Speakers have magnets because magnets create an opposing magnetic field which results in vibrations which are the sounds we hear. Speakers convert electrical energy or electrical audio signals into mechanical wave energy or vibrations which is done by using electromagnetism to move the diaphragm within a magnetic field to produce sound.
Let’s explain a bit further. As you already know, for speakers to work, they need electric current.
This current goes through a coil in the speaker and creates a magnetic field. The speaker attached to the speaker creates another magnetic field that opposes the magnetic field created by the electric current going through the coil (and changing direction as it goes).
These opposing magnetic fields create vibrations in the speaker’s cone or panel (since the cone is attached to the magnets and coils).
These vibrations produce the actual sound we hear from our speakers. As you can imagine, the larger the magnet or the more current is supplied, the louder the sound from the speaker.
A Detailed Explanation of Why Speakers Have Magnets
For speakers to produce sound, they need to create audible mechanical vibrations in the air. That means they need something that can vibrate quickly when hit by electric signals. The vibrating item in a magnetic speaker is a diaphragm (or cone).
The diaphragm is a conical structure made up of a flexible material. When driven by a magnetic force (repulsion and attraction – we will explain this more), the diaphragm vibrates.
It’s attached to a coil placed near the magnet, to make it vibrate when an electric current passes through it.
The magnet allows the speakers to create mechanical vibrations (sound) by allowing the electric signals to interact with the magnetic field. When the electric signal going through the voice coil changes its direction, it creates a polar movement between the magnet and the speaker.
The magnet helps to create a magnetic field that creates sound vibrations when hit by electric signals. The signals cause fluctuations in the opposing magnetic forces between the magnet and the coil, making it move back and forth through the attached diagram.
The truth is, the type o magnet doesn’t even matter as speaker s use many different types of magnets. What matters is that the material can create a magnetic field strong enough to move they could. Since coils are normally small and lightweight, speaker magnets don’t need to be extremely strong. You can learn about speaker magnet strength here.
So, does that completely answer your question ‘why do speakers have magnets?’. If not, move on to the deeper explanation below.
An Even Deeper and more Scientific Explanation
As we already explained, magnetic speakers are made up of a permanent magnet and a magnet created by the coil as current goes through it (it is essentially an electromagnet).
These magnets work as a pair and interact with each other as two physical magnets would. The electromagnet is put in a magnetic field created by the physical magnet and as each produces its own magnetic fields, they oppose each other.
Just like two normal speakers, the positive pole of the permanent magnet attracts the negative pole of the electromagnet.
On the other hand, the negative pole of the permanent magnet repels the negative pole of the electromagnet and causes a shift in the magnetic forces hitting the voice coil.
The direction of the attraction and repulsion changes with the shift in the polar orientation of the electromagnet.
When the polar orientation switches, the alternating electric signal constantly pushes back the magnetic force between the permanent magnet and the voice coil.
This makes the coil rapidly vibrate back and forth, making the speaker cone move in different patterns. The coil movement then creates vibrations in the air, resulting in audio signals (sound is nothing but vibrating air).
The strength and frequency of the magnetic forces determine the distance and rate at which the voice coil moves. In other words, the magnetic forces regulate the vibrations created by the diaphragm.
This in turn determines the strength and frequency of the sound coming from your speakers. This is why you can use an electric current to control a speaker’s loudness.
So, the main purpose of the magnets is to make sure that the voice coil vibrates efficiently, as the magnetic field changes.
Without them, the coil would move in the same direction as the signal and just make a weird sound. It’s important to note that magnets themselves do not make the sound better, but they are a vital part of sound formation.
Their function is to produce opposing magnetic fields that move the coils to produce sound.
We have gone through a basic, long, and even longer explanation as to ‘why speakers have magnets’. Now, we hope you have learned and understood the importance of magnets in audio systems.
So, there you have it, the answer to the question ‘Why Do Speakers Have Magnets’. It’s simple really, the magnets produce opposing magnetic fields which then drive the cone which then produces sound. So, magnets are essential to the operation of speakers.
Can a speaker work without a magnet?
Yes. It is possible (usually in lightweight speakers) to achieve this by substituting the magnet for two coils.
Why Does a Speaker Need a Magnet?
There is an electrical current present in every amplifier (speaker) and a magnetic field is created when the current changes. Magnets are employed to create an opposing magnetic field that causes vibrations in the cone (or panel) of the speaker. The sound we hear is made up of these vibrations.
Do All Speakers Use Magnets?
Magnets are not used by all speakers. Magnets are employed only by magnetic speakers to generate mechanical vibrations (sound) by interacting with the magnetic field formed by pulsing electronic signals that travel via a coil suspended in the magnet’s strong magnetic field.
Which Type Of Magnet Is Used In Speakers?
Neodymium magnets are used in most speakers. They are highly powerful, relatively small permanent magnets made from an alloy of neodymium, boron, and iron which are highly magnetic and really difficult to demagnetize.
Why Do Speakers Have Big Magnets?
The bigger the magnet, the louder the sound. Since magnets determine the strength of a speaker’s driving force, small magnets are used in smaller speakers and produce a weaker sound than larger magnets are used in larger speakers which will make for producing a much louder sound. In summary, one of the most integral elements that make sure a loudspeaker is able to sound louder is the size of the magnet.
So basically, as you have learned, speakers have agents because the agents create the magnetic field necessary to move the coil and cause vibrations or sound.
This means speaker agents are essential and speakers would certainly not work without them.
Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics.