Talk Box Build

    For a musically inclined friend's birthday, I decided to make him a talk box since it was an instrument that he did not yet own and a concept I was interested in.  It also turned out to be cheaper to build than buying one outright and allows me to leave a little room for customization since this friend likes making his own electronics for altering audio signals.

    If you don't know what a talk box is, it is a musical instrument consisting of a speaker that projects sound into one's mouth by way of flexible tube.  That sound then exits the mouth into a microphone which serves as the next amplifying stage.  Here is a very impressive demonstration of perhaps the upper bounds of what the instrument can achieve.  Most people just make wah wah sounds.

    I started out with an off the shelf compression driver, which is a compact speaker that outputs its sound through a small diameter.  The idea was to replace the large horn that the component originally came with with a cap of my own design that would allow it to be mounted to a plate of 1/4" MDF and also have a nipple at the output that could attach to the flexible tube. 

Here is a stock image of the original part

I resin printed some nipples off the bat to test fit

Here is the first speaker assembly that I tested

The Invention Studio didn't have any 3.5mm jack port parts so I grabbed the signal with these probes

Early fit check with the laser-cut profile in 1/4" MDF

This is the diaphragm from inside the compression driver

Full compression driver assembly

    The component that moves in order to generate vibrations in the diaphragm is the coil.  The magnet (cylindrical component on the bottom left of the image) is static and the coil slides into the concentric circular slit.  The magnet is so massive that it would be infeasible to use it with such a small diaphragm.  Instead, the coil is what is attached to the diaphragm and can be thought as actuating itself when current flows.

First assembly after the housing design was finalized

By this point I had gotten my hands on a 3.5mm jack socket and could hook it up to my computer.

A peek inside shows that I have created a common interface with spades to connect the jack socket with the speaker.  The socket supports stereo audio signals, but with only one speaker, that's kind of useless.  There are ways of combining stereo signals into mono, but my friend is typically only going to use this for mono applications so I left it alone and editable.

No I never used the waterjet in the creation of this talk box... However, in the middle of this project was our waterjet cleanout and I wanted to capture how clear the water is!

To make the device presentable, I decided to give it a quick coat of paint

The paint booth had some satisfying, vivid colors that were sealed with a clear coat

Parts graveyard

To personalize the gift, I also laser cut a stencil for my friend's name and added it in purple

Here is the finished product with its new friends; notice the vinyl tube that I have neglected to show so far...

And finally, a demo:

    And that's the project finished on my end.  Plenty of space left in the box for whatever effects my friend wants to add and he's already talking about doing stuff with words I don't understand.  I've also uploaded the CAD to my grabcad for his reference and anyone else that wants to build this.