A complete Javanese court-style gamelan actually comprises two sets of instruments, one for each tuning system (laras): sléndro (a five-tone scale) and pélog (a seven-tone scale).
Within each of these tunings are three pathet, a Javanese concept referring to both mode and mood. No two gamelans are tuned exactly alike; each ensemble is unique, and may often be given a name.
The layout of the gamelan reflects the role of the different instruments in the music.
In the middle of the gamelan, the ‘skeletal’ melody (balungan) is played on the bronze metallophones (saron family and slenthem).
The balungan is punctuated by the larger gongs (gong and kempul) and the horizontally-mounted gongs (kenong, kethuk and kempyang) at the back of the gamelan.
At the front of the gamelan a selection of more complex instruments embellish the melody
- the two bonang (double rows of gong chimes mounted on a frame)
- gendèr (multi-octave metallophone)
- rebab (two-stringed fiddle)
- gambang (xylophone)
- siter (zither) and
- suling (bamboo flute).
The voice is an essential element in Javanese gamelan: a complete ensemble also includes a male chorus (gérong) and solo female singer (pesindhèn).
The whole gamelan is co-ordinated by the drummer in the centre of the ensemble, playing a selection of double-headed drums (kendhang).