The Timpani is the most important Percussion instrument of the orchestra and it belongs to the membranophone subfamily, being one of the Definite pitch instruments of the section. It has large bowl made of copper and the open top of that bowl is covered by calf or goat skin stretched, called vellum. They have a tuning pedal, which tune the timpani up, increasing or decreasing the tension of the vellum. The number of Timpani played in a piece fluctuate between 2 and 5 and they have different sizes, from 52 cm (piccolo) to 76 cm of diameter (bass).
The Timpani are played with Mallets, which are struck on the vellum. There are different kinds of mallets and they can be made of wood (hard), cork (soft), flannel or hard felt. Depending on the mallet the Timpani will sound different. They are pitched in the key of C, notated in bass clef and their sound range goes from B1 to C4. The timbre is determined by three factors: what the mallets are made of, where the mallet is struck and how hard the mallet is struck. The soft mallets get a dark sound, whilst the hard mallets are more brilliant and definite. Their sound could be dull, deep, heavy, powerful, resonant, dry and hollow, depending on the way they are played.