Metal Machine Trio, Royal Festival Hall, London

Jez Butterworth's must-see play, Jerusalem, ends with its central character, Johnny "Rooster" Byron, banging on a drum and calling on the spirits of the forest to defend him against approaching bulldozers, which symbolise the encroaching modern world. It is a primal, feral and stirring moment. The same could be said of the sight of a worryingly frail-looking Lou Reed banging repeatedly on a huge gong.

These days Reed generally stoops and is slow moving. He tip-toes between instruments, barely filling his expensive-looking leather jacket and jeans. But when he reaches a gong, a guitar or a timpani he can summon energy from deep within himself. As a feedback "wall of sound" lifts him up on its shoulders, for the odd brief moment you half expect Reed to start banging his fists on his chest and hollering at the sky. It is no last stand but as a two-fingered salute to conventional listening habits it is aurally offensive and bold.

The origins of Metal Machine Trio are as multi-layered as their sound. Reed will never give a straight answer, but legend has it that his original Metal Machine Music album, which was released in 1975 by RCA Records, represented a begrudging fulfilment of a contract. After hearing its guitar feedback at different speeds – and its lack of conventional songs or vocals – fans reportedly returned the album to shops, thinking there had been a mistake. Reed later claimed he "was trying to do the ultimate guitar solo". With Brian Eno's Discreet Music, which was released in the same week, Metal Machine Music became a key influence on what came to be known as ambient.

These days, it's all about improvisation. Reed is joined by the avant-garde composer Ulrich Krieger on tenor saxophone and live electronics and the Brooklyn musician Sarth Calhoun on "continuum fingerboard and live processing". For an hour and a half Krieger and Reed wander around the stage, swapping instruments, while Calhoun stays rooted to the spot, jittering his hand around in a trance-like state. Krieger indulges in sax-histrionics, practically writhing around on his back, producing free-form jazz. Reed works through power chords. Considering all that, the time goes surprisingly quickly and the cacophony is occasionally moderated by serene, contemplative moments of synthesised violin. The best bits are undoubtedly when the three musicians spur each other on to create increasingly intense levels of noise.

While the evening was not quite sold out, and the odd person walked out – presumably disappointed not to hear "Walk on the Wild Side" – there were celebrity guests to be seen, looking on with consternation or rapture. The musicians Bobby Gillespie, Warren Ellis and Kevin Shields and the artist Sue Webster were in the audience; Scott Walker was rumoured to be on the guest list.

You wouldn't want to take your kids to see them, but as a piece of theatre the Metal Machine Trio have a galling lustre. To conclude, Reed even managed to punch the air.