A simple tutorial to do an hydrophone (aquatic microphone), step by step.
do it yourself following each step below.
Materials:
1. Mic cable (mono)
2. Thermofit
3. Piezoelectric sensor (on our video we used a 1″ piezo)
4. Plastic lids or “feet” for chairs or tables (with a diameter about 1cm bigger than piezoeletric’s diameter)
5. 1/4″mono jack plug
6. Iron washers
7. Rubber coating
8. Copper foil
9. Solder
10. Silicon
11. Electric tape
Tools:
1. Cutter
2. Scissors
3. Drilling machine
4. Drill
5. Hole saw (with a diameter a bit smaller than piezoelectric diameter)
6. Cutting plier
7. Soldering iron
8. Ruler
9. Permanent ink pen
10. Lighter
step 1: plastic lid preparation




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Choose a plastic lid with a diameter about 1cm bigger than piezoeletric’s diameter. In our video we used a 1″ piezo (25mm)
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With a ruler mark the center of the plastic piece
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Make a hole with the drilling machine and the hole saw. (The hole saw diameter should be a bit smaller than piezoelectric diameter)
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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.
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Measure the plastic lid height
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Cut the copper foil as a strip with the same height.
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Take the copper strip and internally cover the lid.
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Fix the copper ring with electrical tape
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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 and cable soldering




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Position the piezo centered outside of the lid. The terminals must be seen inside the hole.
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Fix it with electric tape. It will be removed on step 5.
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Before soldering put 2″of thermofit on both sides of the cable.
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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.
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Solder the 1/4″mono jack plug on the other side of the cable.
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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




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Fill half of the lid with silicon.
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Put 2 iron washers inside it. (In order to give some weight to the hydrophone)
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Fill the rest of the lid with silicon.
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Cut a copper foil circle, with the same diameter as the lid.
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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




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Carefully remove the electric tape from the piezo.
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Dip the lid in the rubber coating can and take it out very slowly.
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Let it dry for around 30 minutes and repeat this step 2 or 3 times.
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For a uniform rubber layer, you can turn the lid upside down while drying
step 6: Listening
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Try your hydrophone and share your recording
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Enjoy !!
TUTORIAL DONE by Sara Lana & Félix Blume
Other nice hydrophone tutorials where we learned to construct ours:
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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
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Zach Poff give a step by step building of a contact mic in a very easy way. With an interesting list of other places to buy some contact mic online (at the bottom of the page)
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John Grzinich share here a nice way to build a DIY hydrophone
If you want to buy some, here are a few links :
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Aquarian is one of the famous constructor of very good and cheap hydrophones, already very famous
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Dolphin Ear is doing very good hydrophones too (a bit more expensive)
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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)
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Jez Riley French is doing and selling a few models of contact and hydrophone since a long time now (at a good price too)
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Crank Sturgeon sells different models of contact mic (some are waterproof) done by himself
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Monkey Sound is doing and selling a few nice models too
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Geophone by LOM Audio. It is not an hydrophone, but it’s a very nice tool for contact recording
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Ambient sells ones of the best hydrophones, but with a much higher price
Missing a link to a nice DIY tutorial or another nice way of buying an hydrophone? Contact us!
https://saralana.xyz/about & https://felixblume.com/contact