Alt-J’s future remains uncertain after bassist Gwil Sainsbury’s exit

Though Alt-J seems to be on steady footing with a recently released album that comes on the heels of the Mercury Prize-winning 2012 debut “An Awesome Wave,” keyboardist Gus Unger-Hamilton remains uncertain about the future.

“We’re standing on the precipice of we don’t know what,” he said.

Though the British band’s name — taken from an old Mac keyboard shortcut for the delta symbol — indicates a comfort with uncertainty from a mathematical perspective, the band had to deal with an unexpected change heading into the recording sessions for “This Is All Yours,” which was released Sept. 23. Bassist Gwil Sainsbury left the band in January.

“He wasn’t happy being on tour,” said Unger-Hamilton. “I think we sort of thought, ‘I’m surprised that you’re leaving, and I’m shocked … and I’m sad that you’re leaving,’ but I do kind of know why without asking him.’”

Years before Alt-J performed on festival stages that included Bonnaroo, Coachella and Glastonbury, the band’s members were simply four students seeking compatible classmates at England’s Leeds University in 2008.

“When [lead singer Joe Newman] came to arts school, he wanted to meet like-minded people,” said Unger-Hamilton, who lived in the same building as Newman. “He sent some songs to Gwil, who used to play guitar with us, and got me involved and [drummer] Thom [Green] involved and figured out the people he wanted to know.”

Alt-J, who play the Greek Theatre on Oct. 20 and Pomona’s Fox Theater the following night, decided not to replace Sainsbury with a new full-time member. Instead, a touring bassist, Cameron Knight, will join the group on the road.

“We’ve shared the memory of the history of the band together. We’ve built it up from its very foundation,” said Unger-Hamilton. “So I suppose in a sense it wouldn’t make sense to bring somebody new into the band. We can do it without [Sainsbury].”

Alt-J’s sophomore album isn’t a drastic change from its predecessor. Both records are precisely compiled with a peculiar mix of dark gritty bass, light-pitched folk riffs and Newman’s warm crooning.

“While I love [‘An Awesome Wave’], we were a band that quite literally was like, ‘Can we do this? Are we allowed to make records that sound like this?’” Unger-Hamilton added. “I think ‘This Is All Yours’ is a more self-confident record.

“I think that Gwil’s departure brought us closer together. It was almost a bit of a boost for us to knuckle down and keep working and not let anything change the music we make.”

The band also picks up where it left off, recording a second part of the “An Awesome Wave” track “Bloodflood.” Like its predecessor, “Bloodflood Pt. II” commences gradually, with accompanying instruments chiming in softly as the song moves forward.

“Joe is a big fan with referencing things and referencing our own work,” said Unger-Hamilton. “I think it’s kind of in the spirit of, ‘This is who we were, then this is who we are, this is where we come from.’ Makes your entire output as an artist more coherent, giving it kind of a narrative sense.”

Alt-J also hasn’t shied away from adding fresh twists to that narrative. One new track, “Hunger of the Pine,” features a sample of the Miley Cyrus song “4x4” (Cyrus is also a fan — part of Alt-J’s “Fitzpleasure” was used during a video piece played during her Bangerz tour).

“I think it’s nice to have collaborations,” Unger-Hamilton said. “If we think someone can do something better than us, then we should get them to do it instead of trying to do it ourselves. That’s definitely a big part of Miley.”

Despite how strongly Alt-J’s members feel about their efforts to fend off lineup changes and a sophomore slump with “This Is All Yours,” Unger-Hamilton acknowledges that success, as well as the band’s future, are far from guaranteed.

“We’re well aware of our career and that the industry that we’re in can be very ephemeral,” he said. “It can be here one day and gone the next.”

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