AusOcean Underwater Speaker Guide
Note this version is deprecated for AusOcean use. See updated guide for current version.
Created: 10th February 2019
Revised: 22nd June 2020
Trek Hopton <email@example.com>
Frank Cui <firstname.lastname@example.org>
Copyright © The Australian Ocean Laboratory Limited (AusOcean) 2020.
The information contained herein is licensed under a Creative Commons Attribution 3.0 Australia License.
AusOcean is not liable for any losses, damages, costs and/or other consequences resulting directly or indirectly from using or relying on the information in this document.
Table of contents
AusOcean speakers are utilised for audio playback underwater for reef sound treatment applications, typically at areas directly below the supporting rig. The speakers are considered a peripheral therefore, are powered and controlled by the on board controller. The rig acts as a base to provide sufficient power for indefinite operation or until the end of a data collection period.
The processes demonstrated in this guide were all executed while using appropriate safety equipment and measures. These are, but not limited to, gloves and safety glasses. Other essential equipment is listed below.
The housing, the main structure that encapsulates the surface transducer (speaker) and the terminals of the corresponding audio cable.
Use the hacksaw to cut a length of 60mm from the 90mm PVC pipe.
Use the drill with a 10mm bit to drill a hole in the centre of one PVC cap.
Sand any rough burs on the pipe and caps from the cutting and drilling process until you have smooth edges.
Lightly sand the surfaces on the inside lip of the caps, the outside rim of the pipe, and the rim of the conduit reducer to ensure good bonding surfaces for gluing.
Fully remove any logos or stamps off the cap with the hole drilled into it. The surface area around the hole must be smooth to ensure a strong bond when gluing.
Also, sand any logos or stamps off the other cap so the front of the speaker is smooth too.
Use JB Weld to glue the vibrating face of the speaker to the inside center of the front cap (without a hole).
Ensuring not to move the speaker, use PVC cement to glue the pipe into the cap. This join needs to be watertight so use a generous amount of cement around the inside of the cap and the outside rim of the pipe.
Use PVC cement to glue the conduit reducer to the center of the cap with a hole in it.
Take one end of the two-core cable and strip the outer plastic jacke to expose 40mm of the two inner cables (strip outer black cover back 40mm).
Further strip the plastic jackets off the smaller inner cables to expose 8mm of bare wire.This will be the speaker end of the wire.
Once the PVC cement on the reducer has been left for 15 minutes to harden, cut a square of duct tape and block the 10mm hole on the inside of the cap. Using a sharp tool to puncture a hole through the centre of the tape. Thread the exposed speaker end cable until 80mm has been fed through.
This connection is called a C5 connection and a detailed guide can be found here.
Tip: use a roll of duct tape as a support for the cap to keep it horizontal while gluing. The center hole of the roll allows the cable to hang below without tilting the cap.
Secure the cable vertically so that it won’t move, then fill the reducer with 10mm of JB Weld.
Tip: wrap some tape above the 10mm mark so that once the glue has cured, it can be removed, leaving a clean cable.
Tip: mix the JB Weld on the inside corner of a ziplock bag. When mixed, cut a tiny hole in the corner and use it as a nozzle for higher accuracy.
Once the JB Weld has been left for 4 hours to harden, fill the remainder of the reducer with Sikaflex and taper it up the side of the cable. This will improve the cable’s flexibility.
Tip: Once the Sikaflex has been left to harden for at least an hour, wrap the connection in tape to tidy it up.
The amplifier and other electronics responsible for audio playback are located at the opposite end of the audio cable. The electronics are grouped together into a speaker module, which is typically positioned up the mast of a rig. A basic schematic is illustrated below.
The following table provides component names, suggested supplier and image for reference. These components, however, are only suggestions, other variations of these could be used instead.
Solder the red wire from the speaker to the red wire on the speaker end of the cable, and the black wire from the speaker to the black wire on the speaker end of the cable.
Use electrical tape or heat shrink to ensure that the bare wires can not touch each other.
Tip: if you don’t have a soldering iron, crimp connectors can be used to splice the wires instead.
(Optional, depending on what amplifier / playback device you are connecting the speaker to).
Strip the plastic jackets off of the plug end of the cable exposing 5mm of bare wire.
Unscrew the cover of the 3.5mm plug and slide it onto the cable.
Solder the black wire to the long ground conductor of the 3.5mm plug.
Solder the red wire to the short signal conductor of the 3.5mm plug.
Slide electrical tape between the soldered connections to ensure that the black wire and ground conductor cannot touch the red wire and signal conductor.
Tip: if you have a stereo plug, orient the long ground conductor so that it is on the bottom with the plug facing away, solder the red wire to the left short conductor. Mono audio should travel through the left channel.
Screw the plug’s cover back on.
This is a good point to test the speaker before gluing the front and back together.
Connect it to an amplifier or playback device and play a sound through it. The sound should come from the front assembly.
If the sound is too quiet and the device’s volume can’t go higher, that indicates the need for an amplifier which can be used between the device and the speaker.
If you don’t hear any sound, it’s possible that some wires are shorting or there is a faulty connection. Check all the soldered connections and make sure the red and black wires are not touching. Stick electrical tape between the wires or contacts if necessary.
Use a generous amount of PVC cement to glue the front assembly to the back assembly.
Apply a significant amount of pressure for 5 minutes. The air inside will want to push the cap outward. The easiest way to do this is with a couple of G clamps or F clamps on opposite sides of the speaker. Be careful not to over tighten.
Wait 24 hours for the PVC cement to fully cure before testing the speaker underwater.
$ sudo raspi-config
$ sudo apt-get update
$ sudo apt-get -y upgrade
$ wget https://dl.google.com/go/go1.13.5.linux-armv6l.tar.gz.
$ tar -xvf go1.13.5.linux-armv6l.tar.gz
$ sudo mv go /usr/local
$ sudo nano ~/.profile
$ source ~/.profile
$ go version
$ sudo apt install git
Verify that it is installed by typing:
$ git --version
$ cd ~
$ mkdir -p go/src/bitbucket.org/ausocean
$ cd go/src/bitbucket.org/ausocean
$ git clone http://bitbucket.org/ausocean/av
$ sudo apt install ffmpeg
Verify the install using:
$ ffmpeg -version
$ sudo apt install omxplayer
$ cd ~/go/src/bitbucket.org/ausocean/av/cmd/looper
$ sudo make install_hard
$ sudo nano /etc/rc.local
sudo ./looper -path=/home/pi/example.mp3 &
$ sudo systemctl enable rc-local
$ sudo systemctl start rc-local.service
$ sudo reboot
Sound should eventually play once the device has booted again!
Your speaker is now finished and ready to record some sounds under water!
The Australian Ocean Laboratory Limited (AusOcean)