Can you imagine a phone without a built-in speaker or a music concert without those giant speakers? No, you can't because it will be pointless to buy a phone that doesn't produce sound or go to a concert where the performer is only singing to the first row. Speakers are as important for electronic and digital devices as these devices are for our daily lives. And, do you know what's at the heart of your smartphone's speaker? A minuscule magnet. Without a magnet at the center of it, a speaker will not be able to convert electric signals into mechanical signals i.e. sound.
A quick recap of the history of speakers; Johann Philip Reis created the first-ever sound transmitter in 1861 using a coil and a diaphragm that could convert sound waves into electrical signals. Later in 1876, using magnetic coils to transmit sound, Alexander Graham Bell invented the first telephone that had practical uses. In the 20th century, permanent magnets replaced electromagnets revolutionizing the efficiency and compactness of speakers. In the 1980s, Neodymium (NdFeB) took the world of speakers by storm with its unparalleled magnetic strength and compactness.
Fast-forward to 2024, and we have come a long way from coils and diaphragms. Most of the sounds you hear every day come from speakers, but have you ever stopped and wondered how important magnets are for speakers? Well, let's find out.
What is a Magnet?
Simply put, a magnet is a material that generates an invisible field i.e., a magnetic field. The magnetic field is a strong force that can attract other materials such as iron or cobalt or repel them. Based on their ability to produce a magnetic field, here are the two main categories of magnets.
Permanent magnets – a permanent magnet is a magnet that has a permanent magnetic field. It doesn't require any external force to produce a constant magnetic field. Examples of permanent magnets include Neodymium, iron oxide, and barium ferrite.
Temporary magnets – temporary magnets are magnets that can produce a temporary magnetic field only when they are under the influence of another magnetic field. So, they require a foreign magnetic field to show magnetic properties.
A stable, constant, and strong magnetic field is essential for the operation of a speaker. This is why permanent magnets are of paramount importance for speakers.
Science of Sound
Another aspect that you need to understand to comprehend the operation of a speaker better is Sound. It is a form of energy that is created by the vibration of particles in a medium i.e. air or water.
A vibrating object creates pressure waves that pass through the medium and result in sound waves. Sound waves after reaching our ears cause our eardrums to vibrate which our brain interprets as sound enabling us to listen to music or other people's voices.
Following this natural phenomenon, speakers convert incoming electric signals into mechanical energy creating sound waves. A magnet plays a huge role in the movement of the diaphragm in a speaker and precise sound reproduction. A diaphragm creates sound waves when it vibrates.
How Do Speakers Work?
A voice coil, a permanent magnet, and a diaphragm are the three key components in the speaker that play a key role in sound production. Here's how speakers work utilizing these components.
Voice coil- a speaker's operation starts with the induction of an electric current through the voice coil which is a coil of wire. In response to the electric current flowing through it, the voice coil starts creating a magnetic field. The voice coil's position in the speaker is also crucial for precise sound reproduction. It is placed in a permanent magnet's magnetic field and the interaction of these two variating magnetic fields takes the process of sound production further.
Permanent magnet as we already know, a constant magnetic field is a characteristic feature of a permanent magnet. A permanent magnet is selected based on the strength of its magnetic field which is also an important factor for the speaker's operation. When the magnetic fields created by the permanent magnet and the voice coil coincide, they cause the voice coil to move rapidly resulting in the movement of the diaphragm.
Diaphragm- the diaphragm is attached directly to the voice coil and as the voice coil moves in response to the interaction between the two magnetic fields, the diaphragm which is a thin and flexible membrane also moves back and forth. This movement of the diaphragm starts a cascading flow of the air creating sound waves.
And that's how a speaker creates sounds in response to an electric signal. Again, the position of the voice coil and the strength of the permanent magnet's magnetic field are vital for the production of sound waves that mirror the electric signals provided to the speaker in the first step. A speaker with a well-designed layout and the best quality components can easily convert electric energy into sound energy with minimal distortion.
Why Are Magnets Essential in Speakers?
Here are the reasons why magnets are essential in speakers, some of which you already know from the previous context.
Creation of a magnetic field
The most important and obvious reason is the magnet's ability to create and constantly provide a magnetic field for sound production. The magnetic field created by a permanent magnet is essential for coil movement which is a crucial step in the speaker's operation.
Enabling diaphragm motion
The diaphragm's movement is responsible for the creation of sound waves and it can only move if the magnet provides a magnetic field for the coil to move as the diaphragm is attached directly to the coil.
Conversion of electrical energy into sound energy
Through a cascade of operational steps in the speaker, the magnet helps create a motion which in turn converts electric signals into mechanical energy resulting in the creation of sound waves.
Controlling sound reproduction
Precise movement of the diaphragm in sync with the electric signal is important for the production of accurate, clear, and undistorted audio. The magnetic field's strength and consistency provide control over precise sound reproduction.
Influencing the quality of sound
The size and strength of the magnet also affect the quality of sound produced by the speakers. As the size and strength of a magnet increase, so does its ability to produce powerful sound, especially at lower frequencies.
Determining the volume of the sound
The strength of the magnet is also responsible for the production of louder sounds. Strong permanent magnets move the diaphragm more rapidly which enhances the volume of the sound produced.
Impacting speaker's size
The size of the magnet is also important for the size of the speaker. Larger and stronger magnets are used for large speakers to create more powerful sound. For smaller and compact speakers like headphones or portable speakers, smaller and stronger magnets such as Neodymium are used.
