Speaker operation can be hard to comprehend at first. However, once you break down a speaker into its component parts, it can be much easier to see how the parts fit and work together to create sound.
Speakers are based on an old design, which dates back as far as 1876, when Alexander Graham Bell got a patent for the first loudspeaker. [source]
Although speakers have been advanced and developed over the decades, the vast majority of speakers on the market operate in the same way, although they may look dramatically different.
A speaker works by taking an input voltage (your audio signal), and passing it through a voice coil in a magnetic field which oscillates. This movement causes the speaker cone to move, which creates the sound we hear.
This is a brief overview of how a speaker works, but in this article I will dig deeper into speaker operation, explaining how the component parts of a speaker work together to create sound.
I will cover:
- How do speakers work step-by-step?
- What are the parts of a speaker?
- What are the three main parts of a loudspeaker?
- What makes a speaker loud?
- What makes a speaker sound good?
How Do Speakers Work Step By Step?
The following steps explain how a general speaker works in a step-by-step process.
Although each of these points can be expanded and the physics explained in much greater detail, in the interest of simplicity, I have kept my speaker operation explanation to a simple step-by-step overview.
1. Connect The Audio Signal To The Speaker Terminals
When you connect your input audio signal to the speaker terminals, you are applying a voltage to the speaker terminals.
The speaker terminals are connected to the speaker voice coil.
The audio input signal flows through the speaker terminals and through to the speaker voice coil.
2. The Voice Coil Oscillates In The Magnetic Field
A speaker voice coil is a length of copper wire, wound around a cylinder called a former. This former can be card, paper, or something more robust, such as thin aluminium.
This copper voice coil is suspended in a magnetic field.
Because the voice coil with voltage flowing through is suspended in a magnetic field, it will oscillate. This is the fundamental operation of an electric motor.
Any current-carrying coil when placed in a magnetic field will create a force.
Because the input signal is AC (alternating current), it will cause the voice coil in this magnetic gap to oscillate up and down.
3. The Speaker Cone Moves
The speaker voice coil is glued to the speaker cone.
As the voice coil oscillates up and down in response to the input signal, in return, it oscillates the cone at the same frequency.
4. Sound Waves Are Produced
When the speaker cone moves, it will move the air molecules in contact with the speaker cone.
This will result in a sound wave propagating out through the air.
It is these sound waves that will reach our ears, which we hear as sound.
What Are The Parts Of A Speaker?
The above description gives a basic overview of how a speaker works; now let us dig deeper into the component parts of a speaker to see how they connect and work together.
- Speaker Terminals
- Voice Coil
- Speaker Motor Assembly – Magnet / Frontplate / Backplate / Pole Piece
- Speaker Suspension (Spider)
- Speaker Cone
- Speaker Dust Cap
- Speaker Surround
- Speaker Frame (Basket / Chassis)
1. Speaker Terminals
Speaker terminals are the connection points between the speaker and the audio signal source. They act as a gateway for electrical energy to pass through from the audio source to the speaker.
The terminals typically comprise two metal posts or binding posts, either with threads for attaching spade lugs or banana plugs or with holes for inserting bare wire.
2. Voice Coil
A speaker voice coil is an electromagnet that is the principal component of a loudspeaker, responsible for converting electrical audio signals into sound.
It comprises a coil of wire wound around an aluminium former, and when connected to an amplifier, electricity runs through the coil and creates a magnetic field.
This magnetic field interacts with the permanent magnet in the speaker, pushing and pulling it back and forth to create sound waves.
The bigger the voice coil, the more air can be moved and therefore the louder the sound produced by the loudspeaker. Therefore, larger speakers with bigger voice coils have greater audio output.
In addition to being found in loudspeakers and other audio equipment, voice coils are also used in many control systems, such as robotics, medical imaging devices, and linear motors.
3. Speaker Motor Assembly
A speaker motor assembly consists of several key components: a magnet, front plate, backplate, pole piece, and voice coil.
The magnet creates a powerful yet stable magnetic field for the voice coil to move in response to an audio signal.
The front plate is secured to the magnet, which is secured to the backplate. These surrounding steel components help to focus the magnetic field on the voice coil.
These components are specifically designed to ensure the magnet flux is highest in the region next to where the voice coil sits.
When a voltage (your audio signal) flows through the voice coil, as it is suspended in this magnetic field, it will oscillate up and down.
4. Speaker Suspension (Spider)
A speaker suspension, also known as a spider, is an important component of a speaker motor assembly.
Its primary purpose is to keep the voice coil centred and provide mechanical support for the cone of the speaker. Typically, it is made from a non-metallic material such as plastic or cloth to reduce harmonic distortion.
The suspension also provides a damping effect. This is important for preventing the speaker cone from moving too quickly, as this can cause damage to its components.
The suspension also allows the voice coil to move freely within the gap of the magnetic field so that it can generate sound properly.
5. Speaker Cone
The speaker cone is connected to the voice coil and converts electrical signals into sound. Its shape and material are key factors in determining a speaker’s overall sound quality.
As the voice coil oscillates, it causes the speaker cone to oscillate, which consequently produces sound waves. By changing the shape, size and material of the cone, different tones can be generated.
The speaker cone is typically made from paper or plastic. Paper cones are lightweight, flexible, and produce good sound quality, while plastic cones tend to generate higher frequencies with greater clarity.
A cone typically contains a rigid dust cap at its centre, which helps prevent airborne particles from entering the magnet structure and also provides structural support to the centre of the cone. It will also have a lightweight circumferential surround, which allows the cone to move freely as it produces sound.
