MUSIC / Animal, vegetable, minimal: Robert Maycock on the weekend's Prom concerts, at the Albert Hall and on Radio 3

THE DANGER in putting on a John Adams retrospective is that it brings back the hopes of 10 years ago. Among rising composers then, he seemed to have found a way out of the cul-de-sac of contemporary music by giving the open, repetitive tradition of Reich and Glass a dimension of energy and growth more usually found among the European avant-garde. But somewhere along the way, the freshness and excitement has gone out of the writing.

His first opera, Nixon in China, balanced between irony and sentiment, now sounds like the turning-point. Friday's late-night Prom, brilliantly played by the London Sinfonietta with Adams conducting, was dominated by two scores from the early Eighties. Shaker Loops pulses with quiet animation and little figures that rotate slowly like mobiles; an unexpected, polyorgasmic upheaval leaves a sense of poetic transformation. The magnificent, outrageous wit and all-round vision of Grand Pianola Music go further in their daring and delight. This piece still sounds in the line of great American originals, fusing a huge range of vernacular and artistic references into a synthesis that Charles Ives would surely have acknowledged.

Eros Piano, from 1989, sets more of a puzzle with its sensuous chords and puritanical scoring. There are briefly impulsive gestures, though even the solo piano part (a confident Paul Crossley here) never gets carried away. The music is not as loose and sprawling as Grand Pianola Music, and the shape is like a more rationalised, and at the same time more nostalgic and indulgent version of Takemitsu's forms, the ones that he compares to the experience of a formal garden: a short stroll around the Tokyo Garden Night Club, maybe.

But this is Adams in disguise. The references, the conscious romanticism, have now taken the lead, and the positive, American spirit of the earlier music has faded. It was salutary to hear, the following night, a new piece by Toru Takemitsu in the BBC Welsh Symphony Orchestra's Prom, finely played (as heard on Radio 3) under Tadaaki Otaka. This was Fantasma / Cosmos, a BBC commission first performed a year ago and subsequently toured, here receiving its London premiere.

With an almost constant solo clarinet part (Richard Stoltzmann, alert and eloquent), it delivers a more continuous stream of melody than much of Takemitsu's music. But it is utterly typical in its fluctuating pulse, its gentle rise and fall of harmonic intensity - rarely assertive, never hurried, and stopping punctually without fuss. There is no sign here of a culture that has lost its way; just a thing of beauty in itself, another complete utterance from a composer fortunate enough to reach maturity knowing exactly what he wanted to say and how to say it.

Friday's early Prom was like an old-fashioned Saturday, packed with real or 'exotic' Spanish music and delivered with straightforward panache by the BBC Concert Orchestra and Barry Wordsworth. Kathryn Stott played an energetic but rhythmically rigid piano solo in Falla's Nights in the Gardens of Spain. The most ravishing few minutes belonged to Granados, as Judith Howarth sang 'The Maiden and the Nightingale' and the orchestra relished its languid lines with her.

The novelty was a short vocal and choral suite that Christopher Palmer has made from Walton's music for a BBC radio play of half a century ago, Christopher Columbus by Louis MacNeice. Arthur Davies, tenor, and the BBC Singers joined Howarth and the orchestra. Whatever attitudes the play as a whole may have struck, the words that Walton set tell a story of conquest and national expansion - an ironic foil to the uncertainties of the later concert.

It includes a triumphalist chorus with some stupendously empty fanfares tacked on, a simple and fetching song, and a lively 'Gloria' with touches of the real Walton in Belshazzar-style harmony and a favourite phrase straight out of Hindemith: engaging enough, but short of substance given the large forces involved, and anyway paling in Friday's starry company, completed by Rimsky-Korsakov, Chabrier and Ravel.