|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