The voice parts are written in conventional musical notation and the lute part in tablature. An unexpected problem arises. My lute is tuned in G. However, the songs we chose for the concert appeared to require lutes tuned at four different pitches (G, A, C and D) in order for voice and lute to come out in the same key.
What's the answer? Well, for most of the songs I ended up transposing, which is a shame since it completely changes the fingering of the lute parts, rendering the tablature useless.
So, should I have four lutes by my side, switching instruments for each song as required? It seems impractical, not to mention expensive. Is that really what the composers intended?
Jonathan Le Cocq also thought this was odd, and published a study about it in the Lute Society Journal, 1992. 68% of the air de cour repertoire appears to require a lute in A, 27% a lute in G, and the rest lutes at other pitches. However, the A-lute pieces are strongly associated with a certain set of keys: C major, D minor, and G minor. Played on a lute on G these would come out in B flat major, C minor and F minor. It's possible, then, that the songs should sound in those keys and that it's the voice part which has been transposed up by a tone, to avoid having to write too many flats. In other words, I can stick to playing everything on my G-lute and the singer can adjust. That's just fine.
As it happens, though, lutes did exist in many different sizes and pitches. As Matthew Spring explains in his book The Lute in Britain, many continental lute duets are for instruments at different pitches, often a tone or a fourth apart. Trios are found for lutes at the unison, fourth and fifth, and Adriaenssen's quartets require lutes in A, G, E and D. So maybe I need to buy more instruments. Lots more instruments...