Dave Grohl. Superstar road-tripper next door? Old-school recording studio preservationist? 21st century rock-and-roll diplomat?

He’s all of those things in “Sonic Highways,” a new HBO rockumentary series that follows the 45-year-old rock mensch and his Foo Fighters as they traverse America’s asphalt arteries, recording their new album. Eight songs, eight recording studios, eight different cities. Along the way, Grohl finds time to interview the players, producers, scenesters and enthusiasts who made these cities hum — and then record a Foo Fighters ditty about what he’s learned.

[Related: Read Hank Stuever’s review of “Sonic Highways"]

The second episode of “Sonic Highways” airs on Friday night, and it focuses on Washington, D.C., a city whose musical heritage often defies tidy historicization. Grohl — a proud son of neighboring Springfield, Va. — spends the episode shining most of his light on Washington’s hyper-local go-go scene, as well as the hardcore punk scene that congealed in the ’80s around the activist group Positive Force, Inner Ear recording studios and Ian MacKaye’s pioneering independent punk label, Dischord Records. [Quadruple disclosure: My old band played numerous shows organized by Positive Force and made various recordings at Inner Ear with MacKaye for Dischord.]

I recently spoke with Grohl over the telephone about the challenges of the “Sonic Highways” project and the remote possibility of Foo Fighters going go-go.

Among other things, “Sonic Highways” proves that you’re interested in being a lot more than a guy in a rock band. Do you see yourself as a sort of global ambassador for rock-and-roll at this point?

Uh, no. [Laughs.] That would be pretentious and egotistical and a terrible way to see myself. Everything that I do, I do within this relatively small organization that is the Foo Fighters family. We’re on our own label. And we make records in our studio. And sometimes we make our own videos. We come up with the ideas for all of our projects on our own. We have aspirations and things we want to accomplish, but it’s simple: I love music. I want to share music with people. And I have the resources to do something like the “Sonic Highways” project. So to me, it’s just a labor of love.

How did your Washington visit stand out from the rest of the “Sonic Highways” trip?

One of the great things about the Washington, D.C. episode is putting the spotlight on go-go music and Dischord Records. Those are things we take for granted living in Washington, D.C. But if you travel outside of the city, a lot of people don’t know what go-go music is. A lot of people don’t know Ian MacKaye or Dischord Records. Those are the greatest examples of what I’m trying to communicate with this series: the regional relevance of music and how a specific sound comes from a specific place.

I remember the first time I traveled outside of Washington, D.C., I thought everyone had go-go music. And when I realized they didn’t, I couldn’t understand why. And Dischord Records — in this day and age, when everyone has access to independence, Ian MacKaye and Dischord Records are the best example of how to do it properly.

Did you learn anything while shooting the D.C. episode?

One thing I learned that was that the go-go pocket beat was something that Chuck Brown played between songs so the audience wouldn’t leave. He realized that when you stop playing music, you lose the crowd. So he would play these top 40 songs, and in between those, he’d throw this pocket beat in there. And that became known as the go-go beat. Very cool.

What got left on the cutting room floor?

My interview with Ian MacKaye was four and a half hours long. So yeah, a lot did! It’ll be the greatest criticism of this series: We didn’t cover enough in each city. There’s no way you can tell the history of music from a city in one hour. So we have to find a way to pay tribute to and honor these musicians, and their background, and their city — all while weaving in a personal journey with the band writing a song that will pay tribute to these people. It’s tough to get it all in one pop.

This project memorializes a lot of great American recording studios. But this wasn’t your first time at Inner Ear, was it?

I’d recorded at Inner Ear when it was still in [owner and engineer] Don Zientara’s basement. I recorded there with Scream and I remember walking down into that basement as if it were Abbey Road. “Oh my god, Rites of Spring recorded here!” It was like hallowed ground to me. And then later on, I recorded at the new facility after I was in Nirvana — I recorded some stuff there with my sister and one of those songs ended up on the first Foo Fighters album. But it was cool to see our bass player, Nate [Mendel], walk down the hallways and look at all the albums that had been made there, realizing that the soundtrack of his youth was on the walls.

There’s a moment in the D.C. episode where you and Big Tony from go-go legends Trouble Funk talk about a collaboration. Will the next Foo Fighters album be a go-go album?

We’ve talked about collaborating. And once our schedules line up and it comes together, I’m sure it would be the bomb. But we haven’t figured it out yet. It’s a matter of time. We’re on a collision course for sure.

There’s also a moment on screen when [Foo Fighters drummer] Taylor [Hawkins] says that since you’re from D.C., that kind of makes Foo Fighters a D.C. band. Can we officially claim you?

I never tell anyone that I’m from anywhere. Well, I tell people I’m from Virginia, per se, and they say, “Virginia?” And I say, “Well, Washington, D.C.” [Laughs.] But it’s a huge part of who I am and I wouldn’t be this person if it wasn’t for that place and those people. I’m proud to say that. I’m proud to be a musician from the Washington, D.C. area. Musically, it’s a lot richer and more vital than most people would ever expect.

[From 2011: Dave Grohl, glancing back, blasting forward]