SCARPIA / Pioneers] O pioneers]: Meredith Oakes is swept aloft on some dynamic fades and even more masterly swells at the Barbican and the South Bank

ALTHOUGH telecommunications and recording have never been better, an orchestra's status still depends on foreign touring. It will reach the point where they're all in the sky at once, competing for cities to descend upon.

Last Wednesday brought the San Francisco Symphony as part of the London International Orchestra Season. They have a good press agent who has told the world about their Bruckner Fourth, so one went along to the Festival Hall ready to put up a bit of consumer resistance. No use: it was marvellous. Most unexpected was the absence of glitz. It was plain that their conductor, Herbert Blomstedt, had worked on the music with an inquiring, devoted intelligence that was not self-seeking.

The sound was dryish, incredibly well co-ordinated, with masterly dynamic fades and swells that fed into the sustained tension of the whole five-movement span. The brass were as supple as strings; the strings had amazing pianissimi, and a steady dark heart of resonance. The delight of those sunny, childish, upper reaches of personal faith became irresistible. There was no heavy conventional ceremoniousness; every moment of the music was agile, every moment shone.

The warm-up was a commission for the orchestra's elegant and spirited first oboist, William Bennett. John Harbison's Oboe Concerto was chirpily competent, Post-Modern, a digest of favourite pirouettes and timbres from Copland to Gershwin, Stravinsky to Gil Evans, a good vehicle but bromide.

MORE unusual and personal, though still not sufficiently so, was Robert Saxton's Cello Concerto, a London Symphony Orchestra commission premiered by Rostropovich in the last days of the Britten Festival. Any work championed by this remarkable player has a certain oomph, but Saxton had made it really tough going by reserving the more curious, interesting corkscrew rhythms for the accompaniment. The orchestral mood was routinely apocalyptic, with steady drumbeats and molten industrial showers of brass. Through this the cello strove in long note-for-note discursive spans whose lack of personality verged on the obsessive-compulsive.

FOR musical pioneering one needed to go elsewhere. St Giles Cripplegate, inside the Barbican, is a sober, resonant, undecorated, handsome church. So resonant that on Sunday, James Wood, presiding over a Microtonal Weekend that was essentially a percussion smorgasbord, issued an 'aural health warning'. Xenakis' Metaux, written for specially invented instruments along the lines of a steel band (played by the visiting Percussive Rotterdam), was dangerous. All of us sitting in the front pews were advised to go to the back, away from the first line of breaking sound-waves. There, as the piece wailed and splintered in a pointillist hailstorm, one was able to observe music- lovers sitting with their fingers in their ears so as to hear it to the best advantage.

The technical pioneering of Xenakis is matched psychologically by his determination to involve computer mathematics in the dramatic expression of awe and wonder. He is a star. Far more usual are those composers who potter amiably at the technological margins, making useful discoveries at a relatively low emotional temperature. Of the many represented in a fascinating weekend, Frank Denyer, with his murmurous, buzzing piece Confined in a Strange Garden for odd, quiet instruments from obscure parts of the world, seemed particularly skilled. Microtonality is such a huge subject. It brings together the vocal-style leanings and tweakings of flutes, strings and so on (represented notably by the distinguished guest Yoshikazu Iwamoto, who played the Japanese flute, king of all such yearning and languishing instruments); the magical irregularity of gongs; and the new technology which can synthetically divide the octave up as many ways as you like, and break one sound into a swarm of different elements.

One of my favourite pieces was one of the simplest: David Lang's Anvil Chorus, a virtuosic moto perpetuo played largely on metal bars that looked as if they'd come off a construction site. At the other extreme of portentousness was Radulescu's The Outer Time, a Homage to Alexander Calder. Gong sounds were slowed and sustained into a sonic boom that came at you through the floor and the walls. James Wood's new piece, Spirit Festival with Lamentations, featured the American quarter-tone marimba player Robert Van Sice in a feast of special effects that included oriental drum calls more blood-curdling than their Japanese prototypes.