I’ll try and answer pretty simply for you now, how do PA speakers work?
From your iPod head phones, listening to your TV, right through to listening to someone speak to you on your phone there are speakers everywhere in our lives, not only the ones that blast loud music at you at concerts, festivals and at pubs and taverns.
Also when explaining how do PA speakers work, I’ll not only give you an idea about the parts that make up a speaker system, I’ll also give you a bit of an insight into how pretty much every speaker in your home works.
So here we go!
From as early as 1874 Ernst Siemens was the first to describe the moving coil transducer with a circular coil of wire which was in a magnetic field and supported so it could move axially, this formed the start of the current speaker setup as we know it.
He then filed for a patent for a magneto electric apparatus for obtaining the mechanical movement of an electrical coil from electrical currents transmitted through it in this same year, he also was granted this patent the same year although he didn’t use his device for audible transmission at all.
It was Alexander Graham Bell that did though and we all know he was the man who invented and patented the telephone.
So these were the beginnings of the speaker as we know it today, sure there has been some major technology advances in design and material but the theory of how the system works is in essence intact.
A speaker is made up of many parts that all work together to produce the sound we hear.
These are the parts that make up a PA Speaker:
- Electromagnet voice coil
- Dust cap
- Diaphragm speaker cone
Now to the juicy part of how all the parts above give you sound through your PA when you’re wailing out your tunes.
For a speaker to translate an electrical signal into a sound you can hear speakers contain an electromagnet and the electromagnet is a metal coil that creates a magnetic field when an electric current passes through it.
The electromagnetic coil generally behaves like a normal day to day magnet but has the ability to reverse the direction of the current flowing through it, this means it has the ability to change the coils polarity so the north end of the magnet can become south and vice versa.
The electromagnet is a coil of wire wrapped around a generally round piece of metal, this is usually the metal iron, and running an electrical current through this wire then creates a magnetic field around the coil and so magnetising the piece of metal it is wrapped around if it is not magnetised already.
This field acts like a normal magnet would and has a north and south end polar orientation, but the key is that this polarity, as I have said above, can be reversed when needed unlike a normal permanent magnet would behave, this is done by reversing the flow of current though the coil.
And this is what your sound signal is doing, it constantly is reversing the flow of the current through to the electromagnet coil in the speaker.
When you connect your speaker to your amplifier there is two inputs for the speaker, one is usually red and one black and they usually have a positive sign and a negative sign as well on them.
The amplifier is in essence switching all the time the electric signal between a positive and a negative charge on the red input wire to the speakers, this makes the current flow one way and then they other and this happens many times a second.
So to reiterate and also move into what happens in your speaker as above is a bit more theory and what is behind the concept of an electromagnet.
Inside the speaker is an electromagnet that is placed in the middle of a permanent magnet, the permanent magnet is in a fixed position and the electromagnet is mobile, as the signal comes through and the direction of the magnetic field is changed the electromagnet vibrates back and forth or up and down to be more precise.
The electromagnet is attached to the diaphragm speaker cone that is made up of flexible material and then amplifies these vibrations into sound waves and this is what we hear.
The frequencies of these vibrations govern the pitch of the sound that is being produced and their amplitude affects the volume of the sounds.
There are many different sized diaphragm speaker cones, strength of magnets, different size speaker boxes and all of these variations are used to produce different frequencies of sound that is required.
Also in regards to PA systems you have multiple different types of sounds that are needed from low down dirty bass frequencies up to the top end highs and these all need different types of amplifiers and EQ’s driving them with the correct speaker parts set up to give you the desired outcome in sound and also volume, the differences and possibilities when it comes to speakers big and small are endless.
So I hope this hasn’t been too hard to grasp the concept of how PA speakers work and now every time you see or hear a speaker working you will be looking at it and thinking about it in a completely different way.