Experimenting with Underwater Mics and Opera

I was so happy to hear from Nell Ranney when she told me that The Observatory was starting up again.  I could put Choirs through water again! JumpCannon productions were putting the piece by librettist Sarah Grange and composer Steve Bentley-Klein for the Greenbelt Festival.  My Role in the piece was in the ‘space’ section, a large improvisation in the middle of the piece.  My setup the first time was homemade hydrophones (underwater microphones) in a large tank of water with speakers playing the voices of the singers at them.  This meant the voices were passed through the water being picked up by the hydrophones creating ethereal sounds.  I then experimented with these sounds, passing them through the water again and again, making the sounds murkier, voices overlapping in a wash of choral sound.

After listening through to the recordings we did for In Tune on BBC Radio 3 I decided I would improve the Microphones to get a better quality sound with lower tones translating well (Listen from about 14 minutes in).

After looking into lots of different underwater mics ranging from basic balloon on a normal mic to deep sea mics used to search for seabed volcanoes I decided how to make it, with piezo transducer discs. This are little discs that make electrical signals when picking up vibrations. The only thing is this is what I used last time! However after researching into these magic discs I found that what is more important than the disc is the preamp it is plugged into. After yet more research i found a schematic for a piezo disc preamp and got my breadboard out to test it.

Photo of me experimenting with my preamp and a wave drum
The preamp is at the top and a small contact mic is taped to a drum that appropriately sounds like waves.

That all worked fine so I got the soldering Iron out and stuck it all together.


I then got round to making the mic enclosure.  After filling up the waterproof box with vegetable oil and then taking it apart as it then floated (doh!) adding weight it worked really well. So well it could pic up sound of singers without amplification.  This meant I could experiment a lot more with the sounds, mixing in sounds of the instruments as well as the singers.


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Harry the Cellist looking very dapper during sound check

















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