Technical Library ACTION VI: Delrin conversion Entire Contents Copyright ©2010 CBH

Two Goble harpsichord jacks: The one on the left retains its original leather plectrum, while the one on the right has had the original tongue replaced ready for a delrin wedge to be inserted and voiced.

Delrin conversion…
The original leather plectra of many harpsichords made in the 1950s and 60s are well past their use-by date. As a consequence, most of these twentieth century revival instruments now have unreliable touch, with weak, broken or missing plectra. Few makers or technicians consider it good practice today to try to replace the original leathers with fresh, but these instruments can be resurrected by converting the tired leather plectra to delrin or celcon and revoicing.

We have movies prepared to show the process of delrin conversion in harpsichords by three prominent English makers: Morley, de Blaise and Goble. Each movie has accompanying explanatory text:

• Morley harpsichords can be converted using proprietary moulded delrin plectra with a cubic base which snaps into the vacant tongue mortise after the original leather is removed.
• The de Blaise instruments are converted using “standard” delrin wedges, held in the wooden tongue by the original leather stub which has been carefully trimmed for the purpose.
• Early Goble instruments are best converted by replacing the original tongues with modern Goble tongues, mortised to hold the usual delrin quills (see picture at right).

We regularly undertake delrin conversions either in the field or our Sydney workshop. The work is tedious and time-consuming. It should be noted that while the touch and reliability will be much improved, the subject harpsichord remains a thirty- or forty-year old instrument with the typical heavy case construction of the period and corresponding lack of tone. (This is reflected in the resale value of these instruments—much reduced from their true replacement cost or in comparison with instruments of decent quality based on historical principles of construction.)

		Morley delrin conversion Carey Beebe demonstrating the conversion of the original leather plectra to delrin on a Morley virginal.
		de Blaise delrin conversion Carey Beebe demonstrating the conversion of the original leather plectra to delrin on a de Blaise harpsichord.
		Goble delrin conversion Carey Beebe demonstrating the conversion of the original 4´ leather plectra to delrin on a 1974´ Goble harpsichord.

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