Organ-piano

Franz Xaver Christoph’s claviorganum is undated but was probably built around 1785. It is thus the earliest combination instrument of this type to have been made in Vienna. It is also probably the only one in the world that is still playable in concert. The “Stoßmechanik” with hammer heads pointing towards the player allready has adjustable jacks; the hand stop for raising the dampers was to the side of the keyboard. This provided two different registers (playing with lifted dampers, and thus with pronounced reverberation / playing with a dampered sound); the use of pedal in the pianistic sense is, however, impossible. It is possible to create other tonal nuances on the piano by using the moderator. The pipework is activated by a sticker action located underneath the keyboard. A special feature of all combination instruments is that by modifying the touch (hard, accentuated touch or soft, legato style of playing) either the sound of the piano or that of the organ can be emphasised. The sliders of the four organ registers are divided so that bass and treble can be “stopped” separately. A unique feature is the 16’ reed stop. Although this is the lowest register, it is so rich in harmonics that it provides impressive highlights to the total sound. Originally a Venetian swell was located between the pipework and bottom of the piano to produce dynamic shading in the organ register. (rh)