Rock-and-roll. It’s still happening, somehow. Still fast, still fun. But play it too fast and the fun goes slippery. Too slow and the fun dries up. So rock-and-roll requires exactitude, and abandon, and never totally getting it right because totally getting it right would be all wrong.

Washington rock trio Ex Hex at Comet Ping Pong, the Northwest pizza-restaurant-bar-rock-venue that’s become one of the band’s local haunts. From left to right: drummer Laura Harris, bassist/vocalist Betsy Wright and guitarist/vocalist Mary Timony. (April Greer/FTWP)

Tonight the band is Ex Hex and the song is “Hot and Cold,” a neo-glam ditty about a telepathic romance on the fritz. They’re playing it too fast. So instead of counting off with the primordial clack of drum sticks, the trio is using an amplified digital metronome.

BLEEP. Bloop. Bloop. Bloop.

BLEEP. Bloop. Bloop. Bloop.

“Really?” asks Mary Timony, the band’s leader and guitarist, scrunching her face. “Feels so slow!”

But machines don’t lie and time waits for no one, so Timony rolls up her denim sleeves and peels into the riff as if channeling classic rock radio from the future.

“These songs, if they get too loose or too fast, they just don’t work,” she explains when it’s over. “So, as a band, we’re just this weird combination of meticulous and totally not.”

Bassist Betsy Wright circles the room – a warehouse practice space in Northwest D.C. that Ex Hex shares with Death Fix, Priests and at least one mouse – cradling a bottle of cheap champagne. As she tops off her bandmates’ plastic flutes, jokes fly about how every Ex Hex song is worthy of a celebration.

Or maybe they aren’t joking. Timony, Wright and drummer Laura Harris came together after stepping away from an assortment of broken-up bands and broken-up relationships. And while the trio took its name from the title of Timony’s 2005 solo album, the “Ex Hex” sounds like something they’re trying to escape.

“We all got really committed right away,” Timony says of the new band. “And me, I’m desperate to play rock music always.”

Her discography proves as much. Timony got her start in the overlooked D.C. punk quartet Autoclave, but by 1992 she had moved to Boston to front Helium, an inventive and beloved indie trio that pursued medieval melody with electric guitars. She went solo in 2000, and in 2009 she signed up for Wild Flag, a punky supergroup that crumbled even faster than it was assembled.

Timony says Ex Hex – which formed just last spring and is already set to release its debut album, “Rips,” on Merge Records this month – is different.

“I feel like this band is the most fun band I’ve ever been in.” Then she pivots to Wright and Harris and asks, “How did that happen?” They answer with shrugs, laughs and swigs of champers.

And as they resume rehearsal, it feels like there’s some casual myth shattering going on here – the myth that significant art must be born out of struggle, or competition, or the itchiness of a tour van with weak air conditioning.

But this is a band about trust, and having a laugh, and not playing too fast, and making sure everyone’s drinking lots of water, and the idea that maybe great rock-and-roll can be made out of that stuff, too.

“I feel like this band is the most fun band I’ve ever been in,” says Timony, left, of Ex Hex. (April Greer/FTWP)

It’s Friday night and Harris is en route to what must be her thousandth shift at the Black Cat, the venerable 14th Street rock club where she’s been working since she was 19 years old. She’s 32 now. Doesn’t she ever get sick of spending her nights shouting over other bands’ decibels?

“No way, man,” she says. “When you’re not playing, it makes you crazy to play.”

Harris grew up in Northern Virginia and taught herself to play drums by pantomiming the Keith Moon beats rumbling out of her Discman headphones.

From that point forward, she started “faking” her way into bands. “It’s kinda my M.O.,” Harris says, and in her 20s, she faked her way into a few. One was the Aquarium, her almost-prog duo with guitarist Jason Hutto. Another was with Benjy Ferree, a D.C. songwriter signed to Domino Records who was then Harris’s boyfriend and is now her ex-husband.

“It’s hard being married and playing music together,” Harris says. “You have to be empathetic, and giving, and pride-less,” not really specifying whether she’s talking about the music part, the marriage part, or both.

With everything dissolving, two tough years went by without Harris playing a show. Then she got a phone call from Timony asking her to jam.

“That call was really a gift,” Harris says. “Getting divorced, being lost musically and artistically, I had no idea what I was going to do. I was turning 31, which is that time in your life when you’re wondering what’s going to happen. Saturn’s return and all that. So when Mary called, it was like, ‘Yes, yes, yes. I can play again.’ ”

Ex Hex performing earlier this year at Merge 25, a festival hosted by its label, Merge Records. (Photo by Matt Condon)

“Rips” is a cool and forthright name for this album – it pretty much describes what it does. As a songwriter and a guitarist, Timony has never sounded more polished or more poised. But two songs on “Rips” offer a different swing and shimmer: “Radio On” and “How You Got That Girl.” They were written by Wright.

