One of Semibreve festival's most appealing aspects is its relative modesty. 13 acts across three evenings and three venues means that it's perfectly possible to see everything on the bill and still have time to take in the wide range of talks and installations by the likes of Phil Niblock and Jorge Pandeirada. As such it makes for a relaxed end to a hectic festival season, the thoughtfulness of the line-up reflected in the quiet surroundings of the Portuguese town of Braga. However, despite the amount of events there's a lot to think and to talk about. Frances Morgan's interview with former Cluster and Harmonia member Hans-Joachim Roedelius alone brings up enough interesting ideas to last through the weekend, while the music on offer contains the variety to suggest all sorts of avenues which electronic music could explore over the coming year. Here are some of the things we learned at the 2015 Semibreve festival.

Do easy

Hans-Joachim Roedelius is every part the puckish figure of legend. His Friday night performance opens with the tinkling of a music box, before he sits down at the grand piano and with that immediately recognisable and bluntly direct style familiar from across his intimidating array of albums, starts playing a Beethoven melody. What begins as decoratively pretty soon starts spiralling this way and that, as the musicians charged with joining Roedelius - none of whom have played with the man before – bring in their contributions and he moves on to his bank of electronics at the centre of the stage. All this is held in starkly beautiful relief by the simple visuals from artist Maria Monica: coloured paper shapes, crumpled and flattened, sliding past each other with the same hasteless ease as the music. It's a lesson in restraint and accuracy. A reflection of the same values that have been noticeable throughout Roedelius' musical career. In his Saturday lunchtime talk with Frances Morgan, he reveals how his job previous to music was that of a masseur, something which involves a deep understanding of both relaxation and pressure. His set at Semibreve is a reflection of his ability to marshal both of those forces into timeless musical forms.

Klara Lewis is unbeatable right now

Tim Hecker's last minute pulling out of his show on the Sunday night has the effect of necessitating a bill reshuffle, one of the effects of which being that Klara Lewis has been upgraded to the plush surroundings of the opulent, velvety and seated Theatro Circo. Previous encounters with Lewis' brittle and fearsome sheets of static have taken place in far less salubrious surroundings, so it promises to be interesting when Lewis goes to work – head bowed over her equipment while her superb visuals tear holes in the the paintwork behind her. It's worthy of note that out of all the AV shows that propagate festivals these days, Lewis' relatively modest set-up is one of the most effective and striking. Abstracted to a still-recognisable degree, images clash with fetishised surface tensions and blaring irregular eruptions of colour in a way that seems to feed off of and back into Lewis' marshalling of the scrawl and hiss of her heavily processed found sound. There's a subtlety to her approach that renders the grey blocks of fuzz and clanking of structure against structure oddly sinuous – a kind of living and breathing evocation of concrete and clay that sets her work in sharp contrast to what was described by Steven 'Heatsick' Warwick in his talk with Frances Morgan as “Artisinal Industrial” (by which I believe was meant “another record with a picture of a fucking tower block on it”). It's an approach that yields a more nuanced and evocative record of modern existence than most in the boot-in-the-face-forever brigade would be able to communicate.

What's wrong with being 'sexy'?

Another hangover from the gory glory days of industrial culture manages to leave a sticky mark on the Saturday night, although the problem was nothing to do with the music. Indeed Vessel puts on a storming show: shirtless, headbanging, gripping a pen torch between his clenched teeth, his callous and punishing blend of EBM punch and grimacing electronics adds a much welcome dose of rock and roll hysteria to proceedings. It's an enjoyably perverse pleasure to hear such visceral and gristly music jackhammering through Theatro Circo.

No, the problems lie with Pedro Maia's accompanying visuals – specifically in their clichéd recycling of the classic industrial themes of domination and submission. It starts innocuously enough with some tits - as always, because I cannot remember the last time I saw a back projection used by a supposedly 'transgressive' artist that didn't have some tits in it. Black and white tits. Art tits. Tits hanging around in flickery, alienating looking corridors. It's like an Electric Wizard backdrop with added 'A' levels and no sense of humour. Then on we go through a parade of women wrapped in plastic sheeting, women with each other's fingers in each other's mouths, each other's shoes in each other's mouths, women crawling around on all fours in no clothes (there is admittedly a welcome break in which some geezers stand around naked in a bath tub – their bits pruriently hidden from view, because fuck knows what would happen were the audience to see a cock, eh? - and do unexpected things with an iron, but this is presented as a sort of Dad's Army-directed-by-Pasolini aside and doesn't hang about for long). I'm all for titillation, I'm even all for titillation in public spaces at otherwise demure electronic arts events, but seeing sexualised violence enacted against women for the purposes of nebulous and clichéd 'edginess' lost its charge around about the time of Mauthausen Orchestra. Vessel's punishing, eroticised racket deserves better than this.

Biff Bang Powell

Oscar Powell's music has gained a reputation for dipping its toes into the more extreme and esoteric edges of post-punk, noise and techno. Across his releases on XL and his own Diagonal imprint his formula has been used to punishing and direct effect, with curdled electronics and unexpected beats whip snaking across each other like concussed TV static. So you could be forgiven for being a bit trepidatious about witnessing the tumult of his live show, especially if it's occurring on Halloween night. But Powell surprises by providing possibly the most out-and-out fun spectacle of the entire weekend. Clad in a white t-shirt and gesticulating wildly as his furious combination of beats and noise clatters around the GNRation venue, in this sweaty context Powell's music is revealed as being surprisingly funky, with a large hip-hop influence running through it that I hadn't noticed in the records. For all its face-value 'unfriendliness' this is enjoyably gonzo - even goofy - music and perfect for dancing your drunken ass off to. It's this combination of unforgiving pummel and out-and-out fun that makes his set perfect for Halloween night and perfect for a festival as wide-ranging, challenging and enjoyable as Semibreve.