The carillon is the largest concert instrument in existence. The accepted international definition of the carillon is: A musical instrument which consists of at least 23 fixed carillon bells (almost two octaves) arranged in a chromatic series and played from a keyboard that permits control of expression through variation of touch.
The National Carillon in Canberra has 55 bells, the War Memorial Carillon in Sydney has 54 bells and the Bathurst War Memorial Carillon has 47 bells.
For more details on the three Australian carillons, and a general discussion on composing techniques, follow the link below.
Composing for the Australian Carillons
The carillon is the largest concert instrument in existence and belongs to the percussion family. The challenge of playing and composing for the carillon is that once a bell is rung it cannot be stopped. No damping is possible and the hum tone resonates for an extended amount of time.
The Bourdon is the largest bell in a carillon and sounds the lowest note. The Bourdon for the National Carillon is F#, for Sydney University the Bourdon is G, and for Bathurst, the Bourdon is C.
Carillons range in size from almost two octaves to over six octaves or from a minimum of 23 bells to as many as 77. Most contemporary carillon music, and much historic music, is written for carillons with a range of four or more octaves. Almost all carillon music can be played on such an instrument.