Suddenly, Pogo Studio owner Mark Rubel feels differently about the jazz project he's been recording this week: He knows his friend and colleague, Jon Schoenoff, won't be mastering it and covering Rubel's work.

Mr. Schoenoff, audio director at Krannert Center for the Performing Arts and head of sound design for the University of Illinois Department of Theatre, died unexpectedly on Monday, at age 53.

"It leaves a giant hole," Rubel said. "He was so important to the function of the center, which is so important to the cultural life of this town. He had his hands in so many other things. It's really a tremendous loss, not only for the cultural world of our area and beyond but also personally for people who respected him and regarded him highly."

Mr. Schoenoff also composed music for theater and dance performances and wrote string quartets that were beautiful, Rubel said.

He mastered, or finished, Rubel's acoustic recordings and at Krannert and elsewhere recorded many classical musicians, among them Ian Hobson and Ollie Watts Davis.

At the university, where he began working in 1989, Mr. Schoenoff led what Krannert/Department of Theatre technical director Tom Korder called one of the top five MFA sound-design programs in the country.

"Jon was firm with his students but well-loved by them," Korder said. "I suspect there will be many of them coming back for his services (at 1 p.m. Friday at Krannert) because of the respect they had for him. He had a lot of graduate students out there who have gone on to do extremely well."

As a sound engineer, Mr. Schoenoff also consulted with theaters and churches nationwide and was a partner in Hobson's Zephyr Records label. He recorded many of Hobson's solo piano and Sinfonia da Camera projects and helped him edit them.

Hobson said Mr. Schoenoff was "extremely good" at what he did.

"On the technical side, he was superb putting together anything electronic and in the placement of microphones," Hobson said. "He came out of the theater milieu but he had quite a bit of musical understanding. He composed music and he knew how to balance and to edit really incredibly complex music."

Mr. Schoenoff was willing to collaborate with anyone and found it hard to say no, said Rebecca McBride, associate director of Krannert Center. David Spelman, artistic director of Krannert's Ellnora Guitar Festival, said he never heard the word "no" from Mr. Schoenoff.

"Whether the issue was as important as addressing a composer's complex audio needs for a massive sound installation in the lobby or as mundane as an artistic adviser requesting the right wires to connect an iPod in a hotel lounge, Jon always found solutions," Spelman wrote in an e-mail to Krannert staff. "And what's more, he always followed up to see if the solution was working well or if there was perhaps a way to make it work better. "

Like others who knew him, McBride described Mr. Schoenoff as quiet, understated and wry. When he did say something, what he said was right-on, McBride said.

Spelman called Mr. Schoenoff "faux-curmudgeonly." On the inside he was a teddy bear, Korder said.

The cause of Mr. Schoenoff's death has not yet been determined. McBride said he began to feel extremely weak and tired on Sunday and went to the hospital that day. He died at 5:55 the next morning.

Survivors include his wife, Barbara, who works in the Krannert ticket office, and two sons, William and Maxwell, both of Champaign.

Parking for Mr. Schoenoff's services will be free from noon to 3 p.m. Friday inside the Krannert parking garage.