Voicing

Voicing, in the context of harpsichord-making, refers to the cutting of plectra (also known as quills) in a manner that draws forth a musically enjoyable sound from the instrument and feels controllable to the performer's fingers.

The same term is also used to describe the adjustment of organ pipes after manufacture. Unlike organ voicing, however, the voicing of harpsichord plectra cannot fundamentally transform the sound of the instrument. The tone is largely determined by various construction factors and the stringing materials, not by how plectra are cut. Volume and touch can be affected, along with the degree of shrillness, but not much more.

Historically, raven and goose feathers were the preferred materials for quill. Today, real quills are still used by some makers, while many others use Delrin or Celcon plectra. Both of these are hard, slippery plastics that have a long working life. They don't sound exactly like real quill, though they can get close if worked on by a knowledgeable voicer.

The process begins with ghosting, or setting the silences. Jacks are placed into all register slots, black delrin plectra are installed into all tongues, and the side-to-side position of the register is adjusted until the tongues are about 5 mm from the strings. The plectra are then trimmed from the tip until they just brush the strings when the jack is raised, without actually plucking in the normal manner, though in the bass they are allowed to weakly pluck the strings to adjust for the wire thickness. This process yields a consistent plectrum length of around 5 mm. As each quill is trimmed, the tip (as viewed from the side) is given a chisel-shaped profile to assist the backward tilt of the tongue when the jack descends.

Next, the register is advanced forward so that the plectra project past the strings by about one string diameter. This is the correct "on" position. The correct "off" position is set slightly behind the position at which the plectra ghost the strings.

With the register turned on, the tongue springs in each jack are adjusted so that the tongue tilts back as the jack descends. The severest test is to let the jack down extremely slowly: if the plectrum doesn't get hung up on the string, then the jack will work properly in every playing scenario. If the spring is too firm, stopping the tongue from tilting adequately, the tongue spring is bent back slightly and tested until the jack descends reliably.

Voicing can now begin. The intention is to produce plectra that pluck the strings consistently but not so strongly that the tone is harsh. To the fingers, the plectrum should be neither too firm nor too weak. A gradation in touch from bass to treble is required. The bass needs stronger quills because the string feels like it stretches somewhat before it gets plucked, due to the deeper plucking point in this region. In the treble, the short strings and close plucking point makes things feel stiff, so a weaker quill is needed.

This process can be expedited by using quills of differing thicknesses. Before ghosting, I experimented with 8 different quill thicknesses, discovering where it helped to change from one thickness to the next. I erred on the heavy side, since of course a heavy quill can be thinned to maker it weaker, but nothing can be done to strengthen a weak quill. Ultimately I used 6 different thicknesses, changing approximately every tritone to a thinner quill.

Voicing requires controlled cuts on the sides, arrises and underside of the quill, all of which thin the quill and reduce its stiffness. When done sensitively, the resistance of the quill as it raises the string seems to yield slightly just before the pluck, which I find feels quite controllable to my fingers.

The customary tools for voicing are shown below:


A set of wire cutters helps to trim excessively long plectra from the back. The hemostat acts like a set of pliers for installing and removing quills. Either a #11 scalpel blade (shown above) or a #11 Xacto knife blade are used for cutting the plectra. A voicing block—in this case the hard end-grain surface of an ebony block—acts as a little cutting board.

Once both registers received their preliminary voicing—a lengthy process that took two days of on and off work—the jack end screws were adjusted to locate the plectra a consistent distance below the strings. I first unscrewed each screw considerably, lengthening each jack to the point that the plectrum was actually above the string even with the jack fully lowered. Then I screwed back in until the plectrum just barely slipped under the string. At this point, I gave the rear row of jacks (the "back 8") 3 more half-turns, and the front row (the "front 8") 6 more half-turns. This difference separates the plucking instant between the two rows so that, if they are both turned on and played together, they won't pluck at exactly the same time. Otherwise the touch would be extremely heavy.

With these preliminaries out of the way, the instrument was played for several days and any discrepancies were corrected by replacing plectra, shaving down plectra, or adjusting the jack end screws further. These screws should not be cranked around much once they are set, but sometimes one or two more half-turns make a positive difference.