Fig. 322 - The phonographic industry.

The amplifying valve and the microphone dramatically changed the sound reproduction as already seen in chapter 7. In the early thirties, further to radio as a source of entertainment, the sound reproduction for domestic application was closed up to the phonographic record, an evolution of the Edison tin foil phonograph.
Originally, the machines for domestic reproduction of the early phonographic records used the mechanical-acoustical concept, which soon were replaced by the ones using amplifying circuits. Even considering such technological advancement for the epoch such so primitive machines and recording media had poor sound quality.
Around 1946, the so many technological innovations introduced in the electronic science by the war effort, pressed the industry to carve out new market opportunities and soon giving birth to the domestic audio: a compromise between advanced circuit topology apparatus and high quality sound media. Fig 322