CLASSICAL MUSIC / Redeemed by lemon juice

THERE have always been soft options in new music - a Howard Blake for every Harrison Birtwistle - and they have usually found an audience, but not a serious one. The challenge of the new has been the challenge of complexity - until fairly recently when a double-front assault of American minimalists (John Adams) and European spiritualists (Arvo Part and John Tavener) has encouraged the idea that maybe there is challenge in simplicity.

This is the argument of the Vale of Glamorgan Festival, an evangelising event devoted to new music at the 'soft' end of the market and accordingly attracting larger, broader audiences than you would find at Huddersfield or (in former days) the Almeida. It runs from the St Donat's Arts Centre and manages to get big names in residence - including, this year, Tavener, Part and Gavin Bryars who have been circulating the country churches and other, idyllic, South Wales venues: cult figures one and all, with their respective followers in tow.

The performances were not as remarkable as the locations or the turnouts. The Hilliard Ensemble at Ewenny Priory were off form, and the City of London Sinfonia at St Donat's, with Steven Isserlis, struggled through an evening that died in spirit mid-way. But in each case the festival had booked what ought to have been the best performers for the repertory. The Hilliard are Arvo Part. They have the measure of his formulaic vocal style as almost no other group does. And since the runaway success of The Protecting Veil the cellist Steven Isserlis is Tavener - which he continues to play with a mix of passionate intensity and high camp, in the spirit of the music's ecclesiastical tradition.

The lesson of Glamorgan, though - apart from wearing thermal underwear to concerts in damp churches - was that simplicity is only challenging when every move in the score is made with conviction. Part and Tavener succeed because however unadorned, unvirtuosic and repetitive, their music carries a sense of the inevitable and the charge of absolute belief. There were other scores in the festival - by Jeffrey Lewis and Gavin Bryars - that failed because they had neither.

But Bryars at least is a colourful figure who has emerged into a contemplative present from a crazily experimental past. It was Bryars (a disciple of John Cage) who founded the infamous Portsmouth Sinfonia, the only orchestra in the world to admit that it recruited players for their inability to play. You wouldn't detect any of this from the cool, spare Cadman Requiem, written for the Hilliard in memory of a friend who died in the Lockerbie air crash, but there is a vestigial energy in the writing that sustains it through its half-hour length. The colouring is sober - it's a requiem after all - but with a sharpness that's occasionally like squirting lemon juice into your ear. I liked it.

Non-event of the week, and another damp one, was Nigel Kennedy's open-air concert at Edinburgh Castle on Wednesday. It was advertised as the Beethoven Violin Concerto, which would have been interesting as his recording of it is about to come out. But I should have been warned by the ticket, which read 'Gates open 7.15, supporting artist 8pm' and no mention of a conductor. At 8.30 stage hands were still testing the sound system. At 8.45 things were nearly starting when Nige told us he was going off to change his clothes. At 9.00 he was back and hacking his way through bits of amplified Vivaldi with the savoir-faire of a drunk in charge of a machete while a remnant of the BBC Scottish Symphony Orchestra tagged along. Meanwhile, a voice on the tannoy announced that due to bad weather the Beethoven would not be played 'in full form'. If at all; at which point I left. I never found out who the supporting artist was meant to be, or the conductor. There were no programmes. So much for popular communication.

A far better example of that came from the Canadian period performers Tafelmusik at the late-night Prom on Tuesday. I had heard a lot about the accomplishment of this band - mostly from their record company, so I didn't believe it and was duly dumbfounded (not to say uplifted) by the quality of their playing. A potentially unremarkable programme of Telemann, Boccherini and Biber burst spectacularly into life with a fastidious particularity of detail, a finesse of tone and an exhilarating levity of spirit that you rarely hear in period bands. There was no conductor, but strong direction from the leader Jeanne Lamon and an immaculately disciplined ensemble sense that carried through to a touch of platform theatre in Biber's programmatic suite Battalia. This proved to be a bizarrely prescient score that overlays conflicting melodies and uses a 'prepared' double bass (with paper wedged under the strings) 250 years or more before Charles Ives and John Cage thought of it.

On Thursday Opera Factory revived Yan Tan Tethera, Harrison Birtwistle's opera about folk- magic, counting sheep and the triumph of good over evil, which was first seen at the same venue, the QEH, in 1986. Since then the set and lights have been re-constructed and the lead roles of two shepherds have passed to Geoffrey Dolton and Patrick Donnelly, who are vocally strong but not as focused as their predecessors. Mark Wigglesworth conducts the orchestra, half-hidden behind a gauze, and beautifully shapes the slow-moving iridescence of Birtwistle's orchestral writing - the most attractive quality in the score. The composer calls it a 'mechanical pastoral', and it functions like the revolving mechanism of a clock - marked in the foreground by sheep-counting routines and the ritual repetition of vocal motifs, but sustained in the background by the slowly shifting processes of the orchestra. The foreground repetition grates a little with a faux navete intended to touch depths it doesn't, but the background is alluring and intriguing, especially when it accompanies the cumulative bleat of the sheep-chorus. There you do feel the mysterious order of a world in motion as the seasons turn, the years pass, and Birtwistle settles into one of his thematic comfort zones - revisited within the scale of this 90-minute chamber opera as effectively as in his biggest stage works.

'Yan Tan Tethera' continues 7, 8, 11, 12 Sept (071-928 8800).