Project Description

The word “speaker” is the shortened form of the word “loudspeaker”, and it means that a device that converts electrical signals into sound waves that we can hear. A speaker has several components:

To be simplized the above, they are all components that convert electrical signals into sound signals for playback. From the analogy acoustic signal input into the voice coil, acting as alternate current, drive the voice coil move back and forth along the pole piece, through the speaker diaphragm movement to generate the acoustic wave.

Why do drivers come in so many different sizes? Because it is nearly impossible to make one piston driver that can reproduce sound waves over the entire 20 Hz to 20 kHz frequency range of human hearing. To produce low frequencies a driver needs to have a large diaphragm and enough mass to resonate at a low frequency. To produce high frequencies a driver needs to have a small diaphragm with a low mass. Obviously, these requirements are in opposition so drivers are usually designed to produce only a portion of the sound. This gives rise to multi-way speaker systems like the two-way system shown above. It uses a tweeter for the high frequencies and a woofer for the low frequencies.

Let’s separate the components by different functions:

Motor parts:

  • Pole Piece(Center Pole): The pole piece is connected to the back plate and extends the pole of the magnet; it extends into the center of the voice coil.
  • Magnet: provides a stationary magnetic field to oppose the alternating electromagnetic field of the voice coil and thereby cause the attached cone to move inward and outward.
  • Top Plate(washer): which provides another layer of decoupling between the stand and speaker.” And each part of the construction plays an important role in managing vibrations: the feet either couple or decouple the stand with the ground and the top plate does the same with the speakers.
  • voice coil(coil former): the coil of wire attached to the apex of a speaker cone. It provides the motive force to the cone by the reaction of a magnetic field to the current passing through it.
  • screen, vent(optional): some drivers include a rear vent to prevent pressure from building behind the cone in the magnet assembly and to provide cooling of the voice coil. A screen is usually provided to prevent debris from entering through the vent.
top plate, magnet, pole piece

top plate, magnet, pole piece

Diaphragm parts:

  • cone(diaphragm): the thin, semi-rigid membrane attached to the voice coil, which moves in a magnetic gap, vibrating the diaphragm, and producing sound.
  • dust cap(dust cover): a gently curved dome mounted either in concave or convex orientation over the central hole of most loudspeaker diaphragms. It protects the inner mechanics (such as the pole pieces and the voice coil) from small particles (which can cause rubs) and other contamination.

Suspension parts:

  • Spider(Damper/suspension): one of the most stressed parts for a loudspeaker, it function to provide suspension for the cone, and centers the voice coil in the voice coil gap. Besides, it is used to limit the inductor’s oscillation and the loudspeaker’s excursion without affecting the oscillation’s linearity.
damper of the speaker

damper of the speaker

Frame parts:

  • Basket(frame): also called the “frame” or “chassis”, provides a rigid structure to which the driver components are mounted.
  • Surround: The surround is the poly-foam, foam, butyl, accordion or a single cloth or “m” roll cloth ring that holds the cone and the basket together. It acts as a suspension system that works harmonically with the spider to bring the cone to its normal position between vibrations.

What makes one speaker better than another one?

If you’ve listened to more than one set of speakers, you probably find out that some speakers sound better than another one. Even if you understand the underlying technology & the above sturcture, it’s hard to explain why speaker X sounds better than speaker Y.

So, what makes one speaker better than the other one?

 

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