In the middle of the floor in an otherwise empty King’s Cross Scala there’s a man up a ladder, adjusting a spotlight from its normal target of the stage. At the bottom of the ladder, Dan Deacon, composition graduate from the New York Conservatory of Music turned electro-prankster-maverick turned composer again, dressed in what can only really be described as sweat pants and a tatty cardigan, is arranging several synthesisers, sequencers and small boxes covered in day-glow electrical tape on a trestle table. There’s a set of cheap, mobile-disco-style traffic lights propped up behind him and, above the table, perched precariously atop a flimsy-looking tent pole, is a plastic skull that sporadically flashes a luminous Halloween green. In a few hours this whole ramshackle set-up will be surrounded by ardent fans – the only things on the Scala’s stage will be two drummers and a huge speaker stack. Behind his neon table, Deacon, still wearing the same jogging bottoms, will be conducting his latest musical communion, giving orders to his audience to kneel down as one, “like Rafiki from the Lion King was the only character in the only movie you’ve ever seen,” or dance off against one another in a huge, coordinated group hokey-cokey. Without fail, they will obey.

If this concept for a show – lights from Maplin, everything seemingly held together with gaffer tape and daisy-chained four-way power adapters, music emanating direct from the mosh pit, bouts of mass audience participation – sounds slightly unusual within modern, sanitised gig culture, not to mention fraught with potential disasters, that’s because it is. What’s stranger still is that once the gig is under way, like a far-fetched action movie that appears nonsensical on paper, something in the room makes everyone suspend disbelief for its duration and join in. The site of Deacon head-banging in unison with his front-row fans now seems an utter inevitability; any ickyness at the thought of being coerced through a round of zany dance moves is unfounded.

In short, the sense of triumph doesn’t just stem from a startlingly original, entertainingly bizarre spectacle, but also from how difficult it is to imagine something this madcap actually coming off. Then again, the same could be said of Deacon himself: here is an oddball of the highest order, wildly un-preoccupied with blending into any background socially, physically or musically, making records that are confrontational, harsh and complex, and doing so with an élan that only really makes sense once it’s witnessed.

However, if the rickety DIY aesthetic in his live performance is something that Deacon has cultivated to near perfection over the last ten years, his recorded output is going in the opposite direction: where once he was content making records called things like ‘Silly Hat Versus Eagle Hat’ that were blasts of 1,000bpm absurdist electronica, his latest album is simply and calmly called ‘America’ – and deliberately confronts all the meanings and evocations that that word conjures. Most impressively it contains a 22-minute ‘USA’ suite, inspired by his first trip outside the States in 2007 and scored subtlety, with considerable craft, for chamber orchestra (although still laced with electronic savageness). The four movements deliver melancholy and delicacy, and the result is like Fuck Buttons filtered through Aaron Copeland and Steve Reich at their most bucolic – a far cry from ‘Goose on the Loose’ and any number of his once-trademark raging bursts of white noise that sounded like armies of toddlers licking batteries.

There runs the risk of a collective groan when a once “fun” musician decides to start making “serious” music, but Deacon wears his maturity well, if slightly bashfully. In our forty-five minutes together, he talks enthusiastically about the intensity and relentlessness of his music, although never for very long: within a couple of minutes of discussing his actual recordings, he’s disappearing off on a tangent about the internet, or conspiracy theories, or the DIY scene. His favourite diversion, however, is grander than all of that and, thankfully for the patient interviewer, also the inspiration for his latest LP.

“Oh, it’s complicated!” he laughs when asked how he feels about America, and why he wanted to write an album about it. “We’re probably not on the best terms. When I first went on tour to Europe, I, like many other Americans, didn’t identify as ‘American’. The United States was an evil, Earth-destroying monster of war and bigotry, you know? But then when I got to Europe, I felt like an outsider. I was alone in foreign lands, and realised I am an American, and nothing I can do will ever change that, and that was a massive shift in consciousness for me.”

Deacon is now in full flow, gabbling but super-lucid, imploring me to listen. “It also got me to thinking that my ambivalence and apathy towards my country is almost part of the system that I hate. Like, as soon as you start realising that this is all just to make the rich people richer, you start thinking, ‘there’s nothing I can do, fuck it, I’m not a part of this bullshit system anyway, I don’t care if it falls apart.’ And then you slowly realise that holy shit, of course they want you to think that! If you don’t care about something, there’s no reason to try and better it, or save it. It’s like having a rotting shack in your back yard – you’re not going to go out and fix it unless you care about it. You’re just going to tear it down.”

