The Mafra carillons: Development of advanced methods in music acoustics for tuning and restoration

Coordinator
João Soeiro de Carvalho

Partnership
Faculdade de Ciências Sociais e Humanas (UNL)
Instituto Tecnológico Nuclear
Escola Superior de Música e Artes do Espectáculo (Porto)

Grant
FCT
ref:
PTDC/EAT-MMU/104255/2008

Abstract

The carillons of Mafra are outstanding musical instruments, now in deterioration. Together, they are the largest surviving 18th century carillon in Europe. Their recuperation deserves special scientific consideration, being a historical collection of bells which must be dealt with careful preservation methods. Its tuning must be non-destructive, and comply with scientific criterion of both musical acoustics and musicological concerns.

The novelty of this proposal is a scientific approach for the tuning and restoration of the carillons, based on both physics-acoustics and musicological advanced methods. Outcomes of the project include scientific reports and technical recommendations that will allow the Portuguese Government to consider a tuning and restoration process rooted in state-of-the-art scientific procedures. A break-through in physics and in musicology, this project will also benefit the importance of an invaluable cultural heritage which has been neglected for decades mostly for the lack of technical and musicological solutions.

The basilica of Mafra is a major work of the baroque, in Portugal as in Europe. Construction begun in 1717, under King John V; it includes a large chapel, a convent, a royal palace, a magnificent library of more than 40K books, and other facilities. Musical apparatus of the basilica includes the only known set of six pipe organs built for simultaneous performance, and the pair of carillons, both from the 18th century (northern tower and southern tower). A public cultural facility, the Basilica has been converted into a museum, the restoration of the six organs has just been finished, but the carillons still wait for a restoration (Doderer, 2002). Southern carillon is often played, as it was restored recently. The Northern carillon is said to be severely out of tune, but its tuning is actually unknown, since it has not been used for more than one century.

Modern tuning of carillons poses a substantial set of problems. On the musicological ground, one has to decide a target tuning, with consideration to both the historical perspective and the performance oriented standpoint. A diagnosis of the current state of the carillon is essential, and the current tuning must be asserted. Research has to be done on the standards of bell tuning at the time and place of the carillon factory, with the knowledge that standards changed all over European factories according to regional patterns of musical taste and performing traditions (Haynes, 2002). On the technical ground, one may state that the non-destructive tuning of historical carillon bells is still a virgin field to be explored. Typically, tuning is performed by removing some of the bell material using a tool-shop lathe. According to the amount and location of the removed metal the bell modal frequencies increase or decrease. This is an expensive, time-consuming and destructive process, which imposes the dismounting of the bells from the carillon structure. Tuning is based on traditional guidelines, mostly based on empirical knowledge (Rossing, 2000). Such destructive approach is well suited for modern bells, but unacceptable for carillons of historical importance - for reasons of preservation of cultural heritage.

The crucial point of this project is the development of objective, physics-based, techniques to achieve adequate tuning of historical carillons without destructive modifications performed on the bells. As far as we know, non-destructive tuning of historical bell carillons using external mass and stiffness adding devices has never been attempted, at least on a scientific ground. Innovative research on multimodal tuning will be achieved using structural modelling and optimization procedures for designing corrective masses and/or stiffening fixtures, while minimizing damping effects, based on analytical/numerical techniques recently developed by the authors (Henrique & Antunes, 2003; Inácio & Antunes, 2008).

Both towers of Mafra possess automatic playing mechanisms (rotating barrel with pegs and levers). An initial assessment has been made, showing that both display a very bad condition, with missing or damaged parts (pegs missing, broken transmission systems, etc.). Although unused, the South tower mechanism has been restored in the 1960¹s, showing signs of a destructive intervention (mostly replaced parts). To the best of our knowledge, there is no sound recording of these mechanisms in performance, no transcriptions of the repertoire, nor even lists of the melodies. However, by way of such initial assessment, it appears that a full restoration is practicable, making possible the performance of old melodies through the operation of the automatic carillons. The recovery of a very important cultural heritage and of a unique tool for historical music performance seems at hand. The historical restoration of the original clock systems, melodic barrels and transmission thus belong to the universe of this project.




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