Blues fans are mourning the death of Mike Ledbetter, a singer and guitar player whose powerful vocals wowed audiences in the U.S., Europe and Russia.

He was 33, according to friends. Mr. Ledbetter died of a sudden medical emergency Monday at his Elgin home, and his family is awaiting autopsy results, said his manager Gina McClain.

“He was scrupulously healthy,” said “Monster” Mike Welch, his bandmate in the Welch-Ledbetter Connection. “On and off, he was a bodybuilder. There’s no lessons about the pitfalls of the road. This is a man who took care of himself, loved his kids, loved his girlfriend Kathy.”

Trained in opera, he was “truly the best vocalist. . . .He was just passionate about American music,” said Tina Terry, his agent. “For the blues community, it’s a huge loss.”

Mr. Ledbetter was a 2019 Blues Music Award nominee in two Blues Foundation categories, vocalist of the year and “B.B. King Entertainer.” The Welch-Ledbetter Connection is also up for band of the year. In 2018, he and Welch won a Blues Music Award for best traditional blues album for their Delta Groove LP, “Right Place, Right Time.”

Mr. Ledbetter grew up in Elgin and went to Elgin High School. He once toured with the Nick Moss Band. “My wife saw him sing one night, and brought him to my show at Rosa’s” lounge, said Moss. He joined Moss onstage “and basically stole the show that night. Next thing I know is he is in my band and we toured the world for seven years.”

The Welch-Ledbetter Connection was to perform at the Chicago Blues Festival this summer, Terry said. And Mr. Ledbetter was also set to play upcoming dates at Kingston Mines, B.L.U.E.S., Callahan’s Music Hall in Auburn Hills, Michigan, and at Buddy Guy’s Legends, where officials posted on Facebook Monday that the club was “deeply saddened” at his death.

Fans said he moved them by conveying the meaning of songs, rather than showing off his big range. “It was like he was telling his own story,” Welch said. When he sang, “I heard someone who was able to embody the entire tradition of Chicago blues and rhythm-and-blues.”

“He could be transcendent in the moment and also scratching the surface of what he was going to be capable of in the future,” Welch said. “I’m sorry I didn’t get to hear what he was going to do next.”

“He’s got soul not only in his voice,” Moss said. “The guy was one of those undeniable personalities.”

Mr. Ledbetter told Blues Blast magazine he grew up listening to his father’s B.B. King “Live at Cook County Jail” LP, as well as his sister’s favorites: Michael Jackson, Prince and New Edition.

But he was molded by Otis Rush. As he prepared for a 2016 tribute to the bluesman, he told the Sun-Times “Otis Rush is my biggest influence when it comes to blues music. Vocally, instrumentally, everything–he’s been my No. 1 influence.”

Mike Ledbetter and Mike Welch - Tribute to Otis Rush! Posted by Chicago Blues Festival on Sunday, June 12, 2016

He performed throughout the U.S., in Belgium, the Czech Republic, Denmark, France, Germany, Norway, Russia and Switzerland.

McClain and Welch said Mr. Ledbetter was a distant relative of blues legend Leadbelly.

In addition to his partner Kathy Cahoon, he is survived by their two children, friends said. Funeral arrangements were pending.