Like he said, it’s complicated.

“And then I started realising that actually there are aspects of American culture that I love, and that I think are beautiful and awesome. I started thinking how much I loved travelling across the country and going from coast to coast and seeing the landscape slowly change over the course of the seasons, and that’s what inspired the music on the album.”

Indeed, a love of the dramatic American landscape is clear on ‘America’. Grand, sweeping brass and elegiac strings evoke the quintessential widescreen Western frontier that everyone from Ennio Morricone to George Gershwin has had a go at making musical in the last century or so, with the burbling, relentlessly repeating electronics offering a counterpoint of constant movement and exploration. Indeed, listening to ‘America’, is Deacon rather more fond of his country than he is of his countrymen?

“I see what you’re saying,” he answers guardedly. “But I don’t think it’s the individual people so much as the system that’s put there to control everybody. I mean, I think you’d be hard-pressed to find any American who’s like, ‘I love the government! I think the choices they make are great!’.”

It goes without saying that Deacon isn’t one of those Americans. But this month he also has the right, regardless of how American he feels, to have his voice heard on that matter in the presidential elections. Given his previously stated opinions though, it seems fair to wonder if he’ll even bother putting a cross in a box. He insists he will be: “A lot of people think voting’s a joke, but it’s important to represent your demographic. I don’t care if you vote for Daffy Duck On Acid, but it’s important that your voice is there and present. And with local issues I feel you can have direct action through voting. You can really change things on a small, local, town-county-state level – I don’t think that’s idealistic. I think it’s actual.”

And herein lays perhaps Deacon’s essence: despite his cynicism and apathy towards so much of the modern world in general and his homeland in particular, he remains upbeat, and absolutely unswervingly sure that change is possible. That sense of hope against adversity shines through in his recordings, too, albeit in quite an intangible way: half of America is instrumental, and the other half’s lyrics are virtually unintelligible. Nonetheless, the lyrics are there – and published within the album packaging – and they’re of particular note, he says, as this is the first time that he’s actually tried to make them mean something.

“I don’t like the obvious ‘this is my ideology, this is how I think’ lyrics,” he explains when asked what he was aiming for with his words. “The problem with the general modern protest song is that I’m just like, ‘oh God, shut up! I hate that I agree with you!’. I’d rather there just be that spark of an idea instead. For example, there’s this one line in ‘USA’ that goes ‘I’m not the shapes that I’m shown’, and people will be all like, ‘oh, well, of course he’s talking about his body issues and yadda yadda yadda,’ but that’s better than the lyrics being all like [at this point he starts singing in a comedy X-Factor melisma] ‘I’m a fat person in a skinny society and I feel bad for many reasons about it!’. It doesn’t have the same hit, you know?”

It should be noted, at this point, that Dan Deacon is not a slender or particularly tall man, but neither is he particularly overweight. That said, he wears comfortable clothes and has a straggly beard and unkempt hair that looks genuinely like the product of not caring, rather than a deliberate attempt at the “bed-head” look – in fact, his whole demeanour is rooted not even in anti-fashion, but in a world where fashion just doesn’t exist. Nonetheless, when I pick up on his mock confession, he’s surprisingly candid and self-lacerating.

“Of course I feel like a fat person in a skinny society, 100%,” he admits. “And I also feel ashamed because I know that to become fat you have to eat more than your body needs. I have these internal battles, and it bugs me quite a bit, but what bugs me even more is times like when the album got streamed on The Guardian, and almost every single comment was about my beard: People kept calling it a ‘hipster beard’, and I really wanted to respond by saying, ‘it grows out of my face whether I like it or not!’.”

Did it frustrate him that people didn’t want to discuss the music?

“I was pretty excited for the comments to be about the music,” he admits, “but at the same time I just acknowledged that The Guardian is a mainstream publication, so of course it’s going to be more interested in fashion than experimental music. The thing is, I don’t harp on about these things but they’re things that I think about a lot – so in the ‘USA’ suite I was trying to wrap them all up and gather everything that is constructing my American identity.”

