Royal Concertgebouw Orchestra / Haitink, Barbican, London

Bernard Haitink's 75th-birthday bash began at his home from home here in London, with the orchestra that was in effect his education, his apprenticeship and his passport to a big international career: the Royal Concertgebouw Orchestra of Amsterdam. That it came to him is some measure of the esteem in which he is held. Four other great orchestras will follow it here over the coming months. But it will always be first among equals.

Forty years ago, Haitink became the orchestra's youngest principal conductor ever. He is as much a part of its tradition as the great names of the past such as Willem Mengelberg and Eduard van Beinum. The many young faces in the orchestra may now suggest change, it is amazing how little its sound reflects that. One still reaches for the same words to describe its music: warm, cultured, homogeneous.

It's a Haitink kind of sound - solid, well rounded, generous. But it's interesting how temperamentally better suited it is to some composers than others. These two concerts were lessons in the relevance and importance of style as it relates to sound. We began with Debussy's La Mer. The watchword here was "blend"; warm waters and a gentle swell. The passages one remembered were those redolent of dreams: divisi cellos in the first movement; becalmed oboe and flute in the last.

But from magisterial seascape to bloody snowscape - Shostakovich's war-torn Eighth Symphony. A different world, a very different proposition. "Blend" is suddenly a dirty word. Textures are stark, delineated. It's not natural warmth you now seek but pallor. Haitink did his best to encourage the personality makeover urging his woodwind, for instance, to shrill derision in the parodistic second movement. A great first bassoon and piccolo were unlikely clowns - little and large. But the overriding impression was still very much of an orchestra unaccustomed to making ugly sounds. The gloves never really came off. The brutality of the climaxes seemed strangely unmotivated, the ensuing desolation impersonal. All very objective (and Shostakovich was never that).

But then, the following afternoon, came Mozart and Bruckner and all, plus a little bit more, was revealed. This repertoire is where this orchestra lives. Andras Schiff played Mozart's darkly operatic Piano Concerto No.20 in D Minor, his expressive hands poised over the keys for a good fifteen seconds before his first entry - hearing, feeling the music before making the sound. The sound, as one has come to expect, was cleanly, limpidly, brilliantly articulated, but it was Schiff's wide-ranging dynamics and sternly assertive left hand that gave the reading its almost sulphurous quality - like Don Giovanni himself were skulking around the next corner. The precipitous arrival of Beethoven's first movement cadenza was startlingly prophetic.

Haitink's Bruckner - the unfinished Ninth Symphony with its unprecedented crisis of faith - was magnificent. The orchestra played Shostakovich; they inhabited Bruckner. The symphony evolved. It seemed to create its own acoustics, find its own space - a universal cathedral of sound. There was even the Thomas Tallis moment in the great slow/last movement. Admiration turned to awe.