title: Fender amplifier
context: Leo Fender began building guitar amplifiers before he started manufacturing electric guitars. The first of these were the K&F models, produced between 1945 and 1946. The early K&F and Fender amplifiers relied upon vacuum tube circuitry, with the company adding solid-state models in the late 1960s.
question: When did Fender produces their first guitar amp?
answers: between 1945 and 1946