A year ago last night, Paul A. Caruso Jr. was on ''Late Night With Conan O'Brien," playing drums behind his friend and neighbor Joe Perry.
For many rock 'n' roll musicians who cut their teeth in the Boston club scene of the 1970s, the chance to perform with Aerosmith's lead guitarist on national television might be a suitable career finale. For Mr. Caruso, it was more of a grace note.
A gifted drummer who could play several instruments, Mr. Caruso could take the power of rock music and mold it into something prayerful and use his spiritual grounding to make his rock drumming more powerful. He was as comfortable playing in the front of a church as he was before cheering rock fans.
''He was able to balance these worlds," said Dan Burns, a longtime friend who attended Holy Family Church in Duxbury with Mr. Caruso.
''Paul was one of the very few people who was not swept up in the Aerosmith glamour, or the perceived glamour," Perry said yesterday. ''He was pretty matter of fact. He just loved to make music."
Mr. Caruso, who coproduced and played drums on ''Mercy," a Perry instrumental that was nominated for a Grammy Award, collapsed in his Kingston house Wednesday and died. He was 50. The family is awaiting results of tests to determine the cause of death.
''I'm in shock about it," said Perry, who had planned to work with Mr. Caruso in a studio on Monday. ''He was the engineer in my studio and worked with me on my whole solo record last year. I've known him for 18 years, ever since I moved to Duxbury. . . . His presence will be more than sorely missed in our neck of the woods. He was a good friend and a great musician."
Mr. Caruso grew up in East Boston and Revere, where he helped formed Sass, a power trio. In 1979 he went to meet with The Atlantics when the band was looking for a new drummer.
''He walked in, and he was very sharp," said Tom Hauck of Gloucester, who was a guitarist with the band. ''He had on a summer-weight sports jacket and sunglasses, and he looked like a million bucks. He started playing, and it was instant chemistry."
Valued for his musicianship and his ear for how a song should sound, Mr. Caruso helped shape ''Lonely Hearts," perhaps the band's best-known single.
''He had wonderful technical skill for a rock drummer," Hauck said. ''He had a light touch when he needed it, and he could play very loudly and very powerfully. He had a musicality about him that came through in his drumming. And he sang high harmonies for The Atlantics -- he had a beautiful voice."
Mr. Caruso also had a maturity that was rare in any rock music scene.
''He was a consummate diplomat," Hauck said. ''He really knew how to work with other people and make them feel at ease. He was the opposite of the quintessential rock star."
The Atlantics split up in 1983, and Mr. Caruso moved a couple of years later to Kingston, where he built Bay Farm Sound Studio as part of his house. He and his wife, Susan, had two sons and had been a couple for about 30 years, since they met at a fashion show.
''He was just very grounded here," she said. ''He loved his family and was just a great dad."
In his studio, Mr. Caruso worked with a variety of musicians, some well-known, others less so. He treated them all with respect and dignity, whether the musician was his neighbor Perry, part of the rock 'n' roll firmament, or a teenager he was encouraging to sing as part of the youth music program at St. Mary's Church in Hanover.
''He was a great perfectionist, but he would really bring the best out of everybody," Burns said. ''He had the ability to do that without being browbeating or overbearing. He would do it by encouraging. He would affirm you."
Mr. Caruso's musical association with Perry began after they became neighbors.
''One day he just went over, and they hit it off," his wife said.
The two were both adept at many instruments. When Perry released his eponymous album last year, he played all the instruments, except drums, which Mr. Caruso played.
The two also shared producing duties on the album. Among the tracks was ''Mercy," which was nominated for a Grammy as best rock instrumental performance, but did not win at the ceremony in February.
Mr. Caruso also was an engineer on two Aerosmith albums, ''Just Push Play" in 2001 and ''Honkin' on Bobo" in 2004.
''He was active in any engineering aspect in the last four to five years since we've been recording on the South Shore," Perry said.
Mr. Caruso was rare, Perry said, in that his experience bridged the time from when studios recorded on tape to the current era of digital sound and computers.
''And he was a slamming drummer," Perry said. ''He also had formal music training, which is rare in the rock 'n' roll world. He could sit down and play any kind of music, but he loved to rock."
Unlike many who long for the rock lifestyle of excess, though, Mr. Caruso was more at home at his home -- and at church.
''He had a very deep faith, which I think influenced his whole life," his wife said.
''His faith is so much a part of his life," said Burns, who lives in Duxbury. ''He had this incredible desire -- and we talked about it often -- to use his talents and gifts to feed the spiritual life."
In addition to his wife, Mr. Caruso leaves two sons, Christian and Zachary; his father, Paul Caruso Sr. of Winchester; and his mother, Claire Nye of Weymouth.
A funeral Mass will be said at 10 a.m. Tuesday at Holy Family Church in Duxbury.