The Gamelan Si Betty, built in 1979 by Lou Harrison and William Colvig, was named for its benefactor, Betty Freeman. It is modeled on the court gamelan of central Java -- especially Kyai Udan Mas at U.C. Berkeley -- and is perhaps the largest American-built gamelan in terms of numbers of instruments. It accommodates over 30 instrumental players, as well as vocalists.

Si Betty's instruments, like those of its Javanese counterparts, are divided into two sets, one tuned in 5-tone slendro, the other in 7-tone pelog. Both scale systems of Si Betty are realized in just intonation, and were chosen after Lou Harrison sought approval from the Javanese master K.R. T. Wasitodipuro.

These photos were taken by Jody Diamond as the group rehearsed for a performance at the Cabrillo Music Festival in 1982. Lou Harrison is the white-bearded gentleman in the plaid shirt.