> I would like to know if anyone out there already managed to record them and
> could give me any suggestions and links to listen to the results.
> Also I never used geophones yet and I would like to know if there is a good
> affordable model to consider out there.
Emanuele,
Years ago, I was the recordist filming white water rafting in Papua New
Guinea, which was loud and rough and had lots of close up LF. I also had to
get our female presenter shouting and shrieking over the noise. Although she
was wearing the rig, her shouts only just came out as the river water was so
loud.
I originally considered radio mics but they were too expensive to risk. I
found a Walkman (remember them?) waterproof wallet designed to enable
surfers to listen to music. Using affordable mics, I waterproofed them with
small foam puffgags covered with a condom and sealed the lead both ends with
silicone setting rubber.
A problem with some hydrophones I have listened to is that the bass is weak
and they have a peak in the middle frequencies, but you should be able to
equalise the recording later. However, where would you fix the hydrophone?
It is easier to keep to one package with no leads to tug or leak.
A parabola or a long gunmic would not have the directivity to get the close
roar you want. Nowadays I would go for a sealed heavy duty polythene bag and
an "affordable" (ie. expendable) recorder with built in mics wrapped in thin
acoustic foam. You would need to keep the record volume probably lower than
you think. If you can find waterproof gaffer tape, tape it to the surfer's
chest or leg or whatever, otherwise make up a strap-on canvas pouch with a
gap opposite the mics.
You really don't need to worry too much about sound quality. System noise
will be non-existent and lumpy frequency responses can be evened out later.
Take spare kits and use a domestic heat sealer so you can open up and make
modifications according to what you hear back later. You won't be able to
monitor the recording in real time. You will have to push record then leave
these rigs running, as I did with the Walkman, but you have longer run times
now.
David Brinicombe
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