Cellovox was an external speaker manufactured in the 1920s, during the early days of electrodynamic speakers. It belonged to the category of pressure speakers and featured a large Bakelite sound horn, reminiscent of gramophones of that era. Its design utilized a simple electromagnet to move a diaphragm within the sound horn.
This external speaker was primarily used with early radio receivers, which either lacked built-in speakers or only had weak ones. It connected to the radio via two banana plugs, interfacing directly with the receiver's output circuit, where a small amount of direct current flowed.
The Cellovox is a classic horn speaker, distinguished by its characteristic appearance that graced many households during the interwar period.