Phone Amplifier

        With the proliferation of iPhone horns in the internet, I just had to make one for my phone too!

        For those not familiar, These devices are simply horns that 'amplify' the sound from the teeny built in speakers of phones to make it louder and sound a little better than the tinny sound they produce. Since it only does this using wave guides to make a better impedance match from the tiny speaker to the surrounding environment, there's no need for batteries.

        Thinking of a convenient way to make a horn from cardboard, I got inspiration from bass bins used in pro audio. The first version to test the proof of concept was made from cardboard. Here are some pics of the Phone Horn V1:

This is the chamber directly under the phone.

Here are the second and third expansion flare.

A view from the mouth side.

Another view assembled.

This is the bay where the phone goes onto.

        Since the cardboard proof of concept test was a success, I decided to make another more durable verison from MDF. Here are the pics I took when I built the V2 from 1/4" MDF and 1/8" laminate leftover from those ready to assemble furniture (think: Ikea furniture ):

Here's the milling machine setup for the top two panels.

Phone and top panel.

Here are the two panels completed beside the phone. You can see the phone bay and the first expansion flare.

Sandwiching the two together. The more clamps the better. Clamps are $1 jobbies from Harbor Freight.

Gluing the next panels.

Clamping the opposite side.

A couple pics from the other end.

Completed Phone Horn V2.

There is a curved piece of cardboard on the rear that I forgot to take pics of.

Worked really well. Still not HiFi standards but makes it louder and lower. Without the horn, The RTA showed it to drop to about 800Hz before rolling off. But when using the horn, it goes down to 400Hz before rolling off so that's another octave of extension.

Page updated and copyright R.Quan © 15 Jan 2012.