Principle:
The principle most commonly used and applied to the speakers is based on the laws of Biot-Savar-Laplace, introducing the interaction between the magnetic field and electric current.
Things to remember: electricity and magnetism are always related
The passage of current through a conductor creates a magnetic field
For consistent variation of the magnetic field creates an electric
current
For consistent with this principle, is the most important and causes the transducer. In fact, an object crossed by a stream, and placed in a magnetic field, has the ability to move in proportion to the intensity of current passing through it. The parameters to be considered is the value of this field and solid conductor tension or intensity. Each of these quantities is related to another by the impedance through classical Ohm's law.
By applying a voltage between terminals of the coil is traversed by a current consistent I.
By construction each conductive element dL is normal to the axis of the magnet. As the magnetic field is radial, this element is subjected to a force dF = I dL ^ B (Laplace force) parallel to the axis. For reasons of symmetry, the resultant of forces acting on the coil is axial.
The moving assembly (coil + membrane) is subject to the following forces:
* The strength of the connection back to the cone.
* The Laplace force.
* A virtually friction force proportional to velocity.
If the coil is energized by a solenoid voltage, the membrane moves as a rigid piston that drives the air and generates a sine wave sound.
It should be noted, in this case, it is desirable to fix the diaphragm to the magnet coil due to its weight. It is always about getting a membrane mobility as large as possible to get a wider range of frequencies.
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The practical realization of a speaker "effective" is difficult. The speaker idealtiene a curve with a pressure response and high frequency sound as flat as possible. Therefore the mechanical system is an equivalent system of oscillation of the first order to be recovered enough strength to have a flat response.
To arrive at a correct response across the range of the sound spectrum should involve several factors, with very different resonance frequencies and a filter system for handling the signal in terms of their frequency with the appropriate speaker.
Vibrating membrane also creates two sound waves in the opposite phase: the wave front and wave back.
To eliminate the back wave, the speaker should be placed in a box lined with an absorbent material, which also participates in the damping.
You can also use the speakers bass reflex wave to phase out the back and add to the wave before you leave.
