Takacs Quartet/Muzsikas, Queen Elizabeth Hall, London <!-- none onestar twostar threestar fourstar fivestar -->

This encounter between two institutions of Hungarian music, one folk and one classical, has entertained American audiences for several seasons. It provokes plenty of thought in the process. Half of Europe's classical music, from Russian orchestral to Italian opera, has conscious sources in the local vernacular.

Bela Bartok and his compatriot Zoltan Kodaly must have been the most thorough of all. Bartok was determinedly scientific about the way he worked. Beyond using folk tunes as source material, he trekked around Hungary to hear the way rural musicians performed, so that the expressive and rhythmic features and the way instruments worked together could all go into his personal brew.

When he made his field recordings, he was more concerned about refreshing creative impulses than preserving tradition. Yet, as in England, there has been a spin-off in the subsequent folk revival. Groups such as Muzsikas, going since 1973, can hear the way it was done a century ago. One feature of this concert was to play excerpts from Bartok's collection, which validated the singing and playing styles as clearly as you could wish. Muzsikas, joined by the folk diva Marta Sebestyen, started with a set of songs and dances. The regular phrases, the duelling violins over rock-steady, basic accompaniment by three-string viola and bass, sounded more like what you hear in Kodaly's music than memories of Bartok.

When the Takacs followed with Bartok's String Quartet No 4, the first response was to notice how different it all was. The quartet's density, constant development, shifting pulse and sometimes violent nature all came from somewhere else. But there were still melodic patterns and bowing styles. Muzsikas played numbers of their own between the movements. And the later parts of the quartet echoed them intriguingly.

For the audience, the second half became easier as Bartok used entire folk tunes in his violin duos, played here by one member of each group. His Rumanian Folk Dances came in an arrangement by Arthur Willner which already put back some of the band style, even before the groups started taking turns to play them in their own way.

The conclusion, with both joining together, was probably the opposite of what Bartok meant when he constructed art music from folk sources - but this gesture of sharing made a thrilling climax.