6. Speaker Dust Cap
A speaker dust cap is a very important component of a speaker as it helps keep the cone and its parts safe from dust, dirt, and other elements that could cause damage over time.
The dust cap is typically made of cloth, paper, or plastic and is usually attached to the centre of the cone. It serves as a protective barrier to keep dirt and debris from entering the speaker’s interior parts.
The material of the dust cap also helps to dampen any resonance that is created when the cone moves back and forth, helping to replicate a more natural sound.
It’s important to ensure that your speakers are properly sealed to protect them against dust, dirt, and other potential hazards.
To learn more about speaker dust caps, check out this article which covers the topic in greater detail:
7. Speaker Surround
A speaker surround is a type of suspension system used in loudspeaker drivers to hold the cone in place and allow it to move freely. It usually comprises a flexible material, such as rubber, foam, or cloth, that is connected around the edge of the speaker cone and then attached to the frame.
Speaker surrounds help reduce distortion by allowing sound waves to travel evenly across all areas of the cone, producing a more accurate audio reproduction.
When designing speaker surrounds, loudspeaker design engineers will aim to create a surround that has enough excursion to ensure that the surround can move far enough to allow the cone to move adequately to produce sound.
In addition, surrounds will be designed to have “linear” motion. This means that the surround will move equally and similarly in the positive and negative direction to ensure that sound is reproduced accurately.
The surround should also be securely attached to the speaker frame and cone so that it does not move excessively or become detached during operation.
Finally, speaker surrounds should be designed with enough flexibility so that they can absorb any vibrations from the speaker cone and prevent them from entering other parts of the speaker system. This helps reduce distortion, allowing you to enjoy a much more accurate and enjoyable audio experience.
8. Speaker Frame (Basket / Chassis)
A speaker frame, also known as a basket or chassis, is one of the main components of a loudspeaker system. It is a metal or plastic housing that houses all the other parts inside the speaker system.
The frame holds and supports the speaker cone, magnet assembly, suspension system, and dust cap in place while providing the necessary structural rigidity to ensure the speaker system operates properly.
The frame also helps protect the other components of the speaker from physical damage and provides a solid platform for mounting and securing them in place. It’s important to use a strong, high-quality material when constructing frames, as they have to be able to support heavy loads such as large magnets and powerful amplifiers.
In addition, the frame must be designed with enough strength to withstand any vibrations that may occur during operation. This helps reduce distortion and provides a clean, accurate sound reproduction. A good speaker frame should also have an attractive design, as it is usually visible when the speaker system is mounted in the room.
Overall, the speaker frame is an essential component of any loudspeaker system, and it’s important to make sure it is well-built and designed for optimal performance.
What Are The Three Main Parts Of A Loudspeaker?
Given all these components of a speaker, you could argue that the three main parts of a loudspeaker are the cone, voice coil, and magnet.
It is the combination of these three components that make a speaker work and produce sound. All the other parts are structurally present to aid the operation of these three parts.
The cone is the component responsible for converting an electrical signal into acoustic energy. It is typically made of lightweight material, such as paper, plastic, or aluminium, that vibrates in response to an electrical signal.
The voice coil is a small coil of wire that is connected to the cone and acts as an electromagnet. When an electrical current flows through it, the voice coil produces a fluctuating magnetic field. This magnetic field interacts with the permanent magnet in the loudspeaker to cause the cone to vibrate and create sound waves.
The permanent magnet is a stationary magnetic device that helps to intensify the fluctuating magnetic field created by the voice coil. It also helps to push and pull the cone in response to shifts in sound frequency.
Together, these three main parts of a loudspeaker work together to convert electrical signals into acoustic energy. The cone vibrates, producing sound waves that are amplified by the voice coil and magnet. This allows us to receive the audio signals we hear from loudspeakers.
The quality of sound produced by a speaker is highly dependent on the design and materials used for each part. Different types of cones, voice coils, and magnets may be used to create a unique sound profile for different applications.
What Makes A Speaker Loud?
1. Increase Power
Speakers can be made loud by increasing the power, or wattage, that is sent to it. This can be done by using an amplifier, which takes the electrical signal from a sound source and amplifies it before sending it to the speaker.
2. Bigger Cone
Additionally, loudspeakers with larger cones provide better sound projection and, therefore, louder audio compared to small cone speakers.
3. Multiple Speakers
Lastly, using multiple speakers arranged appropriately will also increase volume levels overall.
You can also experiment with speaker location within a room to ensure that it is in the optimum position to produce the best sound output.
What Makes A Speaker Sound Good?
What makes a speaker sound good is largely dependent on the quality of its components and design. High-quality speakers typically have higher-grade materials used in their construction, such as treated paper or woven fabrics for cones, stronger magnets and better voice coils.
Additionally, the enclosure of the speaker can also affect the sound quality produced by controlling how much of the back wave radiates away from it.
Properly tuning a speaker system will help to ensure that you get the maximum performance out of your setup and can greatly improve sound quality.
Moreover, using an equalizer or amplifier will help fine-tune a system to fit specific needs, whether it is for music production or home theatre systems.
Finally, proper placement within a room can also help with achieving great sound from your system.
Final Thoughts
In conclusion, speakers are made of many components that work together to create sound. The three main parts of a loudspeaker comprise the cone, voice coil, and magnet, which vibrate in response to an electrical signal.
Power can be increased using amplifiers or bigger cones, while multiple speakers will help increase volume levels.
Additionally, high-quality materials such as treated paper for cones and stronger magnets also contribute towards better audio quality.
Finally, proper tuning with equalizers or amplifiers along with placement within a room are important factors too when it comes to achieving great sound from your speaker system.