In a passive loudspeaker system the low-level audio signal is first amplified by an external power amplifier before being sent to the loudspeaker where the signal is split by a passive crossover into the appropriate frequency ranges before being sent to the individual drivers.
A landform is a natural feature of the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography.
A natural landform is a feature of the land that has been created by nature, not by humans. Mountains, cliffs, beaches, islands and lakes are all natural landforms. Australia has many special landforms. People from all over the country and all over the world like to visit them.