[CAUT] harpsichord information

[Fred Sturm]

On Apr 22, 2009, at 7:16 PM, Ed Sutton wrote:

> The Challis is something of a historical instrument in its own  
> right. One I worked on had a cast aluminum frame, aluminum  
> wrestplank, wood soundboard with brass tubing bridge. Later he went  
> to aluminum soundboards.

	I've seen a couple with aluminum soundboards. They are actually a  
sandwich of two sheets of aluminum with some kind of mesh (sort of  
like metal lath) between. Remarkably stable tuning, and reasonably  
good tone quality - better than one might guess.
>
> It was mechanically sound, and not unpleasant, but was boring  
> compared to more historiacally founded instruments. It didn't have  
> the change of color from register to register which is such a  
> delight in a good small harpsichord. The Challis was even and bland,  
> as I remember it.
>
> The jacks were machined out of some kind of hard plastic  
> (bakelight?) It had separate damper jacks. I wondered if the jacks  
> would hold up much longer.

	A customer of mine had one, and her husband was a chemist. He became  
interested and investigated, found out it was more or less a rubber by- 
product that Challis used for the jacks. They developed a kind of a  
surface "residue" (sort of like oxidation) over time, which caused  
friction with the metal jack guides. This instrument had the problem,  
and I sanded all the jacks lightly to deal with it. The material  
didn't seem to be at all brittle.
>
> I might as well admit I replaced the leather plectra with delrin.  
> Challis would have shot me, but it didn't make much difference in  
> the sound.

	For the experience (being a bit of a masochist I guess) I replaced  
all the leather plectra (which were old and breaking) with new  
leather. Not an easy task to get a strip just the right cross section  
to fit snugly into the mortise, not to mention the voicing part. I did  
develop some techniques (you need a VERY sharp knife to begin with,  
and most trimming needs to be done downward against a cutting surface  
- wood block). These are the long, early to mid-20th century leather  
plectra, nothing like the peau de buffle used on some historic French  
instruments. In any case, I thought it might be just about as easy to  
do leather as to convert the mortises for delrin, and be sure the  
wedges to hold the delrin would stay in. And then I would have the  
skills to do occasional replacements as the need arose (hasn't yet ;-().
>
> Ed S.


Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu


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