The cutting of the dampers
Another feature seen in most books on harpsichord construction which doesn't correspond to historical practice are the so-called 'flag' dampers with flat horizontal lower edges. Dampers cut like this are a feature that I have seen only rarely in historical instruments1. Instead the dampers are usually angled sharply upwards relative to the horizontal. In the instruments of the Ruckers/Couchet family, for example, the dampers are placed in oval holes instead of vertical slots and have a characteristic 'mouse-ear' shape as described in my book on Ruckers. Because of their rounded shape the edge of the damper that comes into contact with the strings is always angled relative to the horizontal. Many English instruments have survived with their original dampers and the dampers on the 8' jacks at least (see the footnote below) are cut with a straight edge angled upwards from the horizontal at an angle that is normally greater than 45°. A number of historical French harpsichords has survived with delicately rounded dampers which seem to date from the historical period and which also come into contact with the string at a steep angle to the horizontal. Therefore in all cases where the damper does not land flat on top of the string, but where instead the damper is sharply angled relative to the horizontal, the string is brought gradually to rest as the damper's edge gets progressively closer and closer to the centre of motion of the string. This effect is extremely important in damping the bass strings where the amplitude of vibration is greatest and where the energy imparted to the string is large. It is also particularly important in Flemish muselar virginals where the strings are plucked much nearer the middle of the string than normal and where the amplitude of vibration of the string is therefore also great over a large part of the compass.
Even if the maker's original dampers have not survived, the intention of a maker to have designed his jacks to have dampers with a sloping edge is usually apparent from the way the jacks are made. It is necessary here to observe how deeply the damper slots are cut. If the maker intended the dampers to have flat horizontal lower edges, then the bottom of the damper slot need only be cut to a level above the level of the quill in the tongue. But normally the damper slot is cut to a depth that reaches well below the level of the quill. (For example, look at this photograph.) The damper is then pre-cut with a sloping lower edge and is then located in the damper slot in a position that reaches right to the bottom of the slot. It is then pulled towards the front surface of the jack in such a way that only a short section of the business end of the quill projects beyond the damper (see the left-hand photograph at the top of this page). In my experience most historical jacks in virtually all schools of harpsichord making are made with damper slots that reach well below the level of the quills. I consider this in itself to be sufficient proof that such jacks are intended to be fitted with dampers that reach right to the bottom of these slots and cut with edges that come into contact with the string at a steep angle to the horizontal.
Another feature of historical harpsichords which indicates that the dampers were not cut with a horizontal lower edge is the string spacing. It is particularly clear in the case of French harpsichords where the 8' strings are usually spaced very close together. If the dampers in an historical French harpsichord are cut flat and horizontal at the bottom, then it is very difficult to keep the dampers of one register from touching the strings of the second choir. If, however, the dampers are cut with sloping lower edges, this problem obviously does not occur. The problem is not as acute on instruments with only two 8' sets of strings such as most Italian harpsichords where the strings could, if desired, have been placed further apart. However, many Italian harpsichords, in order to give as much space as possible to the jacks and to allow for long quills, also have the adjacent strings placed very close together. This again makes it difficult to use dampers with flat lower edges without getting interference with the second set of strings. Also if the instrument had been designed with flat horizontal flag dampers in mind in such a way that the damper should stay in contact with the string in both the inserted and de-inserted position, then the damper would touch the adjacent string and damp its vibrations. The problem doesn't exist, however, if the dampers are cut with a sloping lower edge since then the damper doesn't come anywhere near any strings other than the one the damper is meant to damp.
I see the fact that the damper slots in the jacks of most historical harpsichords, virginals and spinets reach to a level well below the level of the quill slot and the close spacing of the two 8' choirs of strings as both indicating that the dampers in instruments with these features were cut with sloping lower edges. This evidence is backed up by many instruments with surviving dampers which seem to date from the historical period and which are almost always cut with sloping lower edges.
The sloping damper produces an interesting effect in an instrument with two 8' strings for each note. If one 8' register is turned off, its strings are left undamped and free to vibrate in sympathy with the other 8' register. When the jack of the note being played returns to rest it will damp its own string but the undamped 8' string vibrating in sympathy will continue to sound after the key is released. The effect is particularly striking in pieces where the music modulates rapidly into unrelated keys. The result is a tendency to add further piquancy to the key shifts. It is an effect which, although most modern ears are unaccustomed to it (and most harpsichord players and builders rebel violently from it, it must have been known to the historical musician and composer and was probably even a feature that composers expected in rapidly modulating pieces. The effect obviously occurs only when one register is not being used. When both registers are engaged the improved efficiency of the sloping dampers is noticeable and adds to the distinction between the rather ethereal effect of playing with one register with the second vibrating in sympathy, as opposed to the pungency of the instrument's rapid attack and immediate damping when playing with both registers engaged.
1The most notable exception to the rule that dampers are cut with sloping lower edges is found in the 4' jacks of English harpsichords by Kirckman and Shudi. The 8' jacks have dampers that are cut with sloping lower edges, but the 4' dampers have flat lower edges.
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