200 tunes. They learned them inside and out, experimenting with different keys, rhythms, and meters. They then presented the songs to Trevor, Sean and the guitarists, working out how the accompaniment could strengthen and amplify the initial qualities that first drew them to the material. The individual songs are fashioned into sets (medleys), which spiral upward in intensity — often incorporating a number of different grooves within one set. One of Lúnasa’s trademarks remains their unique ability to modulate from one rhythm to another, while making the transition seem like the next logical step in a set’s unfolding drama.

Making a new album, Crawford concludes, is a challenge on more levels than is first apparent. “It’s not really easier for us!” he says with equal parts exhaustion and awe. “It gets tougher with each album — because you are constantly trying to make it sound fresh, but still sound like Lúnasa.” Fortunately, from day one Lúnasa has had a refreshingly edgy sound all their own — one that incorporates the haunting modality of traditional Irish music with a jazz-like fluidity and the unrelenting drive of the most well-oiled bluegrass bands. Sé is the hard-won, hand-hewn next step in Lúnasa’s unending evolution.