 Oberheim was attending a class during his last semester at UCLA when he met and became friends with trumpet player Don Ellis, and keyboardist Joseph Byrd of the band The United States of America, who were attending the same class.Oberheim stayed in touch with both Ellis and Byrd after leaving UCLA, and ended up building an amplifier for Ellis to use for his public address system.Oberheim also built guitar amplifiers for The United States of America, and their lead singer Dorothy Moskowitz asked him to build a ring modulator for the band (Joseph Byrd had used one while a band member, and Moskowitz wanted one for the band's new keyboardist, Richard Grayson).