I know what makes a computer tick. I’ve got a fairly good understanding of who an airplane can take to the skies. And on a basic level, I can even explain how nuclear fission works.

Loudspeakers, on the other hand, is beyond my comprehension. Mechanically, they are so amazingly simple, yet what they are capable of is remarkable. Speakers can create every sound that ever was and ever will be simply by reacting to a varying electrical current that makes a membrane push air around!

Think about that for a second. Or a minute. Then tell me that you’re not blow away, and I’ll tell you that you are lying.

Speakers have always baffled me, and every time I try to understand how they actually work, it feels like my brain shortcuts.

This post is my final attempt to explain loudspeaker to myself.

The Anatomy of a Loudspeaker

A schema showing what parts a loudspeaker consists of.
Illustration by Svjo. License: CC BY-SA 3.0.

Compared to what it can do, the basic design of a speaker is frustratingly uncomplicated. A speaker typically contains of four very simple parts (the numbers correspond with the illustration above):

The Wikipedia article on loudspeakers explain how they work like this:

When an electrical signal is applied to the voice coil, a magnetic field is created by the electric current in the voice coil, making it a variable electromagnet. The coil and the driver’s magnetic system interact, generating a mechanical force that causes the coil (and thus, the attached cone) to move back and forth, accelerating and reproducing sound under the control of the applied electrical signal coming from the amplifier.

But HOW!?

How does the loudspeaker manage to create a particular sound when a particular current is received from the amplifier!?

Now I started to think about the amplifier. How the hell does it know what current to send to make the loudspeaker make the sound it wants!?

And what if the sound source is a vinyl record spinning on a record player? How does the grooves on the vinyl translate to sound waves!? How does the audio make its was from the vinyl record, through the pickup, the amplifier, the speaker, and all the way to our ears?

If there is a single proof that we’ve been visited by aliens, it’s the existence of loudspeakers. It’s alien technology, man! Either that, or black magic1.

There are certain things a man is not supposed to understand. Loudspeakers - and apparently amplifiers and vinyl records - are some of those things.

Thank you and good night.


  1. Did you know that a speaker can be used as a microphone? Mind blown! Again! ↩︎