The Leslie speaker was invented in Los Angeles by Don Leslie, from 1937 to 1940. He produced his first Leslie speaker on december 1940 and started marketing Leslies under the company name Electro Music. In 1965 the business was sold to CBS Musical Instruments and in 1980 CBS sold Electro Music to Hammond. Noel Crabbe, an Australian, took on Hammond and Electro Music in 1985. Don Leslie estimates that more Leslie 122s have been made than 147s, he states a couple hundred thousand.
Figures regarding other models are unknown.
Business ownership has changed hands at least four times since being established making manufacturing numbers unavailable.