Given Kevin Mahogany’s imposing size — a reminder of his gridiron days at Baker University — one might have expected him to start with vocal fireworks the second he took the Lawrence Arts Center stage Friday night — a Ruben Studdard for the jazz set.

Instead, Mahogany and his trio proved themselves possessed of subtlety and restraint, luxuriating at first in the softer, silkier regions of music.

“It’s kind of an evening of laid-back music, relaxing music,” Mahogany told the nearly full crowd.

The trio’s first seven-song set lasted a bit more than an hour, starting with straightforward jazz, moving to ballads and concluding with a blues number that got the audience clapping along.

“It’s a mandatory state rule I do two blues songs a night,” Mahogany said.

But it was the ballads — “When I Fall in Love,” “If I’m Lucky” — where Mahogany really shined. This reviewer searched in vain for someone to cuddle during those numbers.

The second seven-song set moved more freely between fast and slow tempos, starting with “Route 66,” which featured an extended back-and-forth scat-and-bass duet with bassist Chuck Bergeron. The set also featured expert renditions of the standards “Lush Life” and “Don’t Get Around Much Anymore,” as well as a fast-paced vocal version of the Ray Charles Orchestra instrumental classic “Hard Times.”

It was on the three-song encore, however, that Mahogany unveiled the full extent of his vocal skills, demonstrating range, volume and inventiveness.

His rendition of “My Funny Valentine,” though, was marred somewhat by a ringing cell phone in the crowd.

“I’ll get that,” Mahogany said before sliding back into the lyrics.

In 2004, audiences for any performing art should be sophisticated and considerate enough to turn the darn things off — or at least set to vibrate. C’mon Lawrence. You can do better.

Oh well. The evening finished with a rousing edition of “Kansas City,” a tribute to Mahogany’s hometown, and perhaps not incidentally, the name of the Robert Altman movie in which he played Big Joe Turner.

The evening was billed as a tribute to the late balladeer Johnny Hartman, best known for standards such as “Bidin’ My Time” and “I Just Dropped by to Say Hello.” Mahogany, a nationally known talent, proved himself worthy of Hartman’s mantle.

And Lawrence, with its excellent turnout for the concert, proved itself worthy of the new “Jazz at the Arts Center” series. The events could be a real boon to the cultural life of the city — as long as everybody remembers to keep their cell phones silent.