The venerable Chieftains have been at it for so long, it’s easy to forget that they were once considered revolutionary. The group formed in 1962, creating a new paradigm for Irish traditional music: an instrumental ensemble that had no vocalist. The members’ affable nature somewhat belies their serious talent, but they have continued to gently push boundaries instead of rest on their laurels. Last year, the group was hit with the loss of its long-time member, harpist Derek Bell. After months of playing onstage with one empty seat, the group performed a tribute concert in Dublin, inviting some old mates and newer friends who have become part of the band’s extended family. The Chieftains have a go at some trad Irish tunes, but also revisit their late-career ventures to Galicia, Spain, with Carlos Nunez, and to American country with singer Alison Moorer. The resulting CD has a few poignant moments, but overall it seemed like the group decided to honor its absent bandmate with celebratory tunes and touches of good humor, sharing the music that they created together over 30 years.