In the beginning of XX century the Gramophone developed by Berliner required large horn to amplify the recorded sound. The large horns had good performance but they were clumsy. In order to overcome such annoying condition, around 1905 the manufacturers launched in the market the fold horn concept in such way it
Fig 339 - The gramophone.
could be assembled inside the sound reproducer cabinet. Further to the aesthetical and practical aspects involved, this new type of sound reproducer had another advantage since the cabinet’ doors could be used as a kind volume control.
In the early Gramophone machines models the disc were purely hand operated and so it was quite difficulty to keep constant the recorder speed at 70-rpm. Later on, the new reproducers were supplied with a disc movement by winding motor, provided with an ingeneous centrifugal force operated principle mechanical device in order to keep the machine speed stable.
Originally the manufacturers chose the 70-rpm either to improve the fidely of the sound as well as to become the machine suitable for a proper reproduction of the early disc two minutes elapsed time. Such recorder speed was kept for a while and later it was changed to 74, 82-rpm and finally standardized at 78-rpm. Fig 339
Around 1913, the engineers looked to replace the winding motor for an electrical one.
Fig 340 - The “orthophonic” victrola.

However, in the begining such new technological improvement was quite slow considering the high price of the electrical motor as well as that the electrical supply could not be found elsewhere.
In 1925, the company Victor talking Machine Company, launched in the market the “orthophonic” system. It was an advanced technological improvement as it replaced the former mica membrane diaphragms by the ones made with a more resilient material as Aluminium. The sound reproducers were still operating in the mechanical-accoustical concept but they used now an exponential fold horn.
In the early twneties the quality of sound reproductions was deeply improved either by the aforementioned innovation as well as the birth of the electrical recording.
Therefore in 1928, the valve amplifier required in the talking movies, changed drastically the quality of sound recording and playback and so the golden age of the mechanical-accoustical sound reproducers came to an end. Fig 340