Two unison strings per key and two registers of jacks are provided. The apparent compass of the keyboard is from C/E to c´´´. The remains of pedal connections can be seen on the lowest eight keys.
The sides of the harpsichord are 5⁄32" thick; the bottom is 9⁄16" thick. The sides and lining are supported by knees that do not extend clear across the bottom of the instrument as they do in the virginal.
The knees are small triangular pieces, as shown in figure 8. Since the added tension of the second set of strings demands a somewhat more substantial framework than that employed in the virginal, a series of braces are attached to the floor. These are connected to the lining by several diagonal braces (fig. 9). This produces a remarkably strong but very light structure. The keys (not shown) are of more constant length than those of the virginal; therefore, the touch is much more uniform.
Figure 9.—Framework of harpsichord. a, wrest plank; b, belly rail; c, rib; d, bottom brace; e, diagonal brace; f, knee; g, lining. Scale, 1:8.
Figure 10.—Layout of harpsichord soundboard. Scale, 1:8.
The wrest plank is supported by two end blocks, against which the partition behind the action (called the belly rail) is also placed. The soundboard is glued to the top of the belly rail. The wrest plank is veneered with cypress, giving the appearance that the soundboard extends over it. The jack guides also rest on the end blocks in the space between the wrest plank and the belly rail. Figures 8 and 11 clarify the arrangement of these structural features.
Figure 10 shows the layout of ribs, bridges, and strings on the soundboard. The soundboard is about 1⁄8" thick. The bridge on the wrest plank tapers in height from 3⁄8" in the treble to 7⁄16" in the bass and in width from 5⁄16" to 7⁄16". The soundboard bridge measures about 3⁄8" by 1⁄4" and has virtually no taper. The soundboard does not have a rose, although that decorative device is fairly common on Italian harpsichords.
The jack guides are built up of spacer blocks held together by thin strips along the sides. There is now no provision for moving the guides, although plugged-up holes visible in the right end of each guide suggest that they originally could be disengaged. In Italian harpsichords generally, the jack guides were controlled by knobs projecting through the sides of the case. Sometimes these harpsichords had levers pivoted on the wrest plank and attached to the guides. The Ridolfi case has not been patched and there are no holes in the wrest plank where levers could have been attached; so, the guides probably were not intended to be movable.