Traditional Irish Music’s Envoys, the Chieftains, on Stage Tonight at Pacific

One way to keep a band together for a quarter of a century is to avoid too much togetherness.

Paddy Moloney, who has led the Chieftains through 25 years as the preeminent group in Irish traditional music, says that keeping a little distance has helped keep the band members close.

“We keep away from one another,” Moloney said over the phone this week in his good-natured Dublin brogue. “There’s a rule that when we book into a hotel, we don’t want to be next to each other. We want to be on different floors. On airplanes, we want the seating to be miles apart.”

That way, Moloney said, when the six Chieftains meet at a concert hall--tonight it will be the Pacific Amphitheatre in Costa Mesa--there’s a sense of freshness and happy reunion that can carry over into their music.

“Then it’s like we all never met. It’s a big party again.”

After 25 years, the Chieftains are still finding fresh, interesting things to do with a centuries-old style of music played on traditional instruments like uilleann pipes (a less wheezy cousin of the bagpipe), tin whistle, harp, fiddle and bodhran, the Irish drum. The Chieftains deploy this folk artillery in a wide-ranging repertoire that includes sentimental airs, stately marches, effervescent reels and jigs, and driving, tumbling pieces that bristle with pagan energy.

Far from coasting through their 25th anniversary year, the Chieftains are about to release one of their finest, most adventurous projects: “Irish Heartbeat,” a collaboration with Van Morrison.

It’s a match between a one-of-its-kind band that defines Irish music, and a singular vocalist who has been Ireland’s greatest contribution to the music of the rock era. The album, due in stores Monday, is a gorgeous, varied and soulful excursion into traditional Irish music.

Morrison’s unpredictable, improvisatory singing (he shows a particular fondness for guttural mimicry of the sound of Moloney’s pipes) meets the Chieftains’ honed precision on a selection of traditional songs and revised versions of two previously released Morrison originals, “Irish Heartbeat” and “Celtic Ray.” Morrison brings his personal brand of Celtic mysticism, but the Chieftains serve as an anchor on earthy songs of bounding, roustabout joy and on laments about homesickness and love lost (for sheer tears-in-a-beer-glass ruefulness, “Carrickfergus” equals any country-and-Western sob story that has ever come out of Nashville).

Morrison has a reputation as a reclusive, temperamental and musically exacting figure. As Moloney tells it, barriers came down during an extended feeling-out period that preceded any music making.

Morrison called “out of the blue” last June, saying he was interested in making an album with the Chieftains, Moloney said. “For about three months, we kept meeting and having little chats on the telephone at 1 or 2 o’ clock in the morning.” Morrison, based in London, visited Moloney for several days at his home overlooking an 8th Century monastery south of Dublin.

“Most of the time we didn’t talk about the album,” Moloney said. “We were both feeling our way with one another, but in the end, it all happened.” Morrison and the Chieftains toured England together last month and will play dates in Ireland in September, Moloney said. No collaborative shows have been planned for the United States yet, but Moloney said he is eager to do it.

Even without an American tour with Morrison, the Chieftains have plenty to keep them busy. They recently finished recording an album of their own, Moloney said, and they also supplied the music for an upcoming Windham Hill children’s album, “The Tailor of Gloucester,” with narration by Meryl Streep.

Before coming into such demand, the Chieftains spent their first 12 years as a band splitting time between music and day jobs. Moloney, the grandson of a flute-playing farmer, grew up in an atmosphere where “the source of entertainment was music and dance.” He absorbed traditional songs at community dances known as “Hoolies,” where “they’d start at eight o’clock, and go on till 8 the next morning.”

In 1963, the Chieftains formed and released their first album. While they made a name for themselves in folk music circles, they didn’t make a living as folk musicians. Moloney, one of three original members still with the band (the Chieftains have had only three personnel shifts in their history), worked as an accountant in the early days, then became head of a Dublin record company.

In 1975, the Chieftains’ traditional sound found a big following in England, and a sold-out show at the Albert Hall persuaded the band to jump into performing full time. In 1976, the Chieftains won further acclaim with their contribution to the Oscar-winning film score for “Barry Lyndon.”

The Chieftains tour about six months a year, and Moloney, who doubles as the group’s manager as well as its musical director (that accountancy background helps), can reel off prominent engagements that have been booked into next year.

“It’s not like rock ‘n’ roll. You don’t make a million dollars,” he said. “We make a good living at it, but it’s tough going. You have to be on the ball, on the go all the time.”

After 25 years, Moloney said, the Chieftains are far from exhausting the possibilities of the Irish musical tradition. “There’s so much. We often say, ‘God, we’ve never played that song on stage.’ There are hundreds of ideas in my head that I still want to get out.”

The show Saturday will include a bit of Chinese folk music, Moloney said, as well as a special Irish dance piece featuring a troupe led by Patricia Kennelly, a Los Angeles-based teacher of traditional Irish dance whom he met last year.

Moloney takes pleasure in the fact that the Chieftains’ silver anniversary coincides with the yearlong celebration of the 1,000th anniversary of Dublin’s founding, and with his own 50th birthday, which is coming up Aug. 1.

“I still feel I have another 25 years of playing to go on with,” he said.

The Chieftains and the Kennelly Irish Dancers will perform tonight at 7:30 at the Pacific Amphitheatre, 100 Fair Drive, Costa Mesa. Tickets: $19.25. Information: (714) 634-1300.