Balancing frequency response
The frequency response of a speaker is also dependent on the size and strength of the magnet. Larger magnets are usually very effective for producing low-frequency sounds while smaller magnets can handle high frequencies more efficiently.
Ensuring long-lasting performance
Neodymium and ferrite magnets are examples of strong permanent magnets. They ensure the production of strong and consistent magnetic fields for longer periods of time. This enhances the durability of the speaker and ensures long-lasting performance without seeking regular maintenance and/or replacements.
So, a powerful magnet is crucial for a speaker to perform at its best, have a lasting life, and produce powerful sound of the best quality over different frequency ranges.
Types of Magnets Used in Speakers
Different types of speakers utilize different types of Magnets based on their sizes, strength, price and other factors. The most common types of magnets are Ferrite Magnets, Neodymium Magnets and less commonly, Alnico Magnets. Here is a detailed explanation of every type of magnet used in speakers.
Ferrite Magnets
Ferrite Magnets are manufactured using a ceramic compound of iron oxide that is mixed with other materials such as barium or strontium carbonate. They are the most commonly used speakers because they offer good magnetic strength and are affordable.
Advantages
Here are the advantages of Ferrite Magnets.
Affordability – ferrite magnets are readily available because they are not as expensive as other magnets to mass produce. This makes them a decent choice for budget-friendly speakers of good quality and larger sizes.
Long life - these magnets offer long-lasting performance because of their ability to resist corrosion, rust, humidity, and high temperatures. They can withstand high temperatures without losing their magnetic capabilities for longer.
Easy accessibility – iron oxide and other materials used to manufacture ferrite magnets are abundantly available and because of that, these magnets are cost-effective and easily accessible.
Disadvantages
Here are the disadvantages of ferrite magnets.
Lower magnetic strength- ferrite magnets exhibit lower magnetic strength than neodymium magnets. This makes them less suitable for smaller speakers.
Bulky- to produce powerful sound, ferrite magnets need to be heavier to produce the required magnetic strength.
Not suitable for smaller speakers- due to lower magnetic strength, ferrite magnets are not suitable for smaller and compact speakers.
Neodymium Magnets
Made from an alloy of Neodymium, iron, and boron, Neodymium magnets exhibit the most powerful magnetic strength even in small sizes. These magnets are the ideal choice for smaller, compact, and high-performance speakers such as headphones, earphones, and compact Bluetooth speakers.
Advantages
Here are the advantages of Neodymium magnets.
High magnetism – neodymium magnets are the most magnetically charged magnets as they can create much stronger magnetic fields than ferrite and other magnets. Because of their high magnetism, neodymium magnets are able to deliver high-quality sound even in smaller speakers.
Lightweight – a minuscule neodymium magnet can deliver a much stronger magnetic field strength than ferrite and other magnets. This is why they come in smaller sizes and they are easy to mend into products such as Custom Circle Magnets and Bracelet magnet balls.
Sound reproduction- neodymium magnets provide better control over the movement of voice coil and diaphragm making them the best choice for accurate and cleaner sound reproduction. They are ideal for high-performance audio equipment.
Disadvantages
Here are the disadvantages of Neodymium magnets.
Costly – neodymium is a rare-earth-element which means that the cost associated with the production of these magnets is high. The high cost of these magnets is most likely responsible for the high cost of speakers.
Prone to corrosion – unlike ferrite magnets, neodymium magnets are more susceptible to corrosion, rust, and humidity. If not properly coated with protective material, neodymium magnets can lose their magnetic properties, especially in humid and corrosive environments.
Sensitive to heat – higher temperatures may also cause neodymium magnets to lose their magnetic strength. This means that these magnets cannot be used in audio equipment that is meant to be used in extreme heat conditions.
Alnico Magnets
Made from an alloy of Aluminum, Nickel, Cobalt, and other elements like iron and copper. Once the industry standard, Alnico Magnets are now less common because of the popularity of ferrite and neodymium magnets.
Advantages
Here are the advantages of Alnico magnets.
Alnico Magnets create a more stable magnetic field which contributes to smoother sound production.
Alnico Magnets are highly resistant to heat which means that they can perform efficiently in high heat conditions.
Alnico Magnets are known for their natural sound reproduction. This property makes them desirable for certain people.
Disadvantages
Here are the disadvantages of Alnico magnets.
Because of the cost of elements like Cobalt, the production of these magnets is costly, which makes the final product pricier.
Alnico Magnets exhibit lower magnetic strength than even ferrite magnets which means that much larger sizes of these magnets are required to create the required magnetic strength.
Alnico speakers are less common because of the popularity and cost-effectiveness of other speakers made with ferrite or neodymium magnets.
Conclusion
In a nutshell, magnets are necessary for speakers because they provide the magnetic field vital for the conversion of electrical energy into sound energy. Magnets create a magnetic field that interacts with the magnetic field of the voice coil. In response to that the voice coil moves which makes the diaphragm move. The movement of the diaphragm results in the creation of sound waves. Neodymium Magnets are the most popular type of magnets because of their high magnetism and strength. They come in different sizes and shapes such as Arc magnets or pushpin magnets. Ferrite magnets also offer decent magnetism and they are cheaper. So, choose your magnets wisely the next you go magnet hunting.