Another response to the question might be: 'What type of string quartet?' Pioneered by the Kronos and widely imitated, a new breed has appeared in the last two decades, drawing on the resources of electronics and minimalism to exploit the atmospheric appeal of four solo strings playing in just intonation. The popularity of its concert manifestations notwithstanding, the real domain of this kind of music is private listening and the world of the recording studios. In spirit and technique, it is far removed from the classical view of the string quartet as the pinnacle of living, breathing chamber music.
The other type of quartet music, represented today by such composers as Alexander Goehr and Elliott Carter, continues to draw inspiration from the standard repertoire. Instead of creating a new ghetto of their own, works of this kind respond to placement in programmes emphasising continuity. Thus on Sunday, in the second of the Bingham Quartet's two concerts, a whole new range of feeling was exposed by the quotation, in the finale of Goehr's Third Quartet, of the Heiliger Dankgesang motif from Beethoven's A minor quartet, Op 132 - a resonance amplified by the ensemble's choice of the expansive E flat quartet, Op 127, rather than the tensile A minor, for the second half.
Casting back and forth between the not-so-ancient and the modern, the programme also revealed a fascinating difference in composers' uses of pizzicato effects. These were pioneered by Bartok, whose Second Quartet the Binghams played somewhat unevenly at the previous Saturday's recital. It was intriguing to compare that example with Goehr's employment of similar resources, not only in the Third Quartet, with snap pizzicato in the first movement dramatising the arrival of the slowed-down recapitulation, but also, alongside the Bartok on Saturday, in Goehr's own Second Quartet, dating from 1967.
Contemporary with his first major theatrical works, the opera Arden Must Die and the music theatre Triptych, the Second Quartet shares a similar urgency of language in the concrete presence of its gestures and the thread of tension binding all three movements together. In both the Goehr pieces, the Binghams chose relaxed tempi, allowing the semiquaver passages in the Third Quartet to speak with precision, and emphasising the obvious attention to detail that had gone into these meticulous performances. Another bonus was to stress the quicksilver changes of mood within these quartets, involving the seemingly inevitable modulations of feeling encompassed by an overall formal unity that is the essence of the classical manner - and therefore of the quartet medium in particular.
Offering the two quartets of Op 77 over successive weeks, the ensemble showed that nobody did this better than the father of the form, Joseph Haydn. The G major had poise and elegance; but the outstanding performance was of the second of the pair, the F major (Haydn's last quartet), on Sunday. The unruly contours of the Minuet complemented the gentle lights and shadows of the first movement. But the real pleasure was the Andante, based on a theme as simple as a nursery rhyme, which ambulates through the densest and the most magnificent quartet textures before arriving back where it started.