Wandering in from a balmy September evening outside, the heat and humidity in this Hackney pub's upstairs room hits you like a smack in the face, the air immediately clinging close to your skin. It's only going to get closer. Tonight is the second of this week's two performances from Carter Tutti Void, and only their third ever live show following their debut some three-odd years ago at Mute's Short Circuit festival, later immortalised on the Transverse album. It opens, as did that gig, with the mechanised four-to-the-floor throb of a kickdrum, soft around the edges but diamond-hard at its centre, and the atmosphere presses in further still. The shared sound the trio have alighted upon is at once formidably dense and near-transparent; like a steam-powered machine at a Victorian curiosity fair, you can hear all the cogs, gears and oiled pulleys grinding away at its centre, and - crucially, at this shuddering volume - feel in your guts the points at which the friction between these pivot points becomes almost too much for the entire carefully weighted assembly to bear.

There's little concern for easing us in gently. Chris Carter jumpstarts the system with the required jolt of input energy and the machine is off and away, dragging a roomful of sweaty-browed souls along in its wake. Centre stage, he cuts a focused figure, adjusting parameters with the dedicated attention of a technician at work in a lab. Each tweak sends razor shards of noise and insectoid percussion scrabbling through the mix, all building into a dynamic, roiling, viscous groove, where individual details boil to the foreground and strafe your senses before being sucked back into the fray again. By now what previously felt machine-like has seamlessly evolved into something organic, a fleshy mass of legs, mandibles and hard exoskeleton scuttling forward like a marauding column of army ants, through which Nik Void and Cosey Fanni Tutti's guitars erupt like black smoke from a volcanic fissure.

And then, abruptly and unexpectedly, it stops, at what feels like almost an arbitrary cut-off point. The music's inexorable build temporarily halted, the crowd cheer. The trio pick up where they left off, the vortex opens once more, and the music's density continues to thicken. This stop-start pattern punctuates the set, but with music whose power lies in its feeling of being flattened by a single, gradually evolving groove, and in the absence of what you could call 'songs' (these monolithic constructions feel more like architectural diagrams than the stretched, yet still recognisably song-form compositions of Chris & Cosey or Factory Floor), they feel slightly out of place. Each pause breaks the spell, and requires the trio to work to establish it once more.

Which, in all fairness, they do with ease. Seeing Carter Tutti playing their 1980s-era pop songs as Chris & Cosey live over the last few years, what's been most striking is Chris Carter's sound design: subtle and tactile yet also tough and steely, it's capable of simultaneously caressing your skin and walloping you hard enough to leave bruises. So in their recent, technologically enhanced live versions these songs, always erotically charged and concerned with physicality, have become body music in quite a literal sense: on a good club system, their frequencies cut right to your core. Several moments tonight - especially one particularly riveting track late in the set - feel like the closest Chris and Cosey have come to crafting full-bore dancefloor music, and the results possess an ambiguity of intent and emotion that puts plenty of today's self-consciously noir-ish slow techno to shame.

Yet this isn't exactly dance music, or rather, its most intriguing characteristics point towards something freer. Unsurprisingly for a relatively young project, tonight's performance still feels embryonic - the trio's members still sound in the process of gradually feeling out their music's shape. But at its core is the three-way group dynamic; there's a palpable, visceral tension between Carter's rhythms and the wilder and more impulsive roles played by Cosey and Void, who exchange caustic riptides of guitar noise from either side of the stage. Void in particular plays a crucial role. Attacking her guitar's strings with bow and drumstick to produce sustained, fizzing drones and blasts of percussive feedback, she's locked into the groove yet also an autonomous operator - freed from the sequencer's tick that holds everything else in check, her guitars have an anarchic, exploratory feel, constantly straining but never quite managing to fully tear free of the structures surrounding them. It's the same tension that defines Factory Floor at their live best, except where the latter would often threaten to singe your hair off, here it's put to the service of something more mindful, meditative and grounded. During its best moments, tonight's performance hangs poised on the edge where group discipline crumbles and individual impulsiveness takes over; it's exciting to imagine Carter Tutti Void venturing further into this spontaneous, improvisatory sound.