She’s been playing music since she was a 6-year-old Madonna-obsessive who spent her weekend afternoons in the basement listening to her dad’s old 45 collection. “You know, pop stuff like ‘Lollipop’ and ‘Daddy Cool,’ ” the 34-year-old says, sipping tea at a Northwest coffee shop.

Wright attended high school in the District, becoming a self-described “classic rock kid” before shuttling off to Bard College to study jazz piano, finally finishing her music degree at George Mason University. Along the way, she played keys and sang in Washington’s underrated Childballads and later fronted the Fire Tapes alongside her now ex-husband in Charlottesville, where she was earning her graduate degree.

Last summer, Timony heard Wright was moving back to the District and phoned her after she’d recruited Harris. The threesome’s shared love for Johnny Thunders and the Ramones made for a seamless match. All Wright had to do was get her hands on a bass guitar and teach herself how to play it.

She says she learned quickly, but “the kind of music we play is so simple, everything has to be in the right place. There’s only three of us and there’s nothing covering anything up.”

That minimalist aesthetic requires trust – a trust that Wright says has brought the three closer. In a way, their friendship is coded in the music.

Wright noticed that Ex Hex was different once they started posing for promo photos: “We’re all smiling at each other. And up onstage, we’re always laughing and having fun. I feel like I don’t see that at shows. And that stuff is really real! When Mary is taking a guitar solo, I’m just freaking out.”

Like an Ex Hex song, Timony’s row house in Glover Park is relatively tidy but punctuated with telling little messes. A motley stack of punk LPs sits on the living-room floor. Over on the kitchen counter, a scattered haul from the produce aisle creates a miniature alien landscape.

Timony says she writes her songs in the adjacent room, noodling around on her old Silvertone, ready to record worthy guitar riffs on her iPhone whenever they show themselves.

“What are my ideas?” the 44-year-old asks herself. “I don’t know. I’m just going to play guitar until they come out. When you sit down to play guitar, it’s almost like you’re dreaming.”

That approach shouldn’t surprise fans of Helium, a band that straddled the crunchy-guitar mood of the era and a day-dreamy equanimity that still belongs to Timony alone. She says she cringes when she listens to her old albums, wishing the guitar tones were different, wishing her voice sounded stronger.

“It’s not the ’90s anymore and you can’t get by with whining on stage,” Timony says. (She recently took some voice lessons.) “I became a mature rock musician in the early ’90s, when it was cool to have a [lousy] voice. People thought it was more authentic, I guess?”

After issuing some highly imaginative and introspective solo albums in the early ’00s, Timony made her biggest post-Helium splash in 2011 with Wild Flag, a group that included former Sleater-Kinney bandmates Janet Weiss and “Portlandia” star Carrie Brownstein. The band generated big excitement, then went poof. Timony wasn’t really clear why.

“I was the one on the East Coast who didn’t know anything,” Timony says. “It was really Carrie and Janet’s thing. Carrie has a lot of things going on, and I think this whole acting thing is what she really loves to do. . . . It was fun. But it was really more of a project thing.”

So she started stockpiling Ex Hex riffs, trying to reconnect with her 12-year-old-kid self, a tweener who loved Blondie, the Knack, .38 Special, Slade and Sweet. That nostalgic starting place might have had something to do with the fact that Timony spends her workdays teaching guitar lessons to tweens plugging into the magic of music for the first time.

With the band’s debut album “Rips” landing on Oct. 7, Ex Hex is embarking on a full tour of the U.S. (April Greer/FTWP)

“Guitar for me when I was a kid, it became my identity,” Timony says. “So I don’t really hate any music anymore, because I ask the students what they like about music and what they want to learn. So that means I’ve had to learn ‘The A Team’ by Ed Sheeran and all the Miley Cyrus songs.” (She also had to learn a bunch of Brian May solos – something you can certainly hear
on “Rips.”)

So she’s making music she loves with people she loves. But you can still hear little flecks of anxiety in Timony’s speech. The simpatico lightness she shares with Wright and Harris has finally given her the opportunity to focus hard on her songs, and now it’s time to let everyone else hear them. In a few days, she’ll be playing them on tour. It’s all happening really fast. It’s probably gonna be fun.