To paraphrase Walt Whitman: Josh Groban is large, he contains multitudes.

There’s the Groban heard on his eight studio albums: operatic vocals, dramatic musical motifs and lyrics that are often serious, grappling with themes of love, unity and family (as on his most recent set, “Bridges,” released in September 2018).

Then there’s the Groban of social media and the stage, who isn’t afraid to get a little (or a lot) silly. Recent Instagram posts feature the singer sitting cross-legged in a shirt with the slogan “Josh (expletive) Groban” (only with an actual swear word in there), covering his face with bananas, and hanging out with his dog. And in April, Groban debuted on “The Simpsons” as the singing voice of Springfield’s Jerry Lewis-inspired mad scientist, Professor Frink.

Groban’s silly and serious sides will come together in his Les Schwab Amphitheater debut Tuesday. For the Los Angeles-born singer, songwriter, actor and Tony-nominated Broadway star, letting loose is one of the most important parts of his performances.

“If I can’t go complete goof ball between the songs and make people laugh — take the pie in the face to wipe away the tears — then I feel like I’ve failed that night,” Groban said from home in New York City. “For me, my shows — and especially these shows in such gorgeous venues such as Schwab — they have to have that element because the spirit of the night is that way — it’s loose, and it’s fun. That’s the biggest thing. When people feel like they’re taken to a show that they didn’t previously know a lot about me or my music, that’s always my favorite thing to hear of, is just how much fun they had.”

Groban’s energy was palpable even in a 15-minute phone conversation as he moved rapid-fire through topics including his new album, the current tour and the aforementioned “Simpsons” cameo. Speaking of, yes, Groban is a big fan of the show and remembered catching the very first episode with his brother as kids.

“I remember my brother and I just found it so hilarious from moment one,” Groban said. “And for those of us who grew up with shows like that, of course you get that call and you’re just like, ‘I will move mountains to get into the studio and do something.’ There was an episode that used me as a plot point, but I never actually did any vocals on. There was an episode where Lisa Simpson becomes a huge Grobanite and becomes a huge fan of mine, much to the chagrin of Homer. This was an opportunity for me to actually go in and sing something.”

Along with “The Simpsons” and his starring role in the Netflix series “The Good Cop,” also featuring Tony Danza, Groban has been equally busy on the music front. He returned to songwriting on “Bridges” following a four-year stretch in which he immersed himself in musical theater, starting with 2015’s Broadway covers album “Stages” and leading into his 2016 Broadway debut in “Natasha, Pierre & The Great Comet of 1812.” In April, Groban released the CD/DVD set “Bridges Live: Madison Square Garden,” a recording of his November show at the famous New York City venue.

“So many of the songs on ‘Bridges’ came from personal stories I wanted to tell,” he said. “I had made a musical theater album, and then, I immediately went onto Broadway, so I spent about four singing other people’s music and loved it. First and foremost, that’s what I do — first thing I would call myself is a singer and song interpreter, and the writing is something that happens when it feels really right. And it felt right; there were a lot of those stories that popped out on this album.”

A duet with country singer Jennifer Nettles of Sugarland on the appropriately Nashville-esque “99 Years” fits the theme. (Nettles guested on tour with Groban earlier this year, but will not be at the Les Schwab show.) The song, co-written with album co-producers Bernie Herms and Toby Gad, pays tribute to Groban’s parents, who recently celebrated 50 years of marriage.

“I was talking to them over dinner about what it took to get there, and they just basically said that it’s not about focusing on the destination,” Groban said. “It’s about making sure you get through the thick-and-thin of everyday moments together, and before you know it, you look back on this scrapbook of extraordinary memories — of love and good moments and bad moments that you held hands and got through together and made each other stronger with. I was so taken by that, and I’ve always seen my parents deal with every situation with such grace and humor and love, that it was just kind of a song that represented that ideal.”

Another collaboration, an Italian-language duet with opera singer Andrea Bocelli on “We Will Meet Once Again,” brings Groban’s story full circle. Early in his singing and acting career, a 17-year-old Groban subbed for Bocelli at a rehearsal for the 1998 Grammy Awards, and met the singer later that night. While the two have collaborated since then, “We Will Meet Once Again,” which they co-wrote together, is their first recorded team-up.

“That was an incredible opportunity singing with him back when he was just getting started (in the U.S.),” Groban said. “And all these years later, to have written a song that we could do together was very special for me. I mean, this is eight albums in the making for us to finally get in the studio and record something together.”