Alter Bridge has altered its sound — a bit — on its upcoming sixth album, “Walk the Sky.”

“I called Myles one day and turned him on to a song that I really dug, that style, and he immediately responded and said he loved it, and that was the [filmmaker] John Carpenter-esque synth-wave stuff from the ’80s,” Alter Bridge guitarist Mark Tremonti says, referring to lead singer and guitarist Myles Kennedy.

“I attribute some of this to the post-‘Stranger Things’ era that we live in, where I think it was in our collective psyche,” says Kennedy, who along with Tremonti recently sat down with The Post in Midtown to talk about “Walk The Sky,” out Oct. 18. “It was rather odd, frankly, that he sent it, because that was exactly what I had been thinking.”

But head-banging fans of Alter Bridge needn’t worry — the group hasn’t gone full Pet Shop Boys. At its core, the 14 tracks on “Walk The Sky” are a progression, not a departure, from the metal-influenced, guitar-driven hard rock that has earned the band a gold-selling debut album, a concert film that topped Amazon’s music video sales and slots on major festivals in the US and Europe.

Lyrical inspiration for the album came from the likes of American mythologist Joseph Campbell (on “Native Son”) and the 2015 film “The Big Short,” about the subprime mortgage crisis (on “Pay No Mind”).

The easy rapport between Kennedy and Tremonti during the interview is emblematic of their songwriting partnership over the course of the band’s 15 years.

“We just respect one another’s opinions, and we we both work very hard,” says Tremonti. “This is all we’re good at.”

“We’re idiots,” Kennedy chimes in.

“We do this around the clock. This is our creative outlet together,” Tremonti continues. “We try to balance one another out. I think when we first came together we were two different styles of writers, and I think we’ve crossed those lines over the years and become a more cohesive unit.” That fact was driven home when long-time producer Michael “Elvis” Baskette told Tremonti, “I can’t tell who wrote what on this album.”

The two have regular projects outside of Alter Bridge — which also features bassist Brian Marshall and drummer Scott Phillips, who played with Tremonti in the band Creed. Kennedy has been working with Guns N’ Roses guitarist Slash since 2010, and Tremonti has been leading his namesake band since 2011, where he sings lead vocals. Both musicians say their outside ventures have colored how they approach their roles in Alter Bridge.

“When you do the frontman thing live and you step back into another band where [Kennedy is] carrying the weight of the entertainment of the crowd, you can you can just feel more confident,” Tremonti says. “You can do more and feel more comfortable in your skin up there after you’ve done that.”

“I think one of the things that’s rubbed off on me with Slash is his work ethic,” says Kennedy. “It’s pretty intense. He’s just relentless, and I think seeing that is inspiring, especially that he’s had the amount of success that he’s had, he doesn’t have to do that. He can kind of just rest on his laurels and be like, ‘OK, I’ve done this, I’m good, and I don’t have to work this hard anymore.’ It almost feels as the years go on he wants to work harder and harder and harder. I don’t know where it comes from. I think it’s just for the love of the game.”

Alter Bridge will bring its Victorious Sky Tour to PlayStation Theater on Tuesday with fellow hard rockers Skillet and Dirty Honey. It’s a safe bet many of the fans will be repeat customers. (The show was originally scheduled for Terminal 5 but was moved after a minor fire there last weekend.)

“They’re like Deadheads. We literally have fans that have been to 200-plus shows over the last five years,” says Kennedy. “And they all get to know each other. They travel together, they go to each other’s homes.”

“They get married,” Tremonti says.

“It gives me the feels,” Kennedy says. “I love seeing that music is bringing people together.”