At that point, for the first time since we began talking, there’s a silence that suggests Deacon feels he’s said too much. “Okay!” he beams with an avuncular, if slightly nervous chuckle. “Let’s talk about something else!”

Back at the Scala, Deacon’s trestle table is now encircled by eager fans, waiting for the fat person in a skinny society to come and make everyone do a bit of exercise. He arrives at his station chaotically, bumbling through the crowd, and ten minutes later he still hasn’t played a note of music. Not that it matters: he has got the crowd onside by telling bizarre, stream-of-consciousness jokes and making them all point at the ceiling while chanting “omm”, kneeling first on one knee then on both and “imagining the saddest you’ve ever felt in your life.”

Then at the touch of a fluorescent orange button he’s away, and ‘Guilford Avenue Bridge’, the opening track from ‘America’, gallops into the distance while the pair of drummers behind him try to hang on, like cartoon cowboys on a bucking bronco. There then follows a section where Deacon creates a circle in the crowd so the more exhibitionist among it can dance off against each other. He also arranges a human tunnel that snakes around the entire building, up staircases and back into the main room. He parts the crowd down the middle and nominates one fan from each half to lead that section in what resembles the world’s most inadequate but joyously daft workout video. And then, once events have grown so surreal that you believe magic could happen, it seems like it does.

Deacon’s party piece on this tour is the interactive Dan Deacon Live Show app – presumably the logical progression for a performer whose act is so inexorability linked to his public – which, once running, listens and responds to the music. “We send out a calibration tone, like an old modem sound,” he explains before the show, “and the app analyses it and then knows to trigger the lighting sequence for a song, or to turn the phone this colour or do that sequence. Since we’re just starting out with it, it’s interesting to see how it interacts – it’ll either work well, or it won’t work at all.”

As it turns out, the former possibility is an understatement. Midway through the show, Deacon sheepishly requests that everyone who has downloaded the app get their phones out (“The main thing I’m having a hard time with at the moment,” he confesses, “is how to make it not awkward to say ‘okay now take out your phone! Open up the app!’ – it hasn’t exactly been integrated into the lexicon of punk rock yet”), and hold them in the air. The aforementioned calibration tone rings out, and seconds later, Deacon and his drummers are pounding through ‘True Thrush’ while 200-odd screens dotted around the Scala change colour, in unison, to the beat. When the chorus kicks in, the flash on the back of each unit begins to pulse too. Some wag down the front has even brought an iPad, which obediently dances the same as its brothers and sisters until its comparatively giant screen starts to feel like the leader of this army of devices, cheerleading its way to some handset heaven. “It needs a critical mass of phones, or else it’s just weird,” warns Deacon earlier. “But when we reach a certain number, it looks awesome.”

He’s not wrong. Not only does it look awesome, but, in the context of so much oddness, the sight of mobile phones taking on lives of their own and dancing alongside their owners feels genuinely fantastical, even for Deacon, whose reputation for memorably unconventional live shows has preceded him for years, this spectacle is extraordinary.

For all the jaw-dropping magic, though, his final piece of crowd interaction is perhaps the most symbolic. Each audience member is asked to close their eyes and put their hands on the head of the person in front of them. He then asks everyone to take a step to their left, and all of a sudden the crowd is rotating serenely around the room as one, like the free-spinning front wheel of an upturned bicycle, where all the spokes point towards Deacon. As the audience perform as instructed, Deacon sets off a tinkling, graceful drone on another primary-coloured gizmo and points out what they’re doing: “Feel how the actions of each one of you is directly affecting another person?” he asks. “And that by cooperating with one another in doing something really simple you’re making everything look beautiful? And how if any one of you stopped it would all have to stop? Well, I want you to take that thought away with you tonight.”

Ugh, you may think, how schmaltzy; you could almost imagine Jerry Springer ending another of his perversely moralistic tabloid talk shows with something like that, or a cynical presidential candidate using the speech as a more poetic version of “we’re all in this together”. Ugh, you may also think, how American – and if so, that’s perhaps Deacon’s greatest trick yet, given his recent preoccupations. But while it could be all of those things, the most overriding feeling in the room is, simply, how Deacon.