A simple tutorial to do an hydrophone (aquatic microphone), step by step. Do It Yourself following each step below.
- Mic cable (mono)
- Piezoelectric sensor (on our video we used a 1″ piezo)
- Plastic lids or “feet” for chairs or tables (with a diameter about 1cm bigger than piezoeletric’s diameter)
- 1/4″mono jack plug
- Iron washers
- Rubber coating
- Copper foil
- Electric tape
- Drilling machine
- Hole saw (with a diameter a bit smaller than piezoelectric diameter)
- Cutting plier
- Soldering iron
- Permanent ink pen
STEP 1 | PLASTIC LID PREPARATION
_ Choose a plastic lid with a diameter about 1cm bigger than piezoeletric’s diameter. In our video we used a 1″ piezo (25mm)
_ With a ruler mark the center of the plastic piece
_ Make a hole with the drilling machine and the hole saw.
(The hole saw diameter should be a bit smaller than piezoelectric diameter)
_ On the side of the plastic lid make a hole with the drill. It’s where the mic cable will pass through.
STEP 2 | COPPER FOIL
We will use the copper to protect the hydrophone from electro-magnetic interference.
_ Measure the plastic lid height
_ Cut the copper foil as a strip with the same height.
_ Take the copper strip and internally cover the lid.
_ Fix the copper ring with electrical tape
_ With scissors cut a hole on the side of the ring
Note: it exist a self-adhesive copper foil which could be better for this use (and easier to work with)
STEP 3 | PIEZO & CABLE SOLDERING
_ Position the piezo centered outside of the lid. The terminals must be seen inside the hole.
_ Fix it with electric tape. It will be removed on step 5.
_ Before soldering put 2″of thermofit on both sides of the cable.
_ Pass the mic cable through the lid and copper holes and solder it on piezo’s terminals : ground on the external part, positive on the internal part of the piezo.
_ Solder the 1/4″mono jack plug on the other side of the cable.
_ After soldering, reposition the thermofit and get it hot with the lighter.
Note: it would be possible to use a stereo cable to have probably better shielding. You should then connect ground to the copper foil, positive on the center and negative on the external part of the piezo.
STEP 4 | Silicon and iron washers
_ Fill half of the lid with silicon.
_ Put 2 iron washers inside it. (In order to give some weight to the hydrophone)
_ Fill the rest of the lid with silicon.
_ Cut a copper foil circle, with the same diameter as the lid.
_ Put the copper circle on the top of the silicon, so it will get glued._ Wait until the silicon dries (about 30 minutes)
Note: you could put some weight on top of the copper foil, so it will get straighter.
STEP 5 | Rubber coating
_ Carefully remove the electric tape from the piezo.
_ Dip the lid in the rubber coating can and take it out very slowly.
_ Let it dry for around 30 minutes and repeat this step 2 or 3 times.
_ For a uniform rubber layer, you can turn the lid upside down while drying
STEP 6 | Listening
_ Try your hydrophone and share your recording
TUTORIAL by Sara Lana & Félix Blume
Other nice hydrophone tutorials where we learned to construct ours:
- Phase 57 give a very similar way of building a contact microphone, shield as ours, and I guess that could easily be used as a hydrophone
- Zach Poff
- John Grzinich
- Guillaume Leguen
- Locus Sonus | Grégoire Lauvin
- David Dunn
- LOM contact microphone and interesting things about piezo
- Tim Prebble about contact microphone
- Alek Dikarev on Instructables
- Action Owl on Instructables using oil and electret
- Leafcutter John doing with a metal box
- Tristan Louth Robins very simple, only with hot glue
If you want to buy some, here are a few links :
- Aquarian is one of the famous constructor of very good and cheap hydrophones, already very famous
- Dolphin Ear is doing very good hydrophones too (a bit more expensive)
- Cold Gold has a lot of different models of contact mic and hydrophone, at very good prices (including some piezo and copper foil for DIY mic)
- Jez Riley French is doing and selling a few models of contact and hydrophone since a long time now (at a good price too)
- Crank Sturgeon sells different models of contact mic (some are waterproof) done by himself
- Monkey Sound is doing and selling a few nice models too
- Geophone by LOM Audio. It is not an hydrophone, but it’s a very nice tool for contact recording https://store.lom.audio/products/geofon
- Ambient is of course sells ones of the best hydrophones, but with a much higher price https://ambient.de/en/product_custom_cat/underwater-en/