Nuts and Volts - September 2017

SamplerBox should start right up. Next time you reboot, SamplerBox should automatically come up with your changes operational. This is all Linux stuff, and if you don’t need to change anything, you can safely ignore everything I just wrote.

Packaging

There are no requirements for packaging this project if you are only interested in experimenting with SamplerBox on the RaspPi. An exposed Pi with a bunch of protruding cables and USB modules does not a robust instrument make, however. Because I plan to keep my mellotron around for a long time and the fact that it will be moved around and probably even used in a live environment, meant that I needed to package it up for its own protection.

To this end, I built a 6-3/4” x 4-1/4” x 1-3/4” box made of 1/4” MDF and, of course, painted it a metal flake copper brown as shown in Figure 6. Figure 7 shows that the top of the box was made of 1/8” acrylic.

I suspended some perfboard from the acrylic top using 1/2” spacers. I mounted the RaspPi 3 underneath it and the LCD display on top.

The MIDI interface circuitry is built on the perfboard. Three pushbutton switches (Function,

Increment, and Decrement) are mounted directly to the acrylic top. On the right side of the box, I have mounted a 1/4” phone jack that internally is wired to the output of the USB DAC module. I have the power connector, reboot pushbutton switch, USB port connector, and the MIDI connector on the back of the box. The output jack, reset switch, and the power connector are glued to the box, whereas the USB port connector and the MIDI connector are mounted to the perfboard and protrude through holes machined in the back of the box.

I left enough slack in the wiring so that the top with the suspended circuit board can easily be lifted out of the box for maintenance. The rat’s nest of wiring is shown in Figure 8.

Figure 9 and Figure 10 show the operational SamplerBox.

Final Thoughts

Building the SamplerBox mellotron was challenging and fun, but having a functional mellotron around is even better. I already know my next series of recordings will have the ethereal sounds of the mellotron playing a prominent part.

You may be wondering why I didn’t just buy a keyboard with a large number of sounds available. To this, I have two answers. First, I enjoy building the things I use, and second, I am not aware of any keyboard that has mellotron sounds built in.

Remember, even though I use my SamplerBox mostly as a piano and mellotron, you could use one you build for yourself for drum sounds, brass instruments, human voices, or who knows what.