The first thing I settle on in writing a new piece is who's going to play it on what instruments. In this case it's my flute playing friend Susan and her harp playing friend Carol. On my recent trip to Vermont, they played Mosaic for me. I wrote it in 1994 for Susan on flute and me on piano and they had worked it up as a flute and harp piece. It really works that way, but I kept thinking a piece written expressly for the two of them would better exploit that wonderful pairing of instruments.
I've known Susan since the '70's when we were at Shenandoah Conservatory together. I've never known anyone to more fully inhabit the music she makes and I've never heard better tone on the flute. She's a pro level player, so the only concerns about the instrument are those inherent in it. Her low number Hanes has a B foot, but I never write that note as other flutes might not have it. The E above high C on flutes is the hardest note and worth avoiding if possible. Being a product of the music education system Susan. tongues. every. single. note. un.less. o.ther.wise. no.ted. It was for Susan I first wrote music for small ensembles (Dr. Andy on cello and me on alto flute or piano) and she loves the new and unusual, so besides writing things for her I think suit her personality, there are no limits on what I can try.
I've just met Carol on this recent trip. She plays the harp very well, and like Susan, has a wonderful Louisiana laugh. She's also pro level, so instrument considerations are of a general type. I've never written for harp before and only know what I read up on and what Carol showed me in a brief clinic after she and Susan played Mosaic. The main things seem to be the harp prefers flat keys, too many accidentals or key changes mean a lot of messing with pedals, and she said an octave and a third was a good limit on chord fingerings. She also made the point that when a harp plays high notes, it's good to have low notes with them so they won't sound tinny.
One thing I want to go for is having Susan in her low and mid ranges more than the high. Playing softly in the high range of the flute can be done, but it's tough. There was a blend of tones when Susan was in her mid range where the harp and flute sounds really melded. The high flute range can be used, but it will tend to overpower the harp. The other thing for me to keep in mind is that the harp strings are plucked by fingers, not struck by levered hammers as on a piano, so that loud percussive side to the piano is not something the harp can do.
Once things get going, I may add a third part for alto flute or violin or viola. When I was in Vermont and making music with Susan I mostly played an electric keyboard I'd taken, but we did try one duet I'd done years back for flute and alto flute. I didn't play that well, being very rusty on the alto, but the combo of those two flutes creating difference tones on close harmonies is an amazing sound, and one the harp would frame nicely. The alto's range is exactly that of a violin (starting down at the G below middle C) and the upper three strings of a viola and Susan has family members who play them, so the alto part could be covered by one of them when I'm not in Vermont. If written, that part would be easy enough for me to play and there would absolutely not be any E's above high C (concert B as the alto is in the key of G) and low D (concert A) would be as low as I'd want to go.
photo - yard violets, which some consider flowers and not weeds.