The last time that Godsmack was in central Maine, the hard-rock band was already outstanding in its field.

Well, make that out standing in a field, anyway.

The year was 1999. The Boston-based group’s self-titled debut album was selling briskly, and yet the quartet honored its commitment to headline at Bumstock, the end-of-year, outdoor concert at the University of Maine.

Despite the hundreds of shows since then, bassist Robbie Merrill still recalls that cool evening in April in Orono: “We parked our butts out in the field, and wondered, ‘What are we doing here?’ I remember it was a cold night and a good show.”

Things have been looking up for Godsmack since then. The band has enjoyed three platinum-plus albums and more than 10 hit singles. Their latest, the acoustic “The Other Side,” has gone gold, and the quartet will be playing an acoustic concert at 8 tonight at the Bangor Auditorium.

Merrill said it wasn’t much of an adjustment for Godsmack, a band known for bombastic, pyrotechnic concerts, to go unplugged.

“We’d been playing acoustic on radio shows,” he explained. “We knew which songs would work and which wouldn’t. We had an idea what we wanted to do. We also had older songs that would work for this.”

“The Other Side” was recorded last year in Hawaii, where Merrill, vocalist Sully Erna, guitarist Tony Rombola and drummer Shannon Larkin took a working vacation. The album includes unplugged versions of “Realign,” “Keep Away,” “Spiral” and “Asleep” (a reworking of “Awake”) and three new songs. One highlight is the second single, “Touche,” recorded with vocalist John Kosco and guitarist Lee Richards of Dropbox, the first band signed to Erna’s new Realign Records label.

Merrill added that the acoustic concert features the songs from the album plus a few others the quartet had previously performed unplugged, including “Serenity” and “Voodoo.”

Response has been favorable to the acoustic format, the bassist said.

“At meet-and-greets after the show, I ask people how they liked it, and a lot of them like it better than our regular shows,” he said. “It’s fun to know that you can sit down and play and people still love you.”

Godsmack is doing “The Other Side” tour during a break in its U.S. tour with Metallica. They have enjoyed their time on the road with the hard-rock veterans.

“We have a lot of respect for them,” Merrill said. “They’ve been doing this for 20 years. They’re nice guys, and it’s been a lot of fun for us.”

After finishing up with Metallica at year’s end, the band hopes to go out for a few more acoustic shows early next year, then enter the studio to record an album that would come out next summer.

Will unplugged become a regular part of Godsmack’s repertoire?

“It depends on what’s going on at the time,” Merrill said. “I’m not sure if we’d put it into our rock show.”

Tickets are available at the Bangor Auditorium box office and all Ticketmaster outlets or can be charged at 990-4444 or 775-3331 and online at www.cc.com. Dale McGarrigle can be reached at 990-8028 and dmcgarrigle@bangordailynews.net.