J. Geils, a guitarist who lent his name to the J. Geils Band, a popular rock group whose early 1980s hits included “Centerfold,” “Freeze-Frame” and “Love Stinks,” was found dead April 11 at his home in Groton, Mass. He was 71.

Groton police said officers responded to a well-being check at his house and found him unresponsive. He was pronounced dead at the scene. The cause was not immediately known.

Mr. Geils, whose first name was John, was an aficionado of early blues and jazz music and founded the J. Geils Blues Band as a Massachusetts college student in 1967. The group evolved from its origins — and dropped “blues” from its name — to become a high-powered rock band, anchored by charismatic lead singer Peter Wolf.

After releasing its first album in 1970, the band had several Top 40 singles, including “Looking for a Love,” “Give It to Me,” and “Must of Got Lost.” The group opened for the Rolling Stones and other top acts in the 1970s, and its 1973 album, “Bloodshot,” hit the Top 10.

With a sound that was a combination of arena rock and back-alley bar band, the J. Geils Band gained popular momentum with the 1978 album “Sanctuary,” and became renowned for presenting dynamic live performances.

J. Geils, guitarist and leader of the J. Geils Band, in 1973. (Fin Costello)

“It’s all about putting the right note at the right time at the right place,” Mr. Geils said in 2011, when asked to explain the secret of his music.

In addition to Wolf and Mr. Geils’s ringing electric guitar, the band featured Richard “Magic Dick” Salwitz on harmonica, Seth Justman on keyboards, Danny Klein on bass and Stephen Bladd on drums. Wolf and Justman wrote most of the group’s songs.

The band had a breakthrough with the 1980 album “Love Stinks.” The in-your-face title track — “I’ve had the blues, the reds and the pinks, one thing for sure, love stinks” — seemed to encapsulate the cynical side of rock-and-roll and was later recorded by Joan Jett.

In 1981, the Geils band found its greatest success with its 12th album, “Freeze-Frame,” which reached No. 1 on the Billboard album chart. The catchy title track climbed to No. 4, and another tune, “Centerfold,” was No. 1 song in the country for six weeks in 1981 and 1982.

The song, written by Justman, is about post-adolescent disillusion, as a young man realizes his boyhood crush has bared it all:

Years go by I’m lookin’ through a girly magazine

J. Geils performing in 1973. (Fin Costello)

And there’s my homeroom angel on the pages in-between

My blood runs cold

My memory has just been sold

My angel is the centerfold

The J. Geils Band toured incessantly until breaking up in the mid-1980s. Mr. Geils once estimated that, over a 14-year period, he was on an airplane one day out of three.

“Did a single J. Geils record alter the course of popular music?” music critic Anthony DeCurtis told the Boston Globe in 2004. “No. But they proved that you can go out night after night, set after set, win over audiences, and finally become successful.”

John Warren Geils Jr. was born Feb. 20, 1946, in New York City and grew up in Far Hills, N.J. His father, an engineer at Bell Labs, had a love of jazz.

Mr. Geils’s first instrument was the trumpet, and he saw jazz stars Louis Armstrong and Miles Davis perform when he was young. Switching to guitar in his late teens, he was inspired by blues stars B.B. King and T-Bone Walker and jazz guitarist Charlie Christian, who played alongside Benny Goodman.

“I’d hear a Charlie Christian record,” Mr. Geils told the Globe in 2006, “and say, ‘I wanna play like that!’ ”

He gave up his engineering studies at Worcester Polytechnic Institute in Massachusetts to pursue a career in music.

Mr. Geils and his group had occasional reunions over the years, but in 2012 he sued former bandmates for using the J. Geils Band name without his permission.

His marriage to Kris Geils ended in divorce. A complete list of survivors could not be confirmed.

Since the 1990s, Mr. Geils turned down his amplifiers and all but abandoned rock-and-roll. He had a large collection of vintage guitars and performed almost exclusively in jazz settings, releasing several albums of classic swing music.

“Throw all that weird stuff away,” he told the Sentinel & Enterprise of Fitchburg, Mass., in 2011. “Listen to the old masters. The old ones know. And now I’m one of ’em!”