Figure 5-5. Speaker pumping action creates air vibrations we hear as sound
a. Drivers are the part of the speaker that actually move air. Drivers can be designed to get
superior performance in the lower octaves (bass) or higher octaves (treble), usually not both. Most all
speakers are basically AC electric motors functioning linearly instead of by rotation. Speakers have
wire coils or another form of an electrical conductor hanging freely in the field of a permanent magnet.
(1) Electricity flows through the conductor and creates a magnetic field around the conductor
with a strength equal to the amount of electricity moving through it.
(2) If the current changes directions, the north-south poles of the magnetic field reverses
themselves with each current reversal. A permanent magnet's polarities remain constant.
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