Haydn’s ‘Frog’ Quartet owes its nickname to the ear-pricking effect in its final Allegro con spirito, where the players alternate between two strings for fast repeats of the same note. The fun starts right from the opening Allegro, though, where he teases us with cadences that never emphatically resolve, creating music that’s always up in the air. Sitting at the centre are a lilting, siciliana-style slow movement, and a Menuetto with playful accents, hesitations, and offbeat rhythms. Ravel honoured the Classical tradition in the architecture of his Quartet of 1903, which shines for his own deft exploitations of the instruments’ colours and timbres. Lyricism characterises the first movement’s ebb and flow. The second’s rhythmic propulsion is offset by an elegiac central section. The slow movement echoes material from the first, as does the dramatic finale.