DIY Talking/Music/Sound Effect Playing Styrofoam Gravestone With Hidden Bluetooth Speaker

A unique way to add a little extra spooky to your Halloween graveyard is by adding audio effects that seem to come from nowhere and everywhere at the same time. I will show you how I easily turned Styrofoam gravestones into completely stealth battery powered Bluetooth enabled speakers to play music, Halloween sound effects, and even clips of Freddy's voice!

Parts Needed:

1 x Styrofoam gravestone - Dollar Store or get a fancy one like me :)

1 x PE3W-BT Rechargeable Portable 2x3W Bluetooth Amplifier (320-630)

2 x Dayton Audio DAEX25CT-4 Coin Type 25mm Exciter 10W 4 Ohm (295-220)

Tools Needed:

Wire Cutters/Strippers

Soldering Iron and Solder

An exciter is essentially a loudspeaker without a cone or diaphragm. The idea is you can attach an exciter to any light but rigid surface and they will turn that surface into a speaker. There are many practical uses for exciters since they can be used to create completely invisible speakers that can be capable of impressive sound quality. Now, this isn't the most practical use and don't expect it to sound great, but it does get surprisingly loud and create a pretty cool effect that's perfect for startling someone.

There are many different sizes and types of exciters. I chose the Dayton Audio DAEX25CT-4 for this project for a few different reasons. First, and most importantly, this exciter is very efficient and has quite a bit of mass. That means that with very little input power (I am just using a 3 watt amplifier) you can get a lot of sound. Also, this exciter has a pretty well sealed housing so if I do happen to forget to bring this in when it rains there is less chance of water getting inside and damaging the exciter (there are waterproof exciters, but in this case the amplifier is not waterproof so I figured why bother).

First, you need to attach the exciter to the output wires of the PE3W-BT amplifier. Unfortunately, the PE3W-BT amplifier has solderless disconnect terminals and this exciter has solder tabs.

Using wire cutters/strippers cut off the solderless disconnects and strip about 1/2" of the wire.

Twist the wire strands tightly. Insert about half of the stripped wire through the solder tab hole on the exciter. Fold the wire over and wrap it tightly back around itself as shown.

Repeat for all 4 wires. Be sure to observe polarity as you do this, connect the red wires to the "+" tabs and the yellow wires to the "-" tabs (polarity is marked on the back side of the exciter).

Next, solder the connections. When soldering I recommend applying the heat to the wire instead of the solder tab itself to minimize the chance of damaging the exciter from excessive heat.

As always, make sure the solder flows into the wire and solder tab. You don't want a glob of solder just sitting on the wire.

Add a little bit of protection to the connection by sliding the original insulators from the solderless disconnects directly over the solder tabs. I do recommend heat shrink tubing for this (I didn't have any on hand), but this can work in a pinch.

Finally, just peel off the self-adhesive backing from the exciters and place on the gravestone. Optimal placement can take a lot of trial and error, but since this isn't exactly a hi-fidelity application you can really stick them almost anywhere. Also, it isn't necessary to use two exciters on each gravestone. One exciter per gravestone would be plenty and by separating the left and right signals (left and right gravestones) you can pull off some very good stereo effects.

The finished project. From the front, the gravestone has not changed one bit. A completely invisible speaker.

Here's how the set up looks outside with the stakes secured and the speaker elements in place.

Just turn on the PE3W-BT amplifier and sync it to a phone or tablet. Then you can easily stream Halloween themed background music, spooky sound effects, or even use a microphone app to talk directly to trick-or-treaters through the gravestone. If you have multiple tablets and/or phones you can sync them to separate PE3W-BT amplifiers to play music, effects, and voice all at the same time for a truly chilling experience.

Happy Halloween!