Inside one of the square concrete rooms in the old EMF building near Central Square, space is at a premium. Singer-songwriter Ruby Rose Fox and the other eight members of her band have just barely enough room for themselves and all the Tuesday night rehearsal essentials: drum set, mic stands, a mini fridge stocked with Red Bull, and a bottle of chardonnay. The only things on the wall are a dry erase board with a set list scrawled on it and a small poster for a band called Mass. Hysteria.

As I take a seat on a stool behind five back-up singers, Fox gets down to business: With a new drummer and just two rehearsals before the next show of their fall residency at Atwood’s Tavern in Cambridge, they’ve got a lot to cover in little time. Formalities complete, Fox leads them into “Blue Bodega.” More on that later.

When I leave about an hour or so later, the Mass. Hysteria poster makes a lot more sense. It’s a callback to Fox’s initial forays into music when she sang lead for the Brookline-based ska band as a teenager, prior to her taking a hiatus to pursue acting for several years. But it’s also something of reminder that, after being the sole female in the group and only writing two songs in the seven years they were together, she’s running the show now.

“It’s pretty close [to ideal],” Fox says about her current band roster on the phone the next day. Must have been those three additional singers she added three months ago. “In an ideal world, I’d have five singers. I was thinking, there’s no real money involved in this yet, why wouldn’t I make the sound I just wanted?”

The additional singers helped Fox evolve from her early work, which drew inspiration from Leonard Cohen, Roy Orbison, and ’60s French pop songs, to her current sound, which spikes the formula with some blues, soul and touches of gospel. But it’s clear that her singers, The Steinems (named after feminist author Gloria Steinem), provide more than just pretty harmonies.

“It was nice to have women around,” Fox admits. “It just brings so much joy to the band. I feel very grounded and rooted with them onstage behind me. And in a way they are kind of doing what a piano does at this point. They are creating a big soundscape behind the music.”

She adds: “I think I got more comfortable with my own voice over the last year, just feeling more free to really explore soul, which takes just a lot more breath and it’s a bit of a bigger sound.”

Back to “Bodega,” which seems to capture everything Fox is going for stylistically. It pulses to a rock beat, with Fox’s vibrant vocals at the epicenter of a driving rhythm section and backup harmonies. “Shake it off,” Fox sings, sounding like a street-smart version of a certain doe-eyed superstar in her current hit single.

We like this one better.

RUBY ROSE FOX W/ TIGERMAN WOAH!. ATWOOD’S TAVERN, 877 CAMBRIDGE ST., CAMBRIDGE. THU 11.6. 10pm/21+/$7. RUBYROSEFOX.COM