Cardboard Horn Amplifier

Exponential Horns are amazing acoustical machines with no moving parts. They also look gorgeous!

Horn shapes were widely used by the ancient Greeks. They designed circular arenas which opened like funnels where if performers whispered on stage, their voices could be clearly heard from the uppermost seats. This is because of the unique characteristics of the acoustic horn which maximizes the efficiency with which sound waves are transferred to air from their source.

When the first gramophone was invented in 1898, its horn amplified the minute mechanical oscillations of a pin running along a disc to produce sounds that could be heard by the human ear.

In this Instructable, using a single sheet of cardboard, I created an amplifier that turns sounds from a smartphone into music that can fill an entire room.

To design my horn, I used Fusion360 to create a loft shape from 3 hexagon.
I then unrolled one of the sides of the lofted shapes to give me a flat pattern, I also added tabs so that when I assemble the horn these tabs will lock into each other.

I have attached a PDF with my patterns that you can use to either print and then hand cut or laser cut your cardboard!

I have now also included Letter sized tile print too!

To achieve a wrinkle-free smooth curve in the card board I scored the cardboard at every flute.

You will need to cut through the top and middle layer of the cardboard, this allows the cardboard to become flexible.

Now that you have cut all the cardboard for the horn and dock, score the dashed lines and assemble as shown in the images below.

Use tape to complete the dock.

Next assemble the horn by interlocking each 'petal' of your horn as shown ensuring that each tab is secured.

Insert the horn into the phone dock and your speaker is ready.

Put on your favorite music and enjoy pure and simple amplification!