Cellovox was among the manufacturers of external speakers in the 1920s, an era marked by rapid development and expansion of both radio broadcasting and radio technology. At that time, radio receivers were not yet commonly equipped with built-in speakers, making external speakers an essential accessory for enjoying broadcasts.
Cellovox speakers fell into the category of horn or diaphragm speakers. They used an electromagnetic coil to vibrate a diaphragm or sound throat, operating on a principle similar to that of telephone earpieces—but on a significantly larger scale.
The design of these speakers was often decorative, featuring stylish combinations of metal, Bakelite, or wooden elements. These designs were made to complement radio receivers and enhance the aesthetic of homes during the era.