Leo Fender began building guitar amps before he started manufacturing guitars.

The first of these amps were the K&F models, which were produced between 1945 and 1946. The first line of amps was the Woodie amps that were produced until 1947. These were replaced in 1948 by the more popularly known Tweed line of amps. These amps derived their name from the tweed covering used by Fender until 1960; except for the Champ series, which continued to be used it until 1964.