Car Speaker Box Using a 'Folded Horn' Design

This project came about because a friend of mine sold me some great Vibe speakers real cheap that needed repairing.

Folded Horn speakers work like a trumpet in that the sound comes out of an expanding tube/box. To make it fit into small spaces the tube can be folded. As long as the fold continues to get wider then it has a chance of working.

 The rubber surround had split in a number of places. So I repaired the splits by using a rubber/latex glue called Copydex together with a very thin but strong rubberised cloth cut from a cheap glasses drawstring case/bag.

This is a view of the gluing. Several layers were added, but not too much as to restrict the speaker moving. Its not very pretty but it works, it takes 110 watts RMS with ease.

The design of the cabinet was inspired by cabs like this one shown at

www.decware.com 

The arrows in this pic show the path of the sound from behind the speaker in a folded horn design. An added benefit of using these designs is that you get sound form both the front and the back of the speaker. This means that less power is needed because the speaker is not compressing air in cabinet (to only produce heat) as a normal speaker does. All the energy is used to make sound, so you get about twice- ish the loudness you would get normally! Perfection.

Another bonus is that because the speaker is moving freely it sounds clearer, more detailed. Sound seems to travel further, like it is all around you, especially the bass. The only down side is that the speaker cone can travel beyond its limits if pushed too hard. But the vibe speakers I have are unlikely to do that with the limited amp I have.

Only bass comes out of the horn part of the speaker. LOADS of it. More than you would think possible. Horn speakers are brilliant.

No subwoofer will be necessary. The bass that I will get from these two speaker will out perform most of the closed box/ported subs I have heard, and with only 200 watts (these speakers will be very efficient in a folded horn design, a thousand watts are not needed).

This built speaker from the net shows the inside and outside, you can see how the internal port gradually gets bigger.

So some compromises were made, but as long as there was a chamber behind the speaker and the port gradually gets wider and wider then it will work.

Speaker Simulators

I didn’t use any of the simulators available on the net (for free) because I couldn’t be bothered to work out how to use them, and also with past experience folded horn speakers have all worked well so far. I’ve made 2 sets for the house in different rooms and one large pair (6 foot tall) for the band I play in.

This is it for the car. 

Next I had to make sure that it fitted in the boot so precise measurements were taken and clearances were added. It would need to be tilted into the boot space. A cover will be added so that isn’t possible to see it was there. 

The amplifier was screwed to it at the back where there was a space because the seats tilt back. there is still lots of room so that its stays cool. 

You can see here the way that the sound comes out of the front of the speakers and also travels around the inside of the box. The waves then join together to make ONE BIG wave.

This is the space it has to be big in.