Phish and crew bustle about Shoreline Amphitheater’s backstage area in Mountain View, Calif., a sprawling patio where memories linger of raging parties from bygone tours.

Hours before a recent show, the scene is markedly different. Voices and footsteps carry across the expanse of empty picnic tables. A baby stroller clatters across wooden planks. As afternoon slants into evening, a ruckus finally kicks up: A pingpong game between Trey Anastasio and his teenage daughter.

“Fifteen-love,” says the Phish guitarist.

To understand why the touring jam band juggernaut broke up for nearly four years – only to resurface with a stunning depth of clarity in live performance, its strongest album yet and an ambitious festival last weekend – measure this family-centered serenity against the colossal traveling party they left behind.

“We used to have a lot of people hanging around, and it was a crazy scene backstage – crazy,” Anastasio says. “I remember being here, a number of times, and you couldn’t get through. There were literally hundreds of people, all the time. Everywhere.”

The scene was a symptom of a lifestyle the members of Phish knew they couldn’t sustain. So after 20 years on the road together, they staged a farewell blowout in Coventry, Vt., in 2004, their seventh massive festival. It began with a freakish downpour and ended with the emotionally shattered band struggling to say goodbye.

More than four years after the split, Phish roared back to life in March with a three-night reunion stint in Hampton, Va., followed with a summer tour of bootleg-worthy shows.

Their new album, “Joy,” released in September, was critically lauded for its musical and lyrical maturity and refreshed, live-show-inspired sound.

A fall tour is in the works.

While it would seem Phish could risk relapse into old habits, the band agreed on the changes that have made their rebirth possible. The number of dates the band plays has been scaled back, and the members have kept their pact to put families first, even on the road.

That means lots of kids backstage – seven in the Phish family so far, most of them on tour – and not so much the hundreds of hangers-on who had snowballed out of control through the years.

As Anastasio likes to point out, there were 3,500 people on the guest list at their “farewell” show in 2004. At the reunion show this year, there were 10 – “and seven of them were under the age of 13.”

“It’s just a very nice vibe,” bassist Mike Gordon says. “And the music has been feeling really good as a result. I had no idea whether removing the party element would make it sterile or something – but the opposite happened, where it feels like we have extra consciousness left over to jam harder. It feels like a great era – it’s the beginning of the rest, like we’re in it for the long haul again.”

Keyboardist Page McConnell says he’d always figured that Phish wouldn’t regroup, and spent his off-time well to that end: His serious study of classical piano and a solo album gave the band more balance through which to hear complex interplay.

“I thought, well, I don’t want to come back a little bit staler – I’d like to come back better,” McConnell says. “But I really feel it from all of us; the way we’re listening to each other, and the way we’re communicating, we really make each other sound good.”

Working with a vocal coach has also helped Anastasio and Gordon: On “Joy,” the quirky, isn’t-this-silly singing style has been all but abandoned. It’s probably no coincidence that “Billy Breathes,” another cherished Phish studio recording from 1996, also was produced by Steve Lillywhite.

“I told them, ‘Look – this record is your first in a few years, you’re all in a good space … you just need to be you,’ ” he recalls. “I really felt like this was a new band. They were very relaxed, and I think one of the reasons was, they have these memories of the ‘Billy Breathes’ sessions, of me just coming in and taking a great weight off their shoulders.”

Whatever the reason, everything about Phish feels lighter this time around.

The most pressure for Phish was pulling off their Halloween “costume” surprise, a tradition of covering a classic album by another artist on Halloween night (Anastasio was understandably cagey about his choice – but “Thriller” was notably still in the running, according to a process-of-elimination interactive on the band’s Web site.)

Anastasio is just thrilled that Phish is having more fun nowadays.

“It is more fun. It’s so much more fun. And it’s hard to believe that, because it was really fun for quite some time. But …. it’s fun to let all go, and just kind of ride the wave again.”