Charles Vernon, the Chicago Symphony Orchestra’s internationally known bass trombone player, is no stranger to world premieres. He performed the debuts of two concertos with the CSO in 1991 and 2006, and by 2015, he was ready to tackle a third.

Vernon narrowed the list of composers down to four finalists, and then after consulting with Music Director Riccardo Muti, the trombonist settled on James Stephenson of Lake Forest, Ill. “I’ve listened to a lot of things he’s written over the years,” said Vernon, who will perform the world premiere June 13-15 of Stephenson’s Bass Trombone Concerto with the CSO and Muti. “He’s written several trombone pieces, and I’m played at least one of them quite a bit. I was interested in the way he wrote. He understood the instrument fairly well. The main thing is that I liked his music. I just liked the way he composed.”

Stephenson, who grew up in Lockport. Ill., and earned a degree from the New England Conservatory of Music in Boston, became a full-time composer in 2007 after playing trumpet for 17 seasons with the Naples Philharmonic in Florida. John Bruce Yeh, the CSO’s assistant principal clarinetist, has called the composer “The Concerto King” because he has written works in the form for virtually every instrument in the orchestra.

Many listeners might not be that familiar with the bass trombone, the lowest-pitched member of that instrument’s family other than the rarely heard contrabass trombone. It has the same nine-foot tubing length as a tenor trombone, but its wider bore, larger bell and bigger mouthpiece give its sound a darker, heavier consistency. “The tenor trombone is great up high, and it’s great in the middle register, but the bass has this flexibility that makes smoothness extremely possible in the low notes and the low register,” Vernon said. “It also has a wider range than the tenor trombone and offers a rich mix of tonal colors across its registers. “It’s the best one of the trombones, for sure,” he said. “I think it’s a great instrument or I wouldn’t be playing it.”

It took about two years for the concerto project, underwritten by the Edward F. Schmidt Family Commissioning Fund, to get started, and during that time, Vernon spoke often with Stephenson: “I talked to him, and said, ‘I want the greatest piece you’ve ever written in your life. I want a piece that’s got beautiful sounds in it. It’s emotional and has tons of singing, legato playing and excitement — all these kinds of things.’ And his reaction was, ‘Thanks, Charlie, no pressure.’”

When Stephenson sent Vernon an early draft of the solo part for the concerto, the trombonist was not entirely satisfied. “He didn’t understand me playing the bass trombone,” he said. “He understood the instrument fairly well, but he didn’t understand what I wanted as well as I had hoped.” So the two had further conversations, with Vernon explaining how certain passages didn’t suit his playing style and how others just didn’t work on the bass trombone, including too many sections in the instrument’s middle or upper register. “If I played this on the tenor trombone, it would be no problem,” he said. “But on the bass trombone, to play in the register of a baritone singer or even a tenor singer for 80 measures in a row, it’s just too taxing.”

At the same time, Vernon asked for a few more rests, because of a need to catch his breath during the extended solo passages. “I’m 71 years old,” he said, “and I’m doing OK, but when you’re talking about somebody who is 25 or 30 and is 6-foot-8-inches or something like that, they’ve got big lungs and some issues with breathing are not a problem for them. That’s just the way it is.” He remembers his teacher, Arnold Jacobs, the CSO’s principal tubist from 1944 through 1988, having some of these same challenges later in his career. “At that time, I didn’t really pay that much attention to it,” he said. “I thought, ‘Well, yeah, some day.’ It’s ‘some day’ now.”

Stephenson accommodated as many of Vernon’s wishes as possible. “He was really responsive to doing the things that I asked, and the final product is really good,” Vernon said. “It’s really good for me to play. It’s exciting for me for me play. It’s a challenge for me to play, and it’s going to sound great. I’ve been playing with piano to learn the piece, but I know when I stand up there and have the Chicago Symphony behind me, this is going to be another universe.”

The 22-minute concerto is divided into three sections: Chapter I, Chapter II and Epilogue, all corresponding to the different stages of life. According to Vernon, the epilogue was inspired by the death of Stephenson’s mother and the emotions evoked by that milestone event. “It really appealed to me, because my mother passed away in March of ’18, and he had this Epilogue, which corresponds to my feelings and the things that went on with my mother,” Vernon said. “So emotionally speaking, I can really tap into that and think of that while I’m playing. That’s the whole thing about playing music, that you are able to express emotion from your mind through an instrument and out to the public.”

Stephenson writes in a down-to-earth, tonal style. In a 2018 Sounds and Stories interview, he described himself as a “creature of tradition” at least to some degree, and he is careful to provide entrées into his music for listeners through his choice of musical forms or use of repetition. “But within that, I’m always searching for new sounds, new pairings of instruments and new rhythms and textures, so my music still has a freshness to it that is maybe new and familiar at the same time.”

Vernon described the concerto’s musical language as beautiful and tuneful. “I told him in the very beginning that I don’t want any mutes in this,” he said. “I don’t to play and bang on the trombone. I don’t want to buzz the mouthpiece and make guttural sounds — that kind of stuff that I hate. I want song and beautiful music, and it’s glorious.”

The first of Vernon’s two previous debut concertos with the CSO was Ellen Taaffe Zwilich’s Concerto for Bass Trombone, which was commissioned for the orchestra’s centennial in 1991. “There are some pretty moments in it, but it was an unbelievable show for me to play,” he said. “I feel if I can play that piece, I can play any piece. I had to be in the best shape of my life to play it.” In 2006, he performed the world premiere of Christian Lindberg’s Chick’a’Bone Checkout, which called on Vernon to alternate among the alto, tenor and bass trombones. He has gone on to play that work 25 times all over the world.

But Vernon believes that Stephenson’s concerto might be the finest all-around work yet written for the bass trombone.  Best of all, he said, the piece is composed in such way that any serious student or professional player should be able to perform it. “That’s why I wanted it written in the first place, to have something that would just take over,” he said. “If they wanted a bass trombone solo, this would be it. This is what I’m hoping for.”