Before the 1920's when inventors discovered a means by which sound waves could be recorded & reproduced electrically, the only way of hearing the sound on a record was a needle attached to a horn which was mounted on top of the record player. The needle vibrated as it moved over the grooves in the record and the sound was amplified directly by the horn.
Around 1924, two Americans, E.W. Kellogg and C.W. Rice invented the first loudspeaker without a horn. The new system they produced is still the fundamental basic design of modern day loudspeakers.
The construction of a loudspeaker consists of a circular cone or diaphragm which is held by suspensions around the edge and near the centre. At the centre of the cone is the cylindrical former, this has the voice coil wound on to it. The voice coil and the cylindrical former are positioned between the poles of a magnet. The coil receives a signal which exerts a force and causes the cone or diaphragm to move. This forward and backward movement then generates sound waves.
Modern HiFi speakers are very sophisticated and are usually `2-way' or `3-way' speaker systems, that is 2 or 3 speakers in a single enclosure. The 3 speakers in a `3-way' system are the `woofer' for bass, the `squawker' for mid-range and the `tweeter' for treble. The incoming audio is distributed evenly to each speaker via an electronic circuit called a `crossover network' built into the speaker enclosure.
