The plinth forms the center of the room and the first puzzle in the escape room. The purpose of the plinth is to house the amplifier and USB sound-card for the room, but also house a concealed switch and two mysterious press buttons.

I mitered the corners of the plywood, because I’m not an end grain sort of a guy, until I make something entirely out of end grain ply.

The switch inside the plinth is simply two pieces of plywood, separated by 3 bolts with springs on their shank… obviously nylocks are essential here.

Here you can see that the contacts are just a loop/saddle which contacts against a metal plate. Some washers under the springs for good measure and the plinth is practically finished.

The lid of the plinth is also hinged and has a lock so that the room runner can access the sound system if needed.

The radio is not quite what it seems… those strange and cryptic buttons hidden on the plinth and around the room actually activate audio modules in this beauty.

Inside the radio there are two Arduino nano modules. One constantly reads the inputs from the buttons hidden around the room, and activates through serial communication the three MP3 audio modules when they are pressed. The three audio tracks are on separate SD cards in separate playback modules, which all run into a shared amplifier. The tracks are heavily fragmented and illegible when played individually, but when all three buttons are pressed simultaneously a fourth and complete track plays and the audio is legible.

The second Arduino nano module is connected to the radio speaker using an isolation transformer, and connected to the left audio channel of all three playback modules… The Arduino is performing an analog read on these two inputs, when audio passes through the speaker, the radio is illuminated with warm white light… however when the beeps embedded on the left audio channel are detected the face of the radio is illuminated in red. These red flashes correspond to very important clues on the audio track.