(Tip no. 66 from “100 Orchestration Tips,” Part 4: Harp)
The most resonant sound from the harp occurs when the tuning is set to flat keys. This is because of the double-action harp tuning mechanism. The most relaxed, longest tuning of each string is when the harp tuning pedal is in the up or flat position. To get a natural, the harpist tightens the string by pressing the pedal down to the middle notch. The sharp notes are even one degree tighter, and slightly less generous in sound. This is the reason why a wise composer will set harp solo works in flat keys, the flatter the better. C-flat is best of all, with all strings at their loosest.
Hopefully, some of this group took the time yesterday to listen to the Pierné Konzertstück video that I linked below, and did some score-reading along to it. What you probably observed right away is that the key signature for the whole orchestra (except for the transposing instruments) is set in G-flat major. Pierné is giving the harpist a very agreeable key in which to do her soloing, and making the orchestra do all the work. There are definitely risks to this approach. For one, in six flats, you can only modulate down one key to C-flat, so most of your adventuresome tonal shifting has to go counterclockwise around the circle of 5ths. The other concern is the extreme heavy lifting that the orchestra must do to accommodate such a thorny key signature. Yes, a pro orchestra will handle it, but with a semipro or youth orchestra situation, the results are iffy. It will require a higher level of focus on intonation than the average amateur player may be used to. Just listen to the uncertain intonation of the string section in the video.
Therefore, Pierné set himself a trap. His piece is the ideal work with which a young virtuoso might easily win a contest, or take on the road. Yet find the community orchestra that really wants to play it! While its key signature doesn’t entirely take it off the menu, it still adds to the general reluctance of smaller orchestras to feature harp soloists.
I faced the same quandary with my harp concerto, and solved the problem enharmonically. The biggest concern was to have a firm relationship between the string section and harp soloist – then to build on that with the other sections (especially the winds). So I conceived of the two outer movements being written in C-flat major for the harpist, and E-Lydian for the strings. In the excerpt below, you see the harp staff bearing seven flats, meaning all harp strings are at their most luxurious and resonant. Meanwhile, the strings are in four sharps (E major), occasionally playing an added fifth sharp on A. E major is a great key for strings, and no big stretch for the winds, especially with an A clarinet player reading G major. About the only concern will be whether the strings tighten their sharps a little too much, as can sometimes happen. We’ll see in April.