This Loudspeaker Model C2 form C. Manufactured in 1923 by B.T.H. was one of the first to enable other family users to hear the wireless. Up until its development listening to the radio was a rather solitary practice for the person lucky enough to have possession of the headphones. Using a headphone earpiece hidden in the moulded bakelite base, the acoustic properties of the horn produced an amplified sound that the rest of the family could hear. This type of loudspeaker soon became very popular and thousands were sold.
A control knob mounted underneath the base enabled adjustment of the diaphragm distance from the magnetic coils that acted as a primitive form of Volume control.British Thompson-Houston Co. Ltd. also manufactured Valves under different brand names like Mazda.