Voicing

I finally started voicing the harpsichord in early February.

First the jacks have to be cut to the correct length so that the plectrum will be about 1.5 mm below the string. On this instrument all of the jacks are going to be very close to the same length but each one will have to be individually adjusted so at this stage I aimed to cut them just slightly over length.


Almost done with the jacks for the back 8' - two of the jacks in the picture have plectra fitted to them so that I can check that the length of the jack is correct.


Voicing is conceptually very simple - all you have to do is insert a plectrum into the slot in the tongue of the jack, cut it to the correct length and remove a few thousands of an inch of material from it with a sharp knife until the note sounds right then fit a small piece of damper cloth into the slot at the top of the jack so that it damps the string when the key isn't pressed. Repeat the process (for this instrument) 106 times and you are (almost) done.

It turned out that I had perhaps been a little too cautious when cutting the jacks to length - the plectra were mostly either touching the string or sometimes just a little above it so I had to take 1 or 2 mm off the length of each jack. It took a little while to figure out the most efficient way of doing this but eventually I settled on using some 80 grit sandpaper to remove most of the excess length and then making the final adjustments with a fine toothed file.

My main goal for the initial voicing was just to get the instrument playing and to get some idea of what it could do without worrying too much about the details. I had voiced a few plectra for my French Double but that was much easier because the rest of the instrument was already voiced so it was very clear what it should sound like and it was even possible to look at the plectra for adjacent notes to see roughly how the plectrum should be cut. This was different because I was starting from scratch with only a vague idea of what the instrument could or should sound like.

I started with middle C and then did the notes one and two octaves above and below - initially just getting them to sound reliably and then trying to thin the plectra down to the point where the note started to sound "right". One thing that became apparent very early on is the extent to which voicing is both a tactile and an aural process - at first the plectrum is far too thick, the key feels very stiff, there is a very strong pluck and the sound is harsh but as the plectrum is gradually cut thinner and thinner both the touch and the sound improve and both start to feel "right" at about the same time.

Once I got all of the C's voiced, I did the G's and then E's giving me a C major triad.

Here is what things looked like at about that point. All of the plectra have been fitted to the back 8' set of jacks and cut to approximately the correct length.

The jacks that have been voiced have dampers fitted to them.

In the second picture you can see that some of the unvoiced plectra are still sitting above the strings because the jacks have not yet been filed down to the correct length


Then it is just a matter of going through all of the other notes one at a time.

I think that the initial voicing of the 53 notes of the back 8' took me about 10 hours over the course of a week. A lot of this time was spent just getting the jacks down to the right length. Cutting the plectra was also very slow at first, but started to get a lot faster by the time that I was about half way through. Partly this was a result of acquiring the manual dexterity to manipulate the jack, the voicing block and the knife efficiently but the really big time saving came once I started to learn how much the plectra needed to be cut in order to make a particular change in the voicing. This greatly reduced the number of times that I needed to try the jack in the instrument.

Here is how things looked just after the the initial voicing of the back 8' was finished. The blue masking tape on the jack rail is a temporary measure to hold the cloth padding the underside of the jack rail in place.


At this point the instrument was actually playable for the first time and, although the voicing was still quite rough it was possible to get some idea of how it was going to sound.

One of the first and most obvious things is that I like the way that the keyboard feels - the depth of touch is quite shallow and I had been a little concerned about how that would feel but in fact it feels really good - there is a very direct connection with the sound and it just feels "right".

Overall the sound was good as well although I thought that the top octave was perhaps a little weak and the octave below middle c was a little loud. This is really quite difficult to judge when sitting at the keyboard and I noticed that the balance between different parts of the instrument sounds noticeably different when standing over it.

I played the instrument for a few days and then started to rework the voicing of the back 8'.

Some of the plectra, although they sounded reasonable had been cut very unevenly and others had been cut very narrow and were clearly not going to be amenable to any further voicing so I set about replacing them. I also wanted to see how much sound I could get out of the top octave so I replaced most of those plectra and left them all voiced just a little bit too strongly. In the end I probably replaced more than half of the original plectra but this went much faster than the original voicing and only took a couple of hours.

For the next 2 weeks I just played the back 8', fixed problems as they came up and every few days went over the voicing taking just a little more off any notes that seemed a little too loud.
Overall there were very few problems although I did have a few "hangers" that were difficult to diagnose at first. A "hanger" is a jack where the plectrum fails to slip back under the string when the key is released and instead "hangs" on top of it. This can happen if the plectrum is too long or isn't cut correctly or if there is a problem with the jack tongue or the spring that prevents it from swinging back to allow the plectrum to slide past the string.

The problem notes were almost working but sometimes the jack tongue just wouldn't swing back quite far enough to allow the plectrum to get past the string. This puzzled me until I noticed something that almost all of the jacks with this problem had in common.

The spring that holds the jack tongue in place is just a small piece of steel wire that presses against the back of the tongue and runs down through a small hole in the jack body and ends up in a slot in the back of the jack. The problem jacks all looked like this one where you can clearly see the end of the steel wire in the slot in the back of the jack body.

The problem is that the steel wire is not seated properly in the slot. Because of that the part of the wire that presses against the back of the tongue is leaning forwards at a slight angle and applying just a little too much pressure. The solution was just to push the wire right down into the slot as seen below and suddenly the jack starts working correctly.