There may in fact be more than forty different types of gamelan in Bali, each one serving a different function. Here’s a very rough guide on which one’s for which:
1. Dewa Yadnya (for the Gods, e.g. temple ceremonies)
In South Bali, it is most common to use a large gong ensemble known as Gong Kebyar or sometimes Gong Gede. Gender Wayang may also be played on a smaller pavilion in the inner sanctum. A number of villages in South Bali also have either a five- or seven-tone Semara Pagulingan and this is often played alternately with or replaces the more modern Gong Kebyar. I’ve also seen gamelan normally associated with cremation ceremonies such as Gambang or Luang played at temple ceremonies around Denpasar but never Angklung.
Once you get to Ubud or go East to Karangasem, it seems that anything goes, perhaps excepting the more secular bamboo gamelan ensembles. Angklung is common and the stately Gambang is seen accompanying ritual dances in some villages in Karangasem. Selonding is found in many ancient villages in the Bangli and Karangasem region.
2. Manusa Yadnya (for people, e.g. toothfilings, weddings, 3-month birthdays, receptions)
Gender Wayang is most common here – being an intimate ensemble, it is suited to the earthy wedding ritual. At larger weddings, wealthier families will commission a delicate Semara Pagulingan which may accompany refined court dances such as Legong and Jauk in the early evening. Joged Bumbung is used to liven up receptions.
3. Pitra Yadnya (death rites)
There is a special gamelan for every stage of the process of death rites. Gender Wayang, Angklung and Gambang are used in South Bali all the way through, depending on the caste (or the wealth) of the family of the deceased. At the final Mukur ceremony, a Saron or Luang ensemble will play haunting music to attract the souls to the ceremonial ground.
