Heart’s Ann and Nancy Wilson are on a tour bus somewhere outside Salt Lake City, heading for yet another concert on yet another stage. The duo expects to complete 55 dates this year; last year, they did 90—two a week, nearly every week. So much for taking it easy after 35 years in the business and 35 million albums sold.

Rockers are supposed to mellow with age, but Ann, 62, and Nancy, 58, have rarely done what they’re supposed to do. No Great American Songbook for the sisters who set millions of heads banging with “Crazy on You,” “Barracuda,” “These Dreams” and “Magic Man.” “Any time anyone says ‘jazz standards,’ it makes my butt tingle,” says Ann. “Do that, and your rocking days are over.”  “We wanted people to know we’re not getting ready to take a dirt nap,” says Nancy.  “We’re still trying to save the world, one song at a time.”

More tough than tender, their new album Fanatic compares comfortably to anything on Little Queen or Dreamboat Annie. Ann wrote most of the songs on the tour bus. Not on tour—just on the bus. While everyone else took a short break, she motored from L.A. to Cincinnati and back. “It was like being in a moving artist garret,” she says. “There was nothing to do but write.” The 10-song CD was recorded mainly in motel rooms up and down the West Coast. The sisters also recently penned their memoir Kicking & Dreaming, A Story of Heart, Soul and Rock & Roll.

Has the digital world changed your creative process?

ANN: There was a time we would say, “Someday in the Jetsons future, we will be able to send each other a demo tape through the air.” Now we do it all the time.

NANCY: The creative part of this album was as old-school as we could make it—sitting in a room, thinking out loud together, actually playing at the same time. Capturing and recording is done with modern technology, just because it’s really hard to get a hold of a tape recorder anymore—which is fine; we used to have to sit there and wait for tapes to actually rewind.

ANN: We take advantage of the part that makes it easier to capture the music, and fight the cold, brittle sound of digital. There’s something harsh about the way digital sounds, which, if you were born in the age of analog, you can really hear.

NANCY: Also, with digital it’s harder to be creatively decisive. For every edit and loop, every instant the possibility of changing your mind is right in front of you. We used to be forced to decide which take was best and build on it. Having everything at your fingertips is convenient but does not always help develop creative decision-making skills.

ANN: The moment will always come when you have to say, “No, that’s it, take your hands off.” The songs have a voice—they tell you what they want you to do.

How did writing a book differ from writing songs?

ANN: Writing a book is like therapy. When you’re going over all that ground of being 13, when you figured your life was hell—you have to pull out all the stops.

NANCY: There were so many “aha moments” about the connective tissue in the family. As a kid you tend to rewrite history. I wish I’d kept a better personal journal. But the songs are like a diary.

ANN: I’m sure I’ve forgotten tons of incredible stuff because I can’t be bothered, or I’m too much in the moment to sit down and go, “Let’s see, what happened today?”

Which song came easiest, which song was the hardest?

NANCY: The title song, “Fanatic,” came easiest. I was jamming with Ben Mink, our producer, and the guitar riff that starts the song just came rolling right out of me. It felt larger than life and righteous and fun.

ANN: I would say that “Dear Old America” came the easiest for me. I had written a big ol’ bunch of words on the bus—all we had to do was find a swagger groove for it. It all fell into place. The hardest was “Million Miles.” We were doing a tip of the hat to the old folk song “500 Miles,” but we didn’t want to get too close to it. We wanted to make it our own song.

NANCY: The toughest for me was “Walkin’ Good,” because that day I kept trying to text with my new boyfriend [now husband, Geoff Bywater] and could hardly pay attention in the studio. Ben Mink had to keep going, “Excuuuse me. Could you please put your cellphone away and get to work?” Also, I sing on that one and I’m not the best singer in the world. I’m a player who loves to sing.

In this case, a player who sings with Sarah McLachlan (on “Walkin’ Good”). How did that come about?

NANCY: We played on her tour last year, and our producer is a friend of hers in Vancouver. She really liked the song and related to the theme of it.  Plus she sounds really good on it.

An appeal to a more AAA audience?

NANCY: Yes, but that’s also me. Usually there’s a “Dog and Butterfly” along with a “Barracuda”—it’s the yin and yang of a rock band.

ANN: We have a couple of songs on every album that are more mellow.

Is rock the music of youthful sexuality?

NANCY: When you’re on a rock stage, it’s timeless and ageless and very sensual. I’m more an adult and more a teenager now simultaneously.  Especially as a newlywed!

ANN: Honestly, I feel freed up from some of that stuff. I no longer labor under the handicap of having to look like a little show pony. If I can go out there and look my own beautiful way and do the best I can singing, then I’m satisfied. And I couldn’t have said that 20 years ago.

What’s in your arsenal, and why?

ANN: I sing through a Sennheiser wireless mic—we use them in the studio, too, but not wireless. I play a Gemeinhardt flute. I’ve tried some wooden flutes that have a more beautiful sound, but they don’t hold up to life on the road. So I play a Gemeinhardt student flute just like the kids in school band. And I play a custom Martin acoustic guitar called the Cosmo, based on the Johnny Cash black Martin.

NANCY: There’s a guitar I designed with Gibson in the ’90s called the Night Hawk that I rediscovered and used on Fanatic. It’s a really strong guitar with the crunchiest, fattest sound. I use a bunch of different acoustic guitars, but mainly a custom-made one, and a Martin signature acoustic. The holy trinity: two acoustics and an electric.

Clearly, the creative well is far from dry.

ANN: There’s always a bunch of stuff hovering. If you’re lucky enough to pull down the right one, a whole bunch of stuff comes down with it, and you’ve got yourself a song that will get you really excited. It comes easy after that.

–Ethlie Ann Vare