Hillbilly Passacaglia - an original composition for banjo and three cellos
“The term Passacaglia derives from the Spanish pasar (to walk) and calle (street)... The passacaglia was redefined in the late 1620s by Italian composer Girolamo Frescobaldi, who transformed it into a series of continuous variations over a bass (which itself may be varied).”
This piece started life two years ago as an idea – a harmonically ambiguous banjo ostinato which would be overlaid with lush string parts as a contrast to the bouncy tone of the banjo. The ostinato is pentatonic, starting on the second degree of the major pentatonic scale, thus meaning that there are no thirds or sixths, and thus no clarity as to whether it exists in a major or minor mode – the key note is D, and the scale is D, E, G, A, C. The ostinato is is 9/4 time, which adds another layer of ambiguity as it switches between a 5-4 crotchet grouping and something more like a pair of 9/8 groupings.
The cello ensemble has a few bits of material – a closely overlapping section that oscillates between mixolydian and dorian, a melodic folksy section that’s strongly in a dorian mode, and a sort of bluesy section that whilst in mixolydian, borrows flat thirds and sharp sevenths. These sections are repeated in various forms, with a middle section that pushes the tonality out just about as far as it can move while still being accompanied by the D pentatonic banjo ostinato. (The move to a Bb major ninth chord fully voiced with double stops is probably my favourite bit, although the modulation from Ab/Eb to D mixolydian over a bar at the other end of the middle section is quite nice too.)
The character is very much the sort of bluesy dobro music you might find underscoring a scent of tumbleweeds or a swinging saloon door – the title pairs these images with the traditional and formalised idea of the Passacaglia which the piece largely follows.