SINGER KT Tunstall is probably used to people being rendered speechless in her company. I am recounting my first reaction to her dazzling Golden State EP – and, more specifically, its kick-the-door-down opener Evil Eye.

“I was like, ‘Oh. Good god. Whoo!’” While far from sophisticated, it’s an indication of the exuberance of these three tracks, which come with a thumping remix of Evil Eye by warped popmen Django Django.

“That is the best reaction to anything I’ve ever done,” laughs Tunstall down the phone from Kalamazoo, Michigan.

“I didn’t know there was a place called Kalamazoo,” she says. “There is – and we’re playing there tonight.”

She’s just played Milwaukee’s Summerfest (“permanent structures and no mud”) following a triumphal set a week previously at Glastonbury (“mud Mordor, but still incredible”). Rather than revisit past victories, those sets comprised at least 50 per cent new material – an intimidating prospect, were these anything less than hard-wearing, festival-sized slabs. Whether it’s the whipsmart Evil Eye, All or Nothing’s windswept rattle or the glam sizzle of The Healer – a track which features R2D2 (more on him later) – to say this EP augurs well for forthcoming album KIN, is more than reasonable. Put it this way, if it’s a duffer that rather scratched copy of 2004’s Eye To The Telescope – a record Tunstall describes as her fifth’s “spiritual predecessor” – is going in the toaster.

“A lot of the new stuff feels similar to some of the early stuff I put out,”she says of KIN, out on September 9. “It’s big, wide, uptempo with lots of backing vocals and huge pop songs.”

They also twinkle with a celebratory sense of newfound confidence and purpose. They’re like an HD version of Overglazed, the declamatory opener to The Breeders’ 2008 comeback album Mountain Battles, a track which evoked the glorious sight of Kim Deal raising her guitar and hollering from a boulder: “I’ve got my mojo back and here it is!”

Now a resident of California, perhaps she’s even done this dodging the snakes and coyotes while hitchhiking in Topanga Canyon. And she’d be entitled to that. Because it’s remarkable that we’re chatting about a new KT Tunstall record at all, never mind one so different to 2013’s Invisible Empire/Crescent Moon.

Written shortly after the death of her father (a physics lecturer at St Andrews University to whom the “Telescope” of her debut refers) and the end of her marriage to decade-long partner Luke Bullen), that album was stripped-down, sombre and echoing with loss.

After months of touring those songs, Tunstall was hollowed out. Recent events and over a decade on the recording-touring treadmill had left her feeling she’d come to the end of the road.

“I felt very burnt out after that tour,” she says. “I thought that I didn’t want to tour any more. I felt really disconnected from making music and touring.

“I really thought I was done with the whole thing.”

A change was vital. Then based in London, Tunstall sold up and bought a small place in LA’s Venice Beach. The intention was to rest, recuperate and do what she had wanted to do for a long time – enrol on the Sundance Institute’s elite Film Composers Lab. It was a successful transition, with Tunstall going on to write or co-write songs for films including Disney’s Tinker Bell and the Legend of the NeverBeast and Million Dollar Arm and soundtracks to Winter’s Tale and About Ray.

Nourished by the professional do-nothing culture of her new surrounds (“there’s palm trees and humming birds in my garden”), driving around the LA sprawl in her electric car (“like driving a spaceship with an amazing soundsystem”) or heading over the mountains to meet musician friends in nearby Silverlake, she found herself listening to Laurel Canyon classics such as Fleetwood Mac and Neil Young as well as to modern psychedelics Tame Impala, Django Django and Devendra Bernhardt. When motivation hit to write a new record, it was not through conscious choice.

“It was such a surprise, honestly,” she says. “I was starting to get to know LA, and it’s incredibly wild. You can drive for just 20 minutes and you’ll be somewhere with canyons and big open spaces. Driving through those canyon roads at night – I had watched Mulholland Drive [David Lynch’s typically unsettling, psycho-erotic masterpiece] when I went out there – you really feel you are somewhere where you could get lost.”

Those big, widescreen choruses and that more complex, kaleidoscopic undertow – elements both in evidence on current single Maybe That’s A Good Thing – had been fusing in Tunstall’s mind, whether she had been aware of it or not.

“I love that the mind and the spirit are often at odds with each other, and certainly with music the subconscious is in control,” she says. “So when I found myself writing these big, muscular pop songs. I thought: ‘I can’t ignore this. This is new.’ I felt I hadn’t been writing songs like that for a long time. So I didn’t ignore it – I went with it.”

Tunstall recorded KIN with Tony Hoffer, whom she’d admired for his work with her favourite artist, Beck.

“He’s such a mischievous, fun, creative force,” she says of Hoffer. “He’s great at shaping songs which are still going to get played on the radio but at the same time, he has a really experimental angle on things – and a studio of fantastic old analogue synthesizers. Including the one that made the voice of R2D2, which is on The Healer. Listen out for R2D2 – he’s on there. I should be like a rapper and have him ‘featuring’ on that song.”

More recognisably humanoid collaborators on KIN include Django Django’s Dave Maclean, James Bay, who duets with her on Two Way, former Ash guitarist Charlotte Hatherley, and Beck’s father David Campbell who composed the string arrangements for the title track. Tunstall played a lot of the bass and keyboards herself, a reflection of the zesty exuberance KIN shimmers with.

“When I was making that last record, that was when everything was hitting the fan,” she says. “When you get to a point in your life where everything has gone tits up, you can muddle along and pretend that everything is OK when it’s not. One of the songs on the album is called Everything Has It’s Shape.

“The chorus says: ‘Pull it apart and put it back together how you want it.’ That is exactly how I felt. I thought: ‘All right. I’m not going to just try and fudge this. Let’s just start again.”

That reboot involved a period of intense reflection.

“I really looked at myself. Some of it was very hard. Because I thought: ‘If someone takes away my guitar, takes away my voice, takes away my amp, I don’t know who I am any more. Because all I’ve been doing for so long is just focusing on music. No matter what job you’re doing, if you don’t have your identity outside of it, it’s a real disability to you. You’ve got to know who you are away from it, to be able to have relationships with other people, and know what’s good for yourself, instead of always putting the work first.”

She continues: “There was a point after the first record, with the second record just about to come out, there was a very real possibility that the shows could go into arenas. We did a couple but I was just terrified. That had never been part of my master plan. We were playing sell-out shows to six, seven thousand people. I think it totally freaked me out. And coming through the situation and getting to know myself, I am finding that I am absolutely ready to be a woman, ready to be a grown-up. I feel a confidence I’ve never had before.”

As the title of one of KIN’s tracks puts it, It Took Me So Long To Get Here, But Here I Am. Maybe that’s what she shouted over those volcanic Californian fields. She should.

KIN is released on September 9

KT plays a 10-date tour of Scotland in August, including Ullapool (15), Stornoway (16), Wick (19), Forres (20), Banchory (22), Shetland (23), Orkney (24), Inverness (26), Aberdeen (27) and Perth (28). A UK tour follows in autumn, including Dumfermline (Oct 28)