The timpani are the most important percussion instruments of the orchestra, mainly because they are able to produce notes and the definition of tunings, being able to take part in the harmony of a composition. They are precisely tuned, each one for a given note, according to the directions of the composers in the score, which may be altered as necessary during the course of a piece (usually by changing a key), by tightening or widening the tympanic membrane by means of screws or other mechanisms.
Each drum is made up of a large cup bowl or resonance tank, usually bronze (sometimes in fiberglass), with a calfskin or plastic membrane covering the top. The membrane is assembled (folded) in a ring. Outside of this ring is mounted a metal ring, or counter-arc, which serves, in many types of eardrums, as a means of tightening or loosening the membrane. The main factors that determine the tuning of a drum are the cup diameter and the membrane tension.
The depth and contour of the bowl, which can vary considerably from builder to builder, also influences loudness, a tympanum with the shallow bowl tends to clarify the drum’s main note, while a deep [cup] increases the resonance and emphasizes the [first] harmonics.
Percutaneous idiophon of rudimentary manufacture. Harmonic copper box, resting on the base, rests on a four-foot iron support. Tensile skin, secured by an iron ring, adjustable by 6 iron screws, fixed in the resonance box. It is made by Madeiran and according to the president of the grouping, would have been manufactured in the first decades of the twentieth century, in the locksmith trust, besieged in the health – Funchal.
Portugal, Funchal – Madeira, c. first decades of the 20th century
Owner: Banda Municipal do Funchal (Artistas Funchalenses)
A = 88,5 cm a1 (caixa de ressonância) aprox. 41,5 cm
Ø = 61,0 cm