Parts of the Speaker

The core structure of a loudspeaker consists of a number of parts, each of which plays an important role in the production of sound.

1. Magnet

All speakers contain a magnet, either a permanent magnet or an electromagnet. The function of the magnet is to form a stable magnetic field, leaving a circular gap in the field for the voice coil and diaphragm to move through. The electromagnetic field generated when the voice coil is energized interacts with the magnet's magnetic field to drive the voice coil to vibrate, which in turn drives the diaphragm to produce sound. The strength and material of the magnet directly affects the efficiency and sound quality of the speaker. 


2. Voice Coil

The voice coil is a cylindrical coil of thin copper or aluminum wire suspended between the poles of the speaker magnet. The voice coil is placed in a magnetic gap. When current flows through the voice coil, it generates a magnetic field based on the principle of electromagnetic induction, which interacts with the fixed magnetic field of the loudspeaker magnet to create attractive and repulsive forces. This force causes the voice coil to vibrate back and forth within the magnetic gap, while driving the diaphragm to vibrate in synchronization, ultimately pushing the air to form sound waves. The diameter, number of turns, and material of the voice coil affect the sound quality, sensitivity, and power handling of the speaker.


3. Diaphragm

Diaphragm is a lightweight conical membrane, usually made of paper, plastic, metal or composite materials. Its function is to convert the vibration of the voice coil into air vibration (sound waves), so that the sound spread to the outside world.

When the voice coil vibrates, it pushes the air to create air pressure fluctuations, which are further amplified by the diaphragm and spread outward, eventually being picked up by our ears. The material and shape of the diaphragm have a significant effect on the clarity, frequency response and distortion of the sound.

♦ Harder materials (e.g. metal, ceramic) help to minimize high frequency distortion and improve resolution.

♦ Softer materials (e.g., paper, composite fibers) are better suited to provide a warm, natural tone.

The structural design of the diaphragm determines the speaker's performance in different frequency ranges, so different types of speakers use different diaphragm materials.


4. Spider

Spider is a wavy, flexible material located underneath the voice coil, usually made of cloth or composite fibers. Its role is to allow the voice coil in the vertical direction to stabilize the movement, while providing the appropriate rebound force to ensure that the voice coil can follow the audio signal vibration.


5. Surround

Surround is a ring of elastic material around the periphery of the diaphragm, usually made of rubber, foam or fabric. It allows the diaphragm to vibrate freely while limiting its range of motion to prevent deformation or damage.


6. Frame / Basket

The frame is a part of the speaker's enclosure that holds and supports the internal components. It is usually made of metal or high-strength plastic, to ensure that the speaker structure is stable and not affected by the external environment.


7. Dust Cap

The dust cap is located in the center of the diaphragm and is usually a raised circular cap. Its function is to prevent dust from entering between the voice coil and the diaphragm, while enhancing the high frequency response to a certain extent.