'DJing is hard, definitely much harder than I thought it would be' - Zac Efron
Leaning forward and gesturing excitedly, his sparkling blue eyes twinkling, Zac Efron is talking about "pushing buttons and fiddling knobs".
But if you think the former High School Musical star is shaking off his clean-cut image and getting a bit naughty, you'd be mistaken.
The 27-year-old actor acquired a few tricks of the music-making trade to portray an aspiring DJ in his new film, We Are Your Friends, and he's keen to show off his new-found knowledge.
"I have DJed before. I haven't done it properly, I've had a lot of help," he says.
"There's definitely a lot of buttons and a lot of knobs, but once you get the hang of it and you spend enough time on that deck, you're going to get a kick out of it.
"I can do it as long as there's somebody there, watching over my shoulder.
"I would say I'm proficient at it, but by no means am I going to be headlining any wrap parties or anything like that. I cannot produce anything but I can play a little set - we are all great iPhone DJs."
California-born Efron trained with Swedish DJ Alesso and Los Angeles-based DJ and producer Jason Stewart, known as Them Jeans.
Taking a sip of green juice, he says: "DJing is hard, definitely much harder than I thought it would be. It's truly an art form.
"I got decks so I could practise at home. Put away the video games and just spin. It was probably pretty annoying for my neighbours, but luckily I have cool neighbours."
His role in We Are Your Friends marks a bit of a departure for the actor, who shot to worldwide fame through Disney's High School Musical in 2006.
The movie, which also starred his then-girlfriend Vanessa Hudgens, became a huge hit, spawning two sequels, a concert tour, a stage adaptation and a reality TV show.
Since then, he has starred in romantic dramas The Lucky One and New Year's Eve, gritty thriller The Paperboy and comedies Bad Neighbours and That Awkward Moment.
This time, his chiselled good looks and hunky physique put him at a slight disadvantage for the part in Max Joseph's directorial debut.
The director, better recognised as Nev Schulman's sidekick in Catfish: The TV Show, has admitted: "When I first met Zac, he was big and buff from doing Bad Neighbours. I explained to him that most DJs don't eat well and spend all night long at their computers, not sleeping.
"And they don't have perfect tans because they're not out in the sun."
So sport-lover Efron, who is dating model Sami Miro, shed almost 20lbs before filming started in June last year.
Today, the star looks like he's in pretty good shape, although his biceps are hidden under a baggy checked shirt and his toned legs concealed in black skinny jeans.
"It was fun to go backwards and play a DJ and more skinny, svelte guy," he says.
"Max and I talked about the weight loss early on. I guess to be more authentic I was running a lot, so I just let it happen naturally."
Efron and Joseph met for the first time during the casting process and hit it off immediately, even enjoying 'date nights' at Efron's favourite sushi restaurant in LA's San Fernando Valley.
"I hadn't seen Catfish. I'm stoked to say that I became best friends with Max before I knew anything about Catfish, so it was pure Max that I fell in love with, director Max, not Catfish Max," says Efron.
We Are Your Friends follows his character, Cole, who is on a quest to find the one dance track that will give him a hit, which leads him to question his life and friendships along the way.
He finds a mentor in the more experienced but troubled DJ James Reed, played by Wes Bentley, until he falls for his younger girlfriend, Sophie (Emily Ratajkowski, from the infamous Blurred Lines music video).
"This has been one of the best experiences of my life," Efron says. "From the very first time I read the script, I related to it on a personal level.
"This movie is really for our generation - it's a combination of the music, the story, the coming-of-age elements. It's really relevant to what it's like to be a young person right now in this world, trying to find his way.
"I knew each of these guys in this movie. It felt like it distinctly represented a group of my friends and tapped into my own journey, a chapter of my life.
"I was blown away by the characters and, of course, Max's belief in the project."
While they filmed at parties and raves set up around Las Vegas and Los Angeles, the stars were too busy to enjoy any bonding nights out.
Efron has been sober since 2013, when he entered rehab to seek treatment for alcoholism and substance abuse.
Although he refrains from revealing the contents of his playlists, he admits music is a big part of his own life.
"It's really a uniting force, and a DJ is the person who is at the helm of that, which is really cool," he says.
"We're definitely all music people. Somebody was always blasting music in our base camp.
"Music is made to bring people together, and this movie speaks to our generation. This is our music, it comes from us.
"We can create it and maybe we can change the world in some small way, and that's really exciting."
Efron is now back in full gym work-out mode, in preparation for reprising his role as Teddy Sanders in the Bad Neighbours sequel, which is due out next year.
Beefing up will come in handy when he starts filming for the planned Baywatch movie too, alongside Dwayne 'The Rock' Johnson.
"I've got to out-swim The Rock," Efron says, grinning. "I'm very excited."
We Are Your Friends is in cinemas now