Fig. 2-Diagram of a single pedal chain of an early Hochbrucker harp, seen with the ornamental neck cover removed
Due to sheer lack of extant instruments from the early 18th century, the precise origins of the pedal harp remain obscure. The inventor of the system of foot pedals from which today's pedal harp descends is no new subject of debate, and it is indeed possible that the system was developed by several mutually influential makers. The clearest picture of harp making from this time comes from several surviving harps by a maker by the name of Hochbrucker.
Early pedal harps were not fully mechanized, occasionally having as few as two foot pedals.1 By the 1720s, harps began to be made with the full set of seven foot pedals, one for each tone of the scale. A cutaway of the fully mechanized 1728 instrument by Hochbrucker now housed in the Musée de la Musique is shown below in figure 2. Each pedal was attached to a pedal rod or pedal cable (a) which ran through the body and into the hollow neck, here attaching to a metal lever (b) which was in turn attached at the opposite end to the pedal chain, a series of metal bars, each attached to the next with a rivet.
At each juncture of the chain, placed at the point of each string corresponding to the pedal in question, a crutch (c) was attached. The crutches were L-shaped brass pieces which exited the neck through small holes (pictured from the outside in figure 3). Upon depression of the pedal, the chain would be pulled towards the pedal rod, rotating the crutches.
Figure 3 shows the crutch in the neutral and engaged positions. When engaged, the crutch rotates to push the string against a sharpening nut placed carefully such that, when engaged, the pitch is raised by a semitone. Upon release of the pedal, a spring located near the pillar of the harp (see figure 2) and attached to the extreme end of each chain served to pull the chain back into the neutral position.
The early Hochbrucker instruments depart from previous designs in several important ways. The body of the instrument was now staved rather than square, and the soundboard now made of soft wood, much like the soundboards of bowed string instruments, increasing projection and possibly decreasing the likelihood of breakage thanks to the more pliant and far less brittle nature of soft wood. The soundboard was made with a single large piece of quarter-sawn resinous wood, with the grain running vertically.
On later instruments by Hochbrucker, the arrangement of the mechanism was inverted. The pedal rods were relocated to the now hollowed pillar, and the spring moved to the kneeblock. Two additional pedals were added for a total of 7, one for each note of the scale. This basic arrangement, including the order of the pedals (from the player's perspective and from left to right: D, C, B, E, F, G, A) became the basic model on which all subsequent harps are based. A late instrument by Hochbrucker now housed in the Kunsthistorich Museum in Vienna (inventory no. SAM 565) also proves that Hochbrucker finalized the basic design of the pedals that would be used on all harps until 1820. In this design, a detachable wooden base called the pedal box was added to the bottom of the body. The pedals passed through L-shaped slots cut into the pedal box. Small wooden plugs were installed next to each pedal which served to hold the pedals in the engaged position. Shown in figure 4, the pedal rod, now housed in the column, passed through a small hole in the inner lever and was secured on the other end with a threaded rod-coupling. The portion of the pedal operated by the player, the outer lever, was mounted onto a fulcrum such that, upon depression of the pedal, the outer lever activated the inner, pulling the pedal rod downward. This pedal mechanism can be seen in use below in Video 1 on a French harp using the Hochbrucker design.
Figure 4-An illustration of the early pedal design with the pedal box removed from Pierre-Orphée Érard's 1821 pamphlet, The harp in its present and improved state compared with the original pedal harp, plate 5
