Tonic Sol-fa's Shaun Johnson likes to compare his Minnesota a cappella group to megastars like the Rolling Stones and Metallica. Excuse me, what?

"When I read biographies of these giants, so many of the things they went through, we did on a microcosm level," Johnson said. "At one point, the Stones recorded in a castle in France because of tax reasons, and Metallica was going to a counselor. All of these things happened to us."

Yes, group therapy, record label bankruptcy, tax issues, legal problems, personnel changes, embezzlement, just to name a few challenges.

Now, after 30 years, Tonic Sol-fa is calling it quits. The End of an Era Tour visits Burnsville's Ames Center on Friday and Saturday.

"We kind of stopped touring at the end of 2022," Johnson said. "At that point, everyone was doing a lot of different things and we needed a break."

But they also needed closure, a chance to say goodbye to fans in places they've been visiting for years in the Upper Midwest.

On the End of an Era Tour, fans likely will get to hear Tonic Sol-fa's most requested tunes, the originals "Oklahoma Wind" and "Chances" as well as an interpretation of "Cecilia," the Simon & Garfunkel tune. And a Christmas favorite because Tonic Sol-fa was a regular on the holiday circuit. (There might be a farewell holiday jaunt at some point, Johnson says, called the Wrap It Up Tour.)

Tonic Sol-fa began as an a cappella quintet at St. John's University in Collegeville, Minn.

"When I started, I thought: 'Oh, I will sing and it will magically work' and it did for a while," said Johnson, who had planned on going to law school after college.

Tonic Sol-fa became a small business, a do-it-yourself endeavor where the St. Cloud-based members took care of the booking, ticketing, marketing, promotion, the books and, of course, the musical arrangements.

Two decades ago, Johnson hired Michelle Massman to help because she knew more about the music biz than he did.

Tonic Sol-fa succeeded, performing in every state but Washington (yes, even Alaska and Hawaii) as well as Mexico. They've appeared at 27 state fairs and self-released 20 albums. They used to do 200 to 300 shows a year, including 52 in September alone one year. And they even have 401K plans for their members. How many bands can say that?

"The only thing I've ever done since college is sing," Johnson said. "There's something kind of cool and weird about that. A grown man singing a cappella is very unique. Like selling cassettes door to door."

Of course, there were bumps in the road. Personnel changes, though there's been a core threesome of Jared Dove, Greg Bannwarth and Johnson for the past 25 years. At one point, they worked with a counselor so the members could get along better. They landed a national record deal but the label went bankrupt right before the release of Tonic Sol-fa's album. The singers got married and had kids but that didn't disrupt the harmonies.

However, Tonic Sol-fa reached a fork in the road when Mark McGowan, who with Johnson was one of the principal owners of the quartet, embezzled more than $27,000 from the group from 2010 to 2014.

"We tried to work through it," Johnson recalled. "And that didn't work. It turned into this crazy time."

Johnson kept calling McGowan and then he didn't show up for a gig in Iowa.

"Finally we got a note from a lawyer who said he's not talking to you and he wants all this money. So we had to go do all these shows as three of us. I had to learn how to run sound."

With McGowan's refusal to leave the group, Johnson couldn't take out any loans or do any fiduciary business for Tonic Sol-fa. So, at the urging of his lawyers, the bandleader threatened to file a lawsuit unless McGowan quit that day.

"That's all we wanted. There was no negotiating. I got the paper faxed to me. I have no ill will. I wish it hadn't happened."

Tonic Sol-fa carried on as a trio for about a year. Then Theo Brown sat in for a while and eventually joined full time about 12 years ago.

Brown, a singer and pianist, was also part of Johnson's other project, the Shaun Johnson Big Band Experience, which started as a way to raise money for high school music programs.

"Tonic Sol-fa plateaued. I felt a need to build something again," said Johnson, who moved to Sioux Falls, S.D., his wife's hometown, about 10 years ago. "I had to find all these musicians; I knew nothing about that world."

The big band kept growing. By 2018, Johnson got an agent. In 2022-23, Tonic Sol-fa opened for the Shaun Johnson Big Band Experience's tour.

Both groups are preoccupied with musical arrangements. Even though the big band has eight members, it's easier to work out the arrangements.

"With the big band, I'm surrounded by people who are professors and people who can arrange music for hours. I can't do most of that," the bandleader said. "When you get to rehearsal, people come ready. They've all practiced."

With the four guys in Tonic Sol-fa, well, rehearsals are more consuming. "Greg is the de facto arranger. Everybody puts in their two cents. We sit around: 'Does this vowel sound better than this?'"

Tonic Sol-fa

When: 7:30 p.m. Fri.-Sat.

Where: Ames Center, 12600 Nicollet Av. S., Burnsville.

Tickets: $48 and up, ticketmaster.com.