Passive AMP for smart phone

I have had a few requests for me to make a passive amp for smart phone. So I decided to take the challenge and give it a go. Now over all the idea is pretty simple the sound channeled to to the speaker chamber and hopefully resonates to make it that little louder. The one thing that it will most definitely and noticeably do is change the tone giving it a deeper and more rich sound. Will it beat the electronic one. Most definitely not but for what it actually is it is pretty cool and did surprise me a little on the difference it did make.

Video of build can be found here

And a full write up can be found here

-- Rome wasn't built in a day... but I wasn't on that job? ... http://www.wackywoodworks.co.nz