The modern double Harp is a unique instrument, with it's 47 strings, and use of pedals to change pitch. Writing for the Harp is a challenging process, as the composer should have a decent knowledge of pedal combinations, and the pitch changes these mechanisms invoke. There are 7 pedals on a modern double Harp, being from left to right, D C B E F G A. The pedals have two positions, with 1st position shifting all the strings associated with that pedal, a semitone, and the 2nd position, a tone. This is a very brief summary of Harp pedal operations, and users are encouraged to seek more extensive resources to learn more about this instrument, and the conditions and limitations invloved in writing for Harp. We will add further information in the future here..
In the normal playing position, the harpist places 1 foot either side of the harp, and rests the instrument against his or her right shoulder. Notational music for the Harp is normally written on 2 staves, as for the piano, with the right hand using the upper stave, and the left hand the lower. Like piano music, treble and bas clefs may be used, but in addition, and unlike piano music, this can apply equally to either hand. Both hands can be employed in the upper register, but the lowest notes of the instrument are normally played with the left hand. Players use their thumb, and three fingers on each hand to play, and the little finger isn't used at all. If chords of more than notes are intended, the player uses both hands.
It's recommended that users new to writing for Harp should research the notational, and playable requirements closely, and extensively. The Harpist requires time to shift pedal positions, and may have to extrapolate alternatives for chords, if rapid pedal changes are required. In this particular example, the composer would use two harps.
Some chords are unplayable on a Harp, due to the limitations of the pedal system, so the composer should keep this in mind as well. For users recording from sample libraries only, this may seem a challenge they will not face, but the resulting recording will identify the reality of a Harp passage to skilled listener or competent player.