This was an existing (and unfinished) subwoofer that I was using for my home theatre a few years ago. The speaker is a ported design with two large PVC pipe fittings as external ports. By rotating the ports and submerging them I was hoping that the pressure exerted on the water would cause displacement and sound under the water. It did not produce any sound and as it was mains powered had the potential to kill if it fell into the pool.
After some research on (overpriced) commercial underwater transducers I attempted to build one. I didn't take any photos of the process but it is pretty straight forward:
- Sacrifice a reasonably sized woofer for its magnet and voice coil.
- Glue magnet into waterproof housing (pvc drain pipe in this case)
- Place voice coil in magnet for alignment and glue to front cap.
- Route wires, assemble and seal with glue. I am using RTV silicone.
Here is the submerged speaker: