home>eki>A large fretted clavichord based on Hubert
Length = 1412mm a table is needed
2002 12(DEC) 13 Akihiko Yamanobe
I learned all the method of clavichord-making from Mr David Bolton in England. He taught me on the drawing he wrote. It is a middle size instrument, 120cm long, fretted. First I was making them for harpsichord players or early-music enthusiasts. But these two years I had been making clavichords for organists and pianists. Some pianists gave me nice letters telling that not only they could practice clavichords at midnight, but also they could improve the touch or tone of the piano and occasionally they could understand the music its-self better on the clavichords.
I did not intend to make a large unfretted instrument but I wanted to make a larger fretted instrument. I look for such a drawing. The 1789 Hubert is drawn and shows us enough detail. But it may be an special design on some points. First the bass open-wound string area may be larger, because the S-shaped bridge has a very open curve in the bass, so speaking length is generally shorter in the bass in comparison with the other Hubert's large fretted instruments. Secondly it has a little longer c2-scale of 264mm. Other fretted instruments build among 1784 to 1787 were designed to string plain string (not wound) to the largest area (this makes the bridge close curve in the bass) and have shorter scale about 255mm. The scale of 255mm makes us possible to tune it at a pitch of 440Hz using some brass wire widely produced. I will make short report on the instruments I make.
1. Main drawing
I reffered the drawing by Horst Rase on the 1784 Hubert in Musikinstrumenten-Museum Berlin which Mr. Koen Vermaij named 84(4). The general size of a case, hitchpin rails and wrest plank are close to the drawing.
2. String length and the bridge
I took the genenal shape of the bridge from the drawing I refferd above, but I calculated the length of each strings and redrew the bridge. I reffered alsothe string length of this instrument mentioned on Mr. Coen Vermaij 's book. Generally speaking the string lengths from top note to c1 (middle c) are near just-scale (same tension if strung with same-thick wire) . It has shorter length than the just-scale, at the highest notes. Below c1 the lengths of each notes are gradually shorter than just-scale.
The bridge is made of hard maple. The bridge is glued to soundboard by natural glue. The soundboard is glued to liners, berry rail and wrest plank with natural glue too. I use natural glue around soundboard only.
A few years ago I used red cedar for the soundboard of a clavichord as I have much red cedar for making Italian poligonal instruments. But it was not a success for a 18th century clavichord. Next wood was a spruce from the north America. Unfortunately Japan is still importing wood from the US and Canada to build a house. I was once astonished to find the A class spruce which will be used perhaps for visible part of a house, is good enough for a soundboard. So some of my clavichords have such soundboards. Recently I use mainly spruce from Europe.
The problem is, in Japan, the humidity of air. Generally the air is wet in comparison with Europe, but in the centre of Tokyo, the humidity often goes down quickly towards zero. The lowest, I remember, is 10%. So, I use very dry wood for a soundboard. Yet,it is very difficult to make a musical instrument which will kept in Tokyo.
4. Soundboard barring
The design I use is shown on the figure 1. I have not met such barring on drawings. But I believe it is one of natural designs. The two bars goes in chamferd area on the top of the liner not touching the liner itself.
5. Listing cloth
I am not actually the first to use a new material. But I use microfibers for listing cloth. It is produced by a company Toray, developed for the use in a cabin of cars and meeting rooms. The microfibers are designed extremely fine and well configured in order to makes less noise than felt or other coth. The small noise made by the microfiber is near white noise. This may be the reason we feel natural or comfortable even though it is not a perfect dumping material.
6. Key design on clavichords
6.1. what is a key in clavichord
You may know that the key of the clavicdhord is designed to push the strings up with a tangent. When you push a key with your finger the opposite end of the key goes up and the tangent on the key attacks the strings. This simple movement is the work of the key. But ...
