Harp design and construction
Chris Waltham · The Journal of the Acoustical Society of America · 2005
The harp is an instrument with a set of plucked strings connected directly to the sound board. Thus the requirement that the sound board be very light for efficient radiation is pitted against the requirement that the strings be tight enough to maintain harmonicity. These factors have determined the evolution of the harp since Sumerian times. As materials and construction methods have improved, strings have become tighter and sound boards lighter. Large harps have total tensions in the range of ten kilonewtons. The material of choice for the sound board, usually spruce, is pushed to the limits of its strength, and even professionally built concert harps tend not to last more than a few decades. The strings themselves are made from a variety of materials, wrapped or plain, to balance the physical requirements of tension and feel, with the acoustical demands of harmonicity and tone. Historical materials such as copper and silk have given way to steel and nylon, although gut still has a niche in the mid-range of a concert harp. These physics and engineering issues will be considered in the context of practical harp construction.