I first understand that the key balance is the only important, because in some cases the key balance is not always good unless you put some lead waight on the keys. My idea is that a key of the clavichord is a bow of stringed instruments such as violin viola cello, or a hammer of dulcimer. You may think that it is the same with harpsichords. Yes. the keys of the harpsichords work the same with clavichords, and the keys are also important on the harpsichord. You will at once recognize if it is a light and good balanced key or not, on a harpsichord. But on the harpsichords there is an action between the key and the string. There are felt between the key and the jack, free space between the felt and the jack. There are a jack,tongue pin,tongue, and plectrum. On the other hand clavichord has no action between the key and a string. There is only a tangent and free space between the tangent and the string. This fact presents us a great defference between harpsichord and clavichord. When you play the violin, there is only a bow between you and the string. So you need a very a good bow. Let's think about what is a good bow. You may ever tryed no-exellent bow which looked fatter than normal bow made in softer wood. The fat bow has enough strength but it has too much mass out of the center of the bow. These mass vibrate itself randomly. These vibration is the disturbance of good sound. Of course you cannot see the vibration. So, let's thik that when you drive a car, you may find a little difficulty if you have a very big man sitting in the back seat on the left or right. Mass apart from the center of the car makes you difficult to drive especially when you turn to the left or right. The same thing happens on the bow with much mass apart from the center. So is the key of the clavichord. The key of the clavichord is not made in hard wood but it must be shaped up to the limit too. On the clavichord, the part which should be shaped up is an area between balance pin and tangent, and an area between balance pin and key front which is shown below. These parts have more than enough strength and have too much mass apart from its center if it is not shaped up. You will notice this at once when you play a good clavichord with shaped-up keys. You will feel the atack clearer with these keys.
6.2. key carving
I hope I had made myself clear in the statements above and you will use the keys of clavichord like bows of stringed instruments.
On the instruments I am making, the keys are carved not only at the top but also the bottom a little. Underside of the key tops are carved as much as possible. The wood I use is Alder which is very good for carving.
6.3. key tops
The key heads of natural keys are 3.3mm thick and the tails are 1.4mm thick. fig.2 I first know this design on the drawing of Hubert 1784 Edinburgh. I had knowticed that when I glued key tops, the tone changed. Near finishing a clavichord when all the strings and tangent are set but not the keytops yet, I was lucky to know a kind of natural sound of clavichord without keytops. So I wondered how I could keep the natural sound even the keytops are glued. One solution is to use very thin key tails. The key tail is long enough (about70mm) and glued to a different wood that is a key lever which is normally softer wood. The two kinds of wood may have a different transmisson-velocities of vibration. The thick tail makes a large mass apart from the centre of the key. I think these causes the change of timber after the tail is glued. Early models with short key-tails may not have no significant difference. fig. 3
7. Hitch pin rail (treble)
I make the upper part of the treble hitch pin rail, thick in the right touching the berry rail, thin touching the bass hitchpin rail. This will loose less energy and resonance will be kept for a long time.
The finish is Japanese lacker called URUSHI(chinoiserie). Urushi originally is a name of a tree which is widely spread in south and east Asia. Urushi dries very slowly, so a clean room is required. There are many urushi atelier all over in Japan. Urushi table wear is also common besides china wear, till now in Japan. Some wooden bowls I use daily are finished with urushi.
There are many kind of urushi finish in Japan. They look different and have often each name from the name of its town. This instrument has SURI-URUSHI from the district Kiso in Nagano prefecture. This is so thin or light finish, that you will see original wooden grain. I choose this thinking that it will not make a significant change to the timber of the instrument.
9. The wood used
case ..................Japanese birch,Japanese cypress called HINOKI
or other wood
bottom.................pine (glued up small pieces)
upper part of hitchpin rail
...........Japanese pine of Hokkaido called EZOMATSU
bellyrail..............Japanese walnut or other Japanese hardwood
sharp keytops..........bone topped rosewood
lid....................Japanese pine called EZOMATS
or the same wood as the case.